Roman surface

Mobius strip. In this way the antimatter mystery disappears matter and antimatter are one and the same thing, which merely appear to be different depending on their position in the double cover. In more dimensions the Mobius model is replaced by a projective plane, obtained from an open hemisphere on identifying points on opposite sides of the circular edge. Topologically equivalent constructs are known as a Roman surface or a Klein bottle. 

In Roman times tar and pitch from Pinaceae resinous wood were used to treat the inner surface of amphorae to store fluids such as wine [ 145,149] and to seal ship planks [89,144], Heating treatments applied to natural resins and resinous wood profoundly modify the chemical composition of the original material. Diterpenoid compounds undergo aromati-zation, demethylation and decarboxylation reactions, with the formation of new compounds of a lower molecular weight that show a high degree of aromatisation [87,88]. In tar and pitch produced from Pinaceae resin and woods, retene is considered as a stable end product of these reaction pathways and nor-abietatrienes, simonellite and tetrahydroretene represent the intermediates of these reactions [87,89,150]. 

Baillie, P.J. and Stern, W.B. (1984). Non-destructive surface analysis of Roman terra sigillata a possible tool in provenance studies Archaeometry 26 62-68. 

If we accept a date of around AD 1000 for the commencement of the distillation of zinc on a large scale, then, following the work of Craddock (1978), all earlier brasses should contain less than 28% Zn, as this is the approximate upper limit for the calamine process at around 1000 °C. Above this temperature, the process is more efficient, but it is said that the brass produced melts and the active surface area for the process is thus reduced. By granulating the copper and therefore increasing the surface area, the maximum can be pushed to around 33% Zn, but it is unlikely that this was done in Europe until the 18th Century (see Section 6.4). This model is supported by the analytical data Craddock s work on Roman brass indeed shows an upper limit of about 28% zinc. 

Pouradier, J., et J. Roman Etude de quelques facteurs influengant l adsorption de la gelatine a la surface des cristaux d halog6nure d argent. Sci. industr. Photogr. (2) 23, 4 (1952). 

In order to identify the periodic orbits (POs) of the problem, we need to extract the periodic points (or fixed points) from the Poincare map. Adopting the energy F = 0.65 eV, Fig. 31 displays the periodic points associated with some representative POs of the mapped two-state system. The properties of the orbits are collected in Table VI. The orbits are labeled by a Roman numeral that indicates how often trajectory intersects the surfaces of section during a cycle of the periodic orbit. For example, the two orbits that intersect only a single time are labeled la and lb and are referred to as orbits of period 1. The corresponding periodic points are located on the p = 0 axis at x = 3.330 and x = —2.725, respectively. Generally speaking, most of the short POs are stable and located in... 

Figure 31. Periodic points of the Poincare map at the energy E = 0.65 eV. The Roman numerals indicate how often the corresponding orbit intersects the surface of section. Panel (b) shows an enlargement of the main regular island around x,p) = (3.3,0). The thin hnes represent various tori of the system.

The electrochemical replacement of one metal by another was noticed by Pliny in antiquity. He mentioned that iron looks like copper if it is smeared with vinegar or alum previously ground in a bronze mortar [275], Metal replacement seems to have also been used in the Roman era for tin-plating bronze, as well as underlying the recipes for the preparation of iron surfaces to receive amalgam gilding that are given in the 9th century [276],... 

Fig. 9.6. Section of human sclera, lO im thick, unstained and unfixed, (a) Cut parallel to the surface (left) acoustic (right) optical, (b) Cut perpendicular to the surface (left) acoustic (right) optical 450 MHz (courtesy of Roman Maev).

---