A wind tunnel investigation of panel response to boundary layer pressure fluctuations at Mach 1.4 and Mach 3.5

Panel response to turbulent boundary layer pressure fluctuations in wind tunnel with supersonic flo

Investigation of the feasibility of making model acoustic measurements in the NASA Ames 40-by 80-foot wind tunnel

Feasibility of model acoustic measurements in wind tunnel for estimating total sound powe

Clinical Trial Simulation to Evaluate Population Pharmacokinetics and Food Effect: Capturing Abiraterone and Nilotinib Exposures

The objectives of this study were to determine (1) the accuracy with which individual patient level exposure can be determined and (2) whether a known food effect can be identified in a trial simulation of a typical population pharmacokinetic trial. Clinical trial simulations were undertaken using NONMEM VII to assess a typical oncology pharmacokinetic trial design. Nine virtual trials for each compound were performed for combinations of different level of between-occasion variability, number of patients in the trial and magnitude of a food covariate on oral clearance. Less than 5% and 20% bias and precision were obtained in individual clearance estimated for both abiraterone and nilotinib using this design. This design resulted biased and imprecise population clearance estimates for abiraterone. The between-occasion variability in most trials was captured with less than 30% of percent bias and precision. The food effect was detectable as a statistically significant covariate on oral clearance for abiraterone and nilotinib with percent bias and precision of the food covariate less than 20%. These results demonstrate that clinical trial simulation can be used to explore the ability of specific trial designs to evaluate the power to identify individual and population level exposures,covariate and variability effects

Semiclassical Construction of Random Wave Functions for Confined Systems

We develop a statistical description of chaotic wavefunctions in closed systems obeying arbitrary boundary conditions by combining a semiclassical expression for the spatial two-point correlation function with a treatment of eigenfunctions as Gaussian random fields. Thereby we generalize Berry's isotropic random wave model by incorporating confinement effects through classical paths reflected at the boundaries. Our approach allows to explicitly calculate highly non-trivial statistics, such as intensity distributions, in terms of usually few short orbits, depending on the energy window considered. We compare with numerical quantum results for the Africa billiard and derive non-isotropic random wave models for other prominent confinement geometries.Comment: To be submitted to Physical Review Letter

The Precursors and Products of Justice Climates: Group Leader Antecedents and Employee Attitudinal Consequences

Drawing on the organizational justice, organizational climate, leadership and personality, and social comparison theory literatures, we develop hypotheses about the effects of leader personality on the development of three types of justice climates (e.g., procedural, interpersonal, and informational), and the moderating effects of these climates on individual level justice- attitude relationships. Largely consistent with the theoretically-derived hypotheses, the results showed that leader (a) agreeableness was positively related to procedural, interpersonal and informational justice climates, (b) conscientiousness was positively related to a procedural justice climate, and (c) neuroticism was negatively related to all three types of justice climates. Further, consistent with social comparison theory, multilevel data analyses revealed that the relationship between individual justice perceptions and job attitudes (e.g., job satisfaction, commitment) was moderated by justice climate such that the relationships were stronger when justice climate was high

Using self-definition to predict the influence of procedural justice on organizational, interpersonal, and job/task-oriented citizenship behaviors

An integrative self-definition model is proposed to improve our understanding of how procedural justice affects different outcome modalities in organizational behavior. Specifically, it is examined whether the strength of different levels of self-definition (collective, relational, and individual) each uniquely interact with procedural justice to predict organizational, interpersonal, and job/task-oriented citizenship behaviors, respectively. Results from experimental and (both single and multisource) field data consistently revealed stronger procedural justice effects (1) on organizational-oriented citizenship behavior among those who define themselves strongly in terms of organizational characteristics, (2) on interpersonal-oriented citizenship behavior among those who define themselves strongly in terms of their interpersonal relationships, and (3) on job/task-oriented citizenship behavior among those who define themselves weakly in terms of their distinctiveness or uniqueness. We discuss the relevance of these results with respect to how employees can be motivated most effectively in organizational settings

Localization of Eigenfunctions in the Stadium Billiard

We present a systematic survey of scarring and symmetry effects in the stadium billiard. The localization of individual eigenfunctions in Husimi phase space is studied first, and it is demonstrated that on average there is more localization than can be accounted for on the basis of random-matrix theory, even after removal of bouncing-ball states and visible scars. A major point of the paper is that symmetry considerations, including parity and time-reversal symmetries, enter to influence the total amount of localization. The properties of the local density of states spectrum are also investigated, as a function of phase space location. Aside from the bouncing-ball region of phase space, excess localization of the spectrum is found on short periodic orbits and along certain symmetry-related lines; the origin of all these sources of localization is discussed quantitatively and comparison is made with analytical predictions. Scarring is observed to be present in all the energy ranges considered. In light of these results the excess localization in individual eigenstates is interpreted as being primarily due to symmetry effects; another source of excess localization, scarring by multiple unstable periodic orbits, is smaller by a factor of $\sqrt{\hbar}$.Comment: 31 pages, including 10 figure

A realistic example of chaotic tunneling: The hydrogen atom in parallel static electric and magnetic fields

Statistics of tunneling rates in the presence of chaotic classical dynamics is discussed on a realistic example: a hydrogen atom placed in parallel uniform static electric and magnetic fields, where tunneling is followed by ionization along the fields direction. Depending on the magnetic quantum number, one may observe either a standard Porter-Thomas distribution of tunneling rates or, for strong scarring by a periodic orbit parallel to the external fields, strong deviations from it. For the latter case, a simple model based on random matrix theory gives the correct distribution.Comment: Submitted to Phys. Rev.

Omnidirectional broadband insulating device for flexural waves in thin plates

This work presents a gradient index device for insulating from vibrations a circular area of a thin plate. The gradient of the refractive index is achieved exploiting the thickness-dependence of the dispersion relation of flexural waves in thin plates. A well-like thickness profile in an annular region of the plate is used to mimic the combination of an attractive and repulsive potentials, focusing waves at its bottom and dissipating them by means of an absorptive layer placed on top. The central area is therefore isolated from vibrations, while they are dissipated at the bottom of the well. Simulations have been done using the multilayer multiple scattering method and the results prove their broadband efficiency and omnidirectional properties.This work has been supported by the U.S. Office of Naval Research under Grant No. N000140910554.Climente Alarcón, A.; Torrent Martí, D.; Sánchez-Dehesa Moreno-Cid, J. (2013). Omnidirectional broadband insulating device for flexural waves in thin plates. Journal of Applied Physics. 114(21):214903-214912. https://doi.org/10.1063/1.4839375S21490321491211421Hsu, J.-C., & Wu, T.-T. (2006). Efficient formulation for band-structure calculations of two-dimensional phononic-crystal plates. Physical Review B, 74(14). doi:10.1103/physrevb.74.144303McPhedran, R. C., Movchan, A. B., & Movchan, N. V. (2009). Platonic crystals: Bloch bands, neutrality and defects. Mechanics of Materials, 41(4), 356-363. doi:10.1016/j.mechmat.2009.01.005Farhat, M., Guenneau, S., Enoch, S., Movchan, A. B., & Petursson, G. G. (2010). Focussing bending waves via negative refraction in perforated thin plates. Applied Physics Letters, 96(8), 081909. doi:10.1063/1.3327813Pierre, J., Boyko, O., Belliard, L., Vasseur, J. O., & Bonello, B. (2010). Negative refraction of zero order flexural Lamb waves through a two-dimensional phononic crystal. Applied Physics Letters, 97(12), 121919. doi:10.1063/1.3491290Wu, T.-T., Chen, Y.-T., Sun, J.-H., Lin, S.-C. S., & Huang, T. J. (2011). Focusing of the lowest antisymmetric Lamb wave in a gradient-index phononic crystal plate. Applied Physics Letters, 98(17), 171911. doi:10.1063/1.3583660Farhat, M., Guenneau, S., & Enoch, S. (2010). High directivity and confinement of flexural waves through ultra-refraction in thin perforated plates. EPL (Europhysics Letters), 91(5), 54003. doi:10.1209/0295-5075/91/54003Oudich, M., Li, Y., Assouar, B. M., & Hou, Z. (2010). A sonic band gap based on the locally resonant phononic plates with stubs. New Journal of Physics, 12(8), 083049. doi:10.1088/1367-2630/12/8/083049Xiao, Y., Wen, J., & Wen, X. (2012). Flexural wave band gaps in locally resonant thin plates with periodically attached spring–mass resonators. Journal of Physics D: Applied Physics, 45(19), 195401. doi:10.1088/0022-3727/45/19/195401Torrent, D., Mayou, D., & Sánchez-Dehesa, J. (2013). Elastic analog of graphene: Dirac cones and edge states for flexural waves in thin plates. Physical Review B, 87(11). doi:10.1103/physrevb.87.115143Farhat, M., Guenneau, S., Enoch, S., & Movchan, A. B. (2009). Cloaking bending waves propagating in thin elastic plates. Physical Review B, 79(3). doi:10.1103/physrevb.79.033102Farhat, M., Guenneau, S., & Enoch, S. (2009). Ultrabroadband Elastic Cloaking in Thin Plates. Physical Review Letters, 103(2). doi:10.1103/physrevlett.103.024301Stenger, N., Wilhelm, M., & Wegener, M. (2012). Experiments on Elastic Cloaking in Thin Plates. Physical Review Letters, 108(1). doi:10.1103/physrevlett.108.014301Bramhavar, S., Prada, C., Maznev, A. A., Every, A. G., Norris, T. B., & Murray, T. W. (2011). Negative refraction and focusing of elastic Lamb waves at an interface. Physical Review B, 83(1). doi:10.1103/physrevb.83.014106Krylov, V. V., & Tilman, F. J. B. S. (2004). Acoustic ‘black holes’ for flexural waves as effective vibration dampers. Journal of Sound and Vibration, 274(3-5), 605-619. doi:10.1016/j.jsv.2003.05.010Krylov, V. V., & Winward, R. E. T. B. (2007). Experimental investigation of the acoustic black hole effect for flexural waves in tapered plates. Journal of Sound and Vibration, 300(1-2), 43-49. doi:10.1016/j.jsv.2006.07.035O’Boy, D. J., Krylov, V. V., & Kralovic, V. (2010). Damping of flexural vibrations in rectangular plates using the acoustic black hole effect. Journal of Sound and Vibration, 329(22), 4672-4688. doi:10.1016/j.jsv.2010.05.019Georgiev, V. B., Cuenca, J., Gautier, F., Simon, L., & Krylov, V. V. (2011). Damping of structural vibrations in beams and elliptical plates using the acoustic black hole effect. Journal of Sound and Vibration, 330(11), 2497-2508. doi:10.1016/j.jsv.2010.12.001D. Ross, E. E. Ungar, and E. Kerwin, in Proceedings of Structural Damping, Section 3, edited by J. E. Ruzicka (1959), pp. 49–87.O’Boy, D. J., & Krylov, V. V. (2011). Damping of flexural vibrations in circular plates with tapered central holes. Journal of Sound and Vibration, 330(10), 2220-2236. doi:10.1016/j.jsv.2010.11.017Bowyer, E. P., O’Boy, D. J., Krylov, V. V., & Horner, J. L. (2012). Effect of geometrical and material imperfections on damping flexural vibrations in plates with attached wedges of power law profile. Applied Acoustics, 73(5), 514-523. doi:10.1016/j.apacoust.2011.12.010Bowyer, E. P., O’Boy, D. J., Krylov, V. V., & Gautier, F. (2013). Experimental investigation of damping flexural vibrations in plates containing tapered indentations of power-law profile. Applied Acoustics, 74(4), 553-560. doi:10.1016/j.apacoust.2012.10.004V. Krylov, in Proceedings of the International Conference on Noise and Vibration Engineering (ISMA), edited by P. Sas, D. Moens, and S. Jonckheer (2012), pp. 933–944.Narimanov, E. E., & Kildishev, A. V. (2009). Optical black hole: Broadband omnidirectional light absorber. Applied Physics Letters, 95(4), 041106. doi:10.1063/1.3184594Climente, A., Torrent, D., & Sánchez-Dehesa, J. (2012). Omnidirectional broadband acoustic absorber based on metamaterials. Applied Physics Letters, 100(14), 144103. doi:10.1063/1.3701611Cai, L.-W., & Sánchez-Dehesa, J. (2008). Acoustical scattering by radially stratified scatterers. The Journal of the Acoustical Society of America, 124(5), 2715-2726. doi:10.1121/1.2967825Norris, A. N., & Vemula, C. (1995). Scattering of flexural waves on thin plates. Journal of Sound and Vibration, 181(1), 115-125. doi:10.1006/jsvi.1995.012

Scarring Effects on Tunneling in Chaotic Double-Well Potentials

The connection between scarring and tunneling in chaotic double-well potentials is studied in detail through the distribution of level splittings. The mean level splitting is found to have oscillations as a function of energy, as expected if scarring plays a role in determining the size of the splittings, and the spacing between peaks is observed to be periodic of period {$2\pi\hbar$} in action. Moreover, the size of the oscillations is directly correlated with the strength of scarring. These results are interpreted within the theoretical framework of Creagh and Whelan. The semiclassical limit and finite-{$\hbar$} effects are discussed, and connections are made with reaction rates and resonance widths in metastable wells.Comment: 22 pages, including 11 figure