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Chaos : Improvements and applications of entrainment control for n...

By: Fang Liu, Qiang Song, and Jinde Cao

Description: This paper improves the existing entrainment control approaches and develops unified schemes to chaos control and generalized (lag, anticipated, and complete) synchronization of nonlinear dynamical systems. By introducing impulsive effects to the open-loop control method, we completely remove its restrictions on goal dynamics and initial conditions, and derive a sufficient condition to estimate the upper bound of impulsive intervals to ensure the global asym...

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Review of Scientific Instruments : Microbeam-integrated multiphoto...

By: Alan W. Bigelow, Charles R. Geard, Gerhard Randers-Pehrson, and David J. Brenner

Description: Multiphoton microscopy has been added to the array of imaging techniques at the endstation for the Microbeam II cell irradiator at Columbia University’s Radiological Research Accelerator Facility (RARAF). This three-dimensional (3D), laser-scanning microscope functions through multiphoton excitation, providing an enhanced imaging routine during radiation experiments with tissuelike samples, such as small living animals and organisms. Studies at RARAF focus o...

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Review of Scientific Instruments : A newly designed single etalon ...

By: Dukhyeon Kim, Seongok Kwon, Hyungki Cha, Younggi Kim, and Jeonghaei Sunwoo

Description: A new optical Doppler lidar receiving system which can measure Doppler-shifted incoherent scattering light has been proposed and tested. This system functions in a manner similar to two edge filters and consists of a single etalon, a polarization beam splitter, and mirrors that can guide scattered light into a single etalon with two different angles. These two incident angles are precisely adjusted by the polarization beam splitter and mirrors. Using this op...

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Applied Physics Letters : Performance comparison of Pb(Zr0.52Ti0.4...

By: Hengky Chandrahalim, Sunil A. Bhave, Ronald Polcawich, Jeff Pulskamp, Daniel Judy et al

Description: This paper provides a quantitative comparison and explores the design space of lead zirconium titanate (PZT)–only and PZT-on-silicon length-extensional mode resonators for incorporation into radio frequency microelectromechanical system filters and oscillators. We experimentally measured the correlation of motional impedance (RX) and quality factor (Q) with the resonators’ silicon layer thickness (tSi). For identical lateral dimensions and PZT-layer thicknes...

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Biblioteca Hispanica : Lessons of Natural History Accompanied by T...

By: Jose Maria Pascual
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Physics of Fluids : Flow and transport in brush-coated capillaries...

By: D. I. Dimitrov, L. I. Klushin, A. Milchev, and K. Binder

Description: We apply an efficient method of forced imbibition to (nano-)capillaries, coated internally with a polymer brush, to derive the change in permeability and suction force, corresponding to different grafting densities and lengths of the polymer chains. While the fluid is modeled by simple point particles interacting with Lennard-Jones forces, the (end-grafted, fully flexible) polymers, which form the brush coating, are described by a standard bead-spring model....

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Physics of Fluids : Evolution of neutral and charged droplets in a...

By: M. A. Fontelos, U. Kindelán, and O. Vantzos

Description: We study the evolution of drops of a very viscous and conducting fluid under the influence of an external electric field. The drops may be neutral or may be charged with some amount of electric charge. If both the external electric field and total drop charge are sufficiently small, then prolate spherical shapes develop according to Taylor’s observations. For sufficiently large charge and/or external field a self-similar conelike singularity develops in a me...

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Chaos : Stability diagram for the forced Kuramoto model

By: Lauren M. Childs and Steven H. Strogatz

Description: We analyze the periodically forced Kuramoto model. This system consists of an infinite population of phase oscillators with random intrinsic frequencies, global sinusoidal coupling, and external sinusoidal forcing. It represents an idealization of many phenomena in physics, chemistry, and biology in which mutual synchronization competes with forced synchronization. In other words, the oscillators in the population try to synchronize with one another while al...

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Physics of Fluids : Coherent flow states in a square duct

By: Håkan Wedin, Damien Biau, Alessandro Bottaro, and Masato Nagata

Description: The flow in a square duct is considered. Finite amplitude approximate traveling wave solutions, obtained using the self-sustaining-process approach introduced by Waleffe [Phys. Fluids 9, 883 (1997) ], are obtained at low to moderate Reynolds numbers and used as initial conditions in direct numerical simulations. The ensuing dynamics is analyzed in a suitably defined phase space. Only one among the traveling wave solutions found is capable of surviving for a ...

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Biblioteca Hispanica : Speech on the Importance of the Study of Na...

By: Joaquin Francisco Ballasts and Ruiz
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Applied Physics Letters : Influence of polarity on carrier transpo...

By: Yoshinobu Kawaguchi, Chia-Yen Huang, Yuh-Renn Wu, Qimin Yan, Chih-Chien Pan et al

Description: We investigate the influence of polarity on carrier transport in single-quantum-well and multiple-quantum-well (MQW) light-emitting diodes (LEDs) grown on the semipolar (20¯21) and (20¯21) orientations of free-standing GaN. For semipolar MQW LEDs with the opposite polarity to conventional Ga-polar c-plane LEDs, the polarization-related electric field in the QWs results in an additional energy barrier for carriers to escape the QWs. We show that semipolar (20...

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Review of Scientific Instruments : A time-resolved single-pass tec...

By: Jun Li, Xianming Zhou, and Jiabo Li

Description: An experimental method was developed to perform time-resolved, single-pass optical absorption measurements and to determine absorption coefficients of window materials under strong shock compression up to ∼ 200 GPa. Experimental details are described of (i) a configuration to generate an in situ dynamic, bright, optical source and (ii) a sample assembly with a lithium fluoride plate to essentially eliminate heat transfer from the hot radiator into the specim...

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Review of Scientific Instruments : A frequency-stabilized differen...

By: Wen-Ping Deng, Bo Gao, Cun-Feng Cheng, Guo-Sheng Cheng, Shui-Ming Hu et al

Description: A midinfrared laser spectrometer is built up based on the difference frequency generation (DFG) of a Nd:YAG (yttrium aluminum garnet) laser and a tunable Ti:sapphire (Ti:Sa) laser. Tuning the Ti:Sa laser and operating properly with the periodically poled lithium niobate crystal, the DFG emission is tunable in the spectral range of 2.3–5.0 μm. The 1064 nm Nd:YAG laser frequency is stabilized to the 10−6 cm−1 level on a Doppler-broadened I2 absorption line at ...

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Physics of Plasmas : Modeling of an advanced concept of a double s...

By: L. Garrigues, C. Boniface, G. J. Hagelaar, and J. P. Boeuf

Description: We present a study of the principle and operation of a two-stage Hall effect thruster, the SPT-MAG, using a two-dimensional quasineutral hybrid model coupled with a Monte Carlo simulation of electron transport. The purpose of the two-stage design is the separation of ion production and acceleration in two separate chambers, the ionization stage and the acceleration stage, with separate control of acceleration voltage and total ionization. The originality of ...

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Biblioteca Hispanica : Programme-summary of Natural History Items

By: Manuel Mir and Navarro
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The Journal of Chemical Physics : Equilibrium fluctuations of the ...

By: D. I. Zhukhovitskii

Description: Spectra of the cluster surface equilibrium fluctuations are treated by decomposition into the bulk and net capillary ones. The bulk fluctuations without capillary ones are simulated by the surface of a cluster truncated by a sphere. The bulk fluctuation spectrum is shown to be generated primarily by the discontinuity in the spatial distribution of cluster internal particles. The net capillary fluctuation slice spectrum is obtained in molecular dynamics simul...

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Chaos : Asymmetric spatiotemporal chaos induced by a polypoid mass...

By: Yu Zhang and Jack J. Jiang

Description: In this paper, asymmetric spatiotemporal chaos induced by a polypoid mass simulating the laryngeal pathology of a vocal polyp is experimentally observed using high-speed imaging in an excised larynx. Spatiotemporal analysis reveals that the normal vocal folds show spatiotemporal correlation and symmetry. Normal vocal fold vibrations are dominated mainly by the first vibratory eigenmode. However, pathological vocal folds with a polypoid mass show broken symme...

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Physics of Plasmas : Toroidal equilibria in spherical coordinates

By: K. H. Tsui

Description: The standard Grad–Shafranov equation for axisymmetric toroidal plasma equilibrium is customary expressed in cylindrical coordinates with toroidal contours, and through which benchmark equilibria are solved. An alternative approach to cast the Grad–Shafranov equation in spherical coordinates is presented. This equation, in spherical coordinates, is examined for toroidal solutions to describe low β Solovev and high β plasma equilibria in terms of elementary functions.

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Review of Scientific Instruments : Transferring cold atoms in doub...

By: Junmin Wang, Jing Wang, Shubin Yan, Tao Geng, and Tiancai Zhang

Description: A novel scheme of transferring cold atoms in a double magneto-optical trap (MOT) system has been experimentally demonstrated. Cold cesium atoms trapped in a vapor-cell MOT are efficiently transferred to an ultrahigh-vacuum (UHV) MOT by a continuous-wave divergent Gaussian transfer laser beam. When large red detuning and moderate intensity are adopted for the transfer laser beam, enhancement of the recapturing of atoms in the UHV MOT is clearly observed. Usin...

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Biblioteca Hispanica : Assay Course of Natural History Paintings

By: Emilio Ribera Gomez
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