The first demonstration of laser action in ruby was made in 1960 by T. H. Maiman of Hughes Research Laboratories, USA. Many laboratories worldwide began the search for lasers using different materials, operating at different wavelengths. In the UK, academia, industry and the central laboratories took up the challenge from the earliest days to develop these systems for a broad range of applications. This historical review looks at the contribution the UK has made to the advancement of the technology, the development of systems and components and their exploitation over the last 60 years.

Starbursts are finite periods of intense star formation (SF) that can dramatically impact the evolutionary state of a galaxy. Recent results suggest that starbursts in dwarf galaxies last longer and are distributed over more of the galaxy than previously thought, with star formation efficiencies (SFEs) comparable to spiral galaxies, much higher than those typical of non-bursting dwarfs. This difference might be explainable if the starburst mode is externally triggered by gravitational interactions with other nearby systems. We present new, sensitive neutral hydrogen observations of 18 starburst dwarf galaxies, which are part of the STARburst IRregular Dwarf Survey (STARBIRDS) and each were mapped with the Green Bank Telescope (GBT) and/or Parkes Telescope in order to study the low surface brightness gas distributions, a common tracer for tidal interactions.

Terrestrial gastropods are problematical for radiocarbon (14C) measurement because they tend to incorporate carbon from ancient sources as a result of their dietary behavior. The 14C ecology of the pulmonate land snail, Helix melanostoma in Cyrenaica, northeastern Libya, was investigated as part of a wider study on the potential of using terrestrial mollusk shell for 14C dating of archaeological deposits. H. melanostoma was selected out of the species available in the region as it has the most predictable 14C ecology and also had a ubiquitous presence within the local archaeology. The ecological observations indicate that H. melanostoma has a very homogenous 14C ecology with consistent variations in F14C across sample sites controlled by availability of dietary vegetation. The majority of dated specimens from non-urbanized sample locations have only a small old-carbon effect, weighted mean of 476±48 14C yr, with between ~1% and 9% of dietary F14C from non-organic carbonate sources. Observed instabilities in the 14C ecology can all be attributed to the results of intense human activity not present before the Roman Period. Therefore, H. melanostoma and species with similar ecological behavior are suitable for 14C dating of archaeological and geological deposits with the use of a suitable offset.

This paper explores how race/ethnicity and perceptions of racial discrimination and inequality shape beliefs about the implications of an Obama presidency for U.S. race relations. Specifically, using data from a June/July 2008 Gallup/USA Today survey, we examine how African Americans, Hispanics, and Whites differ in their perceptions of the importance of an Obama victory and in beliefs about the implications of such for race relations, racial progress, and opportunities for Blacks in their careers and in national politics. We also examine how perceptions of the extent and nature of racial discrimination and inequality shape these outcomes (overall and by race/ethnicity). Results show that African Americans, relative to Whites and Hispanics, are especially likely to see an Obama victory as important and meaningful in terms of relatively abstract notions of racial change. In contrast, Hispanics are more likely than African Americans and Whites to believe that an Obama win will translate into concrete societal changes, such as expanded opportunities for Blacks in work and politics. In addition, perceived discrimination and inequality positively shape all of the outcomes under study (more perceived discrimination equals more importance and optimism attached to an Obama win), though this association is especially strong among Whites—a pattern possibly rooted in divergent meanings attached to perceived discrimination and inequality by race/ethnicity. Overall, our findings suggest that African Americans view an Obama victory as meaningful primarily because of its symbolic significance, rather than because they believe it will result in substantive racial progress. We conclude by offering some speculation and selected questions for future research on race and U.S. politics.

Investigation of a section near Morston on the central north Norfolk coast has revealed evidence of a complex sequence of beach deposits laid down under interglacial conditions in association with relative sea levels similar to those of the present. This material rests upon a highly calcareous till and is itself overlain by a deposit comparable with the Hunstanton Till of northwest Norfolk. This site therefore represents the first location at which Hunstanton Till has been found overlying older till, and the only location so far discovered in East Anglia at which interglacial deposits separate glacigenic sediments. The site also contains the only indubitable Quaternary warm stage deposits to have been recognized in central north Norfolk.

Ammonites and palynology are described at the Portland-Purbeck junction in the Weald. A major disconformity exists between glaucolithus Zone Portland Beds and the overlying basal Purbeck facies, the basal Purbeck Beds of the Weald are correlated with the Middle Purbeck strata of Dorset. The Cinder Bed of Dorset and Wiltshire is described as one of several marine incursions entering Wessex from further south in the Anglo-Paris basin, not from the Spilsby basin. The use of Cinder Bed as a convenient Jurassic-Cretaceous (Portlandian-Ryazanian) boundary is critically reviewed, as is the placing of the base of the Berriasian Stage in the type Purbeck section. The rival biostratigrahic schemes based on ostracods and palynology are discussed and the discrepancies between the two schemes in southern England are examined.

Tràng An is a Vietnamese government supported cultural and ecological park development covering 2,500 hectares that is centred on an isolated massif on the southern edge of the Song Hong delta in Ninh Bình Province, north Vietnam (Fig. 1). The archaeological investigation of Tràng An is being led jointly by the Xuan Truong Construction Corporation and the McDonald Institute for Archaeological Research, University of Cambridge, under the direction of the lead author. The Corporation is creating an ecologically sensitive development – the ‘Tràng An Tourism Resort’ – within this karstic landscape, which is also the subject of a planned application to UNESCO for World Heritage Site status. International involvement in this work has been at the behest of Nguyêń Van Truong, the General Director of Xuan Truong and at the invitation of the Ninh Bình People's Committee. The research itself is carried out under the guidance of Nguyêń Van Son, the Tràng An Tourism Resort Project Manager. The main focus of the May 2007 season was to undertake excavations at the site of Hang Boi (the ‘Fortune-Teller's Cave’).

Summary

Background and objective: The study was designed to identify those factors associated with early tracheal extubation following cardiac surgery. Previous studies have tended to concentrate on surgery for coronary artery bypass or on other selected cohorts.

Methods: Sequential cohort analysis of 296 unselected adult cardiac surgery patients was performed over 3 months.

Results: In total, 39% of all patients were extubated within 6 h, 89% within 24 h and 95% within 48 h. Delayed extubation (>6 h after surgery) appeared unrelated to age, gender, body mass index, a previous pattern of angina or myocardial infarction, diabetes, preoperative atrial fibrillation, and preoperative cardiovascular assessment, as well as other factors. Delayed tracheal extubation was associated with poor left ventricular, renal and pulmonary function, a high Euroscore, as well as the type, duration and urgency of surgery. Early extubation (<6 h) was not associated with a reduced length of stay in either the intensive care unit or in hospital compared with patients who were extubated between 6 and 24 h. In these groups, it is presumed that organizational and not clinical factors appear to be responsible for a delay in discharge from intensive care. Patients who were extubated after 24 h had a longer duration of hospital stay and a greater incidence of postoperative complications. Postoperative complications were not adversely affected by early tracheal extubation.

Conclusions: In an unselected sequential cohort, both patient- and surgery-specific factors may be influential in determining the duration of postoperative ventilation of the lungs following cardiac surgery. In view of the changing nature of the surgical population, regular re-evaluation is useful in reassessing performance.

This paper describes an integrated series of sedimentological and palynological studies of the arenaceous deposits which infill the large alluvial basin of Grerat D'nar Salem, which is located on a limestone plateau in the semi-arid pre-desert of Tripolitania north-west of the town of Beni Ulid. This research shows that in the early and middle Holocene this depression was occupied by a large semi-permanent or permanent water body which was surrounded by a grass-steppe vegetation with some tree and shrub species, perhaps growing in wetter stream- and wadi-beds. Sometime in the mid-Holocene the region became much more arid, the lake disappeared, matching the pattern of environmental change observed elsewhere in northern Africa. The geomor-phic environment became dominated by aeolian processes, interrupted by occasional winter floods, in a landscape dominated by grass steppe — essentially the situation that has continued to the present day. It is clear from general biogeographical and geomorphic considerations that Romano-Libyan floodwater farming in the region must have brought about significant changes in the character of wadi floors. Field survey indicates that it has also left a legacy in the contemporary distribution of plants, animals and runoff in the modern landscape. Nevertheless, no clear evidence has emerged from this study that the widespread and intensive flood-water farming, evidenced by the archaeological remains in the area, was associated with either a climate or a landscape notably different from that of today. The new palynological evidence suggests that the nature of the related ancient cultivation at Grerat is better viewed as a monoculture, rather than the mixed farming deduced previously for wadi-floor areas. There is no evidence that any naturally-occurring environmental change was associated with the introduction or loss of floodwater farming in the region. There is some sedimentological evidence that such activity might have led to problems of soil salinity in this basin.

The description and analysis of particle size distributions using log skew Laplace distributions is a new technique designed to overcome various mathematical and computational problems associated with other approaches. This paper presents an application of the method. In particular, it describes fitting log skew Laplace distributions to modern and ancient shoreline sands from Lepcis Magna (near Horns), Tripolitania, with the purpose of discriminating between modern environments and so classifying the ancient samples. Satisfactory discrimination was not always achieved between some of the modern ‘calibration’ shoreline sand samples of known provenance — possibly as a result of the presence of multimodal distributions. One layer in the harbour-infill sequence, previously of unknown provenance, was shown to have collected at, or close to, an ancient shoreline which developed within the ancient harbour. The majority of the ‘ancient’ samples of unknown depositional environments which were excavated from exposures in the Romano-Libyan harbour-infill sands, were shown by this analysis to be of neither beach nor aeolian origin. This conclusion supports field observations which suggested that the greater part of the harbour-infill sequence represented reworked dune palaeosols, developing dune soils and fluvial and lagoonal facies.

Volume 52 of the Proceedings of the Prehistoric Society contained two articles (Salisbury 1986; Tipping 1986) critical of our paper ‘The stratigraphy of Kirkhead Cave, an upper palaeolithic site in northern England’ (Gale and Hunt 1985). Here we reply.

Before dealing with the criticisms made by Salisbury, we correct the factual errors in his paper.

1. Bolton and Morris ‘… excavated through, and ultimately removed some 5 to 7 metres of cave earth…’ (Salisbury 1986, 321). In fact, the reports indicate a maximum depth of excavation of 7 ft (2.1 m) (Bolton 1864, cclii) or 8 ft (2.4 m) (Morris 1865–66, 360, 361; 1866, 169, 170; Bolton 1869, 167–68).

2. Bolton and Morris's ‘… publications are of little value today, and both may be considered to have been “bone hunters” and collectors’ (Salisbury 1986, 321). The assertion that Bolton and Morris's excavation reports are of little value suggests that Salisbury is not familiar with the wealth of early literature on this site. The reports provide a picture of a rich and varied assemblage of artefacts and macrofauna in the unit overlying the stalagmite floor in the cave. Information is also provided on the lithology of that unit. Interpretation of these reports allows the reconstruction of the stratigraphic context of the finds: we direct Salisbury's attention to Gale and Hunt (1985, 296–97) for an indication of the stratigraphic reconstruction possible from the information given in these early publications.

White surface encrustations developing on basalt which had the same ‘reflectance signature’ on digital Landsat imagery as that from the limestone terrain in the Tripolitanian pre-desert are shown at the Wadi Gobbeen to be the thalli of the crustose lichen of the genus Aspicilia. The reproductive structures and ascospores of the lichen are described. The lichen is seen to be aiding the weathering and disintegration of the basalt cobbles. The absence of the thalli on the sides and underneath of cobbles currently resting upon the present land surface may suggest that soil erosion has been rapid in the recent past.

The Romano-Libyan farm Lm4 includes a ‘barrage’, water control walls and farm buildings. These were built as part of an agro-hydrological farm system at the confluence of the Wadi el Amud and the Wadi Umm el Bagul in the Libyan pre-desert. The farm appears to have functioned in a geomorphological environment not dissimilar to that which prevails today — with occasional rain storms producing overland flow and floods interrupting a dominance of aeolian processes. Field mapping revealed that substantial scatters of midden made up of abraded pottery, bone, and animal dung occur around the buildings. Animals appear to have been kept near to these buildings, which lead to coprolites becoming a very important component of these anthropogenic sediments. Such activity gave rise to significant bioturbation of the sediments, and a notable former vegetation cover. The petrology of the building stones used in the farm buildings is described using petrographic thin section studies. Cavernous weathering and case-hardening are shown to have developed after the stone was incorporated within the building. The size and distribution of these features are shown to relate to the nature of the bedrock used — especially the form and distribution of joints and sedimentary parting planes — as well as the distribution and thickness of the surficial soils and sediments, and the shape and form of the building.

A geological reconnaissance of the Beni Ulid — Wadi Merdum region of the pre-desert of Tripolitania shows that at least twenty, stratigraphically distinct geomorphic events can be recognised from field exposures, field mapping and the analysis of Spacelab metric camera photography. The earliest events are provisionally attributed to the early Cenozoic and include uplift, tilting, faulting, the formation of karstic and karst-tectonic landforms, and erosion by meandering river systems. Some of these valleys were infilled with lava flows from the south-south-west in the ?late Palaeocene/early Eocene. Re-excavation of the ancient landscape by rivers followed. Pleistocene deposits of powerful, often braided rivers occur in the wadi floor. The wadi sides are clothed in complex sequences of alluvial fans, screes, windblown, waterlain and anthropogenic deposits, sometimes with weathering horizons and calcretes of uncertain stratigraphic significance. The plateaux contain large alluvial basins, palaeosols, soils and weathering horizons of uncertain age. Accelerated soil erosion caused by human activity appears to have been important in the area — slope deposits of scree and midden between 4 and 8 metres in thickness have accumulated beneath one gasr during a 500 year period. The most recent deposits identified are complex aeolian deposits at the wadi edge and the interdigitating series of floodloams and aeolian sands on the wadi floors.

This study documents the sediments, pollen, seeds, molluscs, vertebrates and mineral magnetism of deposits found in an abandoned water supply system at gasr Mm 10 in the Wadi Mimoun in the pre-desert of Tripolitania. These new data suggest (1) at or close to an episode of probable abandonment of that gasr, the growth of cereals (and perhaps general agricultural activity) still occurred on the wadi catchment upstream of the gasr, and (2) the vegetation of the adjacent wadi floor was richer in species (which included olive) than occurs today.

This paper describes the Quaternary geology of the area around Gasr Banat which lies near the confluence of the Wadis N'f'd and N'fed in the pre-desert of Tripolitania. The site is of interest because of its aridity, the notable archaeological remains that occur in the region and the opportunity it offered to map the surficial deposits of an area otherwise largely unknown. The survey revealed that two Pleistocene cobble and gravel units laid down by ‘torrential’ rivers could be distinguished: the older of which had been cemented by calcrete. Polyphase slope deposits occur. Thin section studies of the calcrete suggests it is possible to recognise two arid and two humid episodes from its micromorphology.

The Holocene period is represented by water-lain and aeolian deposits on the wadi floodplain, and climbing and barchan dunes on the adjacent hills. The period immediately prior to the construction of major cross wadi barrages may have been characterised by larger or more frequent floods than occurred immediately prior to the 1984 survey; the palaeoclimatic significance of this observation is unclear. One major barrage in the area is shown to have been built on substantial earth foundations. The assumed Romano-Libyan date of these barrages still remains to be proven, but, conversely, it is now demonstrated that they were not constructed or reconstructed in the 1950s.

Sediments of ?Pleistocene and Holocene age infilling an ancient irrigation channel adjacent to the Wadi Gobbeen in Tripolitania are described. The irrigation channel is part of a Romano-Libyan floodwater-farming system. Techniques for estimating the hydrological characteristics of floodwater-farming systems are applied to the irrigation channel to provide an indication of the water-carrying capacity of ancient floodwater-farming systems in the Libyan pre-desert.