91 research outputs found
Integrated chronological control on an archaeologically significant Pleistocene river terrace sequence: the Thames-Medway, eastern Essex, England
Late Middle Pleistocene Thames-Medway deposits in eastern Essex comprise both large expanses of Palaeolithic artefact-bearing river sands/gravels and deep channels infilled with thick sequences of fossiliferous fine-grained estuarine sediments that yield valuable palaeoenvironmental information. Until recently, chronological control on these deposits was limited to terrace stratigraphy and limited amino-acid racemisation (AAR) determinations. Recent developments in both this and optically stimulated luminescence (OSL) dating make them potentially powerful tools for improving the chronological control on such sequences. This paper reports new AAR analyses and initial OSL dating from the deposits in this region. These results will help with ongoing investigation of patterns of early human settlement.
Using AAR, the attribution by previous workers of the interglacial channel deposits to both MIS 11 (Tillingham Clay) and MIS 9 (Rochford and Shoeburyness Clays) is reinforced. Where there are direct stratigraphic relationships between AAR and OSL as with the Cudmore Grove and Rochford Clays and associated gravels, they agree well. Where OSL dating is the only technique available, it seems to replicate well, but must be treated with caution since there are relatively few aliquots. It is suggested on the basis of this initial OSL dating that the gravel deposits date from MIS 8 (Rochford and Cudmore Grove Gravels) and potentially also MIS 6 (Dammer Wick and Barling Gravels). However, the archaeological evidence from the Barling Gravel and the suggested correlations between this sequence and upstream Thames terraces conflict with this latter age estimate and suggest that it may need more investigation
Middle and Late Pleistocene environmental history of the Marsworth area, south-central England
To elucidate the Middle and Late Pleistocene environmental history of south-central England, we report the stratigraphy, sedimentology, palaeoecology and geochronology of some deposits near the foot of the Chiltern Hills scarp at Marsworth, Buckinghamshire. The Marsworth site is important because its sedimentary sequences contain a rich record of warm stages and cold stages, and it lies close to the Anglian glacial limit. Critical to its history are the origin and age of a brown pebbly silty clay (diamicton) previously interpreted as weathered till.
The deposits described infill a river channel incised into chalk bedrock. They comprise clayey, silty and gravelly sediments, many containing locally derived chalk and some with molluscan, ostracod and vertebrate remains. Most of the deposits are readily attributed to periglacial and fluvial processes, and some are dated by optically stimulated luminescence to Marine Isotope Stage (MIS) 6. Although our sedimentological data do not discriminate between a glacial or periglacial interpretation of the diamicton, amino-acid dating of three molluscan taxa from beneath it indicates that it is younger than MIS 9 and older than MIS 5e. This makes a glacial interpretation unlikely, and we interpret the diamicton as a periglacial slope deposit.
The Pleistocene history reconstructed for Marsworth identifies four key elements: (1) Anglian glaciation during MIS 12 closely approached Marsworth, introducing far-travelled pebbles such as Rhaxella chert and possibly some fine sand minerals into the area. (2) Interglacial environments inferred from fluvial sediments during MIS 7 varied from fully interglacial conditions during sub-stages 7e and 7c, cool temperate conditions during sub-stage 7b or 7a, temperate conditions similar to those today in central England towards the end of the interglacial, and cool temperate conditions during sub-stage 7a. (3) Periglacial activity during MIS 6 involved thermal contraction cracking, permafrost development, fracturing of chalk bedrock, fluvial activity, slopewash, mass movement and deposition of loess and coversand. (4) Fully interglacial conditions during sub-stage 5e led to renewed fluvial activity, soil formation and acidic weathering
Preoperative progressive explosive-type resistance training is feasible and effective in patients with hip osteoarthritis scheduled for total hip arthroplasty – a randomized controlled trial
SummaryObjectiveTo investigate the efficacy and feasibility of progressive explosive-type resistance training (RT) in patients with osteoarthritis (OA) of the hip scheduled for total hip arthroplasty (THA).MethodRandomized controlled trial (1:1) in patients diagnosed with hip OA and scheduled for THA. The intervention group (IG) performed supervised preoperative progressive explosive-type RT twice a week for 10 weeks; four exercises (hip/thigh) performed in three series each (8–12 repetition maximum). The control group (CG) received ‘care as usual’.Efficacy was reported as the between-group difference in the Hip Osteoarthritis Outcome Score (HOOS) (primary endpoint; ADL function), and leg muscle power at post intervention follow-up immediate before surgery. Intention-to-treat analyses were performed in a multilevel regression model adjusting for baseline, sex, age and weight. Feasibility was reported as adherence, exercise related pain and adverse effects. Post-surgical follow up will be reported separately. ClinicalTrials.gov registration: NCT01164111.ResultsEighty patients (age 70.4 ± 7.6 years, BMI 27.8 ± 4.6, 52 females (65%) were included. Adherence was high (93%) with acceptable exercise related pain (VAS score ≤ 5) reported in 83% of sessions and no adverse events. Changes in HOOS ‘function’ was 10.0 points 95%CI [4.7; 15.3] higher in IG compared to CG (P < 0.001). For all the remaining HOOS subscales IG scored significantly better (P < 0.03) and had higher leg extension muscle power (P < 0.0001) compared to CG.ConclusionProgressive explosive-type RT was feasible in the included group of hip OA patients scheduled for THA and resulted in significant improvement in self-reported outcomes and increased leg muscle power
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