Plausible models

The pores in question can represent only a small fraction of the pore system since the amount of enhanced adsorption is invariably small. Plausible models are solids composed of packed spheres, or of plate-like particles. In the former model, pendulate rings of liquid remain around points of contact of the spheres after evaporation of the majority of the condensate if the spheres are small enough this liquid will lie wholly within the range of the surface forces of the solid. In wedge-shaped pores, which are associated with plate-like particles, the residual liquid held in the apex of the wedge will also be under the influence of surface forces. 

Impurities travel from atmosphere to ice sheet surface either attached to snowflakes or as independent aerosols. These two modes are called wet and dry deposition, respectively. The simplest plausible model for impurity deposition describes the net flux of impurity to ice sheet (which is directly calculated from ice cores as the product of impurity concentration in the ice, Ci, and accumulation rate, a) as the sum of dry and wet deposition fluxes which are both linear functions of atmospheric impurity concentration Ca (Legrand, 1987) ... 

Students in this group always worked simultaneously with the macro, sub-micro and symbolic levels. They did so trying to make the representation in one level be a support for the development of both a representation in another level and a plausible model that could explain the systems they observed. In Activity 3, when building... 

Electrochemical studies performed in the 7 x Cys-Aspl4 D. afri-canus Fdlll indicate that the reduced [3Fe-4S] center can react rapidly with Fe to form a [4Fe-4S] core that must include noncysteinyl coordination (101). The carboxylate side chain of Asp 14 was proposed as the most likely candidate, since this amino acid occupies the cysteine position in the typical sequence of a 8Fe protein as indicated before. The novel [4Fe-4S] cluster with mixed S and O coordination has a midpoint redox potential of 400 mV (88). This novel coordinated state with an oxygen coordination to the iron-sulfur core is a plausible model for a [4Fe-4S] core showing unusual spin states present in complex proteins (113, 114). 

Tamaki and Honza (1991) summarized the previously proposed models and the currently plausible models of back-arc spreading (Fig. 1.163). 

The above summarized mineralogical and geochemical studies on Kuroko and Mariana chimneys (Shikazono and Kusakabe, 1999), and previous studies on midoceanic ridge chimneys, combined with the studies of mineral particle behaviors in the plumbing system, are used to develop the following plausible model for the growth history of sulfate-sulfide chimneys on the seafloor (Shikazono and Kusakabe, 1999). 

Since the ion transfer is a rather fast process, the faradaic impedance Zj can be replaced by the Warburg impedance Zfy corresponding to the diffusion-controlled process. Provided that the Randles equivalent circuit represents the plausible model, the real Z and the imaginary Z" components of the complex impedance Z = Z —jZ " [/ = (—1) ] are given by [60]... 

Monod J, Wyman J, Changeux J-P. On the nature of allosteric transitions a plausible model. J Mol Biol 1965 12 88-118. 

Nucleic acids, DNA and RNA, are attractive biopolymers that can be used for biomedical applications [175,176], nanostructure fabrication [177,178], computing [179,180], and materials for electron-conduction [181,182]. Immobilization of DNA and RNA in well-defined nanostructures would be one of the most unique subjects in current nanotechnology. Unfortunately, a silica surface cannot usually adsorb duplex DNA in aqueous solution due to the electrostatic repulsion between the silica surface and polyanionic DNA. However, Fujiwara et al. recently found that duplex DNA in protonated phosphoric acid form can adsorb on mesoporous silicates, even in low-salt aqueous solution [183]. The DNA adsorption behavior depended much on the pore size of the mesoporous silica. Plausible models of DNA accommodation in mesopore silica channels are depicted in Figure 4.20. Inclusion of duplex DNA in mesoporous silicates with larger pores, around 3.8 nm diameter, would be accompanied by the formation of four water monolayers on the silica surface of the mesoporous inner channel (Figure 4.20A), where sufficient quantities of Si—OH groups remained after solvent extraction of the template (not by calcination). 

Fig. 4.20 Plausible models of DNA accommodation in mesopore silica channels (A) within a larger pore (B) within a smaller pore.

A deep stirred vessel is provided with two impellers on a single shaft. Feed is between the impellers. A plausible model for such a vessel is two CSTR s partly in parallel and partly in series, followed by a PER, as indicated on the sketch. Let a be the fraction of the total feed that goes to the first CSTR, and let 0 and j be the fractions of the volume occupied by each of the CSTRs. Find the transfer function of the whole vessel and the response to impulse input. 

The poor agreement between different attempts to calculate 7S from plausible models or from semi-empirical rules underlines the importance of the experimental determinations of 7S. The main methods used for this are examined in Chapter III. 

The idea of finding the best model was extended by Jones et al. (1994). A dynamic programming algorithm was used to select the most plausible model, and the same authors also presented an ambitious method to predict the three-dimensional structure of the a-helical membrane proteins (Taylor etal., 1994). Finally, HMMs were used to model the overall structure of the membrane topology by two groups of researchers (Sonn-hammer et al., 1998 Tusnady and Simon, 1998). 

Although different techniques are used, all of these methods, except for Hartmann et al., search for the most plausible model. Thus, the definition of a reasonable target function seems to be the key issue. 

In addition, the results of such reactions have suggested plausible models for the mechanism of abiotic generation of optical activity, including an autocatalytic feedback mechanism (261). The latter involves random development of chiral crystals from achiral starting material, and solid-state reaction leading to products in which one enantiomer is in excess and thus can bias subsequent further crystallization (262). 

Our simplest continuous microheterogeneous model assumes that the luminophore exists in a distribution of spectroscopically different environmental sites. For a tractable, yet plausible, model each site is assumed to be quenched by normal Stem-Volmer quenching kinetics. For luminescence decays each individual component is assumed to give a single exponential decay with the following impulse response ... 

A. Lesne, and J. M. Victor, Chromatin fiber functional organization Some plausible models. 

A plausible model for the Big Lake occurrence involves a genetic relationship between BLUC cumulates and VMS sulphides, similar to VMS occurrences of the Kidd-Munro assemblage summarized by Barrie etal. (2001). This would be the first such documented occurrence outside of the Abitibi subprovince, and illustrates the potential for similar occurrences above large ponded cumulates. 

There may be more than one plausible model structure that can be used to describe the data. In that case, any plausible model is analysed in a similar way. If the goodness-of-fit of more than one model is acceptable (see Section 13.2.8.5), a procedure for selecting the best model is required. 

Another approach is to develop a global model that contains plausible models as special cases, defined by alternative values of particular parameters. This converts model uncertainty into uncertainty about the model parameters. Again this can be done using either Bayesian or non-Bayesian approaches. This approach is favored by Morgan and Henrion (1990), who describe how it can be applied to uncertainty about dose-response functions (threshold versus nonthreshold, linear versus exponential). 

Meta-models a global model is developed that contains plausible models as special cases, converting model uncertainty into uncertainty about model parameters. Again, this can be done using either Bayesian and non-Bayesian approaches. 

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