Economic evaluation of diagnosing and excluding ectopic pregnancy

BACKGROUND: The diagnosis of ectopic pregnancy in women presenting in early pregnancy is often protracted, relying on costly investigations that are psychologically burdensome to the patient. The aim of this study was to evaluate the financial costs to the health services in Scotland of the current methods used to diagnose and exclude ectopic pregnancy, and compare these with that of a theoretical single diagnostic serum biomarker. METHODS: We conducted a retrospective cost description analysis (with and without costs of diagnostic laparoscopy) of the healthcare costs incurred by all patients presenting to a large Scottish teaching hospital between June and September 2006 with pain and bleeding in early pregnancy, where ectopic pregnancy was not excluded. Additionally, a cost minimisation analysis was performed of the costs of current ectopic pregnancy investigations versus those of a theoretical single diagnostic serum biomarker. This included sensitivity analyses where the biomarker was priced at increasing values and assumed to have less than 100% diagnostic sensitivity and specificity. RESULTS: 175 patients were eligible to be included in the analysis. 47% of patients required more than 3 visits to diagnose or exclude ectopic pregnancy. The total yearly cost for diagnosing and excluding ectopic pregnancy was £197K for the hospital stated, and was estimated to be £1,364K for Scotland overall. Using a theoretical diagnostic serum biomarker we calculated that we could save health services up to £976K (lowest saving £251K after subanalyses) every year in Scotland. CONCLUSIONS: Ectopic pregnancy is expensive to diagnose and exclude, and the investigation process is often long and might involve significant psychological morbidity. The development of a single diagnostic serum biomarker would minimise this morbidity and lead to significant savings of up to £1 million pounds per year in Scotland

The ‘mosaic habitat’ concept in human evolution: past and present

The habitats preferred by hominins and other species are an important theme in palaeoanthropology, and the ‘mosaic habitat’ (also referred to as habitat heterogeneity) has been a central concept in this regard for the last four decades. Here we explore the development of this concept – loosely defined as a range of different habitat types, such as woodlands, riverine forest and savannah within a limited spatial area– in studies of human evolution in the last sixty years or so. We outline the key developments that took place before and around the time when the term ‘mosaic’ came to wider palaeoanthropological attention. To achieve this we used an analysis of the published literature, a study of illustrations of hominin evolution from 1925 onwards and an email survey of senior researchers in palaeoanthropology and related fields. We found that the term mosaic starts to be applied in palaeoanthropological thinking during the 1970’s due to the work of a number of researchers, including Karl Butzer and Glynn Isaac , with the earliest usage we have found of ‘mosaic’ in specific reference to hominin habitats being by Adriaan Kortlandt (1972). While we observe a steady increase in the numbers of publications reporting mosaic palaeohabitats, in keeping with the growing interest and specialisation in various methods of palaeoenvironmental reconstruction, we also note that there is a lack of critical studies that define this habitat, or examine the temporal and spatial scales associated with it. The general consensus within the field is that the concept now requires more detailed definition and study to evaluate its role in human evolution

Sanidine, Single Crystal, Laser-Fusion 40Ar/39Ar Geochronology Database for the Superstition Volcanic Field, Central Arizona

The Superstition volcanic field or Superstition - Superior volcanic field (Sheridan, 1978) of central Arizona has had a long, complex history of geological investigation. Starting along its eastern edge with studies of the Globe-Miami copper district (Ransome, 1903) work has continued for nearly one hundred years mainly in the rugged Superstition Mountains along the eastern fringe of the Phoenix metropolitan area (eg. Peterson, 1960, 1968, 1969; Peterson and others, 1983; Stuckless and Sheridan, 1971; Sheridan and others, 1970; Sheridan, 1987; and Sheridan and Prowell, 1986). Investigations initiated in 1994 by the Arizona Geological Survey concentrated on detailed (1:24,000) mapping of 7.5' quadrangles in the Superior area, Whitlow Canyon area, Goldfield Mountains, Santan Mountains, Superstition Mountains, and along the lower Salt River Canyon (Figure 1). Early on in the investigation, it was determined that the area's stratigraphic framework was considerably different from previous interpretations and that the volcanic field's geochronology was poorly resolved. The previous stratigraphic framework and nomenclature was exceptionally complex (Skotnicki and Ferguson, 1995; Trapp, 1996). Previous workers (principally Stuckless and Sheridan, 1971; Sheridan, 1987) had concluded that the field included at least three large ash-flow tuff cauldrons and that the duration of volcanism spanned over 10 million years from the latest Oligocene (27 Ma) to middle Miocene (15 Ma).Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]

Eruptive environment of volcanism on Brabant Island: evidence for thin wet-based ice in northern Antarctic Peninsula during the Late Quaternary

Terrestrial volcanism occurred extensively on Brabant Island, northern Antarctic Peninsula, during the Late Quaternary (< 200 ka; probably entirely Late Pleistocene). Two compositionally distinct volcanic sequences formed three large shield volcanoes. The volcanoes were constructed in association with a < 150 m-thick, non-ice stream glacial cover, although it was likely to be thicker (few hundred metres) where it extended onto the continental shelf. The glacial cover on the volcanoes was probably mainly permeable snow, firn and fractured (crevassed) ice. It was wet-based, erosive and sediment-forming, indicating either a temperate or, perhaps more likely, sub-polar thermal regime, and would have been more extensive than that present today. Such a thin ice sheet would have had a low surface gradient during periods of extension across the continental shelf. This is the first direct evidence for the thickness and thermal regime of the terrestrial ice sheet in the Antarctic Peninsula during any Quaternary period prior to the last glacial maximum

Mid-Tertiary geology and geochronology of the Clifton-Morenci Area, Greenlee and Graham Counties, Arizona and adjacent New Mexico

The geology of the Clifton-Morenci area has been investigated for nearly 100 years beginning with the pioneering work of W. Lindgren at the start of the 20th century. For most of the century, geological investigation focused on mineralization and the complex suite of Eocene porphyritic intrusive stocks and dikes in the area. Very little attention was directed at the regional structural and stratigraphic relationships in the overlying, and largely unmineralized Tertiary volcanic rocks. From the beginning, geologists have understood that supergene enrichment played a critical role in making the Morenci district a world class porphyry copper deposit (Lindgren, 1905a). For much of the past 90 years, enrichment was thought to have occurred during two phases of exposure and erosion: pre-volcanic and post-volcanic (Lindgren, 1905a; Moolick and Durek, 1966; Langton, 1973; North and Preece, 1993). Since then, the role of pre-volcanic enrichment has been questioned (Cook, 1994; Enders, 2000). Understanding the evolution of supergene enrichment at Morenci is of critical importance, not only because of this deposit’s economic significance, but also in terms of our understanding of the evolution of porphyry copper systems in general. As a result, Phelps Dodge Morenci Inc. initiated a research program in 1997 to address unanswered questions concerning the Tertiary geologic history of the Clifton-Morenci area. The principal result of this effort was a Ph.D. program undertaken by M. Stephen Enders at the University of Arizona that included a re-examination of the regional structure and Tertiary stratigraphy of the Clifton-Morenci area. The detailed geologic map, structural cross-sections, and the stratigraphic, geochronologic, and structural observations contained in this report are the principal products of this aspect of the research program. (69 pages)Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]

The Cape Purvis volcano, Dundee Island (northern Antarctic Peninsula): late Pleistocene age, eruptive processes and implications for a glacial palaeoenvironment

Cape Purvis is a conspicuous promontory on southern Dundee Island. It forms a prominent mesa that contrasts with the smooth, shield-like (snow-covered) topography of the remainder of the island. The promontory is composed of fresh alkaline basaltic (hawaiite) volcanic rocks compositionally similar to younger lavas on Paulet Island 5 km to the east. The outcrop is one of the youngest and northernmost satellite centres of the James Ross Island Volcanic Group. 40Ar/39Ar isotopic dating indicates that the Cape Purvis volcano is 132 ± 19 ka in age. The examined sequence probably formed as a lava-fed delta during a subglacial eruption late in the glacial period corresponding to Isotope Stage 6, when the ice sheet surface elevation was 300–400 m higher than at present. A remarkable unidirectional age progression is now evident, from volcanic centres in Prince Gustav Channel (c. 2.0–1.6 Ma), through Tabarin Peninsula (1.69–c. 1 Ma) to Cape Purvis and Paulet islands (132–few ka). The age variations are tentatively ascribed to construction of progressively younger volcanic centres at the leading edge of an easterly-opening deep fault system, although the origins of the postulated fault system are unclear

Late Neogene interglacial events in the James Ross Island region, northern Antarctic Peninsula, dated by Ar/Ar and Sr-isotope stratigraphy

New outcrops of Late Neogene sedimentary deposits discovered on James Ross and Vega islands, northern Antarctic Peninsula, are fossiliferous and contain mainly fragmented pectinids amongst other as yet unstudied biota. The sedimentary deposits are interbedded with fresh volcanic units, thus providing the unusual opportunity to investigate the ages of the sedimentary rocks using two independent isotopic systems (40Ar/39Ar and 87Sr/86Sr). The fossils record past periods of warmer conditions (interglacials) like today. However, our results demonstrate unequivocally that some of the macrofossils present in the sedimentary rocks are reworked and the host sediments are, in these cases, much younger than the ages of their included fossils would suggest. Nevertheless, the Sr ages date these records of interglacial events in the region independently of the age of the strata in which they occur. Conversely, the volcanic rocks show abundant field evidences that they are coeval with the underlying sedimentary deposits, and hence their Ar ages reliably date the timing of their deposition. Our results indicate that at least three generally warmer periods are represented in the James Ross Island region: at 6.5–5.9, 5.03–4.22 and< 0.88 Ma, although our data do not have the resolution for identifying Milankovitch-scale cyclicity. However, the Early Pliocene warm period is particularly well represented and the James Ross Island data may well be capturing a higher proportion of the longer-lasting interglacials that characterised that period. We also present evidence for an interglacial in the Late Pliocene (at 2.54 + 0.86/− 0.36 Ma). Our data suggest that both Antarctic Peninsula and the East Antarctic ice sheets responded in a similar way to long-term regional shifts in climate, but the Antarctic Peninsula is more sensitive to short-term warming, as occurs today