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11.
We have extended photon correlation spectroscopy down to a one-nanosecond time scale, and applied it to a study of layer undulations in freestanding smectic-A films of two cyanobiphenyl liquid crystals. Temporal correlations in the intensity of scattered light reveal an interesting combination of under- and overdamped modes. The underdamped mode is accurately described by a recently calculated correlation function of the smectic layer displacement, although its frequency and damping rate exhibit stronger dispersion at large optical wave vectors than expected from current dynamical models for smectic films. 相似文献
12.
13.
Hughes MS McCarthy JE Marsh JN Arbeit JM Neumann RG Fuhrhop RW Wallace KD Znidersic DR Maurizi BN Baldwin SL Lanza GM Wickline SA 《The Journal of the Acoustical Society of America》2007,121(6):3542-3557
Qualitative and quantitative properties of the finite part, H(f), of the Shannon entropy of a continuous waveform f(t) in the continuum limit are derived in order to illuminate its use for waveform characterization. Simple upper and lower bounds on H(f), based on features of f(t), are defined. Quantitative criteria for a priori estimation of the average-case variation of H(f) and log E(f), where E(f) is the signal energy of f(t) are also derived. These provide relative sensitivity estimates that could be used to prospectively choose optimal imaging strategies in real-time ultrasonic imaging machines, where system bandwidth is often pushed to its limits. To demonstrate the utility of these sensitivity relations for this application, a study designed to assess the feasibility of identification of angiogenic neovasculature targeted with perfluorocarbon nanoparticles that specifically bind to alpha(v)beta3-integrin expression in tumors was performed. The outcome of this study agrees with the prospective sensitivity estimates that were used for the two receivers. Moreover, these data demonstrate the ability of entropy-based signal receivers when used in conjunction with targeted nanoparticles to elucidate the presence of alpha(v)beta3 integrins in primordial neovasculature, particularly in acoustically unfavorable environments. 相似文献
14.
A straightforward method of generating tunable coherent VUV radiation is described. Radiation down to 1362 Å was produced by Raman shifting the output of a commercially produced, excimer-pumped dye laser system. It is shown that generation of VUV radiation at 1640 Å is more efficient using the 8th anti-Stokes line from a UV dye than by using the 10th anti-Stokes line from a visible dye which had twice the output power. 相似文献
15.
E. G. Fu Y. Q. Wang G. F. Zou J. Xiong M. J. Zhuo Q. M. Wei J. K. Baldwin Q. X. Jia L. Shao A. Misra M. Nastasi 《Applied Physics A: Materials Science & Processing》2012,108(1):121-126
We studied the effect of irradiation on small angle grain boundaries in mosaic structured Cu thin films. The films showed a decrease in mosaic spread via a narrowing of the full width at half maximum in XRD rocking curves and a smaller minimum yield of RBS channeling after irradiation. These data indicate the irradiation decreased the misorientation angles between mosaic blocks separated by small angle grain boundaries. Mechanisms involving interactions between grain boundary dislocations and irradiation induced defects are discussed. 相似文献
16.
R. R. Du W. Pan H. L. Stormer D. C. Tsui L. N. Pfeiffer K. W. Baldwin K. W. West 《Physica E: Low-dimensional Systems and Nanostructures》2000,6(1-4)
Low-temperature, electronic transport in higher Landau levels (N>1) in a two-dimensional electron system is strongly anisotropic. At half-filling of either spin level of such Landau levels (
etc.) the magnetoresistance either collapses to form a deep minimum or is peaked in a sharp maximum, depending on the in-plane current direction. The anisotropic axis can be reoriented by applying an in-plane magnetic field of 1–2 T strength. The magnetoresistance at
and
(N=1) is initially isotropic but an in-plane field induces a strong anisotropy. Our observations are strong evidence for a new many-electron phase in higher Landau levels, which forms spontaneously or can be induced by an in-plane field. 相似文献
17.
Xia JS Pan W Vicente CL Adams ED Sullivan NS Stormer HL Tsui DC Pfeiffer LN Baldwin KW West KW 《Physical review letters》2004,93(17):176809
At a very low-temperature of 9 mK, electrons in the second Landau level of an extremely high-mobility two-dimensional electron system exhibit a very complex electronic behavior. With a varying filling factor, quantum liquids of different origins compete with several insulating phases leading to an irregular pattern in the transport parameters. We observe a fully developed nu=2+2/5 state separated from the even-denominator nu=2+1/2 state by an insulating phase and a nu=2+2/7 and nu=2+1/5 state surrounded by such phases. A developing plateau at nu=2+3/8 points to the existence of other even-denominator states. 相似文献
18.
19.
20.
Stewart Baldwin 《Journal of Fixed Point Theory and Applications》2010,7(1):201-222
We construct abstract Julia sets homeomorphic to Julia sets for complex polynomials of the form f
c
(z) = z
2 + c, having an associated periodic kneading sequence of the form [`(a*)]{\overline{\alpha\ast}} which is not a period n-tupling. We show that there is a single simply-defined space of “itineraries” which contains homeomorphic copies of all such
Julia sets in a natural combinatorial way, with dynamical properties which are derivable directly from the combinatorics.
This also leads to a natural definition of abstract Julia sets even for those kneading sequences which are not realized by
any polynomial f
c
, with similar dynamical properties. 相似文献