Meta-tuning

The selection of a schema matcher is obviously not a parameter it does not fit with the definitions provided in Sect. 2. But this is likely meta-tuning since one first needs to choose a schema matcher before tuning its parameters and using it. Furthermore,... 

Using a maize HDAC system, aroyl-pyrrolyl-hydroxamides (APHA) had been shown to exhibit 7-78-fold class Ha selectivity when appropriately modified. Continued fine-tuning of the APHA inhibitors, such as meta-fluorine-substituted 20, enabled the generation of an even more selective HDAC inhibitor, with HD1-A IC50 of 0.22 (iM, 176-fold selectivity and which inhibited human HDAC4 but not HDAC1 [53]. 

For investigations of intramolecular charge-transfer interactions, donor- and acceptor-substituted cyclophanes are particularly well suited, since they allow for wide variation of substitutents. Interplanar-distance and orientation of aromatic planes can be tuned by choosing appropriate bridge lengths. Synjanti conformational preferences have an additional influence on charge-transfer interactions. Severals studies of this kind were undertaken by Staab et al. 17,34-36]. In usually good yields they synthesized methoxy-sutetituted [2.2]meta- and metaparacyclo-phanes with bromo-, cyano-, nitro-, or ester-substituents. In the case of methoxy-substituted substrates, often a few percent of quinoid by-products do form, e.g., 40, 41, and 44, which have been isolated in some cases. 

By changing the ratio of the meta- and para-linked building blocks, it should be straightforward to systematically tune the cavities of the corresponding crescent and helical oligomers. Such a strategy is seen in few natural or unnatural systems and is generally applicable to the creation of nanocavities of different sizes. 

Previously reported work demonstrated that substituents can be used to tune the energies of excited states responsible for the emission spectra of certain group VIII metal complexes (1) and to modify significantly the absorption spectra of complexes displaying metal-to-ligand charge transfer (MLCT) bands (2). In this presentation, we summarize some recent attempts to use ligand substituents in our studies of transition metal complex photochemical reaction mechanisms. The particular subjects of interest are the metal ammine complexes M(NH3)5L where M is Rh(III) or Ru(II) and L is a meta- or para-substituted pyridine. 

Meta-cognitive processes These were coded in crew communication when hypotheses were generated ( I shonld be able to tune in to an ILS frequency using the dial on the VOR unit to get a reference for the inbound course 003 ), when changes were observed ( 1 have switched to the backup system and have now received an artificial horizon ), when rules were deducted ( when I put down the nose [in manual backup law] then speed increases ), when explanations were constructed C What is nty problem I cannot put in the frequency, etc. ), and when the task was stiuctured C I first want to stabilize the aircraft before finishing the ECAM checklist ). 

The question of choice comes into play in many places in the practice of constructing computational models. Once a chemical problem has been identified, there are a number of choices made by the practitioner a model is chosen, a particular computer code is decided upon and the practitioner decides between the variables that can be fine-tuned within the model (e.g. basic sets, interatomic potentials or optimization algorithm). Austen rightly points out that there is a meta-level choice before we even begin the models-based approach, and that is whether computational modeling should be used at all given the nature of the chemical problem. 

Thus, there are numerous choices to be made when applying computational modelling once a chemical problem has been identified the choice of model, and thereafter the choice of computer code to employ the model, for there are many, and choice between the variables that can be fine-tuned within the model such as basis sets, interatomic potentials or optimisation algorithm. But there is also a meta-choice whether to rely on computational models at aU. This latter choice is the focus of this chapter. 

Sohn WY, Cho K-J, Lee SY, Kang SS, Park YD, Kang H (2012) Solvent-assisted conformational isomerization (SACI) of meta-substituted phenols tuning relative stability, isom-erizatirai barrier, and IVR rate. Chem Phys Lett 525-26 37... 

Calix[n]arenes, which are phenolic macrocycles (Figure 1.5), were popularized by Gutsche in 1978, although calixarenes date back to Baeyer s work on phenol-formaldehyde chemistry in the ISTOs. " Calix[n]arenes are composed of phenolic units. The phenolic units are linked by methylene bridges at their 2- and 6-positions [meta positions). Gutsche et al. discovered that even-numbered calix[n]arenes ( = 4, 6, 8) were selectively obtained by tuning the reaction conditions for the phenolic derivatives and formaldehyde. 

In this paper we first compare the performances of two standard PSO versions using the standard parameters suggested in the literature. Then, we automatically tune the parameter values of both algorithms using a meta-optimization environment, to allow the two versions to perform at their best. 

A comprehensive review of Meta-Optimization methods, and automatic parameter tuning in general, can be foimd in [20]. 

SEPaT (Simple Evolutionary Parameter Tuning) is an implementation of the Meta-Optimization paradigm, introduced in [21]. In this case the algorithm used as Tuner-MH is Differential Evolution (DE [22]). 

The cations 73 and 74 represent a class of silyl cations which are stabilized by intramolecular a -donation from the flanking aryl groups of the meta-terphenyl substituent. This offers the possibility to tune their reactivity by suitable choice of the substituent. Some evidence for this is provided by the high-field-shifted Si NMR resonance detected for cation 73d with the electron-rich pentamethylaryl substituent compared to that of the xylyl-substituted cation 73a (8 Si (73d) = 58.6 vs. S Si (73a) = 80.1). 

---