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91.
In this paper, we obtain the Varadhan type small time asymptotics for diffusion processes on path groups. 相似文献
92.
Vinay Ambegaokar 《Journal of statistical physics》2006,125(5-6):1183-1192
The time development of the reduced density matrix for a quantum oscillator damped by coupling it to an ohmic environment
is calculated via an identity of the Debye-Waller form. Results obtained some years ago by Hakim and the author in the free-particle
limit(10) are thus recovered. The evolution of a free particle in a prepared initial state is examined, and a previously published
exchange(5,9) is illuminated with figures showing no decoherence without dissipation.
PACS number: 03.75.Ss 相似文献
93.
94.
E. Sauvage N. Plucktaveesak R.H. Colby D.A. Amos B. Antalek K.M. Schroeder J.S. Tan 《Journal of polymer science. Part A, Polymer chemistry》2004,42(19):3584-3597
The dilute solution behavior of several alternating copolymers of maleic acid has been characterized by static and dynamic light scattering, intrinsic viscosity, and pulsed-gradient spin-echo NMR spectroscopy. The copolymer of maleic acid–sodium salt and isobutylene (IBMA-Na, Mw ∼350 kg/mol) dissolves readily in concentrated aqueous salt solutions. Changes in chain dimensions with ionic strength and pH are similar to those of the lesser salt solution-soluble poly(acrylic acid-sodium salt). The hydrophobically modified (with n-butyl, n-hexyl, n-octyl, and phenethyl amines) copolymers of maleic acid–sodium salts and isobutylene (IBMA-NHR-Na) show no sign of large intermolecular aggregation in 0.1 N sodium acetate (NaAc). However, the sizes of the copolymers are relatively small compared to that of the ionized parent copolymer (IBMA-Na, Mw ∼350 kg/mol), suggesting intramolecular aggregation of the alkyl side-chain groups along the polymer backbone. The copolymer modified with the longer chain n-decyl, on the other hand, forms stable large intermolecular aggregates containing 33 chains/aggregate. The copolymers of maleic acid–sodium salt and styrene (SMA-Na) appear to have no signs of aggregation, despite being a hydrophobic polyelectrolyte. The copolymer of maleic acid–sodium salt and di-isobutylene (DIBMA-Na) has a similar salting-out concentration as SMA-Na. The radius of gyration measurements by static light scattering suggest that at least some fraction of the DIBMA-Na chains form large intermolecular aggregates. The copolymers of maleic acid–sodium salt with n-alkenes (n-CmMA-Na) in 0.1 N NaAc form small intermolecular aggregates (three to five chains/aggregate). In contrast to these static light scattering results, PGSE NMR diffusion measurements for the above aggregated systems indicate only one diffusion coefficient consistent with the motion of single isolated chains. A plausible explanation for this discrepancy is that the population of the aggregates is too small to be sufficiently detected in the PGSE NMR experiment. Furthermore, it is likely that the aggregate has a larger relaxation rate than the nonaggregate, and therefore has a comparatively reduced signal in the PGSE NMR experiment. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3584–3597, 2004 相似文献
95.
Yu‐Zhong Wang 《Journal of Polymer Science.Polymer Physics》2003,41(19):2296-2301
The solubility behaviors of poly(sulfonyldiphenylene phenylphosphonate) (PSPPP), a very efficient flame retardant for poly(ethylene terephthalate) (PET), in more than 50 solvents were examined. Its solubility parameters (δ) were determined by the intrinsic viscosity and turbidic titration methods. The two methods obtained consistent results, δ = 21.0–21.6 J1/2/cm3/2 and δ = 21.0 J1/2/cm3/2, and the three‐dimensional solubility parameters were δd = 18.9 J1/2/cm3/2, δp = 8.8 J1/2/cm3/2, and δh = 5.9 J1/2/cm3/2. The miscibility of PSPPP with PET was estimated by the calculation of the heats of mixing, which were related to the difference between the solubility parameters of PSPPP and PET. Fourier transform infrared was used to examine the interactions between PSPPP and PET macromolecules, which were the internal factors of polymer–polymer miscibility. The results showed that PSPPP and PET were miscible within a very wide composition range, especially with less than 15 wt % PSPPP, a composition of interest for the preparation of flame‐retardant PET. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2296–2301, 2003 相似文献
96.
On the Asymptotic Stability of the Intrinsic and Fractional Bayes Factors for Testing Some Diffusion Models 总被引:1,自引:0,他引:1
S. Sivaganesan Rama T. Lingham 《Annals of the Institute of Statistical Mathematics》2002,54(3):500-516
Random processes, from which a single sample path data are available on a fine time scale, abound in many areas including finance and genetics. An effective way to model such data is to consider a suitable continuous-time-scale analog, X
t say, for the underlying process. We consider three diffusion models for the process X
t and address model selection under improper priors. Specifically, fractional and intrinsic Bayes factors (FBF and IBF) for model selection are considered. Here, we focus on the asymptotic stability of the IBF's and FBF's for comparing these models. Specifically, we propose to employ certain novel transformations of the data in order to ensure the asymptotic stability of the IBF's. While we use different transformations for pairwise comparisons of the models, we also show that a single common transformation can be used when simultaneously comparing all three models. We then demonstrate that, when FBF's are used to compare these models, we may have to employ different, model-specific training fractions in order to achieve asymptotic stability of the FBF's. 相似文献
97.
区间数的标准表示及其四则运算法则与泛灰数的内在联系 总被引:2,自引:0,他引:2
在回顾泛灰数四则运算法则基础上,给出了区间数的标准表示,论述了标准区间数的四则运算法则与泛灰数的内在联系及其应用前景. 相似文献
98.
We study the influence of intrinsic decoherence in the presence of Stark shift for the two-mode Jaynes—Cummings model (JCM). An analytic solution of the Milburn equation for the multiquant two-mode JCM Hamiltonian is obtained. We use this solution to investigate the influence of intrinsic decoherence and Stark shift on nonclassical properties of the system, for the resonant and the off-resonant cases. We compare the behavior of the system in the case of having a coherent superposition state and a statistical mixture of coherent states as an initial field. 相似文献
99.
Akikazu Matsumoto Sachiyo Umehara Hiroyuki Watanabe Takayuki Otsu 《Journal of Polymer Science.Polymer Physics》1993,31(5):527-535
Poly(N-n-butylitaconimide) was prepared by radical polymerization in benzene and in bulk at 60°C and was subsequently fractionated at 30°C with benzene and methanol as solvent and nonsolvent, respectively. Relationships between molecular weight and intrinsic viscosity (Mark-Houwink-Sakurada equations) in tetrahydrofuran, benzene, and toluene at 30°C are established. From the Burchard-Stockmayer-Fixman plot, the characteristic ratio of this polymer is determined, and local chain conformation is discussed in relation to the termination process in radical polymerization. © 1993 John Wiley & Sons, Inc. 相似文献
100.
AM Jayannavar 《Pramana》2002,58(2):173-181
We present a simple model of transmission across a metallic mesoscopic ring. In one of its arm an electron interacts with
a single magnetic impurity via an exchange coupling. We show that entanglement between electron and spin impurity states leads
to reduction of Aharonov-Bohm oscillations in the transmission coefficient. The spin-conductance is asymmetric in the flux
reversal as opposed to the two-probe electrical conductance which is symmetric. In the same model, in contradiction to the
naive expectation of a current magnification effect, we observe enhancement as well as suppression of this effect depending
on the system parameters. The limitations of this model to the general notion of dephasing or decoherence in quantum systems
are pointed out. 相似文献