No abstract

Nuclear level structure of low lying levels of 1~ from 1~ decay has been investigated by gamma-gamma angular correlation experiments using a Ge(Li)-NaI(T1) fast coincidence arrangement. From the measurement on the 347. 4-326.3, 347.4-650.1, 287.7-650.1, 203.3-420.5, 203.3-619.3keV cascades spin-parity assignments of ~+, 1+ ~+, , 5+~-, and have been made to the ground, 59.5, 203.3, 347.4, 623.8, 673.7, 822.5 and 997.5 keV states, respectively, of i~ The results have been discussed and compared with the previous works.

The distribution of ionic charges has been measured for 12 C recoils from the elastic scattering of 10-MeV deuterons in carbon targets down to a thickness of 0.3 Mg/cm 2 . The charge distribution from the thinner targets is distinctly nonequilibrium, indicating that "instantaneous" effects of the atomic and nuclear processes which produced the recoils are being observed, unmodified by electron-exchanging interactions with matter.

Equilibrium and pre-equilibrium charge-state distributions have been measured for~~B recoils at a velocity of 11. 1x 10s cmf sec from~~B(d,d) elastic scattering in natural boron targets. A coupled set of linear differential equations describing the capture and loss of electrons has been derived for ions recoiling from nuclear processes in solids. It has been used to obtain electron-capture and -loss cross sections from the B recoil data. The results are consistent with the existence of very little two-electron capture or loss and, when compared with previous results in gaseous media, do not show any pronounced effects of residual-ion excitation.

Design and manufacture of orthopedic devices using rapid prototyping technologies has been until recently a highly iterative process that involves multiple users, including doctors, design engineers and rapid prototyping experts. Existing systems for creation of orthopedic parts through rapid prototyping do not follow the principles of concurrent engineering and design for manufacture. This leads to excessive conununication between parties and delays in product realization time.In this paper, we lay out the framework for a unified expert system that will enable a doctor to create quickly and easily fully functional prosthetics and orthopedic implants. Necessary components of the model acquisition pmcess should include volumetric segmentation of objects from a CT or MRI dataset and NURBS surface fitting to the boundary points. Finite element analysis and surface model modification modules are also needed, but should be provided in an intuitive fashion for doctors who are not experienced in computer aided design. Pre-processing for rapid prototype building should be automatic, and should include optimal orientation, support structure generation and build simulation modules. Finally, the model should be passed to the rapid prototyping machine in a pre-sliced format for speed and accuracy.The method of design and manufacture of orthopedic devices has traditionally required isolated "islands" of people who have no common background. It has required that doctors sketch out the needed device while design and manufacturing engineers engage themselves in detailed design, process planning and manufacturing of the product. This means that the process of design optimization is highly iterative, going from doctor to design/manufacturing engineer and back again repeatedly. It also means that the doctor has no conirol over the product which he originally conceives, and issues of comfort for the patient and tolerances of the device can easily be disregarded in order to arrive at an "acceptable" design with a minimum number of design-to-manufacture iterations (Figure 1). A system that is fully concurrent with respect to design, analysis and manufacturing will give doctors the ability to easily produce (perhaps with the aid of a technician) fully functional, custom made orthopedic devices in a hospital in a very short amount of time.The solution currently being applied to this problem is to create prosthetic devices and surgical models in a variety of standard shapes and sizes. However, this seems to be an inadequate solution, since unlike machines, parts on human beings are not interchangeable. That is, no two people have identical body parts, which is evident when one considers the fact that the human body is composed solely of multi-curved surfaces. Existing orthopedics design systems do not take into account the process planning and manufacturing aspects of orthopedic/prosthetic device design.Recently, a number of technologies have evolved which will unify the processes of conceptual design, detailed design, process planning a...