Sample records for ablation electrode-induced displacement

  1. Microwave Ablation Using Four-Tine Antenna: Effects of Blood Flow Velocity, Vessel Location, and Total Displacement on Porous Hepatic Cancer Tissue

    Chaichanyut, Montree


    This research is concerned with microwave ablation analyses using a 2.45 GHz four-tine (4T) antenna for hepatic cancer tissue. In the study, three-dimensional finite-element models were utilized to examine the tissue temperature distributions during and after MW ablation. A preliminary study was first carried out with regard to the specific absorption rates along the 4T antenna insertion depths and the temperature distributions inside the solid and porous liver models with either 3 cm-in-diameter tumor or 5 cm-in-diameter tumor. Based on the preliminary results, the porous models were further examined for the effect of varying blood flow velocities (0–200 cm/s) with a 1 cm-in-diameter blood vessel next to the antenna and also for the effect of vessel-antenna locations (0, 0.8, and 1.3 cm) with a constant blood flow velocity of 16.7 cm/s. All scenarios were simulated under temperature-controlled mode (90°C). The findings revealed that the blood flow velocity and vessel location influence the ablation effectiveness and that increased blood flow inhibits heat transfer to the vessel wall. At the nearest and farthest vessel-antenna locations (0 and 1.3 cm), approximately 90.3% and 99.55% of the cancer cells were eradicated except for the areas adjacent to the vessel. In addition, total tissue thermal displacement is 5.9 mm which is 6.59% of the total length of the overall model. PMID:27642364

  2. Microwave Ablation Using Four-Tine Antenna: Effects of Blood Flow Velocity, Vessel Location, and Total Displacement on Porous Hepatic Cancer Tissue

    Montree Chaichanyut


    Full Text Available This research is concerned with microwave ablation analyses using a 2.45 GHz four-tine (4T antenna for hepatic cancer tissue. In the study, three-dimensional finite-element models were utilized to examine the tissue temperature distributions during and after MW ablation. A preliminary study was first carried out with regard to the specific absorption rates along the 4T antenna insertion depths and the temperature distributions inside the solid and porous liver models with either 3 cm-in-diameter tumor or 5 cm-in-diameter tumor. Based on the preliminary results, the porous models were further examined for the effect of varying blood flow velocities (0–200 cm/s with a 1 cm-in-diameter blood vessel next to the antenna and also for the effect of vessel-antenna locations (0, 0.8, and 1.3 cm with a constant blood flow velocity of 16.7 cm/s. All scenarios were simulated under temperature-controlled mode (90°C. The findings revealed that the blood flow velocity and vessel location influence the ablation effectiveness and that increased blood flow inhibits heat transfer to the vessel wall. At the nearest and farthest vessel-antenna locations (0 and 1.3 cm, approximately 90.3% and 99.55% of the cancer cells were eradicated except for the areas adjacent to the vessel. In addition, total tissue thermal displacement is 5.9 mm which is 6.59% of the total length of the overall model.

  3. Catheter Ablation

    ... ablation. Visit Cardiac ablation procedures and Cardiac conduction system for more information about this topic. Related ... National Institutes of Health Department of Health and Human Services

  4. Displacement Ventilation

    Nielsen, Peter Vilhelm

    Displacement ventilation is an interesting new type of air distribution principle which should be considered in connection with design of comfort ventilation in both smal1 and large spaces. Research activities on displacement ventilation are large all over the world and new knowledge of design...... methods appears continuously. This book gives an easy introduction to the basis of displacement ventilation and the chapters are written in the order which is used in a design procedure. The main text is extended by five appendices which show some of the new research activities taking place at Aalborg...

  5. Displacement Ventilation

    Bjørn, Erik; Mattsson, Magnus; Sandberg, Mats

    Full-scale experiments were made in a displacement ventilated room with two breathing thermal manikins to study the effect of movements and breathing on the vertical contaminant distribution, and on the personal exposure of occupants. Concentrations were measured with tracer gas equipment...

  6. Electrode-induced digital-to-analog resistive switching in TaO x -based RRAM devices.

    Li, Xinyi; Wu, Huaqiang; Bin Gao; Wu, Wei; Wu, Dong; Deng, Ning; Cai, Jian; Qian, He


    In RRAM devices, electrodes play a significant role during the switching process. In this paper, different top electrodes are used for TaO y /Ta2O5-x /AlO σ triple-oxide-layer devices. Top electrode-induced digital resistive switching to analog resistive switching was observed. For Pt top electrode (TE) devices, abrupt digital resistive switching behavior was observed, while Al TE devices showed gradual analog resistive switching behavior. Devices with various AlO σ thicknesses and sizes were fabricated and characterized to evaluate the reliability of the analog resistive switching. The physical mechanisms responsible for this electrode-induced resistive switching behavior were discussed.

  7. Displacing use

    Kelly, Janet; Matthews, Ben


    -centred design process. We identified alternative design-relevant relationships between people and devices that are not specifically tied to the functions/uses of the devices, e.g. relationships between the healthcare professional and the device, between doctors and patients, and between patients and their own......This paper critically discusses the concept of use in design, suggesting that relevant relationships other than use are sometimes obscured by the usercentredness of design processes. We present a design case from the medical device domain that displaced the concept of use from the centre of a human...

  8. Nanoscale ablation through optically trapped microspheres

    Fardel, Romain; McLeod, Euan; Tsai, Yu-Cheng; Arnold, Craig B.


    The ability to directly create patterns with size scales below 100 nm is important for many applications where the production or repair of high resolution and density features is needed. Laser-based direct-write methods have the benefit of being able to quickly and easily modify and create structures on existing devices, but ablation can negatively impact the overall technique. In this paper we show that self-positioning of near-field objectives through the optical trap assisted nanopatterning (OTAN) method allows for ablation without harming the objective elements. Small microbeads are positioned in close proximity to a substrate where ablation is initiated. Upon ablation, these beads are temporarily displaced from the trap but rapidly return to the initial position. We analyze the range of fluence values for which this process occurs and find that there exists a critical threshold beyond which the beads are permanently ejected.

  9. Job Displacement and Crime

    Bennett, Patrick; Ouazad, Amine

    that displaced workers' propensity to commit crime is higher than non-displaced workers before the displacement event; but it is significantly higher afterwards. Displacement impacts crime over and above what is explained by earnings losses and weeks of unemployment following displacement....

  10. Job Displacement and Crime

    Bennett, Patrick; Ouazad, Amine

    individuals, i.e. high-tenure workers with strong attachment to their firm, who lose employment during a mass-layoff event. Pre-displacement data suggests no evidence of endogenous selection of workers for displacement during mass-layoffs: displaced workers’ propensity to commit crime exhibits...... theory of crime. Marital dissolution is more likely post-displacement, and we find small intra-family externalities of adult displacement on younger family members’ crime. The impact of displacement on crime is stronger in municipalities with higher capital and labor income inequalities....

  11. Statelessness and environmental displacement

    Jessie Connell


    Full Text Available Stateless people and migrants are at greater risk of displacement and are less likely to receive assistance; in turn, environmental displacement (especially multiple migrations heightens the risk of becoming stateless.

  12. Laser ablation principles and applications


    Laser Ablation provides a broad picture of the current understanding of laser ablation and its many applications, from the views of key contributors to the field. Discussed are in detail the electronic processes in laser ablation of semiconductors and insulators, the post-ionization of laser-desorbed biomolecules, Fourier-transform mass spectroscopy, the interaction of laser radiation with organic polymers, laser ablation and optical surface damage, laser desorption/ablation with laser detection, and laser ablation of superconducting thin films.

  13. Job Displacement and Crime

    Bennett, Patrick; Ouazad, Amine

    This paper matches a comprehensive Danish employer-employee data set with individual crime information (timing of offenses, charges, convictions, and prison terms by crime type) to estimate the impact of job displacement on an individual’s propensity to commit crime. We focus on displaced individ...

  14. XY displacement device

    Heerens, W.C.; Laham, C.D.; Holman, A.E.


    An XY-displacement device (1) with a four-fold symmetry comprises a reference frame (10); an object mount (20) for holding an object (22) to be displaced; an X-manipulator (100) coupled between the reference frame (10) and the object mount (20), which provides a rigid coupling between the object mou

  15. Displacement data assimilation

    Rosenthal, W. Steven; Venkataramani, Shankar; Mariano, Arthur J.; Restrepo, Juan M.


    We show that modifying a Bayesian data assimilation scheme by incorporating kinematically-consistent displacement corrections produces a scheme that is demonstrably better at estimating partially observed state vectors in a setting where feature information is important. While the displacement transformation is generic, here we implement it within an ensemble Kalman Filter framework and demonstrate its effectiveness in tracking stochastically perturbed vortices.

  16. Radiofrequency ablation in dermatology

    Sachdeva Silonie


    Full Text Available Radiofreqeuency ablation is a versatile dermatosurgical procedure used for surgical management of skin lesions by using various forms of alternating current at an ultra high frequency. The major modalities in radiofrequency are electrosection, electrocoagulation, electrodessication and fulguration. The use of radiofrequency ablation in dermatosurgical practice has gained importance in recent years as it can be used to treat most of the skin lesions with ease in less time with clean surgical field due to adequate hemostasis and with minimal side effects and complications. This article focuses on the major tissue effects and factors influencing radiofrequency ablation and its application for various dermatological conditions.

  17. Advanced Triangulation Displacement Sensors

    Poteet, Wade M.; Cauthen, Harold K.


    Advanced optoelectronic triangulation displacement sensors undergoing development. Highly miniaturized, more stable, more accurate, and relatively easy to use. Incorporate wideband electronic circuits suitable for real-time monitoring and control of displacements. Measurements expected to be accurate to within nanometers. In principle, sensors mass-produced at relatively low unit cost. Potential applications numerous. Possible industrial application in measuring runout of rotating shaft or other moving part during fabrication in "zero-defect" manufacturing system, in which measured runout automatically corrected.

  18. Displacement Data Assimilation

    Rosenthal, W Steven; Mariano, Arthur J; Restrepo, Juan M


    We show that modifying a Bayesian data assimilation scheme by incorporating kinematically-consistent displacement corrections produces a scheme that is demonstrably better at estimating partially observed state vectors in a setting where feature information important. While the displacement transformation is not tied to any particular assimilation scheme, here we implement it within an ensemble Kalman Filter and demonstrate its effectiveness in tracking stochastically perturbed vortices.

  19. Iraqi Population Displacement Analysis


    CENTER FOR ARMY ANALYSIS 6001 GOETHALS ROAD FORT BELVOIR, VA 22060-5230 CAA-2015098 IRAQI POPULATION DISPLACEMENT ANALYSIS NOVEMBER 2016...designated by other official documentation. Comments or suggestions should be addressed to: Director Center for Army Analysis ATTN: CSCA-OA...CONTRACT NUMBER Iraqi Population Displacement Analysis PDMC 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Ms

  20. Advanced Triangulation Displacement Sensors

    Poteet, Wade M.; Cauthen, Harold K.


    Advanced optoelectronic triangulation displacement sensors undergoing development. Highly miniaturized, more stable, more accurate, and relatively easy to use. Incorporate wideband electronic circuits suitable for real-time monitoring and control of displacements. Measurements expected to be accurate to within nanometers. In principle, sensors mass-produced at relatively low unit cost. Potential applications numerous. Possible industrial application in measuring runout of rotating shaft or other moving part during fabrication in "zero-defect" manufacturing system, in which measured runout automatically corrected.

  1. Internal displacement in Burma.

    Lanjouw, S; Mortimer, G; Bamforth, V


    The internal displacement of populations in Burma is not a new phenomenon. Displacement is caused by numerous factors. Not all of it is due to outright violence, but much is a consequence of misguided social and economic development initiatives. Efforts to consolidate the state by assimilating populations in government-controlled areas by military authorities on the one hand, while brokering cease-fires with non-state actors on the other, has uprooted civilian populations throughout the country. Very few areas in which internally displaced persons (IDPs) are found are not facing social turmoil within a climate of impunity. Humanitarian access to IDP populations remains extremely problematic. While relatively little information has been collected, assistance has been focused on targeting accessible groups. International concern within Burma has couched the problems of displacement within general development modalities, while international attention along its borders has sought to contain displacement. With the exception of several recent initiatives, few approaches have gone beyond assistance and engaged in the prevention or protection of the displaced.

  2. Moldable cork ablation material


    A successful thermal ablative material was manufactured. Moldable cork sheets were tested for density, tensile strength, tensile elongation, thermal conductivity, compression set, and specific heat. A moldable cork sheet, therefore, was established as a realistic product.

  3. femtosecond laser ablation

    Margetic, Vanja


    Femtosecond laser ablation was investigated as a solid sampling method for elemental chemical analysis. In comparison to the sampling with longer laser pulses, two aspects could be improved by using ultrashort pulses: elimination of the elemental fractionation from the ablation crater, which is necessary for an accurate quantitative analysis, and better control of the material removal (especially for metals), which increases the spatial resolution of microanalysis. Basic aspects of ultrashort...

  4. Right atrial aneurysm with downward displacement of the anterior leaflet that resembled Ebstein's anomaly.

    Yamauchi, Sanae; Suzuki, Yasuyuki; Daitoku, Kazuyuki; Kimura, Masaomi; Okumura, Ken; Fukuda, Ikuo


    A 13-year-old boy presented with right atrial aneurysm and downward displacement of the anterior leaflet in the tricuspid valve into the right ventricle, without tricuspid valve regurgitation. Paroxysmal atrial flutter was caused by an abnormal electrical re-entry circuit, which could not be treated using catheter radiofrequency ablation. Therefore, the patient underwent surgical ablation and resection of the enlarged right atrial wall. The anterior leaflet of the tricuspid valve was plastered and displaced downward into the right ventricle, which resembled Ebstein's anomaly. Pathological evaluation revealed a thin wall that contained fibrous tissue with lipomatous degeneration and few muscular elements. No postoperative arrhythmia was observed.

  5. Supersymmetric Displaced Number States

    Fredy R. Zypman


    Full Text Available We introduce, generate and study a family of supersymmetric displaced number states (SDNS that can be considered generalized coherent states of the supersymmetric harmonic oscillator. The family is created from the seminal supersymmetric boson-fermion entangling annihilation operator introduced by Aragone and Zypman and later expanded by Kornbluth and Zypman. Using the momentum representation, the states are obtained analytically in compact form as displaced supersymmetric number states. We study their position-momentum uncertainties, and their bunchiness by classifying them according to their Mandel Q-parameter in phase space. We were also able to find closed form analytical representations in the space and number basis.

  6. Job Displacement and Crime

    Bennett, Patrick; Ouazad, Amine

    We use a detailed employer-employee data set matched with detailed crime information (timing of crime, fines, convictions, crime type) to estimate the impact of job loss on an individual's probability to commit crime. We focus on job losses due to displacement, i.e. job losses in firms losing...

  7. Displacement compressors - acceptance tests

    International Organization for Standardization. Geneva


    ISO 1217:2009 specifies methods for acceptance tests regarding volume rate of flow and power requirements of displacement compressors. It also specifies methods for testing liquid-ring type compressors and the operating and testing conditions which apply when a full performance test is specified.

  8. Transient Ablation of Teflon Hemispheres

    Arai, Norio; Karashima, Kei-ichi; Sato, Kiyoshi


    For high-speed entry of space vehicles into atmospheric environments, ablation is a practical method for alleviating severe aerodynamic heating. Several studies have been undertaken on steady or quasi-steady ablation. However, ablation is a very complicated phenomenon in which a nonequilibrium chemical process is associated with an aerodynamic process that involves changes in body shape with time. Therefore, it seems realistic to consider that ablation is an unsteady phenomenon. In the design of an ablative heat-shield system, since the ultimate purpose of the heat shield is to keep the internal temperature of the space vehicle at a safe level during entry, the transient heat conduction characteristics of the ablator may be critical in the selection of the material and its thickness. This note presents an experimental study of transient ablation of Teflon, with particular emphasis on the change in body shape, the instantaneous internal temperature distribution, and the effect of thermal expansion on ablation rate.

  9. Power Laser Ablation Symposia

    Phipps, Claude


    Laser ablation describes the interaction of intense optical fields with matter, in which atoms are selectively driven off by thermal or nonthermal mechanisms. The field of laser ablation physics is advancing so rapidly that its principal results are seen only in specialized journals and conferences. This is the first book that combines the most recent results in this rapidly advancing field with authoritative treatment of laser ablation and its applications, including the physics of high-power laser-matter interaction. Many practical applications exist, ranging from inertial confinement fusion to propulsion of aerostats for pollution monitoring to laser ignition of hypersonic engines to laser cleaning nanoscale contaminants in high-volume computer hard drive manufacture to direct observation of the electronic or dissociative states in atoms and molecules, to studying the properties of materials during 200kbar shocks developed in 200fs. Selecting topics which are representative of such a broad field is difficu...

  10. The photoelectric displacement converter

    Dragoner, Valeriu V.


    In the article are examined questions of constructing photoelectric displacement converter satisfying demands that are stated above. Converter has channels of approximate and precise readings. The approximate reading may be accomplished either by the method of reading from a code mask or by the method of the consecutive calculation of optical scale gaps number. Phase interpolator of mouar strips" gaps is determined as a precise measuring. It is shown mathematical model of converter that allow evaluating errors and operating speed of conversion.

  11. Tumor ablations in IMRI

    Roberto Blanco Sequeiros


    @@ IntroductionMagnetic resonance imaging based guidance control and monitoring of minimally invasive intervention has developed from a hypothetical concept to a practical possibility. Magnetic-resonance-guided interstitial therapy in principle is defined as a treatment technique for ablating deepseated tumors in the human body.


    Xu Longxiang; Zhang Jinyu; Schweitzer Gerhard


    A high temperature displacement sensor based on the principle of eddy-current is investigated. A new temperature compensation technique by using eddy-current effect is presented to satisfy the special requirement at high temperature up to 550℃. The experiment shows that the temperature compensation technique leads to good temperature stability for the sensors. The variation of the sensitivity as well as the temperature drift of the sensor with temperature compensation technique is only about 7.4% and 90~350 mV at 550℃ compared with that at room temperature, and that of the sensor without temperature compensation technique is about 31.2% and 2~3 V at 550℃ compared with that at room temperature. A new dynamic calibration method for the eddy-current displacement sensor is presented, which is very easy to be realized especially in high frequency and at high temperatures. The high temperature displacement sensors developed are successfully used at temperature up to 550℃ in a magnetic bearing system for more than 100 h.

  13. Effect of oblique force source induced by laser ablation on ultrasonic generation.

    Guo, Yuning; Yang, Dexing; Chang, Ying; Gao, Wei


    The effect of asymmetry caused by oblique line-shaped laser ablation on the generation of ultrasonic waves in metal, especially the effect of transverse component of the ablation force source on the ultrasonic waves is analyzed. Due to the oblique force source, the displacements of shear wave increase obviously by the enhanced shear force, the energy concentration area of longitudinal wave deflects to the small range centered on the incident direction while that of shear wave is approximately perpendicular to incident direction. In addition, surface wave enhances in the direction of transverse power flow. Furthermore, some ultrasonic characteristics under vortex laser ablation condition are inferred.

  14. Second Order Darboux Displacements

    Samsonov, B F; Negro, J; Nieto, L M


    The potentials for a one dimensional Schroedinger equation that are displaced along the x axis under second order Darboux transformations, called 2-SUSY invariant, are characterized in terms of a differential-difference equation. The solutions of the Schroedinger equation with such potentials are given analytically for any value of the energy. The method is illustrated by a two-soliton potential. It is proven that a particular case of the periodic Lame-Ince potential is 2-SUSY invariant. Both Bloch solutions of the corresponding Schroedinger equation equation are found for any value of the energy. A simple analytic expression for a family of two-gap potentials is derived.

  15. Displacing the patient

    Pors, Anja Svejgaard


    This analysis is based on an empirical study of a Danish hospital‟s communication programme entitled: 'The Perspective of the Patient'. The paper explores how strategic documents of the programme organize the communication work through situated displacements of the patient. Based on methodological...... elements from situational analysis (Clarke 2005) the analysis examines how the hospital‟s patient communication is not only about disease treatment, but rather about information treatment of the patient in order to attain a high level of patient satisfaction. The goal of patient satisfaction addresses both...

  16. Displacing the Patient

    Pors, Anja Svejgaard

    The analysis is based on an empirical study of a hospital’s communication strategy entitled: 'The Perspective of the Patient'. The paper asks how the strategy organizes communication work as situated displacements of the patient. Based on methodological elements from situational analysis (Clarke...... 2005) the analysis examines how the hospital’s patient communication is not just about disease treatment, but rather about information treatment of the patient in order to attain a high level of patient satisfaction. The goal of patient satisfaction addresses care-oriented understandings of the patient...

  17. Displaced patella fractures.

    Della Rocca, Gregory J


    Displaced patella fractures often result in disruption of the extensor mechanism of the knee. An intact extensor mechanism is a requirement for unassisted gait. Therefore, operative treatment of the displaced patella fracture is generally recommended. The evaluation of the patella fracture patient includes examination of extensor mechanism integrity. Operative management of patella fractures normally includes open reduction with internal fixation, although partial patellectomy is occasionally performed, with advancement of quadriceps tendon or patellar ligament to the fracture bed. Open reduction with internal fixation has historically been performed utilizing anterior tension band wiring, although comminution of the fracture occasionally makes this fixation construct inadequate. Supplementation or replacement of the tension band wire construct with interfragmentary screws, cerclage wire or suture, and/or plate-and-screw constructs may add to the stability of the fixation construct. Arthrosis of the patellofemoral joint is very common after healing of patella fractures, and substantial functional deficits may persist long after fracture healing has occurred. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  18. Lesion size in relation to ablation site during radiofrequency ablation

    Petersen, H H; Chen, X; Pietersen, A;


    convective cooling by induction of a flow around the electrode tip increases lesion dimensions and power consumptions. Furthermore we conclude that for the given target temperature the power consumption is positively correlated with lesion volume (p ...This study was designed to investigate the effect of the convective cooling of the tip of the ablation electrode during temperature controlled radiofrequency ablation. In vivo two different application sites in the left ventricle of anaesthetised pigs were ablated and in vitro ablation...... larger for septal applications than apical applications (p convective cooling by induction of flow yielded larger lesion volume, depth and width (p

  19. Variable displacement blower

    Bookout, Charles C.; Stotts, Robert E.; Waring, Douglass R.; Folsom, Lawrence R.


    A blower having a stationary casing for rotatably supporting a rotor assembly having a series of open ended chambers arranged to close against the surrounding walls of the casing. Pistons are slidably mounted within each chamber with the center of rotation of the pistons being offset in regard to the center of rotation of the rotor assembly whereby the pistons reciprocate in the chambers as the rotor assembly turns. As inlet port communicates with the rotor assembly to deliver a working substance into the chamber as the pistons approach a top dead center position in the chamber while an outlet port also communicates with the rotor to exhaust the working substance as the pistons approach a bottom dead center position. The displacement of the blower is varied by adjusting the amount of eccentricity between the center of rotation of the pistons and the center of rotation of the rotor assembly.

  20. Radiofrequency ablation of pulmonary tumors

    Crocetti, Laura, E-mail: l.crocetti@med.unipi.i [Division of Diagnostic Imaging and Intervention, Department of Liver Transplants, Hepatology and Infectious Diseases, Pisa University School of Medicine (Italy); Lencioni, Riccardo [Division of Diagnostic Imaging and Intervention, Department of Liver Transplants, Hepatology and Infectious Diseases, Pisa University School of Medicine (Italy)


    The development of image-guided percutaneous techniques for local tumor ablation has been one of the major advances in the treatment of solid tumors. Among these methods, radiofrequency (RF) ablation is currently established as the primary ablative modality at most institutions. RF ablation is accepted as the best therapeutic choice for patients with early-stage hepatocellular carcinoma when liver transplantation or surgical resection are not suitable options and is considered as a viable alternate to surgery for inoperable patients with limited hepatic metastatic disease, especially from colorectal cancer. Recently, RF ablation has been demonstrated to be a safe and valuable treatment option for patients with unresectable or medically inoperable lung malignancies. Resection should remain the standard therapy for non-small cell lung cancer (NSCLC) but RF ablation may be better than conventional external-beam radiation for the treatment of the high-risk individual with NSCLC. Initial favourable outcomes encourage combining radiotherapy and RF ablation, especially for treating larger tumors. In the setting of colorectal cancer lung metastases, survival rates provided by RF ablation in selected patients, are substantially higher than those obtained with any chemotherapy regimens and provide indirect evidence that RF ablation therapy improves survival in patients with limited lung metastatic disease.

  1. Displacement Parameter Inversion for a Novel Electromagnetic Underground Displacement Sensor

    Nanying Shentu


    Full Text Available Underground displacement monitoring is an effective method to explore deep into rock and soil masses for execution of subsurface displacement measurements. It is not only an important means of geological hazards prediction and forecasting, but also a forefront, hot and sophisticated subject in current geological disaster monitoring. In previous research, the authors had designed a novel electromagnetic underground horizontal displacement sensor (called the H-type sensor by combining basic electromagnetic induction principles with modern sensing techniques and established a mutual voltage measurement theoretical model called the Equation-based Equivalent Loop Approach (EELA. Based on that work, this paper presents an underground displacement inversion approach named “EELA forward modeling-approximate inversion method”. Combining the EELA forward simulation approach with the approximate optimization inversion theory, it can deduce the underground horizontal displacement through parameter inversion of the H-type sensor. Comprehensive and comparative studies have been conducted between the experimentally measured and theoretically inversed values of horizontal displacement under counterpart conditions. The results show when the measured horizontal displacements are in the 0–100 mm range, the horizontal displacement inversion discrepancy is generally tested to be less than 3 mm under varied tilt angles and initial axial distances conditions, which indicates that our proposed parameter inversion method can predict underground horizontal displacement measurements effectively and robustly for the H-type sensor and the technique is applicable for practical geo-engineering applications.

  2. Ablation of solids by femtosecond lasers ablation mechanism and ablation thresholds for metals and dielectrics

    Gamaly, E G; Tikhonchuk, V T; Luther-Davies, B


    The mechanism of ablation of solids by intense femtosecond laser pulses is described in an explicit analytical form. It is shown that at high intensities when the ionization of the target material is complete before the end of the pulse, the ablation mechanism is the same for both metals and dielectrics. The physics of this new ablation regime involves ion acceleration in the electrostatic field caused by charge separation created by energetic electrons escaping from the target. The formulae for ablation thresholds and ablation rates for metals and dielectrics, combining the laser and target parameters, are derived and compared to experimental data. The calculated dependence of the ablation thresholds on the pulse duration is in agreement with the experimental data in a femtosecond range, and it is linked to the dependence for nanosecond pulses.

  3. Measuring vulnerability to disaster displacement

    Brink, Susan A.; Khazai, Bijan; Power, Christopher; Wenzel, Friedemann


    Large scale disasters can cause devastating impacts in terms of population displacement. Between 2008 and 2013, on average 27 million people were displaced annually by disasters (Yonetani 2014). After large events such as hurricane Katrina or the Port-au-Prince earthquake, images of inadequate public shelter and concerns about large scale and often inequitable migration have been broadcast around the world. Population displacement can often be one of the most devastating and visible impacts of a natural disaster. Despite the importance of population displacement in disaster events, measures to understand the socio-economic vulnerability of a community often use broad metrics to estimate the total socio-economic risk of an event rather than focusing on the specific impacts that a community faces in a disaster. Population displacement is complex and multi-causal with the physical impact of a disaster interacting with vulnerability arising from the response, environmental issues (e.g., weather), cultural concerns (e.g., expectations of adequate shelter), and many individual factors (e.g., mobility, risk perception). In addition to the complexity of the causes, population displacement is difficult to measure because of the wide variety of different terms and definitions and its multi-dimensional nature. When we speak of severe population displacement, we may refer to a large number of displaced people, an extended length of displacement or associated difficulties such as poor shelter quality, risk of violence and crime in shelter communities, discrimination in aid, a lack of access to employment or other difficulties that can be associated with large scale population displacement. We have completed a thorough review of the literature on disaster population displacement. Research has been conducted on historic events to understand the types of negative impacts associated with population displacement and also the vulnerability of different groups to these impacts. We

  4. Ablation of solids by femtosecond lasers: ablation mechanism and ablation thresholds for metals and dielectrics

    Gamaly, E. G.; Rode, A. V.; Tikhonchuk, V. T.; Luther-Davies, B.


    The mechanism of ablation of solids by intense femtosecond laser pulses is described in an explicit analytical form. It is shown that at high intensities when the ionization of the target material is complete before the end of the pulse, the ablation mechanism is the same for both metals and dielectrics. The physics of this new ablation regime involves ion acceleration in the electrostatic field caused by charge separation created by energetic electrons escaping from the target. The formulae ...

  5. Point Coupled Displacement Sensor Project

    National Aeronautics and Space Administration — Real-time displacement measurement techniques are needed to acquire aerodynamic and structural system characteristics in flight. This proposal describes the...

  6. Displacement and resonance behaviors of a piezoelectric diaphragm driven by a double-sided spiral electrode

    Shen, Zhiyuan


    This paper presents the design of a lead zirconate titanate (PZT) diaphragm actuated by double-sided patterned electrodes. Au/Cr electrodes were deposited on bulk PZT wafers by sputtering while patterned by a lift-off process. SU-8 thick film was used to form the structural layer. Double-spiral electrode induced in-plane poling and piezoelectric elongation are converted to an out-of-plane displacement due to the confined boundary condition. The influence of different drive configurations and electrode parameters on deflection has been calculated by finite element methods (FEM) using a uniform field model. Impedance and quasi-static displacement spectra of the diaphragm were measured after poling. Adouble-sided patterned electrode diaphragm can be actuated by more drive configurations than a single-sided one. Compared with a single-sided electrode drive, a double-sided out-of-phase drive configuration increases the coupling coefficient of the fundamental resonance from 7.6% to 11.8%. The displacement response of the diaphragm increases from 2.6 to 8.6nmV 1. Configurations including the electric field component perpendicular to the poling direction can stimulate shear modes of the diaphragm. © 2012 IOP Publishing Ltd.

  7. Radiofrequency ablation of atrial fibrillation

    Wiesfeld, ACP; Tan, ES; Van Veldhuisen, DJ; Crijns, HJGM; Van Gelder, IC


    Twenty-five patients (16 males, mean age 46 years.) underwent radiofrequency ablation because of either paroxysmal (13 patients) or persistent atrial fibrillation (12 patients). Ablation aimed at earliest activation of spontaneous and catheter-induced repetitive ectopy in left and right atria and ap

  8. Laser ablation in analytical chemistry.

    Russo, Richard E; Mao, Xianglei; Gonzalez, Jhanis J; Zorba, Vassilia; Yoo, Jong


    In 2002, we wrote an Analytical Chemistry feature article describing the Physics of Laser Ablation in Microchemical Analysis. In line with the theme of the 2002 article, this manuscript discusses current issues in fundamental research, applications based on detecting photons at the ablation site (LIBS and LAMIS) and by collecting particles for excitation in a secondary source (ICP), and directions for the technology.

  9. Radiofrequency ablation of osteoid osteoma

    Vanderschueren, Geert Maria Joris Michael


    The main purpose of this thesis was to evaluate the effectiveness and safety of CT-guided radiofrequency ablation for the treatment of spinal and non-spinal osteoid osteomas. Furthermore, the technical requirements needed for safe radiofrequency ablation and the clinical outcome after radiofrequency

  10. Simulation of Pellet Ablation

    Parks, P. B.; Ishizaki, Ryuichi


    In order to clarify the structure of the ablation flow, 2D simulation is carried out with a fluid code solving temporal evolution of MHD equations. The code includes electrostatic sheath effect at the cloud interface.(P.B. Parks et al.), Plasma Phys. Contr. Fusion 38, 571 (1996). An Eulerian cylindrical coordinate system (r,z) is used with z in a spherical pellet. The code uses the Cubic-Interpolated Psudoparticle (CIP) method(H. Takewaki and T. Yabe, J. Comput. Phys. 70), 355 (1987). that divides the fluid equations into non-advection and advection phases. The most essential element of the CIP method is in calculation of the advection phase. In this phase, a cubic interpolated spatial profile is shifted in space according to the total derivative equations, similarly to a particle scheme. Since the profile is interpolated by using the value and the spatial derivative value at each grid point, there is no numerical oscillation in space, that often appears in conventional spline interpolation. A free boundary condition is used in the code. The possibility of a stationary shock will also be shown in the presentation because the supersonic ablation flow across the magnetic field is impeded.

  11. Dispossession and displacement in Libya

    Rhodri C Williams


    Full Text Available Inability to access pre-displacement housing, land and property poses a significant obstacle to the achievement of durable solutions for most IDPs in Libya. Displacement and dispossession cannot be separated from the legacy of the Gaddafi era.

  12. Displacement, Substitution, Sublimation: A Bibliography.

    Pedrini, D. T.; Pedrini, Bonnie C.

    Sigmund Freund worked with the mechanisms of displacement, substitution, and sublimation. These mechanisms have many similarities and have been studied diagnostically and therapeutically. Displacement and substitution seem to fit in well with phobias, hysterias, somatiyations, prejudices, and scapegoating. Phobias, prejudices, and scapegoating…

  13. Morphology and mechanisms of picosecond ablation of metal films on fused silica substrates

    Bass, Isaac L.; Negres, Raluca A.; Stanion, Ken; Guss, Gabe; Keller, Wesley J.; Matthews, Manyalibo J.; Rubenchik, Alexander M.; Yoo, Jae Hyuck; Bude, Jeffrey D.


    The ablation of magnetron sputtered metal films on fused silica substrates by a 1053 nm, picosecond class laser was studied as part of a demonstration of its use for in-situ characterization of the laser spot under conditions commonly used at the sample plane for laser machining and damage studies. Film thicknesses were 60 and 120 nm. Depth profiles and SEM images of the ablation sites revealed several striking and unexpected features distinct from those typically observed for ablation of bulk metals. Very sharp thresholds were observed for both partial and complete ablation of the films. Partial film ablation was largely independent of laser fluence with a surface smoothness comparable to that of the unablated surface. Clear evidence of material displacement was seen at the boundary for complete film ablation. These features were common to a number of different metal films including Inconel on commercial neutral density filters, stainless steel, and aluminum. We will present data showing the morphology of the ablation sites on these films as well as a model of the possible physical mechanisms producing the unique features observed.

  14. Real time ablation rate measurement during high aspect-ratio hole drilling with a 120-ps fiber laser.

    Mezzapesa, Francesco P; Sibillano, Teresa; Di Niso, Francesca; Ancona, Antonio; Lugarà, Pietro M; Dabbicco, Maurizio; Scamarcio, Gaetano


    We report on the instantaneous detection of the ablation rate as a function of depth during ultrafast microdrilling of metal targets. The displacement of the ablation front has been measured with a sub-wavelength resolution using an all-optical sensor based on the laser diode self-mixing interferometry. The time dependence of the laser ablation process within the depth of aluminum and stainless steel targets has been investigated to study the evolution of the material removal rate in high aspect-ratio micromachined holes.

  15. Magnetic and robotic navigation for catheter ablation: "joystick ablation".

    Ernst, Sabine


    Catheter ablation has become the treatment of choice to cure various arrhythmias in the last decades. The newest advancement of this general concept is made on the navigation ability using remote-controlled ablation catheters. This review summarizes the concept of the two currently available systems, followed by a critical review of the published clinical reports for each system, respectively. Despite the limited amount of data, an attempt to compare the two systems is made.


    Ivanka Juttner


    Full Text Available After primary oil recovery in reservoirs remains about 70% of unexploited oil. To improve the recovery of the remaining reserves, injection of a fluid provide the extra energy in a mchunical form. Oil displacement can he achieved by gas injection of lean natural gas, mainly methane, carbon dioxide etc. Oil displacement can be in immiscible or miscible conditions. This paper deals with mechanism of miscible gas drive. On the basis of simulation of the oil displacement process by gas injection into oil field Žutica the character of process, i. c. a degree of miscibility or immiscibility between the injected fluid and reservoir oil was determined.

  17. Field enhancement induced laser ablation

    Fiutowski, Jacek; Maibohm, Christian; Kjelstrup-Hansen, Jakob

    Sub-diffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures...

  18. Internal displacement in eastern Burma

    Heather Rae


    The history of post-independent Burma is characterisedby numerous conflicts in this extraordinarily heterogeneous country. Since military rule began in 196 2 Burmahas witnessed gross human rights abuses andmassive displacement.

  19. Internal displacement in eastern Burma

    Heather Rae


    Full Text Available The history of post-independent Burma is characterisedby numerous conflicts in this extraordinarily heterogeneous country. Since military rule began in 196 2 Burmahas witnessed gross human rights abuses andmassive displacement.

  20. To prevent or pursue displacement?


    The repertoire of survival actions of at-risk civilians includes bothavoiding and attempting displacement. But there are also overlaps,combinations and tacking back and forth between the two, whiletrying to mitigate the risks that any choice entails.

  1. Ablative Approaches for Pulmonary Metastases.

    Boyer, Matthew J; Ricardi, Umberto; Ball, David; Salama, Joseph K


    Pulmonary metastases are common in patients with cancer for which surgery is considered a standard approach in appropriately selected patients. A number of patients are not candidates for surgery due to a medical comorbidities or the extent of surgery required. For these patients, noninvasive or minimally invasive approaches to ablate pulmonary metastases are potential treatment strategies. This article summarizes the rationale and outcomes for non-surgical treatment approaches, including radiotherapy, radiofrequency and microwave ablation, for pulmonary metastases.

  2. Radiofrequency Ablation in Barrett's Esophagus

    Vani J.A. Konda


    Full Text Available Radiofrequency ablation (RFA is an endoscopic modality used in the treatment of Barrett's esophagus. RFA may be performed using a balloon-based catheter or using one of the probe catheters that attaches to the distal end of the endoscope. Here we demonstrate step-by-step instruction in using radiofrequency ablation in the treatment of Barrett's esophagus and highlight key concepts in the technique.

  3. Atrial fibrillation ablation using a closed irrigation radiofrequency ablation catheter.

    Golden, Keith; Mounsey, John Paul; Chung, Eugene; Roomiani, Pahresah; Morse, Michael Andew; Patel, Ankit; Gehi, Anil


    Catheter ablation is an effective therapy for symptomatic, medically refractory atrial fibrillation (AF). Open-irrigated radiofrequency (RF) ablation catheters produce transmural lesions at the cost of increased fluid delivery. In vivo models suggest closed-irrigated RF catheters create equivalent lesions, but clinical outcomes are limited. A cohort of 195 sequential patients with symptomatic AF underwent stepwise AF ablation (AFA) using a closed-irrigation ablation catheter. Recurrence of AF was monitored and outcomes were evaluated using Kaplan-Meier survival analysis and Cox proportional hazards models. Mean age was 59.0 years, 74.9% were male, 56.4% of patients were paroxysmal and mean duration of AF was 5.4 years. Patients had multiple comorbidities including hypertension (76.4%), tobacco abuse (42.1%), diabetes (17.4%), and obesity (mean body mass index 30.8). The median follow-up was 55.8 weeks. Overall event-free survival was 73.6% with one ablation and 77.4% after reablation (reablation rate was 8.7%). Median time to recurrence was 26.9 weeks. AF was more likely to recur in patients being treated with antiarrhythmic therapy at the time of last follow-up (recurrence rate 30.3% with antiarrhythmic drugs, 13.2% without antiarrhythmic drugs; hazard ratio [HR] 2.2, 95% confidence interval [CI] 1.1-4.4, P = 0.024) and in those with a history of AF greater than 2 years duration (HR 2.7, 95% CI 1.1-6.9, P = 0.038). Our study represents the largest cohort of patients receiving AFA with closed-irrigation ablation catheters. We demonstrate comparable outcomes to those previously reported in studies of open-irrigation ablation catheters. Given the theoretical benefits of a closed-irrigation system, a large head-to-head comparison using this catheter is warranted. ©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.

  4. Esophageal papilloma: Flexible endoscopic ablation byradiofrequency

    Gianmattia del Genio; Federica del Genio; Pietro Schettino; Paolo Limongelli; Salvatore Tolone; Luigi Brusciano; Manuela Avellino; Chiara Vitiello; Giovanni Docimo; Angelo Pezzullo; Ludovico Docimo


    Squamous papilloma of the esophagus is a rare benignlesion of the esophagus. Radiofrequency ablation is anestablished endoscopic technique for the eradication ofBarrett esophagus. No cases of endoscopic ablation ofesophageal papilloma by radiofrequency ablation (RFA)have been reported. We report a case of esophagealpapilloma successfully treated with a single sessionof radiofrequency ablation. Endoscopic ablation ofthe lesion was achieved by radiofrequency using anew catheter inserted through the working channelof endoscope. The esophageal ablated tissue wasremoved by a specifically designed cup. Completeablation was confirmed at 3 mo by endoscopy withbiopsies. This case supports feasibility and safety of asa new potential indication for BarrxTM RFA in patientswith esophageal papilloma.

  5. Displacement currents in geoelectromagnetic problems

    Mogilatov, Vladimir; Goldman, Mark; Persova, Marina; Soloveichik, Yury


    The influence of displacement currents in conventional geoelectromagnetic (GEM) methods using unimodal transversal electric (TE) or multimodal TE and TM (transversal magnetic) fields is only significant at very high frequencies in the frequency domain or at extremely early times in the time domain. The transient process in the latter includes three stages: the propagation through air, the propagation through earth and the diffusion within the earth. The influence of displacement currents is significant mainly during the former two stages, normally up to several tens to a few hundreds of nanoseconds. The behavior is essentially different in novel GEM methods using a vertical electric dipole (VED) or circular electric dipole (CED) sources of unimodal TM-fields. Under certain geoelectric conditions, the influence of displacement currents in these methods might be crucial at late times as well. This happens, if the model consists of insulating layers. In the absence of displacement currents, such layers would totally mask underlying structures. However, TM-fields including displacement currents depend on geoelectric parameters below insulating layers at late times.

  6. Femtosecond laser ablation of enamel

    Le, Quang-Tri; Bertrand, Caroline; Vilar, Rui


    The surface topographical, compositional, and structural modifications induced in human enamel by femtosecond laser ablation is studied. The laser treatments were performed using a Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs and 1030 nm) and fluences up to 14 J/cm2. The ablation surfaces were studied by scanning electron microscopy, grazing incidence x-ray diffraction, and micro-Raman spectroscopy. Regardless of the fluence, the ablation surfaces were covered by a layer of resolidified material, indicating that ablation is accompanied by melting of hydroxyapatite. This layer presented pores and exploded gas bubbles, created by the release of gaseous decomposition products of hydroxyapatite (CO2 and H2O) within the liquid phase. In the specimen treated with 1-kHz repetition frequency and 14 J/cm2, thickness of the resolidified material is in the range of 300 to 900 nm. The micro-Raman analysis revealed that the resolidified material contains amorphous calcium phosphate, while grazing incidence x-ray diffraction analysis allowed detecting traces of a calcium phosphate other than hydroxyapatite, probably β-tricalcium phosphate Ca3), at the surface of this specimen. The present results show that the ablation of enamel involves melting of enamel's hydroxyapatite, but the thickness of the altered layer is very small and thermal damage of the remaining material is negligible.

  7. Formation around planetary displaced orbit

    GONG Sheng-ping; LI Jun-feng; BAOYIN He-xi


    The paper investigates the relative motion around the planetary displaced orbit. Several kinds of displaced orbits for geocentric and martian cases were discussed. First, the relative motion was linearized around the displaced orbits. Then, two seminatural control laws were investigated for each kind of orbit and the stable regions were obtained for each case. One of the two control laws is the passive control law that is very attractive for engineering practice. However, the two control laws are not very suitable for the Martian mission. Another special semi-natural control law is designed based on the requirement of the Martian mission. The results show that large stable regions exist for the control law.

  8. Perceived Displacement explains Wolfpack Effect

    Matúš eŠimkovic


    Full Text Available We investigate the influence of perceived displacement of moving agent-like stimuli on the performance in dynamic interactive tasks. In order to reliably measure perceived displacement we utilize multiple tasks with different task demands. The perceived center of an agent’s body is displaced in the direction in which the agent is facing and this perceived displacement is larger than the theoretical position of the center of mass would predict. Furthermore, the displacement in the explicit judgment is dissociated from the displacement obtained by the implicit measures. By manipulating the location of the pivot point, we show that it is not necessary to postulate orientation as an additional cue utilized by perception, as has been suggested by earlier studies. These studies showed that the agent’s orientation influences the detection of chasing motion and the detection-related performance in interactive tasks. This influence has been labeled wolfpack effect. In one of the demonstrations of the wolfpack effect participants control a green circle on a display with a computer mouse. It has been shown that participants avoid display areas withagents pointing towards the green circle. Participants do so in favor of areas where the agents point in the direction perpendicular to the circle. We show that this avoidance behavior arises because the agent’s pivot point selected by the earlier studies is different from where people locate the center of agent’s body. As a consequence, the nominal rotation confounds rotation and translation. We show that the avoidance behavior disappears once the pivot point is set to the center of agent’s body.

  9. Displacement ventilation in lecture halls

    Egorov, Artem


    This thesis considers several important goals. The main purpose is to see how displacement ventilation sys-tem works in the lecture hall of M-building and compare obtained results with D2 and Indoor Climate Classi-fication. The second one is to analyze the function of the ventilation system. The last one is to realize when displacement ventilation is preferable to mixing ventilation. Analysis of the system was carried out with instruments from MUAS HVAC laboratory. In lecture hall were me...

  10. Displaced plaque in retroperitoneal adenopathy.

    Al-Okaili, Riyadh N; Schable, Stephen I; Marlow, Troy J


    This study was designed to determine when to consider incidental retroperitoneal masses on the basis of a displaced calcified atheromatous abdominal aorta on lateral radiographs. We did a retrospective review of 143 normal abdominal helical computed tomography scans of individuals aged 50 years and older to measure the distance between the posterior aortic wall and anterior cortex of vertebral bodies from T12 through L3. The normal abdominal aorta maintains a close relationship to the vertebral column. The distance should not be more than 10 mm in men and 7.3 mm in women. Displacement of aortic calcified atheroma greater than these distances should prompt a search for a retroperitoneal mass.

  11. Laser ablation studies of nanocomposites

    Oleg V. Mkrtychev


    Full Text Available The first experimental measurements of the threshold energy density values for the laser ablation of glass nanocomposites with nanodimensional coatings have been carried out under the action of the YAG–Nd laser power pulse radiation. The coatings in question were of different compositions and had been created by the sol–gel technology. The procedure for determining the laser ablation threshold energy density values was worked out on the base of the breakdown probability level of 0.5. The statistical processing of the measurement data over all the samples allowed obtaining the dependence of the ablation destruction threshold energy parameters on the coating physical and chemical properties such as the sample transmission in the visible region of the spectrum, coating thickness, the chemical composition of the film-forming solution, and on the pulse duration of laser radiation.

  12. CT imaging during microwave ablation: Analysis of spatial and temporal tissue contraction

    Liu, Dong; Brace, Christopher L., E-mail: [Departments of Radiology and Biomedical Engineering, University of Wisconsin, Madison, Wisconsin 53705 (United States)


    Purpose: To analyze the spatial distribution and temporal development of liver tissue contraction during high-temperature ablation by using intraprocedural computed tomography (CT) imaging. Methods: A total of 46 aluminum fiducial markers were positioned in a 60 × 45 mm grid, in a single plane, around a microwave ablation antenna in each of six ex vivo bovine liver samples. Ablations were performed for 10 min at 100 W. CT data of the liver sample were acquired every 30 s during ablation. Fiducial motion between acquisitions was tracked in postprocessing and used to calculate measures of tissue contraction and contraction rates. The spatial distribution and temporal evolution of contraction were analyzed. Results: Fiducial displacement indicated that the zone measured postablation was 8.2 ± 1.8 mm (∼20%) smaller in the radial direction and 7.1 ± 1.0 mm (∼10%) shorter in the longitudinal direction than the preablation tissue dimension. Therefore, the total ablation volume was reduced from its preablation value by approximately 45%. Very little longitudinal contraction was noted in the distal portion of the ablation zone. Central tissues contracted more than 60%, which was near an estimated limit of ∼70% based on initial water content. More peripheral tissues contracted only 15% in any direction. Contraction rates peaked during the first 60 s of heating with a roughly exponential decay over time. Conclusions: Ablation zones measured posttreatment are significantly smaller than the pretreatment tissue dimensions. Tissue contraction is spatially dependent, with the greatest effect occurring in the central ablation zone. Contraction rate peaks early and decays over time.

  13. Microwave ablation of hepatocellular carcinoma


    Although surgical resection is still the optimal treatmentoption for early-stage hepatocellular carcinoma(HCC) in patients with well compensated cirrhosis,thermal ablation techniques provide a valid nonsurgicaltreatment alternative, thanks to their minimalinvasiveness, excellent tolerability and safety profile,proven efficacy in local disease control, virtuallyunlimited repeatability and cost-effectiveness. Differentenergy sources are currently employed in clinics asphysical agents for percutaneous or intra-surgicalthermal ablation of HCC nodules. Among them, radiofrequency(RF) currents are the most used, whilemicrowave ablations (MWA) are becoming increasinglypopular. Starting from the 90s', RF ablation (RFA) rapidlybecame the standard of care in ablation, especially inthe treatment of small HCC nodules; however, RFAexhibits substantial performance limitations in thetreatment of large lesions and/or tumors located nearmajor heat sinks. MWA, first introduced in the FarEastern clinical practice in the 80s', showing promisingresults but also severe limitations in the controllabilityof the emitted field and in the high amount of poweremployed for the ablation of large tumors, resultingin a poor coagulative performance and a relativelyhigh complication rate, nowadays shows better resultsboth in terms of treatment controllability and of overallcoagulative performance, thanks to the improvementof technology. In this review we provide an extensiveand detailed overview of the key physical and technicalaspects of MWA and of the currently available systems,and we want to discuss the most relevant published dataon MWA treatments of HCC nodules in regard to clinicalresults and to the type and rate of complications, both inabsolute terms and in comparison with RFA.

  14. Transhemangioma Ablation of Hepatocellular Carcinoma

    Pua, Uei, E-mail: [Tan Tock Seng Hospital, Department of Diagnostic Radiology (Singapore)


    Radiofrequency ablation (RFA) is a well-established treatment modality in the treatment of early hepatocellular carcinoma (HCC) [1]. Safe trajectory of the RFA probe is crucial in decreasing collateral tissue damage and unwarranted probe transgression. As a percutaneous technique, however, the trajectory of the needle is sometimes constrained by the available imaging plane. The presence of a hemangioma beside an HCC is uncommon but poses the question of safety related to probe transgression. We hereby describe a case of transhemangioma ablation of a dome HCC.

  15. Displacement and difference in Lubumbashi

    Aurelia Wa Kabwe-Segatti


    Full Text Available Signs on the outskirts of the second largest city in the Democratic Republic of Congo (DRC welcome visitors to ‘the city of peace’. Lubumbashi has a reputation as a haven of tolerance in a violent nation but how are displaced people treated?

  16. To prevent or pursue displacement?

    Casey Barrs


    Full Text Available The repertoire of survival actions of at-risk civilians includes bothavoiding and attempting displacement. But there are also overlaps,combinations and tacking back and forth between the two, whiletrying to mitigate the risks that any choice entails.




    A research effort was undertaken to determine the need for any changes to USNRC's seismic regulatory practice to reflect the move, in the earthquake engineering community, toward using expected displacement rather than force (or stress) as the basis for assessing design adequacy. The research explored the extent to which displacement based seismic design methods, such as given in FEMA 273, could be useful for reviewing nuclear power stations. Two structures common to nuclear power plants were chosen to compare the results of the analysis models used. The first structure is a four-story frame structure with shear walls providing the primary lateral load system, referred herein as the shear wall model. The second structure is the turbine building of the Diablo Canyon nuclear power plant. The models were analyzed using both displacement based (pushover) analysis and nonlinear dynamic analysis. In addition, for the shear wall model an elastic analysis with ductility factors applied was also performed. The objectives of the work were to compare the results between the analyses, and to develop insights regarding the work that would be needed before the displacement based analysis methodology could be considered applicable to facilities licensed by the NRC. A summary of the research results, which were published in NUREGICR-6719 in July 2001, is presented in this paper.

  18. Ablation of Solid Hydrogen in a Plasma

    Jørgensen, L. W.; Sillesen, Alfred Hegaard


    Several hydrogen pellet ablation models based on the formation of a shielding neutral cloud have been reported by different authors. The predicted ablation rates are shown to follow almost the same scaling law and this is used to explain the authors' ablation experiment....

  19. Soft thrombus formation in radiofrequency catheter ablation

    Demolin, JM; Eick, OJ; Munch, K; Koullick, E; Nakagawa, H; Wittkampf, FHM


    During RF catheter ablation, local temperature elevation can result in coagulum formation on the ablation electrode, resulting in impedance rise. A recent study has also demonstrated the formation of a so-called soft thrombus during experimental ablations. This deposit poorly adhered to the catheter

  20. Catheter ablation of parahisian premature ventricular complex.

    Kim, Jun; Kim, Jeong Su; Park, Yong Hyun; Kim, June Hong; Chun, Kook Jin


    Catheter ablation is performed in selected patients with a symptomatic premature ventricular complex (PVC) or PVC-induced cardiomyopathy. Ablation of PVC from the His region has a high risk of inducing a complete atrioventricular block. Here we report successful catheter ablation of a parahisian PVC in a 63-year-old man.

  1. Laser ablation at the hydrodynamic regime

    Gojani Ardian B.


    Full Text Available Laser ablation of several metals and PVC polymer by high energy nanosecond laser pulses is investigated experimentaly. Visualization by shadowgraphy revealed the dynamics of the discontinuities in ambient air and ablation plume above the target surface, while surface profiling allowed for determination of the ablated mass.

  2. Laser ablation at the hydrodynamic regime

    Gojani Ardian B.


    Laser ablation of several metals and PVC polymer by high energy nanosecond laser pulses is investigated experimentaly. Visualization by shadowgraphy revealed the dynamics of the discontinuities in ambient air and ablation plume above the target surface, while surface profiling allowed for determination of the ablated mass.

  3. Laser ablation and optical surface damage

    Chase, L. L.; Hamza, A. V.; Lee, H. W. H.

    Laser ablation usually accompanies optical surface damage to bare surfaces and coatings. Investigations of optical damage mechanisms by observation of ablation processes at laser fluences very close to the optical damage threshold are described. Several promising surface characterization methods for investigating damage mechanisms are also described. The possible role of laser ablation in initiating or promoting optical surface damage is discussed.

  4. Laser ablation mechanisms and optical surface damage

    Chase, L. L.; Hamza, A. V.; Lee, H. W. H.


    Laser ablation usually accompanies optical surface damage to bare surfaces and coatings. Investigations of optical damage mechanisms by observation of ablation processes at laser fluences very close to the optical damage threshold are described. Several promising surface characterization methods for investigating damage mechanisms are also described. The possible role of laser ablation in initiating or promoting optical surface damage is discussed.

  5. Nanosecond laser ablation of bulk Al, Bronze, and Cu: ablation rate saturation and laserinduced oxidation

    R. Maisterrena-Epstein; S. Camacho-López; L. Escobar-Alarcón; M. A. Camacho-López


    In this work we report about the characteristics of nanosecond laser ablation, in atmospheric air, of bulk Al, Bronze, and Cu. Average per pulse laser ablation rate and its dependence on ablation depth is presented for these three metals. We will demonstrate and discuss some distinctive features of the ablation saturation effect of the above metals. We will also present results on laser-induced oxidation of the metals which results off the ablation event. We studied the laser-induced oxidatio...

  6. Harmonic motion imaging for abdominal tumor detection and high-intensity focused ultrasound ablation monitoring: an in vivo feasibility study in a transgenic mouse model of pancreatic cancer.

    Chen, Hong; Hou, Gary Y; Han, Yang; Payen, Thomas; Palermo, Carmine F; Olive, Kenneth P; Konofagou, Elisa E


    Harmonic motion imaging (HMI) is a radiationforce- based elasticity imaging technique that tracks oscillatory tissue displacements induced by sinusoidal ultrasonic radiation force to assess the resulting oscillatory displacement denoting the underlying tissue stiffness. The objective of this study was to evaluate the feasibility of HMI in pancreatic tumor detection and high-intensity focused ultrasound (HIFU) treatment monitoring. The HMI system consisted of a focused ultrasound transducer, which generated sinusoidal radiation force to induce oscillatory tissue motion at 50 Hz, and a diagnostic ultrasound transducer, which detected the axial tissue displacements based on acquired radio-frequency signals using a 1-D cross-correlation algorithm. For pancreatic tumor detection, HMI images were generated for pancreatic tumors in transgenic mice and normal pancreases in wild-type mice. The obtained HMI images showed a high contrast between normal and malignant pancreases with an average peak-to-peak HMI displacement ratio of 3.2. Histological analysis showed that no tissue damage was associated with HMI when it was used for the sole purpose of elasticity imaging. For pancreatic tumor ablation monitoring, the focused ultrasound transducer was operated at a higher acoustic power and longer pulse length than that used in tumor detection to simultaneously induce HIFU thermal ablation and oscillatory tissue displacements, allowing HMI monitoring without interrupting tumor ablation. HMI monitoring of HIFU ablation found significant decreases in the peak-to-peak HMI displacements before and after HIFU ablation with a reduction rate ranging from 15.8% to 57.0%. The formation of thermal lesions after HIFU exposure was confirmed by histological analysis. This study demonstrated the feasibility of HMI in abdominal tumor detection and HIFU ablation monitoring.

  7. Interplay between interstitial displacement and displacive lattice transformations

    Zhang, Xie; Hickel, Tilmann; Rogal, Jutta; Neugebauer, Jörg


    Diffusionless displacive lattice rearrangements, which include martensitic transformations, are in real materials often accompanied by a displacive drag of interstitials. The interplay of both processes leads to a particular atomistic arrangement of the interstitials in the product phase, which is decisive for its performance. An archetype example is the martensitic transformation in Fe-C alloys. One of the puzzles for this system is that the deviation from the cubic symmetry (i.e., the tetragonality) in the martensite resulting from this interplay is lower than what thermodynamics dictates. In our ab initio approach, the relative motion of C in the transforming lattice is studied with the nudged elastic band method. We prove that an atomic shearlike shuffle mechanism of adjacent (11 2 ¯) Fe layers along the ±[111] bcc directions is essential to achieve a redistribution of C atoms during the fcc → bcc transition, which fully explains the abnormal behavior. Furthermore, the good agreement with experiment validates our method to treat a diffusionless redistribution of interstitials and a displacive rearrangement of the host lattice simultaneously.

  8. Photochemical Ablation of Organic Solids

    Garrison, Barbara


    As discovered by Srinivasan in 1982, irradiation of materials by far UV laser light can lead to photochemical ablation, a process distinct from normal thermal ablation in which the laser primarily heats the material. A versatile mesoscopic model for molecular dynamics simulations of the laser ablation phenomena is presented. The model incorporates both the thermal and photochemical events, that is, both heating of the system and UV induced bond-cleavage followed by abstraction and radical-radical recombination reactions. The results from the simulations are compared to experimental data and the basic physics and chemistry for each irradiation regime are discussed. Initial results from polymer ablation simulations will be presented. L. V. Zhigilei, P. B. S. Kodali and B. J. Garrison, J. Phys. Chem. B, 102, 2845-2853 (1998); L. V. Zhigilei and B. J. Garrison, Journal of Applied Physics, 88, 1281-1298 (2000). Y. G. Yingling, L. V. Zhigilei and B. J. Garrison, J. Photochemistry and Photobiology A: Chemistry, 145, 173-181 (2001); Y. G. Yingling and B. J. Garrison, Chem. Phys. Lett., 364, 237-243 (2002).

  9. Catheter ablation - new developments in robotics.

    Chun, K R Julian; Schmidt, Boris; Köktürk, Bülent; Tilz, Roland; Fürnkranz, Alexander; Konstantinidou, Melanie; Wissner, Erik; Metzner, Andreas; Ouyang, Feifan; Kuck, Karl-Heinz


    Catheter ablation has become the curative treatment modality for various arrhythmias. Extending the indications for catheter ablation from simple supraventricular tachycardias to complex arrhythmias such as ventricular tachycardia or atrial fibrillation, the investigator faces prolonged procedure times, fluoroscopy exposure and the need for stable and reproducible catheter movement. Recently, remote-controlled robotic catheter ablation has emerged as a novel ablation concept to meet these requirements. This review describes the two available robotic ablation systems and summarizes their clinical applications and current human experience.

  10. Hydrodynamic instabilities in an ablation front

    Piriz, A R; Portugues, R F [E.T.S.I. Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain)


    The hydrodynamic stability of an ablation front is studied for situations in which the wavelength of the perturbations is larger than the distance to the critical surface where the driving radiation is absorbed. An analytical model is presented, and it shows that under conditions in which the thermal flux is limited within the supercritical region of the ablative corona, the front may behave like a flame or like an ablation front, depending on the perturbation wavelength. For relatively long wavelengths the critical and ablation surfaces practically lump together into a unique surface and the front behaves like a flame, whereas for the shortest wavelengths the ablation front substructure is resolved.

  11. The effect of temperature dependent tissue parameters on acoustic radiation force induced displacements

    Suomi, Visa; Han, Yang; Konofagou, Elisa; Cleveland, Robin O.


    Multiple ultrasound elastography techniques rely on acoustic radiation force (ARF) in monitoring high-intensity focused ultrasound (HIFU) therapy. However, ARF is dependent on tissue attenuation and sound speed, both of which are also known to change with temperature making the therapy monitoring more challenging. Furthermore, the viscoelastic properties of tissue are also temperature dependent, which affects the displacements induced by ARF. The aim of this study is to quantify the temperature dependent changes in the acoustic and viscoelastic properties of liver and investigate their effect on ARF induced displacements by using both experimental methods and simulations. Furthermore, the temperature dependent viscoelastic properties of liver are experimentally measured over a frequency range of 0.1-200 Hz at temperatures reaching 80 °C, and both conventional and fractional Zener models are used to fit the data. The fractional Zener model was found to fit better with the experimental viscoelasticity data with respect to the conventional model with up to two orders of magnitude lower sum of squared errors (SSE). The characteristics of experimental displacement data were also seen in the simulations due to the changes in attenuation coefficient and lesion development. At low temperatures before thermal ablation, attenuation was found to affect the displacement amplitude. At higher temperature, the decrease in displacement amplitude occurs approximately at 60-70 °C due to the combined effect of viscoelasticity changes and lesion growth overpowering the effect of attenuation. The results suggest that it is necessary to monitor displacement continuously during HIFU therapy in order to ascertain when ablation occurs.

  12. Single-mode displacement sensor

    Duivenvoorden, Kasper; Terhal, Barbara M.; Weigand, Daniel


    We show that one can determine both parameters of a displacement acting on an oscillator with an accuracy which scales inversely with the square root of the number of photons in the oscillator. Our results are obtained by using a grid state as a sensor state for detecting small translations in phase space (displacements). Grid states were first proposed [D. Gottesman et al., Phys. Rev. A 64, 012310 (2001), 10.1103/PhysRevA.64.012310] for encoding a qubit into an oscillator: an efficient preparation protocol of such states, using a coupling to a qubit, was later developed [B. M. Terhal and D. Weigand, Phys. Rev. A 93, 012315 (2016), 10.1103/PhysRevA.93.012315]. We compare the performance of the grid state with the quantum compass or cat code state and place our results in the context of the two-parameter quantum Cramér-Rao lower bound on the variances of the displacement parameters. We show that the accessible information about the displacement for a grid state increases with the number of photons in the state when we measure and prepare the state using a phase estimation protocol. This is in contrast with the accessible information in the quantum compass state which we show is always upper bounded by a constant, independent of the number of photons. We present numerical simulations of a phase estimation based preparation protocol of a grid state in the presence of photon loss, nonlinearities, and qubit measurement, using no post-selection, showing how the two effective squeezing parameters which characterize the grid state change during the preparation. The idea behind the phase estimation protocol is a simple maximal-information gain strategy.

  13. Internal Displaced People i Colombia

    Gustafsen, Rune Rud


    This thesis investigates weather or not the formation and consolidation of peace communities in rural Colombia represent an alternative in the Internal Displaced People´s (IDP) search for sustainable livelihoods in a context highly influenced by on one hand the waging war between primarily FARC and the Colombian state and on the other the violent consequences of the evolved drug production which is influencing all levels of Colombian society. The IDP population in Colombia is according to ...

  14. Microstructure and properties of W-ZrC composites prepared by the displacive compensation of porosity (DCP) method

    Zhang Shouming, E-mail: [Key Lab of Advanced Ceramic Fibers and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, DeYa Road, Changsha 410073 (China); Wang Song; Li Wei; Zhu Yulin; Chen Zhaohui [Key Lab of Advanced Ceramic Fibers and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, DeYa Road, Changsha 410073 (China)


    Highlights: > Microstructure of the W-ZrC composites was investigated using TEM and SEAD. > Mechanical properties of the composites were measured. > Ablation resistance was researched. - Abstract: Tungsten-zirconium carbide composites were fabricated at different temperatures by the displacive compensation of porosity (DCP) method, the microstructure, mechanical properties, and ablation resistance were investigated. It was found that no WC phase was left in the composites prepared at 1400 deg. C, and a few residual W{sub 2}C particles were surrounded in W product. Microstructure analyses revealed that zirconium atoms diffused into tungsten carbide to form ZrC and W{sub 2}Zr besides carbon diffused into the Zr{sub 2}Cu melt. Composites fabricated at 1400 deg. C had a flexural strength of 356.7 {+-} 15.2 MPa, an elastic modulus of 193.7 {+-} 9.8 GPa, a fracture toughness of 7.0 {+-} 0.7 MPa m{sup 1/2}, and a hardness of 13.6 {+-} 0.7 GPa. After ablated by an oxyacetylene flame for 30 s, the higher temperature prepared composites had a better ablation resistance, the linear ablation rate was 0.0033 {+-} 0.0004 mm/s, and the mass ablation rate was 0.0012 {+-} 0.0001 g/s.

  15. Glue septal ablation: A promising alternative to alcohol septal ablation

    Sercan Okutucu


    Full Text Available Hypertrophic cardiomyopathy (HCM is defined as myocardial hypertrophy in the absence of another cardiac or systemic disease capable of producing the magnitude of present hypertrophy. In about 70% of patients with HCM, there is left ventricular outflow tract (LVOT obstruction (LVOTO and this is known as obstructive type of hypertrophic cardiomyopathy (HOCM. Cases refractory to medical treatment have had two options either surgical septal myectomy or alcohol septal ablation (ASA to alleviate LVOT gradient. ASA may cause some life-threatening complications including conduction disturbances and complete heart block, hemodynamic compromise, ventricular arrhythmias, distant and massive myocardial necrosis. Glue septal ablation (GSA is a promising technique for the treatment of HOCM. Glue seems to be superior to alcohol due to some intrinsic advantageous properties of glue such as immediate polymerization which prevents the leak into the left anterior descending coronary artery and it is particularly useful in patients with collaterals to the right coronary artery in whom alcohol ablation is contraindicated. In our experience, GSA is effective and also a safe technique without significant complications. GSA decreases LVOT gradient immediately after the procedure and this reduction persists during 12 months of follow-up. It improves New York Heart Association functional capacity and decrease interventricular septal wall thickness. Further studies are needed in order to assess the long-term efficacy and safety of this technique.

  16. Laser Ablation Propulsion A Study

    Irfan, Sayed A.; Ugalatad, Akshata C.

    Laser Ablation Propulsion (LAP) will serve as an alternative propulsion system for development of microthrusters. The principle of LAP is that when a laser (pulsed or continuous wave) with sufficient energy (more than the vaporization threshold energy of material) is incident on material, ablation or vaporization takes place which leads to the generation of plasma. The generated plasma has the property to move away from the material hence pressure is generated which leads to the generation of thrust. Nowadays nano satellites are very common in different space and defence applications. It is important to build micro thruster which are useful for orienting and re-positioning small aircraft (like nano satellites) above the atmosphere. modelling of LAP using MATLAB and Mathematica. Schematic is made for the suitable optical configuration of LAP. Practical experiments with shadowgraphy and self emission techniques and the results obtained are analysed taking poly (vinyl-chloride) (PVC) as propellant to study the

  17. 25 CFR 700.59 - Displaced person.


    ... 25 Indians 2 2010-04-01 2010-04-01 false Displaced person. 700.59 Section 700.59 Indians THE OFFICE OF NAVAJO AND HOPI INDIAN RELOCATION COMMISSION OPERATIONS AND RELOCATION PROCEDURES General Policies and Instructions Definitions § 700.59 Displaced person. Displaced person means a member of...

  18. Simplified method for esophagus protection during radiofrequency catheter ablation of atrial fibrillation - prospective study of 704 cases

    José Carlos Pachón Mateos


    Full Text Available AbstractIntroduction:Although rare, the atrioesophageal fistula is one of the most feared complications in radiofrequency catheter ablation of atrial fibrillation due to the high risk of mortality.Objective:This is a prospective controlled study, performed during regular radiofrequency catheter ablation of atrial fibrillation, to test whether esophageal displacement by handling the transesophageal echocardiography transducer could be used for esophageal protection.Methods:Seven hundred and four patients (158 F/546M [22.4%/77.6%]; 52.8±14 [17-84] years old, with mean EF of 0.66±0.8 and drug-refractory atrial fibrillation were submitted to hybrid radiofrequency catheter ablation (conventional pulmonary vein isolation plus AF-Nests and background tachycardia ablation with displacement of the esophagus as far as possible from the radiofrequency target by transesophageal echocardiography transducer handling. The esophageal luminal temperature was monitored without and with displacement in 25 patients.Results:The mean esophageal displacement was 4 to 9.1cm (5.9±0.8 cm. In 680 of the 704 patients (96.6%, it was enough to allow complete and safe radiofrequency delivery (30W/40ºC/irrigated catheter or 50W/60ºC/8 mm catheter without esophagus overlapping. The mean esophageal luminal temperature changes with versus without esophageal displacement were 0.11±0.13ºC versus 1.1±0.4ºC respectively, P<0.01. The radiofrequency had to be halted in 68% of the patients without esophageal displacement because of esophageal luminal temperature increase. There was no incidence of atrioesophageal fistula suspected or confirmed. Only two superficial bleeding caused by transesophageal echocardiography transducer insertion were observed.Conclusion:Mechanical esophageal displacement by transesophageal echocardiography transducer during radiofrequency catheter ablation was able to prevent a rise in esophageal luminal temperature, helping to avoid esophageal thermal


    QiuWei; KangYilan; SunQingchi; QinQinghua; LinYu


    Multilayer piezoelectric ceramic displacement actuators are susceptible to cracking in the region near the edge of the internal electrode, which may cause system damage or failure.In this paper, the stress distribution of a multilayer piezoelectric composite is investigated in a working environment and the optimized geometrical configuration of the piezoelectric layer is obtained. The stress distribution in the structure and the stress concentration near the edge of the internal electrode, induced by non-uniform electric field distribution, are analyzed by moirá interferometry experiment and finite element numerical simulation. Based on the above analysis,two optimized geometrical models are presented for the purpose of geometrical configuration selection, with which stress concentration can be reduced significantly while the feasibility of the machining process and the basic structural functions occurring in the conventional model are retained. The numerical results indicate that the maximum stress in the optimized models is effectively diminished compared to the conventional model. For instance, the peak value of the principal stress in the optimized model Ⅱ is 93.1% smaller than that in the conventional model.It is proved that stress concentration can be effectively relaxed in the latter of the two optimized models and thus the probability of fracture damage can be decreased.

  20. High-resolution monitoring of the hole depth during ultrafast laser ablation drilling by diode laser self-mixing interferometry.

    Mezzapesa, Francesco P; Ancona, Antonio; Sibillano, Teresa; De Lucia, Francesco; Dabbicco, Maurizio; Lugarà, Pietro Mario; Scamarcio, Gaetano


    We demonstrate that diode laser self-mixing interferometry can be exploited to instantaneously measure the ablation front displacement and the laser ablation rate during ultrafast microdrilling of metals. The proof of concept was obtained using a 50-μm-thick stainless steel plate as the target, a 120 ps/110 kHz microchip fiber laser as the machining source, and an 823 nm diode laser with an integrated photodiode as the probe. The time dependence of the hole penetration depth was measured with a 0.41 µm resolution.

  1. Transient Ablation Regime in Circuit Breakers

    Alexandre MARTIN; Jean-Yves TREPANIER; Marcelo REGGIO; GUO Xue-yan


    Nozzle wall ablation caused by high temperature electric arcs is studied in the context of high voltage SF6 circuit breakers.The simplified ablation model used in litterature has been updated to take into account the unsteady state of ablation.Ablation rate and velocity are now calculated by a kinetic model using two layers of transition,between the bulk plasma and the ablating wall.The first layer (Knudsen layer),right by the wall,is a kinetic layer of a few mean-free path of thickness.The second layer is collision dominated and makes the transition between the kinetic layer and the plasma bulk.With this new coupled algorithm,it is now possible to calculate the temperature distribution inside the wall,as well as more accurate ablation rates.

  2. Computer-aided hepatic tumour ablation

    Voirin, D; Amavizca, M; Leroy, A; Letoublon, C; Troccaz, J; Voirin, David; Payan, Yohan; Amavizca, Miriam; Leroy, Antoine; Letoublon, Christian; Troccaz, Jocelyne


    Surgical resection of hepatic tumours is not always possible. Alternative techniques consist in locally using chemical or physical agents to destroy the tumour and this may be performed percutaneously. It requires a precise localisation of the tumour placement during ablation. Computer-assisted surgery tools may be used in conjunction to these new ablation techniques to improve the therapeutic efficiency whilst benefiting from minimal invasiveness. This communication introduces the principles of a system for computer-assisted hepatic tumour ablation.

  3. Neocuproine Ablates Melanocytes in Adult Zebrafish

    O'Reilly-Pol, Thomas; Johnson, Stephen L.


    The simplest regeneration experiments involve the ablation of a single cell type. While methods exist to ablate the melanocytes of the larval zebrafish,1,2 no convenient method exists to ablate melanocytes in adult zebrafish. Here, we show that the copper chelator neocuproine (NCP) causes fragmentation and disappearance of melanin in adult zebrafish melanocytes. Adult melanocytes expressing eGFP under the control of a melanocyte-specific promoter also lose eGFP fluorescence in the presence of...

  4. Displacement of squeezed propagating microwave states

    Fedorov, Kirill G.; Zhong, Ling; Pogorzalek, Stefan; Eder, Peter; Fischer, Michael; Goetz, Jan; Wulschner, Friedrich; Xie, Edwar; Menzel, Edwin; Deppe, Frank; Marx, Achim; Gross, Rudolf

    Displacement of propagating squeezed states is a fundamental operation for quantum communications. It can be applied to fundamental studies of macroscopic quantum coherence and has an important role in quantum teleportation protocols with propagating microwaves. We generate propagating squeezed states using a Josephson parametric amplifier and implement displacement using a cryogenic directional coupler. We study single- and two-mode displacement regimes. For the single-mode displacement we find that the squeezing level of the displaced squeezed state does not depend on the displacement amplitude. Also, we observe that quantum entanglement between two spatially separated channels stays constant across 4 orders of displacement power. We acknowledge support by the German Research Foundation through SFB 631 and FE 1564/1-1, the EU project PROMISCE, and Elite Network of Bavaria through the program ExQM.

  5. Resonant neutron-induced atomic displacements

    Elmaghraby, Elsayed K.


    A model for displacement cascade function was modified to account for the continuous variation of displacement density in the material in response to neutron exposure. The model is based on the Gaussian distribution of displacement energies of atoms in a material. Analytical treatment for moderated epithermal neutron field was given in which the displacement density was divided into two terms, discrete-resonance term and continuum term. Calculation are done for all isotopes using ENDF/B VII.1 data files and temperature dependent cross section library. Weighted elemental values were reported a fitting was performed to obtain energy-dependent formula of displacement density and reduce the number of parameters. Results relevant the present specification of the cascade function are tabulated for each element to enable calculation of displacement density at any value of displacement energy in the between 5 eV and 55 eV.

  6. Cryoballoon Catheter Ablation in Atrial Fibrillation

    Cevher Ozcan


    Full Text Available Pulmonary vein isolation with catheter ablation is an effective treatment in patients with symptomatic atrial fibrillation refractory or intolerant to antiarrhythmic medications. The cryoballoon catheter was recently approved for this procedure. In this paper, the basics of cryothermal energy ablation are reviewed including its ability of creating homogenous lesion formation, minimal destruction to surrounding vasculature, preserved tissue integrity, and lower risk of thrombus formation. Also summarized here are the publications describing the clinical experience with the cryoballoon catheter ablation in both paroxysmal and persistent atrial fibrillation, its safety and efficacy, and discussions on the technical aspect of the cryoballoon ablation procedure.

  7. Aromatic Thermosetting Copolyesters for Ablative TPS Project

    National Aeronautics and Space Administration — Better performing ablative thermal protection systems than currently available are needed to satisfy requirements of the most severe crew exploration vehicles, such...

  8. The atrial fibrillation ablation pilot study

    Arbelo, Elena; Brugada, Josep; Hindricks, Gerhard


    AIMS: The Atrial Fibrillation Ablation Pilot Study is a prospective registry designed to describe the clinical epidemiology of patients undergoing an atrial fibrillation (AFib) ablation, and the diagnostic/therapeutic processes applied across Europe. The aims of the 1-year follow-up were to analyse...... tachycardia, and 4 patients died (1 haemorrhagic stroke, 1 ventricular fibrillation in a patient with ischaemic heart disease, 1 cancer, and 1 of unknown cause). CONCLUSION: The AFib Ablation Pilot Study provided crucial information on the epidemiology, management, and outcomes of catheter ablation of AFib...

  9. Femtosecond ultraviolet laser ablation of silver and comparison with nanosecond ablation

    Christensen, Bo Toftmann; Doggett, B.; Budtz-Jørgensen, C.


    The ablation plume dynamics arising from ablation of silver with a 500 fs, 248 nm laser at ~2 J cm-2 has been studied using angle-resolved Langmuir ion probe and thin film deposition techniques. For the same laser fluence, the time-of-flight ion signals from femtosecond and nanosecond laser ablat...

  10. A Theoretical Model to Predict Both Horizontal Displacement and Vertical Displacement for Electromagnetic Induction-Based Deep Displacement Sensors

    Xiong Li


    Full Text Available Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA has been proposed to quantitatively depict II-type sensors’ mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors’ monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency.

  11. A theoretical model to predict both horizontal displacement and vertical displacement for electromagnetic induction-based deep displacement sensors.

    Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong


    Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type) to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA) to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA) has been proposed to quantitatively depict II-type sensors' mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors' monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency.

  12. Analysis of iodinated contrast delivered during thermal ablation: is material trapped in the ablation zone?

    Wu, Po-hung; Brace, Chris L.


    Intra-procedural contrast-enhanced CT (CECT) has been proposed to evaluate treatment efficacy of thermal ablation. We hypothesized that contrast material delivered concurrently with thermal ablation may become trapped in the ablation zone, and set out to determine whether such an effect would impact ablation visualization. CECT images were acquired during microwave ablation in normal porcine liver with: (A) normal blood perfusion and no iodinated contrast, (B) normal perfusion and iodinated contrast infusion or (C) no blood perfusion and residual iodinated contrast. Changes in CT attenuation were analyzed from before, during and after ablation to evaluate whether contrast was trapped inside of the ablation zone. Visualization was compared between groups using post-ablation contrast-to-noise ratio (CNR). Attenuation gradients were calculated at the ablation boundary and background to quantitate ablation conspicuity. In Group A, attenuation decreased during ablation due to thermal expansion of tissue water and water vaporization. The ablation zone was difficult to visualize (CNR  =  1.57  ±  0.73, boundary gradient  =  0.7  ±  0.4 HU mm-1), leading to ablation diameter underestimation compared to gross pathology. Group B ablations saw attenuation increase, suggesting that iodine was trapped inside the ablation zone. However, because the normally perfused liver increased even more, Group B ablations were more visible than Group A (CNR  =  2.04  ±  0.84, boundary gradient  =  6.3  ±  1.1 HU mm-1) and allowed accurate estimation of the ablation zone dimensions compared to gross pathology. Substantial water vaporization led to substantial attenuation changes in Group C, though the ablation zone boundary was not highly visible (boundary gradient  =  3.9  ±  1.1 HU mm-1). Our results demonstrate that despite iodinated contrast being trapped in the ablation zone, ablation visibility was

  13. Displaceable Gear Torque Controlled Driver

    Cook, Joseph S., Jr. (Inventor)


    Methods and apparatus are provided for a torque driver including a displaceable gear to limit torque transfer to a fastener at a precisely controlled torque limit. A biasing assembly biases a first gear into engagement with a second gear for torque transfer between the first and second gear. The biasing assembly includes a pressurized cylinder controlled at a constant pressure that corresponds to a torque limit. A calibrated gage and valve is used to set the desired torque limit. One or more coiled output linkages connect the first gear with the fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. The torque limit is adjustable and may be different for fasteners within the same fastener configuration.




    The USNRC has initiated a project to determine if any of the likely revisions to traditional earthquake engineering practice are relevant to seismic design of the specialized structures, systems and components of nuclear power plants and of such significance to suggest that a change in design practice might be warranted. As part of the initial phase of this study, a literature survey was conducted on the recent changes in seismic design codes/standards, on-going activities of code-writing organizations/communities, and published documents on displacement-based design methods. This paper provides a summary of recent changes in building codes and on-going activities for future codes. It also discusses some technical issues for further consideration.

  15. Displacement Based Seismic Design Criteria

    Costello, J.F.; Hofmayer, C.; Park, Y.J.


    The USNRC has initiated a project to determine if any of the likely revisions to traditional earthquake engineering practice are relevant to seismic design of the specialized structures, systems and components of nuclear power plants and of such significance to suggest that a change in design practice might be warranted. As part of the initial phase of this study, a literature survey was conducted on the recent changes in seismic design codes/standards, on-going activities of code-writing organizations/communities, and published documents on displacement-based design methods. This paper provides a summary of recent changes in building codes and on-going activities for future codes. It also discusses some technical issues for further consideration.

  16. Catheter ablation for atrial fibrillation after an unsuccessful surgical ablation and biological prosthetic mitral valve replacement: A pilot study

    Sergey E. Mamchur


    Conclusion: Catheter ablation is an effective method for AF treatment following an ineffective surgical RF ablation procedure and biological prosthetic MV replacement. The use of bioprosthetic MVs allows for performing safe catheter ablation without subsequent prosthetic dysfunction.

  17. Possible role for cryoballoon ablation of right atrial appendage tachycardia when conventional ablation fails.

    Amasyali, Basri; Kilic, Ayhan


    Focal atrial tachycardia arising from the right atrial appendage usually responds well to radiofrequency ablation; however, successful ablation in this anatomic region can be challenging. Surgical excision of the right atrial appendage has sometimes been necessary to eliminate the tachycardia and prevent or reverse the resultant cardiomyopathy. We report the case of a 48-year-old man who had right atrial appendage tachycardia resistant to multiple attempts at ablation with use of conventional radiofrequency energy guided by means of a 3-dimensional mapping system. The condition led to cardiomyopathy in 3 months. The arrhythmia was successfully ablated with use of a 28-mm cryoballoon catheter that had originally been developed for catheter ablation of paroxysmal atrial fibrillation. To our knowledge, this is the first report of cryoballoon ablation without isolation of the right atrial appendage. It might also be an alternative to epicardial ablation or surgery when refractory atrial tachycardia originates from the right atrial appendage.

  18. Attitudes Towards Catheter Ablation for Atrial Fibrillation

    Vadmann, Henrik; Pedersen, Susanne S; Nielsen, Jens Cosedis;


    BACKGROUND: Catheter ablation for atrial fibrillation (AF) is an important but expensive procedure that is the subject of some debate. Physicians´ attitudes towards catheter ablation may influence promotion and patient acceptance. This is the first study to examine the attitudes of Danish...

  19. Laser systems for ablative fractional resurfacing

    Paasch, Uwe; Haedersdal, Merete


    Ablative fractional resurfacing (AFR) creates microscopic vertical ablated channels that are surrounded by a thin layer of coagulated tissue, constituting the microscopic treatment zones (MTZs). AFR induces epidermal and dermal remodeling, which raises new possibilities for the treatment of a var...

  20. Therapy of HCC-radiofrequency ablation.

    Buscarini, L; Buscarini, E


    Radiofrequency interstitial hyperthermia has been used for percutaneous ablation of hepatocellular carcinoma, under ultrasound guidance in local anesthesia. Conventional needle electrodes require a mean number of 3 sessions to treat tumors of diameter hemotorax in one case; a fluid collection in the site of ablated tumor in one patient treated by combination of transcatheter arterial embolization and radiofrequency application.

  1. Effective temperatures of polymer laser ablation

    Furzikov, Nickolay P.


    Effective temperatures of laser ablation of certain polymers are extracted from experimental dependences of ablation depths on laser fluences. Dependence of these temperatures on laser pulse durations is established. Comparison with the known thermodestruction data shows that the effective temperature corresponds to transient thermodestruction proceeding by the statistically most probable way.

  2. VUV laser ablation of polymers. Photochemical aspect

    Castex, M. C.; Bityurin, N.; Olivero, C.; Muraviov, S.; Bronnikova, N.; Riedel, D.


    A photochemical theory of laser ablation owing to the direct chain scission process is considered in quite general form taking into account the modification of material. The formulas obtained can be used for estimating mechanisms of VUV laser ablation of polymers.

  3. Preventing re-displacement through genuine reintegration in Burundi

    Lucy Hovil


    Full Text Available Displacement is often part of a cyclical process of conflict anddisplacement. Preventing displacement, therefore, is not only aboutpreventing new displacement but about ensuring that people do notget re-displaced.

  4. Modelling toehold-mediated RNA strand displacement

    Šulc, Petr; Romano, Flavio; Doye, Jonathan P K; Louis, Ard A


    We study the thermodynamics and kinetics of an RNA toehold-mediated strand displacement reaction with a recently developed coarse-grained model of RNA. Strand displacement, during which a single strand displaces a different strand previously bound to a complementary substrate strand, is an essential mechanism in active nucleic acid nanotechnology and has also been hypothesized to occur in vivo. We study the rate of displacement reactions as a function of the length of the toehold and temperature and make two experimentally testable predictions: that the displacement is faster if the toehold is placed at the 5' end of the substrate and that the displacement slows down with increasing temperature for longer toeholds.

  5. High Heat Flux Block Ablator-in-Honeycomb Heat Shield Using Ablator/Aerogel-Filled Foam Project

    National Aeronautics and Space Administration — Ultramet and ARA Ablatives Laboratory previously developed and demonstrated advanced foam-reinforced carbon/phenolic ablators that offer substantially increased high...


    Budi Utomo


    Full Text Available Displacement is weight water which is replaced ship hull. The displacement influenced by dimension of inmerchant ship. The displacement musat be small as posible, but the capacity and the speed must be pullfill.Dsplacement can be obtained by formulation or by experiment in hydrodinamika laobatory, the modelingcharacteristic us descube the real Calculation of the ship.The form of the ship must give the resistaise as small as posible. In athe hard the capacity must be full fill ofload

  7. Tumor ablation with irreversible electroporation.

    Bassim Al-Sakere

    Full Text Available We report the first successful use of irreversible electroporation for the minimally invasive treatment of aggressive cutaneous tumors implanted in mice. Irreversible electroporation is a newly developed non-thermal tissue ablation technique in which certain short duration electrical fields are used to permanently permeabilize the cell membrane, presumably through the formation of nanoscale defects in the cell membrane. Mathematical models of the electrical and thermal fields that develop during the application of the pulses were used to design an efficient treatment protocol with minimal heating of the tissue. Tumor regression was confirmed by histological studies which also revealed that it occurred as a direct result of irreversible cell membrane permeabilization. Parametric studies show that the successful outcome of the procedure is related to the applied electric field strength, the total pulse duration as well as the temporal mode of delivery of the pulses. Our best results were obtained using plate electrodes to deliver across the tumor 80 pulses of 100 micros at 0.3 Hz with an electrical field magnitude of 2500 V/cm. These conditions induced complete regression in 12 out of 13 treated tumors, (92%, in the absence of tissue heating. Irreversible electroporation is thus a new effective modality for non-thermal tumor ablation.

  8. Femtosecond ablation of ultrahard materials

    Dumitru, G.; Romano, V.; Weber, H. P.; Sentis, M.; Marine, W.

    Several ultrahard materials and coatings of definite interest for tribological applications were tested with respect to their response when irradiated with fs laser pulses. Results on cemented tungsten carbide and on titanium carbonitride are reported for the first time and compared with outcomes of investigations on diamond and titanium nitride. The experiments were carried out in air, in a regime of 5-8 J/cm2 fluences, using the beam of a commercial Ti:sapphire laser. The changes induced in the surface morphology were analysed with a Nomarski optical microscope, and with SEM and AFM techniques. From the experimental data and from the calculated incident energy density distributions, the damage and ablation threshold values were determined. As expected, the diamond showed the highest threshold, while the cemented tungsten carbide exhibited typical values for metallic surfaces. The ablation rates determined (under the above-mentioned experimental conditions) were in the range 0.1-0.2 μm per pulse for all the materials investigated.

  9. Displacement of Propagating Squeezed Microwave States

    Fedorov, Kirill G.; Zhong, L.; Pogorzalek, S.; Eder, P.; Fischer, M.; Goetz, J.; Xie, E.; Wulschner, F.; Inomata, K.; Yamamoto, T.; Nakamura, Y.; Di Candia, R.; Las Heras, U.; Sanz, M.; Solano, E.; Menzel, E. P.; Deppe, F.; Marx, A.; Gross, R.


    Displacement of propagating quantum states of light is a fundamental operation for quantum communication. It enables fundamental studies on macroscopic quantum coherence and plays an important role in quantum teleportation protocols with continuous variables. In our experiments, we have successfully implemented this operation for propagating squeezed microwave states. We demonstrate that, even for strong displacement amplitudes, there is no degradation of the squeezing level in the reconstructed quantum states. Furthermore, we confirm that path entanglement generated by using displaced squeezed states remains constant over a wide range of the displacement power.

  10. Tracking speckle displacement by double Kalman filtering

    Donghui Li; Li Guo


    @@ A tracking technique using two sequentially-connected Kalman filter for tracking laser speckle displacement is presented. One Kalman filter tracks temporal speckle displacement, while another Kalman filter tracks spatial speckle displacement. The temporal Kalman filter provides a prior for the spatial Kalman filter, and the spatial Kalman filter provides measurements for the temporal Kalman filter. The contribution of a prior to estimations of the spatial Kalman filter is analyzed. An optical analysis system was set up to verify the double-Kalman-filter tracker's ability of tracking laser speckle's constant displacement.

  11. Displacement based multilevel structural optimization

    Striz, Alfred G.


    Multidisciplinary design optimization (MDO) is expected to play a major role in the competitive transportation industries of tomorrow, i.e., in the design of aircraft and spacecraft, of high speed trains, boats, and automobiles. All of these vehicles require maximum performance at minimum weight to keep fuel consumption low and conserve resources. Here, MDO can deliver mathematically based design tools to create systems with optimum performance subject to the constraints of disciplines such as structures, aerodynamics, controls, etc. Although some applications of MDO are beginning to surface, the key to a widespread use of this technology lies in the improvement of its efficiency. This aspect is investigated here for the MDO subset of structural optimization, i.e., for the weight minimization of a given structure under size, strength, and displacement constraints. Specifically, finite element based multilevel optimization of structures (here, statically indeterminate trusses and beams for proof of concept) is performed. In the system level optimization, the design variables are the coefficients of assumed displacement functions, and the load unbalance resulting from the solution of the stiffness equations is minimized. Constraints are placed on the deflection amplitudes and the weight of the structure. In the subsystems level optimizations, the weight of each element is minimized under the action of stress constraints, with the cross sectional dimensions as design variables. This approach is expected to prove very efficient, especially for complex structures, since the design task is broken down into a large number of small and efficiently handled subtasks, each with only a small number of variables. This partitioning will also allow for the use of parallel computing, first, by sending the system and subsystems level computations to two different processors, ultimately, by performing all subsystems level optimizations in a massively parallel manner on separate

  12. Direct investigation of the ablation rate evolution during laser drilling of high-aspect-ratio micro-holes

    Mezzapesa, Francesco P.; Sibillano, Teresa; Columbo, Lorenzo L.; Di Niso, Francesca; Ancona, Antonio; Dabbicco, Maurizio; De Lucia, Francesco; Lugarà, Pietro M.; Scamarcio, Gaetano


    The recent development of ultrafast laser ablation technology in precision micromachining has dramatically increased the demand for reliable and real-time detection systems to characterize the material removal process. In particular, the laser percussion drilling of metals is lacking of non-invasive techniques able to monitor into the depth the spatial- and time-dependent evolution all through the ablation process. To understand the physical interaction between bulk material and high-energy light beam, accurate in-situ measurements of process parameters such as the penetration depth and the removal rate are crucial. We report on direct real time measurements of the ablation front displacement and the removal rate during ultrafast laser percussion drilling of metals by implementing a contactless sensing technique based on optical feedback interferometry. High aspect ratio micro-holes were drilled onto steel plates with different thermal properties (AISI 1095 and AISI 301) and Aluminum samples using 120-ps/110-kHz pulses delivered by a microchip laser fiber amplifier. Percussion drilling experiments have been performed by coaxially aligning the diode laser probe beam with the ablating laser. The displacement of the penetration front was instantaneously measured during the process with a resolution of 0.41 μm by analyzing the sawtooth-like induced modulation of the interferometric signal out of the detector system.

  13. Arizona: In Search of the Displaced Homemaker.

    Woods, Doris

    The model described offers information about displaced homemakers that, while specific to Arizona, can provide a guide to persons in any state responsible for program planning. The report presents results of an Arizona Department of Education study which was conducted to: (1) identify the "displaced homemaker;" (2) define the need for services;…

  14. Seismic displacement of gravity retaining walls

    Kamal Mohamed Hafez Ismail Ibrahim


    Full Text Available Seismic displacement of gravity walls had been studied using conventional static methods for controlled displacement design. In this study plain strain numerical analysis is performed using Plaxis dynamic program where prescribed displacement is applied at the bottom boundary of the soil to simulate the applied seismic load. Constrained absorbent side boundaries are introduced to prevent any wave reflection. The studied soil is chosen dense granular sand and modeled as elasto-plastic material according to Mohr–Column criteria while the gravity wall is assumed elastic. By comparing the resulted seismic wall displacements calculated by numerical analysis for six historical ground motions with that calculated by the pseudo-static method, it is found that numerical seismic displacements are either equal to or greater than corresponding pseudo-static values. Permissible seismic wall displacement calculated by AASHTO can be used for empirical estimation of seismic displacement. It is also found that seismic wall displacement is directly proportional with the positive angle of inclination of the back surface of the wall, soil flexibility and with the earthquake maximum ground acceleration. Seismic wall sliding is dominant and rotation is negligible for rigid walls when the ratio between the wall height and the foundation width is less than 1.4, while for greater ratios the wall becomes more flexible and rotation (rocking increases till the ratio reaches 1.8 where overturning is susceptible to take place. Cumulative seismic wall rotation increases with dynamic time and tends to be constant at the end of earthquake.

  15. Flow cell system for miscible displacement experiments

    Yoo, S.H.; Kirkham, D.


    The use of a continuous graphic recording system for flow-component measurement in miscible displacement experiments is described. This system measures and continuously records radioactive tracer concentrations of effluents of miscible displacement columns. The recordings are needed breakthrough curves. The use of the system obviates fraction collectors.

  16. Etiopathogenesis of abomasal displacement in cattle

    Šamanc Horea


    Full Text Available Abomasal displacement presents topographic gastropathy, where this organ has changed its position, and there is simultaneous dilatation which can vary in intensity. The incidence of this disorder in herds of high-yield dairy cows varies to a great degree (1 to 18 %. Abomasal displacement was established in herds of East-Frisian cows in 1 to 3% animals, and in Holstein cow herds in 5 to 18 % animals. The most frequent abomasal displacement is to the left (88%. There is significant seasonal variation in the incidence of abomasal displacement. About two-thirds of cases of abomasal displacement are diagnosed from October until April. The disorder appears more frequently in cows with repeated lactations. It has been established that it appears after the first calving in 27.8% cases, after the second to fifth calving in 66.7% cases, and after the sixth and seventh calving in 5.5% of the cows. The response of endocrine pancreas B-cells for insulin secretion to hyperglycaemia caused by applying an excess-glucose test is reduced in cows with left abomasal displacement, and there is constant hyperglycaemia in cows with right abomasal displacement. The excess-glucose test indicates a disrupted function of the endocrine pancreas in diseased animals. It has been determined through examinations of Aml genotypes in Holstein cow herds in connection with the appearance of abomasal displacement, that the occurrence of this disorder cannot be attributed to a genetic predisposition.

  17. Analysis of infrared laser tissue ablation

    McKenzie, Gordon P.; Timmerman, Brenda H.; Bryanston-Cross, Peter J.


    The mechanisms involved in infrared laser tissue ablation are studied using a free electron laser (FELIX) in order to clarify whether the increased ablation efficiency reported in literature for certain infrared wavelengths is due to a wavelength effect or to the specific pulse structure of the lasers that are generally used in these studies. Investigations are presented of ablation of vitreous from pigs" eyes using several techniques including protein gel electrophoresis and ablation plume visualization. The ablation effects of three different infrared wavelengths are compared: 3 mm, which is currently in clinical surgical use, and the wavelengths associated with the amide I and amide II bands, i.e. 6.2 mm and 6.45mm, respectively. The results suggest a different ablation mechanism to be in operation for each studied wavelength, thus indicating that the generally reported increased ablation efficiency in the 6-6.5 micron range is due to the wavelength rather than the typical free electron laser pulse structure.

  18. Internal displacement in Colombia: Fifteen distinguishing features.

    Shultz, James M; Ceballos, Ángela Milena Gómez; Espinel, Zelde; Oliveros, Sofia Rios; Fonseca, Maria Fernanda; Florez, Luis Jorge Hernandez


    This commentary aims to delineate the distinguishing features of conflict-induced internal displacement in the nation of Colombia, South America. Even as Colombia is currently implementing a spectrum of legal, social, economic, and health programs for "victims of armed conflict," with particular focus on internally displaced persons (IDPs), the dynamics of forced migration on a mass scale within this country are little known beyond national borders.   The authors of this commentary are embarking on a global mental health research program in Bogota, Colombia to define best practices for reaching the displaced population and implementing sustainable, evidence-based screening and intervention for common mental disorders. Presenting the defining characteristics of internal displacement in Colombia provides the context for our work and, more importantly, conveys the compelling and complex nature of this humanitarian crisis. We attempt to demonstrate Colombia's unique position within the global patterning of internal displacement.

  19. Nonsurgical gingival displacement in restorative dentistry.

    Thomas, Manuel S; Joseph, Robin Mathai; Parolia, Abhishek


    Gingival displacement is critical for obtaining accurate impressions for the fabrication of fixed restorations, especially when the finish line is at or just within the gingival sulcus. Displacement of the gingival tissue is also important when dealing with the restoration of cervical lesions due to their proximity to the periodontal tissue. The methods of gingival tissue displacement can be broadly classified as nonsurgical and surgical techniques, with nonsurgical being the more commonly practiced method. Dentists must alter their armamentarium and gingival displacement techniques to meet specific demands and obtain predictable results. Hence, the purpose of this article is to describe the different means by which nonsurgical gingival displacement can be achieved effectively under a variety of clinical situations.

  20. UV Laser Ablation of Electronically Conductive Polymers


    deionized water. The polymerization solution for polyaniline was prepared by mixing equal volumes of a solution that was 0.25 M in ammonium persulfate with a...rum2,0 vvcsL) TbeUV.layer ablation of thin polypyrrole and polyaniline films coated on an insulating substrate is described. UV laser ablation is used to...11liiii929. 6 1 2:- A ABSTRACT The UV laser ablation of thin polypyrrole and polyaniline films coated on an insulating substrate is described. UV laser

  1. Hydrodynamic modeling of ns-laser ablation

    David Autrique


    Full Text Available Laser ablation is a versatile and widespread technique, applied in an increasing number of medical, industrial and analytical applications. A hydrodynamic multiphase model describing nanosecond-laser ablation (ns-LA is outlined. The model accounts for target heating and mass removal mechanisms as well as plume expansion and plasma formation. A copper target is placed in an ambient environment consisting of helium and irradiated by a nanosecond-laser pulse. The effect of variable laser settings on the ablation process is explored in 1-D numerical simulations.

  2. Diamond Ablators for Inertial Confinement Fusion

    Biener, J; Mirkarimi, P B; Tringe, J W; Baker, S L; Wang, Y M; Kucheyev, S O; Teslich, N E; Wu, K J; Hamza, A V; Wild, C; Woerner, E; Koidl, P; Bruehne, K; Fecht, H


    Diamond has a unique combination of physical properties for the inertial confinement fusion ablator application, such as appropriate optical properties, high atomic density, high yield strength, and high thermal conductivity. Here, we present a feasible concept to fabricate diamond ablator shells. The fabrication of diamond capsules is a multi-step process, which involves diamond chemical vapor deposition on silicon mandrels followed by polishing, microfabrication of holes, and removing of the silicon mandrel by an etch process. We also discuss the pros and cons of coarse-grained optical quality and nanocrystalline chemical vapor deposition diamond films for the ablator application.

  3. Ablation response testing of aerospace power supplies

    Lutz, S. A.; Chan, C. C.


    An experimental program was performed to assess the aerothermal ablation response of aerospace power supplies. Full-scale General Purpose Heat Source (GPHS) test articles, Graphite Impact Shell (GIS) test articles, and Lightweight Radioisotope Heater Unit (LWRHU) test articles were all tested without nuclear fuel in simulated reentry environments at the NASA Ames Research Center. Stagnation heating, stagnation pressure, stagnation surface temperature, stagnation surface recession profile, and weight loss measurements were obtained for diffusion-limited and sublimation ablation conditions. The recession profile and weight loss measurements showed an effect of surface features on the stagnation face. The surface features altered the local heating which in turn affected the local ablation.

  4. Use of a circular mapping and ablation catheter for ablation of atypical right ventricular outflow tract arrhythmia.

    Katritsis, Demosthenes G; Giazitzoglou, Eleftherios; Paxinos, George


    A new technique for ablation of persistent ectopic activity with atypical electrocardiographic characteristics at the vicinity of the right ventricular outflow tract is described. A new circular mapping and ablation catheter initially designed for pulmonary vein ablation was used. Abolition of ectopic activity was achieved with minimal fluoroscopy and ablation times.

  5. Cryoballoon or Radiofrequency Ablation for Paroxysmal Atrial Fibrillation.

    Chun, KR; Bestehorn, K; Pocock, SJ; FIRE AND ICE Investigators; , COLLABORATORS; Kuck, KH; Metzner, A; Ouyang, F; Chun, J; Fürnkranz, A; Elvan, A.; Arentz, T.; Kühne, M.; Sticherling, C; Gellér, L


    BACKGROUND: Current guidelines recommend pulmonary-vein isolation by means of catheter ablation as treatment for drug-refractory paroxysmal atrial fibrillation. Radiofrequency ablation is the most common method, and cryoballoon ablation is the second most frequently used technology. METHODS: We conducted a multicenter, randomized trial to determine whether cryoballoon ablation was noninferior to radiofrequency ablation in symptomatic patients with drug-refractory paroxysmal atrial fibrillatio...

  6. Nanosecond laser ablation of silver nanoparticle film

    Chung, Jaewon; Han, Sewoon; Lee, Daeho; Ahn, Sanghoon; Grigoropoulos, Costas P.; Moon, Jooho; Ko, Seung H.


    Nanosecond laser ablation of polyvinylpyrrolidone (PVP) protected silver nanoparticle (20 nm diameter) film is studied using a frequency doubled Nd:YAG nanosecond laser (532 nm wavelength, 6 ns full width half maximum pulse width). In the sintered silver nanoparticle film, absorbed light energy conducts well through the sintered porous structure, resulting in ablation craters of a porous dome shape or crown shape depending on the irradiation fluence due to the sudden vaporization of the PVP. In the unsintered silver nanoparticle film, the ablation crater with a clean edge profile is formed and many coalesced nanoparticles of 50 to 100 nm in size are observed inside the ablation crater. These results and an order of magnitude analysis indicate that the absorbed thermal energy is confined within the nanoparticles, causing melting of nanoparticles and their coalescence to larger agglomerates, which are removed following melting and subsequent partial vaporization.

  7. Laser ablation in analytical chemistry - A review

    Russo, Richard E.; Mao, Xianglei; Liu, Haichen; Gonzalez, Jhanis; Mao, Samuel S.


    Laser ablation is becoming a dominant technology for direct solid sampling in analytical chemistry. Laser ablation refers to the process in which an intense burst of energy delivered by a short laser pulse is used to sample (remove a portion of) a material. The advantages of laser ablation chemical analysis include direct characterization of solids, no chemical procedures for dissolution, reduced risk of contamination or sample loss, analysis of very small samples not separable for solution analysis, and determination of spatial distributions of elemental composition. This review describes recent research to understand and utilize laser ablation for direct solid sampling, with emphasis on sample introduction to an inductively coupled plasma (ICP). Current research related to contemporary experimental systems, calibration and optimization, and fractionation is discussed, with a summary of applications in several areas.

  8. Physical processes of laser tissue ablation

    Furzikov, Nickolay P.


    The revised ablation model applicable to homogeneous tissues is presented. It is based on the thermal mechanism and involves the instability of the laserinduced evaporation (thermodestruction) front the growth of the surface ripple structure the interference of the laser wave and of the surface wave arising by diffraction on the ripples Beer''s law violation the pulsed thermodestruction of the organic structural component the tissue water boiling and gas dynamic expansion of the resulting products into the surrounding medium which is followed by the shock wave formation. The UV and IR ablation schemes were implemented and compared to the corneal ablation experiments. The initial ablation pressure and temperature are given restored from the timeofflight measurements of the supersonic expansion of the product. 1.

  9. Laser ablation of a polysilane material

    Hansen, S. G.; Robitaille, T. E.


    The laser ablation properties of a (50%)-isopropyl methyl-(50%)-n-propyl methyl silane copolymer are examined. Both 193- and 248-nm-pulsed excimer laser radiation cleanly and completely remove this material in vacuum above certain energy thresholds (30 and 50 mJ/cm2, respectively). Under these conditions the ablation properties are quite similar to those reported for typical organic polymers. Below threshold, ablation is less efficient and becomes increasingly inefficient as irradiation continues due to spectral bleaching. In the presence of air, material removal is incomplete even for high-energy densities and long exposures. The ablation rate is shown to be independent of substrate material both above and below threshold.

  10. Ablative Ceramic Foam Based TPS Project

    National Aeronautics and Space Administration — A novel composite material ablative TPS for planetary vehicles that can survive a dual heating exposure is proposed. NextGen's TPS concept is a bi-layer functional...

  11. Principles of the radiative ablation modeling

    Saillard, Yves; Arnault, Philippe; Silvert, Virginie


    Indirectly driven inertial confinement fusion (ICF) rests on the setting up of a radiation temperature within a laser cavity and on the optimization of the capsule implosion ablated by this radiation. In both circumstances, the ablation of an optically thick medium is at work. The nonlinear radiation conduction equations that describe this phenomenon admit different kinds of solutions called generically Marshak waves. In this paper, a completely analytic model is proposed to describe the ablation in the subsonic regime relevant to ICF experiments. This model approximates the flow by a deflagrationlike structure where Hugoniot relations are used in the stationary part from the ablation front up to the isothermal sonic Chapman-Jouguet point and where the unstationary expansion from the sonic point up to the external boundary is assumed quasi-isothermal. It uses power law matter properties. It can also accommodate arbitrary boundary conditions provided the ablation wave stays very subsonic and the surface temperature does not vary too quickly. These requirements are often met in realistic situations. Interestingly, the ablated mass rate, the ablation pressure, and the absorbed radiative energy depend on the time history of the surface temperature, not only on the instantaneous temperature values. The results compare very well with self-similar solutions and with numerical simulations obtained by hydrodynamic code. This analytic model gives insight into the physical processes involved in the ablation and is helpful for optimization and sensitivity studies in many situations of interest: radiation temperature within a laser cavity, acceleration of finite size medium, and ICF capsule implosion, for instance.


    Ch. Madh


    Full Text Available Adenoma sebaceum, pathognomonic of tuberous sclerosis, are tiny angiofibromas which commonly occur over central part of face. Recurrence after treatment is common and hence a need for inexpensive, safe and efficient treatment is required. Radiofrequency ablation is a safe and an economical procedure and has been known to cause less scarring with good aesthetic results compared to other ablative methods such as electrocautery.

  13. Variable displacement alpha-type Stirling engine

    Homutescu, V. M.; Bălănescu, D. T.; Panaite, C. E.; Atanasiu, M. V.


    The basic design and construction of an alpha-type Stirling engine with on load variable displacement is presented. The variable displacement is obtained through a planar quadrilateral linkage with one on load movable ground link. The physico-mathematical model used for analyzing the variable displacement alpha-type Stirling engine behavior is an isothermal model that takes into account the real movement of the pistons. Performances and power adjustment capabilities of such alpha-type Stirling engine are calculated and analyzed. An exemplification through the use of the numerical simulation was performed in this regard.

  14. Epitaxial growth by monolayer restricted galvanic displacement

    Vasilić Rastko


    Full Text Available The development of a new method for epitaxial growth of metals in solution by galvanic displacement of layers pre-deposited by underpotential deposition (UPD was discussed and experimentally illustrated throughout the lecture. Cyclic voltammetry (CV and scanning tunneling microscopy (STM are employed to carry out and monitor a “quasi-perfect”, two-dimensional growth of Ag on Au(111, Cu on Ag(111, and Cu on Au(111 by repetitive galvanic displacement of underpotentially deposited monolayers. A comparative study emphasizes the displacement stoichiometry as an efficient tool for thickness control during the deposition process and as a key parameter that affects the deposit morphology. The excellent quality of layers deposited by monolayer-restricted galvanic displacement is manifested by a steady UPD voltammetry and ascertained by a flat and uniform surface morphology maintained during the entire growth process.

  15. Assisting the return of displaced Dinka Bor

    Paul Murphy


    Full Text Available The issues involved in supporting the return of internally displaced Dinka Bor communities highlight the complex, and often ignored, challenges of addressing the consequencesof South-South conflict.

  16. Displacement and deformation analysis for uplift piles


    On the assumptions that the shear resistance increases linearly with increasing shear displacement between the uplift pile and surrounding soil,that the axis force is distributed as parabola along the pile length,that elastic distortion occurs when the pile is loaded,that the displacement of pile is in accord with that of the soil,and that the uplift pile failure is regarded as the soil failure,arational calculation method was proposed for calculating the deformation,ultimate displacement and shear resistance of piles.The distributions of frictional resistance and the shear displacement along the pile length were obtained with the method.The comparisons were made between the measurement results and the present results.The present theoretical results agree well with the measurement results,with the average difference being less than 12% before failure.The comparisons show that the proposed method is reasonable for uplift design and engineering construction of piles.

  17. Variance and covariance of accumulated displacement estimates.

    Bayer, Matthew; Hall, Timothy J


    Tracking large deformations in tissue using ultrasound can enable the reconstruction of nonlinear elastic parameters, but poses a challenge to displacement estimation algorithms. Such large deformations have to be broken up into steps, each of which contributes an estimation error to the final accumulated displacement map. The work reported here measured the error variance for single-step and accumulated displacement estimates using one-dimensional numerical simulations of ultrasound echo signals, subjected to tissue strain and electronic noise. The covariance between accumulation steps was also computed. These simulations show that errors due to electronic noise are negatively correlated between steps, and therefore accumulate slowly, whereas errors due to tissue deformation are positively correlated and accumulate quickly. For reasonably low electronic noise levels, the error variance in the accumulated displacement estimates is remarkably constant as a function of step size, but increases with the length of the tracking kernel.

  18. Navigated Percutaneous Lung Ablation under High-Frequency Jet Ventilation of a Metastasis from a Wilms’ Tumour: A Paediatric Case Report

    Jacob Freedman


    Full Text Available This is a case report of microwave energy being used to ablate an inoperable metastasis of a Wilms’ tumour in a 6-year-old boy using state-of-the-art navigated computed tomography targeting and high-frequency jet ventilation to reduce organ displacement and the potential risk of procedure-related pneumothorax. After the ablation, the young boy had high-dose chemotherapy followed by an autologous stem cell transplantation with rapid reduction of three recurrent right-sided lung metastases.

  19. 2014 and beyond: implications for displacement

    Aidan O’Leary


    Full Text Available 2014 marks a watershed for Afghanistan, with the withdrawal of the International Security Assistance Force after twelve years, and the very real risks this withdrawal poses to the capacity of the Afghan state to meet the many internal and external challenges faced by the country. These challenges have significant implications for displaced and returning Afghans and for the potential for displacement in the future.

  20. Monolithically integrated interferometer for optical displacement measurement

    Hofstetter, Daniel; Zappe, Hans P.


    We discuss the fabrication of a monolithically integrated optical displacement sensors using III-V semiconductor technology. The device is configured as a Michelson interferometer and consists of a distributed Bragg reflector laser, a photodetector and waveguides forming a directional coupler. Using this interferometer, displacements in the 100 nm range could be measured at distances of up to 45 cm. We present fabrication, device results and characterization of the completed interferometer, problems, limitations and future applications will also be discussed.

  1. Percutaneous Microwave Ablation of Renal Angiomyolipomas

    Cristescu, Mircea, E-mail: [University of Wisconsin, Department of Radiology (United States); Abel, E. Jason, E-mail: [University of Wisconsin, Department of Urology (United States); Wells, Shane, E-mail:; Ziemlewicz, Timothy J., E-mail: [University of Wisconsin, Department of Radiology (United States); Hedican, Sean P., E-mail: [University of Wisconsin, Department of Urology (United States); Lubner, Megan G., E-mail:; Hinshaw, J. Louis, E-mail:; Brace, Christopher L., E-mail:; Lee, Fred T., E-mail: [University of Wisconsin, Department of Radiology (United States)


    PurposeTo evaluate the safety and efficacy of US-guided percutaneous microwave (MW) ablation in the treatment of renal angiomyolipoma (AML).Materials and MethodsFrom January 2011 to April 2014, seven patients (5 females and 2 males; mean age 51.4) with 11 renal AMLs (9 sporadic type and 2 tuberous sclerosis associated) with a mean size of 3.4 ± 0.7 cm (range 2.4–4.9 cm) were treated with high-powered, gas-cooled percutaneous MW ablation under US guidance. Tumoral diameter, volume, and CT/MR enhancement were measured on pre-treatment, immediate post-ablation, and delayed post-ablation imaging. Clinical symptoms and creatinine were assessed on follow-up visits.ResultsAll ablations were technically successful and no major complications were encountered. Mean ablation parameters were ablation power of 65 W (range 60–70 W), using 456 mL of hydrodissection fluid per patient, over 4.7 min (range 3–8 min). Immediate post-ablation imaging demonstrated mean tumor diameter and volume decreases of 1.8 % (3.4–3.3 cm) and 1.7 % (27.5–26.3 cm{sup 3}), respectively. Delayed imaging follow-up obtained at a mean interval of 23.1 months (median 17.6; range 9–47) demonstrated mean tumor diameter and volume decreases of 29 % (3.4–2.4 cm) and 47 % (27.5–12.1 cm{sup 3}), respectively. Tumoral enhancement decreased on immediate post-procedure and delayed imaging by CT/MR parameters, indicating decreased tumor vascularity. No patients required additional intervention and no patients experienced spontaneous bleeding post-ablation.ConclusionOur early experience with high-powered, gas-cooled percutaneous MW ablation demonstrates it to be a safe and effective modality to devascularize and decrease the size of renal AMLs.

  2. Dust ablation in Pluto's atmosphere

    Horanyi, Mihaly; Poppe, Andrew; Sternovsky, Zoltan


    Based on measurements by dust detectors onboard the Pioneer 10/11 and New Horizons spacecraft the total production rate of dust particles born in the Edgeworth Kuiper Belt (EKB) has been be estimated to be on the order of 5 ṡ 103 kg/s in the approximate size range of 1 - 10 μm. Dust particles are produced by collisions between EKB objects and their bombardment by both interplanetary and interstellar dust particles. Dust particles of EKB origin, in general, migrate towards the Sun due to Poynting-Robertson drag but their distributions are further sculpted by mean-motion resonances as they first approach the orbit of Neptune and later the other planets, as well as mutual collisions. Subsequently, Jupiter will eject the vast majority of them before they reach the inner solar system. The expected mass influx into Pluto atmosphere is on the order of 200 kg/day, and the arrival speed of the incoming particles is on the order of 3 - 4 km/s. We have followed the ablation history as function of speed and size of dust particles in Pluto's atmosphere, and found that volatile rich particles can fully sublimate due to drag heating and deposit their mass in narrow layers. This deposition might promote the formation of the haze layers observed by the New Horizons spacecraft. This talk will explore the constraints on the composition of the dust particles by comparing the altitude of the deposition layers to the observed haze layers.

  3. Fractional ablative erbium YAG laser

    Taudorf, Elisabeth H; Haak, Christina S; Erlendsson, Andrés M


    BACKGROUND AND OBJECTIVES: Treatment of a variety of skin disorders with ablative fractional lasers (AFXL) is driving the development of portable AFXLs. This study measures micropore dimensions produced by a small 2,940 nm AFXL using a variety of stacked pulses, and determines a model correlating...... laser parameters with tissue effects. MATERIALS AND METHODS: Ex vivo pig skin was exposed to a miniaturized 2,940 nm AFXL, spot size 225 µm, density 5%, power levels 1.15-2.22 W, pulse durations 50-225 microseconds, pulse repetition rates 100-500 Hz, and 2, 20, or 50 stacked pulses, resulting in pulse...... 190 to 347 µm. CONCLUSIONS: Pulse stacking with a small, low power 2,940 nm AFXL created reproducible shallow to deep micropores, and influenced micropore configuration. Mathematical modeling established relations between laser settings and micropore dimensions, which assists in choosing laser...

  4. Femtosecond laser ablation of silicon in air and vacuum

    Zehua Wu; Nan Zhang; Mingwei Wang; Xiaonong Zhu


    Femtosecond (fs) pulse laser ablation of silicon targets in air and in vacuum is investigated using a time-resolved shadowgraphic method. The observed dynamic process of the fs laser ablation of silicon in air is significantly different from that in vacuum. Similar to the ablation of metallic targets, while the shock wave front and a series of nearly concentric and semicircular stripes, as well as the contact front, are clearly identifiable in the process of ablation under 1 x 105 Pa, these phenomena are no longer observed when the ablation takes place in vacuum. Although the ambient air around the target strongly affects the evolution of the ablation plume, the three rounds of material ejection clearly observed in the shadowgraphs of fs laser ablation in standard air can also be distinguished in the process of ablation in vacuum. It is proven that the three rounds of material ejection are caused by different ablation mechanisms.%@@ Femtosecond(fs)pulse laser ablation of silicon targets in air and in vacuum is investigated using a timeresolved shadowgraphic method.The observed dynamic process of the fs laser ablation of silicon in air is significantly different from that in vacuum.Similar to the ablation of metallic targets,while the shock wave front and a series of nearly concentric and semicircular stripes,as well as the contact front,are clearly identifiable in the process of ablation under 1 x 105 Pa,these phenomena are no longer observed when the ablation takes place in vacuum.Although the ambient air around the target strongly affects the evolution of the ablation plume,the three rounds of material ejection clearly observed in the shadowgraphs of fs laser ablation in standard air can also be distinguished in the process of ablation in vacuum.It is proven that the three rounds of material ejection are caused by different ablation mechanisms.

  5. Ablation enhancement of silicon by ultrashort double-pulse laser ablation

    Zhao, Xin; Shin, Yung C. [Center for Laser-Based Manufacturing, School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)


    In this study, the ultrashort double-pulse ablation of silicon is investigated. An atomistic simulation model is developed to analyze the underlying physics. It is revealed that the double-pulse ablation could significantly increase the ablation rate of silicon, compared with the single pulse ablation with the same total pulse energy, which is totally different from the case of metals. In the long pulse delay range (over 1 ps), the enhancement is caused by the metallic transition of melted silicon with the corresponding absorption efficiency. At ultrashort pulse delay (below 1 ps), the enhancement is due to the electron excitation by the first pulse. The enhancement only occurs at low and moderate laser fluence. The ablation is suppressed at high fluence due to the strong plasma shielding effect.

  6. Attempts to prevent displacement in the occupied Palestinian territories

    Karim Khalil


    Prevention has become a strategy increasingly adopted by the humanitarian community in addressing forced displacement in the occupied Palestinian territories, as well as responding to immediate emergency needs for families displaced or at risk of displacement.

  7. Photoacoustic characterization of radiofrequency ablation lesions

    Bouchard, Richard; Dana, Nicholas; Di Biase, Luigi; Natale, Andrea; Emelianov, Stanislav


    Radiofrequency ablation (RFA) procedures are used to destroy abnormal electrical pathways in the heart that can cause cardiac arrhythmias. Current methods relying on fluoroscopy, echocardiography and electrical conduction mapping are unable to accurately assess ablation lesion size. In an effort to better visualize RFA lesions, photoacoustic (PA) and ultrasonic (US) imaging were utilized to obtain co-registered images of ablated porcine cardiac tissue. The left ventricular free wall of fresh (i.e., never frozen) porcine hearts was harvested within 24 hours of the animals' sacrifice. A THERMOCOOLR Ablation System (Biosense Webster, Inc.) operating at 40 W for 30-60 s was used to induce lesions through the endocardial and epicardial walls of the cardiac samples. Following lesion creation, the ablated tissue samples were placed in 25 °C saline to allow for multi-wavelength PA imaging. Samples were imaged with a VevoR 2100 ultrasound system (VisualSonics, Inc.) using a modified 20-MHz array that could provide laser irradiation to the sample from a pulsed tunable laser (Newport Corp.) to allow for co-registered photoacoustic-ultrasound (PAUS) imaging. PA imaging was conducted from 750-1064 nm, with a surface fluence of approximately 15 mJ/cm2 maintained during imaging. In this preliminary study with PA imaging, the ablated region could be well visualized on the surface of the sample, with contrasts of 6-10 dB achieved at 750 nm. Although imaging penetration depth is a concern, PA imaging shows promise in being able to reliably visualize RF ablation lesions.

  8. Left Atrial Ablation for Atrial Fibrillation

    Sternik, Leonid; Schaff, Hartzel V.; Luria, David; Glikson, Michael; Kogan, Alexander; Malachy, Ateret; First, Maya; Raanani, Ehud


    The maze procedure is the gold standard for the ablation of atrial fibrillation, and the “box lesion” around the pulmonary veins is the most important part of this procedure. We have created this lesion with a bipolar radiofrequency ablator, abandoning the usual use of this device (to achieve bilateral epicardial isolation of the pulmonary veins). From March 2004 through the end of May 2010, we performed surgical ablation of atrial fibrillation in 240 patients. Of this number, 205 underwent operation by a hybrid maze technique and the remaining 35 (our study cohort) underwent the creation of a box lesion around the pulmonary veins by means of a bipolar radiofrequency device. Ablation lines were created by connecting the left atriotomy to the amputated left atrial appendage, with 2 ablation lines made with a bipolar radiofrequency device above and below the pulmonary veins. Lesions were made along the transverse and oblique sinuses by epicardial and endocardial application of a bipolar device. The left atrial isthmus was ablated by bipolar radiofrequency and cryoprobe. No complications were associated with the box lesion: 90% and 89% of patients were in sinus rhythm at 3 and 6 months of follow-up, respectively. By creating a box lesion around the pulmonary veins, we expect to improve transmurality by means of epicardial and endocardial ablation of 1 rather than 2 layers of atrial wall, as in epicardial pulmonary vein isolation. Isolation of the entire posterior wall of the left atrium is better electrophysiologically and renders dissection around the pulmonary veins unnecessary. PMID:21494518

  9. Mechanism of Spatiotemporal Distribution of Laser Ablated Materials

    XU Rong-Qing; CUI Yi-Ping; LU Jian; NI Xiao-Wu


    Interaction between subsequent laser and ablated materials in laser processing changes the laser spatiotemporal distribution and has influences on the efficiency and quality of laser processing. The theoretical and experimental researches on transportation behayiour of ablated materials are provided. It is shown that the velocity distribution of ablated materials is determined by ablation mechanism. The transportation behaviour of ablated materials is controlled by diffusion mechanism and light field force during laser pulse duration while it is only determined by diffusion mechanism when the laser pulse terminates. In addition, the spatiotemporal distribution of ablated materials is presented.

  10. Laser ablation of hepatocellular carcinoma-A review


    A wide range of local thermal ablative therapies have been developed in the treatment of non resectable hepatocellular carcinoma (HCC) in the last decade. Laser ablation (LA) and radiofrequency ablation (RFA) are the two most widely used of these. This article provides an up to date overview of the role of laser ablation in the local treatment of HCC. General principles, technique, image guidance and patient selection are discussed. A review of published data on treatment efficacy, long term outcome and complication rates of laser ablation is included and comparison with RFA made. The role of laser ablation in combination with transcatheter arterial chemoembolisation is also discussed.

  11. Three-dimensional electrode displacement elastography using the Siemens C7F2 fourSight four-dimensional ultrasound transducer.

    Bharat, Shyam; Fisher, Ted G; Varghese, Tomy; Hall, Timothy J; Jiang, Jingfeng; Madsen, Ernest L; Zagzebski, James A; Lee, Fred T


    Because ablation therapy alters the elastic modulus of tissues, emerging strain imaging methods may enable clinicians for the first time to have readily available, cost-effective, real-time guidance to identify the location and boundaries of thermal lesions. Electrode displacement elastography is a method of strain imaging tailored specifically to ultrasound-guided electrode-based ablative therapies (e.g., radio-frequency ablation). Here tissue deformation is achieved by applying minute perturbations to the unconstrained end of the treatment electrode, resulting in localized motion around the end of the electrode embedded in tissue. In this article, we present a method for three-dimensional (3D) elastographic reconstruction from volumetric data acquired using the C7F2 fourSight four-dimensional ultrasound transducer, provided by Siemens Medical Solutions USA, Inc. (Issaquah, WA, USA). Lesion reconstruction is demonstrated for a spherical inclusion centered in a tissue-mimicking phantom, which simulates a thermal lesion embedded in a normal tissue background. Elastographic reconstruction is also performed for a thermal lesion created in vitro in canine liver using radio-frequency ablation. Postprocessing is done on the acquired raw radio-frequency data to form surface-rendered 3D elastograms of the inclusion. Elastographic volume estimates of the inclusion compare reasonably well with the actual known inclusion volume, with 3D electrode displacement elastography slightly underestimating the true inclusion volume.

  12. Measuring fast stochastic displacements of bio-membranes with dynamic optical displacement spectroscopy

    Monzel, C; Schmidt, D; Kleusch, C; Kirchenbüchler, D; Seifert, U; Smith, A-S; Sengupta, K; Merkel, R


    Stochastic displacements or fluctuations of biological membranes are increasingly recognized as an important aspect of many physiological processes, but hitherto their precise quantification in living...

  13. Imaging in percutaneous ablation for atrial fibrillation

    Maksimovic, Ruzica [Erasmus Medical Center, Department of Radiology, GD Rotterdam (Netherlands); Institute for Cardiovascular Diseases of the University Medical Center, Belgrade (Czechoslovakia); Dill, Thorsten [Kerckhoff-Heart Center, Department of Cardiology, Bad Nauheim (Germany); Ristic, Arsen D.; Seferovic, Petar M. [Institute for Cardiovascular Diseases of the University Medical Center, Belgrade (Czechoslovakia)


    Percutaneous ablation for electrical disconnection of the arrhythmogenic foci using various forms of energy has become a well-established technique for treating atrial fibrillation (AF). Success rate in preventing recurrence of AF episodes is high although associated with a significant incidence of pulmonary vein (PV) stenosis and other rare complications. Clinical workup of AF patients includes imaging before and after ablative treatment using different noninvasive and invasive techniques such as conventional angiography, transoesophageal and intracardiac echocardiography, computed tomography (CT) and magnetic resonance imaging (MRI), which offer different information with variable diagnostic accuracy. Evaluation before percutaneous ablation involves assessment of PVs (PV pattern, branching pattern, orientation and ostial size) to facilitate position and size of catheters and reduce procedure time as well as examining the left atrium (presence of thrombi, dimensions and volumes). Imaging after the percutaneous ablation is important for assessment of overall success of the procedure and revealing potential complications. Therefore, imaging methods enable depiction of PVs and the anatomy of surrounding structures essential for preprocedural management and early detection of PV stenosis and other ablation-related procedures, as well as long-term follow-up of these patients. (orig.)

  14. Percutaneous tumor ablation in medical radiology

    Vogl, T.J.; Mack, M.G. [University Hospital Frankfurt Univ. (Germany). Inst. for Diagnostic and Interventional Radiology; Helmberger, T.K. [Klinikum Bogenhausen, Academic Teaching Hospital of the Technical Univ. Munich (Germany). Dept. for Diagnostic and Interventional Radiology and Nuclear Medicine; Reiser, M.F. (eds.) [University Hospitals - Grosshadern and Innenstadt Munich Univ. (Germany). Dept. of Clinical Radiology


    Thermal ablation has become an integral part of oncology, especially in the field of interventional oncology. This very comprehensive book encompasses the different technologies employed in thermal ablation, its indications and the results achieved in various clinical conditions. The first part of the book clearly explains the basics of thermal ablative techniques such as laser-induced thermotherapy, radiofrequency ablation, microwave ablation, cryotherapy, and localized tumor therapy. The latest developments in the application of minimally invasive therapies in localized neoplastic disease are demonstrated. In the main part of the book, techniques of guiding the applicators to the target structures by use of different imaging tools such as ultrasound, computed tomography and magnetic resonance imaging are discussed. The results are presented for a variety of clinical indications, including liver and lung tumors and metastases and some rather rare conditions involving the kidney, the head and neck, the prostate, and soft tissue structures. A large number of acknowledged experts have contributed to the book, which benefits from a lucid structure and excellent images. (orig.)

  15. Fundamental studies of pulsed laser ablation

    Claeyssens, F


    dopant) have resulted in a coherent view of the resulting plume, which exhibits a multi-component structure correlated with different regimes of ablation, which are attributed to ejection from ZnO and ablation from a Zn melt. OES measurements show that the emitting Zn component within the plume accelerates during expansion in vacuum - an observation attributable to the presence of hot, fast electrons in the plume. The same acceleration behaviour is observed in the case of Al atomic emissions resulting from ablation of an Al target in vacuum. Deposition conditions, substrate temperature and background gas pressure were all varied in a quest for optimally aligned, high quality ZnO thin films. Initial ab initio calculations were performed also, to aid in understanding the stability of these c-axis aligned films. The pulsed ultraviolet (lambda = 193, 248 nm) laser ablation of graphite, polycrystalline diamond and ZnO targets has been investigated. Characteristics of the resulting plumes of ablated material have b...

  16. Surface depressions (Lacunas on Bering Glacier, Alaska: a product of downwasting through differential ablation

    P. J. Fleisher


    Full Text Available Bering Glacier lacunas are steep-sided, flat-floored hollows ranging in size from 40 to 60 m wide, 80 to 120 m long, and 35 to 50 m in deep. They are confined within a band of clean ice (1.5 km wide, 5 km long paralleling the eastern margin of the Bering piedmont lobe. The 1993–1995 surge displaced the lacuna band several kilometers onto the foreland. Specifically significant is the formation of a new band of lacunas 5–6 years later in the same location occupied by the displaced band prior to the surge. Conditions essential to lacuna formation were initiated during the surge as overriding ice was thrust into position across the trend of a subglacial trough, leading to stagnation of ice within the trough. Stagnation combined with saturation at depth altered ice texture and density. Exposure of this ice through normal ablation led to areas of differential ablation and the formation of lacunas.

  17. Atomic displacements in bcc dilute alloys

    Hitesh Sharma; S Prakash


    We present here a systematic investigation of the atomic displacements in bcc transition metal (TM) dilute alloys. We have calculated the atomic displacements in bcc (V, Cr, Fe, Nb, Mo, Ta and W) transition metals (TMs) due to 3d, 4d and 5d TMs at the substitutional site using the Kanzaki lattice static method. Wills and Harrison interatomic potential is used to calculate the atomic force constants, the dynamical matrix and the impurity-induced forces. We have thoroughly investigated the atomic displacements using impurities from 3d, 4d and 5d series in the same host metal and the same impurity in different hosts. We have observed a systematic pattern in the atomic displacements for Cr-, Fe-, Nb-, Mo-, Ta- and W-based dilute alloys. The atomic displacements are found to increase with increase in the number of d electrons for all alloys considered except for V dilute alloys. The 3d impurities are found to be more easily dissolved in the 3d host metals than 4d or 5d TMs whereas 4d and 5d impurities show more solubility in 4d and 5d TMs. In general, the relaxation energy calculation suggests that impurities may be easily solvable in 5d TM hosts when compared to 3d or 4d TMs.

  18. Quantification of the vocal folds’ dynamic displacements

    del Socorro Hernández-Montes, María; Muñoz, Silvino; De La Torre, Manuel; Flores, Mauricio; Pérez, Carlos; Mendoza-Santoyo, Fernando


    Fast dynamic data acquisition techniques are required to investigate the motional behavior of the vocal folds (VFs) when they are subjected to a steady air-flow through the trachea. High-speed digital holographic interferometry (DHI) is a non-invasive full-field-of-view technique that has proved its usefulness to study rapid and non-repetitive object movements. Hence it is an ideal technique used here to measure VF displacements and vibration patterns at 2000 fps. Analyses from a set of 200 displacement images showed that VFs’ vibration cycles are established along their width (y) and length (x). Furthermore, the maximum deformation for the right and left VFs’ area may be quantified from these images, which in itself represents an important result in the characterization of this structure. At a controlled air pressure, VF displacements fall within the range ~100-1740 nm, with a calculated precision and accuracy that yields a variation coefficient of 1.91%. High-speed acquisition of full-field images of VFs and their displacement quantification are on their own significant data in the study of their functional and physiological behavior since voice quality and production depend on how they vibrate, i.e. their displacement amplitude and frequency. Additionally, the use of high speed DHI avoids prolonged examinations and represents a significant scientific and technological alternative contribution in advancing the knowledge and working mechanisms of these tissues.

  19. Fingering phenomena during grain-grain displacement

    Mello, Nathália M. P.; Paiva, Humberto A.; Combe, G.; Atman, A. P. F.


    Spontaneous formation of fingered patterns during the displacement of dense granular assemblies was experimentally reported few years ago, in a radial Hele-Shaw cell. Here, by means of discrete element simulations, we have recovered the experimental findings and extended the original study to explore the control parameters space. In particular, using assemblies of grains with different geometries (monodisperse, bidisperse, or polydisperse), we measured the macroscopic stress tensor in the samples in order to confirm some conjectures proposed in analogy with Saffman-Taylor viscous fingering phenomena for immiscible fluids. Considering an axial setup which allows to control the discharge of grains and to follow the trajectory and the pressure gradient along the displacing interface, we have applied the Darcy law for laminar flow in fluids in order to measure an "effective viscosity" for each assembly combination, in an attempt to mimic variation of the viscosity ratio between the injected/displaced fluids in the Saffman-Taylor experiment. The results corroborate the analogy with the viscous fluids displacement, with the bidisperse assembly corresponding to the less viscous geometry. But, differently to fluid case, granular fingers only develop for a specific combination of displaced/injected geometries, and we have demonstrated that it is always related with the formation of a force chain network along the finger direction.

  20. Alcohol septal ablation in patients with hypertrophic obstructive cardiomyopathy

    Jensen, Morten K; Prinz, Christian; Horstkotte, Dieter;


    The infarction induced by alcohol septal ablation (ASA) may predispose to arrhythmia and sudden cardiac death (SCD).......The infarction induced by alcohol septal ablation (ASA) may predispose to arrhythmia and sudden cardiac death (SCD)....

  1. Interactive Volumetry Of Liver Ablation Zones

    Egger, Jan; Brandmaier, Philipp; Seider, Daniel; Gawlitza, Matthias; Strocka, Steffen; Voglreiter, Philip; Dokter, Mark; Hofmann, Michael; Kainz, Bernhard; Hann, Alexander; Chen, Xiaojun; Alhonnoro, Tuomas; Pollari, Mika; Schmalstieg, Dieter; Moche, Michael


    Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique that destroys cancer cells by heat. The heat results from focusing energy in the radiofrequency spectrum through a needle. Amongst others, this can enable the treatment of patients who are not eligible for an open surgery. However, the possibility of recurrent liver cancer due to incomplete ablation of the tumor makes post-interventional monitoring via regular follow-up scans mandatory. These scans have to be carefully inspected for any conspicuousness. Within this study, the RF ablation zones from twelve post-interventional CT acquisitions have been segmented semi-automatically to support the visual inspection. An interactive, graph-based contouring approach, which prefers spherically shaped regions, has been applied. For the quantitative and qualitative analysis of the algorithm's results, manual slice-by-slice segmentations produced by clinical experts have been used as the gold standard (which have also been compared among each o...

  2. Numerical Modeling of Ablation Heat Transfer

    Ewing, Mark E.; Laker, Travis S.; Walker, David T.


    A unique numerical method has been developed for solving one-dimensional ablation heat transfer problems. This paper provides a comprehensive description of the method, along with detailed derivations of the governing equations. This methodology supports solutions for traditional ablation modeling including such effects as heat transfer, material decomposition, pyrolysis gas permeation and heat exchange, and thermochemical surface erosion. The numerical scheme utilizes a control-volume approach with a variable grid to account for surface movement. This method directly supports implementation of nontraditional models such as material swelling and mechanical erosion, extending capabilities for modeling complex ablation phenomena. Verifications of the numerical implementation are provided using analytical solutions, code comparisons, and the method of manufactured solutions. These verifications are used to demonstrate solution accuracy and proper error convergence rates. A simple demonstration of a mechanical erosion (spallation) model is also provided to illustrate the unique capabilities of the method.

  3. Deep Dive Topic: Choosing between ablators

    Hurricane, O. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thomas, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Olson, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    Recent data on implosions using identical hohlraums and very similar laser drives underscores the conundrum of making a clear choice of one ablator over another. Table I shows a comparison of Be and CH in a nominal length, gold, 575 μm-diameter, 1.6 mg/cc He gas-fill hohlraum while Table II shows a comparison of undoped HDC and CH in a +700 length, gold, 575 μm diameter, 1.6 mg/cc He gas fill hohlraum. As can be seen in the tables, the net integrated fusion performance of these ablators is the same to within error bars. In the case of the undoped HDC and CH ablators, the hot spot shapes of the implosions were nearly indistinguishable for the experiments listed in Table II.

  4. Ultrafast laser ablation of transparent materials

    Bauer, Lara; Russ, Simone; Kaiser, Myriam; Kumkar, Malte; Faißt, Birgit; Weber, Rudolf; Graf, Thomas


    The present work investigates the influence of the pulse duration and the temporal spacing between pulses on the ablation of aluminosilicate glass by comparing the results obtained with pulse durations of 0.4 ps and 6 ps. We found that surface modifications occur already at fluences below the single pulse ablation threshold and that laser-induced periodic surface structures (LIPSS) emerge as a result of those surface modifications. For 0.4 ps the ablation threshold fluences is lower than for 6 ps. Scanning electron micrographs of LIPSS generated with 0.4 ps exhibit a more periodic and less coarse structure as compared to structures generated with 6 ps. Furthermore we report on the influence of temporal spacing between the pulses on the occurrence of LIPSS and the impact on the quality of the cutting edge. Keywords: LIPSS,

  5. Mapping techniques for atrial fibrillation ablation.

    Sra, Jasbir; Akhtar, Masood


    Atrial fibrillation (AF) is a common arrhythmia. Although significant work still needs to be done, recent advances in understanding the mechanism of AF have led to the development of elegant catheter mapping techniques for ablation of AF. These improved mapping techniques are complemented by an evolution in various imaging and navigational technologies, several of which can now be combined in a process called registration, so that the physician no longer needs to rely solely on a mental image of the anatomy of the left atrium and the pulmonary vein while attempting to ablate the region. Ongoing advances in mapping technique will increase safety and efficacy and it is likely that AF ablation will become the first-line therapy in most patients with this complicated arrhythmia.

  6. Kinetic depletion model for pellet ablation

    Kuteev, Boris V. [State Technical Univ., St. Petersburg (Russian Federation)


    A kinetic model for depletion effect, which determines pellet ablation when the pellet passes a rational magnetic surface, is formulated. The model predicts a moderate decrease of the ablation rate compared with the earlier considered monoenergy versions [1, 2]. For typical T-10 conditions the ablation rate reduces by a reactor of 2.5 when the 1-mm pellet penetrates through the plasma center. A substantial deceleration of pellets -about 15% per centimeter of low shire rational q region; is predicted. Penetration for Low Field Side and High Field Side injections is considered taking into account modification of the electron distribution function by toroidal magnetic field. It is shown that Shafranov shift and toroidal effects yield the penetration length for HFS injection higher by a factor of 1.5. This fact should be taken into account when plasma-shielding effects on penetration are considered. (author)

  7. Laser Thermal Ablation of Thyroid Benign Nodules.

    Shahrzad, Mohammad Karim


    Thermal ablation therapies for benign thyroid nodules have been introduced in recent years to avoid the complications of traditional methods such as surgery. Despite the little complications and the reportedly acceptable efficacy of thermal ablation methods, quite few medical centers have sought the potential benefits of employing them. This paper provides an introduction to the literature, principles and advances of Percutaneous Laser Ablation therapy of thyroid benign nodules, as well as a discussion on its efficacy, complications and future. Several clinical research papers evaluating the thermal effect of laser on the alleviation of thyroid nodules have been reviewed to illuminate the important points. The results of this research can help researchers to advance the approach and medical centers to decide on investing in these novel therapies.

  8. Thermal ablation of liver metastases from colorectal cancer: radiofrequency, microwave and laser ablation therapies.

    Vogl, Thomas J; Farshid, Parviz; Naguib, Nagy N N; Darvishi, Abbas; Bazrafshan, Babak; Mbalisike, Emmanuel; Burkhard, Thorsten; Zangos, Stephan


    Surgery is currently considered the treatment of choice for patients with colorectal cancer liver metastases (CRLM) when resectable. The majority of these patients can also benefit from systemic chemotherapy. Recently, local or regional therapies such as thermal ablations have been used with acceptable outcomes. We searched the medical literature to identify studies and reviews relevant to radiofrequency (RF) ablation, microwave (MW) ablation and laser-induced thermotherapy (LITT) in terms of local progression, survival indexes and major complications in patients with CRLM. Reviewed literature showed a local progression rate between 2.8 and 29.7 % of RF-ablated liver lesions at 12-49 months follow-up, 2.7-12.5 % of MW ablated lesions at 5-19 months follow-up and 5.2 % of lesions treated with LITT at 6-month follow-up. Major complications were observed in 4-33 % of patients treated with RF ablation, 0-19 % of patients treated with MW ablation and 0.1-3.5 % of lesions treated with LITT. Although not significantly different, the mean of 1-, 3- and 5-year survival rates for RF-, MW- and laser ablated lesions was (92.6, 44.7, 31.1 %), (79, 38.6, 21 %) and (94.2, 61.5, 29.2 %), respectively. The median survival in these methods was 33.2, 29.5 and 33.7 months, respectively. Thermal ablation may be an appropriate alternative in patients with CRLM who have inoperable liver lesions or have operable lesions as an adjunct to resection. However, further competitive evaluation should clarify the efficacy and priority of these therapies in patients with colorectal cancer liver metastases.

  9. Safety and efficacy in ablation of premature ventricular contraction: data from the German ablation registry.

    Fichtner, S; Senges, J; Hochadel, M; Tilz, R; Willems, S; Eckardt, L; Deneke, T; Lewalter, T; Dorwarth, U; Reithmann, C; Brachmann, J; Steinbeck, G; Kääb, S


    Patients with frequent premature ventricular contractions (PVCs) are often highly symptomatic with significantly reduced quality-of-life. We evaluated the outcome and success of PVC ablation in patients in the German Ablation Registry. The German Ablation Registry is a nationwide prospective multicenter database of patients who underwent an ablation procedure, initiated by the "Stiftung Institut für Herzinfarktforschung" (IHF), Ludwigshafen, Germany. Data were acquired from March 2007 to May 2011. Patients underwent PVC ablation in the enrolling ablation centers. A total of 408 patients (age 53.5 ± 15 years, 55 % female) undergoing ablation for PVCs were included. 32 % of patients showed a co-existing structural heart disease. Acute ablation success of the procedure was 82 % in the overall patient group. In patients without structural heart disease, acute success was significantly higher compared with patients with structural heart disease (86 vs. 74 %, p = 0.002). All patients were discharged alive after a median of 3 days. No patient suffered an acute myocardial infarction, stroke, or major bleeding. After 12 months' follow-up, 99 % of patients were still alive showing a significant different mortality between patients with structural heart disease compared with those without (2.3 vs. 0 %, p = 0.012). In addition, 76 % of patients showed significantly improved symptoms after 12 months of follow-up. Based on the data from this registry, ablation of PVCs is a safe and efficient procedure with an excellent outcome and improved symptoms after 12 months.

  10. Performance of displacement ventilation in practice

    Naidenov, K.; Pitchurov, G.; Langkilde, Gunnar


    This paper presents results of a field study in offices with displacement ventilation. It comprises detailed physical measurements of the thermal environment and collection of occupants´ response at 227 workplaces. The results, both physical measurements and human response, identified draught...... as the major local discomfort in the rooms with displacement ventilation. Twenty-three percent of the occupants were daily bothered by draught. In some buildings the maintenance personnel tried to improve occupants´ thermal comfort by raising the supply air temperature or office workers themselves blocked...... the diffusers by rearranging the furniture. Half of the surveyed occupants were not satisfied with the indoor air quality. The main conclusion is that displacement ventilation needs careful design and room furnishing in order to ensure a comfortable environment. Occupants must understand the underlying...

  11. Forced displacement and women's security in Colombia.

    Meertens, Donny


    In the protracted Colombian conflict, assistance to internally displaced persons has developed in the context of contradictory political processes. The Colombian government's launching of a transitional justice process in the midst of armed conflict has generated a complex situation displaying both conflict and post-conflict characteristics. The progressive Constitutional Court rulings on internal displacement, in particular the gender-sensitive Auto 092, constitute an attempt to bring together humanitarian interventions and transitional justice measures in a rights-based framework. However, the national government is reluctant to adopt them fully and local realities still hamper their integrated implementation. Displaced women, therefore, remain in an especially vulnerable position. This paper argues that gender-sensitive humanitarian interventions must take into account all of these complexities of scale and political process in order to make legal frameworks more effective at the local level. In these contexts, interventions should pay particular attention to strategies that contribute to transforming pre-existing gender regimes.

  12. Miscible, porous media displacements with density stratification.

    Riaz, Amir; Meiburg, Eckart


    High accuracy, three-dimensional numerical simulations of miscible displacements with gravity override, in both homogeneous and heterogeneous porous media, are discussed for the quarter five-spot configuration. The influence of viscous and gravitational effects on the overall displacement dynamics is described in terms of the vorticity variable. Density differences influence the flow primarily by establishing a narrow gravity layer, in which the effective Peclet number is enhanced due to the higher flow rate. Although this effect plays a dominant role in homogeneous flows, it is suppressed to some extent in heterogeneous displacements. This is a result of coupling between the viscous and permeability vorticity fields. When the viscous wavelength is much larger than the permeability wavelength, gravity override becomes more effective because coupling between the viscous and permeability vorticity fields is less pronounced. Buoyancy forces of a certain magnitude can lead to a pinch-off of the gravity layer, thereby slowing it down.

  13. Overtreatment of displaced midshaft clavicle fractures

    Ban, Ilija; Nowak, Jan; Virtanen, Kaisa


    Background and purpose - The best treatment for displaced clavicle fractures has been debated for decades. Operative treatment has become more common. However, several randomized trials comparing non-operative and operative treatment have not shown any compelling evidence in favor of surgery. We...... identified the preferred treatment of displaced midshaft clavicle fractures at public hospitals in 3 countries in Scandinavia. Patients and methods - A purpose-made multiple-choice questionnaire in English was sent to all public hospitals in Denmark, Sweden, and Finland. This was addressed to the orthopedic...... surgeon responsible for treatment of clavicle fractures, and completed questionnaires were obtained from 85 of 118 hospitals. Results - In the 3 countries, 69 of the 85 hospitals that responded would treat displaced clavicle fractures operatively. Clear criteria for treatment allocation were used at 58...

  14. Ablative Rocket Deflector Testing and Computational Modeling

    Allgood, Daniel C.; Lott, Jeffrey W.; Raines, Nickey


    A deflector risk mitigation program was recently conducted at the NASA Stennis Space Center. The primary objective was to develop a database that characterizes the behavior of industry-grade refractory materials subjected to rocket plume impingement conditions commonly experienced on static test stands. The program consisted of short and long duration engine tests where the supersonic exhaust flow from the engine impinged on an ablative panel. Quasi time-dependent erosion depths and patterns generated by the plume impingement were recorded for a variety of different ablative materials. The erosion behavior was found to be highly dependent on the material s composition and corresponding thermal properties. For example, in the case of the HP CAST 93Z ablative material, the erosion rate actually decreased under continued thermal heating conditions due to the formation of a low thermal conductivity "crystallization" layer. The "crystallization" layer produced near the surface of the material provided an effective insulation from the hot rocket exhaust plume. To gain further insight into the complex interaction of the plume with the ablative deflector, computational fluid dynamic modeling was performed in parallel to the ablative panel testing. The results from the current study demonstrated that locally high heating occurred due to shock reflections. These localized regions of shock-induced heat flux resulted in non-uniform erosion of the ablative panels. In turn, it was observed that the non-uniform erosion exacerbated the localized shock heating causing eventual plume separation and reversed flow for long duration tests under certain conditions. Overall, the flow simulations compared very well with the available experimental data obtained during this project.

  15. Radiofrequency ablation for treatment of atrial fibrillation.

    Safaei, Nasser; Montazerghaem, Hossein; Azarfarin, Rasoul; Alizadehasl, Azin; Alikhah, Hossein


    Atrial Fibrillation (AF) is the most common cardiac arrhythmia which represents a major public health problem. The main purpose of this research is to evaluate the Radiofrequency (RF) ablation effects in the patients with chronic AF scheduled for cardiac surgery because of different heart diseases. The descriptive and prospective study was conducted on 60 patients with AF scheduled for surgery along with RF ablation. The data were collected by questionnaire and included: patients' age, sex, NYHA class, operation type, past medical history, type and cause of valvular heart disease, preoperative ECG (electrocardiogram), duration of surgery, clamping time, cardiopulmonary bypass, and RF ablation time. RF ablation was followed by the main operation. The follow up examination, ECG, and echocardiography were performed 3 and 6 months after operation. The mean age of patients was 48±10 years (18-71 years). Forty one patients had permanent AF and 19 had the persistent AF. The left ventricular ejection fraction was 48.27±9.75 percent before operation, and reached to 56.27±7.87 percent after the surgery (P<0.001). The mean NYHA class before the surgery was 2.83±0.68 which decreased to 1.34±0.46 6 months after the surgery with RF ablation (P<0.001). One patient (1.6%) died after surgery. Complete relief and freedom from AF recurrence was observed in 70% of patients in the mean follow up in 7 months after the surgery. The sinus rhythm with efficient atrial contraction was established in 100% of discharged patients. RF ablation is an effective procedure to cure atrial fibrillation in patients undergoing cardiac surgeries.

  16. Thermal Ablation for Benign Thyroid Nodules: Radiofrequency and Laser

    Baek, Jung Hwan; Lee, Jeong Hyun [University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Valcavi, Roberto [Endocrinology Division and Thyroid Disease Center, Arcispedale Santa Maria Nuova, Reggio Emilia (Italy); Pacella, Claudio M. [Diagnostic Imaging and Interventional Radiology Department, Ospedale Regina Apostolorum, Albano Laziale-Rome (IT); Rhim, Hyun Chul [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Na, Dong Kyu [Human Medical Imaging and Intervention Center, Seoul (Korea, Republic of)


    Although ethanol ablation has been successfully used to treat cystic thyroid nodules, this procedure is less effective when the thyroid nodules are solid. Radiofrequency (RF) ablation, a newer procedure used to treat malignant liver tumors, has been valuable in the treatment of benign thyroid nodules regardless of the extent of the solid component. This article reviews the basic physics, techniques, applications, results, and complications of thyroid RF ablation, in comparison to laser ablation.

  17. Stereotactic Body Radiotherapy and Ablative Therapies for Lung Cancer.

    Abbas, Ghulam; Danish, Adnan; Krasna, Mark J


    The treatment paradigm for early stage lung cancer and oligometastatic disease to the lung is rapidly changing. Ablative therapies, especially stereotactic body radiation therapy, are challenging the surgical gold standard and have the potential to be the standard for operable patients with early stage lung cancer who are high risk due to co- morbidities. The most commonly used ablative modalities include stereotactic body radiation therapy, microwave ablation, and radiofrequency ablation.

  18. Subcellular analysis by laser ablation electrospray ionization mass spectrometry

    Vertes, Akos; Stolee, Jessica A; Shrestha, Bindesh


    In various embodiments, a method of laser ablation electrospray ionization mass spectrometry (LAESI-MS) may generally comprise micro-dissecting a cell comprising at least one of a cell wall and a cell membrane to expose at least one subcellular component therein, ablating the at least one subcellular component by an infrared laser pulse to form an ablation plume, intercepting the ablation plume by an electrospray plume to form ions, and detecting the ions by mass spectrometry.



    A novel variable displacement compressor (VDC) for automotive air conditioner (AAC) is introduced, which inherits the advantages of common wobble plate type VDC. It has fewer parts and makes less noise, and inst ead of pneumatic valve the displacement is controlled by electronic control valv e. In order to know the control mechanism well and get a good control effect, a mathematical model for the variable displacement mechanism is developed accordin g to the geometrical and kinematical information of the compressor. Using the mo del, the effect of relevant parameters on variable displace control is estimated . It is helpful to make the optimum decision in the flow control of AAC. As the novel displacement control device, the structure and control rule of electronic control valve is introduced. It can get better effect than the conventional pneu matic valves. And by using this new electronic control device, the optimum syste mic control of AAC is available.

  20. Ablation of carbide materials with femtosecond pulses

    Dumitru, Gabriel; Romano, Valerio; Weber, Heinz P.; Sentis, Marc; Marine, Wladimir


    The response of cemented tungsten carbide and of titanium carbonitride was investigated with respect to damage and ablation properties, under interaction with ultrashort laser pulses. These carbide materials present high microhardness and are of significant interest for tribological applications. The experiments were carried out in air with a commercial Ti:sapphire laser at energy densities on the target up to 6.5 J/cm 2. The irradiated target surfaces were analyzed with optical, SEM and AFM techniques and the damage and ablation threshold values were determined using the measured spot diameters and the calculated incident energy density distributions.

  1. Testing of Advanced Conformal Ablative TPS

    Gasch, Matthew; Agrawal, Parul; Beck, Robin


    In support of the CA250 project, this paper details the results of a test campaign that was conducted at the Ames Arcjet Facility, wherein several novel low density thermal protection (TPS) materials were evaluated in an entry like environment. The motivation for these tests was to investigate whether novel conformal ablative TPS materials can perform under high heat flux and shear environment as a viable alternative to rigid ablators like PICA or Avcoat for missions like MSL and beyond. A conformable TPS over a rigid aeroshell has the potential to solve a number of challenges faced by traditional rigid TPS materials (such as tiled Phenolic Impregnated Carbon Ablator (PICA) system on MSL, and honeycomb-based Avcoat on the Orion Multi Purpose Crew Vehicle (MPCV)). The compliant (high strain to failure) nature of the conformable ablative materials will allow better integration of the TPS with the underlying aeroshell structure and enable monolithic-like configuration and larger segments to be used in fabrication.A novel SPRITE1 architecture, developed by the researchers at NASA Ames was used for arcjet testing. This small probe like configuration with 450 spherecone, enabled us to test the materials in a combination of high heat flux, pressure and shear environment. The heat flux near the nose were in the range of 500-1000 W/sq cm whereas in the flank section of the test article the magnitudes were about 50 of the nose, 250-500W/sq cm range. There were two candidate conformable materials under consideration for this test series. Both test materials are low density (0.28 g/cu cm) similar to Phenolic Impregnated Carbon Ablator (PICA) or Silicone Impregnated Refractory Ceramic Ablator (SIRCA) and are comprised of: A flexible carbon substrate (Carbon felt) infiltrated with an ablative resin system: phenolic (Conformal-PICA) or silicone (Conformal-SICA). The test demonstrated a successful performance of both the conformable ablators for heat flux conditions between 50

  2. Passive Smoking in a Displacement Ventilated Room

    Bjørn, Erik; Nielsen, Peter V.

    The aim of this research is to see if the displacement ventilation principle can protect a person from exposure to passive tobacco smoking. This is done by full-scale experiments with two breathing thermal manikins, smoke visualisations, and tracer gas measurements. In some situations, exhaled...... smoke will stratify in a certain height due to the vertical temperature gradient. This horizontal layer of exhaled tobacco smoke may lead to exposure. In other situations, the smoke is mixed into the upper zone, and the passive smoker is protected to some extent by the displacement principle...

  3. Maxillary tooth displacement in the infratemporal fossa.

    Roshanghias, Korosh; Peisker, Andre; Zieron, Jörg Olaf


    Wisdom tooth operations are sometimes accompanied by complications. This case report shows complications during upper jaw third molar removal. Expectable problems during oral surgery should be planned to be solved in advance. Displacement of the third molar during oral surgeries as a considerable complication is rarely discussed scientifically. A good design of flap, adequate power for extraction, and clear view on the surgical field are crucial. Three-dimensional radiographic diagnostics in terms of cone beam computed tomography is helpful after tooth displacement into the infratemporal fossa.

  4. Maxillary tooth displacement in the infratemporal fossa

    Korosh Roshanghias


    Full Text Available Wisdom tooth operations are sometimes accompanied by complications. This case report shows complications during upper jaw third molar removal. Expectable problems during oral surgery should be planned to be solved in advance. Displacement of the third molar during oral surgeries as a considerable complication is rarely discussed scientifically. A good design of flap, adequate power for extraction, and clear view on the surgical field are crucial. Three-dimensional radiographic diagnostics in terms of cone beam computed tomography is helpful after tooth displacement into the infratemporal fossa.

  5. Bucket Foundation Response Under Various Displacement Rates

    Vaitkunaite, Evelina; Nielsen, Benjaminn Nordahl; Ibsen, Lars Bo


    in a multi-bucket foundation system. The foundation model is at a scale of approximately 1:20 prototype foundation size. The tests are performed in a pressure tank with the foundation model installed in dense sand. Based on the data, the conclusion is that the bucket foundation design in a storm case should......The present testing program aims at showing the pore pressure response around a bucket foundation skirt as well as the load and displacement change due to ten different displacement rates. Research findings are useful for a numerical model calibration focusing on the design of the upwind foundation...

  6. The Costs of Displacement in Brazil

    Naercio Menezes-Filho


    This paper uses new data that combines information on workers’ education and earnings trajectories with information about their firms to estimate the costs of job displacement in Brazil. We find that high-tenure workers displaced from their firms during mass lay-offs suffer a long-term loss in monthly wages of about 20% per year. We show that this result is robust to different treatment of workers that leave the formal sector of the economy and is driven by the losses suffered by more educa...

  7. Histone displacement during nucleotide excision repair

    Dinant, C.; Bartek, J.; Bekker-Jensen, S.


    Nucleotide excision repair (NER) is an important DNA repair mechanism required for cellular resistance against UV light and toxic chemicals such as those found in tobacco smoke. In living cells, NER efficiently detects and removes DNA lesions within the large nuclear macromolecular complex called...... of histone variants and histone displacement (including nucleosome sliding). Here we review current knowledge, and speculate about current unknowns, regarding those chromatin remodeling activities that physically displace histones before, during and after NER. © 2012 by the authors; licensee MDPI, Basel...

  8. Efficacy and satisfaction rate comparing endometrial ablation by rollerball electrocoagulation to uterine balloon thermal ablation in a randomised controlled trial.

    Zon-Rabelink, I.A.A. van; Vleugels, M.P.; Merkus, J.M.W.M.; Graaf, R.M. de


    OBJECTIVE: To compare two methods of endometrial ablation, hysteroscopic rollerball electrocoagulation (RBE) and non-hysteroscopic uterine balloon thermal ablation (Thermachoice trade mark ), regarding efficacy for reducing dysfunctional uterine bleeding and patients satisfaction rate. METHODS: A ra

  9. National survey of catheter ablation for atrial fibrillation: The Japanese catheter ablation registry of atrial fibrillation (J-CARAF

    Koichi Inoue


    Conclusions: Ipsilateral encircling PVI, using 3D mapping and irrigated-tip catheters, is the standard AF ablation method in Japan. However, adjunctive ablations were performed frequently, even in patients with paroxysmal AF.

  10. Experimental measurement of ablation effects in plasma armature railguns

    Parker, J.V.; Parsons, W.M.


    Experimental evidence supporting the importance of ablation in plasma armature railguns is presented. Experiments conducted using the HYVAX and MIDI-2 railguns are described. Several indirect effects of ablation are identified from the experimental results. An improved ablation model of plasma armature dynamics is proposed which incorporates the restrike process.

  11. Cardiac ablation by transesophageal high intensity focused ultrasound

    JIANG Chen-xi; YU Rong-hui; MA Chang-sheng


    @@ Cardiac ablation is an important modality of invasive therapy in modern cardiology, especially in the treatment of arrhythmias, as well as other diseases such as hypertrophic obstructive cardiomyopathy (HOCM). Since Huang et al1 used radiofrequency (RF) to ablate canine atrial ventricular junction, RF has developed into the leading energy source in catheter ablation of arrhythmias.

  12. Monitoring of tumor radio frequency ablation using derivative spectroscopy

    Spliethoff, J.W.; Tanis, E.; Evers, Daniel James; Hendriks, B.H.; Prevoo, W.; Ruers, T.J.M.


    Despite the widespread use of radio frequency (RF) ablation, an effective way to assess thermal tissue damage during and after the procedure is still lacking. We present a method for monitoring RF ablation efficacy based on thermally induced methemoglobin as a marker for full tissue ablation. Diffus

  13. Meteor Ablation as Origin for the D-region Ledge in Electrical Conductivity

    Williams, E. R.; Wu, Y. J.; Friedrich, M.; Hsu, R. R.


    The ledge in electron density and electrical conductivity in the 80-90 km altitude range has been a consistent feature in rocket and electromagnetic observations of the D-region for half a century. Most conspicuous at nighttime and at low latitudes, the abrupt increase in electron density with altitude near 85 km often shows a scale height of less than 1 km. This observed behavior is a marked departure from the Wait-Spies exponential profile that is often used to model the D-region. Calculations show that the conduction current and displacement current are matched at the height of the observed ledge over a wide range of VLF frequencies, pinning this altitude as the sharp boundary for the global VLF waveguide. Meteor ablation involves the abrupt transformation in altitude of faint sub-millimeter-sized meteoroids to nanometer-sized dust, when the meteor boiling temperature near 2100K is attained. The ablation dust can reach concentrations comparable to electron density near the ledge height and in the polluted continental boundary layer. The electron affinity of this silicate mineral dust together with the suppression of negative molecular ions (e.g., O2- ) by monatomic O (Plane et al., 2014), serves to reduce the free electron concentration to form the ledge in conductivity. Calculations with the classical model for meteor ablation require a mean incoming meteor speed of 15 km/s. with rapid decline at higher speeds, to produce a ledge height at 85 km altitude. The key role for meteor ablation in this ionosphere context has likely not received due recognition because neither the meteoric dust nor the meteors that create it are readily detectable by remote sensing, and in situ observations of the mesosphere are scarce.

  14. 24 CFR 42.350 - Relocation assistance for displaced persons.


    ... described in 49 CFR part 24. A displaced person must be advised of his or her rights under the Fair Housing... of 1974 § 42.350 Relocation assistance for displaced persons. A displaced person may choose to... safety of the person or the public; or (2) The person is displaced from a “lower-income dwelling...

  15. 24 CFR 92.353 - Displacement, relocation, and acquisition.


    ... U.S.C. 4201-4655) and 49 CFR part 24. A “displaced person” must be advised of his or her rights... assistance for displaced persons—(1) General. A displaced person (defined in paragraph (c)(2) of this section..., safe, and sanitary replacement dwellings not located in such areas. (2) Displaced Person. (i)...

  16. 24 CFR 882.810 - Displacement, relocation, and acquisition.


    ... CFR 24.2(g)(2); or (iv) HUD determines that the person was not displaced as a direct result of... section. (c) Relocation assistance for displaced persons. A “displaced person” (defined in paragraph (g... displaced person must be advised of his or her rights under the Fair Housing Act (42 U.S.C. 3601-19) and,...

  17. A Personal Appearance Program for Displaced Homemakers.

    Fiore, Ann Marie; De Long, Marilyn Revell


    A career counseling program evaluated the self-esteem of 28 displaced homemakers, then presented 3 sessions on the importance of personal appearance in hiring practices, wardrobe management, nonverbal communication, professional image, and self-concept. Analysis of participant evaluations indicated improved levels of control and confidence and…

  18. A new method for angular displacement measurement

    Caini Zhang(张彩妮); Xiangzhao Wang(王向朝)


    We describe a new method for angular displacement measurements that is based on a Fabry-Perot inter-ferometer. A measurement accuracy of 10-s rad is obtained by use of the sinusoidal phase modulatinginterferometry. Another Fabry-Perot interferometer is used to obtain the key initial angle of incidence.

  19. Displacement pile installation effects in sand

    Beijer-Lundberg, A.


    Installation effects govern the post-installation behaviour of displacement piles in sand. These effects are currently not completely understood. Suitable experimental techniques to model these installation effects include field, laboratory and experimental models. In the current thesis a small-scal

  20. Heterodyne displacement interferometer, insensitive for input polarization

    Meskers, A.J.H.; Spronck, J.W.; Munnig Schmidt, R.H.


    Periodic nonlinearity (PNL) in displacement interferometers is a systematic error source that limits measurement accuracy. The PNL of coaxial heterodyne interferometers is highly influenced by the polarization state and orientation of the source frequencies. In this Letter, we investigate this error

  1. Displacement Ventilation by Different Types of Diffusers

    Nielsen, Peter V.; Hoff, Lars; Pedersen, Lars Germann

    The paper describes measuring results of the air movement from three different types of diffusers for displacement ventilation. Two of the diffusers are lowlevel wall mounted diffusers, one with a low and one with a high initial entrainment. The third diffuser is of the floor mounted type....

  2. Education: protecting the rights of displaced children

    Suba Mahalingam


    Full Text Available UNICEF and its partners work with displaced communitiesto provide material assistance and protection, using as their basis the UN Convention on the Rights of the Child1 and other internationallegal instruments. Education has proven a valuable tool in this effort, not only making children aware of their rights but also providing a way to participate in the realisation of these rights.

  3. Displacing Media: LCD LAB Artistic Residency

    Filipe Pais


    Full Text Available This review refers to an artistic residency which took place at LCD LAB -  CAAA at Guimarães, in March, exploring a strategy for media art called Media Displacement. The text introduces the strategy very briefly and describes the residency's organization, structure, processses and the results produced.

  4. Olympic scale of sport-induced displacement

    Jean du Plessis


    Full Text Available The Olympic Games have displaced more than two million people in the last 20 years, disproportionately affecting particular groups such as the homeless, the poor, Roma and African-Americans. Mega-events such as the Olympic Games often leave a negative housing legacy for local populations.

  5. Comb-drive actuators for large displacements

    Legtenberg, Rob; Groeneveld, A.W.; Elwenspoek, M.


    The design, fabrication and experimental results of lateral-comb-drive actuators for large displacements at low driving voltages is presented. A comparison of several suspension designs is given, and the lateral large deflection behaviour of clamped - clamped beams and a folded flexure design is mod

  6. Britain's Redundancy Payments for Displaced Workers.

    Root, Lawrence S.


    The Redundancy Payments Act of 1965 established the idea that an employee has property rights to a job based on years of company service. It instituted an entitlement program for displaced workers sponsored by firms and the government. The British layoff situtation differs from that of the United States. (Author/CH)

  7. Environmental conditions in displaced communities of Khartoum ...


    one quarter of all deaths and of the total disease burden and slightly more than one-third for children can be attributed to the ..... characteristics in Khartoum State displaced communities, 2013. (N = 662). ... Donkeys/Horses. 18. 2.7. Others. 72.

  8. A review of the safety aspects of radio frequency ablation

    Abhishek Bhaskaran


    Full Text Available In light of recent reports showing high incidence of silent cerebral infarcts and organized atrial arrhythmias following radiofrequency (RF atrial fibrillation (AF ablation, a review of its safety aspects is timely. Serious complications do occur during supraventricular tachycardia (SVT ablations and knowledge of their incidence is important when deciding whether to proceed with ablation. Evidence is emerging for the probable role of prophylactic ischemic scar ablation to prevent VT. This might increase the number of procedures performed. Here we look at the various complications of RF ablation and also the methods to minimize them. Electronic database was searched for relevant articles from 1990 to 2015. With better awareness and technological advancements in RF ablation the incidence of complications has improved considerably. In AF ablation it has decreased from 6% to less than 4% comprising of vascular complications, cardiac tamponade, stroke, phrenic nerve injury, pulmonary vein stenosis, atrio-esophageal fistula (AEF and death. Safety of SVT ablation has also improved with less than 1% incidence of AV node injury in AVNRT ablation. In VT ablation the incidence of major complications was 5–11%, up to 3.4%, up to 1.8% and 4.1–8.8% in patients with structural heart disease, without structural heart disease, prophylactic ablations and epicardial ablations respectively. Vascular and pericardial complications dominated endocardial and epicardial VT ablations respectively. Up to 3% mortality and similar rates of tamponade were reported in endocardial VT ablation. Recent reports about the high incidence of asymptomatic cerebral embolism during AF ablation are concerning, warranting more research into its etiology and prevention.

  9. Ultrasound-guided percutaneous thermal ablation of hepatocellular carcinoma using microwave and radiofrequency ablation

    Xu, H.-X.; Xie, X.-Y.; Lu, M.-D. E-mail:; Chen, J.-W.; Yin, X.-Y.; Xu, Z.-F.; Liu, G.-J


    AIM: To investigate the therapeutic efficacy of thermal ablation for treatment of hepatocellular carcinoma (HCC) using microwave and radiofrequency (RF) energy application. MATERIALS AND METHODS: A total of 190 nodules in 97 patients (84 male, 13 female; mean age 53.4 years, range 24-74 years) with HCC were treated with microwave or RF ablation in the last 4 years. The applicators were introduced into the tumours under conscious analgesic sedation by intravenous administration of fentanyl citrate and droperidol and local anaesthesia in both thermal ablation procedures. The patients were then followed up with contrast-enhanced computed tomography (CT) to evaluate treatment response. Survival was analysed using the Kaplan-Meier method. RESULTS: Complete ablation was obtained in 92.6% (176/190) nodules. The complete ablation rates were 94.6% (106/112) in microwave ablation and 89.7% (70/78) in RF ablation. The complete ablation rates in tumours{<=}2.0, 2.1-3.9 and {>=}4.0 cm were 93.1, 93.8 and 86.4%, respectively. Local recurrence was found in 9.5% nodules and the rates in tumours{<=}2.0, 2.1-3.9 and {>=}4.0 cm in diameter were 3.4, 9.9 and 31.8%, respectively. In the follow-up period, 7.1% nodules ablated by microwave and 12.8% by RF presented local recurrence. The 1, 2 and 3-year distant recurrence-free survivals were 47.2, 34.9 and 31.0%, respectively. Estimated mean survival was 32 months, and 1, 2 and 3-year cumulative survivals were 75.6, 58.5, and 50.0%, respectively. One and 2 years survivals of Child-Pugh class A, B and C patients were 83.8 and 70.4%, 78.2 and 53.2%, 36.3 and 27.3%, respectively. CONCLUSION: Thermal ablation therapy by means of microwave and RF energy application is an effective and safe therapeutic technique for hepatocellular carcinoma. Large tumours can be completely ablated, but have a significantly higher risk of local recurrence at follow-up.

  10. Diagnostics of laser ablated plasma plumes

    Amoruso, S.; Toftmann, B.; Schou, Jørgen;


    The effect of an ambient gas on the expansion dynamics of laser ablated plasmas has been studied for two systems by exploiting different diagnostic techniques. First, the dynamics of a MgB2 laser produced plasma plume in an Ar atmosphere has been investigated by space-and time-resolved optical...

  11. Ablation Resistant Zirconium and Hafnium Ceramics

    Bull, Jeffrey (Inventor); White, Michael J. (Inventor); Kaufman, Larry (Inventor)


    High temperature ablation resistant ceramic composites have been made. These ceramics are composites of zirconium diboride and zirconium carbide with silicon carbide, hafnium diboride and hafnium carbide with silicon carbide and ceramic composites which contain mixed diborides and/or carbides of zirconium and hafnium. along with silicon carbide.

  12. UV laser ablation patterns in intraocular lenses

    Lagiou, D. P.; Evangelatos, Ch.; Apostolopoulos, A.; Spyratou, E.; Bacharis, C.; Makropoulou, M.; Serafetinides, A. A.


    The aim of this work is to investigate the effect of UV solid state laser radiation on intraocular lens (IOL) polymer surfaces as an alternative method to conventional surface shaping techniques for IOLs customization. Laser ablation experiments were performed on PMMA plates and commercially available hydrophobic and hydrophilic acrylic IOLs with the 5th harmonic of a Q-switched Nd:YAG laser (λ=213 nm). Circular arrays of holes were drilled on the polymer surface, covering the centre and the peripheries of the IOL. The morphology of the ablated IOL surface was examined with a conventional optical microscope (Leitz GMBH Wetzlar) and with a scanning electron microscope (SEM, Fei - Innova Nanoscope) at various laser parameters. Quantitative measurements of ablation rates were performed with a contact profilometer (Dektak-150), in which a mechanical stylus scanned across the surface of gold-coated IOLs (after SEM imaging) to measure variationsF in surface height. Laser interaction with IOLs depends on optical and mechanical material properties, in addition to laser radiation parameters. The exact ablation mechanism is discussed. Some polymer materials, depending on their properties, are more susceptible to the photothermal mechanism than the photochemical one or vice versa. In summary, every IOL polymer exhibits specific attributes in its interaction with the 5th harmonic of Nd:YAG laser.

  13. Combining Electrolysis and Electroporation for Tissue Ablation.

    Phillips, Mary; Rubinsky, Liel; Meir, Arie; Raju, Narayan; Rubinsky, Boris


    Electrolytic ablation is a method that operates by delivering low magnitude direct current to the target region over long periods of time, generating electrolytic products that destroy cells. This study was designed to explore the hypothesis stating that electrolytic ablation can be made more effective when the electrolysis-producing electric charges are delivered using electric pulses with field strength typical in reversible electroporation protocols. (For brevity we will refer to tissue ablation protocols that combine electroporation and electrolysis as E(2).) The mechanistic explanation of this hypothesis is related to the idea that products of electrolysis generated by E(2) protocols can gain access to the interior of the cell through the electroporation permeabilized cell membrane and therefore cause more effective cell death than from the exterior of an intact cell. The goal of this study is to provide a first-order examination of this hypothesis by comparing the charge dosage required to cause a comparable level of damage to a rat liver, in vivo, when using either conventional electrolysis or E(2) approaches. Our results show that E(2) protocols produce tissue damage that is consistent with electrolytic ablation. Furthermore, E(2) protocols cause damage comparable to that produced by conventional electrolytic protocols while delivering orders of magnitude less charge to the target tissue over much shorter periods of time.

  14. Modeling sublimation of a charring ablator

    Balhoff, J. F.; Pike, R. W.


    The Hertz-Knudsen analysis is shown to accurately predict the sublimation rate from a charring ablator. Porosity is shown to have a significant effect on the surface temperature. The predominant carbon species found in the vapor is C3, which agrees well with the results of previous investigations.

  15. Bending diamonds by femtosecond laser ablation

    Balling, Peter; Esberg, Jakob; Kirsebom, Kim;


    We present a new method based on femtosecond laser ablation for the fabrication of statically bent diamond crystals. Using this method, curvature radii of 1 m can easily be achieved, and the curvature obtained is very uniform. Since diamond is extremely tolerant to high radiation doses, partly due...

  16. Outpatient laser tonsillar ablation under local anaesthetic.

    Andrews, Peter J; Latif, Abdul


    Outpatient laser ablation of the palatine tonsils under local anaesthetic is an alternative technique to capsular tonsillectomy for recurrent tonsillitis under general anaesthetic. Laser tonsillotomy ablates up to 70% of the tonsillar tissue and is performed when patients choose not to have a conventional tonsillectomy, or are unfit for a general anaesthetic. The technique described here is an adaptation of Krespis' laser-assisted serial tonsillectomy (LAST) whereby only one sitting is required. Krespis' technique effectively eliminates recurrent tonsillitis in 96% of the cases over a 4-year follow-up period and represents the only substantial study looking at treating recurrent tonsillitis with outpatient laser ablation. This study is a retrospective postal survey of 19 patients who underwent laser tonsillar ablation under local anaesthetic for recurrent chronic tonsillitis from 1997 to 2001 and was performed in liaison with the clinical audit department at Basildon Hospital. We had a response rate of 74% and an admission rate of 0%, which compares favourably with day case tonsillectomy surgery. Of the patients, 75% did not experience further episodes of tonsillitis 12 months after the procedure and 77% of the patients were glad they had the operation. Although this technique does not completely eliminate tonsillitis, it offers an alternative for those patients who prefer a procedure that is done quickly in an outpatient setting without the additional problems of general anaesthesia, overnight hospital admission and long waiting lists.

  17. Imaging in percutaneous ablation for atrial fibrillation

    R. Maksimović (Ružica); T. Dill (Thorsten); A.D. Ristić (Arsen); P.M. Seferovic (Petar)


    textabstractPercutaneous ablation for electrical disconnection of the arrhythmogenic foci using various forms of energy has become a well-established technique for treating atrial fibrillation (AF). Success rate in preventing recurrence of AF episodes is high although associated with a significant

  18. Barium Ferrite Films Grown by Laser Ablation

    Lisfi, A.; Lodder, J.C.; Haan, de P.; Smithers, M.A.; Roesthuis, F.J.G.


    Pulsed laser ablation (PLA) has been used to grow barium ferrite films on Al2O3 single crystal substrates. When deposition occurs in an oxidising atmosphere at high temperatures, the films are single BaFe12O19 phase, very well oriented with (001) texture, and exhibit a large perpendicular magnetic a

  19. Unanswered Questions in Complex Fractionated Atrial Electrogram Ablation.

    Aksu, Tolga; Guler, Tümer Erdem; Yalin, Kivanc; Oto, Ali


    Pulmonary vein isolation has been accepted as potential target for ablation of paroxysmal atrial fibrillation (AF) given that the pulmonary veins are the main source of AF triggers. However, ablation strategies for persistent AF are less well defined. Mapping and ablation of complex fractionated atrial electrograms (CFAEs) is one strategy that has been proposed as a strategy for substrate modification although there is no consensus on their definition and procedural end points. Results of clinical studies have been conflicting. In this review, we aimed to discuss yesterday, today, and tomorrow of CFAEs ablation in persistent AF ablation. © 2016 Wiley Periodicals, Inc.

  20. Plume collimation for laser ablation electrospray ionization mass spectrometry

    Vertes, Akos; Stolee, Jessica A.


    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  1. Tissue tearing caused by pulsed laser-induced ablation pressure.

    Cummings, J P; Walsh, J T


    Pressure induced by ablative pulses of laser radiation is shown to correlate with the mechanical disruption of tissue. The ablation pressure induced during Er:YSGG laser irradiation of skin, liver, and aorta was calculated from a ballistic pendulum-based measurement of recoil momentum. The ejected material and ablation crater were examined grossly and microscopically after ablation. A gas-dynamic model of laser-induced vaporization was used to understand the measured pressures. The results show that mechanical disruption of tissue occurs when the ablation pressure exceeds the strength of the irradiated tissue at sites of intrinsic weakness.

  2. Plume collimation for laser ablation electrospray ionization mass spectrometry

    Vertes, Akos; Stolee, Jessica A.


    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  3. Plume collimation for laser ablation electrospray ionization mass spectrometry

    Vertes, Akos; Stolee, Jessica A.


    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  4. Thermochemical Ablation Analysis of the Orion Heatshield

    Sixel, William


    The Orion Multi-Purpose Crew Vehicle will one day carry astronauts to the Moon and beyond, and Orion's heatshield is a critical component in ensuring their safe return to Earth. The Orion heatshield is the structural component responsible for absorbing the intense heating environment caused by re-entry to Earth's atmosphere. The heatshield is primarily composed of Avcoat, an ablative material that is consumed during the re-entry process. Ablation is primarily characterized by two processes: pyrolysis and recession. The decomposition of in-depth virgin material is known as pyrolysis. Recession occurs when the exposed surface of the heatshield reacts with the surrounding flow. The Orion heatshield design was changed from an individually filled Avcoat honeycomb to a molded block Avcoat design. The molded block Avcoat heatshield relies on an adhesive bond to keep it attached to the capsule. In some locations on the heatshield, the integrity of the adhesive bond cannot be verified. For these locations, a mechanical retention device was proposed. Avcoat ablation was modelled in CHAR and the in-depth virgin material temperatures were used in a Thermal Desktop model of the mechanical retention device. The retention device was analyzed and shown to cause a large increase in the maximum bondline temperature. In order to study the impact of individual ablation modelling parameters on the heatshield sizing process, a Monte Carlo simulation of the sizing process was proposed. The simulation will give the sensitivity of the ablation model to each of its input parameters. As part of the Monte Carlo simulation, statistical uncertainties on material properties were required for Avcoat. Several properties were difficult to acquire uncertainties for: the pyrolysis gas enthalpy, non-dimensional mass loss rate (B´c), and Arrhenius equation parameters. Variability in the elemental composition of Avcoat was used as the basis for determining the statistical uncertainty in pyrolysis gas

  5. A chemical model of meteoric ablation

    T. Vondrak


    Full Text Available Most of the extraterrestrial dust entering the Earth's atmosphere ablates to produce metal vapours, which have significant effects on the aeronomy of the upper mesosphere and lower thermosphere. A new Chemical Ablation Model (CAMOD is described which treats the physics and chemistry of ablation, by including the following processes: sputtering by inelastic collisions with air molecules before the meteoroid melts; evaporation of atoms and oxides from the molten particle; diffusion-controlled migration of the volatile constituents (Na and K through the molten particle; and impact ionization of the ablated fragments by hyperthermal collisions with air molecules. Evaporation is based on thermodynamic equilibrium in the molten meteoroid (treated as a melt of metal oxides, and between the particle and surrounding vapour phase. The loss rate of each element is then determined assuming Langmuir evaporation. CAMOD successfully predicts the meteor head echo appearance heights, observed from incoherent scatter radars, over a wide range of meteoroid velocities. The model also confirms that differential ablation explains common-volume lidar observations of K, Ca and Ca+ in fresh meteor trails. CAMOD is then used to calculate the injection rates into the atmosphere of a variety of elements as a function of altitude, integrated over the meteoroid mass and velocity distributions. The most abundant elements (Fe, Mg and Si have peak injection rates around 85 km, with Na and K about 8 km higher. The more refractory element Ca ablates around 82 km with a Na:Ca ratio of 4:1, which does therefore not explain the depletion of atomic Ca to Na, by more than 2 orders of magnitude, in the upper mesosphere. Diffusion of the most volatile elements (Na and K does not appear to be rate-limiting except in the fastest meteoroids. Non-thermal sputtering causes ~35% mass loss from the fastest (~60–70 km s−1 and smallest (10−17–10

  6. A chemical model of meteoric ablation

    T. Vondrak


    Full Text Available Most of the extraterrestrial dust entering the Earth's atmosphere ablates to produce metal vapours, which have significant effects on the aeronomy of the upper mesosphere and lower thermosphere. A new Chemical Ablation Model (CAMOD is described which treats the physics and chemistry of ablation, by including the following processes: sputtering by inelastic collisions with air molecules before the meteoroid melts; evaporation of atoms and oxides from the molten particle; diffusion-controlled migration of the volatile constituents (Na and K through the molten particle; and impact ionization of the ablated fragments by hyperthermal collisions with air molecules. Evaporation is based on thermodynamic equilibrium in the molten meteoroid (treated as a melt of metal oxides, and between the particle and surrounding vapour phase. The loss rate of each element is then determined assuming Langmuir evaporation. CAMOD successfully predicts the meteor head echo appearance heights, observed from incoherent scatter radars, over a wide range of meteoroid velocities. The model also confirms that differential ablation explains common-volume lidar observations of K, Ca and Ca+ in fresh meteor trails. CAMOD is then used to calculate the injection rates into the atmosphere of a variety of elements as a function of altitude, integrated over the meteoroid mass and velocity distributions. The most abundant elements (Fe, Mg and Si have peak injection rates around 85 km, with Na and K about 8 km higher. The more refractory element Ca ablates around 82 km with a Na:Ca ratio of 4:1, which does therefore not explain the depletion of atomic Ca to Na, by more than 2 orders of magnitude, in the upper mesosphere. Diffusion of the most volatile elements (Na and K does not appear to be rate-limiting except in the fastest meteoroids. Non-thermal sputtering causes ~35% mass loss from the fastest (~60–70 km s−1 and smallest (10−17–10

  7. Burn, freeze, or photo-ablate?: comparative symptom profile in Barrett's dysplasia patients undergoing endoscopic ablation

    Gill, Kanwar Rupinder S.; Gross, Seth A.; Greenwald, Bruce D.; Hemminger, Lois L.; Wolfsen, Herbert C.


    Background: There are few data available comparing endoscopic ablation methods for Barrett's esophagus with high-grade dysplasia (BE-HGD). Objective: To determine differences in symptoms and complications associated with endoscopic ablation. Design: Prospective observational study. Setting: Two tertiary care centers in USA. Patients: Consecutive patients with BE-HGD Interventions: In this pilot study, symptoms profile data were collected for BE-HGD patients among 3 endoscopic ablation methods: porfimer sodium photodynamic therapy, radiofrequency ablation and low-pressure liquid nitrogen spray cryotherapy. Main Outcome Measurements: Symptom profiles and complications from the procedures were assessed 1-8 weeks after treatment. Results: Ten BE-HGD patients were treated with each ablation modality (30 patients total; 25 men, median age: 69 years (range 53-81). All procedures were performed in the clinic setting and none required subsequent hospitalization. The most common symptoms among all therapies were chest pain, dysphagia and odynophagia. More patients (n=8) in the porfimer sodium photodynamic therapy group reported weight loss compared to radio-frequency ablactation (n=2) and cryotherapy (n=0). Four patients in the porfimer sodium photodynamic therapy group developed phototoxicity requiring medical treatment. Strictures, each requiring a single dilation, were found in radiofrequency ablactation (n=1) and porfimer sodium photodynamic therapy (n=2) patients. Limitations: Small sample size, non-randomized study. Conclusions: These three endoscopic therapies are associated with different types and severity of post-ablation symptoms and complications.

  8. Drinking and displacement: a systematic review of the influence of forced displacement on harmful alcohol use.

    Weaver, Heather; Roberts, Bayard


    This paper systematically reviews evidence about factors associated with harmful alcohol use amongst forcibly displaced persons, including refugees and internally displaced persons. Bibliographic and humanitarian-related databases were searched. The number of quantitative and qualitative studies that were screened and reviewed was 1108. Only 10 studies met inclusion criteria. Risk factors identified included gender, age, exposure to traumatic events and resulting posttraumatic stress disorder, prior alcohol consumption-related problems, year of immigration, location of residence, social relations, and postmigration trauma and stress. The evidence base was extremely weak, and there is a need to improve the quantity and quality of research about harmful alcohol use by forcibly displaced persons.

  9. Utilization of an ultrasound beam steering angle for measurements of tissue displacement vector and lateral displacement

    Chikayoshi Sumi


    Full Text Available Chikayoshi SumiDepartment of Information and Communication Sciences, Faculty of Science and Technology, Sophia University, Tokyo, JapanAbstract: A number of ultrasonic displacement/velocity measurement methods have been extensively developed for measurements of blood flow, tissue motion, and strain. Lateral modulation (LM methods have also been reported using steered, crossed beams, and these methods permit measurements of displacement vectors. In this report, a new beam steering method for the transmission and reception of ultrasound is proposed, which can enable measurements of lateral displacements and of arbitrary displacement vectors with a very high degree of accuracy. Because this beam steering method uses only a steering angle, this method is referred to as ASTA. With ASTA, the number of available methods to obtain a displacement vector measurement is limited to previously developed block-matching methods, such as the multidimensional cross-spectrum phase gradient method, and the multidimensional autocorrelation method (MAM and the multidimensional Doppler method (MDM using a block-matching method (the methods using block matching are referred to as MAMb and MDMb, respectively. Being dependent on the measurement method, only a lateral displacement measurement can be made even if the methods are multidimensional, ie, previously developed MAM and MDM using a moving average and a mirror setting of the obtained steered beams, and one-dimensional (1D, such as an autocorrelation method. Considerations of beamforming schemes using LM and ASTA show that the simple ASTA beamforming method increases capabilities for real-time measurements and requires a small physical aperture when compared with LM. For lateral displacement measurements (eg, blood flow in a carotid artery, a lateral coordinate must correspond to the direction of the target’s lateral motion, and the steering angle used is as large as possible to increase the measurement accuracy

  10. Electrolytic Effects During Tissue Ablation by Electroporation.

    Rubinsky, Liel; Guenther, Enric; Mikus, Paul; Stehling, Michael; Rubinsky, Boris


    Nonthermal irreversible electroporation is a new tissue ablation technique that consists of applying pulsed electric fields across cells to induce cell death by creating permanent defects in the cell membrane. Nonthermal irreversible electroporation is of interest because it allows treatment near sensitive tissue structures such as blood vessels and nerves. Two recent articles report that electrolytic reaction products at electrodes can be combined with electroporation pulses to augment and optimize tissue ablation. Those articles triggered a concern that the results of earlier studies on nonthermal irreversible electroporation may have been tainted by unaccounted for electrolytic effects. The goal of this study was to reexamine previous studies on nonthermal irreversible electroporation in the context of these articles. The study shows that the results from some of the earlier studies on nonthermal irreversible electroporation were affected by unaccounted for electrolysis, in particular the research with cells in cuvettes. It also shows that tissue ablation ascribed in the past to irreversible electroporation is actually caused by at least 3 different cytotoxic effects: irreversible electroporation without electrolysis, irreversible electroporation combined with electrolysis, and reversible electroporation combined with electrolysis. These different mechanisms may affect cell and tissue ablation in different ways, and the effects may depend on various clinical parameters such as the polarity of the electrodes, the charge delivered (voltage, number, and length of pulses), and the distance of the target tissue from the electrodes. Current clinical protocols employ ever-increasing numbers of electroporation pulses to values that are now an order of magnitude larger than those used in our first fundamental nonthermal irreversible electroporation studies in tissues. The different mechanisms of cell death, and the effect of the clinical parameters on the mechanisms may

  11. Silicon-Class Ablators for NIC Ignition Capsules

    Ho, Darwin; Salmonson, Jay; Haan, Steve


    We present design studies using silicon-class ablators (i.e., Si, SiC, SiB6, and SiB14) for NIC ignition capsules. These types of ablators have several advantages in that they: (a) require no internal dopant layers and are robust to M-band radiation; (b) have smooth outer surfaces; (c) have stable fuel-ablator interface; and (d) have good 1-D performance. The major disadvantage for some of the ablators in this class is the relatively smaller ablation stabilization. Consequently, the ablator is more susceptible to breakup caused by RT instabilities. However, smoother outer surfaces on this class of ablators can reduce the effect of RT instabilities. 2-D simulations of SiC ablators show ignition failure despite smooth surfaces and good 1-D performance. But SiB6 and SiB14 ablators exhibit promising behaviors. SiB6 (SiB14) ablators have high 1-D ignition margin and high peak core hydrodynamic pressure 880 (900) Gbar. The ablation scale length for SiB6 is longer than that for SiC and for SiB14 is comparable to that of plastic. Therefore, we expect acceptable performance for SiB6 and less RT growth for SiB14. 2-D simulations are now in progress.

  12. Wavelength dependence of soft tissue ablation by using pulsed lasers

    Xianzeng Zhang; Shusen Xie; Qing Ye; Zhenlin Zhan


    Pulsed laser ablation of soft biological tissue was studied at 10.6-, 2.94-, and 2.08-μm wavelengths. The ablation effects were assessed by means of optical microscope, the ablation crater depths were measured with reading microscope. It was shown that Er:YAG laser produced the highest quality ablation with clear,sharp cuts following closely the patial contour of the incident beam and the lowest fluence threshold. The pulsed CO2 laser presented the moderate quality ablation with the highest ablation efficiency. The craters drilled with Ho:YAG laser were generally larger than the incident laser beam spot, irregular in shape, and clearly dependent on the local morphology of biotissue. The blation characteristics, including fluence threshold and ablation efficiency, varied substantially with wavelength. It is not evident that water is the only dominant chromophore in tissue.

  13. Ablation of GaN Using a Femtosecond Laser

    刘伟民; 朱荣毅; 钱土雄; 袁述; 张国义


    We study the pulsed laser ablation of wurtzite gallium nitride (GaN) films grown on sapphire, using the fem tosecond laser beam at a central wavelength of 800nm as the source for the high-speed ablation of GaN films. By measuring the backscattered Raman spectrum of ablated samples, the dependence of the ablation depth on laser fluence with one pulse was obtained. The threshold laser fluence for the ablation of GaN films was determined to be about 0.25J/cm2. Laser ablation depth increases with the increasing laser fluence until the amount of removed material is not further increased. The ablated surface was investigated by an optical surface interference profile meter.

  14. Adjustment to trauma exposure in refugee, displaced, and non-displaced Bosnian women.

    Schmidt, Martina; Kravic, Nera; Ehlert, Ulrike


    The war in Bosnia resulted in the displacement of millions of civilians, most of them women. Ten years after the civil war, many of them are still living as refugees in their country of origin or abroad. Research on different refugee groups has continuously reported persistent levels of posttraumatic stress disorder (PTSD) and other mental-health problems in this population. The present study compared PTSD and self-concept in Bosnian refugee women (n = 29) with women who were internally displaced (IDP; n = 26) and non-displaced women (n = 32). Data were collected using the Bosnian Trauma Questionnaire and four scales assessing self-esteem, perceived incompetence, externality of control attribution, and persistence. IDPs scored significantly higher on PTSD symptoms, externality of control attribution and perceived incompetence, and lower on self-esteem than both refugee and non-displaced women. The level of education most strongly predicted PTSD symptom severity, followed by the type of displacement, and exposure to violence during the war. Associations of self-concept with displacement and psychopathology were inconsistent, with type of displacement predicting control attributions but not other aspects of self-concept and PTSD symptoms being partly related to perceived incompetence and self-esteem. These results support previous findings stating that, in the long run, refugees show better mental health than IDPs, and that witnessing violence is a traumatic experience strongly linked to the development of PTSD symptoms. Results further indicate that education plays an important role in the development of PTSD symptoms. Associations of control attributions and type of displacement were found; these results have not been previously documented in literature.

  15. Charge-displacement analysis for excited states

    Ronca, Enrico, E-mail:; Tarantelli, Francesco, E-mail: [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy); Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, via Elce di Sotto 8, I-06123 Perugia (Italy); Pastore, Mariachiara, E-mail:; Belpassi, Leonardo; De Angelis, Filippo [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy); Angeli, Celestino; Cimiraglia, Renzo [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, via Borsari 46, I-44100 Ferrara (Italy)


    We extend the Charge-Displacement (CD) analysis, already successfully employed to describe the nature of intermolecular interactions [L. Belpassi et al., J. Am. Chem. Soc. 132, 13046 (2010)] and various types of controversial chemical bonds [L. Belpassi et al., J. Am. Chem. Soc. 130, 1048 (2008); N. Salvi et al., Chem. Eur. J. 16, 7231 (2010)], to study the charge fluxes accompanying electron excitations, and in particular the all-important charge-transfer (CT) phenomena. We demonstrate the usefulness of the new approach through applications to exemplary excitations in a series of molecules, encompassing various typical situations from valence, to Rydberg, to CT excitations. The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.

  16. Wirelessly Interrogated Position or Displacement Sensors

    Woodard, Stanley E.; Taylor, Bryant D.


    Two simple position or displacement sensors based on inductance-capacitance resonant circuits have been conceived. These sensors are both powered and interrogated without use of wires and without making contact with other objects. Instead, excitation and interrogation are accomplished by means of a magnetic-field-response recorder. Both of the present position or displacement sensors consist essentially of variable rectangular parallel-plate capacitors electrically connected in series with fixed inductors. Simple inductance-capacitance circuits of the type used in these sensors are inherently robust; their basic mode of operation does not depend on maintenance of specific environmental conditions. Hence, these sensors can be used under such harsh conditions as cryogenic temperatures, high pressures, and radioactivity.

  17. Precision optical displacement measurements using biphotons

    Lyons, Kevin; Kwiat, Paul G; Jordan, Andrew N


    We propose and examine the use of biphoton pairs, such as those created in parametric down conversion or four-wave mixing, to enhance the precision and the resolution of measuring optical displacements by position-sensitive detection. We show that the precision of measuring a small optical beam displacement with this method can be significantly enhanced by the correlation between the two photons, given the same optical mode. The improvement is largest if the correlations between the photons are strong, and falls off as the biphoton correlation weakens. More surprisingly, we find that the smallest resolvable parameter of a simple split detector scales as the inverse of the number of biphotons for small biphoton number ("Heisenberg scaling"), because the Fisher information diverges as the parameter to be estimated decreases in value. One usually sees this scaling only for systems with many entangled degrees of freedom. We discuss the transition for the split-detection scheme to the standard quantum limit scalin...

  18. Comparing anisotropic displacement parameters in protein structures.

    Merritt, E A


    The increasingly widespread use of synchrotron-radiation sources and cryo-preparation of samples in macromolecular crystallography has led to a dramatic increase in the number of macromolecular structures determined at atomic or near-atomic resolution. This permits expansion of the structural model to include anisotropic displacement parameters U(ij) for individual atoms. In order to explore the physical significance of these parameters in protein structures, it is useful to be able to compare quantitatively the electron-density distribution described by the refined U(ij) values associated with corresponding crystallographically independent atoms. This paper presents the derivation of an easily calculated correlation coefficient in real space between two atoms modeled with anisotropic displacement parameters. This measure is used to investigate the degree of similarity between chemically equivalent but crystallographically independent atoms in the set of protein structural models currently available from the Protein Data Bank.

  19. Determining fault geometries from surface displacements

    Volkov, D.; Voisin, C.; Ionescu, I. R.


    We study in this paper a half space linear elasticity model for surface displacements caused by slip along underground faults. We prove uniqueness of the fault location and (piecewise planar) geometry and of the slip field for a given surface displacement field.We then introduce a reconstruction algorithm for the realistic case where only a finite number of surface measurements are available.After showing how this algorithm performs on simulated data and assessing the effect of noise, we apply it to measured data. The data was recorded during slow slip events in Guerrero, Mexico. Since this is a well studied subduction zone, it is possible to compareour inferred fault geometry to other reconstructions (obtained using different techniques), found in the literature.

  20. Air displacement plethysmography: cradle to grave.

    Fields, David A; Gunatilake, Ravindu; Kalaitzoglou, Evangelia


    Differences in body composition are associated with increased disease risk in various stages of life. Despite numerous available methods in assessing body composition (air displacement plethysmography, dual-energy X-ray absorptiometry, bioelectrical impedance, hydrometry, and magnetic resonance imaging), due to innate technical limitations, the ability for one singular method to track body composition over the life span (ie, infancy to adulthood) is challenging and imperfect. The primary goal of this review is to determine if there are body composition methods that can accurately track body composition from infancy into adulthood. After careful consideration and taking into account the best available scientific evidence, we feel air displacement plethysmography is the best instrument at this time for tracking body composition, starting in infancy and forward into adulthood, partly because it is the only "practical" clinical tool currently available for use during infancy. © 2015 American Society for Parenteral and Enteral Nutrition.

  1. Personal Exposure in Displacement Ventilated Rooms

    Brohus, Henrik; Nielsen, Peter Vilhelm


    Personal exposure in a displacement ventilated room is examined. The stratified flow and the considerable concentration gradients necessitate an improvement of the widely used fully mixing compartmental approach. The exposure of a seated and a standing person in proportion to the stratification...... height is examined by means of full-scale measurements. A breathing thermal manikin is used to simulate a person. It is found that the flow in the boundary layer around a person is able to a great extent to entrain and transport air from below the breathing zone. In the case of non-passive, heated...... in the lower part of the room close to the occupant. A personal exposure model for displacement ventilated rooms is proposed. The model takes the influence of gradients and the human thermal boundary layer into account. Two new quantities describing the interaction between a person and the ventilation...

  2. Cooling airflow design tool for displacement ventilation.

    Schiavon, Stefano; Bauman, Fred


    These user notes describe how to use a spreadsheet-based (Excel 2007) version of the ASHRAE method (Chen and Glicksman 2003) for calculating the amount of design cooling airflow required for a displacement ventilation (DV) system that is providing all sensible cooling for a conditioned space. The design tool has been developed by CBE and is available on the CBE Partner website:

  3. Experiments on chemically enhanced immiscible fluid displacements

    Soori, Tejaswi; Ward, Thomas


    This talk focuses on experiments conducted by displacing a vegetable oil within a capillary tube (diameter forms a stable micro-emulsion. We estimate the shear viscosity of the emulsion as a function of alkali and aqueous/oil concentrations. Separately we attempt to measure the average bulk diffusion coefficient of the emulsion in both phases which is necessary to estimate the Péclet number (Pé) and subsequent mass transport phenomena. American Chemical Society Petroleum Research Fund.

  4. Intrinsic Mean Square Displacements in Proteins

    VURAL, Derya; Glyde, Henry R.


    The thermal mean square displacement (MSD) of hydrogen in proteins and its associated hydration water is measured by neutron scattering experiments and used an indicator of protein function. The observed MSD as currently determined depends on the energy resolution width of the neutron scattering instrument employed. We propose a method for obtaining the intrinsic MSD of H in the proteins, one that is independent of the instrument resolution width. The intrinsic MSD is defined as the infinite ...

  5. Digital image correlation: displacement accuracy estimation

    Wattrisse B.


    Full Text Available The aim of this collaborative work is to study the uncertainties associated with Digital Image Correlation techniques (DIC. More specifically, the link between displacement uncertainties and several correlation parameters chosen by the user and relative to the image analysis software and several image characteristics like speckle size and image noise is emphasized. A previous work [1] has been done for situations with spatially fluctuating displacement fields which dealt with mismatch error linked to the discrepancy between the adopted shape function and the real displacement field in the subset. This present work is focused on the ultimate error regime. To ensure that there is no mismatch error, synthetic images of plane rigid body translation have been analysed. DIC softwares developed by or used in the French community were used to study a large number of settings. The first observations are: (a bias amplitude is almost always insensitive to the subset size, (b DIC formulations can be split up into two families. For the first one, the bias amplitude increases with the noise while it remains constant for the second one. For both families, the mean value of the random error increases with the noise level and with the inverse of the subset size. Furthermore, the random error decreases with the radius of the speckle for the first family, while it increases for the second one. These two different behaviours of the tested DIC package are probably due to their underlying DIC formulation (interpolation, correlation criteria, optimisation process.

  6. Automating Recession Curve Displacement Recharge Estimation.

    Smith, Brennan; Schwartz, Stuart


    Recharge estimation is an important and challenging element of groundwater management and resource sustainability. Many recharge estimation methods have been developed with varying data requirements, applicable to different spatial and temporal scales. The variability and inherent uncertainty in recharge estimation motivates the recommended use of multiple methods to estimate and bound regional recharge estimates. Despite the inherent limitations of using daily gauged streamflow, recession curve displacement methods provide a convenient first-order estimate as part of a multimethod hierarchical approach to estimate watershed-scale annual recharge. The implementation of recession curve displacement recharge estimation in the United States Geologic Survey (USGS) RORA program relies on the subjective, operator-specific selection of baseflow recession events to estimate a gauge-specific recession index. This paper presents a parametric algorithm that objectively automates this tedious, subjective process, parameterizing and automating the implementation of recession curve displacement. Results using the algorithm reproduce regional estimates of groundwater recharge from the USGS Appalachian Valley and Piedmont Regional Aquifer-System Analysis, with an average absolute error of less than 2%. The algorithm facilitates consistent, completely automated estimation of annual recharge that complements more rigorous data-intensive techniques for recharge estimation. © 2016, National Ground Water Association.

  7. A reference material for dynamic displacement calibration

    Davighi, A.; Hack, E.; Patterson, E.; Whelan, M.


    Calibration of displacement and strain measurement systems is an essential step in providing traceability and confidence in stress and strain distributions obtained from experiment and used to validate simulations employed in engineering design. Reference materials provide a simple, well-defined distribution of the measured quantity that can be traced to an international standard and can be used to assess the uncertainty associated with the measurement system. Previous work has established a reference material and procedure for calibrating optical systems for measuring static, in-plane strain distributions and also demonstrated its use. A new effort is in progress to extend this work to the measurement of three-dimensional displacement distributions induced by cyclic and dynamic loading, including transients and large-scale deformation. The first step in this effort has been to define both the essential and desirable attributes of a reference material for calibrating systems capable of measurements of dynamic displacement and strain. An international consortium of research laboratories, system designers, manufacturers and end-users has identified a list of attributes and members of the experimental mechanics community have been asked to weight the importance of these attributes. The attributes are being utilised to evaluate candidate designs for the reference material which have been generated through a series of brain-storming sessions within the consortium.

  8. Comparing Teaching Approaches About Maxwell's Displacement Current

    Karam, Ricardo; Coimbra, Debora; Pietrocola, Maurício


    Due to its fundamental role for the consolidation of Maxwell's equations, the displacement current is one of the most important topics of any introductory course on electromagnetism. Moreover, this episode is widely used by historians and philosophers of science as a case study to investigate several issues (e.g. the theory-experiment relationship). Despite the consensus among physics educators concerning the relevance of the topic, there are many possible ways to interpret and justify the need for the displacement current term. With the goal of understanding the didactical transposition of this topic more deeply, we investigate three of its domains: (1) The historical development of Maxwell's reasoning; (2) Different approaches to justify the term insertion in physics textbooks; and (3) Four lectures devoted to introduce the topic in undergraduate level given by four different professors. By reflecting on the differences between these three domains, significant evidence for the knowledge transformation caused by the didactization of this episode is provided. The main purpose of this comparative analysis is to assist physics educators in developing an epistemological surveillance regarding the teaching and learning of the displacement current.

  9. International Monetary Fund and aid displacement.

    Stuckler, David; Basu, Sanjay; McKee, Martin


    Several recent papers find evidence that global health aid is being diverted to reserves, education, military, or other sectors, and is displacing government spending. This is suggested to occur because ministers of finance have competing, possibly corrupt, priorities and deprive the health sector of resources. Studies have found that development assistance for health routed to governments has a negative impact on health spending and that similar assistance routed to private nongovernmental organizations has a positive impact. An alternative hypothesis is that World Bank and IMF macro-economic policies, which specifically advise governments to divert aid to reserves to cope with aid volatility and keep government spending low, could be causing the displacement of health aid. This article evaluates whether aid displacement was greater when countries undertook a new borrowing program from the IMF between 1996 and 2006. As found in existing studies, for each $1 of development assistance for health, about $0.37 is added to the health system. However, evaluating IMF-borrowing versus non-IMF-borrowing countries reveals that non-borrowers add about $0.45 whereas borrowers add less than $0.01 to the health system. On average, health system spending grew at about half the speed when countries were exposed to the IMF than when they were not. It is important to take account of the political economy of global health finance when interpreting data on financial flows.

  10. Ablation of steel using picosecond laser pulses in burst mode

    Lickschat, Peter; Demba, Alexander; Weissmantel, Steffen


    Results obtained in picosecond laser processing of steel applying the burst mode are presented. Using the burst mode, pulse trains, i.e., bursts, consisting of a number of picosecond pulses with an inter-pulse delay of 12.5 ns and 10 ps pulse duration are applied for material processing. Small cavities with sizes in the range of the laser beam diameter made by single-burst ablation are compared to quadratic cavities of 0.5 × 0.5 mm² produced by multiburst ablation and simultaneous scanning of the laser beam across the steel sample surface. The ablated volume per pulse within the burst was calculated either from the ablated volume per burst or from the ablation depth of the quadratic cavities. With the second to fourth pulses in the bursts, a reduction of the ablated volume per pulse in comparison with the first pulse in the bursts (i.e., to the use of single pulses) was found for both single- and multiburst ablation, which is assumed to be due to plasma shielding. By contrast, the ablated volume per pulse within the bursts increases for the fifth to eighth pulses. Heat accumulation effect and the influence of the heated plasma can be assumed to be the reason for these higher ablation rates. SEM micrographs also show that there is a higher melt ejection out of the laser processed area. This is indicated by the formation of bulges about the ablated area.

  11. Percutaneous thermal ablation of renal neoplasms; Perkutane Thermoablation von Nierentumoren

    Tacke, J. [Inst. fuer Diagnostische und Interventionelle Radiologie/Neuroradiologie, Klinikum Passau (Germany); Mahnken, A.H.; Guenther, R.W. [Klinik fuer Radiologische Diagnostik, Universitaetsklinikum Aachen (Germany)


    Due to modern examination techniques such as multidetector computed tomography and high-field magnetic resonance imaging, the detection rate of renal neoplasms is continually increasing. Even though tumors exceeding 4 cm in diameter rarely metastasize, all renal lesions that are possible neoplasms should be treated. Traditional treatment techniques include radical nephrectomy or nephron-sparing resection, which are increasingly performed laparoscopically. Modern thermal ablation techniques such as hyperthermal techniques like radiofrequency ablation RFA, laser induced thermal ablation LITT, focused ultrasound FUS and microwave therapy MW, as well as hypothermal techniques (cryotherapy) may be a useful treatment option for patients who are unfit for or refuse surgical resection. Cryotherapy is the oldest and best known thermal ablation technique and can be performed laparoscopically or percutaneously. Since subzero temperatures have no antistyptic effect, additional maneuvers must be performed to control bleeding. Percutaneous cryotherapy of renal tumors is a new and interesting method, but experience with it is still limited. Radiofrequency ablation is the most frequently used method. Modern probe design allows volumes between 2 and 5 cm in diameter to be ablated. Due to hyperthermal tract ablation, the procedure is deemed to be safe and has a low complication rate. Although there are no randomized comparative studies to open resection, the preliminary results for renal RFA are promising and show RFA to be superior to other thermal ablation techniques. Clinical success rates are over 90% for both, cryo- and radiofrequency ablation. Whereas laser induced thermal therapy is established in hepatic ablation, experience is minimal with respect to renal application. For lesions of more than 2 cm in diameter, additional cooling catheters are required. MR thermometry offers temperature control during ablation. Microwave ablation is characterized by small ablation volumes

  12. 3D Multifunctional Ablative Thermal Protection System

    Feldman, Jay; Venkatapathy, Ethiraj; Wilkinson, Curt; Mercer, Ken


    NASA is developing the Orion spacecraft to carry astronauts farther into the solar system than ever before, with human exploration of Mars as its ultimate goal. One of the technologies required to enable this advanced, Apollo-shaped capsule is a 3-dimensional quartz fiber composite for the vehicle's compression pad. During its mission, the compression pad serves first as a structural component and later as an ablative heat shield, partially consumed on Earth re-entry. This presentation will summarize the development of a new 3D quartz cyanate ester composite material, 3-Dimensional Multifunctional Ablative Thermal Protection System (3D-MAT), designed to meet the mission requirements for the Orion compression pad. Manufacturing development, aerothermal (arc-jet) testing, structural performance, and the overall status of material development for the 2018 EM-1 flight test will be discussed.

  13. [Atrial fibrillation ablation: application of nurse methodology].

    Ramos-González-Serna, Amelia; Mateos-García, M Dolores


    Ablation of pulmonary veins for treatment of atrial fibrillation involves applying radiofrequency energy wave by a catheter that causes a circumferential lesion to achieve electrical isolation and voltage drop in the interior. It is mainly applied when there is resistance to treatment and recurrence of symptoms affecting the quality of life of patients. The nurse is an important part of the multidisciplinary team who care for patients who undergo this procedure. The provision of comprehensive nursing care should include nursing procedures prior to, during, and after treatment to ensure the careful and systematic quality required. The aims of this article are: to provide specialised knowledge on the procedure of atrial fibrillation ablation, to describe the preparation of the electrophysiology laboratory, analyse nursing care and develop a standardized care plan for patients on whom this procedure is performed using the NANDA (North American Nursing Association) taxonomy and NIC (Nursing Intervention Classification).

  14. Ultrasonography for non-displaced and mini-displaced humeral lateral condyle fractures in children

    ZHANG Jing-dong; CHEN Hua


    Objective: To evaluate the value of ultrasonography in non-displaced and mini-displaced humeral lateral condyle fractures in children.Methods: Nine children aged 2-9 years with non-displaced or mini-displaced humeral lateral condyle fractures were examined by high-resolution ultrasonography.The fracture line through the joint surface was visualized by ultrasonography in 6 case,in which closed reduction and percutaneous pinning was performed on 3 patients and other 3 patients did not receive the treatment because of patients' or their parents'refusal.In the remaining 3 children,ultrasonography did not reveal the cartilaginous trochle involvement at the joint surface and conservative treatment was adopted.Results: The average follow-up period was 8 months.The sonographic findings were confirmed by magnetic resonance imaging in one child who received conservative treatment and another child who received percutaneous pinning.The elbow function and fractttre healing were good in cases received closed reduction and percutaneous pinning.Among the three cases who refused to receive closed reduction and internal f'txation,re-displacement occurred in 1 case and delayed union in 1 case.All three cases receiving conservative treatment had good results both in elbow function and fracture healing.Conclusion: High-resolution ultrasonography enable to reveal non-displaced and mini-displaced humeral lateral condyle fractures as well as to ascertain whether the cartilaginous trochlea humeri was involved.For these cases,arthrography or magnetic resonance imaging is unnecessary.

  15. Design calculations for NIF convergent ablator experiments

    Olson R.E.


    Full Text Available The NIF convergent ablation tuning effort is underway. In the early experiments, we have discovered that the design code simulations over-predict the capsule implosion velocity and shock flash ρr, but under-predict the hohlraum x-ray flux measurements. The apparent inconsistency between the x-ray flux and radiography data implies that there are important unexplained aspects of the hohlraum and/or capsule behavior.

  16. Radiofrequency ablation of two femoral head chondroblastomas

    Petsas, Theodore [Department of Radiology, University of Patras (Greece); Megas, Panagiotis [Department of Orthopaedic Surgery, University of Patras (Greece)]. E-mail:; Papathanassiou, Zafiria [Department of Radiology, University of Patras (Greece)


    Chondroblastoma is a rare benign cartilaginous bone tumor. Surgical resection is the treatment of choice for pain relief and prevention of further growth. Open surgical techniques are associated with complications, particularly when the tumors are located in deep anatomical sites. The authors performed RF ablation in two cases of subarticular femoral head chondroblastomas and emphasize its positive impact. The clinical course, the radiological findings and the post treatment results are discussed.

  17. Design calculations for NIF convergent ablator experiments

    Olson R.E.; Hicks D.G.; Meezan N.B.; Callahan D.A.; Landen O.L.; Jones O.S.; Langer S.H.; Kline J.L.; Wilson D.C.; Rinderknecht H.; Zylstra A.; Petrasso R.D.


    The NIF convergent ablation tuning effort is underway. In the early experiments, we have discovered that the design code simulations over-predict the capsule implosion velocity and shock flash ρr, but under-predict the hohlraum x-ray flux measurements. The apparent inconsistency between the x-ray flux and radiography data implies that there are important unexplained aspects of the hohlraum and/or capsule behavior.

  18. Investigating Age Resolution in Laser Ablation Geochronology

    Horstwood, Matt; Kosler, Jan; Jackson, Simon; Pearson, Norman; Sylvester, Paul


    Workshop on Data Handling in LA-ICP-MS U-Th-Pb Geochronology; Vancouver, British Columbia, Canada, 12-13 July 2008; Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) uranium-thorium-lead (U-Th-Pb) dating is an increasingly popular approach for determining the age of mineral grains and the timing of geological events. The spatial resolution offered by this technique allows detailed investigations of complex igneous and metamorphic processes, and the speed of data capture allows vast amounts of information to be gathered rapidly. Laser ablation U-Th-Pb dating is therefore becoming an increasingly influential technique to the geochronology community, providing cost-effective and ready access to age data for laboratories and end users worldwide. However, complications in acquiring, processing, and interpreting data can lead to inaccurate age information entering the literature. With the numbers of practitioners expanding rapidly, the need to standardize approaches and resolve difficulties (particularly involving the subjectivity in processing laser ablation U-Th-Pb data) is becoming important.

  19. Microwave soft tissue ablation (Invited Paper)

    Clegg, Peter J.; Cronin, Nigel J.


    Microsulis, in conjunction with the University of Bath have developed a set of novel microwave applicators for the ablation of soft tissues. These interstitial applicators have been designed for use in open surgical, laparoscopic and percutaneous settings and range in diameter from 2.4 to 7 mm. A 20 mm diameter flat faced interface applicator was developed as an adjunct to the open surgical interstitial applicator and has been applied to the treatment of surface breaking lesions in hepatobiliary surgery. Taken as a complete tool set the applicators are capable of treating a wide range of conditions in a safe and efficacious manner. The modality employs a radiated electromagnetic field at the allocated medical frequency of 2.45 GHz and powers between 30 and 150 Watts. Computer simulations, bench testing, safety and efficacy testing, ex-vivo and in-vivo work plus clinical trials have demonstrated that these systems are capable of generating large volumes of ablation in short times with favourable ablation geometries. Clinical studies have shown very low complication rates with minimal local recurrence. It is considered that this modality offers major advantages over currently marketed products. The technique is considered to be particularly safe as it is quick and there is no passage of current obviating the requirement for grounding pads. Since the microwave field operates primarily on water and all soft tissues with the exception of fat are made up of approximately 70% water the heating pattern is highly predictable making repeatability a key factor for this modality.

  20. Laser ablation cell sorting in scanning cytometry

    Shen, Feimo; Price, Jeffrey H.


    Flow cytometry has been an important tool for automated cells sorting. However, the lack of good sensitivity prevents it from being used for rare events sorting; furthermore, fragile cells, anchorage-dependent cells, and clump forming cells cannot be sorted this way. A fully automated, high-speed scanning cytometer with autofocus and image segmentation is capable of accurately locating contaminant cells in a monolayer cell population. A laser ablation system was incorporated into the cytometer to negatively sort out the unwanted cells by applying a focused, ultra-short laser pulse (sub-micron diameter, pulse duration = 4 nsec, wavelength - 500 nm) to each targeted cell. Due to the high power density (approximately 1010 W/cm2) that was present at the focal point, disruptive mechanical forces were generated and were responsible for the kill. Fluorescently stained NIH-3T3 fibroblast cells were used as a model contaminant target ells in an unstained NIH-3T3 population to determine the identification-kill effectiveness. The contaminant cells were stained with the fluorochrome CellTracker Blue CMAC, whereas the background cells were left intact. Ablation pulses were applied in frame-by-frame increment batches to the cell culture on the microscope. The negative sorting effectiveness was analyzed by automatically re-scanning the post-ablation cell culture in phase contrast and propidium iodide stained epi fluorescent fields to verify cell death.

  1. Ultraviolet laser ablation of polyimide films

    Srinivasan, R.; Braren, B.; Dreyfus, R. W.


    Pulsed laser radiation at 193, 248, or 308 nm can etch films of polyimide (DuPont KaptonTM). The mechanism of this process has been examined by the chemical analysis of the condensible products, by laser-induced fluorescence analysis of the diatomic products, and by the measurement of the etch depth per pulse over a range of fluences of the laser pulse. The most important product as well as the only one condensible at room temperature is carbon. Laser-induced fluorescence analysis showed that C2 and CN were present in the ablation plume. At 248 nm, even well below the fluence threshold of 0.08 J/cm2 for significant ablation, these diatomic species are readily detected and are measured to leave the polymer surface with translational energy of ˜5 eV. These results, when combined with the photoacoustic studies of Dyer and Srinivasan [Appl. Phys. Lett. 48, 445 (1986)], show that a simple photochemical mechanism in which one photon or less (on average) is absorbed per monomer is inadequate. The ablation process must involve many photons per monomer unit to account for the production of predominantly small (<4 atoms) products and the ejection of these fragments at supersonic velocities.

  2. Radiative Ablation of Disks Around Massive Stars

    Kee, N D


    Hot, massive stars (spectral types O and B) have extreme luminosities ($10^4 -10^6 L_\\odot$) that drive strong stellar winds through UV line-scattering. Some massive stars also have disks, formed by either decretion from the star (as in the rapidly rotating "Classical Be stars"), or accretion during the star's formation. This dissertation examines the role of stellar radiation in driving (ablating) material away from these circumstellar disks. A key result is that the observed month to year decay of Classical Be disks can be explained by line-driven ablation without, as previously done, appealing to anomalously strong viscous diffusion. Moreover, the higher luminosity of O stars leads to ablation of optically thin disks on dynamical timescales of order a day, providing a natural explanation for the lack of observed Oe stars. In addition to the destruction of Be disks, this dissertation also introduces a model for their formation by coupling observationally inferred non-radial pulsation modes and rapid stellar...

  3. A tubular electrode for radiofrequency ablation therapy

    Antunes, Carlos Lemos Lemos Lemos


    Purpose – Due to its good mechanical and biocompatibility characteristics, nitinol SEMS is a popular endoprothesis used for relieving stricture problems in hollow organs due to carcinomas. Besides its mechanical application, SEMS can be regarded as well as potential electrode for performing RF ablation therapy on the tumor. The purpose of this work is to perform numerical and experimental analyses in order to characterize the lesion volume induced in biological tissue using this kind of tubular electrode. Design/methodology/approach – Data concerning electrical conductivity and dimension of the damaged tissue after RF ablation procedure were obtained from ex vivo samples. Next, numerical models using 3D finite element method were obtained reassembling the conditions considered at experimentation setup and results were compared. Findings – Numerical and experimental results show that a regular volume of damaged tissue can be obtained considering this type of electrode. Also, results obtained from numerical simulation are close to those obtained by experimentation. Originality/value – SEMSs, commonly used as devices to minimize obstruction problems due to the growth of tumors, may still be considered as an active electrode for RF ablation procedures. A method considering this observation is presented in this paper. Also, numerical simulation can be regarded in this case as a tool for determining the lesion volume.

  4. 7 CFR 1944.667 - Relocation and displacement.


    ... permanent or temporary relocation of displaced persons for units repaired or rehabilitated or for individual... displaced persons. The applicant shall include in its statement of activities, a statement concerning...

  5. HIV and the internally displaced: Burundi in focus

    Raquel Wexler


    Full Text Available "Special attention should also be given to the prevention of contagious and infectious diseases, including AIDS, among internally displaced persons." (Guiding Principles on InternalDisplacement, 19.3

  6. Displacement Mechanism of Polymer Flooding by Molecular Tribology

    YANG Er-Long; SONG Kao-Ping


    @@ Whether polymer flooding can enhance displacement efficiency or not is still a problem under debate. Laboratory experiment, numerical simulation and core data analysis are the commonly used means to study polymer flooding displacement efficiency.

  7. Is competition needed for ecological character displacement? Does displacement decrease competition?

    Abrams, Peter A; Cortez, Michael H


    Interspecific competition for resources is generally considered to be the selective force driving ecological character displacement, and displacement is assumed to reduce competition. Skeptics of the prevalence of character displacement often cite lack of evidence of competition. The present article uses a simple model to examine whether competition is needed for character displacement and whether displacement reduces competition. It treats systems with competing resources, and considers cases when only one consumer evolves. It quantifies competition using several different measures. The analysis shows that selection for divergence of consumers occurs regardless of the level of between-resource competition or whether the indirect interaction between the consumers is competition (-,-), mutualism (+,+), or contramensalism (+,-). Also, divergent evolution always decreases the equilibrium population size of the evolving consumer. Whether divergence of one consumer reduces or increases the impact of a subsequent perturbation of the other consumer depends on the parameters and the method chosen for measuring competition. Divergence in mutualistic interactions may reduce beneficial effects of subsequent increases in the other consumer's population. The evolutionary response is driven by an increase in the relative abundance of the resource the consumer catches more rapidly. Such an increase can occur under several types of interaction.

  8. Convergent ablation measurements of plastic ablators in gas-filled rugby hohlraums on OMEGA

    Casner, A.; Jalinaud, T.; Masse, L.; Galmiche, D.


    Indirect-drive implosions experiments were conducted on the Omega Laser Facility to test the performance of uniformly doped plastic ablators for Inertial Confinement Fusion. The first convergent ablation measurements in gas-filled rugby hohlraums are reported. Ignition relevant limb velocities in the range from 150 to 300 μm .n s-1 have been reached by varying the laser drive energy and the initial capsule aspect ratio. The measured capsule trajectory and implosion velocity are in good agreement with 2D integrated simulations and a zero-dimensional modeling of the implosions. We demonstrate experimentally the scaling law for the maximum implosion velocity predicted by the improved rocket model [Y. Saillard, Nucl. Fusion 46, 1017 (2006)] in the high-ablation regime case.

  9. Innovative techniques for image-guided ablation of benign thyroid nodules: Combined ethanol and radiofrequency ablation

    Park, Hye Sun; Baek, Jung Hwan; Choi, Young Jun; Lee, Jeong Hyun [Dept. of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of)


    In the treatment of benign thyroid nodules, ethanol ablation (EA), and radiofrequency ablation (RFA) have been suggested for cystic and solid thyroid nodules, respectively. Although combining these ablation techniques may be effective, no guidelines for or reviews of the combination have been published. Currently, there are three ways of combining EA and RFA: additional RFA is effective for treatment of incompletely resolved symptoms and solid residual portions of a thyroid nodule after EA. Additional EA can be performed for the residual unablated solid portion of a nodule after RFA if it is adjacent to critical structures (e.g., trachea, esophagus, and recurrent laryngeal nerve). In the concomitant procedure, ethanol is injected to control venous oozing after aspiration of cystic fluid prior to RFA of the remaining solid nodule.

  10. Transient Newton rings in dielectrics upon fs laser ablation

    Garcia-Lechuga, Mario; Hernandez-Rueda, Javier; Solis, Javier


    We report the appearance of transient Newton rings in dielectrics (sapphire and lead-oxide glass) during ablation with single fs laser pulses. Employing femtosecond microscopy with 800 nm excitation and 400 nm illumination, we observe a characteristic ring pattern that dynamically changes for increasing delay times between pump and probe pulse. Such transient Newton rings have been previously observed in metals and semiconductors at fluences above the ablation threshold and were related to optical interference of the probe beam reflected at the front surface of the ablating layer and at the interface of the non-ablating substrate. Yet, it had been generally assumed that this phenomenon cannot be (and has not been) observed in dielectrics due to the different ablation mechanism and optical properties of dielectrics. The fact that we are able to observe them has important consequences for the comprehension of the ablation mechanisms in dielectrics and provides a new method for investigating these mechanisms in ...

  11. Ablation Performance of a Novel Super-hybrid Composite

    Jun QIU; Xiaoming CAO; Chong TIAN; Jinsong ZHANG


    A novel super-hybrid composite (NSHC) was boron-modified phenolic resin (BPR) with three-dimensional reticulated SiC ceramic (3DRC) and high silica fibers. Ablation performance of the NSHC was studied. The results show that the linear ablation rate of NSHC was lower than that of pure BPR and the high silica/BPR composite. Its linear ablation rate is 1/17 of the high silica/BPR. Mass ablation rate of the NSHC is very close to that of the pure BPR and the high silica/BPR composite. Scanning electron microscope (SEM) analysis indicates that 3DRC has scarcely changed its shape at the ablation temperature. Its special reticulated structure can restrict the materials deformation and prevent high velocity heat flow from eroding the surface of the materials largely and thus increase ablation resistance of the NSHC.

  12. From Word to Image: Displacement and Meaning in "Greed."

    Grindon, Leger


    Describes levels of displacement in Stroheim's film "Greed," including (1) the displacement of reason, pleasure, and life by the desire for gold; and (2) the displacement that points to a double movement in Stroheim's cinematic style. Argues that the film's sense of doom arises from the psychic nightmare operating through the mechanics…

  13. 24 CFR 583.310 - Displacement, relocation, and acquisition.


    ... persons. A displaced person (defined in paragraph (f) of this section) must be provided relocation... “displaced person,” or the amount of relocation assistance for which the person is eligible, may file a... to the HUD field office. (f) Definition of displaced person. (1) For purposes of this section,...

  14. 24 CFR 886.138 - Displacement, relocation, and acquisition.


    ... regulations at 49 CFR part 24. A “displaced person” shall be advised of his or her rights under the Fair... person is ineligible under 49 CFR 24.2(g)(2); or (iv) HUD determines that the person was not displaced as... persons. A “displaced person” (as defined in paragraph (g) of this section) must be provided...

  15. Temperature insensitive measurements of displacement using fiber Bragg grating sensors

    Yang, Shuang; Li, Jun; Xu, Shengming; Sun, Miao; Tang, Yuquan; Gao, Gang; Dong, Fengzhong


    Optical fiber Bragg grating (FBG) displacement sensors play an important role in various areas due to the high sensitivity to displacement. However, it becomes a serious problem of FBG cross-sensitivity of temperature and displacement in applications with FBG displacement sensing. This paper presents a method of temperature insensitive measurement of displacement via using an appropriate layout of the sensor. A displacement sensor is constructed with two FBGs mounted on the opposite surface of a cantilever beam. The wavelengths of the FBGs shift with a horizontal direction displacement acting on the cantilever beam. Displacement measurement can be achieved by demodulating the wavelengths difference of the two FBGs. In this case, the difference of the two FBGs' wavelengths can be taken in order to compensate for the temperature effects. Four cantilever beams with different shapes are designed and the FBG strain distribution is quite different from each other. The deformation and strain distribution of cantilever beams are simulated by using finite element analysis, which is used to optimize the layout of the FBG displacement sensor. Experimental results show that an obvious increase in the sensitivity of this change on the displacement is obtained while temperature dependence greatly reduced. A change in the wavelength can be found with the increase of displacement from 0 to 10mm for a cantilever beam. The physical size of the FBG displacement sensor head can be adjusted to meet the need of different applications, such as structure health monitoring, smart material sensing, aerospace, etc.

  16. Rhetorics of Displacement: Constructing Identities in Forced Relocations

    Powell, Katrina M.


    Forced displacement has often involved the use of rhetoric, both by government institutions and by people who struggle not only to survive displacement, but also to resist it. In this article, the author offers first a theoretical framework that informs her thinking about displacement narratives. She briefly examines two published displacement…

  17. Year of displaced people’s rights in Colombia

    Marco Alberto Romero


    Full Text Available A Campaign for the Rights of Displaced People in Colombia, launched in 2007 by UNHCR, Colombian NGO CODHES and the Catholic Church, has tried to raise awareness in Colombia and the international community about the severity of the country’s displacement crisis and its failure to guarantee the rights of displaced people.

  18. Steerable sheath technology in the ablation of atrial fibrillation.

    Joseph, Jubin; Wong, Kelvin C K; Ginks, Matthew R; Bashir, Yaver; Betts, Timothy R; Rajappan, Kim


    Steerable sheaths have been shown to reduce procedure time in the catheter ablation of atrial fibrillation (AF), where catheter positioning and stability is typically challenging. This review critically addresses and highlights the recent developments in design of sheaths used to manipulate the ablation catheter and how these developments may impact on the ablation procedure itself, in particular the likelihood of first-time success. Patents relating to steerable sheaths are reviewed and discussed to gauge potential future developments in this area.

  19. The Theme of Displacement in Contemporary Art

    John POTTS


    Full Text Available Cet article examine les images et idées de dislocation dans des œuvres d'art récentes. Le thème du déplacement ou de la dislocation est traité dans le contexte de l'aspect globalisant de l'art contemporain, considéré lui-même comme un reflet de la mondialisation. Les principaux textes théoriques qui influencent et informent les pratiques en matière de conservation sont abordés, entre autres les écrits de Giorgio Agamben, Nicolas Bourriaud et Rex Butler. Le thème de la dislocation dans l'art contemporain est analysé au travers des œuvres de nombreux artistes, tels que Francis Alÿs, Bill Fontana, Allan Sekula, Chen Chieh-jen, Ai Wei Wei, Rosemary Laing, Mike Parr, Santiago Sierra, Rebecca Belmore et Tracey Moffatt.This essay considers images and ideas of displacement in recent works of art. The theme of displacement is examined in the context of the globalist aspect of contemporary art, itself a reflection of globalisation. Influential theoretical texts informing curatorial practice and the discourse of contemporary art theory are discussed, including the writings of Girogio Agamben, Nicolas Bourriaud and Rex Butler. The theme of displacement in contemporary art is analysed with regard to the work of many artists, including Francis Alÿs, Bill Fontana, Allan Sekula, Chen Chieh-jen, Ai Wei Wei, Rosemary Laing, Mike Parr, Santiago Sierra, Rebecca Belmore and Tracey Moffatt.

  20. Sample displacement chromatography of plasmid DNA isoforms.

    Černigoj, Urh; Martinuč, Urška; Cardoso, Sara; Sekirnik, Rok; Krajnc, Nika Lendero; Štrancar, Aleš


    Sample displacement chromatography (SDC) is a chromatographic technique that utilises different relative binding affinities of components in a sample mixture and has been widely studied in the context of peptide and protein purification. Here, we report a use of SDC to separate plasmid DNA (pDNA) isoforms under overloading conditions, where supercoiled (sc) isoform acts as a displacer of open circular (oc) or linear isoform. Since displacement is more efficient when mass transfer between stationary and mobile chromatographic phases is not limited by diffusion, we investigated convective interaction media (CIM) monoliths as stationary phases for pDNA isoform separation. CIM monoliths with different hydrophobicities and thus different binding affinities for pDNA (CIM C4 HLD, CIM-histamine and CIM-pyridine) were tested under hydrophobic interaction chromatography (HIC) conditions. SD efficiency for pDNA isoform separation was shown to be dependent on column selectivity for individual isoform, column efficiency and on ammonium sulfate (AS) concentration in loading buffer (binding strength). SD and negative mode elution often operate in parallel, therefore negative mode elution additionally influences the efficiency of the overall purification process. Optimisation of chromatographic conditions achieved 98% sc pDNA homogeneity and a dynamic binding capacity of over 1mg/mL at a relatively low concentration of AS. SDC was successfully implemented for the enrichment of sc pDNA for plasmid vectors of different sizes, and for separation of linear and and sc isoforms, independently of oc:sc isoform ratio, and flow-rate used. This study therefore identifies SDC as a promising new approach to large-scale pDNA purification, which is compatible with continuous, multicolumn chromatography systems, and could therefore be used to increase productivity of pDNA production in the future. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Rapid Sunspot Displacement Associated with Solar Eruptions

    Liu, Chang; Deng, N.; Wang, H.


    Many observational and modeling studies of solar eruptions merely treat photosphere as the lower boundary and assume no significant changes of magnetic fields anchoring there to occur during flares/CMEs. With increasing evidence of photospheric magnetic fields variations resulting from energy release in the upper atmosphere, Hudson, Fisher and Welsch (2008, ASP, 383, 221) proposed that the photosphere and even solar interior would respond in a back-reaction process to the coronal magnetic field restructuring. Inspired by this concept, we analyzed white-light images obtained with TRACE and report here rapid and permanent perturbation in the position of delta spot umbrae associated with five X-class flares. Our main results are the following: (1) The centroids of umbrae with opposite magnetic polarities undergo relative as well as overall displacement on the order of 1E3 km after flares/CMEs. (2) The estimated total kinetic energy associated with these motions (Ek) is on the order of 1E29 ergs and appears to correlate with the 6 mHZ seismic energy (Es) derived by the Monash group. (3) There appears correlation between both the Ek and Es corresponding to the velocity of CMEs. We suggest that: (1) sunspot displacement provides a direct observational evidence of the photospheric back-reaction and could potentially serve as an alternative excitation mechanism of seismic waves; (2) These could provide rational support to the back-reaction mechanism in the sense that its magnitude might be related to how violent the coronal magnetic field is disrupted. For selected events with good multiwavelength coverage, we also analyze in detail spatial as well as temporal relationship among the sunspot displacement, magnetic field changes, seismic sources, hard X-ray emissions, and overall flaring condition. This work is supported by NSF grants ATM 08-19662 and ATM 07-45744, and NASA grants NNX 08AQ90G, NNX 07AH78G, and NNX 08AQ32G.

  2. [Moist ablation of the corneal surface with the Er:YAG laser. Results of optimizing ablation].

    Bende, T; Jean, B; Matallana, M; Seiler, T; Steiner, R


    The Er:YAG laser, emitting light at 2.94 microns, may be an alternative to the 193 nm excimer laser for photorefractive keratectomy. Compared to the excimer laser, the ablation rate is very high. Surface roughness is also more pronounced than for the excimer laser. Using a precorneal liquid film, these two factors can be reduced, as shown in ablation experiments performed on porcine corneas. Thermal damage of the remaining corneal tissue is another side effect. There is no significant decrease in the amount of thermal damage with this new technique,--not even when the pulse length is reduced.

  3. Uncovering deformation processes from surface displacements

    Stramondo, Salvatore; Trasatti, Elisa; Albano, Matteo; Moro, Marco; Chini, Marco; Bignami, Christian; Polcari, Marco; Saroli, Michele


    Today, satellite remote sensing has reached a key role in Earth Sciences. In particular, Synthetic Aperture Radar (SAR) sensors and SAR Interferometry (InSAR) techniques are widely used for the study of dynamic processes occurring inside our living planet. Over the past 3 decades, InSAR has been applied for mapping topography and deformation at the Earth's surface. These maps are widely used in tectonics, seismology, geomorphology, and volcanology, in order to investigate the kinematics and dynamics of crustal faulting, the causes of postseismic and interseismic displacements, the dynamics of gravity driven slope failures, and the deformation associated with subsurface movement of water, hydrocarbons or magmatic fluids.

  4. Galvanic displacement of metals on semiconductor nanocrystals

    Johnson, Melanie; Kelly, Joel A.; Henderson, Eric J.; Veinot, Jonathan G. C.


    We report the galvanic displacement (GD) of germanium from germanium nanocrystals (Ge-NCs) with silver. The Ge-NCs are synthesized by reductive thermal processing of germanium suboxide sol-gel prepolymers. Thermal processing yields size-controlled oxide-embedded Ge-NCs, which are liberated by dissolution of the germanium oxide matrix in water. Subsequent exposure of the freestanding Ge-NCs to aqueous solutions of AgNO3 leads to deposition of silver nanostructures by GD. The resulting metal structures were analyzed by XRD, XPS, TEM and EDX, confirming deposition of elemental silver in a variety of shapes and sizes.

  5. Galvanic displacement of metals on semiconductor nanocrystals

    Johnson, Melanie; Kelly, Joel A; Henderson, Eric J; Veinot, Jonathan G C, E-mail: [University of Alberta, Department of Chemistry, Edmonton, AB, T6G 2G2 (Canada)


    We report the galvanic displacement (GD) of germanium from germanium nanocrystals (Ge-NCs) with silver. The Ge-NCs are synthesized by reductive thermal processing of germanium suboxide sol-gel prepolymers. Thermal processing yields size-controlled oxide-embedded Ge-NCs, which are liberated by dissolution of the germanium oxide matrix in water. Subsequent exposure of the freestanding Ge-NCs to aqueous solutions of AgNO{sub 3} leads to deposition of silver nanostructures by GD. The resulting metal structures were analyzed by XRD, XPS, TEM and EDX, confirming deposition of elemental silver in a variety of shapes and sizes.

  6. Simulating People Moving in Displacement Ventilated Rooms

    Mattsson, M.; Bjørn, Erik; Sandberg, M.

    A displacement ventilation system works better the more uni-directional the air flow through the ventilated room is: from floor to ceiling. Thus, from an air quality point of view, there should be as little vertical mixing of the room air as possible. It is therefore comprehensible that physical...... activity in the room -like peoples movements -in previous studies has been shown to influence the effectiveness of the ventilation. In this study we have compared results from previous tests, where a cylindrical person simulator was used, to results obtained when using a person simulator of more human...

  7. Two-Domain DNA Strand Displacement

    Cardelli, Luca


    We investigate the computing power of a restricted class of DNA strand displacement structures: those that are made of double strands with nicks (interruptions) in the top strand. To preserve this structural invariant, we impose restrictions on the single strands they interact with: we consider only two-domain single strands consisting of one toehold domain and one recognition domain. We study fork and join signal-processing gates based on these structures, and we show that these systems are amenable to formalization and to mechanical verification.

  8. Atomic displacement energy in amorphous compounds

    Sanditov, D. S.; Mashanov, A. A.


    Atomic displacement energy Δɛe in multicomponent sheet and lead-silicate glasses is calculated from the free activation energy of a viscous flow. The value of Δɛe is shown to remain constant in a rather wide range of temperatures in the glass transition region. Satisfactory agreement with calculations of Δɛe using the current formula incorporating the glass transition temperature and the fluctuation volume fraction frozen at this temperature is obtained. The validity of the above formula not only at the glass transition temperature but also in the temperature region adjacent to it is confirmed.

  9. Referenceless PRF thermometry with multi-echo processing to monitor prostate ablation

    Rieke, Viola; Kinsey, Adam M.; Nau, William H.; Diederich, Chris J.; Sommer, Graham; Pauly, Kim Butts


    Referenceless proton resonance frequency (PRF) shift thermometry provides a means to measure temperature changes during minimally invasive thermotherapy that is inherently robust to motion and tissue displacement. An extension to the referenceless method allows temperature estimation in the presence of phase discontinuities that occur at water/fat interfaces between prostate and periprostatic fat. Three images at different echo times are acquired and binary water and fat maps are generated from a Dixon reconstruction. For the background phase estimation, water and fat regions are treated separately and the phase offset between the two tissue types is determined. Here we present a new pulse sequence to acquire the necessary three images, which allows for temperature monitoring of the prostate with increased temporal resolution, optimal temperature resolution with respect to heating pattern of transurethral US applicators, and provides high resolution anatomical images. The method is demonstrated during in vivo thermal ablation of canine prostate.

  10. Generation of shear waves by laser in soft media in the ablative and thermoelastic regimes

    Grasland-Mongrain, Pol; Lu, Yuankang; Lesage, Frédéric; Catheline, Stefan; Cloutier, Guy


    This article describes the generation of elastic shear waves in a soft medium using a laser beam. Our experiments show two different regimes depending on laser energy. Physical modeling of the underlying phenomena reveals a thermoelastic regime caused by a local dilatation resulting from temperature increase and an ablative regime caused by a partial vaporization of the medium by the laser. The computed theoretical displacements are close to the experimental measurements. A numerical study based on the physical modeling gives propagation patterns comparable to those generated experimentally. These results provide a physical basis for the feasibility of a shear wave elastography technique (a technique that measures a soft solid stiffness from shear wave propagation) by using a laser beam.

  11. Concurrent Visualization of Acoustic Radiation Force Displacement and Shear Wave Propagation with 7T MRI.

    Yu Liu

    Full Text Available Manual palpation is a common and very informative diagnostic tool based on estimation of changes in the stiffness of tissues that result from pathology. In the case of a small lesion or a lesion that is located deep within the body, it is difficult for changes in mechanical properties of tissue to be detected or evaluated via palpation. Furthermore, palpation is non-quantitative and cannot be used to localize the lesion. Magnetic Resonance-guided Focused Ultrasound (MRgFUS can also be used to evaluate the properties of biological tissues non-invasively. In this study, an MRgFUS system combines high field (7T MR and 3 MHz focused ultrasound to provide high resolution MR imaging and a small ultrasonic interrogation region (~0.5 x 0.5 x 2 mm, as compared with current clinical systems. MR-Acoustic Radiation Force Imaging (MR-ARFI provides a reliable and efficient method for beam localization by detecting micron-scale displacements induced by ultrasound mechanical forces. The first aim of this study is to develop a sequence that can concurrently quantify acoustic radiation force displacements and image the resulting transient shear wave. Our motivation in combining these two measurements is to develop a technique that can rapidly provide both ARFI and shear wave velocity estimation data, making it suitable for use in interventional radiology. Secondly, we validate this sequence in vivo by estimating the displacement before and after high intensity focused ultrasound (HIFU ablation, and we validate the shear wave velocity in vitro using tissue-mimicking gelatin and tofu phantoms. Such rapid acquisitions are especially useful in interventional radiology applications where minimizing scan time is highly desirable.

  12. Development of laser ablation plasma by anisotropic self-radiation

    Ohnishi Naofumi


    Full Text Available We have proposed a method for reproducing an accurate solution of low-density ablation plasma by properly treating anisotropic radiation. Monte-Carlo method is employed for estimating Eddington tensor with limited number of photon samples in each fluid time step. Radiation field from ablation plasma is significantly affected by the anisotropic Eddington tensor. Electron temperature around the ablation surface changes with the radiation field and is responsible for the observed emission. An accurate prediction of the light emission from the laser ablation plasma requires a careful estimation of the anisotropic radiation field.

  13. Numerical simulation of copper ablation by ultrashort laser pulses

    Ding, PengJi; Li, YuHong


    Using a modified self-consistent one-dimensional hydrodynamic lagrangian fluid code, laser ablation of solid copper by ultrashort laser pulses in vacuum was simulated to study fundamental mechanisms and to provide a guide for drilling periodic microholes or microgratings on the metal surface. The simulated laser ablation threshold is a approximate constancy in femtosecond regime and increases as the square root of pulse duration in picosecond regime. The ablation depth as a function of pulse duration shows four different regimes and a minimum for a pulse duration of ~ 12ps for various laser fluences. The influence of laser-induced plasma shielding on ablation depth is also studied.

  14. Excimer laser ablation of thin titanium oxide films on glass

    Overschelde, O. van [Condensed Matter Physics Group, University of Mons-Hainaut, B-7000 Mons (Belgium); Dinu, S. [University of ' Valahia' , Targoviste (Romania); Guisbiers, G. [Condensed Matter Physics Group, University of Mons-Hainaut, B-7000 Mons (Belgium); Monteverde, F. [Materia Nova, Unit of Electronic Microscopy, B-7000 Mons (Belgium); Nouvellon, C. [Materia Nova, Inorganic and Analytical Chemistry, B-7000 Mons (Belgium); Wautelet, M. [Condensed Matter Physics Group, University of Mons-Hainaut, B-7000 Mons (Belgium)]. E-mail:


    Thin titanium dioxide films are deposited on glass substrates by magnetron sputter deposition. They are irradiated in air, by means of a KrF excimer laser. The ablation rate is measured as a function of the laser fluence per pulse, F, and of the number of pulses, N. Above a fluence threshold, the films are partially ablated. The ablated thickness does not vary linearly with N. This is the signature of a negative feedback between the film thickness and the ablation rate. The origin of this negative feedback is shown to be due to either thermal or electronic effects, or both. At high F, the film detachs from the substrate.

  15. Effects of laser ablation on cemented tungsten carbide surface quality

    Tan, J.L.; Butler, D.L.; Sim, L.M.; Jarfors, A.E.W. [Singapore Institute of Manufacturing Technology, Singapore (Singapore)


    Although laser micromachining has been touted as being the most promising way to fabricate micro tools, there has been no proper evaluation of the effects of laser ablation on bulk material properties. The current work demonstrates the effects of laser ablation on the properties of a cemented tungsten carbide surface. Of particular interest is the resultant increase in compressive residual stresses in the ablated surface. From this study it is seen that there are no adverse effects from laser ablation of cemented tungsten carbide that would preclude its use for the fabrication of micro-tools but a finishing process may not be avoidable. (orig.)

  16. Effects of laser ablation on cemented tungsten carbide surface quality

    Tan, J. L.; Butler, D. L.; Sim, L. M.; Jarfors, A. E. W.


    Although laser micromachining has been touted as being the most promising way to fabricate micro tools, there has been no proper evaluation of the effects of laser ablation on bulk material properties. The current work demonstrates the effects of laser ablation on the properties of a cemented tungsten carbide surface. Of particular interest is the resultant increase in compressive residual stresses in the ablated surface. From this study it is seen that there are no adverse effects from laser ablation of cemented tungsten carbide that would preclude its use for the fabrication of micro-tools but a finishing process may not be avoidable.

  17. Thermal character in organic polymers with nanojoule femtosecond laser ablation

    Xiaochang Ni(倪晓昌); Ching-Yue Wang(王清月); Yanfeng Li(栗岩峰); Minglie Hu(胡明列); Zhuan Wang(王专); Lu Chai(柴路)


    Ablation experiments with femtosecond (fs) laser pulse (pulse duration 37 fs, wavelength 800 nm) on organic polymers have been performed in air. The ablation threshold is found to be only several nanojoules. The diameters of the dots ablated in the organic polymers are influenced by the laser fluence and the number of laser pulses. It is observed that heat is diffused in a threadlike manner in all directions around the central focus region. Explanations of the observed phenomena are presented. A one-dimensional waveguide is also ablated in the organic polymers.

  18. Anterior ablatives of the gerund in the Mozarabic Chronicle

    Jana Mikulová


    Full Text Available In the Mozarabic Chronicle of 754, there are ablatives of the gerund that can be interpreted as anterior to the main predicate. Aspectual characteristics and context are considered to be the main factors for the previous interpretation. The use of the anterior ablative of the gerund gives evidence of the approximation between the present participle and the ablative of the gerund in Late Latin. The anterior ablative of the gerund, however, does not seem to be frequently used in contemporary texts.

  19. Pharmacological therapy following catheter ablation of atrial fibrillation.

    Rordorf, Roberto; Savastano, Simone; Gandolfi, Edoardo; Vicentini, Alessandro; Petracci, Barbara; Landolina, Maurizio


    Catheter ablation has been proven to be an effective treatment for patients with drug-resistant atrial fibrillation. Nevertheless its efficacy is limited to 60-80% of patients in different studies. Whether the use of pharmacological therapy after catheter ablation of atrial fibrillation might increase the procedural success rate is still a matter of debate. There is general agreement that antiarrhythmic drugs (AADs) are useful in the management of arrhythmias occurring in the very early period after catheter ablation (blanking period). On the contrary, limited data are available on the efficacy of AADs over a longer period. Some patients remain free of arrhythmia recurrences by the use of AADs that were ineffective before catheter ablation: whether this latter situation is to be considered a partial success of catheter ablation or a treatment failure, thus demanding a redo procedure, is still an open question. Some studies have also investigated the role of non-AADs [angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, statins and corticosteroids] in preventing atrial fibrillation recurrences after catheter ablation, reporting conflicting results. Whereas there is a general consensus on the use of anticoagulation therapy in the first phase after catheter ablation, no definite data are available on the proper long-term management of anticoagulation therapy after catheter ablation. This review focuses on the still open issue of what is the optimal pharmacological treatment of patients after catheter ablation of atrial fibrillation.

  20. CT-guided radiofrequency tumor ablation in children

    Botsa, Evanthia [National and Kapodistrian University of Athens, First Pediatric Clinic, Agia Sofia Children' s Hospital, Athens (Greece); Poulou, Loukia S.; Koundouraki, Antonia; Thanos, Loukas [Sotiria General Hospital for Chest Diseases, Department of Medical Imaging and Interventional Radiology, Athens (Greece); Koutsogiannis, Ioannis [General Military Hospital NIMTS, Department of Medical Imaging, Athens (Greece); Ziakas, Panayiotis D. [Warren Alpert Medical School of Brown University Rhode Island Hospital, Division of Infectious Diseases, Providence, RI (United States); Alexopoulou, Efthimia [Attikon University Hospital, Second Department of Radiology, Athens University School of Medicine, Athens (Greece)


    Image-guided radiofrequency ablation is a well-accepted technique of interventional oncology in adults. To evaluate the efficacy and safety of CT-guided radiofrequency ablation as a minimally invasive treatment for metastatic neoplasms in children. A total of 15 radiofrequency ablation sessions were performed in 12 children and young adults (median age 9.5; range 5-18 years) with metastatic malignancies. Seven children and young adults had secondary hepatic lesions, three had pulmonary and two had bone lesions. Radiofrequency ablation was performed under conscious sedation. The median lesion size was 1.7 cm (range 1.3-2.8 cm). The median time for ablation was 8 min (range 7-10 min). Radiofrequency procedures were technically successful in all tumors. Postablation imaging immediately after, and 1 month and 3 months after radiofrequency ablation showed total necrosis in all patients. At 6-month follow-up, three patients (all with lesion size >2 cm) had local recurrence and underwent a second radiofrequency ablation session. At 2-year follow-up no patient had recurrence of the treated tumor. Post-ablation syndrome occurred in four children. No major complication occurred. CT-guided radiofrequency tumor ablation was safe and efficient for palliative treatment in our cohort of patients. (orig.)

  1. Combining Percutaneous Pedicular and Extrapedicular Access for Tumor Ablation in a Thoracic Vertebral Body

    Cianfoni, Alessandro; Massari, Francesco; Ewing, Stacey; Persenaire, Maarten; Rumboldt, Zoran; Bonaldi, Giuseppe


    Summary We present a percutaneous modified technique to access large thoracic vertebral body lytic lesions, to increase the volume of tumor accessible to ablation, prior to cement augmentation. Tumor ablation and cavity creation-assisted percutaneous vertebroplasty was considered a palliative measure for structural stabilization in plasmocytoma involvement of the entire T8 vertebral body. Given the extent of osteolysis bilateral combined transpedicular and extrapedicular access to the vertebral body was undertaken to maximize the volume of cavity creation within the tumor. The combined transpedicular and extrapedicular access was feasible, uncomplicated, and successful in reaching all the quadrants of the anterior two thirds of the vertebral body. Slow, fluoroscopically monitored injection of high-viscosity cement resulted in a successful, desired cement distribution into the anterior two thirds of the vertebral body, spanning superior to inferior endplates, providing structural stability, in the absence of venous or epidural leakage. The technical modification described in this case yielded positive results while overcoming some of the limitations of the existing coblation device. This approach may offer an option for cement augmentation of extensive vertebral body lytic lesions, at increased risk for tumor displacement and extra-vertebral cement leakage. PMID:25363263

  2. Junctional rhythm occurring during AV nodal reentrant tachycardia ablation, is it different among Egyptians?

    Ayman M. Abdel Moteleb


    Conclusion: Junctional rhythm is a sensitive predictor of successful ablation. The pattern of JR is a useful predictor of successful ablation. Egyptian population has distinctive patterns of JR during AVNRT ablation.

  3. Grating Loaded Cantilevers for Displacement Measurements

    Karademir, Ertugrul; Olcum, Selim; Atalar, Abdullah; Aydinli, Atilla


    A cantilever with a grating coupler engraved on its tip is used for measuring displacement. The coupled light in the cantilever is guided to a single mode optical waveguide defined at the base of the cantilever. The grating period is 550 nm and is fabricated on a SOI wafer using nanoimprint lithography. The waveguide and the cantilever are defined by an RIE and cantilevers released by KOH and HF solutions. Light with 1550 nm wavelength, is directed onto the grating coupler and detected at the cleaved end of the SOI waveguide. The angle of incidence is controlled by a motorized rotary stage. Light couples into the waveguide at a characteristic angle with a full width at half maximum of approximately 6.9 mrads translating into a Q factor of 87.5. The displacement sensitivity is measured by driving the cantilever with a frequency controlled piezoelectric element. The modulation of the light at the waveguide output is lock-in detected by a biased infrared detector. The resulting 43%mrad-1 sensitivity can be increased with further optimization.

  4. Precision optical displacement measurements using biphotons

    Lyons, Kevin; Pang, Shengshi; Kwiat, Paul G.; Jordan, Andrew N.


    We propose and examine the use of biphoton pairs, such as those created in parametric down-conversion or four-wave mixing, to enhance the precision and the resolution of measuring optical displacements by position-sensitive detection. We show that the precision of measuring a small optical beam displacement with this method can be significantly enhanced by the correlation between the two photons, given the same optical mode. The improvement is largest if the correlations between the photons are strong, and falls off as the biphoton correlation weakens. More surprisingly, we find that the smallest resolvable parameter of a simple split detector scales as the inverse of the number of biphotons for small biphoton number ("Heisenberg scaling"), because the Fisher information diverges as the parameter to be estimated decreases in value. One usually sees this scaling only for systems with many entangled degrees of freedom. We discuss the transition for the split-detection scheme to the standard quantum limit scaling for imperfect correlations as the biphoton number is increased. An analysis of an N -pixel detector is also given to investigate the benefit of using a higher resolution detector. The physical limit of these metrology schemes is determined by the uncertainty in the birth zone of the biphoton in the nonlinear crystal.

  5. Displacing lateral meniscus masquerading as patella dislocation.

    Arendt, Elizabeth A; Fontboté, Cristián A; Rohr, Sara R


    To alert the treating clinician to an uncommon knee meniscal condition that often masquerades as a more common patella condition. Retrospective chart review of a series of cases was undertaken. A series of 12 knees in 11 patients were referred to an orthopaedic surgeon with a diagnosis of recurrent lateral patella dislocation. Three knees had undergone patella realignment surgery with continuance of symptoms. Eight patients had prior magnetic resonance images read as no meniscal pathology and no acute patella/patella retinacular injury. All patients presented for a consult with a similar history. Under anaesthesia, all knees had a stable patella as judged by physical examination. At the time of surgery, six patients had a frank tear in the lateral meniscus, all of which were readily displaceable. Six knees showed a displaceable lateral meniscus with attenuation but not a visible frank tear. Ten menisci were treated with repair, and two knees underwent partial lateral meniscectomies. Patient follow-up of minimally 18 months revealed no further episodes of "knee-cap dislocation" or symptoms of catching and locking. The clinician treating a patient with a history of a knee locking in flexion should have a high index of suspicion for a lateral meniscus tear or an unstable hypermobile lateral meniscus, despite patient report of perceived patella movement. History of symptoms occurring in knee flexion and attention to patella physical examination should be key factors in this diagnostic conundrum. Retrospective chart review, Level IV.

  6. Estimating Hydrologic Processes from Subsurface Soil Displacements

    Freeman, C. E.; Murdoch, L. C.; Germanovich, L.; MIller, S.


    Soil moisture and the processes that control it are important components of the hydrologic cycle, but measuring these processes remains challenging. We have developed a new measurement method that offers flexibility compared to existing technology. The approach is to measure small vertical displacements in the soil which responds proportionally to distributed surface load changes such as variation in the near-surface water content. The instrument may be installed at a depth of several meters to hundreds of meters below the surface. Because the measurement averaging region scales with the depth of the displacement measurements, this approach provides the means for estimating the soil moisture time series over tens of square meters to tens of thousands of square meters. The instrument developed for this application is called a Sand-X, which is short for Sand Extensometer. It is designed for applications in unconsolidated material, ranging from clay to sand. The instrument is simple and relatively inexpensive, and it can be installed in a boring made with a hand auger or with a small drill rig. Studies at the field scale are ongoing at a field site near Clemson, SC. The site is underlain by saprolite weathered primarily from biotite gneiss. Several Sand-X devices are installed at a field site that is instrumented for validating soil moisture, precipitation, and evapotranspiration estimates. These instruments are emplaced at a depth of 6 m and respond to the weight of a vehicle out to 18 m from the well. Calibration is performed by comparing precipitation measurements to the soil displacement response. For example, the coefficient for one installation is roughly 185 nm soil displacement/mm water content change. The resolution of the instrument is approximately 10 nm, so the Sand-X is capable of detecting changes of soil moisture on the order of tenths of one mm in compliant soils like saprolite. A typical soil displacement time series shows alternating periods of

  7. CT-guided Bipolar and Multipolar Radiofrequency Ablation (RF Ablation) of Renal Cell Carcinoma: Specific Technical Aspects and Clinical Results

    Sommer, C. M., E-mail: [University Hospital Heidelberg, INF 110, Department of Diagnostic and Interventional Radiology (Germany); Lemm, G.; Hohenstein, E. [Minimally Invasive Therapies and Nuclear Medicine, SLK Kliniken Heilbronn GmbH, Clinic for Radiology (Germany); Bellemann, N.; Stampfl, U. [University Hospital Heidelberg, INF 110, Department of Diagnostic and Interventional Radiology (Germany); Goezen, A. S.; Rassweiler, J. [Clinic for Urology, SLK Kliniken Heilbronn GmbH (Germany); Kauczor, H. U.; Radeleff, B. A. [University Hospital Heidelberg, INF 110, Department of Diagnostic and Interventional Radiology (Germany); Pereira, P. L. [Minimally Invasive Therapies and Nuclear Medicine, SLK Kliniken Heilbronn GmbH, Clinic for Radiology (Germany)


    Purpose. This study was designed to evaluate the clinical efficacy of CT-guided bipolar and multipolar radiofrequency ablation (RF ablation) of renal cell carcinoma (RCC) and to analyze specific technical aspects between both technologies. Methods. We included 22 consecutive patients (3 women; age 74.2 {+-} 8.6 years) after 28 CT-guided bipolar or multipolar RF ablations of 28 RCCs (diameter 2.5 {+-} 0.8 cm). Procedures were performed with a commercially available RF system (Celon AG Olympus, Berlin, Germany). Technical aspects of RF ablation procedures (ablation mode [bipolar or multipolar], number of applicators and ablation cycles, overall ablation time and deployed energy, and technical success rate) were analyzed. Clinical results (local recurrence-free survival and local tumor control rate, renal function [glomerular filtration rate (GFR)]) and complication rates were evaluated. Results. Bipolar RF ablation was performed in 12 procedures and multipolar RF ablation in 16 procedures (2 applicators in 14 procedures and 3 applicators in 2 procedures). One ablation cycle was performed in 15 procedures and two ablation cycles in 13 procedures. Overall ablation time and deployed energy were 35.0 {+-} 13.6 min and 43.7 {+-} 17.9 kJ. Technical success rate was 100 %. Major and minor complication rates were 4 and 14 %. At an imaging follow-up of 15.2 {+-} 8.8 months, local recurrence-free survival was 14.4 {+-} 8.8 months and local tumor control rate was 93 %. GFR did not deteriorate after RF ablation (50.8 {+-} 16.6 ml/min/1.73 m{sup 2} before RF ablation vs. 47.2 {+-} 11.9 ml/min/1.73 m{sup 2} after RF ablation; not significant). Conclusions. CT-guided bipolar and multipolar RF ablation of RCC has a high rate of clinical success and low complication rates. At short-term follow-up, clinical efficacy is high without deterioration of the renal function.

  8. Attenuation of Scalar Fluxes Measured with Spatially-displaced Sensors

    Horst, T. W.; Lenschow, D. H.


    Observations from the Horizontal Array Turbulence Study (HATS) field program are used to examine the attenuation of measured scalar fluxes caused by spatial separation between the vertical velocity and scalar sensors. The HATS data show that flux attenuation for streamwise, crosswind, and vertical sensor displacements are each a function of a dimensionless, stability-dependent parameter n m multiplied by the ratio of sensor displacement to measurement height. The scalar flux decays more rapidly with crosswind displacements than for streamwise displacements and decays more rapidly for stable stratification than for unstable stratification. The cospectral flux attenuation model of Kristensen et al. agrees well with the HATS data for streamwise sensor displacements, although it is necessary to include a neglected quadrature spectrum term to explain the observation that flux attenuation is often less with the scalar sensor downwind of the anemometer than for the opposite configuration. A simpler exponential decay model provides good estimates for crosswind sensor displacements, as well as for streamwise sensor displacements with stable stratification. A model similar to that of Lee and Black correctly predicts flux attenuation for a combination of streamwise and crosswind displacements, i.e. as a function of wind direction relative to the sensor displacement. The HATS data for vertical sensor displacements extend the near-neutral results of Kristensen et al. to diabatic stratification and confirm their finding that flux attenuation is less with the scalar sensor located below the anemometer than if the scalar sensor is displaced an equal distance either horizontally or above the anemometer.

  9. The effect of base pair mismatch on DNA strand displacement

    Broadwater, Bo


    DNA strand displacement is a key reaction in DNA homologous recombination and DNA mismatch repair and is also heavily utilized in DNA-based computation and locomotion. Despite its ubiquity in science and engineering, sequence-dependent effects of displacement kinetics have not been extensively characterized. Here, we measured toehold-mediated strand displacement kinetics using single-molecule fluorescence in the presence of a single base pair mismatch. The apparent displacement rate varied significantly when the mismatch was introduced in the invading DNA strand. The rate generally decreased as the mismatch in the invader was encountered earlier in displacement. Our data indicate that a single base pair mismatch in the invader stalls branch migration, and displacement occurs via direct dissociation of the destabilized incumbent strand from the substrate strand. We combined both branch migration and direct dissociation into a model, which we term, the concurrent displacement model, and used the first passage t...

  10. Micrometeorological processes driving snow ablation in an Alpine catchment

    R. Mott


    Full Text Available Mountain snow covers typically become patchy over the course of a melting season. The snow pattern during melt is mainly governed by the end of winter snow depth distribution and the local energy balance. The objective of this study is to investigate micrometeorological processes driving snow ablation in an Alpine catchment. For this purpose we combine a meteorological model (ARPS with a fully distributed energy balance model (Alpine3D. Turbulent fluxes above melting snow are further investigated by using data from eddy-correlation systems. We compare modelled snow ablation to measured ablation rates as obtained from a series of Terrestrial Laser Scanning campaigns covering a complete ablation season. The measured ablation rates indicate that the advection of sensible heat causes locally increased ablation rates at the upwind edges of the snow patches. The effect, however, appears to be active over rather short distances except for very strong wind conditions. Neglecting this effect, the model is able to capture the mean ablation rates for early ablation periods but strongly overestimates snow ablation once the fraction of snow coverage is below a critical value. While radiation dominates snow ablation early in the season, the turbulent flux contribution becomes important late in the season. Simulation results indicate that the air temperatures appear to overestimate the local air temperature above snow patches once the snow coverage is below a critical value. Measured turbulent fluxes support these findings by suggesting a stable internal boundary layer close to the snow surface causing a strong decrease of the sensible heat flux towards the snow cover. Thus, the existence of a stable internal boundary layer above a patchy snow cover exerts a dominant control on the timing and magnitude of snow ablation for patchy snow covers.

  11. Metal particles produced by laser ablation for ICP-MSmeasurements

    Gonzalez, Jhanis J.; Liu, Chunyi; Wen, Sy-Bor; Mao, Xianglei; Russo, Richard E.


    Pulsed laser ablation (266nm) was used to generate metal particles of Zn and Al alloys using femtosecond (150 fs) and nanosecond (4 ns) laser pulses with identical fluences of 50 J cm{sup -2}. Characterization of particles and correlation with Inductively Coupled Plasma Mass Spectrometer (ICP-MS) performance was investigated. Particles produced by nanosecond laser ablation were mainly primary particles with irregular shape and hard agglomerates (without internal voids). Particles produced by femtosecond laser ablation consisted of spherical primary particles and soft agglomerates formed from numerous small particles. Examination of the craters by white light interferometric microscopy showed that there is a rim of material surrounding the craters formed after nanosecond laser ablation. The determination of the crater volume by white light interferometric microscopy, considering the rim of material surrounding ablation craters, revealed that the volume ratio (fs/ns) of the craters on the selected samples was approximately 9 (Zn), 7 (NIST627 alloy) and 5 (NIST1711 alloy) times more ablated mass with femtosecond pulsed ablation compared to nanosecond pulsed ablation. In addition, an increase of Al concentration from 0 to 5% in Zn base alloys caused a large increase in the diameter of the particles, up to 65% while using nanosecond laser pulses. When the ablated particles were carried in argon into an ICP-MS, the Zn and Al signals intensities were greater by factors of {approx} 50 and {approx} 12 for fs vs. ns ablation. Femtosecond pulsed ablation also reduced temporal fluctuations in the {sup 66}Zn transient signal by a factor of ten compared to nanosecond laser pulses.

  12. Electroporation ablation: A new energy modality for ablation of arrhythmogenic cardiac substrate

    van Driel, VJHM


    At the very end of the Direct Current (DC) era, low-energy DC ablation was demonstrated to cause myocardial lesions by non-thermal irreversible electroporation (IRE) (permanent formation of pores in the cell membrane, leading to cell death), without arcing and/or barotrauma. To eliminate rather smal

  13. Similarities and differences in ablative and non-ablative iron oxide nanoparticle hyperthermia cancer treatment

    Petryk, Alicia A.; Misra, Adwiteeya; Kastner, Elliot J.; Mazur, Courtney M.; Petryk, James D.; Hoopes, P. Jack


    The use of hyperthermia to treat cancer is well studied and has utilized numerous delivery techniques, including microwaves, radio frequency, focused ultrasound, induction heating, infrared radiation, warmed perfusion liquids (combined with chemotherapy), and recently, metallic nanoparticles (NP) activated by near infrared radiation (NIR) and alternating magnetic field (AMF) based platforms. It has been demonstrated by many research groups that ablative temperatures and cytotoxicity can be produced with locally NP-based hyperthermia. Such ablative NP techniques have demonstrated the potential for success. Much attention has also been given to the fact that NP may be administered systemically, resulting in a broader cancer therapy approach, a lower level of tumor NP content and a different type of NP cancer therapy (most likely in the adjuvant setting). To use NP based hyperthermia successfully as a cancer treatment, the technique and its goal must be understood and utilized in the appropriate clinical context. The parameters include, but are not limited to, NP access to the tumor (large vs. small quantity), cancer cell-specific targeting, drug carrying capacity, potential as an ionizing radiation sensitizer, and the material properties (magnetic characteristics, size and charge). In addition to their potential for cytotoxicity, the material properties of the NP must also be optimized for imaging, detection and direction. In this paper we will discuss the differences between, and potential applications for, ablative and non-ablative magnetic nanoparticle hyperthermia.

  14. Thermal Performance of Ablative/ Ceramic Composite

    Adriana STEFAN


    Full Text Available A hybrid thermal protection system for atmospheric earth re-entry based on ablative materials on top of ceramic matrix composites is investigated for the protection of the metallic structure in oxidative and high temperature environment of the space vehicles. The paper focuses on the joints of ablative material (carbon fiber based CALCARB® or cork based NORCOAT TM and Ceramic Matrix Composite (CMC material (carbon fibers embedded in silicon carbide matrix, Cf/SiC, SICARBON TM or C/C-SiC using commercial high temperature inorganic adhesives. To study the thermal performance of the bonded materials the joints were tested under thermal shock at the QTS facility. For carrying out the test, the sample is mounted into a holder and transferred from outside the oven at room temperature, inside the oven at the set testing temperature (1100°C, at a heating rate that was determined during the calibration stage. The dwell time at the test temperature is up to 2 min at 1100ºC at an increasing rate of temperature up to ~ 9,5°C/s. Evaluating the atmospheric re-entry real conditions we found that the most suited cooling method is the natural cooling in air environment as the materials re-entering the Earth atmosphere are subjected to similar conditions. The average weigh loss was calculated for all the samples from one set, without differentiating the adhesive used as the weight loss is due to the ablative material consumption that is the same in all the samples and is up to 2%. The thermal shock test proves that, thermally, all joints behaved similarly, the two parts withstanding the test successfully and the assembly maintaining its integrity.

  15. Radiofrequency ablation for benign thyroid nodules.

    Bernardi, S; Stacul, F; Zecchin, M; Dobrinja, C; Zanconati, F; Fabris, B


    Benign thyroid nodules are an extremely common occurrence. Radiofrequency ablation (RFA) is gaining ground as an effective technique for their treatment, in case they become symptomatic. Here we review what are the current indications to RFA, its outcomes in terms of efficacy, tolerability, and cost, and also how it compares to the other conventional and experimental treatment modalities for benign thyroid nodules. Moreover, we will also address the issue of treating with this technique patients with cardiac pacemakers (PM) or implantable cardioverter-defibrillators (ICD), as it is a rather frequent occurrence that has never been addressed in detail in the literature.

  16. Solar cell contact formation using laser ablation

    Harley, Gabriel; Smith, David D.; Cousins, Peter John


    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  17. Solar cell contact formation using laser ablation

    Harley, Gabriel; Smith, David D.; Cousins, Peter John


    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline materiat layer; and forming conductive contacts in the plurality of contact holes.

  18. Solar cell contact formation using laser ablation

    Harley, Gabriel; Smith, David; Cousins, Peter


    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  19. Temperature mapping of thermal ablation using MRI.

    Samset, Eigil


    MRI is a unique tool for minimally invasive thermal ablation in that it can provide both targeting, monitoring and control during the procedure. Monitoring is achieved by using MRI temperature mapping. In this review the relevant physics is explained as a background to the state-of-the-art methods for computing temperature maps as well as the more cutting edge methods. The review covers both methods to monitor heating and cooling of tissue and explains temperature mapping using Proton Resonance Frequency shift, T1 mapping, diffusion mapping, R2* mapping and thermal models.

  20. An Alternative to Maxwell's Displacement Current

    Wolsky, Alan M


    Though sufficient for local conservation of charge, we show that Maxwells displacement current is not necessary. An alternative to the Ampere Maxwell equation is exhibited and the alternative s electric and magnetic fields and scalar and vector potentials are expressed in terms of the charge and current densities. The alternative describes a theory in which action is instantaneous and so may provide a good approximation to Maxwells equations where and when the finite speed of light can be neglected. The result is reminiscent of the Darwin approximation which arose from the study classical charged point particles to order (v/c)2 in the Lagrangian. Unlike Darwin, this approach does not depend on the constitution of the electric current. Instead, this approach grows from a straightforward revision of the Ampere Equation which revision enforces the local conservation of charge.

  1. Analog Computation by DNA Strand Displacement Circuits.

    Song, Tianqi; Garg, Sudhanshu; Mokhtar, Reem; Bui, Hieu; Reif, John


    DNA circuits have been widely used to develop biological computing devices because of their high programmability and versatility. Here, we propose an architecture for the systematic construction of DNA circuits for analog computation based on DNA strand displacement. The elementary gates in our architecture include addition, subtraction, and multiplication gates. The input and output of these gates are analog, which means that they are directly represented by the concentrations of the input and output DNA strands, respectively, without requiring a threshold for converting to Boolean signals. We provide detailed domain designs and kinetic simulations of the gates to demonstrate their expected performance. On the basis of these gates, we describe how DNA circuits to compute polynomial functions of inputs can be built. Using Taylor Series and Newton Iteration methods, functions beyond the scope of polynomials can also be computed by DNA circuits built upon our architecture.

  2. Displaced fracture through the anterior atlantal synchondrosis

    Thakar, Chrishan; Allibone, James [Royal National Orthopaedic Hospital NHS Trust, Department of Spinal Deformity, Stanmore, Middlesex (United Kingdom); Harish, Srinivasan [Royal National Orthopaedic Hospital NHS Trust, Department of Radiology, Stanmore, Middlesex (United Kingdom); Saifuddin, Asif [Royal National Orthopaedic Hospital NHS Trust, Department of Radiology, Stanmore, Middlesex (United Kingdom); University College, The Institute of Orthopaedics and Musculoskeletal Sciences, London (United Kingdom)


    In the acute setting, accurate radiological interpretation of paediatric cervical spine trauma can be difficult due to a combination of normal variants and presence of multiple synchondroses. We present a rare case of a fracture through the anterior atlantal synchondrosis in a paediatric spine. A five-year-old boy, who fell backwards onto the top of his head while swinging across on a monkey bar frame, presented with neck pain, cervical muscle spasm and decreased right lateral rotation and extension of his neck. Computed tomography showed a displaced diastatic fracture through right anterior atlantal synchondrosis. There are only 12 cases of paediatric C1 fractures reported in the world literature. The importance of considering this diagnosis in the appropriate clinical setting, and the normal variants in the paediatric atlas that can cause diagnostic dilemma to the interpreting radiologist, are discussed in this case report. (orig.)

  3. Superconducting inductive displacement detection of a microcantilever

    Vinante, A., E-mail: [Istituto di Fotonica e Nanotecnologie, CNR - Fondazione Bruno Kessler, I-38123 Povo, Trento (Italy)


    We demonstrate a superconducting inductive technique to measure the displacement of a micromechanical resonator. In our scheme, a type I superconducting microsphere is attached to the free end of a microcantilever and approached to the loop of a dc Superconducting Quantum Interference Device (SQUID) microsusceptometer. A local magnetic field as low as 100 μT, generated by a field coil concentric to the SQUID, enables detection of the cantilever thermomechanical noise at 4.2 K. The magnetomechanical coupling and the magnetic spring are in good agreement with image method calculations assuming pure Meissner effect. These measurements are relevant to recent proposals of quantum magnetomechanics experiments based on levitating superconducting microparticles.

  4. DNA strand displacement system running logic programs.

    Rodríguez-Patón, Alfonso; Sainz de Murieta, Iñaki; Sosík, Petr


    The paper presents a DNA-based computing model which is enzyme-free and autonomous, not requiring a human intervention during the computation. The model is able to perform iterated resolution steps with logical formulae in conjunctive normal form. The implementation is based on the technique of DNA strand displacement, with each clause encoded in a separate DNA molecule. Propositions are encoded assigning a strand to each proposition p, and its complementary strand to the proposition ¬p; clauses are encoded comprising different propositions in the same strand. The model allows to run logic programs composed of Horn clauses by cascading resolution steps. The potential of the model is demonstrated also by its theoretical capability of solving SAT. The resulting SAT algorithm has a linear time complexity in the number of resolution steps, whereas its spatial complexity is exponential in the number of variables of the formula. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  5. Axial flow positive displacement worm compressor

    Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)


    An axial flow positive displacement compressor has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first and second sections of a compressor assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first and second twist slopes in the first and second sections respectively. The first twist slopes are less than the second twist slopes. An engine including the compressor has in downstream serial flow relationship from the compressor a combustor and a high pressure turbine drivingly connected to the compressor by a high pressure shaft.

  6. Axial flow positive displacement worm gas generator

    Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)


    An axial flow positive displacement engine has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first, second, and third sections of a core assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first, second, and third twist slopes in the first, second, and third sections respectively. The first twist slopes are less than the second twist slopes and the third twist slopes are less than the second twist slopes. A combustor section extends axially downstream through at least a portion of the second section.

  7. DNA Strand-Displacement Timer Circuits.

    Fern, Joshua; Scalise, Dominic; Cangialosi, Angelo; Howie, Dylan; Potters, Leo; Schulman, Rebecca


    Chemical circuits can coordinate elaborate sequences of events in cells and tissues, from the self-assembly of biological complexes to the sequence of embryonic development. However, autonomously directing the timing of events in synthetic systems using chemical signals remains challenging. Here we demonstrate that a simple synthetic DNA strand-displacement circuit can release target sequences of DNA into solution at a constant rate after a tunable delay that can range from hours to days. The rates of DNA release can be tuned to the order of 1-100 nM per day. Multiple timer circuits can release different DNA strands at different rates and times in the same solution. This circuit can thus facilitate precise coordination of chemical events in vitro without external stimulation.

  8. Can Monkeys (Macaca mulatta) Represent Invisible Displacement?

    Filion, Christine M.; Washburn, David A.; Gulledge, Jonathan P.


    Four experiments were conducted to assess whether or not rhesus macaques (Macaca mulatta) could represent the unperceived movements of a stimulus. Subjects were tested on 2 computerized tasks, HOLE (monkeys) and LASER (humans and monkeys), in which subjects needed to chase or shoot at, respectively, a moving target that either remained visible or became invisible for a portion of its path of movement. Response patterns were analyzed and compared between target-visible and target-invisible conditions. Results of Experiments 1, 2, and 3 demonstrated that the monkeys are capable of extrapolating movement. That this extrapolation involved internal representation of the target's invisible movement was suggested but not confirmed. Experiment 4, however, demonstrated that the monkeys are capable of representing the invisible displacements of a stimulus.

  9. Dynamics of liquid-liquid displacement.

    Fetzer, Renate; Ramiasa, Melanie; Ralston, John


    Capillary driven liquid-liquid displacement in a system with two immiscible liquids of comparable viscosity was investigated by means of optical high speed video microscopy. For the first time, the impact of substrate wettability on contact line dynamics in liquid-liquid systems was studied. On all substrates, qualitatively different dynamics, in two distinct velocity regimes, were found. Hydrodynamic models apply to the fast stage of initial spreading, while nonhydrodynamic dissipation dominates contact line motion in a final stage at low speed, where the molecular kinetic theory (MKT) successfully captured the dynamics. The MKT model parameter values showed no systematic dependence on substrate wettability. This unexpected result is interpreted in terms of local contact line pinning.

  10. Anisotropic permeability in deterministic lateral displacement arrays

    Vernekar, Rohan; Loutherback, Kevin; Morton, Keith; Inglis, David


    We investigate anisotropic permeability of microfluidic deterministic lateral displacement (DLD) arrays. A DLD array can achieve high-resolution bimodal size-based separation of micro-particles, including bioparticles such as cells. Correct operation requires that the fluid flow remains at a fixed angle with respect to the periodic obstacle array. We show via experiments and lattice-Boltzmann simulations that subtle array design features cause anisotropic permeability. The anisotropy, which indicates the array's intrinsic tendency to induce an undesired lateral pressure gradient, can lead to off-axis flows and therefore local changes in the critical separation size. Thus, particle trajectories can become unpredictable and the device useless for the desired separation duty. We show that for circular posts the rotated-square layout, unlike the parallelogram layout, does not suffer from anisotropy and is the preferred geometry. Furthermore, anisotropy becomes severe for arrays with unequal axial and lateral gaps...

  11. Cold ablation driven by localized forces in alkali halides

    Hada, Masaki; Zhang, Dongfang; Pichugin, Kostyantyn; Hirscht, Julian; Kochman, Micha A.; Hayes, Stuart A.; Manz, Stephanie; Gengler, Regis Y. N.; Wann, Derek A.; Seki, Toshio; Moriena, Gustavo; Morrison, Carole A.; Matsuo, Jiro; Sciaini, German; Miller, R. J. Dwayne


    Laser ablation has been widely used for a variety of applications. Since the mechanisms for ablation are strongly dependent on the photoexcitation level, so called cold material processing has relied on the use of high-peak-power laser fluences for which nonthermal processes become dominant; often r

  12. Tissue temperatures and lesion size during irrigated tip catheter radiofrequency ablation: an in vitro comparison of temperature-controlled irrigated tip ablation, power-controlled irrigated tip ablation, and standard temperature-controlled ablation

    Petersen, H H; Chen, X; Pietersen, A


    The limited success rate of radiofrequency catheter ablation in patients with ventricular tachycardias related to structural heart disease may be increased by enlarging the lesion size. Irrigated tip catheter ablation is a new method for enlarging the size of the lesion. It was introduced...

  13. Radiofrequency ablation as initial therapy in paroxysmal atrial fibrillation

    Cosedis Nielsen, Jens; Johannessen, Arne; Raatikainen, Pekka;


    There are limited data comparing radiofrequency catheter ablation with antiarrhythmic drug therapy as first-line treatment in patients with paroxysmal atrial fibrillation.......There are limited data comparing radiofrequency catheter ablation with antiarrhythmic drug therapy as first-line treatment in patients with paroxysmal atrial fibrillation....

  14. Trowelable ablative coating composition and method of use

    Headrick, Stephen E. (Inventor); Hill, Roger L. (Inventor)


    A trowelable ablative coating composition is disclosed. The composition comprises an epoxy resin, an amide curing agent, glass microspheres and ground cork. A method for protecting a substrate is also disclosed. The method comprises applying the trowelable ablative coating discussed above to a substrate and curing the coating composition.

  15. Ablation techniques for primary and metastatic liver tumors


    Ablative treatment methods have emerged as safe and effective therapies for patients with primary andsecondary liver tumors who are not surgical candidatesat the time of diagnosis. This article reviews the currentliterature and describes the techniques, complicationsand results for radiofrequency ablation, microwaveablation, cryoablation, and irreversible electroporation.

  16. Low vulnerability of the right phrenic nerve to electroporation ablation

    van Driel, Vincent J. H. M.; Neven, KGEJ; van Wessel, Harri; Vink, Aryan; Doevendans, Pieter A. F. M.; Wittkampf, Fred H. M.


    BACKGROUND Circular electroporation ablation is a novel ablation modality for electrical pulmonary vein isolation. With a single 200-3 application, deep circular myocardial lesions can be created. However, the acute and chronic effects of this energy source on phrenic nerve (PN) function are unknown

  17. Unusual tumour ablations: report of difficult and interesting cases

    Mauri, Giovanni; Nicosia, Luca; Varano, Gianluca Maria; Shyn, Paul; Sartori, Sergio; Tombesi, Paola; Di Vece, Francesca; Orsi, Franco; Solbiati, Luigi


    Image-guided ablations are nowadays applied in the treatment of a wide group of diseases and in different organs and regions, and every day interventional radiologists have to face more difficult and unusual cases of tumour ablation. In the present case review, we report four difficult and unusual cases, reporting some tips and tricks for a successful image-guided treatment. PMID:28487751

  18. Investigations on laser hard tissue ablation under various environments

    Kang, H W [American Medical Systems-ICSV, San Jose, CA (United States); Oh, J [Division of Mechanical Engineering, Pukyong National University, Busan (Korea, Republic of); Welch, A J [Department of Biomedical Engineering, University of Texas at Austin, Austin, TX (United States)], E-mail:


    The purpose of this study was to investigate the effect of liquid environments upon laser bone ablation. A long-pulsed Er,Cr:YSGG laser was employed to ablate bovine bone tibia at various radiant exposures under dry, wet (using water or perfluorocarbon) and spray environmental conditions. Energy loss by the application of liquid during laser irradiation was evaluated, and ablation performance for all conditions was quantitatively measured by optical coherence tomography (OCT). Microscope images were also used to estimate thermal side effects in tissue after multiple-pulse ablation. Wet using water and spray conditions equally attenuated the 2.79 {mu}m wavelength laser beam. Higher transmission efficiency was obtained utilizing a layer of perfluorocarbon. Dry ablation exhibited severe carbonization due to excessive heat accumulation. Wet condition using water resulted in similar ablation volume to the dry case without carbonization. The perfluorocarbon layer produced the largest ablation volume but some carbonization due to the poor thermal conductivity. Spray induced clean cutting with slightly reduced efficiency. Liquid-assisted ablation provided significant beneficial effects such as augmented material removal and cooling/cleaning effects during laser osteotomy.

  19. Cold ablation driven by localized forces in alkali halides

    Hada, Masaki; Zhang, Dongfang; Pichugin, Kostyantyn; Hirscht, Julian; Kochman, Micha A.; Hayes, Stuart A.; Manz, Stephanie; Gengler, Regis Y. N.; Wann, Derek A.; Seki, Toshio; Moriena, Gustavo; Morrison, Carole A.; Matsuo, Jiro; Sciaini, German; Miller, R. J. Dwayne


    Laser ablation has been widely used for a variety of applications. Since the mechanisms for ablation are strongly dependent on the photoexcitation level, so called cold material processing has relied on the use of high-peak-power laser fluences for which nonthermal processes become dominant; often

  20. Percutaneous transluminal coronary rotary ablation with rotablator (European experience)

    M.E. Bertrand (Michel); J.M. Lablanche (Jean Marc); C. Bauters; P.P.T. de Jaegere (Peter); P.W.J.C. Serruys (Patrick); J. Meyer (Jurgen); U. Dietz; R. Erbel (Raimund)


    textabstractThis study reports the results from 3 European centers using rotary ablation with Rotablator, a device that is inserted into the coronary artery and removes atheroma by grinding it into millions of tiny fragments. Rotary ablation was performed in 129 patients. Primary success (reduction

  1. Ablation of various materials with intense XUV radiation

    Juha, Libor E-mail:; Krasa, Josef; Cejnarova, Andrea; Chvostova, Dagmar; Vorlicek, V.; Krzywinski, Jacek; Sobierajski, Ryszard; Andrejczuk, Andrzej; Jurek, Marek; Klinger, Dorota; Fiedorowicz, Henryk; Bartnik, Andrzej; Pfeifer, Miroslav; Kubat, Pavel; Pina, Ladislav; Kravarik, Jozef; Kubes, Pavel; Bakshaev, Y.L.; Korolev, V.D.; Chernenko, A.S.; Ivanov, M.I.; Scholz, Marek; Ryc, Leszek; Feldhaus, Josef; Ullschmied, Jiri; Boody, F.P


    Ablation behavior of organic polymer (polymethylmethacrylate) and elemental solid (silicon) irradiated by single pulses of XUV radiation emitted from Z-pinch, plasma-focus, and laser-produced plasmas was investigated. The ablation characteristics measured for these plasma-based sources will be compared with those obtained for irradiation of samples with XUV radiation generated by a free-electron laser.

  2. Rail gun performance and plasma characteristics due to wall ablation

    Ray, P. K.


    The experiment of Bauer, et al. (1982) is analyzed by considering wall ablation and viscous drag in the plasma. Plasma characteristics are evaluated through a simple fluid-mechanical analysis considering only wall ablation. By equating the energy dissipated in the plasma with the radiation heat loss, the average properties of the plasma are determined as a function of time.

  3. Transonic ablation flow regimes of high-Z pellets

    Kim, Hyoungkeun; Parks, Paul


    In this letter, we report results of numerical studies of the ablation of argon and neon pellets in tokamaks and compare them with theoretical predictions and studies of deuterium pellets. Results demonstrate the influence of atomic physics processes on the pellet ablation process.

  4. Low vulnerability of the right phrenic nerve to electroporation ablation

    van Driel, Vincent J. H. M.; Neven, KGEJ; van Wessel, Harri; Vink, Aryan; Doevendans, Pieter A. F. M.|info:eu-repo/dai/nl/164248366; Wittkampf, Fred H. M.|info:eu-repo/dai/nl/080434436

    BACKGROUND Circular electroporation ablation is a novel ablation modality for electrical pulmonary vein isolation. With a single 200-3 application, deep circular myocardial lesions can be created. However, the acute and chronic effects of this energy source on phrenic nerve (PN) function are

  5. Has multivessel angioplasty displaced surgical revascularization?

    King, S B; Ivanhoe, R J


    Over the years, PTCA has been proved a safe and effective therapy for single-vessel CAD. Given the record of favorable results for single-vessel angioplasty, the extension of angioplasty to multivessel CAD soon followed. The successful application of PTCA to multivessel disease has been facilitated by developments in balloon, guidewire, and guide catheter technology. Success rates have been satisfactory, and complications have remained acceptable. Furthermore, as an outgrowth of an understanding of the mechanism and effect of PTCA, guidelines have been developed to aid case selection. As emphasized earlier, these guidelines should weigh heavily in deciding whether to select PTCA as a treatment modality. Presently, in our opinion, PTCA has not yet completely displaced surgery for multivessel CAD. Surgical standby is required for safe PTCA, because emergency surgery can be lifesaving and limit myocardial infarction after failed angioplasty. It is doubtful that surgery will ever relinquish its position as the treatment of choice for left main coronary artery disease. Nor will elective surgery find wide application in single-vessel disease. Whether one mode of revascularization will emerge as the most efficacious for multivessel disease related to long-term survival, limitation of cardiac events, and cost will be addressed in the analysis of the ongoing randomized trials of surgery versus angioplasty. Andreas Gruentzig established that it was possible to work within the coronary artery in an alert and comfortable patient. Interventional cardiology has experienced rapid technologic growth. Many patients formerly treated with bypass surgery can be managed effectively with angioplasty. If effective bail-out methods for acute closure are proven effective and restenosis is limited to a small percentage of patients, angioplasty in some form will further displace CABG. Until those ultimate goals are achieved, the value of angioplasty compared with bypass surgery must rest

  6. Fluid trapping during capillary displacement in fractures

    Yang, Zhibing; Neuweiler, Insa; Méheust, Yves; Fagerlund, Fritjof; Niemi, Auli


    The spatial distribution of fluid phases and the geometry of fluid-fluid interfaces resulting from immiscible displacement in fractures cast decisive influence on a range of macroscopic flow parameters. Most importantly, these are the relative permeabilities of the fluids as well as the macroscopic irreducible saturations. They also influence parameters for component (solute) transport, as it usually occurs through one of the fluid phase only. Here, we present a numerical investigation on the critical role of aperture variation and spatial correlation on fluid trapping and the morphology of fluid phase distributions in a geological fracture. We consider drainage in the capillary dominated regime. The correlation scale, that is, the scale over which the two facing fracture walls are matched, varies among the investigated geometries between L/256 and L (self-affine fields), L being the domain/fracture length. The aperture variability is quantified by the coefficient of variation (δ), ranging among the various geometries from 0.05 to 0.25. We use an invasion percolation based model which has been shown to properly reproduce displacement patterns observed in previous experiments. We present a quantitative analysis of the size distribution of trapped fluid clusters. We show that when the in-plane curvature is considered, the amount of trapped fluid mass first increases with increasing correlation scale Lc and then decreases as Lc further increases from some intermediate scale towards the domain length scale L. The in-plane curvature contributes to smoothening the invasion front and to dampening the entrapment of fluid clusters of a certain size range that depends on the combination of random aperture standard deviation and spatial correlation.

  7. Systematic review of mini-implant displacement under orthodontic loading

    Manuel Nienkemper; Jörg Handschel; Dieter Drescher


    A growing number of studies have reported that mini-implants do not remain in exactly the same position during treatment, although they remain stable. The aim of this review was to collect data regarding primary displacement immediately straight after loading and secondary displacement over time. A systematic review was performed to investigate primary and secondary displacement. The amount and type of displacement were recorded. A total of 27 studies were included. Sixteen in vitro studies or studies using finite element analysis addressed primary displacement, and nine clinical studies and two animal studies addressed secondary displacement. Significant primary displacement was detected (6.4-24.4 mm) for relevant orthodontic forces (0.5-2.5 N). The mean secondary displacement ranged from 0 to 2.7 mm for entire mini-implants. The maximum values for each clinical study ranged from 1.0 to 4.1 mm for the head, 1.0 to 1.5 for the body and 1.0 to 1.92 mm for the tail part. The most frequent type of movement was controlled tipping or bodily movement. Primary displacement did not reach a clinically significant level. However, clinicians can expect relevant secondary displacement in the direction of force. Consequently, decentralized insertion within the inter-radicular space, away from force direction, might be favourable. More evidence is needed to provide quantitative recommendations.

  8. Synthesis of Ag@Silica Nanoparticles by Assisted Laser Ablation

    González-Castillo, Jr.; Rodriguez, E.; Jimenez-Villar, E.; Rodríguez, D.; Salomon-García, I.; de Sá, Gilberto F.; García-Fernández, T.; Almeida, DB; Cesar, CL; Johnes, R.; Ibarra, Juana C.


    This paper reports the synthesis of silver nanoparticles coated with porous silica (Ag@Silica NPs) using an assisted laser ablation method. This method is a chemical synthesis where one of the reagents (the reducer agent) is introduced in nanometer form by laser ablation of a solid target submerged in an aqueous solution. In a first step, a silicon wafer immersed in water solution was laser ablated for several minutes. Subsequently, an AgNO3 aliquot was added to the aqueous solution. The redox reaction between the silver ions and ablation products leads to a colloidal suspension of core-shell Ag@Silica NPs. The influence of the laser pulse energy, laser wavelength, ablation time, and Ag+ concentration on the size and optical properties of the Ag@Silica NPs was investigated. Furthermore, the colloidal suspensions were studied by UV-VIS-NIR spectroscopy, X-Ray diffraction, and high-resolution transmission electron microscopy (HRTEM).

  9. Chemothermal Therapy for Localized Heating and Ablation of Tumor

    Zhong-Shan Deng


    Full Text Available Chemothermal therapy is a new hyperthermia treatment on tumor using heat released from exothermic chemical reaction between the injected reactants and the diseased tissues. With the highly minimally invasive feature and localized heating performance, this method is expected to overcome the ubiquitous shortcomings encountered by many existing hyperthermia approaches in ablating irregular tumor. This review provides a relatively comprehensive review on the latest advancements and state of the art in chemothermal therapy. The basic principles and features of two typical chemothermal ablation strategies (acid-base neutralization-reaction-enabled thermal ablation and alkali-metal-enabled thermal/chemical ablation are illustrated. The prospects and possible challenges facing chemothermal ablation are analyzed. The chemothermal therapy is expected to open many clinical possibilities for precise tumor treatment in a minimally invasive way.

  10. Radiofrequency Ablation for Treatment of Symptomatic Uterine Fibroids

    Siân Jones


    Full Text Available The use of thermal energy-based systems to treat uterine fibroids has resulted in a plethora of devices that are less invasive and potentially as effective in reducing symptoms as traditional options such as myomectomy. Most thermal ablation devices involve hyperthermia (heating of tissue, which entails the conversion of an external electromagnetic or ultrasound waves into intracellular mechanical energy, generating heat. What has emerged from two decades of peer-reviewed research is the concept that hyperthermic fibroid ablation, regardless of the thermal energy source, can create large areas of necrosis within fibroids resulting in reductions in fibroid volume, associated symptoms and the need for reintervention. When a greater percentage of a fibroid's volume is ablated, symptomatic relief is more pronounced, quality of life increases, and it is more likely that such improvements will be durable. We review radiofrequency ablation (RFA, one modality of hyperthermic fibroid ablation.

  11. Pulsed Tm:YAG laser ablation of knee joint tissues

    Shi, Wei-Qiang; Vari, Sandor G.; Duffy, J. T.; Miller, J. M.; Weiss, Andrew B.; Fishbein, Michael C.; Grundfest, Warren S.


    We investigated the effect of a free-running 2.01 micron pulsed Tm:YAG laser on bovine knee joint tissues. Ablation rates of fresh fibrocartilage, hyaline cartilage, and bone were measured in saline as a function of laser fluence (160 - 640 J/cm2) and fiber core size (400 and 600 microns). All tissues could be effectively ablated and the ablation rate increased linearly with the increasing fluence. Use of fibers of different core sizes, while maintaining constant energy fluence, did not result in significant difference in ablation rate. Histology analyses of the ablated tissue samples reveal average Tm:YAG radiation induced thermal damage (denatunalization) zones ranging between 130 and 540 microns, depending on the laser parameters and the tissue type.

  12. Dynamics of Laser Ablation in Superfluid ^4{He}

    Buelna, X.; Popov, E.; Eloranta, J.


    Pulsed laser ablation of metal targets immersed in superfluid ^4{He} is visualized by time-resolved shadowgraph photography and the products are analyzed by post-experiment atomic force microscopy (AFM) measurements. The expansion dynamics of the gaseous ablation half-bubble on the target surface appears underdamped and follows the predicted behavior for the thermally induced bubble growth mechanism. An inherent instability of the ablation bubble appears near its maximum radius and no tightly focused cavity collapse or rebound events are observed. During the ablation bubble retreat phase, the presence of sharp edges in the target introduces flow patterns that lead to the creation of large classical vortex rings. Furthermore, on the nanometer scale, AFM data reveal that the metal nanoparticles created by laser ablation are trapped in spherical vortex tangles and quantized vortex rings present in the non-equilibrium liquid.

  13. Pulsed laser ablation of solids basics, theory and applications

    Stafe, Mihai; Puscas, Niculae N


    The book introduces ‘the state of the art' of pulsed laser ablation and its applications. It is based on recent theoretical and experimental studies. The book reaches from the basics to advanced topics of pulsed laser ablation. Theoretical and experimental fundamental phenomena involved in pulsed laser ablation are discussed with respect to material properties, laser wavelength, fluence and intensity regime of the light absorbed linearly or non-linearly in the target material. The energy absorbed by the electrons leads to atom/molecule excitation, ionization and/or direct chemical bond breaking and is also transferred to the lattice leading to material heating and phase transitions. Experimental  non-invasive optical methods for analyzing these phenomena in real time are described. Theoretical models for pulsed laser ablation and phase transitions induced by laser beams and laser-vapour/plasma interaction during the plume expansion above the target are also presented. Calculations of the ablation speed and...

  14. Laser ablation with applied magnetic field for electric propulsion

    Batishcheva, Alla; Batishchev, Oleg; Cambier, Jean-Luc


    Using ultrafast lasers with tera-watt-level power allows efficient ablation and ionization of solid-density materials [1], creating dense and hot (˜100eV) plasma. We propose ablating small droplets in the magnetic nozzle configurations similar to mini-helicon plasma source [2]. Such approach may improve the momentum coupling compared to ablation of solid surfaces and facilitate plasma detachment. Results of 2D modeling of solid wire ablation in the applied magnetic field are presented and discussed. [4pt] [1] O. Batishchev et al, Ultrafast Laser Ablation for Space Propulsion, AIAA technical paper 2008-5294, -16p, 44th JPC, Hartford, 2008.[0pt] [2] O. Batishchev and J.L. Cambier, Experimental Study of the Mini-Helicon Thruster, Air Force Research Laboratory Report, AFRL-RZ-ED-TR-2009-0020, 2009.

  15. A numerical algorithm for magnetohydrodynamics of ablated materials.

    Lu, Tianshi; Du, Jian; Samulyak, Roman


    A numerical algorithm for the simulation of magnetohydrodynamics in partially ionized ablated material is described. For the hydro part, the hyperbolic conservation laws with electromagnetic terms is solved using techniques developed for free surface flows; for the electromagnetic part, the electrostatic approximation is applied and an elliptic equation for electric potential is solved. The algorithm has been implemented in the frame of front tracking, which explicitly tracks geometrically complex evolving interfaces. An elliptic solver based on the embedded boundary method were implemented for both two- and three-dimensional simulations. A surface model on the interface between the solid target and the ablated vapor has also been developed as well as a numerical model for the equation of state which accounts for atomic processes in the ablated material. The code has been applied to simulations of the pellet ablation in a magnetically confined plasma and the laser-ablated plasma plume expansion in magnetic fields.

  16. Computational modeling of ultra-short-pulse ablation of enamel

    London, R.A.; Bailey, D.S.; Young, D.A. [and others


    A computational model for the ablation of tooth enamel by ultra-short laser pulses is presented. The role of simulations using this model in designing and understanding laser drilling systems is discussed. Pulses of duration 300 sec and intensity greater than 10{sup 12} W/cm{sup 2} are considered. Laser absorption proceeds via multi-photon initiated plasma mechanism. The hydrodynamic response is calculated with a finite difference method, using an equation of state constructed from thermodynamic functions including electronic, ion motion, and chemical binding terms. Results for the ablation efficiency are presented. An analytic model describing the ablation threshold and ablation depth is presented. Thermal coupling to the remaining tissue and long-time thermal conduction are calculated. Simulation results are compared to experimental measurements of the ablation efficiency. Desired improvements in the model are presented.

  17. Cardiac Radiofrequency Ablation: A Clinical Update for Nurses.

    Shoulders, Bridget; Mauriello, Jillian; Shellman, Tamika; Follett, Corrinne


    The field of electrophysiology (EP) has rapidly evolved from a focus on diagnostic procedures to an emphasis on interventions. Many cardiac arrhythmias traditionally treated with antiarrhythmic agents, cardioversion, or cardiac surgery are now routinely cured with cardiac ablation. To optimally manage the care of cardiac ablation patients, it is essential that nurses have an understanding of the EP procedures and related nursing implications. There are extensive evidence-based resources available in the medical literature; however, there are limited publications geared toward nurses caring for cardiac ablation patients.This article provides an overview of EP diagnostic and cardiac radio-frequency ablation procedures for select atrial and ventricular tachyarrhythmias. Evidence-based nursing practices related to postprocedure care will be addressed. The objective of this article is to increase nurses' knowledge of common cardiac ablation procedures and the nursing management of the patient postprocedure.

  18. Oestrogen sulfotransferase ablation sensitizes mice to sepsis.

    Chai, Xiaojuan; Guo, Yan; Jiang, Mengxi; Hu, Bingfang; Li, Zhigang; Fan, Jie; Deng, Meihong; Billiar, Timothy R; Kucera, Heidi R; Gaikwad, Nilesh W; Xu, Meishu; Lu, Peipei; Yan, Jiong; Fu, Haiyan; Liu, Youhua; Yu, Lushan; Huang, Min; Zeng, Su; Xie, Wen


    Sepsis is the host's deleterious systemic inflammatory response to microbial infections. Here we report an essential role for the oestrogen sulfotransferase (EST or SULT1E1), a conjugating enzyme that sulfonates and deactivates estrogens, in sepsis response. Both the caecal ligation and puncture (CLP) and lipopolysaccharide models of sepsis induce the expression of EST and compromise the activity of oestrogen, an anti-inflammatory hormone. Surprisingly, EST ablation sensitizes mice to sepsis-induced death. Mechanistically, EST ablation attenuates sepsis-induced inflammatory responses due to compromised oestrogen deactivation, leading to increased sepsis lethality. In contrast, transgenic overexpression of EST promotes oestrogen deactivation and sensitizes mice to CLP-induced inflammatory response. The induction of EST by sepsis is NF-κB dependent and EST is a NF-κB-target gene. The reciprocal regulation of inflammation and EST may represent a yet-to-be-explored mechanism of endocrine regulation of inflammation, which has an impact on the clinical outcome of sepsis.

  19. Radiofrequency ablation of idiopathic ventricular tachycardia

    Vohra, J.; Shah, A.; Hua, W.; Gerloff, J.; Riters, A. [Royal Melbourne Hospital, Melbourne, VIC (Australia)


    Radiofrequency ablation (RFA) has been shown to be very effective in the treatment of supraventricular tachycardias and has replaced surgical ablation. Only a few reports of RFA for idiopathic ventricular tachycardia (VT) have appeared in the literature during the last two years. This paper presents our experience with RFA for idiopathic VT in 19 patients. In all patients the diagnostic study and therapeutic RFA were combined in a single procedure. Pacemapping were used to guide the site of RFA in patients with VT arising from the RV. Local activation time (LAT), Purkinje potentials (PP) and pacemapping were used to guide RFA in those patients with LV septal tachycardias. Idiopathic VT frequently arises from the RVOT and inferobasal portion of the LV septum. These tachycardias can be diagnosed on clinical and ECG grounds. RFA for idiopathic VT arising from these areas has a high success rate and this mode of treatment should be considered as a nonpharmacological curative treatment for symptomatic patients. 13 refs., 3 tabs., 4 figs.

  20. CT Guided Laser Ablation of Osteoid Osteoma

    Manohar Kachare


    Full Text Available To present our experience of Computed Tomography (CT guided laser ablation of radiologically proven osteoid osteoma in the inter trochantric region of the femur. A19 year old female presented with severe pain in left upper thigh region since 6-7 months, which was exaggerated during nights and was relived on taking oral Non Steroid Anti Inflammatory Drugs (NSAIDs. On CT scan hypodense lesion with surrounding dense sclerosis noted in intertrochanteric region in left femur. Magnetic Resonance Imaging (MRI revealed small focal predominantly cortical, oval lytic lesion in the intertrochanteric region which appeared hypointense on T1 Weighted Image (T1WI and hyperintense on T2 Weighted Image (T2WI and Short Tau Inversion Recovery (STIR image. Diffuse extensive sclerosis and hyperostosis of bone was noted surrounding the lesion appearing hypointense on T1W and T2W images. Under local anesthesia the laser fibre was inserted in the nidus under CT guidance through bone biopsy needle and 1800 joules energy delivered in the lesion continuous mode. Complete relief of pain noted after 24 hours after the treatment. CT guided LASER ablation is a safe, simple and effective method of treatment for osteoid osteoma.

  1. Pulmonary radiofrequency ablation (Part 1): current state.

    Plasencia Martínez, J M


    The risks involved in surgical treatment and conventional radiotherapy in patients with early lung cancer or lung metastases often make these treatments difficult to justify. However, on the other hand, it is also unacceptable to allow these lesions to evolve freely because, left untreated, these neoplasms will usually lead to the death of the patient. In recent years, alternative local therapies have been developed, such as pulmonary radiofrequency ablation, which has proven to increase survival with a minimal risk of complications. There are common recommendations for these treatments, and although the specific indications for using one technique or another have yet to be established, there are clearly defined situations that will determine the outcome of the treatment. It is important to know these situations, because appropriate patient selection is essential for therapeutic success. This article aims to describe the characteristics and constraints of pulmonary radiofrequency ablation and to outline its role in thoracic oncology in light of the current evidence. Copyright © 2014 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

  2. Conditional Lineage Ablation to Model Human Diseases

    Lee, Paul; Morley, Gregory; Huang, Qian; Fischer, Avi; Seiler, Stephanie; Horner, James W.; Factor, Stephen; Vaidya, Dhananjay; Jalife, Jose; Fishman, Glenn I.


    Cell loss contributes to the pathogenesis of many inherited and acquired human diseases. We have developed a system to conditionally ablate cells of any lineage and developmental stage in the mouse by regulated expression of the diphtheria toxin A (DTA) gene by using tetracycline-responsive promoters. As an example of this approach, we targeted expression of DTA to the hearts of adult mice to model structural abnormalities commonly observed in human cardiomyopathies. Induction of DTA expression resulted in cell loss, fibrosis, and chamber dilatation. As in many human cardiomyopathies, transgenic mice developed spontaneous arrhythmias in vivo, and programmed electrical stimulation of isolated-perfused transgenic hearts demonstrated a strikingly high incidence of spontaneous and inducible ventricular tachycardia. Affected mice showed marked perturbations of cardiac gap junction channel expression and localization, including a subset with disorganized epicardial activation patterns as revealed by optical action potential mapping. These studies provide important insights into mechanisms of arrhythmogenesis and suggest that conditional lineage ablation may have wide applicability for studies of disease pathogenesis.

  3. Post-Ablation Endometrial Carcinoma (PAEC) Following Radiofrequency Endometrial Ablation: A Case Report and Its Implications for Management of Endometrial Ablation Failures.

    Wortman, Morris; Dawkins, Josette C


    Endometrial ablation (EA) has become one of the most commonly performed gynecologic procedures in the United States and other developed countries. Global endometrial ablation (GEA) devices have supplanted resectoscopic ablation primarily because they have brought with them technical simplicity and unprecedented safety. These devices, all of which received FDA approval between 1997 and 2001, are typically used to treat abnormal uterine bleeding (AUB) in premenopausal women. Several million women in the US who have undergone a previous EA procedure are about to enter the risk pool for the development of endometrial cancer (EC). Ours is the 18th reported case of post-ablation endometrial carcinoma (PAEC) in the English literature. This case underscores the diagnostic challenges faced in evaluating women with a history of a previous EA who cannot be properly evaluated with conventional techniques such as endometrial biopsy and sonohysterography.

  4. On the use of a laser ablation as a laboratory seismic source

    Shen, Chengyi; Brito, Daniel; Diaz, Julien; Zhang, Deyuan; Poydenot, Valier; Bordes, Clarisse; Garambois, Stéphane


    Mimic near-surface seismic imaging conducted in well-controlled laboratory conditions is potentially a powerful tool to study large scale wave propagations in geological media by means of upscaling. Laboratory measurements are indeed particularly suited for tests of theoretical modellings and comparisons with numerical approaches. We have developed an automated Laser Doppler Vibrometer (LDV) platform, which is able to detect and register broadband nano-scale displacements on the surface of various materials. This laboratory equipment has already been validated in experiments where piezoelectric transducers were used as seismic sources. We are currently exploring a new seismic source in our experiments, a laser ablation, in order to compensate some drawbacks encountered with piezoelectric sources. The laser ablation source is considered to be an interesting ultrasound wave generator since the 1960s. It was believed to have numerous potential applications such as the Non-Destructive Testing (NDT) and the measurements of velocities and attenuations in solid samples. We aim at adapting and developing this technique into geophysical experimental investigations in order to produce and explore complete micro-seismic data sets in the laboratory. We will first present the laser characteristics including its mechanism, stability, reproducibility, and will evaluate in particular the directivity patterns of such a seismic source. We have started by applying the laser ablation source on the surfaces of multi-scale homogeneous aluminum samples and are now testing it on heterogeneous and fractured limestone cores. Some other results of data processing will also be shown, especially the 2D-slice V P and V S tomographic images obtained in limestone samples. Apart from the experimental records, numerical simulations will be carried out for both the laser source modelling and the wave propagation in different media. First attempts will be done to compare quantitatively the

  5. Pulsed laser generation of ultrasound in a metal plate between the melting and ablation thresholds

    Every, A. G., E-mail: [School of Physics, University of the Witwatersrand, PO Wits 2050 (South Africa); Utegulov, Z. N., E-mail: [Department of Physics, School of Science and Technology, Nazarbayev University, Astana 010000 (Kazakhstan); Veres, I. A., E-mail: [RECENDT Research Center for Non Destructive Testing GmbH, A-4040 Linz (Austria)


    The generation of ultrasound in a metal plate exposed to nanosecond pulsed laser heating, sufficient to cause melting but not ablation, is treated. Consideration is given to the spatial and temporal profiles of the laser pulse, penetration of the laser beam into the sample, the evolution of the melt pool, and thermal conduction in the melt and surrounding solid. The excitation of the ultrasound takes place over a few nanoseconds, and occurs predominantly within the thermal diffusion length of a micron or so beneath the surface. Because of this, the output of the thermal simulations can be represented as axially symmetric transient radial and normal surface force distributions. The epicentral displacement response at the opposite surface to these forces is obtained by two methods, the one based on the elastodynamic Green’s functions for plate geometry determined by the Cagniard generalized ray method, and the other using a finite element numerical method. The two approaches are in very close agreement. Numerical simulations are reported of the epicentral displacement response of a 3.12mm thick tungsten plate irradiated with a 4 ns pulsed laser beam with Gaussian spatial profile, at intensities below and above the melt threshold. Comparison is made between results obtained using available temperature dependent thermophysical data, and room temperature materials constants except near the melting point.

  6. DENSE: Displacement Encoding with Stimulated Echoes in Cardiac Functional MRI

    Aletras, Anthony H.; Ding, Shujun; Balaban, Robert S.; Wen, Han


    Displacement encoding with stimulated echoes (DENSE) was developed for high-resolution myocardial displacement mapping. Pixel phase is modulated by myocardial displacement and data spatial resolution is limited only by pixel size. 2D displacement vector maps were generated for the systolic action in canines with 0.94 × 1.9 mm nominal in-plane resolution and 2.3 mm/π displacement encoding. A radial strain of 0.208 was measured across the free left ventricular wall over 105 ms during systole. DENSE displacement maps require small first-order gradient moments for encoding. DENSE magnitude images exhibit black-blood contrast which allows for better myocardial definition and reduced motion-related artifacts.

  7. Percutaneous Renal Tumor Ablation: Radiation Exposure During Cryoablation and Radiofrequency Ablation

    McEachen, James C., E-mail: [Mayo Clinic, Division of Preventive, Occupational, and Aerospace Medicine (United States); Leng, Shuai; Atwell, Thomas D. [Mayo Clinic, Department of Radiology (United States); Tollefson, Matthew K. [Mayo Clinic, Department of Urology (United States); Friese, Jeremy L. [Mayo Clinic, Department of Radiology (United States); Wang, Zhen; Murad, M. Hassan [Mayo Clinic, Division of Preventive, Occupational, and Aerospace Medicine (United States); Schmit, Grant D. [Mayo Clinic, Department of Radiology (United States)


    IntroductionOnce reserved solely for non-surgical cases, percutaneous ablation is becoming an increasingly popular treatment option for a wider array of patients with small renal masses and the radiation risk needs to be better defined as this transition continues.Materials and MethodsRetrospective review of our renal tumor ablation database revealed 425 patients who underwent percutaneous ablation for treatment of 455 renal tumors over a 5-year time period. Imparted radiation dose information was reviewed for each procedure and converted to effective patient dose and skin dose using established techniques. Statistical analysis was performed with each ablative technique.ResultsFor the 331 cryoablation procedures, the mean DLP was 6987 mGycm (SD = 2861) resulting in a mean effective dose of 104.7 mSv (SD = 43.5) and the mean CTDI{sub vol} was 558 mGy (SD = 439) resulting in a mean skin dose of 563.2 mGy (SD = 344.1). For the 124 RFA procedures, the mean DLP was 3485 mGycm (SD = 1630) resulting in a mean effective dose of 50.3 mSv (SD = 24.0) and the mean CTDI{sub vol} was 232 mGy (SD = 149) resulting in a mean skin dose of 233.2 mGy (SD = 117.4). The difference in patient radiation exposure between the two renal ablation techniques was statistically significant (p < 0.001).ConclusionBoth cryoablation and RFA imparted an average skin dose that was well below the 2 Gy deterministic threshold for appreciable sequela. Renal tumor cryoablation resulted in a mean skin and effective radiation dose more than twice that for RFA. The radiation exposure for both renal tumor ablation techniques was at the high end of the medical imaging radiation dose spectrum.

  8. Distal displacement of the maxilla and the upper first molar.

    Baumrind, S; Molthen, R; West, E E; Miller, D M


    Data from a sample of 198 Class II cases treated with various appliances which deliver distally directed forces to the maxilla were examined to determine the frequency of absolute distal displacement of the upper first molar and of the maxilla. Analysis revealed that such distal displacement is possible and that it is, in fact, a frequent finding following treatment. Long-range stability of distal displacement was not assessed.

  9. Displacement desorption test of coalbed methane and its mechanism exploring

    ZHANG Suian; HUO Yongzhong; YE Jianping; TANG Shuheng; MA Dongmin


    Through the test of CH4 displaced by CO2 using the coal sample as the adsorbent, this paper has found the coalbed methane (CBM) displacement desorption phenomenon under the natural conditions and CBM mining conditions. With the help of the adsorption theory of the modern physical chemistry and interfacial chemistry, the CBM competitive adsorption and displacement desorption mechanism are intensively discussed, and a new path for studying the CBM desorption mechanism in the CBM exploitation process is explored.

  10. Test Rig Design For Compact Variable Displacement Vane Pump

    Chawla, Pratik; Jenkins, Ryan; Ivantysynova, Monika


    Variable displacement vane pumps (VDVP) are one type of positive displacement pumps used in automatic transmission vehicles for lubricating the gears, cooling the transmission and actuating the clutches. Though fixed displacement pumps are widely used, they output a constant effective flow at a given speed. Depending on pump sizing considerations, the pump can be oversized at high speeds because flow demand of the transmission is independent of engine speed. The excess flow returns to the tan...

  11. Gingival displacement methods used by dental professionals: A survey

    S V Giridhar Reddy; M.Bharathi; B. Vinod; K Rajeev Kumar Reddy; N Simhachalam Reddy


    Aim: The aim of the present study was to identify the methods used by dental professionals for gingival displacement before making impressions for fixed prostheses. Materials and Methods: A printed questionnaire was distributed to over 600 dentists at a National Dental Conference held in Hyderabad. The questionnaire was designed to know the preferred method of gingival displacement, medicament used, frequency of performing gingival displacement, etc. The results were analyzed and represented ...

  12. Employment protection and the consequences for displaced workers

    Albæk, Karsten; van Audenrode, Marc; Browning, Martin

    We compare the wage and employment consequences of a job displacement in Belgium and Denmark. These two countries both have generous unemployment insurance schemes but job protection laws vary dramatically between the two. Using comparable data we find that the incidence of displacement...... and the consequences for wages are similar in the two countries. The consequences for employment are very different with Danish workers experiencing much less unemployment after a displacement...

  13. Displacement spectra and displacement modification factors, based on records from Greece

    Athanassiadou, C. J.; Karakostas, C. Z.; Margaris, B. N.; Kappos, A. J.


    Elastic and inelastic displacement spectra (for periods up to 4.0 s) are derived, using a representative sample of acceleration records from Greece, carefully selected based on magnitude, distance and peak ground acceleration criteria, and grouped into three ground type categories according to the Eurocode 8 (EC8) provisions. The modification factor for the elastic design spectrum adopted in EC8 for accounting for damping is verified herein and is found to be satisfactory in the short to medi...

  14. Radiofrequency Catheter Ablation Targeting the Vein of Marshall in Difficult Mitral Isthmus Ablation or Pulmonary Vein Isolation.

    Lee, Ji Hyun; Nam, Gi-Byoung; Kim, Minsu; Hwang, You Mi; Hwang, Jongmin; Kim, Jun; Choi, Kee-Joon; Kim, You-Ho


    The ligament of Marshall may hinder the creation of mitral isthmus (MI) block or pulmonary vein (PV) isolation (PVI) in radiofrequency (RF) catheter ablation of atrial fibrillation (AF). We aimed to assess the benefit of RF ablation targeting the vein of Marshall (VOM) in failed cases of MI block or PVI. We reviewed the medical records of patients who underwent RF ablation targeting the VOM after failed MI ablation or left PVI using the conventional method, which included circumferential point-by-point ablation around the PV antrum and carina for PVI, and endocardial MI and epicardial distal coronary sinus (CS) ablation for MI block. The VOM was identified by using selective VOM venography with an external irrigation RF ablation catheter. RF ablation targeting the VOM was performed with RF application at the ostium of the VOM inside the CS or at the endocardial region facing the VOM course. During the set period, CS venography was performed in 42 patients after failure of left PVI (n = 5) or MI block (n = 37). Under CS venography, the VOM was visualized in 22 of 42 patients (MI = 19 and PVI = 3). During selective venography of the VOM, no procedure-related complication was observed. RF application targeting the VOM successfully achieved MI block in 13 patients (68.4%) and PVI in 2 patients (66.7%). Selective VOM venography using an irrigated ablation catheter is feasible and safe. RF ablation targeting the VOM may provide additional benefit in failed cases of MI block or PVI. © 2017 Wiley Periodicals, Inc.

  15. Isothermal Gas assisted displacement of a polystyrene melt

    Eriksson, Torbjörn Gerhard; Rasmussen, Henrik K.


    Isothermal gas displacements of a polystyrene melt (shaped as circular cylinder with a radius of 2.5mm) placed inside a circular steel annulus were performed. A flow valve ensures a constant flow rate and rotational symmetric flow during the displacement. The experiments show an increase in the s......Isothermal gas displacements of a polystyrene melt (shaped as circular cylinder with a radius of 2.5mm) placed inside a circular steel annulus were performed. A flow valve ensures a constant flow rate and rotational symmetric flow during the displacement. The experiments show an increase...

  16. Studying Landslide Displacements in Megamendung (Indonesia Using GPS Survey Method

    Hasanuddin Z. Abidin


    Full Text Available Landslide is one of prominent geohazards that frequently affects Indonesia, especially in the rainy season. It destroys not only environment and property, but usually also causes deaths. Landslide monitoring is therefore very crucial and should be continuously done. One of the methods that can have a contribution in studying landslide phenomena is repeated GPS survey method. This paper presents and discusses the operational performances, constraints and results of GPS surveys conducted in a well known landslide prone area in West Java (Indonesia, namely Megamendung, the hilly region close to Bogor. Three GPS surveys involving 8 GPS points have been conducted, namely on April 2002, May 2003 and May 2004, respectively. The estimated landslide displacements in the area are relatively quite large in the level of a few dm to a few m. Displacements up to about 2-3 m were detected in the April 2002 to May 2003 period, and up to about 3-4 dm in the May 2003 to May 2004 period. In both periods, landslides in general show the northwest direction of displacements. Displacements vary both spatially and temporally. This study also suggested that in order to conclude the existence of real and significant displacements of GPS points, the GPS estimated displacements should be subjected to three types of testing namely: the congruency test on spatial displacements, testing on the agreement between the horizontal distance changes with the predicted direction of landslide displacement, and testing on the consistency of displacement directions on two consecutive periods.

  17. Downward finger displacement distinguishes Parkinson disease dementia from Alzheimer disease.

    Lieberman, Abraham; Deep, Aman; Shi, Jiong; Dhall, Rohit; Shafer, Saulena; Moguel-Cobos, Guillermo; Dhillon, Ravneet; Frames, Christopher W; McCauley, Margaret


    Purpose/Aim of the study: To study finger displacement in patients with Parkinson disease dementia (PDD) and in patients with Alzheimer disease (AD). We examined 56 patients with PDD and 35 with AD. Patients were examined during their regular outpatient clinic visit. Finger displacement was measured by observers not actively involved in the study using a creative grid ruler for all PDD and AD patients. Finger displacement was examined by asking patients to point their index fingers toward the grid ruler with the nails facing upward. Patients were asked to maintain the pointing position for 15 s. After 15 s, patients were asked to close their eyes for another 15 s while maintaining the same position. A positive result was downward index finger displacement of ≥5 cm within the 15-second time window with eyes closed. Of the 56 PDD patients, 53 had bilateral finger displacement of > 5 cm. In comparison, of the 35 AD patients, only 1 patient had minimal displacement. Results of the non-invasive finger displacement test may provide insight, on an outpatient basis, of the integrity of subcortical-cortical circuits. Downward finger displacement, especially bilateral downward displacement, may signal the extensive disruption of subcortical-cortical circuits that occurs in PDD patients.

  18. Transarterial ablation of hepatocellular carcinoma. Status and developments; Transvaskulaere Ablation des hepatozellulaeren Karzinoms. Ist Chemotherapie alles

    Radeleff, B.A.; Stampfl, U.; Sommer, C.M.; Bellemann, N.; Kauczor, H.U. [Universitaetsklinikum Heidelberg, Abt. Diagnostische und Interventionelle Radiologie, Radiologische Klinik, Heidelberg (Germany); Hoffmann, K. [Universitaetsklinikum Heidelberg, Abt. fuer Allgemein-, Viszeral- und Transplantationschirurgie, Chirurgische Klinik, Heidelberg (Germany); Ganten, T.; Ehehalt, R. [Universitaetsklinikum Heidelberg, Medizinische Klinik IV, Gastroenterologie, Infektionskrankheiten, Vergiftungen, Heidelberg (Germany)


    Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and represents the main cause of death among European patients with liver cirrhosis. Only 30-40% of patients diagnosed with HCC are candidates for curative treatment options (e.g. surgical resection, liver transplantation or ablation). The remaining majority of patients must undergo local regional and palliative therapies. Transvascular ablation of HCC takes advantage of the fact that the hypervascularized HCC receives most of its blood supply from the hepatic artery. In this context transvascular ablation describes different therapy regimens which can be assigned to four groups: cTACE (conventional transarterial chemoembolization), bland embolization (transarterial embolization TAE), DEB-TACE (TACE with drug-eluting beads, DEB) and SIRT (selective internal radiation therapy, radioembolization). Conventional TACE is the most common type of transvascular ablation and represents a combination of intra-arterial chemotherapy and embolization with occlusion of the arterial blood supply. However, there is no standardized regimen with respect to the chemotherapeutic drug, the embolic agent, the usage of lipiodol and the interval between the TACE procedures. Even the exact course of a cTACE procedure (order of chemotherapy or embolization) is not standardized. It remains unclear whether or not intra-arterial chemotherapy is definitely required as bland embolization using very small, tightly calibrated spherical particles (without intra-arterial administration of a chemotherapeutic drug) shows tumor necrosis comparable to cTACE. For DEB-TACE microparticles loaded with a chemotherapeutic drug combine the advantages of cTACE and bland embolization. Thereby, a continuing chemotherapeutic effect within the tumor might cause a further increase in intratumoral cytotoxicity and at the same time a decrease in systemic toxicity. (orig.) [German] Das hepatozellulaere Karzinom (HCC) ist weltweit betrachtet das

  19. The Three Gorges: the unexamined toll of development-induced displacement

    Martin Stein


    In China, the context of forced displacement in its broadest sense centres on four issues: (1) coercive displacement for development; (2) political persecution resulting in controlled displacement; (3) massive labour dislocations; and (4) disaster-induced displacement. This article looks at the role of the state in displacement, focusing on the first of these issues: development-induced displacement.

  20. Ablation-cooled material removal with ultrafast bursts of pulses

    Kerse, Can; Kalaycıoğlu, Hamit; Elahi, Parviz; Çetin, Barbaros; Kesim, Denizhan K.; Akçaalan, Önder; Yavaş, Seydi; Aşık, Mehmet D.; Öktem, Bülent; Hoogland, Heinar; Holzwarth, Ronald; Ilday, Fatih Ömer


    The use of femtosecond laser pulses allows precise and thermal-damage-free removal of material (ablation) with wide-ranging scientific, medical and industrial applications. However, its potential is limited by the low speeds at which material can be removed and the complexity of the associated laser technology. The complexity of the laser design arises from the need to overcome the high pulse energy threshold for efficient ablation. However, the use of more powerful lasers to increase the ablation rate results in unwanted effects such as shielding, saturation and collateral damage from heat accumulation at higher laser powers. Here we circumvent this limitation by exploiting ablation cooling, in analogy to a technique routinely used in aerospace engineering. We apply ultrafast successions (bursts) of laser pulses to ablate the target material before the residual heat deposited by previous pulses diffuses away from the processing region. Proof-of-principle experiments on various substrates demonstrate that extremely high repetition rates, which make ablation cooling possible, reduce the laser pulse energies needed for ablation and increase the efficiency of the removal process by an order of magnitude over previously used laser parameters. We also demonstrate the removal of brain tissue at two cubic millimetres per minute and dentine at three cubic millimetres per minute without any thermal damage to the bulk.

  1. Actual role of radiofrequency ablation of liver metastases

    Pereira, Philippe L. [Eberhard-Karls-University of Tuebingen, Department of Diagnostic Radiology, Tuebingen (Germany)


    The liver is, second only to lymph nodes, the most common site for metastatic disease irrespective of the primary tumour. More than 50% of all patients with malignant diseases will develop liver metastases with a significant morbidity and mortality. Although the surgical resection leads to an improved survival in patients with colorectal metastases, only approximately 20% of patients are eligible for surgery. Thermal ablation and especially radiofrequency ablation emerge as an important additional therapy modality for the treatment of liver metastases. RF ablation shows a benefit in life expectancy and may lead in a selected patient group to cure. Percutaneous RF ablation appears safer (versus cryotherapy), easier (versus laser), and more effective (versus ethanol instillation and transarterial chemoembolisation) compared with other minimally invasive procedures. RF ablation can be performed by a percutaneous, laparoscopical or laparotomic approach, and may be potentially combined with chemotherapy and surgery. At present ideal candidates have tumours with a maximum diameter less than 3.5 cm. An untreatable primary tumour or a systemic disease represents contraindications for performing local therapies. Permanent technical improvements of thermal ablation devices and a better integration of thermal ablation in the overall patient care may lead to prognosis improvement in patients with liver metastases. (orig.)

  2. Diagnosing Implosion Velocity and Ablator Dynamics at NIF

    Grim, Gary; Hayes, Anna; Jungman, Jerry; Wilson, Doug; Wilhelmy, Jerry; Bradley, Paul; Rundberg, Bob; Cerjan, Charlie


    An enhanced understanding of the environment in a burning NIF capsule is of interest to both astrophysics and thermonuclear ignition. In this talk we introduce a new diagnostic idea, designed to measure dynamic aspects of the capsule implosion that are not currently accessible. During the burn,the NIF capsule ablator is moving relative to the 14.1 MeV dt neutrons that are traversing the capsule. The resulting neutron-ablator Doppler shift causes a few unique nuclear reactions to become sensitive detectors of the ablator velocity at peak burn time. The ``point-design'' capsule at the NIF will be based on a ^9Be ablator, and the ^9Be(n,p)^9Li reaction has an energy threshold of 14.2 MeV, making it the ideal probe. As discussed in detail below, differences in the ablator velocity lead to significant differences in the rate of ^9Li production. We present techniques for measuring this ^9Li implosion velocity diagnostic at the NIF. The same experimental techniques, measuring neutron reactions on the ablator material, will allow us to determine other important dynamical quantities, such as the areal density and approximate thickness of the ablator at peak burn.

  3. Wavelength scaling of silicon laser ablation in picosecond regime

    Sikora, A.; Grojo, D.; Sentis, M.


    Single pulse laser ablation of silicon has been investigated at 343, 515, and 1030 nm using a laser pulse duration of 50 ps. In this large spectral range, ablation thresholds of silicon vary from 0.01 to 0.83 J/cm2, confirming a strong dependence on the wavelength. By solving the free-carrier density rate equation at threshold conditions, we show that band-to-band linear absorption dominates energy deposition at 343 and 515 nm, whereas at 1030 nm, the energy leading to ablation is primarily absorbed by the generated free-carriers. This allows us to determine the relevant criteria to derive a simple model predicting the wavelength dependence of the ablation threshold in this regime. We obtain an excellent agreement between experimental measurements and calculations by simply considering an averaged energy density required in the absorption depth for surface ablation and accounting for the laser-induced variations of the important thermophysical parameters. On the basis of this analysis, we discuss the optimal wavelength and fluence conditions for maximum removal rate, ablation efficiency, and accuracy. Despite the difference in mechanisms at the different wavelengths, we find that the maximal efficiency remains at around 7 times the ablation threshold fluence for all investigated wavelengths. This work provides guidelines for high-quality and efficient micromachining of silicon in the scarcely explored picosecond regime, while new picosecond sources offer numerous advantages for real throughput industrial applications.

  4. Pacemaker implantation after catheter ablation for atrial fibrillation.

    Deshmukh, Abhishek J; Yao, Xiaoxi; Schilz, Stephanie; Van Houten, Holly; Sangaralingham, Lindsey R; Asirvatham, Samuel J; Friedman, Paul A; Packer, Douglas L; Noseworthy, Peter A


    Sinus node dysfunction requiring pacemaker implantation is commonly associated with atrial fibrillation (AF), but may not be clinically apparent until restoration of sinus rhythm with ablation or cardioversion. We sought to determine frequency, time course, and predictors for pacemaker implantation after catheter ablation, and to compare the overall rates to a matched cardioversion cohort. We conducted a retrospective analysis using a large US commercial insurance database and identified 12,158 AF patients who underwent catheter ablation between January 1, 2005 and December 31, 2012. Over an average of 2.4 years of follow-up, 5.6 % of the patients underwent pacemaker implantation. Using the Cox proportional hazards models, we found that risk of risks of pacemaker implantation was associated with older age (50-64 and ≥65 versus pacemaker implantation between ablation patients and propensity score (PS)-matched cardioversion groups (3.5 versus. 4.1 % at 1 year and 8.8 versus 8.3 % at 5 years). Overall, pacemaker implantation occurs in about 1/28 patients within 1 year of catheter ablation. The overall implantation rate decreased between 2005 and 2012. Furthermore, the risk after ablation is similar to cardioversion, suggesting that patients require pacing due to a common underlying electrophysiologic substrate, rather than the ablation itself.

  5. [Anesthetic consideration in patients undergoing catheter ablation for atrial fibrillation].

    Oda, Toshiyuki; Takahama, Yutaka


    This chapter describes anesthetic consideration in patients undergoing catheter ablation for atrial fibrillation (AF) based on electrophysiologic or pharmacological aspects. In the 2011 guidelines of the Japanese Circulation Society for non-pharmacotherapy of cardiac arrhythmias, catheter ablation is recommended as Class I therapeutic modality for the patients with drug-refractory paroxysmal AF. Catheter ablation of AF is an invasive and long-lasting procedure necessitating sedation during treatment. However, in the most of the patients, sedation or anesthesia is possibly performed by cardiologists using propofol, midazolam or dexmedetomidine. Deep sedation accompanies a high risk of ventilatory or circulatory derangement. Furthermore, life-threatening complications, such as cerebral infarction or cardiac tamponade, can occur during ablation. Patients with AF are increasing in number as a trend in the aging society, resulting in an increase in catheter ablation in high risk patients. To accomplish safe anesthetic management of the patients for catheter ablations, anesthesiologists are required to have fundamental knowledge and skill in the performance of the catheter ablation.

  6. Second generation endometrial ablation techniques: an audit of clinical practice.

    Madhu, Chendrimada K; Nattey, Joseph; Naeem, Tahira


    To audit the practice and effectiveness of second generation endometrial ablation techniques (microwave and thermal balloon ablation). An audit of microwave and balloon endometrial ablation procedures was completed and performed during a 2-year period, in two district hospitals of Calderdale and Huddersfield NHS Trust, UK. Patients were followed up with for a maximum of 1 year postoperatively, or were referred again from their GPs, with symptoms. A questionnaire was also completed to evaluate patient satisfaction. About 136 and 59 women underwent balloon and microwave endometrial ablation, respectively (Total = 195), for heavy periods. By the end of year 1, 16% of patients were amenorrhoeic and 60% had lighter periods. About 15% of women did not have any relief of symptoms and needed a hysterectomy by 3 years. There were no statistically significant differences in the endometrial ablation techniques. There was no significant effect of age, body mass index, utero-cervical length, or the ablation technique on the results or the hysterectomy rates. A satisfaction survey showed that 75% of women felt better after the procedure and would recommend it to a close friend. Second generation ablation techniques are safe and effective methods of treating dysfunctional uterine bleeding, and are easy to use. They have reduced the incidence of hysterectomies and also have financial implications for healthcare providers.

  7. Displacement of the ventricular fold following cordectomy.

    Fukuda, H; Tsuji, D H; Kawasaki, Y; Kawaida, M; Sakou, T


    In order to avoid radiation and its undesirable side effects, we have employed surgical techniques for treatment of early glottic cancer when the lesion is confined to one membranous cord (Fukuda, Saito, Sato, and Kitahara: J. Jpn. Bronchoesophagol. Soc. 30: 7-14, 1979; Fukuda and Saito: Otologica 26: 434-436, 1980; Fukuda, Kawaida, Ohki, Kawasaki, Kita, and Tatehara: J. Jpn. Bronchoesophagaol. Soc. 39: 139-144, 1988). Laser is one of the most popular techniques and it has been accepted as the first choice by many authors (Annyas, Overbeek, Escajadillo, and Hoeksema: Laryngoscope 94: 836-838, 1984; Mcguirt and Koufman: Arch. Otolaryngol. Head Neck Surg. 113: 501-505, 1987; Tsuji, Fukuda, Kawaskai, Kawaida, and Kanzaki: Keio J. Med. 38: 413-418, 1989). However, some cases are difficult to approach by direct laryngoscopy, requiring an external way to expose the lesion. In these cases, cordectomy by laryngofissure is the method of choice, but the function of the glottis could be improved by replacing the excised cord displacing the ventricular fold. This technique, designed by the authors, was carried out in 22 patients and the results from the viewpoint of phonodynamics, voice quality, and cure rate are discussed in this study. The results are encouraging and we believe that this method is a very reasonable alternative to the laser when such equipment is not available. We also believe that late side effects and oncogenic problems associated with radiation are important points to be considered, especially in patients of relatively younger age.

  8. Motional displacements in proteins incorporating dynamical diversity

    Vural, Derya; Smith, Jeremy; Glyde, Henry

    The average mean square displacement (MSD), , of hydrogen H in proteins is measured using incoherent neutron scattering methods. The observed MSD shows a marked increase in magnitude at a temperature TD ~= 240 K. This is widely interpreted as a dynamical transition to large MSDs which make function possible in proteins. However, when the data is interpreted in terms of a single averaged MSD, the extracted depends on the neutron momentum transfer, ℏQ , used in the measurement. We have shown recently that this apparent dependence on Q arises because the dynamical diversity of the H in the protein is neglected[2]. We present models of the dynamical diversity of H in Lysosyme that when used in the analysis of simulated neutron data lead to consistent, Q independent values for the average MSD and for the diversity model.2. D. Vural and L. Hong, J. C. Smith and H. R. Glyde. Phys. Rev. E 91, 052705 (2015). Supported in part by Office of Basic Energy Sciences, USDOE, ER46680.


    Franci Vindišar


    Full Text Available Background. The exact knowledge of the anatomic relations of the juvenile skeleton is of great importance for the determination of the injury and proper treatment. The treatment should be uniform and carried out in one act. Considering this facts the functional results are usually very good and no late sequel are recorded.Methods. In 5-years period 25 children with age 7 to 17 were treated with displaced fracture of ankle. The Salter-Harris classification (SHC was used. Children were classified in two groups. In first group (G-I 11 children were treated with closed reduction. Whole group was classified as type II fractures of SHC. In second group (G-II 14 children were treated operatively. 10 cases were type III, 2 cases were type IV of SHC and 2 were juvenil Tillaux fracture. In follow-up we registered the duration of immobilisation, non-weight bearing period, mobility and residual pain at the end of the treatment.Results. In G-I average non-weight bearing period was 10.4 weeks, in G-II only 7.8 weeks. At the end of the treatment in both groups very good functional results were achieved. There were no complications in operative group (G-II.Conclusions. Children relatively often suffer ankle injuries. With proper diagnosis and early adequate treatment the prognosis is good and no functional sequel were recorded.

  10. Mythic displacement in Nigerian narratives: An introduction

    Ignatius Chukwumah


    Full Text Available Five decades of resorting to humanistic critical procedureshave bequeathed to the Nigerian critical practice the legacy ofexamining and discovering in Nigerian and African narrativesthe historical and social concepts of the time and times theyare presumed to posit. These concepts include colonialism,corruption, war, political instability, and culture conflict. Theseprocedures are undertaken without due regard to seeing the wholeof the literary tradition as a stream out of which narratives emerge.This article, therefore, by way of introduction, seeks to retrieveNigerian narratives from “every author” and humanistic criticalapproach by placing them in a realm where a holistic method suchas Frye’s could be applied. Here, the traverses of the structure ofmythical imagery such as the mythos of crime and punishmentas embodied in these narratives and how this structure wasdisplaced/shrouded from Frye’s first mimetic mode to the last, viathe concept of mythic displacement, will be analysed.

  11. Measurements of Ablation Pressure and Mass Ablation Rate Using a Target Pendulum and a Thin Foil Target at 10 μm Laser Wavelength

    Daido, Hiroyuki; Tateyama, Ryuzi; Ogura, Kazuki; Mima, Kunioki; Nakai, Sadao; Yamanaka, Chiyoe


    The ablation pressure and the mass ablation rate for a 10 μm CO2 laser were measured using two methods: a ballistic target pendulum and shifted X-ray emission images which are equivalent to X-ray back-lighting. The measured ablation pressure was 10 Mbar and the mass ablation rate was 106 g/cm2\\cdotsec at the absorbed laser intensity of 5× 1013 W/cm2. Comparing the ablation mass rate measured by the pendulum with that derived from the penetration depth of the hot electrons using K_α line emission, we could identify the hot electron driven ablation as the dominant process.

  12. MRI evaluation of RF ablation scarring for atrial fibrillation treatment

    Ishihara, Yuri; Nazafat, Reza; Wylie, John V.; Linguraru, Marius G.; Josephson, Mark E.; Howe, Robert D.; Manning, Warren J.; Peters, Dana C.


    This study presents a multi-modality image registration method that evaluates left atrial scarring after radiofrequency (RF) ablation for pulmonary vein (PV) isolation. Our group has recently developed a delayed enhancement magnetic resonance imaging (DE-MRI) method with the potential to visualize and monitor non-invasively post-ablation scarring in the left atrium and the PV ostia. We wished to compare the 3D configuration of scarring in the DE-MRI image and the ablation points recorded by electroanatomical mapping (EAM) system, hypothesizing that scarring detected by DE-MRI overlaps with ablation points recorded by the EAM system used in the procedure. Methods and Results: Three data sets, DE-MRI images and pulmonary vein MR angiography (PV-MRA) images, and EAM data (CARTO-XP, Biosense-Webster, Inc., Diamond Bar, CA) from a patient who underwent PV ablation, were used for the multi-modal image registration. Contrast-enhanced MR imaging was performed 38 days after the ablation procedure. PV-MRA and DE-MRI were fused by intensity-based rigid registration. Scar tissue was extracted from the DE-MRI images using multiple threshold values. EAM data was further fused with segmented PV-MRA by the iterative closest point algorithm (ICP). After registration, the distance from PV-MRA to the scar was 2.6 +/- 2.1 mm, and from ablation points to the surface of the scar was 2.5 +/- 2.3 mm. The fused image demonstrates the 3D relationship between the PV ostia, the scar and the EAM recording of ablation points. Conclusion: Multimodal data fusion indicated that the scar tissue lesion after PV isolation showed good overlap with the ablation points.

  13. The impact of frequency on the performance of microwave ablation.

    Sawicki, James F; Shea, Jacob D; Behdad, Nader; Hagness, Susan C


    The use of higher frequencies in percutaneous microwave ablation (MWA) may offer compelling interstitial antenna design advantages over the 915 MHz and 2.45 GHz frequencies typically employed in current systems. To evaluate the impact of higher frequencies on ablation performance, we conducted a comprehensive computational and experimental study of microwave absorption and tissue heating as a function of frequency. We performed electromagnetic and thermal simulations of MWA in ex vivo and in vivo porcine muscle at discrete frequencies in the 1.9-26 GHz range. Ex vivo ablation experiments were performed in the 1.9-18 GHz range. We tracked the size of the ablation zone across frequency for constant input power and ablation duration. Further, we conducted simulations to investigate antenna feed line heating as a function of frequency, input power, and cable diameter. As the frequency was increased from 1.9 to 26 GHz the resulting ablation zone dimensions decreased in the longitudinal direction while remaining relatively constant in the radial direction; thus at higher frequencies the overall ablation zone was more spherical. However, cable heating at higher frequencies became more problematic for smaller diameter cables at constant input power. Comparably sized ablation zones are achievable well above 1.9 GHz, despite increasingly localised power absorption. Specific absorption rate alone does not accurately predict ablation performance, particularly at higher frequencies where thermal diffusion plays an important role. Cable heating due to ohmic losses at higher frequencies may be controlled through judicious choices of input power and cable diameter.

  14. Laser systems for ablative fractional resurfacing

    Paasch, Uwe; Haedersdal, Merete


    of a variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional...... ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities...... with AFR incorporating our personal experience. AFR is still in the exploratory era, and systematic investigations of clinical outcomes related to various system settings are needed....

  15. Flexible Ablators Char Depths LHMEL Test Results

    White, Susan; Qu, Vince; Fan, Wendy; Stackpoole, Mairead; Thornton, Jeremy


    Char and pyrolysis zone depths give physical evidence of peak temperature reached in depth: The pyrolyzing material acts as a temperature indicator within its characteristic thermal decomposition range. A matrix of novel flexible ablators were laser tested in one component of material screening for NASA Entry, Descent and Landing research for future Mars missions. LHMEL tests were run both on virgin materials, and on previously charred materials for a dual pulse simulation of the heating due to aerocapture followed by atmospheric entry. The test models were machined to expose the cross-sections. Char measurements were made at three locations near the center of the exposed area. Data are presented showing the char depths developed in these flexible materials, grouped by reinforcing fiber and pyrolyzing material type.

  16. Emerging indications of endoscopic radiofrequency ablation

    Becq, Aymeric; Camus, Marine; Rahmi, Gabriel; de Parades, Vincent; Marteau, Philippe


    Introduction Radiofrequency ablation (RFA) is a well-validated treatment of dysplastic Barrett's esophagus. Other indications of endoscopic RFA are under evaluation. Results Four prospective studies (total 69 patients) have shown that RFA achieved complete remission of early esophageal squamous intra-epithelial neoplasia at a rate of 80%, but with a substantial risk of stricture. In the setting of gastric antral vascular ectasia, two prospective monocenter studies, and a retrospective multicenter study, (total 51 patients), suggest that RFA is efficacious in terms of reducing transfusion dependency. In the setting of chronic hemorrhagic radiation proctopathy, a prospective monocenter study and a retrospective multicenter study (total 56 patients) suggest that RFA is an efficient treatment. A retrospective comparative study (64 patients) suggests that RFA improves stents patency in malignant biliary strictures. Conclusions Endoscopic RFA is an upcoming treatment modality in early esophageal squamous intra-epithelial neoplasia, as well as in gastric, rectal, and biliary diseases. PMID:26279839


    B. Ya. Alekseev


    Full Text Available The wide use of current diagnostic techniques, such as ultrasound study, computed tomography, and magnetic resonance imaging, has led to significantly increased detection rates for disease in its early stages. This gave rise to a change in the standards for the treatment of locally advanced renal cell carcinoma (RCC. Laparoscopic nephrectomy (LN has recently become the standard treatment of locally advanced RCC in the clinics having much experience with laparoscopic surgery. The chief drawback of LN is difficulties in maintaining intraoperative hemostasis and a need for creating renal tissue ischemia. The paper gives the intermediate results of application of the new procedure of LN using radiofrequency thermal ablation in patients with non-ischemic early-stage RCC.

  18. Nanosecond laser ablation and deposition of silicon

    Siew, Wee Ong; Tou, Teck Yong [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor (Malaysia); Yap, Seong Shan; Reenaas, Turid Worren [Norwegian University of Science and Technology, Department of Physics, Trondheim (Norway); Ladam, Cecile; Dahl, Oeystein [SINTEF Materials and Chemistry, Trondheim (Norway)


    Nanosecond-pulsed KrF (248 nm, 25 ns) and Nd:YAG (1064 nm, 532 nm, 355 nm, 5 ns) lasers were used to ablate a polycrystalline Si target in a background pressure of <10{sup -4} Pa. Si films were deposited on Si and GaAs substrates at room temperature. The surface morphology of the films was characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Round droplets from 20 nm to 5 {mu}m were detected on the deposited films. Raman Spectroscopy indicated that the micron-sized droplets were crystalline and the films were amorphous. The dependence of the properties of the films on laser wavelengths and fluence is discussed. (orig.)

  19. Radiofrequency interstitial tumor ablation: dry electrode.

    Johnson, D Brooke; Cadeddu, Jeffrey A


    With the shift in the treatment of small renal tumors from radical extirpative surgery to nephron-sparing approaches, dry-electrode radiofrequency ablation (RFA) has emerged as one potential modality. This application of RF energy leads to the production of heat within the treatment zone secondary to the native impedance of living tissue. Animal studies and human clinical series have demonstrated that RFA can create controlled, targeted, reproducible, and lethal lesions. Most clinical series have reported promising results, although some authors question the totality of tumor destruction by RFA. With time, the efficacy of RFA, as measured by patient survival, will be determined. Once this is known, RFA may be compared with other therapeutic modalities for small renal tumors to determine its place.

  20. Radiofrequency ablation of a misdiagnosed Brodie's abscess.

    Chan, Rs; Abdullah, Bjj; Aik, S; Tok, Ch


    Radiofrequency ablation (RFA) therapy is recognised as a safe and effective treatment option for osteoid osteoma. This case report describes a 27-year-old man who underwent computed tomography (CT)-guided percutaneous RFA for a femoral osteoid osteoma, which was diagnosed based on his clinical presentation and CT findings. The patient developed worsening symptoms complicated by osteomyelitis after the procedure. His clinical progression and subsequent MRI findings had led to a revised diagnosis of a Brodie's abscess, which was further supported by the eventual resolution of his symptoms following a combination of antibiotics treatment and surgical irrigations. This case report illustrates the unusual MRI features of osteomyelitis mimicking soft tissue tumours following RFA of a misdiagnosed Brodie's abscess and highlights the importance of a confirmatory histopathological diagnosis for an osteoid osteoma prior to treatment.

  1. Deflection of uncooperative targets using laser ablation

    Thiry, Nicolas; Vasile, Massimiliano


    Owing to their ability to move a target in space without requiring propellant, laser-based deflection methods have gained attention among the research community in the recent years. With laser ablation, the vaporized material is used to push the target itself allowing for a significant reduction in the mass requirement for a space mission. Specifically, this paper addresses two important issues which are thought to limit seriously the potential efficiency of a laser-deflection method: the impact of the tumbling motion of the target as well as the impact of the finite thickness of the material ablated in the case of a space debris. In this paper, we developed a steady-state analytical model based on energetic considerations in order to predict the efficiency range theoretically allowed by a laser deflection system in absence of the two aforementioned issues. A numerical model was then implemented to solve the transient heat equation in presence of vaporization and melting and account for the tumbling rate of the target. This model was also translated to the case where the target is a space debris by considering material properties of an aluminium 6061-T6 alloy and adapting at every time-step the size of the computational domain along with the recession speed of the interface in order to account for the finite thickness of the debris component. The comparison between the numerical results and the analytical predictions allow us to draw interesting conclusions regarding the momentum coupling achievable by a given laser deflection system both for asteroids and space debris in function of the flux, the rotation rate of the target and its material properties. In the last section of this paper, we show how a reasonably small spacecraft could deflect a 56m asteroid with a laser system requiring less than 5kW of input power.

  2. Ablation dynamics in laser sclerotomy ab externo

    Brinkmann, Ralf; Droege, Gerit; Mohrenstecher, Dirk; Scheu, M.; Birngruber, Reginald


    Laser sclerostomy ab externo with flashlamp excited mid-IR laser systems emitting in the 2-3 micrometer spectral range is in phase II clinical trials. Although acutely high success rates were achieved, the restenosis rate after several months is about 40%. Laser pulses of several hundreds of microseconds, known to induce thermo-mechanical explosive evaporation were used for this procedure. We investigated the ablation dynamics in tissue and the cavitation bubble dynamics in water by means of an Er:YAG laser system to estimate the extent of mechanical damage zones in the sclera and in the anterior chamber, which may contribute to the clinical failure. We found substantial mechanical tissue deformation during the ablation process caused by the cavitation effects. Stress waves up to several bar generated by explosive evaporization were measured. The fast mechanical stretching and collapsing of the scleral tissue induced by cavitation resulted in tissue dissection as could be proved by flash photography and histology. The observed high restenosis might be a result of a subsequent enhanced wound healing process. Early fistula occlusions due to iris adherences, observed in about 20% of the clinical cases may be attributed to intraocular trauma induced by vapor bubble expansion through the anterior chamber after scleral perforation. An automatic feedback system minimizing adverse effects by steering and terminating the laser process during scleral fistulization is demonstrated. Moreover, a new approach in laser sclerostomy ab externo is presented using a cw-IR laser diode system emitting at the 1.94 micrometer mid-IR water absorption peak. This system was used in vitro and showed smaller damage zones compared to the pulsed laser radiation.

  3. Laparoscopic radiofrequency ablation of neuroendocrine liver metastases.

    Berber, Eren; Flesher, Nora; Siperstein, Allan E


    We previously reported on the safety and efficacy of laparoscopic radiofrequency thermal ablation (RFA) for treating hepatic neuroendocrine metastases. The aim of this study is to report our 5-year RFA experience in the treatment of these challenging group of patients. Of the 222 patients with 803 liver primary and secondary tumors undergoing laparoscopic RFA between January 1996 and August 2001, a total of 34 patients with 234 tumors had neuroendocrine liver metastases. There were 25 men and 9 women with a mean +/- SEM age of 52 +/- 2 years who underwent 42 ablations. Primary tumor types included carcinoid tumor in 18 patients, medullary thyroid cancer in 7, secreting islet cell tumor in 5, and nonsecreting islet cell tumor in 4. There was no mortality, and the morbidity was 5%. The mean hospital stay was 1.1 days. Symptoms were ameliorated in 95%, with significant or complete symptom control in 80% of the patients for a mean of 10+ months (range 6-24 months). All patients were followed for a mean +/- SEM of 1.6 +/- 0.2 years (range 1.0-5.4 years). During this period new liver lesions developed in 28% of patients, new extrahepatic disease in 25%, and local liver recurrence in 13%; existing liver lesions progressed in 13%. Overall 41% of patients showed no progression of their cancer. Nine patients (27%) died. Mean +/- SEM survivals after diagnosis of primary disease, detection of liver metastases, and performance of RFA were 5.5 +/- 0.8 years, 3.0 +/- 0.3 years, and 1.6 +/- 0.2 years, respectively. Sixty-five percent of the patients demonstrated a partial or significant decrease in their tumor markers during follow-up. In conclusion, RFA provides excellent local tumor control with overnight hospitalization and low morbidity in the treatment of liver metastases from neuroendocrine tumors. It is a useful modality in the management of these challenging group of patients.

  4. Enhanced coupling of optical energy during liquid-confined metal ablation

    Kang, Hyun Wook, E-mail: [Department of Biomedical Engineering, Pukyong National University, Busan, South Korea and Center for Marine-integrated Biomedical Technology (MIBT), Pukyong National University, Busan (Korea, Republic of); Welch, Ashley J. [Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas, 78712 (United States)


    Liquid-confined laser ablation was investigated with various metals of indium, aluminum, and nickel. Ablation threshold and rate were characterized in terms of surface deformation, transient acoustic responses, and plasma emissions. The surface condition affected the degree of ablation dynamics due to variations in reflectance. The liquid confinement yielded up to an order of larger ablation crater along with stronger acoustic transients than dry ablation. Enhanced ablation performance resulted possibly from effective coupling of optical energy at the interface during explosive vaporization, plasma confinement, and cavitation. The deposition of a liquid layer can induce more efficient ablation for laser metal processing.

  5. Micrometeorological processes driving snow ablation in an Alpine catchment

    R. Mott


    Full Text Available Mountain snow covers typically become patchy over the course of a melting season. The snow pattern during melt is mainly governed by the end of winter snow depth distribution and the local energy balance. The objective of this study is to investigate micro-meteorological processes driving snow ablation in an Alpine catchment. For this purpose we combine a meteorological boundary-layer model (Advanced Regional Prediction System with a fully distributed energy balance model (Alpine3D. Turbulent fluxes above melting snow are further investigated by using data from eddy-correlation systems. We compare modeled snow ablation to measured ablation rates as obtained from a series of Terrestrial Laser Scanning campaigns covering a complete ablation season. The measured ablation rates indicate that the advection of sensible heat causes locally increased ablation rates at the upwind edges of the snow patches. The effect, however, appears to be active over rather short distances of about 4–6 m. Measurements suggest that mean wind velocities of about 5 m s−1 are required for advective heat transport to increase snow ablation over a long fetch distance of about 20 m. Neglecting this effect, the model is able to capture the mean ablation rates for early ablation periods but strongly overestimates snow ablation once the fraction of snow coverage is below a critical value of approximately 0.6. While radiation dominates snow ablation early in the season, the turbulent flux contribution becomes important late in the season. Simulation results indicate that the air temperatures appear to overestimate the local air temperature above snow patches once the snow coverage is low. Measured turbulent fluxes support these findings by suggesting a stable internal boundary layer close to the snow surface causing a strong decrease of the sensible heat flux towards the snow cover. Thus, the existence of a stable internal boundary layer above a patchy snow cover

  6. Alternative High Performance Polymers for Ablative Thermal Protection Systems

    Boghozian, Tane; Stackpoole, Mairead; Gonzales, Greg


    Ablative thermal protection systems are commonly used as protection from the intense heat during re-entry of a space vehicle and have been used successfully on many missions including Stardust and Mars Science Laboratory both of which used PICA - a phenolic based ablator. Historically, phenolic resin has served as the ablative polymer for many TPS systems. However, it has limitations in both processing and properties such as char yield, glass transition temperature and char stability. Therefore alternative high performance polymers are being considered including cyanate ester resin, polyimide, and polybenzoxazine. Thermal and mechanical properties of these resin systems were characterized and compared with phenolic resin.

  7. Oncogenesis: An "Off-Target" Effect of Radiofrequency Ablation.

    Rozenblum, Nir; Zeira, Evelyne; Scaiewicz, Viviana; Bulvik, Baruch; Gourevitch, Svetlana; Yotvat, Hagit; Galun, Eithan; Goldberg, S Nahum


    To compare hepatocellular carcinoma (HCC) development after radiofrequency (RF) ablation, partial surgical hepatectomy, and a sham operation and to inhibit HCC recurrence after RF ablation in a mouse model of spontaneously forming HCC in the setting of chronic inflammation (ie, the MDR2 knockout model). Animal experiments were performed according to an approved animal care committee protocol. The authors compared the survival of MDR2 knockout mice (an inflammation-induced HCC model) that underwent RF ablation, 35% partial hepatectomy (ie, left lobectomy), or a sham operation (controls) by using Kaplan-Meier survival curve analysis. Tumor load and tumor frequency in mice that underwent sham operation were further compared with those of mice treated with RF ablation at 1 month after therapy by using a two-tailed Student t test. Liver slices from mice treated with RF ablation were stained for α-smooth muscle actin and Ki-67 to establish the role of liver regeneration in the tumorigenic effect of RF ablation. Finally, tumor load and tumor incidence were evaluated in mice treated with a c-met inhibitor after RF ablation by using the Mann-Whitney U test. Ablation of 3.5% ± 0.02 of the MDR2 knockout mice liver induced increased tumor load (P = .007) and reduced survival (P = .03) in comparison to that of controls, with no significant difference to the 10-fold volume removal of partial hepatectomy. Seven days after RF treatment, the border zone of the coagulation zone was surrounded by α-smooth muscle actin-positive activated myofibroblasts. A significant elevation of hepatocyte proliferation was also seen 7 days after RF ablation in the distant liver (ablated lobe: P = .003; untreated lobe: P = .02). A c-met inhibitor significantly attenuated HCC development in MDR2 knockout mice treated with RF ablation (P = .001). Liver regeneration induced by RF ablation facilitates c-met/hepatocyte growth factor axis-dependent HCC tumor formation after treatment in the MDR2

  8. Analysis of illicit drugs by direct ablation of solid samples.

    Bermúdez, Celina; Cabezas, Carlos; Mata, Santiago; Berdakin, Matias; Tejedor, Jesús M; Alonso, José L


    Analysis of illicit drugs arises as an important field of work given the high social impacts presented by drugs in the modern society. Direct laser ablation of solid compounds allows their analysis without sampling or preparation procedures. For that purpose, an experimental set-up that combines laser ablation with time-of- flight mass spectrometry has been constructed very recently to perform studies on the mass spectra of such drugs as 3,4-methylenedioxy-N-methylamphetamine, commonly known as MDMA or ecstasy. Analysis of the observed fragmentation pattern in mass spectra may elucidate the ablation-induced photofragmentation phenomena produced, which differ from those previously observed with conventional ionization methods.

  9. Ablative Thermal Response Analysis Using the Finite Element Method

    Dec John A.; Braun, Robert D.


    A review of the classic techniques used to solve ablative thermal response problems is presented. The advantages and disadvantages of both the finite element and finite difference methods are described. As a first step in developing a three dimensional finite element based ablative thermal response capability, a one dimensional computer tool has been developed. The finite element method is used to discretize the governing differential equations and Galerkin's method of weighted residuals is used to derive the element equations. A code to code comparison between the current 1-D tool and the 1-D Fully Implicit Ablation and Thermal Response Program (FIAT) has been performed.

  10. Radiofrequency Ablation for Iatrogenic Thyroid Artery Pseudoaneurysm: Initial Experience.

    Jun, Ye Kyeong; Jung, So Lyung; Byun, Ho Kyun; Baek, Jung Hwan; Sung, Jin Yong; Sim, Jung Suk


    Eight iatrogenic thyroid pseudoaneurysms (ITPAs) after thyroid biopsy are reported. The mean ITPA diameter was 7.2 mm (range 4 to 12 mm). Ultrasound (US)-guided compression was initially performed at the neck of the ITPA in all cases. Among them, 4 ITPAs persisted (50%) in which radiofrequency (RF) ablation was performed. Mean RF ablation time and power were 13.5 seconds (range 5 to 24 seconds) and 20 W (range 10 to 50 W), respectively. All 4 cases were treated with RF ablation without any complications.

  11. Effects of Confined Laser Ablation on Laser Plasma Propulsion

    ZHENG Zhi-Yuan; ZHANG Jie; LU Xin; HAO Zuo-Qiang; XU Miao-Hua; WANG Zhao-Hua; WEI Zhi-Yi


    @@ We investigate the effects of confined laser ablation on laser plasma propulsion. Compared with planar ablation,the cavity ablation provides an effective way to obtain a large target momentum and a high coupling coefficient.When laser pukes are focused into a cavity with 1 mm diameter and 2mm depth, a high coupling coefficient is obtained. By using a glass layer to cover the cavity, the coupling coefficient is enhanced by 10 times. Meanwhile,it is found that with the increase of the target surface size, the target momentum presents a linear increase.

  12. Ablation response testing of simulated radioisotope power supplies

    Lutz, Steven A.; Chan, Chris C.


    Results of an experimental program to assess the aerothermal ablation response of simulated radioisotope power supplies are presented. Full-scale general purpose heat source, graphite impact shell, and lightweight radioisotope heater unit test articles are all tested without nuclear fuel in simulated reentry environments. Convective stagnation heating, stagnation pressure, stagnation surface temperature, surface recession profile, and weight loss measurements are obtained for diffusion-limited and sublimation ablation conditions. The recession profile and weight loss measurements show an effect of surface features on the stagnation face. The surface features alter the local heating which in turn affects the local ablation.

  13. Laser Ablation for Cancer: Past, Present and Future

    Schena, Emiliano; Saccomandi, Paola; Fong, Yuman


    Laser ablation (LA) is gaining acceptance for the treatment of tumors as an alternative to surgical resection. This paper reviews the use of lasers for ablative and surgical applications. Also reviewed are solutions aimed at improving LA outcomes: hyperthermal treatment planning tools and thermometric techniques during LA, used to guide the surgeon in the choice and adjustment of the optimal laser settings, and the potential use of nanoparticles to allow biologic selectivity of ablative treatments. Promising technical solutions and a better knowledge of laser-tissue interaction should allow LA to be used in a safe and effective manner as a cancer treatment. PMID:28613248

  14. Meta-analysis of bipolar radiofrequency endometrial ablation versus thermal balloon endometrial ablation for the treatment of heavy menstrual bleeding.

    Zhai, Yan; Zhang, Zihan; Wang, Wei; Zheng, Tingping; Zhang, Huili


    Heavy menstrual bleeding is a common problem that can severely affect quality of life. To compare bipolar radiofrequency endometrial ablation and thermal balloon ablation for heavy menstrual bleeding in terms of efficacy and health-related quality of life (HRQoL). Online registries were systematically searched using relevant terms without language restriction from inception to November 24, 2016. Randomized control trials or cohort studies of women with heavy menstrual bleeding comparing the efficacy of two treatments were eligible. Data were extracted. Results were expressed as risk ratios (RRs) or weighted mean differences (WMDs) with 95% confidence intervals (CIs). Six studies involving 901 patients were included. Amenorrhea rate at 12 months was significantly higher after bipolar radiofrequency endometrial ablation than after thermal balloon ablation (RR 2.73, 95% CI 2.00-3.73). However, no difference at 12 months was noted for dysmenorrhea (RR 1.04, 95% CI 0.68-1.58) or treatment failure (RR 0.78, 95% CI 0.38-1.60). The only significant difference for HRQoL outcomes was for change in SAQ pleasure score (12 months: WMD -3.51, 95% CI -5.42 to -1.60). Bipolar radiofrequency endometrial ablation and thermal balloon ablation reduce menstrual loss and improve quality of life. However, bipolar radiofrequency endometrial ablation is more effective in terms of amenorrhea rate and SAQ pleasure. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  15. Percutaneous radiofrequency thermal ablation of lung VX2 tumors in a rabbit model: evaluation with helical CT findings for the complete and partal ablation

    Jin, Gong Yong; Han, Young Min; Lim, Yeong Su; Jang, Kyu Yun; Lee, Sang Yong; Chung, Gyung Ho [School of Medicine, Chonbuk National Univ., Chonju (Korea, Republic of)


    To evaluate the radiologic findings for complete and partial ablation after percutaneous CT-guided transthoracic radiofrequency ablation (RFA) of lung VX2 tumor implanted in rabbits. Thirteen rabbits with successfully implanted lung VX2 were used. Three rabbits as controls did not receive RFA while the other ten rabbits underwent RFA; 5 complete and 5 partial. RFA was performed using an internally cooled, 17-gauge electrode (Radionics, Burlington, MA) with a 1-cm active tip under CT guidance. Postprocedural CT was performed within 3 days, and we analyzed the ablated size, enhancement pattern, shape, margin, and complications of the complete and partial ablation groups. Rabbits were sacrificed after postprocedural CT with an overdose of ketamine, and pathologic findings of the ablated groups were compared with those of the control group. The size of the ablated lesions and the enhancement pattern differed between the completely and partially ablated groups on chest CT. The size of the ablated lesions was increased by 47.1% in the completely ablated group and by 2.1% in the partially ablated group. In the completely ablated group, VX2 tumor showed absolutely no enhancement, whereas only ablated pulmonary parenchyma outside VX2 showed mild enhancement on enhanced CT. In the partial ablated group, a part of VX2 became strongly enhanced on enhanced CT. On microscopic examination, the completely ablated group demonstrated that a viable tumor cell was not visible. In the partially ablated group, however, a viable tumor cell within the surrounding fibrous capsule on the peripheral area of the VX2 was observed. The important CT findings for evaluation of complete and partial RFA are the ablated size and enhancement pattern of the ablated lesion.

  16. Uniform stability of displacement coupled second-order equations

    Abdelaziz Soufyane


    Full Text Available We prove that the uniform stability of semigroups associated to displacement coupled dissipator systems is equivalent to the uniform stability of velocity coupled dissipator systems. Using this equivalence, we give sufficient conditions for obtaining uniform stability and exact controllability of displacement coupled dissipator systems.

  17. Simple and economical capacitive displacement system for UHV operation.

    Chow, R; Tiller, W A


    A parallel plate capacitor was assembled as a displacement transducer for operation in an UHV environment. The capacitive displacement system was linear over a 2.5 mum range with a resolution of 0.051 mum. Components in the electric circuit were common laboratory instruments.

  18. Isothermal Gas assisted displacement of a polystyrene melt

    Eriksson, Torbjörn Gerhard; Rasmussen, Henrik K.


    Isothermal gas displacements of a polystyrene melt (shaped as circular cylinder with a radius of 2.5mm) placed inside a circular steel annulus were performed. A flow valve ensures a constant flow rate and rotational symmetric flow during the displacement. The experiments show an increase in the s...

  19. Traumatisk diafragmaruptur med displacering af leveren til thorax

    Hornstrup, L.; Burcharth, F.


    We report a case of a traumatic diaphragmatic rupture with the liver displaced to the right hemithorax. MR diagnosed the rupture and the displacement of the liver. The patient was operated on and the total right diaphragmatic rupture was reconstructed by suturing. Traumatic diaphragmatic rupture ...

  20. Study on the applicability of the desk displacement ventilation concept

    Loomans, Marcel G.L.C.


    This paper summarizes an experimental and numerical study into a ventilation concept that combines displacement ventilation with task conditioning, the so-called desk displacement ventilation (DDV) concept. The study uses steady-state and transient results to discuss the applicability of the DDV con

  1. Displacement Ventilation in a Room with Low-Level Diffusers

    Nielsen, Peter V.

    Ventilation systems with vertical displacement flow have been used in industrial areas with high thermal loads for many years. Quite resently the vertical displacement flow systems have grown popular as comfort ventilation in rooms with thermal loads e.g. offices....

  2. Laser phase-detector and counter for fine displacement measurement

    Row, R. T.; Wang, C. P.

    A simple technique for the measurement of fine displacement has been developed. With use of an HeNe laser, an optical phase-detector, and counter, a displacement accuracy of 300 nm has been demonstrated over a range of 2 cm.

  3. Displacement, Outplacement, or Inplacement? Options for Business and Industry.

    Wiltzius, Thomas J.

    This report considers the differences among displacement, outplacement, and inplacement and looks at the risks, benefits, and costs of each. Displacement is defined as the termination of employment with little attention given to corporate or individual needs. Outplacement is defined as the pre-planned management of employee termination, addressing…

  4. Single Parent or Displaced Homemaker Program Management Guide.

    Utah State Office of Education, Salt Lake City. Div. of Vocational Education.

    This guide is designed to provide vocational education, single parent/displaced homemaker program directors, and other interested persons with information to help them support, establish, and conduct programs for single parents or displaced homemakers in the nine vocational education planning regions of Utah. It includes definitions and staff…

  5. 24 CFR 886.338 - Displacement, relocation, and acquisition.


    ... regulations at 49 CFR part 24. A “displaced person” shall be advised of his or her rights under the Fair... persons. A “displaced person” (defined in paragraph (g) of this section) must be provided relocation... the requirements described in 49 CFR part 24, subpart B. (e) Appeals. A person who disagrees with...

  6. Displacement and Force Measurements with Quadrant Photodetector in Optical Tweezers

    郭红莲; 刘春香; 李兆霖; 段建发; 韩学海; 程丙英; 张道中


    A technique of displacement and force measurements with a photodiode quadrant detector in an optical tweezers system is presented. The stiffness of optical trap is calibrated and the leukemia cell membrane tension is measured.The results show that the optical tweezers combined with the quadrant detector is a very useful tool for detecting the displacement and force with a millisecond-order response.

  7. Forced displacement: a development issue with humanitarian elements

    Niels Harild


    Work on conflict-induced forced displacement is at a crucial moment, at a tipping point. Now is the time to consolidate the shift towards full global recognition that the challenge of forced displacement is an integral part of the development agenda too.

  8. 24 CFR 236.1001 - Displacement, relocation, and acquisition.


    ... reasonable steps to minimize the displacement of persons (households, businesses, nonprofit organizations... temporarily to permit rehabilitation or other work for the assisted project. Such tenants must be provided: (1... shall maintain data on the race, ethnic, gender, and disability status of displaced persons....

  9. A Reference Optical System of Laser Doppler Longitudinal Displacement Measurement

    张存满; 赵洋; 李达成


    In this paper, a new reference optical system is put forward to achieve longitudinal displacement measurement. An optical grating is used for frequency mixing and getting high SNR signals in the measurement. Conditions and methods for getting Doppler beat signals are presented.The experiments indicate that this optical syetem can be used to measure the longitudinal displacement with high accuracy.

  10. Retention of Displaced Students after Hurricanes Katrina and Rita

    Coco, Joshua Christian


    The purpose of the study was to investigate the strategies that university leaders implemented to improve retention of displaced students in the aftermaths of Hurricanes Katrina and Rita. The universities that participated in this study admitted displaced students after Hurricanes Katrina and Rita. This study utilized a qualitative…

  11. Hyoid Displacement in Post-Treatment Cancer Patients: Preliminary Findings

    Zu, Yihe; Yang, Zhenyu; Perlman, Adrienne L.


    Purpose: Dysphagia after head and neck cancer treatment is a health care issue; in some cases, the cause of death is not cancer but, rather, the passage of food or liquid into the lungs. Hyoid displacement is known to be important to safe swallowing function. The purpose of this study was to evaluate hyoid displacement after cancer treatment.…

  12. Scaling of interface displacement in a microfluidic comparator

    Vanapalli, S.A.; Ende, van den D.; Duits, M.H.G.; Mugele, F.


    The authors quantify both experimentally and theoretically the scaling behavior between interface displacement and excess pressure drop in a microfluidic comparator. Unlike previous studies, the authors measure the interface displacement in the outlet channel of the comparator that yields a unique p

  13. The effect of bone displacement operations on facial soft tissues.

    Habib, Ali; Hisham, Ahmed


    A novel biomechanical model for face soft tissue (skin, mucosa, and muscles) is introduced to investigate the effect of mandible and chin bone displacement on the overall appearance of the patient's face. Nonlinear FE analysis is applied to the model and the results obtained are used to help surgeons to decide the amount of displacement required.

  14. The use of crosshead displacement in determining fracture parameters

    Walters, C.L.; Voormeeren, L.O.; Janssen, M.


    In determining the fracture toughness of a test specimen, standards currently require either locally-measured load-line displacements or clip gage displacements. In order to measure these parameters, secondary sensors generally need to be installed and calibrated, which often comes at a higher cost.

  15. Displacement, Outplacement, or Inplacement? Options for Business and Industry.

    Wiltzius, Thomas J.

    This report considers the differences among displacement, outplacement, and inplacement and looks at the risks, benefits, and costs of each. Displacement is defined as the termination of employment with little attention given to corporate or individual needs. Outplacement is defined as the pre-planned management of employee termination, addressing…

  16. Fiber-coupled displacement interferometry without periodic nonlinearity

    Ellis, J.D.; Meskers, A.J.H.; Spronck, J.W.; Munnig Schmidt, R.H.


    Displacement interferometry is widely used for accurately characterizing nanometer and subnanometer displacements in many applications. In many modern systems, fiber delivery is desired to limit optical alignment and remove heat sources from the system, but fiber delivery can exacerbate common inter

  17. Measurements of vertical displacements Apollo bridge in Bratislava

    Vlastimil Staněk


    Full Text Available Apollo bridge across the Danube river in Bratislava - description of construction parts. Reference network and long-termmeasurements of displacements. Measurements of vertical displacements of bridge pillars using levelling instruments DiNi 12and Ni 007 and stability testing of the reference points.

  18. Forced displacement: a development issue with humanitarian elements

    Niels Harild


    Full Text Available Work on conflict-induced forced displacement is at a crucial moment, at a tipping point. Now is the time to consolidate the shift towards full global recognition that the challenge of forced displacement is an integral part of the development agenda too.

  19. Incidence and clinical predictors of subsequent atrial fibrillation requiring additional ablation after cavotricuspid isthmus ablation for typical atrial flutter.

    De Bortoli, Alessandro; Shi, Li-Bin; Ohm, Ole-Jørgen; Hoff, Per Ivar; Schuster, Peter; Solheim, Eivind; Chen, Jian


    We sought to investigate the incidence of atrial fibrillation after catheter ablation for typical atrial flutter and to determine the predictors for symptomatic atrial fibrillation that required a further additional dedicated ablation procedure. 127 patients underwent elective cavotricuspid isthmus ablation with the indication of symptomatic, typical atrial flutter. The occurrence of atrial flutter, atrial fibrillation, cerebrovascular events and the need for additional ablation procedures for symptomatic atrial fibrillation was assessed during long-term follow-up. The majority of patients (70%) manifested atrial fibrillation during a follow-up period of 68 ± 24 months, and a significant proportion (42%) underwent one or multiple atrial fibrillation ablation procedures after an average of 26 months from the index procedure. Recurrence of typical atrial flutter was rare. Ten patients (8%) suffered cerebrovascular events. Earlier documentation of atrial fibrillation (OR 3.53), previous use of flecainide (OR 3.33) and left atrial diameter (OR 2.96) independently predicted occurrence of atrial fibrillation during the follow-up. A combination of pre- and intra-procedural documentation of atrial fibrillation (OR 3.81) and previous use of flecainide (OR 2.43) independently predicted additional atrial fibrillation ablation. Atrial fibrillation occurred in the majority of patients after ablation for typical atrial flutter and 42% of them required an additional dedicated ablation procedure. Pre- and intraprocedural documentation of atrial fibrillation together with previous use of flecainide independently predicted atrial fibrillation occurrence and a need for additional ablation. Anticoagulation treatment should be continued in high-risk patients in spite of clinical disappearance of atrial flutter.

  20. [Vestibularly displaced flap with bone augmentation].

    Bakalian, V L


    The aim of this study is to achieve esthetic gingival contours with the help of less traumatic mucogingival surgeries. 9 Patients were operated with horizontal deficiencies in 9 edentulous sites, planned to be restored with fixed partial dentures. In all cases there was lack of keratinized tissues. Temporary bridges were fabricated to all patients. Before surgery the bridges were removed and the abutment teeth were additionally cleaned with ultrasonic device. A horizontal incision was made from lingual (palatal) side between the abutment teeth, which was connected with two vertical releasing incisions to the mucogingival junction from the vestibular side. The horizontal incision was made on a distance 6-10 mm from the crest of the alveolar ridge. A partial thickness flap in the beginning 3-5 mm, then a full thickness flap up to the mucogingival junction, then a partial thickness flap was made. The flap was mobilized and displaced vestibularly. In the apical part the cortical bone was perforated, graft material was put and the flap was sutured. In all 9 cases the horizontal defect was partially or fully eliminated. The width of the keratinized tissues was also augmented in all cases. The postoperative healing was without complications, discomfort and painless. The donor sites also healed without complications. The application of Solcoseryl Dental Adhesive Paste 3 times a day for 7-10 days helped for painless healing of the donor site. The offered method of soft tissue and bone augmentation is effective in the treatment of horizontal defects of edentulous alveolar ridges of not big sizes. It makes possible to achieve esthetic results without traumatizing an additional donor-site.

  1. Displacement ventilation and passive cooling strategies

    Carew, P.; Bekker, B. [PJCarew Consulting, Cape Town (South Africa)


    Displacement ventilation (DV) is widely used a passive cooling strategy because it requires less air supply for cooling compared to conventional mixing ventilation (MV). DV introduces air at low level and low velocity, and at high supply air temperature, usually around 18 degrees C. The slightly cooler air runs along the floor of a room until it reaches a heat load. The heat load induces a plume of warmer air that rises due to lower density. This induces stratification in room temperature with the occupied area of the room. The air near the ceiling is continually exhausted to prevent a build up of warm air into the occupied zone. This paper demonstrated the impacts of using DV in comparison to MV on the peak capacity, size and humidity levels associated with various passive cooling strategies, informed by the ASHRAE DV guidelines. A generic office building in Johannesburg, South Africa, was used as a model. The paper illustrated the extent to which DV can be used as a passive cooling strategy in spaces that were previously considered as having too high a heat load when calculated using MV system guidelines. A comparison of DV and MV also highlighted the risk of over-design when conventional MV guidelines are used to design cooling sources for DV applications. The DV was shown to significantly lower the amount of supply air needed to serve a room's heat load when compared to MV at the same temperatures. This reduction in air supply impacts the feasibility of using passive cooling strategies in evaporative cooling, 2-stage evaporative cooling, thermal storage and air to ground heat exchangers. However, passive cooling strategies are unlikely to be widely implemented until design guidelines are created by organizations such as ASHRAE. 8 refs., 2 tabs., 15 figs.

  2. Surgical treatment of displaced acetabular fractures

    Milenković Saša


    Full Text Available Introduction. Acetabular fractures are severe injuries, generally caused by high-energy trauma, most frequently from traffic accidents or falls from heights. Fractures of the extremities, head injuries, chest, abdomen and pelvic ring injuries are most commonly associated injuries. Objective. The purpose of this study was to evaluate the results of open reduction and internal fixation of acetabular fractures. The open anatomical reduction of the articular surface combined with a rigid internal fixation and early mobilisation have become the standard treatment of these injuries. Methods. We conducted a retrospective analysis of 22 patients of average age 43.13 years. The patients were treated by open reduction and internal fixation at the Orthopaedic Clinic of Niš from 2005-2009. The follow-up was 12 to 60 months, with the average of 21.18 months after surgery. Results. All injured patients were operated on between 4 and 11 days (5.7 days on the average. According to the classification by Judet and Letournel, 15 (68.18% patients had an elementary acetabular fracture, whereas 7 (31.82% patients had associated fracture. A satisfactory postoperative reduction implying less than 2 mm of displacement was achieved in 19 (86.36% patients. The radiological status of the hip joint, determined according to Matta score, was excellent in 15 (68.18% patients, good in 4 (18.18% patients and moderate in 3 (13.63% patients. According to Merle d’Aubigné Scale, the final functional results of the treatment of all operated patients were excellent in 12 (54.54% patients, good in 7 (31.81% patients and moderate in 3 (13.63% patients. Conclusion. Surgical treatment of dislocated acetabular fractures requires an open reduction and a stable internal fixation. Excellent and good results can be expected only if anatomical reduction and stable internal fixation are achieved.

  3. Displacement of soil pore water by trichloroethylene

    Wershaw, R. L.; Aiken, G.R.; Imbrigiotta, T.E.; Goldberg, M.C.


    Dense nonaqueous phase liquids (DNAPLS) are important pollutants because of their widespread use as chemical and industrial solvents. An example of the pollution caused by the discharge of DNAPLs is found at the Picatinny Arsenal, New Jersey, where trichloroethylene (TCE) has been discharged directly into the unsaturated zone. This discharge has resulted in the formation of a plume of TCE-contaminated water in the aquifer downgradient of the discharge. A zone of dark-colored groundwater containing a high dissolved organic C content has been found near the point of discharge of the TCE. The colored-water plume extends from the point of discharge at least 30 m (100 feet) downgradient. Fulvic acids isolated from the colored-waters plume, from water from a background well that has not been affected by the discharge of chlorinated solvents, and from soil pore water collected in a lysimeter installed at an uncontaminated site upgradient of the study area have been compared. Nuclear magnetic resonance spectra of the fulvic acids from the colored waters and from the lysimeter are very similar, but are markedly different from the nuclear magnetic resonance spectrum of the fulvic acid from the background well. The three-dimensional fluorescence spectrum and the DOC fractionation profile of the colored groundwater and the soil pore water are very similar to each other, but quite different from those of the background water. It is proposed from these observations that this colored water is soil pore water that has been displaced by a separate DNAPL liquid phase downward to the saturated zone.

  4. How minimum detectable displacement in a GNSS Monitoring Network change?

    Hilmi Erkoç, Muharrem; Doǧan, Uǧur; Aydın, Cüneyt


    The minimum detectable displacement in a geodetic monitoring network shows the displacement magnitude which may be just discriminated with known error probabilities. This displacement, which is originally deduced from sensitivity analysis, depends on network design, observation accuracy, datum of the network, direction of the displacement and power of the statistical test used for detecting the displacements. One may investigate how different scenarios on network design and observation accuracies influence the minimum detectable displacements for the specified datum, a-priorly forecasted directions and assumed power of the test and decide which scenario is the best or most optimum. It is sometimes difficult to forecast directions of the displacements. In that case, the minimum detectable displacements in a geodetic monitoring network are derived on the eigen-directions associated with the maximum eigen-values of the network stations. This study investigates how minimum detectable displacements in a GNSS monitoring network change depending on the accuracies of the network stations. For this, CORS-TR network in Turkey with 15 stations (a station fixed) is used. The data with 4h, 6h, 12 h and 24 h observing session duration in three sequential days of 2011, 2012 and 2013 were analyzed with Bernese 5.2 GNSS software. The repeatabilities of the daily solutions belonging to each year were analyzed carefully to scale the Bernese cofactor matrices properly. The root mean square (RMS) values for daily repeatability with respect to the combined 3-day solution are computed (the RMS values are generally less than 2 mm in the horizontal directions (north and east) and < 5 mm in the vertical direction for 24 h observing session duration). With the obtained cofactor matrices for these observing sessions, the minimum detectable displacements along the (maximum) eigen directions are compared each other. According to these comparisons, more session duration less minimum detectable

  5. Effect of displaced versus non-displaced pelvic fractures on long-term racing performance in 31 Thoroughbred racehorses.

    Hennessy, S E; Muurlink, M A; Anderson, G A; Puksmann, T N; Whitton, R C


    To evaluate the long-term racing prognosis for Thoroughbred racehorses with displaced versus non-displaced fractures of the pelvis identified by scintigraphy. Retrospective case analysis. Medical records of 31 Thoroughbred racehorses presenting to the University of Melbourne Equine Centre with fractures of the pelvis that were identified by scintigraphy were reviewed. Pelvic fracture site was determined and defined as displaced or non-displaced based on ultrasound and/or radiographic findings. Race records were analysed for each horse, with a minimum of 24 months' follow-up, and correlated with fracture type to determine long-term prognosis for racing. Results are expressed as median and range. Fractures at a single site were more common (n = 22) than fractures involving two sites (n = 9) and the ilial wing was the most commonly affected (n = 12). Thoroughbred racehorses with displaced pelvic fractures at any site (n = 12) raced fewer times within 24 months of diagnosis than horses with non-displaced fractures (n = 19) (median 0.5, range 0-13 vs 7, 0-24; P = 0.037), but there was no clear statistical difference in race earnings between the two groups (median A$0, range A$0-$123,250 vs A$14,440, A$0-$325,500, respectively; P = 0.080). Four horses with displaced fractures (33%) were euthanased on humane grounds because of persistent severe pain. When these horses were excluded from the analysis, there were no differences in performance variables between horses with a displaced or non-displaced pelvic fracture. Thoroughbred racehorses with a displaced or non-displaced pelvic fracture that survive the initial post-injury period have a good prognosis for racing. © 2013 The Authors. Australian Veterinary Journal © 2013 Australian Veterinary Association.

  6. Prediction of ground surface displacement caused by grouting

    郭风琪; 刘晓潭; 童无期; 单智


    Ground surface displacement caused by grouting was calculated with stochastic medium theory. Ground surface displacement was assumed to be caused by the cavity expansion of grouting, slurry seepage, and slurry contraction. A prediction method of ground surface displacement was developed. The reliability of the presented method was validated through a comparison between theoretical results and results from engineering practice. Results show that the present method is effective. The effect of parameters on uplift displacement was illustrated under different grouting conditions. Through analysis, it can be known that the ground surface uplift is mainly caused by osmosis of slurry and the primary influence angle of stratum βdetermines the influence range of surface uplift. Besides, the results show that ground surface uplift displacement decreases notably with increasing depth of the grouting cavity but it increases with increasing diffusion radius of grout and increasing grouting pressure.

  7. Evolution of displacements and strains in sheared amorphous solids

    Maloney, Craig E [Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA (United States); Robbins, Mark O [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD (United States)], E-mail:, E-mail:


    The local deformation of two-dimensional Lennard-Jones glasses under imposed shear strain is studied via computer simulations. Both the mean squared displacement and mean squared strain rise linearly with the length of the strain interval {delta}{gamma} over which they are measured. However, the increase in displacement does not represent single-particle diffusion. There are long-range spatial correlations in displacement associated with slip lines with an amplitude of order the particle size. Strong dependence on system size is also observed. The probability distributions of displacement and strain are very different. For small {delta}{gamma} the distribution of displacement has a plateau followed by an exponential tail. The distribution becomes Gaussian as {delta}{gamma} increases to about 0.03. The strain distributions consist of sharp central peaks associated with elastic regions, and long exponential tails associated with plastic regions. The latter persist to the largest {delta}{gamma} studied.

  8. Human response to ductless personalized ventilation coupled with displacement ventilation

    Dalewski, Mariusz; Veselý, Michal; Melikov, Arsen K.


    A human subject experiment was carried out to investigate the extent to which ductless personalized ventilation (DPV) in conjunction with displacement ventilation can improve perceived air quality (PAQ) and thermal comfort at elevated room air temperature in comparison with displacement ventilation...... alone. The experimental conditions comprised displacement ventilation alone (room air temperature of 23 °C, 26 °C, 29 °C) and DPV with displacement ventilation (26 °C, 29 °C), both operating at supply air temperatures 3, 5 or 6K lower than room air temperature, as well as mixing ventilation (23 °C, 3 K......). During one hour exposure participants answered questionnaires regarding PAQ and thermal comfort. PAQ was significantly better with DPV than without DPV at the same background conditions. Thermal comfort improved when DPV was used. Combining DPV with displacement ventilation showed the potential...

  9. [Displacement and tissue remodeling of temporomandibular joint disc].

    Wang, M Q


    Sounding takes the highest prevalence of the signs of temporomandibular disorders (TMD). The well accepted theory of the mechanism for temporomandibular joint (TMJ) sounding is the internal derangement typically characterized by disc displacement. However, according to literature, there are approximately one third of asymptomatic joints in population had disc displacement, and, on the other hand, there are one fourth of TMJ sounding patients had not signs or very limited signs of disc displacement. Replacing the displaced disc to the normal position via methods like surgical operation did not achieve satisfactory long-term outcomes. In this review, we discuss and analyze the possible remodeling of the joint disc displacement diagnosed with imaging based on the anatomy and pathophysiology.

  10. Programmable energy landscapes for kinetic control of DNA strand displacement.

    Machinek, Robert R F; Ouldridge, Thomas E; Haley, Natalie E C; Bath, Jonathan; Turberfield, Andrew J


    DNA is used to construct synthetic systems that sense, actuate, move and compute. The operation of many dynamic DNA devices depends on toehold-mediated strand displacement, by which one DNA strand displaces another from a duplex. Kinetic control of strand displacement is particularly important in autonomous molecular machinery and molecular computation, in which non-equilibrium systems are controlled through rates of competing processes. Here, we introduce a new method based on the creation of mismatched base pairs as kinetic barriers to strand displacement. Reaction rate constants can be tuned across three orders of magnitude by altering the position of such a defect without significantly changing the stabilities of reactants or products. By modelling reaction free-energy landscapes, we explore the mechanistic basis of this control mechanism. We also demonstrate that oxDNA, a coarse-grained model of DNA, is capable of accurately predicting and explaining the impact of mismatches on displacement kinetics.

  11. Land Restitution and Prevention of Forced Displacement in Colombia

    Felipe Gómez-Isa


    Full Text Available The armed conflict in Colombia, which has generated over three million internally displaced persons, has dramatic humanitarian consequences and raises serious issues regarding the protection of displaced peoples’ rights. The underlying reasons for the displacement often lie in the dynamics associated with territorial control and land seizures undertaken for strategic, military or purely economic purposes. Domestic and international legal provisions have established the victims’ right to the restitution of their homes and property as the “preferred remedy” in cases of displacement. However, policies dealing with displacement, both those of the Colombian government and of several international institutions, fail to take this sufficiently into account. A comprehensive reparation policy for victims must necessarily entail the reversion of lands, territories and goods seized in Colombia under the pretext of the internal armed conflict.

  12. Displacement of maxillary third molar into the lateral pharyngeal space.

    Lee, Doksa; Ishii, Syoichiro; Yakushiji, Noboru


    Iatrogenic tooth displacement is a rare complication during extraction of impacted molars, but displacement of a maxillary third molar into the maxillary sinus, infratemporal fossa, buccal space, pterygomandibular space, and lateral pharyngeal space has been reported. Currently, 6 published reports describe third molar displacement into the lateral pharyngeal space, only 1 of which involved the loss of a maxillary third molar into this area, which occurred after an attempted self-extraction by the patient. There have been no reported cases of iatrogenic displacement of the maxillary third molar during an extraction procedure. This article describes the recovery, under general anesthesia, of a maxillary third molar from the lateral pharyngeal space after an iatrogenic displacement.

  13. CVN 68 Class Displacement Concerns; Dealing with the Differences between the Modeled and Actual Displacements


    It is the second case that is most important for a ship in the water. It has been referred to as a special case of Archimedes ’ Principle , or the...from the bottom of the block to the waterline. Figure 6. Wooden block in water As described above using Archimedes ’ Principle , the weight of the...carrier. Archimedes ’ Law was discussed, as well as how this principle is applied to the displacement of an object in a body of water. The application

  14. Vagal denervation in atrial fibrillation ablation: A comprehensive review.

    Aksu, Tolga; Güler, Tümer Erdem; Mutluer, Ferit Onur; Oto, Mehmet Ali


    Although pulmonary vein isolation is accepted as an established interventional treatment in paroxysmal atrial fibrillation (AF), alternative modalities are being investigated because of the high recurrence rates of nonparoxysmal forms. One of the alternative ablation approaches is ablation or modification of vagal ganglionated plexi (VGP). The technique has not only been used in vagally mediated AF but also investigated in paroxysmal and nonparoxysmal AF. Clinical studies demonstrate significant discrepancy related with detection of VGP sites or ablation targets and definition of procedurel end-points, so far. In this review, we aimed to discuss the current data on the role of VGP in the pathogenesis of AF and potential therapeutic implications of ablation of these ganglia.

  15. Intra-cardiac echocardiography in alcohol septal ablation

    Cooper, Robert M; Shahzad, Adeel; Newton, James;


    Alcohol septal ablation (ASA) in hypertrophic obstructive cardiomyopathy reduces left ventricular outflow tract gradients. A third of patients do not respond; inaccurate localisation of the iatrogenic infarct can be responsible. Transthoracic echocardiography (TTE) using myocardial contrast can b...

  16. Computer-aided hepatic tumour ablation requirements and preliminary results

    Voirin, D; Amavizca, M; Letoublon, C; Troccaz, J; Voirin, David; Payan, Yohan; Amavizca, Miriam; Letoublon, Christian; Troccaz, Jocelyne


    Surgical resection of hepatic tumours is not always possible, since it depends on different factors, among which their location inside the liver functional segments. Alternative techniques consist in local use of chemical or physical agents to destroy the tumour. Radio frequency and cryosurgical ablations are examples of such alternative techniques that may be performed percutaneously. This requires a precise localisation of the tumour placement during ablation. Computer-assisted surgery tools may be used in conjunction with these new ablation techniques to improve the therapeutic efficiency, whilst they benefit from minimal invasiveness. This paper introduces the principles of a system for computer-assisted hepatic tumour ablation and describes preliminary experiments focusing on data registration evaluation. To keep close to conventional protocols, we consider registration of pre-operative CT or MRI data to intra-operative echographic data.

  17. Universal threshold for femtosecond laser ablation with oblique illumination

    Liu, Xiao-Long; Cheng, Weibo; Petrarca, Massimo; Polynkin, Pavel


    We quantify the dependence of the single-shot ablation threshold on the angle of incidence and polarization of a femtosecond laser beam, for three dissimilar solid-state materials: a metal, a dielectric, and a semiconductor. Using the constant, linear value of the index of refraction, we calculate the laser fluence transmitted through the air-material interface at the point of ablation threshold. We show that, in spite of the highly nonlinear ionization dynamics involved in the ablation process, the so defined transmitted threshold fluence is universally independent of the angle of incidence and polarization of the laser beam for all three material types. We suggest that angular dependence of ablation threshold can be utilized for profiling fluence distributions in ultra-intense femtosecond laser beams.

  18. Morphology Characterization of Uranium Particles From Laser Ablated Uranium Materials


    In the study, metallic uranium and uranium dioxide material were ablated by laser beam in order to simulate the process of forming the uranium particles in pyrochemical process. The morphology characteristic of uranium particles and the surface of

  19. Corneal surface morphology following excimer laser ablation with humidified gases.

    Krueger, R R; Campos, M; Wang, X W; Lee, M; McDonnell, P J


    To compare the effects of blowing dry (nitrogen or helium) and humidified gases over the corneal surface during photorefractive keratectomy. Excimer laser myopic ablations were performed on porcine eyes (10 per group) using humidified and dry nitrogen and helium gas under ambient conditions. Surface smoothness was quantified with light and electron microscopy. Corneas that were ablated using humidified gas were smooth and equivalent to those ablated under ambient conditions. Dry nitrogen and helium blowing resulted in increased surface irregularity evident on light and electron microscopy (P excimer laser corneal ablation produces a smoother surface than does the blowing of dry gas and is comparable to that produced under ambient (no blowing) conditions. Maintaining corneal moisture is important in photorefractive keratectomy. If blowing gas is necessary to remove debris from the surface, the gas should be humidified.

  20. Efficiency of Planetesimal Ablation in Giant Planetary Envelopes

    Pinhas, Arazi; Clarke, Cathie


    Observations of exoplanetary spectra are leading to unprecedented constraints on their atmospheric elemental abundances, particularly O/H, C/H, and C/O ratios. Recent studies suggest that elemental ratios could provide important constraints on formation and migration mechanisms of giant exoplanets. A fundamental assumption in such studies is that the chemical composition of the planetary envelope represents the sum-total of compositions of the accreted gas and solids during the formation history of the planet. We investigate the efficiency with which accreted planetesimals ablate in a giant planetary envelope thereby contributing to its composition rather than sinking to the core. From considerations of aerodynamic drag causing `frictional ablation' and the envelope temperature structure causing `thermal ablation', we compute mass ablations for impacting planetesimals of radii 30 m to 1 km for different compositions (ice to iron) and a wide range of velocities and impact angles, assuming spherical symmetry. I...

  1. Anatomical Consideration in Catheter Ablation of Idiopathic Ventricular Arrhythmias.

    Yamada, Takumi; Kay, G Neal


    Idiopathic ventricular arrhythmias (VAs) are ventricular tachycardias (VTs) or premature ventricular contractions (PVCs) with a mechanism that is not related to myocardial scar. The sites of successful catheter ablation of idiopathic VA origins have been progressively elucidated and include both the endocardium and, less commonly, the epicardium. Idiopathic VAs usually originate from specific anatomical structures such as the ventricular outflow tracts, aortic root, atrioventricular (AV) annuli, papillary muscles, Purkinje network and so on, and exhibit characteristic electrocardiograms based on their anatomical background. Catheter ablation of idiopathic VAs is usually safe and highly successful, but can sometimes be challenging because of the anatomical obstacles such as the coronary arteries, epicardial fat pads, intramural and epicardial origins, AV conduction system and so on. Therefore, understanding the relevant anatomy is important to achieve a safe and successful catheter ablation of idiopathic VAs. This review describes the anatomical consideration in the catheter ablation of idiopathic VAs.

  2. Mechanochemical endovenous Ablation versus RADiOfrequeNcy Ablation in the treatment of primary great saphenous vein incompetence (MARADONA) : study protocol for a randomized controlled trial

    van Eekeren, Ramon R. J. P.; Boersma, Doeke; Holewijn, Suzanne; Vahl, Anco; de Vries, Jean Paul P. M.; Zeebregts, Clark J.; Reijnen, Michel M. P. J.


    Background: Radiofrequency ablation (RFA) is associated with an excellent outcome in the treatment of great saphenous vein (GSV) incompetence. The use of thermal energy as a treatment source requires the instillation of tumescence anesthesia. Mechanochemical endovenous ablation (MOCA) combines

  3. Mechanochemical endovenous Ablation versus RADiOfrequeNcy Ablation in the treatment of primary great saphenous vein incompetence (MARADONA) : study protocol for a randomized controlled trial

    van Eekeren, Ramon R. J. P.; Boersma, Doeke; Holewijn, Suzanne; Vahl, Anco; de Vries, Jean Paul P. M.; Zeebregts, Clark J.; Reijnen, Michel M. P. J.


    Background: Radiofrequency ablation (RFA) is associated with an excellent outcome in the treatment of great saphenous vein (GSV) incompetence. The use of thermal energy as a treatment source requires the instillation of tumescence anesthesia. Mechanochemical endovenous ablation (MOCA) combines mecha

  4. Spectroscopy Measurements on Ablation Testing in High Enthalpy Plasma Flows


    stagnation point, are located on the ablative material sample. 3.5 InfraRed THERMOGRAPHY Surface temperature measurement is a topic of great concern...high temperature material at two different narrow wavelengths. The temperature is calculated by building the ratio of the radiation intensities. The...this work is to develop the capability of testing and characterization of ablative materials exposed to high enthalpy plasma flows including both

  5. Ablation from metals induced by visible and UV laser irradiation

    Svendsen, Winnie Edith; Schou, Jørgen; Thestrup Nielsen, Birgitte


    The deposition rate of laser-ablated silver has been determined for fluences between 0.5 and 15 J/cm2 at the wavelengths 532 and 355 nm for a beam spot area of around 0.01 cm2. The ablated metal was collected on a quartz crystal microbalance. The rate at 5 J/cm2 was about 4 × 1013 Ag/cm2 per puls...

  6. Isotope Effects of Solid Hydrogenic Pellet Ablation in Fusion Plasma

    PENGLilin; DENGBaiquan; YANJiancheng; WANGXiaoyu


    The isotope effects of ablation processes in fusion plasma for five combinations of solid isotopic hydrogenic pellets H2, HD, D2,DT, T2 have been first time studied. The resuits show that the modifications caused by isotope effects for pellet erosion speeds range from 1 for hydrogen pellet down to 0. 487 for tritium pellet and are not negligible in ablation rate calculations. These effects lead to deeper mass deposition and improved core fueling efficiency.

  7. Pulsed laser ablation and deposition of niobium carbide

    Sansone, M.; De Bonis, A.; Santagata, A.; Rau, J. V.; Galasso, A.; Teghil, R.


    NbC crystalline films have been deposited in vacuum by ultra-short pulsed laser deposition technique. The films have been characterized by transmission and scanning electron microscopies and by X-ray diffraction. To clarify the ablation-deposition mechanism, the plasma produced by the ablation process has been characterized by optical emission spectroscopy and fast imaging. A comparison of the results with those obtained by ns pulsed deposition of the same target has been carried out.

  8. Langmuir probe study of plasma expansion in pulsed laser ablation

    Hansen, T.N.; Schou, Jørgen; Lunney, J.G.


    Langmuir probes were used to monitor the asymptotic expansion of the plasma produced by the laser ablation of a silver target in a vacuum. The measured angular and temporal distributions of the ion flux and electron temperature were found to be in good agreement with the self-similar isentropic...... and adiabatic solution of the gas dynamics equations describing the expansion. The value of the adiabatic index gamma was about 1.25, consistent with the ablation plume being a low temperature plasma....

  9. Enthalpy model for heating, melting, and vaporization in laser ablation

    Vasilios Alexiades; David Autrique


    Laser ablation is used in a growing number of applications in various areas including medicine, archaeology, chemistry, environmental and materials sciences. In this work the heat transfer and phase change phenomena during nanosecond laser ablation of a copper (Cu) target in a helium (He) background gas at atmospheric pressure are presented. An enthalpy model is outlined, which accounts for heating, melting, and vaporization of the target. As far as we know, this is the first model th...

  10. Optimization of the generator settings for endobiliary radiofrequency ablation

    Maximilien; Barret; Sarah; Leblanc; Ariane; Vienne; Alexandre; Rouquette; Frederic; Beuvon; Stanislas; Chaussade; Frederic; Prat


    AIM:To determine the optimal generator settings for endobiliary radiofrequency ablation. METHODS:Endobiliary radiofrequency ablation was performed in live swine on the ampulla of Vater,the common bile duct and in the hepatic parenchyma. Radiofrequency ablation time,"effect",and power were allowed to vary. The animals were sacrificed two hours after the procedure. Histopathological assessment of the depth of the thermal lesions was performed. RESULTS:Twenty-five radiofrequency bursts were applied in three swine. In the ampulla of Vater(n = 3),necrosis of the duodenal wall was observed starting with an effect set at 8,power output set at 10 W,and a 30 s shot duration,whereas superficial mucosal damage of up to 350 μm in depth was recorded for an effect set at 8,power output set at 6 W and a 30 s shot duration. In the common bile duct(n = 4),a 1070 μm,safe and efficient ablation was obtained for an effect set at 8,a power output of 8 W,and an ablation time of 30 s. Within the hepatic parenchyma(n = 18),the depth of tissue damage varied from 1620 μm(effect = 8,power = 10 W,ablation time = 15 s) to 4480 μm(effect = 8,power = 8 W,ablation time = 90 s). CONCLUSION:The duration of the catheter application appeared to be the most important parameter influencing the depth of the thermal injury during endobiliary radiofrequency ablation. In healthy swine,the currently recommended settings of the generator may induce severe,supratherapeutic tissue damage in the biliary tree,especially in the high-risk area of the ampulla of Vater.

  11. Simulation of femtosecond pulsed laser ablation of metals

    Davydov, R. V.; Antonov, V. I.


    In this paper a mathematical model for femtosecond laser ablation of metals is proposed, based on standard two-temperature model connected with 1D hydrodynamic equations. Wide-range equation of state has been developed. The simulation results are compared with experimental data for aluminium and copper. A good agreement for both metals with numerical results and experiment shows that this model can be employed for choosing laser parameters to better accuracy in nanoparticles production by ablation of metals.

  12. UV laser ablation of parylene films from gold substrates

    O. R. Musaev, P. Scott, J. M. Wrobel, and M. B. Kruger


    Parylene films, coating gold substrates, were removed by laser ablation using 248 nm light from an excimer laser. Each sample was processed by a different number of pulses in one of three different environments: air at atmospheric pressure, nitrogen at atmospheric pressure, and vacuum. The laser-induced craters were analyzed by optical microscopy and x-ray photoelectron spectroscopy. Multi-pulse ablation thresholds of gold and parylene were estimated.

  13. The characteristics of confined ablation in laser propulsion

    Zheng Zhi-Yuan; Zhang Jie; Hao Zuo-Qiang; Yuan Xiao-Hui; Zhang Zhe; Lu Xin; Wang Zhao-Hua; Wei Zhi-Yi


    Compared with direct ablation, confined ablation provides an effective way to obtain a large target momentum and a high coupling coefficient. By using a transparent glass layer to cover the target surface, the coupling coefficient is enhanced by an order of magnitude. With the increase of the gap width between the target surface and the cover layer, the coupling coefficient exponentially decreases. It is found that the coupling coefficient is also related to the thickness of the cover layer.

  14. Plasma mediated ablation of biological tissues with ultrashort laser pulses

    Oraevsky, A.A. [Lawrence Livermore National Lab., CA (United States)]|[Rice Univ., Houston, TX (United States). Dept. of Electrical Engineering; DaSilva, L.B.; Feit, M.D. [Lawrence Livermore National Lab., CA (United States)] [and others


    Plasma mediated ablation of collagen gels and porcine cornea was studied at various laser pulse durations in the range from 350 fs to 1 ns at 1,053 nm wavelength. A time resolved stress detection technique was employed to measure transient stress profiles and amplitudes. Optical microscopy was used to characterize ablation craters qualitatively, while a wide band acoustic transducer helped to quantify tissue mechanical response and the ablation threshold. The ablation threshold was measured as a function of laser pulse duration and linear absorption coefficient. For nanosecond pulses the ablation threshold was found to have a strong dependence on the linear absorption coefficient of the material. As the pulse length decreased into the subpicosecond regime the ablation threshold became insensitive to the linear absorption coefficient. The ablation efficiency was found to be insensitive to both the laser pulse duration and the linear absorption coefficient. High quality ablation craters with no thermal or mechanical damage to surrounding material were obtained with 350 fs laser pulses. The mechanism of optical breakdown at the tissue surface was theoretically investigated. In the nanosecond regime, optical breakdown proceeds as an electron collisional avalanche ionization initiated by thermal seed electrons. These seed electrons are created by heating of the tissue by linear absorption. In the ultrashort pulse range, optical breakdown is initiated by the multiphoton ionization of the irradiated medium (6 photons in case of tissue irradiated at 1,053 nm wavelength), and becomes less sensitive to the linear absorption coefficient. The energy deposition profile is insensitive to both the laser pulse duration and the linear absorption coefficient.

  15. A case of splenic abscess after radiofrequency ablation

    Dimitris Zacharoulis; Emmanuel Katsogridakis; Constantinos Hatzitheofilou


    Radiofrequency ablation (RFA) is an innovative technique used primarily for the palliative treatment of unresectable liver tumors. Its therapeutic indications however, have been expanded and now include various other organs and diseases. There is a paucity of data regarding technical details and complications of the use of RFA in the spleen. We report a case of partial splenectomy using radiofrequency ablation for splenic hydatid disease,complicated by an abscess formation.

  16. Successful treatment of hepatic oligometastases with stereotactic ablative radiotherapy and radiofrequency ablation in an anaplastic lymphoma kinase fusion-positive lung cancer patient

    Weber, Britta; Liu, Mitchell; Sobkin, Paul


    Local ablative therapy with stereotactic ablative radiotherapy may improve survival in oncogene‐addicted lung cancer patients with extracranial oligometastatic disease treated with targeted therapies. There is limited data on the use of radiofrequency ablation (RFA) in this same setting. We present...... a case of an anaplastic lymphoma kinase (ALK)‐positive lung cancer patient with hepatic oligometastatic progression who was successfully treated with both stereotactic ablative radiation and RFA while continuing with an ALK inhibitor....

  17. Determining Fault Geometries From Surface Displacements

    Volkov, D.; Voisin, C.; Ionescu, I. R.


    We introduce a new algorithm for determining the geometry of active parts of faults. This algorithm uses surface measurements of displacement fields and local modeling of the Earth's crust as a half-space elastic medium. The numerical method relies on iterations alternating non-linear steps for recovering the geometry and linear steps for reconstructing slip fields. Our algorithm greatly improves upon past attempts at reconstructing fault profiles. We argue that these past attempts suffered from either the restrictive assumption that the geometry of faults can be derived using only uniformly constant slips or that they relied on arbitrary assumptions on the statistics of the reconstruction error. We test this algorithm on the 2006 Guerrero, Mexico, slow slip event (SSE) and on the 2009 SSE for the same region. These events occurred on a relatively well-known subduction zone, whose geometry was derived from seismicity and gravimetric techniques, see Kostoglodov et al. (Geophys Res Lett 23(23):3385-3388, 1996), Pardo and Suarez (J Geophys Res 100(B7):357-373, 1995), Singh and Pardo (Geophys Res Lett 20(14):1483-1486, 1993), so our results can be compared to known benchmarks. Our derived geometry is found to be consistent with these benchmarks regarding dip and strike angles and the positioning of the North American Trench. In addition, our derived slip distribution is also consistent with previous studies (all done with an assumed fixed geometry), see Larson et al. (Geophys Res Lett 34(13), 2007), Bekaert et al. (J Geophys Res: Solid Earth 120(2):1357-1375, 2015), Radiguet et al. (Geophys J Int 184(2):816-828, 2011, J Geophys Res 2012), Rivet et al. (Geophys Res Lett 38(8), 2011), Vergnolle et al. (J Geophys Res: Solid Earth 115(B8), 2010), Walpersdorf et al. Geophys Res Lett 38(15), 2011), to name a few. We believe that the new computational inverse method introduced in this paper holds great promise for applications to blind inversion cases, where both geometry and

  18. A Rare Complication of Radiofrequency Tonsil Ablation: Horner Syndrome

    Cuneyt Kucur


    Full Text Available Chronic tonsillitis is a common disease, and several different surgical techniques are used to treat this condition. In recent years, techniques such as radiofrequency ablation and coblation have been commonly used for tonsil surgery. In this report, we present the cases of two pediatric patients who developed ptosis, miosis, and enophthalmos (Horner syndrome after radiofrequency ablation for tonsil reduction and discuss the technique of radiofrequency ablation of the tonsils. In the early postoperative period, miosis and ptosis were observed on the right side in one patient and on the left side in the other patient. Both patients were treated with 1 mg/kg/day methylprednisolone, which were tapered by halving the dose every 3 days. Miosis and ptosis improved after treatment in both patients. Along with the case presentation, we discuss the effectiveness and complications of radiofrequency ablation of the tonsils. These unusual complications of tonsil ablation may help ENT physicians who do not yet have a preferred surgical technique for tonsillectomy to make an informed decision. Limited data are available about the possible complications of radiofrequency ablation of the tonsils. The present report contributes to the literature on this topic.

  19. The effect of asteroid topography on surface ablation deflection

    McMahon, Jay W.; Scheeres, Daniel J.


    Ablation techniques for deflecting hazardous asteroids deposit energy into the asteroid's surface, causing an effective thrust on the asteroid as the ablating material leaves normal to the surface. Although it has long been recognized that surface topography plays an important role in determining the deflection capabilities, most studies to date have ignored this aspect of the model. This paper focuses on understanding the topography for real asteroid shapes, and how this topography can change the deflection performance of an ablation technique. The near Earth asteroids Golevka, Bennu, and Itokawa are used as the basis for this study, as all three have high-resolution shape models available. This paper shows that naive targeting of an ablation method without accounting for the surface topography can lower the deflection performance by up to 20% in the cases studied in terms of the amount of acceleration applied in the desired direction. If the ablation thrust level is assumed to be 100 N, as used elsewhere in the literature, this misapplication of thrust translates to tens of kilometers per year in decreased semimajor axis change. However, if the ablation method can freely target any visible point on the surface of the asteroid, almost all of this performance can be recovered.

  20. Radiofrequency Ablation Treatment for Renal Cell Carcinoma: Early Clinical Experience

    Park, Seong Hoon; Yoon, Seong Kuk; Cho, Jin Han; Oh, Jong Young; Nam, Kyung Jin; Kwon, Hee Jin; Kim, Su Yeon; Kang, Myong Jin; Choi, Sun Seob; Sung, Gyung Tak [Dong-A University College of Medicine, Busan (Korea, Republic of)


    To evaluate the early clinical experience associated with radiofrequency (RF) ablation in patients with renal cell carcinoma (RCC). The RF ablation treatment was performed on 17 tumors from 16 patients (mean age, 60.5 years; range, 43 73 years) with RCC. The treatment indications were localized, solid renal mass, comorbidities, high operation risk, and refusal to perform surgery. All tumors were treated by a percutaneous CT (n = 10), followed by an US-guided (n = 2), laparoscopy-assisted US (n = 2), and an open (n = 2) RF ablation. Furthermore, patients underwent a follow- up CT at one day, one week, one month, three and six months, and then every six months from the onset of treatment. We evaluated the technical success, technical effectiveness, ablation zone, benign periablation enhancement, irregular peripheral enhancement, and complications. All 17 exophytic tumors (mean size, 2.2 cm; range, 1.1 5.0 cm) were completely ablated. Technical success and effectiveness was achieved in all cases and the mean follow-up period was 23.8 months (range, 17 33 months). A local recurrence was not detected in any of the cases; however, five patients developed complications as a result of treatment, including hematuria (n = 2), mild thermal injury of the psoas muscle (n = 1), mild hydronephrosis (n = 1), and fistula formation (n = 1). The RF ablation is an alternative treatment for exophytic RCCs and represents a promising treatment for some patients with small RCCs.