Armed concept

With these arguments in mind, this paper is a first attempt for improving GGS by combining ASR and ARMS concepts. Firstly, every nonstandard FCD is approximated by a set of piecewise exponentials and X is determined according to ASR. Secondly, ARMS concepts are introduced in order to improve the approximations provided by ASR as well as to guarantee detailed balance to the sampling process. 

With the purpose of improving GGS, the proposed method is a hybridism between simple adaptive quadrature methods (e. g. ASR) and ARMS concepts. In order to allow flexibihty for working with non-log-concave FCDs, ARMS introduces a Metropohs-Hastings (MH) step into adaptive rejection method, originally directed to tackle log-concave functions. Let z and x be respectively the current and next values of the variable under smdy X in the simulation process, let/ be the current nonstandard FCD of X, and let g be a piecewise approximate function for/. 

Transfer of the Armed-Disarmed Concept to Thioglycoside Glycosylation... 

Thus, it seems that the concept of anomeric electronic activation-deactivation at the anomeric center taking precedence over armed-disarmed in the remainder of the pyranose ring might have reasonable validity, but, in many instances, the difference in reactivity of the p-nitrophenyl thioglycoside versus the p-acetamidophenyl thioglycoside is not enough to make this work (Scheme 1l).94... 

The armed-disarmed concept is tranferrable to having thioglycosides both as donors and acceptors91,92 (Scheme 9). Anomeric activation can, in favorable instances, also be used for this purpose93 (Scheme 10). 

Armed with the understanding that nucleophilicity and basicity are not the same concepts, we can now categorize reagents into the following four groups ... 

Global nuclear material management, started at Sandia National Laboratories as a visionary concept for tying the national security benefits of materials back to proliferation prevention, arms control and civilian nuclear power. Under the leadership of Senator... 

The same concept of using mutually interfering acid and base catalysts was achieved by Frechet s group through the use of star polymer systems [30]. The synthesis of the catalysts is outlined in Scheme 5.13. The arms of the star polymers prevent the catalysts from interfering with each other and allow the cascade reaction to proceed unhindered. 

According to present-day concepts, our solar system was formed from a huge gas-dust cloud several light years across in a side arm of the Milky Way. The particle density of this interstellar material was very low, perhaps 108-1010 particles or molecules per cubic metre, i.e., it formed a vacuum so extreme that it can still not be achieved in the laboratory. The material consisted mainly of hydrogen and helium with traces of other elements. The temperature of the system has been estimated as 15 K. 

In this chapter, we will introduce a bioinspired approach to biomineralization. First, a fundamental concept of the bioinspired approach is compared with the biomimetic approach. Here is a question, What is a bioinspired approach If we want to fly in the sky, when we look at flying birds what do we have to do Two kinds of typical answer were considered, as shown in Figure 6.4. One is Bird-Man, in the Edo period (AD 1600) in Japan, a man named Kokichi attempted to fly. He wore wide, large wings on both his arms, and fluttered his arms vigorously, but in vain. This is a typical biomimetic approach. He only mimicked the style of a flying bird, so his innovative idea ended in failure. 

Marple, VA. and Rubow, K.L. (1980). Aerosol generation concepts and parameters. In Generation of Aerosols and Facilities for Exposure Experiments (Willeke, K., Ed.). Arm Arbor Science, Arm Arbor, p. 6. 

Scheme 5.8 Armed/disarmed concept for chemoselective coupling of two w-pentenyl glycosides (NPGs). A 2-0-alkylated (armed) NPG 29 is much more readily activated than is a 2-0-acylated (disarmed) NPG 30.62...

The concept of armed/disarmed glycosyl donors was subsequently extended by other groups to thioglycosides21 and selenoglycosides.64 A similar strategy has been used by Friesen and Danishefsky to achieve chemoselectivity in electrophilic addition to glycal double bonds.65... 

A one-page essay in which it is suggested that evolution in plankton is driven by a watery arms race has attracted much attention (Smetacek 2001). Smetacek discusses the concept that defence of phytoplankton by mechanical protection, increased cell size, formation of spines, or production of noxious chemicals leads to the adaptation of zooplankton to these measures. This process resulted in the shape and properties of phyto- and zooplankton that we observe today. In the years following that essay several candidate molecules were discovered and intensely studied. The concept that chemical signals and defence metabolites are important factors in plankton ecology has now become widely accepted. 

Coevolution is defined as reciprocal stepwise adaptations between at least two species (Ehrlich and Raven, 1964). Coevolution without the criterion of reciprocity is indistinguishable from evolution and hence a useless concept (Lindroth, 1988). Consider the following scenario. A plant develops effective antiherbivore defenses. In response, a herbivore counteradapts to circumvent these defenses and is at a competitive advantage over other herbivores. The plant, in turn, responds to this breach of its defenses. In insects, such pairwise reciprocal evolution can take the form of a chemical arms race (Dawkins and Krebs, 1979). Coevolution differs from evolution by being narrower, with fewer participants, perhaps even only two species or two populations. In reality, in most ecosystems, many species prey on many other species. Therefore, we can at best speak of diffuse coevolution, with a number of participants that exert diluted selection pressures. 

In a series of important papers, MacMillan described the alkylation of electron rich aromatic and heteroaromatic nucleophiles with a,P-unsaturated aldehydes, using catalysts based upon the imidazoUdinone scaffold, further establishing the concept and utility of iminium ion activation. In line with the cycloaddition processes described above, the sense of asymmetric induction of these reactions can be rationalised through selective (F)-iminium ion formation between the catalyst and the a,P-unsaturated aldehyde substrate, with the benzyl arm of the catalyst blocking one diastereoface of the reactive Jt-system towards nucleophilic attack (Fig. 3). 

Naturally, the concept of intramolecular coordination in hthium chemistry via side-arm complexation is not limited to aromatic planar aryls. Like the metalation of cyclohexane... 

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