Dark Ages Cold Period: A literature review and directions for future research

Several late Quaternary studies have recorded cold and disturbed climates centred during the mid-first millennium AD and discussed these conditions under the term ‘Dark Ages Cold Period’ (DACP). A review of 114 palaeoclimate papers indicated that cold climates were common in the Northern Hemisphere between AD 400 and 765. There are also suggestions that some regions may have been relatively wet during the DACP, while those around the Mediterranean and the China/Tibetan Plateau indicate coinciding droughts. A set of environmental responses, however, indicate a delayed DACP interval (AD 509–865) postdating the actual climate signal. Previously, the DACP has been linked with the North Atlantic ice-rafting event at about 1400 years ago, while some evidence suggests an involvement of the North Atlantic Oscillation and/or El Niño–Southern Oscillation. More recently, another proposed phase of widespread cooling, the ‘Late Antique Little Ice Age’ (LALIA), overlaps with the DACP and has been tentatively linked with volcanic aerosol and solar irradiance variations reinforcing the climatic downturn since AD 536. Importantly, a higher number of proxy records extending over the first millennium AD is required for more rigorous assessments of climate variability and the forcing during these centuries and to disentangle the DACP and LALIA fingerprints in the proxy data, particularly to determine whether the DACP and the LALIA are distinct features. Also a richer network of both climate and environmental proxies is needed to evaluate the human–environment interactions, during the historical Migration Period, and thus through the DACP

Distal radius fractures in children: substantial difference in stability between buckle and greenstick fractures

Background and purpose Numerous follow-up visits for wrist fractures in children are performed without therapeutic consequences. We investigated the degree to which the follow-up visits reveal complications and lead to change in management. The stability of greenstick and buckle fractures of the distal radius was assessed by comparing the lateral angulation radiographically

Cowries in the archaeology of West Africa: the present picture

Despite the perceived importance of cowrie shells as indicators of long-distance connections in the West African past, their distribution and consumption patterns in archaeological contexts remain surprisingly underexplored, a gap that is only partly explicable by the sparse distribution of archaeological sites within the sub-continent. General writings on the timeline of importation of cowries into West Africa often fail to take into account the latest archaeological evidence and rely instead on accounts drawn from historical or ethnographic documents. This paper is based on a first-hand assessment of over 4500 shells from 78 sites across West Africa, examining chronology, shell species and processes of modification to assess what distribution patterns can tell us about the history of importation and usage of cowries. These first-hand analyses are paralleled by a consideration of published materials. We re-examine the default assumption that two distinct routes of entry existed — one overland from North Africa before the fifteenth century, another coming into use from the time sea links were established with the East African coast and becoming predominant by the middle of the nineteenth century. We focus on the eastern part of West Africa, where the importance of imported cowries to local communities in relatively recent periods is well known and from where we have a good archaeological sample. The conclusion is that on suitably large assemblages shell size can be an indication of provenance and that, while the present archaeological picture seems largely to confirm historical sources, much of this may be due to the discrepancy in archaeological data available from the Sahara/Sahel zone compared to the more forested regions of the sub-continent. Future archaeological work will clarify this matter

Calcar screws and adequate reduction reduced the risk of fixation failure in proximal humeral fractures treated with a locking plate: 190 patients followed for a mean of 3 years

Abstract Background Fixation of proximal humeral fractures (PHF) with locking plates has gained popularity over conservative treatment, but surgery may be complicated with infection, non-union, avascular necrosis (AVN) of the humeral head and fixation failure. Failure to achieve structural support of the medial column has been suggested to be an important risk factor for fixation failure. The aims of this study were to examine the effect of calcar screws and fracture reduction on the risk of fixation failure and to assess long-term shoulder pain and function. Methods This was a single-centre retrospective study of 190 adult PHF patients treated with a locking plate between 2011 and 2014. Reoperations due to fixation failure were the primary outcome. Risk factors for fixation failure were assessed using the Cox regression analysis. Postoperative shoulder pain and function were assessed by the Oxford Shoulder Score (OSS). Results Thirty-one of 190 (16%) patients underwent a reoperation: 14 (7%) due to fixation failure, 10 (5%) due to deep infection and 2 (1%) due to AVN. The absence of calcar screws and fixation with residual varus malalignment (head-shaft angle < 120°) both increased the risk of fixation failure with an adjusted hazard ratio (95% CI) of 8.6 (1.9–39.3; p = 0.005) and 4.9 (1.3–17.9; p = 0.02), respectively. The median (interquartile range) OSS was 40 (27–46). Conclusion The use of calcar screws, as well as the absence of postoperative varus malalignment, significantly reduced the risk of fixation failure. We, therefore, recommend the use of calcar screws and to avoid residual varus malalignment to improve the medial support of proximal humeral fractures treated with a locking plate