Checkerboard analysis

Checkerboard analysis. The filter assay does not allow one to directly observe migration of cells, and track them to establish... 

Fig. 3.1. A scheme illustrating checkerboard analysis of directed cell motility. Three fields are identified in the scheme (1) wells in field I contain an equal amount of chemoattractant in the upper and lower compartments (2) wells in field II contain a higher concentration of chemoattractant in the lower than in the upper compartments and (3) the reverse happens for wells in field III.

Figure 8 Schematic of checkerboard analysis control DNA digest TLC.

Figure 9 Schematic of checkerboard analysis reveals adduct.

Retrospective approaches can be applied. In such cases, the analyzed region (that nsed to constmct the depth profile) is defined following data collection. There exist two methodologies that can be used. These are otherwise referred to as Region of Interest (ROI) analysis or Checkerboard analysis. 

Checkerboard analysis describes a methodology in which the sputtered region is divided into a checkerboard-like surface (16 X 16 to 128 X 128 are common) with the depth profile then constructed from the secondary ion signal from one or a combination of the freely selectable squares. This filtering capability can be found on some Qnadmpole-based and Magnetic Sector-based SIMS instmments. 

For both ROI analysis and checkerboard analysis, the spatial distribntion of the secondary ions emanating from the sputtered surface must be imaged spatially such that the region from which the depth profile is to be reconstrncted can be visnalized. 

The surface has often been considered to be a checkerboard of fixed sites on which reactions take place. However, in recent years our ideas of the surface have changed partly due to LEED analysis, but perhaps more significantly due to the advent of the atomically resolving techniques of field ion microscopy (F1M), high resolution electron microscopy (HRTEM) and especially scanning tunnelling microscopy (STM). 

Battifora H, Mehta P. The checkerboard tissue block An improved multitissue control block. Lab Invest. 1990 63 722. Skacel M, Skilton B, Peltay JD, et al. Tissue microarrays A powerful tool for high-throughput analysis of clinical specimens A review of the method with validation data. Appl Immunohistochem Mol Morphol. 2002 10 1. 

In this book, we have tried to capture not only the state of the art pertaining to cyclone technology but to also capture and convey as much of our 55 cumulative years of experience as possible and, in some few cases, permissible. Still, there are areas where further research and analysis is required to fill the gaps in the checkerboard of our understanding. We hope this book will be a stepping-stone and an aid to all those who work with cyclones and who find them as useful and fascinating as we do. 

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