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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.
Field observations indicate that sulfonylurea-resistant kochia may germinate at lower soil temperatures and/or germinate more rapidly than susceptible kochia in the absence of herbicide. To investigate this possibility, seeds from three resistant and two susceptible kochia accessions were germinated at temperatures ranging from 4.6 to 13.2 C on thermal gradient plates. At 4.6 and 13.2 C, germination rates of all resistant accessions were higher than susceptible accessions, while germination rates of one resistant accession were higher than susceptible accessions at 7.2 and 10.5 C. Percent germination of all resistant accessions was significantly higher than susceptible accessions after 48 h at 4.6 C. At higher temperatures, percent germination of some resistant accessions was higher after 12 or 24 h, but germination of all accessions was similar at later times. HPLC analysis revealed that seeds from resistant accessions contained about 2-fold higher free levels of branched chain amino acids than seeds from susceptible accessions. The results indicate that mutations conferring resistance to sulfonylurea herbicides in these kochia accessions may concomitantly reduce or abolish acetolactate synthase sensitivity to normal feedback inhibition patterns, resulting in elevated levels of branched chain amino acids available for cell division and growth during early germination.
Repeated use of the preemergence herbicide triallate has selected for wild oat populations that are resistant (R) to field use rates. Field collections and an inbred R line were shown in greenhouse and petri dish dose response experiments to be 6- to 20-fold more tolerant to triallate than susceptible (S) lines. R populations and the inbred line were also resistant (8-fold) to the related thiocarbamate herbicide diallate, as well as to the chemically unrelated postemergence herbicide difenzoquat (60-fold). 14C-triallate uptake and translocation patterns were similar between R and S lines for the first 24 h after application. However, translocation of radioactivity was more rapid in S lines than R lines from 24 through 60 h after application. 14C-difenzoquat uptake was the same in R and S lines 12 h after application, but was 10 to 20% higher in R lines than S lines by 24 through 96 h after application. Similarly, translocation of radioactivity after 14C-difenzoquat application was 7 to 14% greater in R than S lines after 12 h, although translocated radioactivity amounts were not significantly different between R and S lines. The relatively minor differences in triallate and difenzoquat uptake and translocation patterns between R and S lines are most likely not of sufficient magnitude to explain the observed resistance levels.
Kochia pollen dispersion was measured during 24 and 48 h periods from a kochia population in an 8- by 10-m area in the center of a 1.6 ha fallow field. Pollen counts from traps at 50- and 100-cm heights declined rapidly with increasing distance from the pollen source. Pollen deposition was highest along the prevailing wind direction: up to 23 pollen grains cm–2 were recovered 50 m from the pollen source along the southeast (SE) vector. Nonlinear regression analysis of pollen deposition along the SE vector was used to estimate that 99.9% of shed pollen would be deposited within 154.4 m of the source. Viability of pollen from greenhouse- and field-grown plants was measured using staining and germination assays. of four pollen stains tested, only 1,2,3-triphenyl tetrazolium chloride gave consistent results and did not stain heat-killed pollen. Depending on environmental conditions, kochia pollen remained viable from less than 1 d to 12 d. Length of kochia pollen viability was shortest under high temperatures (22 and 28 C) and low relative humidity (7 and 32%). Less than 0.5% germination was observed in 1.1% agar media with various additions; however, up to 17.8% germination was observed after incubation at 28 C in 100% relative humidity.
The discovery of evidence to suggest that copper ore was exploited at the Great Orme on a considerable scale in prehistory is of great significance in our understanding of the development of metalworking technology in the British Isles.
In the past, the apparent absence from the archaeological record of a contemporaneous native mineral source for the production of copper and copper alloy artefacts during the Bronze Age has led to the assumption that raw materials, as well as metal technology, were imported from abroad. Alternatively, whilst accepting that local resources could have been exploited, it was assumed that these would have been obliterated by the mining operations of later centuries.
There are now several sites on the British mainland and in Ireland which have been identified and dated as having been exploited for copper ores during the Bronze Age, of which a number, as on the Great Orme, had since seen intensive working during the 18th and 19th centuries AD. AS yet, much of the evidence has come essentially from surface excavations, but at the Great Orme surface excavation combined with underground exploration has revealed a system of workings of truly remarkable size. A series of 10 radiocarbon dates has been obtained from within the mine complex, indicating that working was carried out for over a thousand years spanning the Early to Late Bronze Age.
The true extent of the surviving prehistoric workings is yet to be realized but present evidence indicates mining activity covering an area in excess of 24,000 square metres, incorporating passages totalling upwards of 5 km, penetrating to a vertical depth of 70 m.
Much of the archaeological evidence contained within this report has been gained from detailed excavation carried out within surface workings, which in their own right constitute a sizeable part of the prehistoric mine. From the surface area presently exposed it is conservatively estimated that 40,000 cubic metres of material was removed during the Bronze Age. Much of the early technology represented within the surface workings reflects the technology employed in the deep workings, with the additional evidence of ancillary operations which would seem to relate solely to surface locations.
Whilst the excavations reported in this paper relate to surface, or near surface, workings, they must be seen in the context of a labyrinthine complex of prehistoric workings recorded at depths of over yom (Jenkins & Lewis 1991; Lewis 1994). These deep workings are the subject of parallel studies to be reported elsewhere. The known underground and surface prehistoric workings are on a scale so far unparallelled in Britain and are of international significance. Elsewhere in Europe there is evidence for the mining of copper ores at Ai Bunar in Bulgaria dated to 5840 BC (Cernych 1978) and at Rudna Glava in former Yugoslavia dated to 4715 BC (Jovanovic 1979). Evidence for subsequent copper mining has been dated to 3785 BC in southern Spain (Rio Tinto area: Rothenburg & Blanco Freijeiro 1980) and to 3330 BC in Austria (Mitterberg; Pittioni 1951), marking an apparent development and extension westwards and northwards of copper technology. More recently, the dating of two sites in the south of France to around 3330 BC, at Cabrieres (Ambert et al. 1990) and Bouche Payrol, near Brusque (Barge 1985), has confirmed another area of Bronze Age working.
Forty-four schizophrenic patients were followed up for five years after their first admission to hospital for a first episode of illness. Thirteen (30%) of 43 patients had not relapsed; 28 of the 30 patients who did relapse did so within the first 42 months. The relapses occurred despite antipsychotic drug therapy. Also, 24% of patients had at least one course of ECT. Only 19% of the patients at five years were in open employment; unemployment was strongly associated with relapse. Eighteen per cent had neither relapses nor schizophrenic symptoms at follow-up. Poor outcome at five years was associated with greater psychological distress among relatives at first admission. At five years 43% of relatives continued to show case level psychological stress.
This is the initial report of a prospective study by computerised tomography brain scan of first episode schizophrenia. Twenty-seven patients who met Research Diagnostic Criteria for schizophrenia were compared with volunteer controls on ventricular: brain ratio, sulcal: brain volume ratio, and the widths of third ventricle and Sylvian and interhemispheric fissures. The results provide evidence that sulcal enlargement, but not ventricular abnormalities, may be detected at first admission for schizophrenic illness, and are discussed in relation to findings from other studies.
Of 49 schizophrenic patients followed up 12 months after their first admission to hospital, only about 45% had experienced no relapse and had no schizophrenic symptoms; a poorer outcome was more often found in Feighner positive than Feighner negative schizophrenic patients. The patients' overall level of unemployment had more than doubled to 51%. In patients whose acute episodes responded to treatment, pimozide taken once weekly as maintenance therapy was as effective as intramuscular flupenthixol decanoate, but tardive dyskinesia appeared in two patients receiving weekly pimozide; the repeat psychometric assessment at 12 months found modest improvements, i.e. no evidence of intellectual decline, in Matrices, Block Design, and Digit Copying tests. Forty per cent of relatives still showed significant psychological distress, which correlated with patients' schizophrenic symptoms, and the relatives' social functioning remained poorer than that of a normal community sample.
An assessment of 31 main care-giving relatives living with schizophrenics was carried out using the General Health Questionnaire and the Social Adjustment Scale by Self Report. More than 75% of relatives had a high probability of themselves being a psychiatric case. Relatives also showed social role dysfunction and impairment especially marked in social and leisure activities. Relatives' distress was related to the level of symptoms in patients, as assessed by the Present State Examination.
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