Model-free

Lipari G and Szabo A 1982 Model-free approach to the interpretation of nuclear magnetic resonance relaxation in macromolecules 1. Theory and range of validity J. Am. Chem. Soc. 104 4546-59... 

Hayward, S., Kitao, A., Berendsen, H.J.C. Model-free methods to analyze domain motions in proteins from simulation A comparison of normal mode analysis and molecular dynamics simulation of lysozyme. Proteins 27 (1997) 425-437. 

Four Challenges in IVIoSecula Modelling Free Energies, Solvation, Reactions and Solid-state Defects... 

Figure 5.8 The finite element mesh used to model free surface flow in example 5.2.1...

Recently, first-principle calculations have been reported on model-free TXRF of stratified structures [4.61]. 

Another way to describe deviations from the simple BPP spectral density is the so-called model-free approach of Lipari and Szabo [10]. This takes account of the reduction of the spectral density usually observed in NMR relaxation experiments. Although the model-free approach was first applied mainly to the interpretation of relaxation data of macromolecules, it is now also used for fast internal dynamics of small and middle-sized molecules. For very fast internal motions the spectral density is given by ... 

In spite of the absence of periodicity, glasses exhibit, among other things, a specific volume, interatomic distances, coordination number, and local elastic modulus comparable to those of crystals. Therefore it has been considered natural to consider amorphous lattices as nearly periodic with the disorder treated as a perturbation, oftentimes in the form of defects, so such a study is not futile. This is indeed a sensible approach, as even the crystals themselves are rarely perfect, and many of their useful mechanical and other properties are determined by the existence and mobility of some sort of defects as well as by interaction between those defects. Nevertheless, a number of low-temperamre phenomena in glasses have persistently evaded a microscopic model-free description along those lines. A more radical revision of the concept of an elementary excitation on top of a unique ground state is necessary [3-5]. 

H. Gampp, M. Maeder, C.J. Meyer and A.D. Zuberbuhler, Calculation of equilibrium constants from multiwavelength spectroscopic data. Ill Model-free analysis of spectrophotometric and ESR titrations. Talanta, 32 (1985) 1133-1139. 

Adamo, C., Barone, V., 1997, Toward Reliable Adiabatic Connection Models Free from Adjustable Parameters , Chem. Phys. Lett., 274, 242. 

Niosomes (prepared using surfactant I and surfactant I, II, or III and 30% cholesterol) containing stibogluconate have been as effective as the corresponding liposomal drugs in the visceral leishmaniasis model. Free drug showed reduced efficacy [169],... 

In this contribution we will deal with electron-electron correlation in solids and how to learn about these by means of inelastic X-ray scattering both in the regime of small and large momentum transfer. We will compare the predictions of simple models (free electron gas, jellium model) and more sophisticated ones (calculations using the self-energy influenced spectral weight function) to experimental results. In a last step, lattice effects will be included in the theoretical treatment. 

Papoular, R.J. and Delapalme, A. (1994) Model-free polarised neutron diffraction study of an acentric crystal metamagnetic UCoAl, Phys. Rev. Lett., 72(10), 1486-1489. 

Combined use of Eqs. (43)—(45) allows free drug concentrations to be predicted for each subcompartment. This approach to modeling free drug concentrations would make use of protein binding parameters (i.e., Bt, Kt) obtained from in vitro experiments. 

ANNs need supervised learning schemes and can so be applied for both classification and calibration. Because ANNs are nonlinear and model-free approaches, they are of special interest in calibration. 

For folded proteins, relaxation data are commonly interpreted within the framework of the model-free formalism, in which the dynamics are described by an overall rotational correlation time rm, an internal correlation time xe, and an order parameter. S 2 describing the amplitude of the internal motions (Lipari and Szabo, 1982a,b). Model-free analysis is popular because it describes molecular motions in terms of a set of intuitive physical parameters. However, the underlying assumptions of model-free analysis—that the molecule tumbles with a single isotropic correlation time and that internal motions are very much faster than overall tumbling—are of questionable validity for unfolded or partly folded proteins. Nevertheless, qualitative insights into the dynamics of unfolded states can be obtained by model-free analysis (Alexandrescu and Shortle, 1994 Buck etal., 1996 Farrow etal., 1995a). An extension of the model-free analysis to incorporate a spectral density function that assumes a distribution of correlation times on the nanosecond time scale has recently been reported (Buevich et al., 2001 Buevich and Baum, 1999) and better fits the experimental 15N relaxation data for an unfolded protein than does the conventional model-free approach. 

Another powerful tool for examining this issue is the use of time-resolved fluorescence spectra, especially when combined with the technique of Time-Resolved Area Normalized Emission Spectra (TRANES) developed by Periasamy and coworkers [78-80]. In this method, separate decay curves are collected over a wide range of emission wavelengths and reconstructed into time-resolved spectra, which are then normalized to constant area. In this model-free approach, it is possible to deduce the nature of heterogeneity of the fluorescent species from the... 

The elastic free energy of the constrained-junction model, similar to that of the slip-link model, is the sum of the phantom network free energy and that due to the constraints. Both the slip-link and the constrained-junction model free energies reduce to that of the phantom network model when the effect of entanglements diminishes to zero. One important difference between the two models, however, is that the constrained-junction model free energy equates to that of the affine network model in the limit of infinitely strong constraints, whereas the slip-link model free energy may exceed that for an affine deformation, as may be observed from Equation (41). 

A model-free method for the analysis of lattice distortions is readily established from Eq. (8.13). It is an extension of Stokes [27] method for deconvolution and has been devised by Warren and Averbach [28,29] (textbooks Warren [97], Sect. 13.4 Guinier [6], p. 241-249 Alexander [7], Chap. 7). For the application to common soft matter it is of moderate value only, because the required accuracy of beam profile measurement is rarely achievable. On the other hand, for application to advanced polymeric materials its applicability has been demonstrated [109], although the classical graphical method suffers from extensive approximations that reduce its value for the typical polymer with small crystal sizes and stronger distortions. 

It is worth to be noted that these definitions of first- and second-order distortions according to Warren-Averbach are model-free. From a linear or a quadratic increase of peak breadths it can neither be concluded in reverse that strain broadening, nor that paracrystalline disorder were detected. 

Model functions for the ID intensity have early been developed [128,158] and fitted to scattering data. The classical model-free structure visualization goes back to... 

For a general, isotropic and condensed multiphase material with short-range order, the CLD offers the best possible model-free visualization of the nanostructure. Nevertheless, the image does not show many details because of the inherent solid-angle average. 

Grant and coworkers [8] studied the dehydration kinetics of piroxicam monohydrate using both model-free and model-fitting approaches in an effort to understand the effects of lattice energy and crystal structure. The dehydration kinetics was found to differ when determined under isothermal and nonisothermal conditions. Ultimately, the dehydration behavior of piroxicam monohydrate was determined by details of the crystal structure, which was characterized by an absence of channels and a complicated hydrogen-bonding network, and ab initio calculations proved useful in understanding the structural ramifications of the dehydration process. 

Zhao ]H, Curtis D, Sham PC. Model-free analysis and permutation tests for allelic associations. Hum Hered 2000 50[2] 133—139. 

The kinetics of the CTMAB thermal decomposition has been studied by the non-parametric kinetics (NPK) method [6-8], The kinetic analysis has been performed separately for process I and process II in the appropriate a regions. The NPK method for the analysis of non-isothermal TG data is based on the usual assumption that the reaction rate can be expressed as a product of two independent functions,/ and h(T), where f(a) accounts for the kinetic model while the temperature-dependent function, h(T), is usually the Arrhenius equation h(T) = k = A exp(-Ea / RT). The reaction rates, da/dt, measured from several experiments at different heating rates, can be expressed as a three-dimensional surface determined by the temperature and the conversion degree. This is a model-free method since it yields the temperature dependence of the reaction rate without having to make any prior assumptions about the kinetic model. 

To indicate to the reader that the theory is based on the observable distribution of charge and its theoretical consequences. It is thus not only model-free but relates directly to the measurable properties of a system. 

The same result has been obtained by Lipari and Szabo in their model-free approach.158 The first term in the above equation accounts for the effect of local order on the isotropic rotation through the factor 1 — S2, and the second term is due to the slower fluctuations in the local ordered clusters. This model-free approach has become popular among workers in the area of lyotropics and biomembranes. 

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