Intensity simulated

Recently, molecular dynamics and Monte Carlo calculations with quantum mechanical energy computation methods have begun to appear in the literature. These are probably some of the most computationally intensive simulations being done in the world at this time. 

The tests in the two previous paragraphs are often used because they are easy to perform. They are, however, limited due to their neglect of intermolecular interactions. Testing the effect of intennolecular interactions requires much more intensive simulations. These would be simulations of the bulk materials, which include many polymer strands and often periodic boundary conditions. Such a bulk system can then be simulated with molecular dynamics, Monte Carlo, or simulated annealing methods to examine the tendency to form crystalline phases. 

We are thus led to assume that V and the fiuctuation-dissipation process driving the virtual body depends on the variable 17 so as to simulate the efiects of the H-bond dynamics. For example, a strong interaction potential V accompanied by friction and stochastic torques (forces) of weak intensity simulates the solidlike properties of the environment when the tt ed molecule is characterized by four hydrogen bonds. In this case a reasonable approximation is to simulate such an environment by ice Ih. In the opposite limit, a weak potential V with strong friction and stochastic torques (forces) simulates the difiusional properties of the unbounded molecule (liquid water at high temperature or in very dilute nonpolar solution). 

The application of proton-driven CSA correlation spectroscopy to amino-acid specifically carboxylic-labeled spider silk [63] is shown in Fig. 4.11. Spider silk is known to consist of alanine- and glycine-rich domains [64, 65] and is known to be semicrystalline. The assignment of alanine to the (crystalline) /3-sheet domains [66] is clearly supported by the chemical-shift correlation spectrum of Fig. 4.11. Because the tensors in a j8-sheet structure are almost parallel, or antiparallel, with the tensors in spatial proximity, a diagonal spin-diffusion spectrum is expected for that structure and is indeed found. In contrast, the glycine spectrum shows considerable off-diagonal intensity. Simulations have shown that the spectrum is compatible with a local 3i-helical structure [63]. 

While our attention in this chapter has thus far been focused mainly on simple methods for calculating the surface tension and the interfacial tension, it is important to point out the new techniques of a more physically fundamental nature that are being developed rapidly to predict interfacial behavior. Most of these techniques are based on numerically intensive simulations. Some of them were mentioned briefly in Section 7.C. 

After the revolutionary development of computing hardware, computer science, and computer intensive simulation in the second half of the 20th century, the hallmark of the new century/millennium is the flood of electronically accessible data. Thanks to the unexpected development of measurement techniques, data pervades and transforms traditionally data-poor, knowledge-rich sciences such as biology and medicine. However, compared to astrophysics or business, the status and role of data in biomedicine is unique in many respects, such as the presence of multiple, weakly connected levels and the possibility of completeness of an observation of a given level, that is, the -omics. 

Indeed, numerically intensive simulations have often proved impractical before the appropriate analytical work illustrated what to expect. 

Computer simulations have become an important research tool for determining the properties of polymers. With the advent of fast workstations, many computationally intensive simulations can now be carried out on reasonable time scales. Furthermore, recent studies have demonstrated the power of simulations to predict polymer properties, especially at interfaces and in solution. Thus, simulation can provide a valuable tool to supplement the ongoing NRL research on the interface between phase-separated domains and would complement current NRL studies in the area of blends and composites. There also exists at NRL considerable expertise in molecular dynamics techniques and other simulation methods. Consequently, a collaboration between the two groups in this area would provide a rich research opportunity. 

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