Relaxation intensity in some polyacrylates

Empirical formula suggested by Kita and Koizumi for evaluation of relaxation intensity in a limited range of frequency around the relaxation frequency for the Cole-Cole type distribution has been tested for poly butyl acrylate (PBA), Poly butyl methacrylate (PBMA) and poly isobutyl methacrylate (PiBMA). The relaxation intensity Δε is expressed in terms ofε″ _M , the dielectric loss maxima andW, the frequency separation for half, two thirds or three quarters ofε″ _M , in the form Δε=ε″ _M /[(C ₁/W)+C ₂+C ₃ W], where the numerical constantsC ₁,C ₂,C ₃ are given for the respective type of relaxation.     

Topologically protected qubits from a possible non-Abelian fractional quantum Hall state

The Pfaffian state is an attractive candidate for the observed quantized Hall plateau at a Landau-level filling fraction nu=5/2. This is particularly intriguing because this state has unusual topological properties, including quasiparticle excitations with non-Abelian braiding statistics. In order to determine the nature of the nu=5/2 state, one must measure the quasiparticle braiding statistics. Here, we propose an experiment which can simultaneously determine the braiding statistics of quasiparticle excitations and, if they prove to be non-Abelian, produce a topologically protected qubit on which a logical Not operation is performed by quasiparticle braiding. Using the measured excitation gap at nu=5/2, we estimate the error rate to be 10(-30) or lower.     

Line of critical points in 2+1 dimensions: quantum critical loop gases and non-Abelian gauge theory

In this Letter, we (1) construct a one-parameter family of lattice models of interacting spins; (2) obtain their exact ground states; (3) derive a statistical-mechanical analogy which relates their ground states to O(n) loop gases; (4) show that the models are critical for d相似文献   

On the approximation of periodic solutions of equations with bounded nonlinearities

We present a method for obtaining a closed-form approximation to harmonic periodic solutions of a class of ordinary differential equations containing a bounded, Lipschitzian nonlinearity and a sinusoidal forcing term. Our technique replaces the continuous nonlinearity with a suitable step-function nonlinearity and uses the Phase-Shift-Averaging Method to write the solution of the piecewise-linear problem in closed form.     

Sharp signature of a dx2-y2 quantum critical point in the Hall coefficient of cuprate superconductors

We study the behavior of the Hall coefficient, R(H), in a system exhibiting dx(2)(-y(2)) density-wave order in a regime in which the carrier concentration, x, is tuned to approach a quantum critical point at which the order is destroyed. At the mean-field level, we find that n(Hall)=1/R(H) evinces a sharp signature of the transition. There is a kink in n(Hall) at the critical value of the carrier concentration, x(c); as the critical point is approached from the ordered side, the slope of n(Hall) diverges. Hall transport experiments in the cuprates, at high magnetic fields sufficient to destroy superconductivity, should reveal this effect.     

Raman spectral signatures of mouse mammary tissue and associated lymph nodes: normal,tumor and mastitis

Raman spectroscopy involves the interaction of light with the molecular vibrations and therefore can provide information about molecular structure, tissue composition and changes in its environment. We explored whether Raman spectroscopy can reliably distinguish mammary tumors from normal mammary tissues and other pathological states in mice. We analyzed a large number of Raman spectra from the tumor and normal mammary glands of mice injected with 4T1 tumor cells, which were collected using a high‐resolution (less than 4 cm⁻¹) Raman spectrometer at a fixed (785 nm) laser excitation wavelength and with 60 mW of laser power. The spectra of normal and tumor mammary glands showed consistent differences in the intensity of certain Raman bands and loss of some bands in the tumor spectra. Multivariate statistical methods—principal component analysis (PCA) and discriminant functional analysis (DFA)—were used to separate the data into different groups of mammary tumors, mastitis, lymph nodes contralateral and tumor‐cell‐injected sides, and normal contralateral and tumor‐cell‐injected sides. We demonstrate that this spectroscopic technique has the feasibility of discriminating tumor and mastitis from normal tissues and other pathological states in a short period of time and may detect tumor transformation earlier than the standard histological examination stage. Copyright © 2006 John Wiley & Sons, Ltd.     

A robust method for automated background subtraction of tissue fluorescence

This paper introduces a new robust method for the removal of background tissue fluorescence from Raman spectra. Raman spectra consist of noise, fluorescence and Raman scattering. In order to extract the Raman scattering, both noise and background fluorescence must be removed, ideally without human intervention and preserving the original data. We describe the rationale behind our robust background subtraction method, determine the parameters of the method and validate it using a Raman phantom against other methods currently used. We also statistically compare the methods using the residual mean square (RMS) with a fluorescence‐to‐signal (F/S) ratio ranging from 0.1 to 1000. The method, ‘adaptive minmax’, chooses the subtraction method based on the F/S ratio. It uses multiple fits of different orders to maximize each polynomial fit. The results show that the adaptive minmax method was significantly better than any single polynomial fit across all F/S ratios. This method can be implemented as part of a modular automated real‐time diagnostic in vivo Raman system. Copyright © 2007 John Wiley & Sons, Ltd.     

Morphology controlled open circuit voltage in polymer solar cells

We report a strong dependence of open circuit voltage on the altered morphology of block copolymer (P3HT‐b ‐PPerAcr) based solar cells. The open circuit voltage increases dramatically by about 300 mV by increasing the amount of acceptor homopolymer within the block copolymer/homopolymer blends. The change in open circuit voltage is found to be in correlation with the enrichment of acceptor moiety at the film surface as identified by Atomic force microscopy (AFM) and X‐ray photoelectron spectroscopy (XPS). Based on this fact, an additional increase in open circuit voltage to its maximum values is achieved by introducing an acceptor buffer layer at the cathode interface. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)