Computer extended series solution for unsteady flow in a contracting or expanding pipe

Unsteady flow in a semi-infinite contracting or expanding pipeis reinvestigated using long series analysis. The proposed seriesmethod is useful in analysing the problem for a moderately largeconstant ( = aa/, where a = a(t), the radius of the pipe isa function of time, a(t) is the velocity of the wall, and iskinematic viscosity). For positive values of (expansion ofthe pipe) accuracy of the series representing shear stress andpressure gradient is increased from = 2.89 to = 6.0 by extractingthe singularity followed by completion of the series. For negativevalues of (contraction of the pipe), we revert the series whichresults into the increase of the region of validity of the transposedseries from = -25.0 to = -2.89. Later we use Padé approximantsfor summing them. Also, the asymptotic solution for large valuesof is obtained and it agrees closely with pure numerical valuesof shear stress at the wall and pressure gradient.     

A semi-Markov model of disease recurrence in insured dogs

We use a semi-Markov model to analyse the stochastic dynamics of disease occurrence of dogs insured in Canada from 1990 to 1999, and the probability pattern of death from illness. After statistically justifying the use of a stochastic model, we demonstrate that a stationary first-order semi-Markov process is appropriate for analysing the available data set. The probability transition function is estimated and its stationarity is tested statistically. Homogeneity of the semi-Markov model with respect to important covariates (such as geographic location, insurance plan, breed and age) is also statistically examined. We conclude with discussions and implications of our results in veterinary contents. Copyright © 2007 John Wiley & Sons, Ltd.     

Reactions of elemental phoshorus and phosphine with electrophiles in superbasic systems: XIX. Formation of the C-P bond with participation of elemental phosphorus under microwave assistance

Microwave irradiation facilitates phosphorylation of aryl methyl chlorides and styrene with red phosphorus in the presence of strong bases and increases the yield of the main products, tertiary phosphine oxides.     

Low-frequency static characterization of microstructures using acousto-optic modulated stroboscopic interferometer

Micro-electro-mechanical-systems (MEMS) structures such as microcantilevers, micromirrors, accelerometers, gyroscopes, and filters are some of the new types of integrated electro-mechanical microstructures in need of testing tools to measure precisely their static and dynamic properties. The acousto-optic-modulated-stroboscopic-interferometer (AOMSI) is an innovative tool that can be employed to investigate the above-mentioned characteristics for a given environmental condition. In this work, an optical non-contact system employing an acousto-optic-modulator (AOM) to conduct low frequency static characterization of MEMS microstructures is presented. The method is applied to a silicon-on-insulator (SOI) cantilever for demonstration purposes. The theoretical analysis is based on an energy approach. Experimental results are presented and compared with the theory, and are found to be in good agreement.     

Banach 空间二阶积-微分方程组初值问题

该文利用新的比较结果研究Banach 空间二阶积-微分方程组初值问题解的存在性.即使在有限维空间, 其结果也是新的.     

Suppression of primary chromatic aberration by genetic algorithm in an advanced telephoto lens

This paper proposes a new method for finding a suitable glass combination set for an advanced telephoto lens via a genetic algorithm (GA). Normally, glass properties, inclusive of index and Abbe number, play a significant role in the elimination of primary chromatic aberration. So many optical glasses (over 300 different refractive types) have been developed hitherto that it is difficult to choose a state-of-the-art glass combination quickly. According to the newly developed GA operations in this paper, however, several suitable glass combinations can be found quickly through a unique sequence of function selection, crossover and mutation. An advanced telephoto lens design is employed in this research, which has the characteristic of being more sensitive to axial aberrations than lateral chromatic aberrations. The GA operations are described in the macro of the optical software program, CODE V. The simulation results in this research show that the primary chromatic aberration is efficiently eliminated after the application of GA. The main goal of this research is that during optimization, error function could be minimized only if primary aberrations are well under control in our first step; in a telephoto lens, the secondary spectrum of longitudinal chromatic aberration and lateral chromatic aberration caused by distortion play a role in chromatic aberration control as well; however, optimization with a combination of both primary chromatic aberration and secondary chromatic aberration will complicate the process with a lot of working variables. The GA method introduced in this paper might efficiently eliminate the primary chromatic aberration first by finding the best glass combination and its trend and then simplifying the following optimization process for all optical systems.     

Fine structure in the azimuthal transverse momentum correlations at $\sqrt{s_{NN}}=200$ GeV using the event shape analysis

The experimental results on transverse momentum azimuthal hadron correlations at RHIC have opened a rich field for parton energy loss analysis in heavy-ion collisions. Recently, a considerable amount of work has been devoted to study the shapes of the “away-side” jet which exhibit an interesting and unexpected “double hump” structure not observed in the analogous treatment of the pp data. Driven by the possibility that the latter result might just mean that such a structure exists already in the case of pp collisions, but that its relative intensity could be small, here we use the Event Shape Analysis to show that it is possible to identify and select well defined event topologies in pp collisions, among which a double hump structure for the away-side jet emerges. Using two shape parameters, the sphericity in the transverse plane and the recoil to analyze a sample of PYTHIA generated pp collisions at  GeV, we show that this structure corresponds to two jets emitted in the backward hemisphere. Finally, we show that Q-PYTHIA qualitatively reproduces the decrease in the yield of dijet events and the increase of the double hump structure in the away side observed in heavy-ion collisions. The implications for the treatment of parton energy loss in heavy-ion collisions are discussed.     

Quantum hysteresis loops in microscopic system: The loop area as a dynamical parameter

The area enclosed by hysteresis loops in a periodically forced bistable microscopic system at zero-temperature is examined by using the time dependent Hellmann-Feynman theorem and the Fourier grid Hamiltonian recipe for solving time-dependent Schrödinger equation. Effects of non-zero temperatures are explored with reference to a symmetric double well potential. The barrier crossing or, relaxation rates are shown to correlate systematically with the area of the loop. The possible use of hysteresis loop area in designing field parameters for optimal control is suggested.     

Reconfigurable Bioinspired Framework Nucleic Acid Nanoplatform Dynamically Manipulated in Living Cells for Subcellular Imaging

In nature, the formation of spider silk fibers begins with dimerizing the pH‐sensitive N‐terminal domains of silk proteins (spidroins) upon lowering pH, and provides a natural masterpiece for programmable assembly. Inspired by the similarity of pH‐dependent dimerization behaviors, introduced here is an i‐motif‐guided model to mimic the initial step of spidroin assembly at the subcellular level. A framework nucleic acid (FNA) nanoplatform is designed using two tetrahedral DNA nanostructures (TDNs) with different branched vertexes carrying a bimolecular i‐motif and a split ATP aptamer. Once TDNs enter acidic lysosomes within living cells, they assemble into a heterodimeric architecture, thereby enabling the formation of a larger‐size framework and meanwhile subcellular imaging in response to endogenous ATP, which can be dynamically manipulated by adjusting intracellular pH and ATP levels with external drug stimuli.