The influence of different tempers on the composition of pottery
The modification of the raw clay by the potter to produce a paste suitable for the intended purposes adds a layer of obfuscation to the problem of provenancing the original clay source by chemical fingerprinting. By preparing different pastes from the same commercially available raw clay and their chemical analysis by Instrumental Neutron Activation Analysis, an experiment under controlled conditions (tempers, mixing ratios, firing temperatures and sampling methods) sheds light on the influence of different tempers. The results show that two different sampling procedures (drilling and grinding) have almost no influence on the chemical fingerprint with the exception of the elemental concentrations of As, Zr, and Hf. This may be due to the volatility of the compounds (As) or the presence of zircon crystals (containing Zr and Hf) which are partly lost during drilling. Three different firing temperatures show no significant influence as well. The application of the modified Mahalanobis distance introduced by Beier and Mommsen in 1995 as a statistical filter and the introduction of a ‘dilution factor’ to the raw data show that the influence of quartz-dominated tempers can be filtered out of the data, resolving the underlying chemical fingerprint of the original clay source. At the same time, by mathematically removing the additional spread introduced by dilution, even subtle differences between similar pastes can be resolved by standard multivariate statistical means.
Thin Section Microscopy Applied to the Study of Archaeological Ceramics
For the characterization of archaeological ceramics, the study of thin sections under the polarizing microscope is a very efficient analytical technique. There are two properties of ceramics which can be analysed by thin sections, namely the mineralogical composition and the fabric. Both features show a considerable variety which permits a very detailed description of ceramic wares. With respect to the mineralogical composition, there is a wide variety of rock forming minerals, of heavy and ore minerals, fragments of stone, fossils, organic inclusions like straw or pieces of charcoal as well as artificial inclusions like slag or crushed pottery, which define with the temper of the pottery in much detail. The fabric also shows considerable differences in grain size, in the amount of temper, in the orientation of grains and other features, which provide further quantitative data on the properties of archaeological ceramics. From this information, the material can be well characterised, and conclusions as to the region of origin and the potter's techniques can often be drawn.
Botulinum toxin in the management of chronic migraine: clinical evidence and experience
Chronic migraine (CM) is a severely disabling neurological condition characterized by episodes of pulsating unilateral or bilateral headache. The United States Food and Drug Administration (FDA) approved onabotulinumtoxinA (Botox®) for the prophylactic treatment of CM in 2010. It has been shown that onabotulinumtoxinA is effective in the reduction of headache frequency and severity in patients with CM. Treatment is well tolerated by the patients. This review reports on the history of botulinum neurotoxin (BoNT) in CM and presents the current clinical evidence for the use of onabotulinumtoxinA in the treatment of CM.