Interaction of laser generated ultrasonic waves with wedge-shaped samples

Wedge-shaped samples can be used as a model of acoustic interactions with samples ranging from ocean wedges, to angled defects such as rolling contact fatigue, to thickness measurements of samples with non-parallel faces. We present work on laser generated ultrasonic waves on metal samples; one can measure the dominant Rayleigh-wave mode, but longitudinal and shear waves are also generated. We present calculations, models, and measurements giving the dependence of the arrival times and amplitudes of these modes on the wedge apex angle and the separation of generation and detection points, and hence give a measure of the wedge characteristics

Designing a Story Database for Use in Automatic Story Generation

In this paper we propose a model for the representation of stories in a story database. The use of such a database will enable computational story generation systems to learn from previous stories and associated user feedback, in order to create believable stories with dramatic plots that invoke an emotional response from users. Some of the distinguishing characteristics of our proposal are the inclusion of what we call ‘narratological concepts’ and user feedback in the story database

Development of a protein marker panel for characterization of human induced pluripotent stem cells (hiPSCs) using global quantitative proteome analysis

AbstractThe emergence of new methods for reprogramming of adult somatic cells into induced pluripotent stem cells (iPSC) led to the development of new approaches in drug discovery and regenerative medicine. Investigation of the molecular mechanisms underlying the self-renewal, expansion and differentiation of human iPSC (hiPSC) should lead to improvements in the manufacture of safe and reliable cell therapy products. The goal of our study was qualitative and quantitative proteomic characterizations of hiPSC by means of electrospray ionization (ESI)-MSe and MALDI-TOF/TOF mass spectrometry (MS). Proteomes of hiPSCs of different somatic origins: fibroblasts and peripheral blood CD34+ cells, reprogrammed by the same technique, were compared with the original somatic cells and hESC. Quantitative proteomic comparison revealed approximately 220 proteins commonly up-regulated in all three pluripotent stem cell lines compared to the primary cells. Expression of 21 proteins previously reported as pluripotency markers was up-regulated in both hiPSCs (8 were confirmed by Western blot). A number of novel candidate marker proteins with the highest fold-change difference between hiPSCs/hESC and somatic cells discovered by MS were confirmed by Western blot. A panel of 22 candidate marker proteins of hiPSC was developed and expression of these proteins was confirmed in 8 additional hiPSC lines

Refraction Wiggles for Measuring Fluid Depth and Velocity from Video

We present principled algorithms for measuring the velocity and 3D location of refractive fluids, such as hot air or gas, from natural videos with textured backgrounds. Our main observation is that intensity variations related to movements of refractive fluid elements, as observed by one or more video cameras, are consistent over small space-time volumes. We call these intensity variations “refraction wiggles”, and use them as features for tracking and stereo fusion to recover the fluid motion and depth from video sequences. We give algorithms for 1) measuring the (2D, projected) motion of refractive fluids in monocular videos, and 2) recovering the 3D position of points on the fluid from stereo cameras. Unlike pixel intensities, wiggles can be extremely subtle and cannot be known with the same level of confidence for all pixels, depending on factors such as background texture and physical properties of the fluid. We thus carefully model uncertainty in our algorithms for robust estimation of fluid motion and depth. We show results on controlled sequences, synthetic simulations, and natural videos. Different from previous approaches for measuring refractive flow, our methods operate directly on videos captured with ordinary cameras, do not require auxiliary sensors, light sources or designed backgrounds, and can correctly detect the motion and location of refractive fluids even when they are invisible to the naked eye.Shell ResearchMotion Sensing Wi-Fi Sensor Networks Co. (Grant 6925133)National Science Foundation (U.S.). Graduate Research Fellowship (Grant 1122374)Microsoft Research (PhD Fellowship

Nonlinear viscosity and velocity distribution function in a simple longitudinal flow

A compressible flow characterized by a velocity field $u_x(x,t)=ax/(1+at)$ is analyzed by means of the Boltzmann equation and the Bhatnagar-Gross-Krook kinetic model. The sign of the control parameter (the longitudinal deformation rate $a$) distinguishes between an expansion ($a>0$) and a condensation ($a<0$) phenomenon. The temperature is a decreasing function of time in the former case, while it is an increasing function in the latter. The non-Newtonian behavior of the gas is described by a dimensionless nonlinear viscosity $\eta^*(a^*)$, that depends on the dimensionless longitudinal rate $a^*$. The Chapman-Enskog expansion of $\eta^*$ in powers of $a^*$ is seen to be only asymptotic (except in the case of Maxwell molecules). The velocity distribution function is also studied. At any value of $a^*$, it exhibits an algebraic high-velocity tail that is responsible for the divergence of velocity moments. For sufficiently negative $a^*$, moments of degree four and higher may diverge, while for positive $a^*$ the divergence occurs in moments of degree equal to or larger than eight.Comment: 18 pages (Revtex), including 5 figures (eps). Analysis of the heat flux plus other minor changes added. Revised version accepted for publication in PR

Use of specific Green's functions for solving direct problems involving a heterogeneous rigid frame porous medium slab solicited by acoustic waves

A domain integral method employing a specific Green's function (i.e., incorporating some features of the global problem of wave propagation in an inhomogeneous medium) is developed for solving direct and inverse scattering problems relative to slab-like macroscopically inhomogeneous porous obstacles. It is shown how to numerically solve such problems, involving both spatially-varying density and compressibility, by means of an iterative scheme initialized with a Born approximation. A numerical solution is obtained for a canonical problem involving a two-layer slab.Comment: submitted to Math.Meth.Appl.Sc

Lessons Learned from Open-label Deep Brain Stimulation for Tourette Syndrome: Eight Cases over 7 Years

Background: Deep brain stimulation (DBS) remains an experimental but promising treatment for patients with severe refractory Gilles de la Tourette syndrome (TS). Controversial issues include the selection of patients (age and clinical presentation), the choice of brain targets to obtain optimal patient-specific outcomes, and the risk of surgery- and stimulation-related serious adverse events. Methods: This report describes our open-label experience with eight patients with severe refractory malignant TS treated with DBS. The electrodes were placed in the midline thalamic nuclei or globus pallidus, pars internus, or both. Tics were clinically assessed in all patients pre- and postoperatively using the Modified Rush Video Protocol and the Yale Global Tic Severity Scale (YGTSS). Results: Although three patients had marked postoperative improvement in their tics (>50% improvement on the YGTSS), the majority did not reach this level of clinical improvement. Two patients had to have their DBS leads removed (one because of postoperative infection and another because of lack of benefit). Discussion Our clinical experience supports the urgent need for more data and refinements in interventions and outcome measurements for severe, malignant, and medication-refractory TS. Because TS is not an etiologically homogenous clinical entity, the inclusion criteria for DBS patients and the choice of brain targets will require more refinement