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101.
102.
Niels Brene 《Nuclear Physics B》1973,65(2):307-318
With the construction of high energy, high intensity accelerators (NAL & CERN, SPS) investigation of neutrino scattering on virtual pions, á la Chew-Low, becomes experimentally possible. We propose to analyse the process ν + N → μ? + K + Δ to extract the usual K?3 form factor(s) for spacelike momentum transfer. A model calculation suggests that f+(T) can be determined reasonably well from a triple differential cross section, whereas only rough information on f?(T) may be obtained from the transverse polarization of the muon. The experiment proposed requires scanning of several millions of bubble chamber pictures. 相似文献
103.
Bo Jakobsen Kristine Niss Claudio Maggi Niels Boye Olsen Tage Christensen Jeppe C. Dyre 《Journal of Non》2011,357(2):267-273
The phenomenology of the beta relaxation process in the shear-mechanical response of glass-forming liquids is summarized and compared to that of the dielectric beta process. Furthermore, we discuss how to model the observations by means of standard viscoelastic modeling elements. Necessary physical requirements to such a model are outlined, and it is argued that physically relevant models must be additive in the shear compliance of the alpha and beta parts. A model based on these considerations is proposed and fitted to data for Polyisobutylene 680. 相似文献
104.
Tage Christensen Bo Jakobsen Jon Papini Tina Hecksher Jeppe C. Dyre Niels Boye Olsen 《Journal of Non》2011,357(2):346-350
In order to describe relaxation the thermodynamic coefficient can be generalized into a complex frequency-dependent cross response function. We explore theoretically the possibility of measuring for a supercooled liquid near the glass transition. This is done by placing a thermistor in the middle of the liquid which itself is contained in a spherical piezoelectric shell. The piezoelectric voltage response to a thermal power generated in the thermistor is found to be proportional to but factors pertaining to heat diffusion and adiabatic compressibility κS(ω) do also intervene. We estimate a measurable piezoelectric voltage of 1 mV to be generated at 1 Hz for a heating power of 0.3 mW. Together with κS(ω) and the longitudinal specific heat cl(ω) which may also be found in the same setup a complete triple of thermoviscoelastic response functions may be determined when supplemented with shear modulus data. 相似文献
105.
Hodgkiss JM Damrauer NH Pressé S Rosenthal J Nocera DG 《The journal of physical chemistry. B》2006,110(38):18853-18858
The temperature-isotope dependence of proton-coupled electron transfer (PCET) for a noncovalent molecular dyad is reported. The system consists of an excited-state Zn(II) porphyrin that transfers an electron to a naphthalene diimide acceptor through an amidinium-carboxylate interface. Two different isotope effects are observed for variant temperature regimes. A reverse isotope effect (i.e., kH/kD < 1) is observed as T approaches 120 K (kH/kD = 0.9, 120 K), whereas a normal isotope effect (i.e., kH/kD > 1) is recovered as the temperature is increased (kH/kD = 1.2, 300 K). The transition between these limits is smooth, with a crossover temperature of T approximately 160 K. These observations are in accordance with charge-transfer dynamics that are susceptible to bath-induced fluctuations in the proton coordinate. 相似文献
106.
107.
Jin-Long Chen Yuo-Hsien Shiau Hung-Wen Chiu Niels Wessel Jürgen Kurths Woei-Chyn Chu 《Physica A》2010,389(9):1861-1868
Despite many previous studies on the association between hyperthyroidism and the hyperadrenergic state, controversies still exist. Detrended fluctuation analysis (DFA) is a well recognized method in the nonlinear analysis of heart rate variability (HRV), and it has physiological significance related to the autonomic nervous system. In particular, an increased short-term scaling exponent α1 calculated from DFA is associated with both increased sympathetic activity and decreased vagal activity. No study has investigated the DFA of HRV in hyperthyroidism. This study was designed to assess the sympathovagal balance in hyperthyroidism. We performed the DFA along with the linear analysis of HRV in 36 hyperthyroid Graves’ disease patients (32 females and 4 males; age 30 ± 1 years, means ± SE) and 36 normal controls matched by sex, age and body mass index. Compared with the normal controls, the hyperthyroid patients revealed a significant increase (P<0.001) in α1 (hyperthyroid 1.28±0.04 versus control 0.91±0.02), long-term scaling exponent , overall scaling exponent , low frequency power in normalized units (LF%) and the ratio of low frequency power to high frequency power (LF/HF); and a significant decrease (P<0.001) in the standard deviation of the R-R intervals (SDNN) and high frequency power (HF). In conclusion, hyperthyroidism is characterized by concurrent sympathetic activation and vagal withdrawal. This sympathovagal imbalance state in hyperthyroidism helps to explain the higher prevalence of atrial fibrillation and exercise intolerance among hyperthyroid patients. 相似文献
108.
Niels van der Laan Ward Romeijnders Maarten H. van der Vlerk 《Computational Management Science》2018,15(3-4):325-349
We derive bounds on the expectation of a class of periodic functions using the total variations of higher-order derivatives of the underlying probability density function. These bounds are a strict improvement over those of Romeijnders et al. (Math Program 157:3–46, 2016b), and we use them to derive error bounds for convex approximations of simple integer recourse models. In fact, we obtain a hierarchy of error bounds that become tighter if the total variations of additional higher-order derivatives are taken into account. Moreover, each error bound decreases if these total variations become smaller. The improved bounds may be used to derive tighter error bounds for convex approximations of more general recourse models involving integer decision variables. 相似文献
109.
Niels Schwartz 《Mathematische Nachrichten》2010,283(5):758-774
The relationship between a poring and a convex subring has been studied most successfully for porings with bounded inversion. The best conceivable results are known for real closed rings. The present paper focuses on the connections between the prime spectra and between the real spectra of a poring and a convex subring. Examples show that for arbitrary porings one may not expect a very close relationship. But with the assumption of bounded inversion or spectral compatibility the results are similar to those for real closed rings (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
110.
In this paper, we study the initial value problem for a class of non-linear stochastic equations of Burgers type of the following form for u:(t,x)∈(0,∞)×R?u(t,x)∈R, where q(x,D) is a pseudo-differential operator with negative definite symbol of variable order which generates a stable-like process with transition density, f,h1,h2:[0,∞)×R×R→R are measurable functions, and Ft,x stands for a Lévy space-time white noise. We investigate the stochastic equation on the whole space R in the mild formulation and show the existence of a unique local mild solution to the initial value problem by utilising a fixed point argument. 相似文献
∂tu+q(x,D)u+∂xf(t,x,u)=h1(t,x,u)+h2(t,x,u)Ft,x