Bottom-down approach

How do you then design an effective system There are several techniques you can use. Failure Modes and Effect Analysis (FMEA), Fault Tree Analysis (FTA), and Theory of Constraints (TOC) are but three. The FMEA is a bottom-up approach, the FTA a top-down approach, and TOC a holistic approach. 

The FMEA approach is a bottom-up approach, looking at component failures and establishing their effect on the system. An alternative approach is to use a top-down approach such as Fault Tree Analysis to postulate system failure modes and establish which processes, procedures, or activities are likely to cause such failures. 

Collectivism is thus distinct from both the top-down reductionist approach traditionally favored by most physicists (system as a simple edifice of its microscopic parts), and the more recent neural-net-like bottom-up approach favored by connec-tionists (system as a synthesis of its constituent parts). The nonlinear inter-level feedback loop that makes up the collective is what makes a traditional linear analysis of such systems difficult, if not impossible. 

Nanomaterials can be manufactured by one of two groups of methods, one physical and one chemical. In top-down approaches, nanoscale materials are carved into shape by the use of physical nanotechnology methods such as lithography (Fig. 15.30). In bottom-up approaches, molecules are encouraged to assemble themselves into desired patterns chemically by making use of specific... 

Distinguish between the top down and bottom up approaches to manufacturing nanomaterials. 

The top down approach refers to physically assembling the nanoparticles into desired forms the bottom up approach utilizes specific intermolecular interactions to cause the nanomaterials to self-assemble. 

Biotic indices that are relatively simple and inexpensive to apply can be very useful for identifying environmental problems caused by pollutants. Serious effects of pollutants can cause departures from normal profiles. The problem is, however, identifying which pollutants—or which other enviromnental factors—are responsible for significant departures from normality. This dilemma illustrates well the importance of having both a top-down and a bottom-up approach to pollution problems in the field. Chemical analysis and biomarker assays can be used to identify chemicals responsible for adverse changes in communities detected by the use of biotic indices. 

Different synthetic methodologies can be pursued to prepare hierarchical porous zeolites, which can be discriminated as bottom-up and top-down approaches. Whereas bottom-up approaches frequently make use of additional templates, top-down routes employ preformed zeolites that are modified by preferential extraction of one constituent via a postsynthesis treatment For the sake of conciseness, we restrict ourselves here to the discussion of the latter route. Regarding bottom-up approaches, recently published reviews provide state-of-the-art information on these methodologies [8, 9,17-19]. 

Nanotechnology is the branch of engineering that deals with the manipulation of individual atoms, molecules, and systems smaller than 100 nanometers. Two different methods are envisioned for nanotechnology to buUd nanostructured systems, components, and materials. One method is the top-down approach and the other method is called the bottom-up approach. In the top-down approach the idea is to miniaturize the macroscopic structures, components, and systems toward a nanoscale of the same. In the bottom-up approach the atoms and molecules constituting the building blocks are the starting point to build the desired nanostmcture [96-98]. 

Various illustrations are available in the literature depicting the comparison of top-down and bottom-up approaches [96, 97]. In the top-down method a... 

Let s assume that the inputs to the supremal decision unit are a subset of all the decision variables attached to infimal decision units, consisting of those variables that are believed to be particularly influential with respect to the operation of the overall system. Then, an application of basic to DUj, results directly in the identification of a decision policy, X p. This decision policy is then passed down to the lower level in the hierarchy, where it is submitted to a process of validation and refinement by all infimal decision units that is identical to the one that takes place in the bottom-up approach. 

FIGURE 9.1 Liquid chromatography workflow strategy options in proteomics. (a) bottom-up approach (b) top-down approach (c) selective sample cleanup directly combined with chromatographic separation (d) peptide capture with affinity restricted access material. 

The combination of this top-down proteomics approach, which generates information on the structure of the intact protein, with a bottom-up approach for protein identification (using MS/MS data of tryptic peptides from the collected fractions) has been particularly useful for identifying posttranslational modifications, cotransla-tional processing, and proteolytic modifications in a number of proteins. Examples from our work will be shown to illustrate this hybrid methodology for proteomics analysis. 

In recent years, a novel approach to protein identification emerged, called top-down sequencing. Here the entire nondigested protein is analyzed. Apart from accurate MW measurement, the protein ion is fragmented by the electron capture dissociation (ECD) method (see Chapter 3). This provides in-depth information on the sequence of protein. Such analysis can be performed only with FTICR instruments (see Section 2.2.6) that ensure high resolution and accuracy but, at the same time, they are exceptionally expensive. However, as very large ions are analyzed, even the high accuracy of FTICR is sometimes not sufficient, and it is recommended that such analyses are accompanied by more traditional bottom-up approaches. 

Bottom-up and Top-down Approaches. Our approach to refinement between spec and design (and other layers of documentation) in no way constrains you to begin with the requirements and end with the code. Called upon to write an article, you need not begin at the beginning. Instead, you edit the whole in any order you like as long as it makes sense when you ve finished. Similarly, the context of a project may call for a different route through the method (see Section 13.2.1, Multiple Routes through the Method). 

Abstract This article is a review of the chemical and physical nature of patternable block copolymers and their use as templates for functional nanostructures. The patternability of block copolymers, that is, the ability to make complex, arbitrarily shaped submicron structures in block copolymer films, results from both their ability to self-assemble into microdomains, the bottom-up approach, and the manipulation of these patterns by a variety of physical and chemical means including top-down lithographic techniques. Procedures for achieving long-range control of microdomain pattern orientation as well... 

The use of top-down lithographic techniques to topographically pattern substrates and thereby control the film thickness has been used to create submicron patterns that contain oriented microdomains. This approach is generally described as the graphoepitaxy method and will be discussed in further detail in Sect. 4.1, with other methods which use top-down approaches to control the bottom-up block copolymer patterns. 

Combination of Top-Down and Bottom-Up Approaches to Give Multilevel Control of Block Copolymer Patterns... 

---