Confinement approaches

Krivov, S.V. Chekmarev, S.F. Karplus, M., Potential energy surfaces and conformational transitions in biomolecules A successive confinement approach applied to a solvated tetrapeptide, Phys. Rev. Lett. 2002, 88, 038101... 

In this work, we report on the fabrication of buried channel waveguide lasers in Nd YAG ceramics by using a two line confinement approach. Light confinement has been achieved between two... 

The confinement system provides for confining the fission products that might be released from a reactor during a nuclear incident. It is important to note that this is a confinement rather than containment system. The familiar total containment sphere is not utilized. The confinement approach is necessary because of the massiveness of the Hanford Production Reactors and the fact that containment vessels must be built before or with the reactor. 

Certainly a variety of confinement approaches and blanket designs can and should be considered for satellite approaches. SAFFIRE provides a first indication of the wide range of possibilities. 

Greenspan, "Confinement Approaches for Burning Alternate Fuels," Fourth Topical Meeting, Technology of Controlled Nuclear Fusion, King of Prussia, PA (1980), p. 270. Rikihisa, H. Nakashima, and M. Ohta, "Characteristics of Advanced-Fuel Cycle for Base-Satellite Fusion Reactor System," Proc. 2nd Int. Conf. on Emerging Concepts in Nuclear Energy, Lausanne, Switzerland (April 1980). 

In each of these approaches, imaging is confined to the top of a single polymeric film by adjusting optical absorption. The penetration depth of the silylation agent and the attendant swelling of the polymer film must also be controlled to avoid distortion of the silylated image. Resists of this type are capable of very high resolution (Fig. 37). 

The problem with all the mirror approaches is that none has achieved the degree of confinement quaUty that the closed systems have. Closed systems ate characterized by magnetic field lines that close on themselves so that charged particles following the field lines remain confined within the system. 

Restraining a gaseous plasma from expanding and compressing is also a form of plasma modification. Two reasons for plasma confinement are maintenance of the plasma and exclusion of contaminants. Plasmas may be confined by surrounding material, eg, the technique of wall confinement (23). A second approach to confinement involves the use of magnetic fields. The third class of confinement schemes depends on the inertial tendency of ions and associated electrons to restrain a plasma explosion for a brief but usehil length of time, ie, forces active over finite times are required to produce outward particle velocities. This inertial confinement is usually, but not necessarily, preceded by inward plasma motion and compression. 

Finally, an alchemical free energy simulation is needed to obtain the free energy difference between any one substate of system A and any one substate of system B, e.g., Ai- In practice, one chooses two substates that resemble each other as much as possible. In the alchemical simulation, it is necessary to restrain appropriate parts of the system to remain in the chosen substate. Thus, for the present hybrid Asp/Asn molecule, the Asp side chain should be confined to the Asp substate I and the Asn side chain confined to its substate I. Flat-bottomed dihedral restraints can achieve this very conveniently [38], in such a way that the most populated configurations (near the energy minimum) are hardly perturbed by the restraints. Note that if the substates AI and BI differ substantially, the transfomnation will be difficult to perform with a single-topology approach. 

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