Extending the aridity record of the Southwest Kalahari: current problems and future perspectives

An extensive luminescence-based chronological framework has allowed the reconstruction of expansions and contractions of the Kalahari Desert over the last 50 ka. However, this chronology is largely based on near-surface pits and sediment exposures. These are the points on the landscape most prone to reactivation and resetting of the luminescence dating ‘clock’. This is proving to be a limiting feature for extending palaeoenvironmental reconstructions further back in time. One way to obviate this is to sample desert marginal areas that only become active during significant arid phases. An alternative is to find and sample deep stratigraphic exposures. The Mamatwan manganese mine at Hotazel in the SW Kalahari meets both these criteria. Luminescence dating of this site shows the upper sedimentary unit to span at least the last 60 ka with tentative age estimates from underlying cemented aeolian units dating back to the last interglacial and beyond. Results from Mamatwan are comparable to new and previously published data from linear dunes in the SW Kalahari but extend back much further. Analysis of the entire data set of luminescence ages for the SW Kalahari brings out important inferences that suggest that different aeolian forms (1) have been active over different time scales in the past, (2) have different sensitivities to environmental changes and (3) have different time scales over which they record and preserve the palaeoenvironmental record. This implies that future optically stimulated luminescence work and palaeoenvironmental reconstructions must consider both site location and its relationship to desert margins and sediment depositional styles, so that the resolution and duration of the aridity record can be optimally understood

Late Quaternary sea-level changes of the Persian Gulf

Late Quaternary reflooding of the Persian Gulf climaxed with the mid-Holocene highstand previously variously dated between 6 and 3.4 ka. Examination of the stratigraphic and paleoenvironmental context of a mid- Holocenewhale beaching allows us to accurately constrain the timing of the transgressive, highstand and regressive phases of the mid- to late Holocene sea-level highstand in the Persian Gulf. Mid-Holocene transgression of the Gulf surpassed today's sea level by 7100–6890 cal yr BP, attaining a highstand of N1 m above current sea level shortly after 5290–4570 cal yr BP before falling back to current levels by 1440–1170 cal yr BP. The cetacean beached into an intertidal hardground pond during the transgressive phase (5300–4960 cal yr BP) with continued transgression interring the skeleton in shallow-subtidal sediments. Subsequent relative sea-level fall produced a forced regression with consequent progradation of the coastal system. These new ages refine previously reported timings for the mid- to late Holocene sea-level highstand published for other regions. By so doing, they allow us to constrain the timing of this correlatable global eustatic event more accurately

Comparative safety of anesthetic type for hip fracture surgery in adults: retrospective cohort study

Objective: To evaluate the effect of anesthesia type on the risk of in-hospital mortality among adults undergoing hip fracture surgery in the United States. Design: Retrospective cohort study. Setting: Premier research database, United States. Participants: 73 284 adults undergoing hip fracture surgery on hospital day 2 or greater between 2007 and 2011. Of those, 61 554 (84.0%) received general anesthesia, 6939 (9.5%) regional anesthesia, and 4791 (6.5%) combined general and regional anesthesia. Main outcome measure In-hospital all cause mortality. Results: In-hospital deaths occurred in 1362 (2.2%) patients receiving general anesthesia, 144 (2.1%) receiving regional anesthesia, and 115 (2.4%) receiving combined anesthesia. In the multivariable adjusted analysis, when compared with general anesthesia the mortality risk did not differ significantly between regional anesthesia (risk ratio 0.93, 95% confidence interval 0.78 to 1.11) or combined anesthesia (1.00, 0.82 to 1.22). A mixed effects analysis accounting for differences between hospitals produced similar results: compared with general anesthesia the risk from regional anesthesia was 0.91 (0.75 to 1.10) and from combined anesthesia was 0.98 (0.79 to 1.21). Findings were also consistent in subgroup analyses. Conclusions: In this large nationwide sample of hospital admissions, mortality risk did not differ significantly by anesthesia type among patients undergoing hip fracture surgery. Our results suggest that if the previously posited beneficial effect of regional anesthesia on short term mortality exists, it is likely to be more modest than previously reported

Syngenetic sand veins and anti-syngenetic sand wedges, Tuktoyaktuk Coastlands, western Arctic Canada

Sand-sheet deposits of full-glacial age in the Tuktoyaktuk Coastlands, western Arctic Canada, contain syngenetic sand veins 1-21 cm wide and sometimes exceeding 9 m in height. Their tall and narrow, chimney-like morphology differs from that of known syngenetic ice wedges and indicates an unusually close balance between the rate of sand-sheet aggradation and the frequency of thermal-contraction cracking. The sand sheets also contain rejuvenated (syngenetic) sand wedges that have grown upward from an erosion surface. By contrast, sand sheets of postglacial age contain few or sometimes no intraformational sand veins and wedges, suggesting that the climatic conditions were unfavourable for thermal-contraction cracking. Beneath a postglacial sand sheet near Johnson Bay, sand wedges with unusually wide tops (3.9 m) extend down from a prominent erosion surface. The wedges grew vertically downward during deflation of the ground surface, and represent anti-syngenetic wedges. The distribution of sand veins and wedges within the sand sheets indicates that the existence of continuous permafrost during sand-sheet aggradation can be inferred confidently only during full-glacial conditions

The chronostratigraphy of Late Pleistocene glacial and periglacial aeolian activity in the Tuktoyaktuk Coastlands, NWT, Canada

Aeolian periglacial sand deposits are common in the Tuktoyaktuk Coastlands of Western Arctic Canada. Regionally extensive and thick aeolian sand-sheet deposits have been observed in two major stratigraphic settings: within a sand unit characterized by large aeolian dune deposits; and interbedded with glaciofluvial outwash from the Laurentide Ice Sheet (LIS). Small, localized sand sheets have also been observed along the tops of sandy bluffs, within sequences of drained thermokarst lakes deposits and as an involuted veneer above buried basal ice of the LIS. On the basis of radiocarbon and optically stimulated luminescence (OSL) dates from preserved periglacial aeolian sand sheets and dunes a regional chronostratigraphy is presented which indicates that both extensive dunes and sand sheets accumulated mainly between ca 30 and 13 ka. A switch to dominantly sand-sheet aggradation at ca 14–13 ka, with sand sheets forming widely until ca 8 ka, is attributed to (a) surface armouring by glacial deposits associated with the advance of the LIS; and (b) amelioration of the climate from cold aridity. An absence of OSL dates between ca 8 and 1 ka suggests that sand sheets stabilized during much of the Holocene. Local sand-sheet aggradation during recent centuries has occurred near sandy bluffs and on the floors of drained thermokarst lakes. The OSL dates constrain the maximum extent of the LIS in the Tuktoyaktuk Coastlands to Marine Isotope Stage 2

A guide to the translation of the Global Initiative for Asthma (GINA) strategy into improved care

In 1995, the Global Initiative for Asthma (GINA) published an evidence-based workshop report as a guide to clinicians managing asthma patients, and has updated it annually to ensure that recommendations remain current. Although the report has been widely disseminated and influenced clinical practice and research, its major objective, of forming the basis for local and national initiatives to improve services for asthma patients, remains to be achieved. Over recent years, the science of guideline implementation has progressed, and encouraging examples of successful asthma programmes have been published. This report is intended to draw on this experience and assist with the translation of asthma guideline recommendations into quality programmes for patients with asthma using current knowledge translation principles. It also provides examples of successful initiatives in various socioeconomic settings

Long View (41RB112): Data Recovery of Two Plains Village Period Components in Roberts County, Texas, Volume 1

This archeological data recovery investigation in Roberts County in the northeastern panhandle of Texas was necessitated by the proposed widening of State Highway 70 (CSJ: 0490-04-037) by the Texas Department of Transportation (TxDOT), Amarillo District. This proposed highway rehabilitation program will directly impact a roughly 10 meter (m, 30 ft.) wide north-south section of prehistoric site 41RB112, the Long View site. This site consists of two horizontally distinct Plains Village period occupations shallowly buried along a linear interfluvial ridge between two small tributary creeks to the Canadian River in the midslope of this broad, dissected valley. This site was initially discovered by TxDOT archeologist, Dennis Price in June 2004 during an archeological inventory of the proposed 9.7 kilometer (6 mile) section north of the Canadian River in response to the planned highway rehabilitation program. Based on Mr. Price’s discovery of multiple artifact classes in buried context he recommended this site be assessed for its eligibility for listing on the National Register of Historic Places under criterion d and possible designation as a State Archeological Landmark (SAL) per the requirements of Section 106 of the National Historic Preservation Act (NHPA) and other related legislation. Following the Texas Historical Commissions concurrence with that recommendation, TxDOT through the Environmental (ENV) Affairs Division, contracted to TRC Environmental Corporation (TRC) under an existing Scientific Services Contract No. 57XXSA006 and issued a Work Authorization to TRC of Austin to conduct the site eligibility assessment. During a site visit by TxDOT geoarcheologist James Abbott and TRC archeologist Mike Quigg in February 2005, the site boundaries were expanded to nearly 300 meters (m) along the proposed area of potential effect (APE). Investigative strategies were devised to assess the Long View site. In May 2005, TRC’s archeologists from Austin conducted archeological testing for a NRHP and SAL eligibility assessment investigation at 41RB112. The assessment along the 10-m-wide by 300-m-long APE was accomplished by hand-excavating 28 1-by-1 m units (totaling 16.8 m3), hand-excavating four narrow ca. 30 centimeter (cm) wide trenches (two in each area totaling nearly 32 linear meters), as well as cleaning and inspecting 28 m of existing road cut exposures. These investigations determined that cultural materials clustered at the northern and southern ends (Areas A and C respectively) of the site with nearly 120 m of noncultural bearing deposits (Area B) between the two concentrations. A 4-m-wide mechanically bladed fireguard paralleled the existing fenceline throughout the length of the APE and disturbed much of the near surface materials in that zone. The opposite, eastern side of the highway was investigated through the excavation of six 50-by-50 cm shovel tests, surface, and road cut inspection. Based on the results from the hand-excavations and various collections conducted during the site assessment, it became apparent that the two ends (Areas A and C) of the Long View site in TxDOT’s proposed APE contained well-defined cultural components in the top 50 cmbs. Each end appeared to represent habitation remains from single occupation episodes with potential structures, restricted to a narrow time period of less than 100 years between uncalibrated 630 and 710 B.P. of the Plains Village period. Rodent and natural disturbances had vertically displaced some small cultural objects within the sandy deposits, but the restricted period of occupation to roughly a 100 year period reduces this impact. TRC recommended the site was eligible for listing on the National Register and as a State Landmark. The Texas Historical Commissions concurred with that recommendation, and subsequently the ENV Affairs Division of TxDOT, again contracted to TRC under an existing Scientific Services Contract No. 575XXSA008 and issued a Work Authorization to TRC Austin to perform the mitigation of the proposed impacts. Data recovery investigations were conducted during August through November 2006 along the western side of the existing highway. The previously identified northern-Area A and southern–Area C areas with high concentrations of cultural materials were targeted. These investigations began with a thorough geophysical survey that employed three noninvasive electrical detective instruments across Areas A and C anticipating to detect the locations of subsurface cultural features to target by hand-excavations. Some excavations targeted the detected anomalies, whereas others targeted previously identified features. In the end, hand-excavated blocks were completed in Areas A and C. The excavations totaled 128 m2 in Area A and 93 m2 in Area C for a grand total of 221 m2 or 103.4 m3. In conjunction with the archeological excavations, geoarcheological investigations focused on defining the age and development of the natural Holocene sediments that contained the cultural materials. The geoarcheological assessment included detailed stratigraphic documentation of site and near site deposits, sediment texture characterization, soil thin sections, magnetic susceptibility, multiple chemical analyses (organic, calcium, and phosphorus). Detailed stratigraphic data was also collected at two rare pithouse structures to pursue construction and filling episodes. The excavations yielded significant and diverse cultural assemblages from the two occupations assigned Component A and C. Both components are attributed to the Plains Village period with two discrete occupations dating to uncalibrated 460 to 535 B.P. (cal A.D. 1398 to 1447) in Component A and 530 to 700 B.P. (cal A.D. 1280 to 1437) in Component C. The two assemblages are significant not only in their diversity and quality of materials but also in the information they yielded. This report represents one of the first complete documents to present the entire cultural assemblage from a single site for this time period and region. The total recovered assemblage includes 157 formal chipped and ground stone tools, 226 informal tools, 3,414 pieces of lithic debitage, over 6,400 faunal fragments (1.4 kg), some 1,541 ceramic sherds, 1,790 burned rocks, at least 116 macrobotanical samples that includes 16 maize cobs, two human burials, and remains of a third, juvenile scattered along a previously bladed fireguard, 32 intact cultural features that include two rare pithouses, and other cultural debris related to these two campsites. The human remains and associated artifacts will be repatriated in accord with the requirements of the Native American Graves Protection and Repatriation Act (NAGPRA). A suite of 10 technical analyses directed at mostly the cultural assemblages included; use-wear, phytolith, diatom, petrography, macrobotanical, starch grain, instrumental neutron activation, bison bone isotopes, obsidian sourcing, radiocarbon and optical stimulated dating. This data was used to address 11 specific research questions concerning these Plains Village period occupations. Not only does the cultural debris contribute to our understanding of the time period but the geoarcheological information obtained explains the conditions and how the materials were preserved, and inform us concerning the past depositional environment in this immediate area. The combined information contributes to a significant understanding to a specific part of the Plains Village cultures in the Texas panhandle. Following the acceptance of the final report by the TxDOT and the Texas Historical Commission these cultural materials and all the documentation from the combined investigations will be permanently curated at Texas State University in San Marcos, Texas. The curated materials will provide important data that can be researched by interested parties in the future

Aeolianite and barrier dune construction spanning the last two glacial-interglacial cycles from the southern Cape coast, South Africa

The southern Cape region of South Africa has extensive coastal aeolianites and barrier dunes. Whilst previously reported, limited knowledge of their age has precluded an understanding of their relationship with the climatic and sea-level fluctuations that have taken place during the Late Quaternary. Sedimentological and geomorphological studies combined with an optical dating programme reveal aeolianite development and barrier dune construction spanning at least the last two glacial–interglacial cycles. Aeolianite deposition has occurred on the southern Cape coast at ca 67–80, 88–90, 104–128, 160–189 and >200 ka before the present. Using this and other published data coupled with a better understanding of Late Quaternary sea-level fluctuations and palaeocoastline configurations, it is concluded that these depositional phases appear to be controlled by interglacial and subsequent interstadial sea-level high stands. These marine transgressions and regressions allowed onshore carbonate-rich sediment movement and subsequent aeolian reworking to occur at similar points in the landscape on a number of occasions. The lack of carbonates in more recent dunes (Oxygen Isotope Stages 1/2 and 4/5) is attributed not to leaching but to changes to carbonate production in the sediment source area caused by increased terrigenous material and/or changes in the balance between the warm Agulhas and nutrient-rich Benguela ocean current