Search

The secondary $\ensuremath{\gamma}$ rays emitted following a nuclear reaction are often relatively straightforward to detect experimentally. Despite the large volume of such data, a practical formalism for describing these $\ensuremath{\gamma}$ rays in terms of partial-wave $T$-matrix elements has never been given. The partial-wave formalism is applicable when $R$-matrix methods are used to describe the reaction in question. This paper supplies the needed framework, and it is demonstrated by the application to the $^{15}\mathrm{N}(p,{\ensuremath{\alpha}}_{1}\ensuremath{\gamma})^{12}\mathrm{C}$ reaction.

Implant restorations for edentulous patients may be planned as either fixed restorations or removable overdentures. Several factors should be considered when deciding between these treatment alternatives. They may be grouped into factors related to (1) the entire patient, (2) both arches, (3) maxillary restorations, and (4) mandibular restorations.

The elements between iron and strontium are largely produced by the weak s-process occurring in massive stars during the late stages of convective core He burning and the convective shell carbon burning with the primary source of neutrons coming from the reaction 22Ne(α,n)25Mg. However, shell carbon burning may produce hot enough temperatures to activate 12C(12C,n)23Mg as a significant neutron source. Few studies have been done on this reaction, and the extrapolation from experimental data down to the relevant astrophysical energies is uncertain. Recent studies performed at the Nuclear Science Laboratory of Notre Dame aim to improve the existing reaction data using new experimental techniques as well as provide a more reliable extrapolation to the low energies not accessible by experiment. Preliminary results will be presented and the astrophysical implications will be discussed.

Implant abutments can be exposed to a variety of oral prophylaxis procedures. In this in vitro study, titanium abutments were subjected to five oral prophylaxis treatment modalities; a metal scaler, a plastic scaler, a rubber cup, a rubber cup with tin oxide, and an air-powder abrasive. The abutment surfaces were then examined under both light and scanning electron microscopes. The metal scaler was seen to roughen the titanium surface. All other modalities tested appeared to smooth the titanium surface by removing surface debris and rounding off the sharp machined grooves present on the untreated abutment surface.

The mesial rest may be an excellent method of reducing unfavorable occlusal forces acting on the abutment tooth. However, when anatomic conditions and therapeutic necessity require alternatives, the distal rest may be used. The use of the distal rest demands that additional procedures be used to reduce the occlusal trauma to the abutment tooth.

The modification of the altered cast tehnique as described permits the dentist to determine the correct extension of the denture base, control the relationship of tooth and tissue-bearing areas of the prosthesis, and make centric jaw relation records in a single clinical visit.