Limpet Shells from the Aterian Level 8 of El Harhoura 2 Cave (Témara, Morocco): Preservation State of Crossed-Foliated Layers

International audienceThe exploitation of mollusks by the first anatomically modern humans is a central question for archaeologists. This paper focuses on level 8 (dated around * 100 ka BP) of El Har-houra 2 Cave, located along the coastline in the Rabat-Témara region (Morocco). The large quantity of Patella sp. shells found in this level highlights questions regarding their origin and preservation. This study presents an estimation of the preservation status of these shells. We focus here on the diagenetic evolution of both the microstructural patterns and organic components of crossed-foliated shell layers, in order to assess the viability of further investigations based on shell layer minor elements, isotopic or biochemical compositions. The results show that the shells seem to be well conserved, with microstructural patterns preserved down to sub-micrometric scales, and that some organic components are still present in situ. But faint taphonomic degradations affecting both mineral and organic components are nonetheless evidenced, such as the disappearance of organic envelopes surrounding crossed-foliated lamellae, combined with a partial recrystallization of the lamellae. Our results provide a solid case-study of the early stages of the diagenetic evolution of crossed-foliated shell layers. Moreover, they highlight the fact that extreme caution must be taken before using fossil shells for palaeoenvironmental or geochronological reconstructions. Without thorough investigation, the alteration patterns illustrated here would easily have gone unnoticed. However, these degradations are liable to bias any proxy based on the elemental, isotopic or biochemical composition of the shells. This study also provides significant data concerning human subsistence behavior: the presence of notches and the good preservation state of limpet shells (no dissolution/recrystallization, no bioerosion and no abrasion/fragmentation aspects) would attest that limpets were gathered alive with tools by Middle Palaeolithic (Aterian) populations in North Africa for consumption

Two-stage hepatectomy for colorectal liver metastases in elderly adults

Two-stage hepatectomy is a surgical strategy developed for cases of bilobar multinodular liver metastases. It is performed when all lesions cannot be removed in a single procedure due to a too small remnant liver volume. The main principle in this approach is a consecutive resection in two stages. It relies on the liver regeneration between the two interventions, allowing the second hepatectomy to be performed with a lower risk of complications. Subjects are patients with colorectal cancer liver metastases who undergo surgery at the surgical departments of Military Medical Academy of Plovdiv and Eurohospital of Plovdiv. For the period 2009-2013, 96 radical resections (58 metachronous and 38 synchronous). Of them, 58 are patients over 65 years of age. We performed 7 two-stage hepatectomies, 4 of these patients are aged over 65 years. Blood loss and blood transfusion were without significant differences between these two age groups. Complications rate in the postoperative period and the length of hospital stay were comparable, despite the higher level of comorbidity in the group aged over 65 years. Two-stage liver resections are a good opportunity for a small group of patients with bilobar metastases. The indications for this procedure can be successfully applied for elderly patients with appropriate perioperative management concerning the high co-morbidity in this group

Thermal stability of the 'cave' mineral ardealite Ca2(HPO4)(SO4).4H2O

Thermogravimetry combined with evolved gas mass spectrometry has been used to characterise the mineral ardealite and to ascertain the thermal stability of this ‘cave’ mineral. The mineral ardealite Ca2(HPO4)(SO4)•4H2O is formed through the reaction of calcite with bat guano. The mineral shows disorder and the composition varies depending on the origin of the mineral. Thermal analysis shows that the mineral starts to decompose over the temperature range 100 to 150°C with some loss of water. The critical temperature for water loss is around 215°C and above this temperature the mineral structure is altered. It is concluded that the mineral starts to decompose at 125°C, with all waters of hydration being lost after 226°C. Some loss of sulphate occurs over a broad temperature range centred upon 565°C. The final decomposition temperature is 823°C with loss of the sulphate and phosphate anions