In this paper we will prove analogues of B. Maier’s characterization of weak and strong embeddability of amalgams in N2 [12, 13] for the subvarieties of N2. We will also give analogues of D. Saracino’s characterization of weak and strong amalgamation bases [17], the author’s work on dominions [11] and on amalgamation bases in some varieties of nil-2 groups [8, 9]. Definitions will be recalled b...

introduction: dentists are exposed to mercury vapor from dental amalgam in their routine occupational practice; excess exposure to mercury is harmful. the aim of this study was to assess the influence of some possible related factors on the urine mercury levels of general dentists and restorative specialists in mashhad in 2010. materials and methods: this cross-sectional study was performed ran...

Using the characterization of dominions in the variety of nilpotent groups of class at most two, we prove that the infinite cyclic group is absolutely closed in this variety. We also conclude from the proof that the same is true of arbitrary cyclic groups. The main result of this paper is that cyclic groups are absolutely closed in the variety N2 (definitions are recalled in Section 1 below). W...

We introduce a new matroid width parameter based on the operation of matroid amalgamation, which we call amalgam-width. The parameter is linearly related to branch-width on finitely representable matroids, while still allowing the algorithmic application on non-representable matroids (which is not possible for branch-width). In particular, any property expressible in the monadic second order lo...

Seven multiple sclerosis subjects had their silver dental fillings (amalgams) removed which contained approximately 50% mercury. A visual evoked response (VER) test was performed before amalgam removal. Approximately six months after amalgam removal a second VER test was performed on all subjects, and the latencies of the VER decreased significantly. The mean latency of P1 for the right and lef...

The objective of the present study was to evaluate the efficiency of dental amalgam as retrograde filling material compared to gutta-percha. A prospective and comparative observational study was carried out on 30 patients at Khyber College of Dentistry, Peshawar from October 2004 to October 2009 with or without retrograde amalgam filling and the success was determined at the end of the year bot...

Dental amalgam has served as an excellent and versatile restorative material for many years. There is still no adequate economic alternative for dental amalgam. Pins are used whenever adequate resistance and retention forms cannot be established with slots.locks and other undercuts only. It is an important adjunt in the restoration of extensive carious teeth. Pins not only helps in binding of a...