Experimental and Numerical Investigation of Therapeutic Ultrasound Angioplasty

Therapeutic ultrasound angioplasty is an emerging minimally invasive cardiovascular surgical procedure that involves the delivery of ultrasonic displacements to the distal-tip of small diameter wire waveguides. The ultrasonic distal-tip displacements affect atherosclerotic plaque and thrombus by direct contact ablation, pressure wave components and cavitation, in addition to an acoustic streaming event around the distal-tip. This study uses experimental and numerical methods to investigate ultrasonic displacements in wire waveguides and the effect the distal-tip displacements have on the surrounding fluid. An experimental therapeutic ultrasound wire waveguide apparatus is described that delivers displacements to the distal-tip of 1.0 mm and tapered 0.35 mm diameter nickel-titanium (NiTi) waveguides. The operating frequency of the apparatus has been experimentally determined to be 23.5 kHz and for the power settings tested delivers displacements of up to 85 µm peak-to-peak (p-p) to the distal-tip of 1.0 mm diameter waveguides. The apparatus has been shown to directly ablate calcified materials with a stiffer response when compared with atherosclerotic plaques and to generate cavitation and acoustic streaming. A coupled fluid-structure numerical model of the waveguide and fluid surrounding the distal-tip has been developed that predicts the waveguide displacements and stresses along the entire length of the wire waveguide. The structural results of the model have been validated against experimental measurements of the displacements of the waveguide with the inclusion of a constant damping value of 4.5%. The fluid results of the model predict the pressure amplitudes developed in the surrounding fluid and compare closely with values reported in literature. The model predicts the distal-tip displacements required to cause cavitation, a major disruptive event, and has been compared with experimental observations made with the ultrasonic wire waveguide apparatus. The waveguide numerical model will prove a valuable design tool in the further development and improvement of this emerging cardiovascular technology

El cambiante lenguaje del turismo: del monólogo al diálogo y al triálogo

Cuando empezó a desarrollarse el “lenguaje del turismo”, el turismo formaba parte del proyecto “modernista”, cuyo discurso unilateral y monológico había surgido bajo parámetros de control social. En la actualidad, sin embargo, tenemos pruebas de que este discurso ha sufrido una transformación, debido a la difusión de la comunicación digital en Internet. En efecto, existe hoy un espíritu “postmoderno”, más igualitario, abierto al diálogo e incluso al “triálogo” entre los principales interlocutores del turismo: la industria del turismo, el turista y la comunidad receptora. Por esta razón, resulta necesaria una nueva perspectiva heurística, que refl eje los cambios en tan rápida evolución. A continuación, se abordará un análisis sistemático de tres modelos constitutivos, que ilustran conjuntamente el paradigma cambiante de los medios de comunicación, hoy abiertos a la mayor democratización.When the “language of tourism” was initially articulated, tourism formed part of the modernist project, wherein its unilateral, monological discourse was framed within the parameters of social control. However, there is evidence today that it has now been transformed on account of the digitalised communication of the Internet. Indeed, there is currently a more egalitarian, postmodern ethos of dialogue, or even trialogue, between the key players of tourism: the industry, the tourist and the touree. Consequently, a new heuristic framework becomes necessary, one that refl ects the changes that are rapidly occurring. With examples, a cell-by-cell approach is adopted in three constituent models which together illustrate a shifting paradigm in terms of the media that are now open to greater democratisation

A Numerical Acoustic Fluid-structure Model of a Therapeutic Ultrasound Angioplasty Device

Ultrasonic angioplasty involves the use of ultrasonic vibrations delivered to the distal-tip of small diameter wire waveguides and is an emerging technology the may have potential use in the treatment of complicated atherosclerotic plaques during cardiovascular surgery. Complicated plaques, including chronic total occlusions and calcified lesions, seriously reduce success rates during standard intervention involving guidewire access, followed by balloon dilation or stent delivery. The large amplitude (0-150 μm) wire waveguide distal-tip displacements in the low-frequency ultrasonic (18-45 kHz) range have been shown to disrupt plaque material by direct contact ablation and cavitation, acoustic streaming and pressure wave components in adjacent fluid 1. The effects on this surrounding fluid are complex and are related to the distal-tip geometry, frequency of operation, vibration amplitude, as well as the operating environment, including, fluid properties and boundary conditions. While the majority of work to date on ultrasound angioplasty has focused on experimental and clinical studies 2, 3, further understanding of distal-tip effects is necessary. This work describes a numerical fluid-structure model of the wire waveguide distal-tip and is used to predict the pressures developed in the fluid region near the tip wall, the acoustic pressure field and, with the inclusion of appropriate threshold intensity, when cavitation will occur. The model has been validated against experimental acoustic pressure field results reported in the literature. The model can be further used to predict the effects of parameters such as distal-tip geometry, displacement amplitude and frequency of operation and will prove a valuable design aid in the choice of optimum powers to disrupt various biological materials

An enumerated probabilistic simulation technique and case study: Integrating wind power into utility production cost models

Production cost, generation expansion, and reliability models are used extensively by utilities in the planning process. However, many of these models do not provide adequate means for representing the full range of potential variation in wind power plants. In order to properly account for expected variation in wind-generated electricity in these models, we describe an enumerated probabilistic approach that can be performed outside the production cost model, compare it with a reduced enumerated approach, and present some selected utility results. Our technique can be applied to any model, and can result in a considerable reduction in model runs. We use both a load duration curve model and a chronological model to measure wind plant capacity credit, and also present some other selected results

PCN162 The Cost-Effectiveness of Second-Line Crizotinib in Eml4-Alk Rearranged Advanced Non-Small Cell Lung Cancer

Background: Snoring / sleep apnea are potentially life threatening breathing occurs during sleep. Little attention is being giving to this clinical condition. Objective: To determine the prevalence of snoring and risk factors associated with obstructive sleep apnea (OSA) among adults workers in two local governments of state, Nigeria Methodology: A cross - sectional survey of 121 young adult and adults working in two local governments of Ekiti state, south western Nigeria was carried out. A self administered questionnaire that was incorporated with Epworth Sleepiness Scale and Berlin Score was used to collect data on socio-demographic characteristics, information related to snoring, sleep related problems and their anthropometric. The Body Mass Index (BMI) and blood pressure of each participant were also measured. Results: Snoring was reported in forty nine (40.5%) of the participants. Their age ranges from 23 to 65 years, mean of 43.89 ± 8.53 SD. The proportion of males and Berlin score (high risk) were significantly (p < 0.001) higher among snores than non regression found sex (OR=7.791, 95% CI =2.971- 20.429), Berlin Score (high risk) (OR= 8.642, 95% CI= 3.159 - 23.639) as significant (P< 0.001) independent risk factors for OSA. Excessive day time sleepiness as determined by ESS score of the participants. Conclusion: The overall prevalence of snoring in this study was 40.5%. Snoring was found to increase with age, body mass index, male sex and those with high risk for Berlin score with high risk of developing Obstructive sleep apne

The Asymptotic distribution of circles in the orbits of Kleinian groups

Let P be a locally finite circle packing in the plane invariant under a non-elementary Kleinian group Gamma and with finitely many Gamma-orbits. When Gamma is geometrically finite, we construct an explicit Borel measure on the plane which describes the asymptotic distribution of small circles in P, assuming that either the critical exponent of Gamma is strictly bigger than 1 or P does not contain an infinite bouquet of tangent circles glued at a parabolic fixed point of Gamma. Our construction also works for P invariant under a geometrically infinite group Gamma, provided Gamma admits a finite Bowen-Margulis-Sullivan measure and the Gamma-skinning size of P is finite. Some concrete circle packings to which our result applies include Apollonian circle packings, Sierpinski curves, Schottky dances, etc.Comment: 31 pages, 8 figures. Final version. To appear in Inventiones Mat

Gamma Ray Lines from a Universal Extra Dimension

Indirect Dark Matter searches are based on the observation of secondary particles produced by the annihilation or decay of Dark Matter. Among them, gamma-rays are perhaps the most promising messengers, as they do not suffer deflection or absorption on Galactic scales, so their observation would directly reveal the position and the energy spectrum of the emitting source. Here, we study the detailed gamma-ray energy spectrum of Kaluza--Klein Dark Matter in a theory with 5 Universal Extra Dimensions. We focus in particular on the two body annihilation of Dark Matter particles into a photon and another particle, which produces monochromatic photons, resulting in a line in the energy spectrum of gamma rays. Previous calculations in the context of the five dimensional UED model have computed the line signal from annihilations into \gamma \gamma, but we extend these results to include \gamma Z and \gamma H final states. We find that these spectral lines are subdominant compared to the predicted \gamma \gamma signal, but they would be important as follow-up signals in the event of the observation of the \gamma \gamma line, in order to distinguish the 5d UED model from other theoretical scenarios.Comment: 21 pages, 6 figure

Vibrations of a chain of Xe atoms in a groove of carbon nanotube bundle

We present a lattice dynamics study of the vibrations of a linear chain of Xe adsorbates in groove positions of a bundle of carbon nanotubes. The characteristic phonon frequencies are calculated and the adsorbate polarization vectors discussed. Comparison of the present results with the ones previously published shows that the adsorbate vibrations cannot be treated as completely decoupled from the vibrations of carbon nanotubes and that a significant hybridization between the adsorbate and the tube modes occurs for phonons of large wavelengths.Comment: 3 PS figure

Geometry and material effects in Casimir physics - Scattering theory

We give a comprehensive presentation of methods for calculating the Casimir force to arbitrary accuracy, for any number of objects, arbitrary shapes, susceptibility functions, and separations. The technique is applicable to objects immersed in media other than vacuum, to nonzero temperatures, and to spatial arrangements in which one object is enclosed in another. Our method combines each object's classical electromagnetic scattering amplitude with universal translation matrices, which convert between the bases used to calculate scattering for each object, but are otherwise independent of the details of the individual objects. This approach, which combines methods of statistical physics and scattering theory, is well suited to analyze many diverse phenomena. We illustrate its power and versatility by a number of examples, which show how the interplay of geometry and material properties helps to understand and control Casimir forces. We also examine whether electrodynamic Casimir forces can lead to stable levitation. Neglecting permeabilities, we prove that any equilibrium position of objects subject to such forces is unstable if the permittivities of all objects are higher or lower than that of the enveloping medium; the former being the generic case for ordinary materials in vacuum.Comment: 44 pages, 11 figures, to appear in upcoming Lecture Notes in Physics volume in Casimir physic