Anthropogenic 14C in the Natural (Aquatic) Environment

Increasing global awareness of the radiological significance of 14C releases from the nuclear and radiochemical industries has resulted in a number of studies within the last decade investigating the atmospheric releases and their effect on the terrestrial biosphere. However, liquid discharges also occur, with preliminary studies indicating enriched 14C specific activities present in fish and shellfish harvested in the vicinity of discharge locations. The basis of this study was to determine the behaviour and environmental distribution of anthropogenically produced 14C released to the aquatic environment from the nuclear fuel reprocessing plant at Sellafield, owned by British Nuclear Fuels and the radiochemical plants in Cardiff and Buckinghamshire owned by Amersham International plc. Most sampling was undertaken in the Irish Sea with smaller scale studies being carried out in the Bristol Channel and the Grand Union Canal. Within the study area, from Earnse Point 40 km south of Sellafield, northwards to the Clyde Sea area, preliminary studies on intertidal biota samples ie. mussels, winkles and seaweed indicated enriched 14C specific activities in all the samples relative to the current ambient level of 115.4 pM. The highest activities were observed in the immediate vicinity of the discharge location; mussels with a measured activity of 787 pM, winkles of 613 pM and seaweed of 415 pM. The 14C specific activity observed at most sites appeared to be organism dependent with mussels>winkles>seaweed. This is the result of differences in the uptake mechanisms of the organisms and indicates that the dissolved inorganic carbon and the particulate material within the water column are enriched in 14C. However, on analysis of the biogeochemical fractions of the water column, enriched 14C activities were observed only in the DIC fraction which could explain those activities found in the seaweed but not those in the mussels and winkles. Enriched 14C activities were found in the phytoplankton, indicating that there is a source of enriched organic particulate material within the water column as a result of photosynthetic uptake of enriched DIC, however this will be a seasonal effect. Nevertheless, this enrichment is still not high enough to support the activities observed in the mussels and winkles, although, this was only a single sample and may not be a true reflection of the activities present. A similar anomaly is present in the activities found in bottom-dwelling fish and the sediments on which they feed; the fish are more highly enriched than the organic fraction of the sediments. These discrepancies may point to higher discharges having occurred in the past and/or to areas within the Irish Sea which are of a more enriched nature and were not investigated during this study. Prior to 1985, the discharges of 14C from Sellafield were not monitored and hence are merely best estimates. A temporal study of Nori (Porphyra umbilicalis) samples collected within the period 1967 - 1988 were analysed in an attempt to confirm these estimates. To ensure that Nori did reflect past discharges, 137Cs and 241Am were also analysed. The agreement observed between the 137Cs and 241Am discharges and measured activities was excellent, indicating that Nori did reflect Sellafield discharges. However, a similar agreement was not obtained for 14C, suggesting that either the estimated discharges are incorrect or that due to biological activity, Nori does not reflect 14C discharges in the same way that it does for 137Cs and 241Am. The geographical distribution of Sellafield-derived C in the DIC was determined by extensive sampling within the Irish Sea and Scottish coastal water areas. 137Cs, a known conservative radioactive tracer of water movement, was also analysed at the sites to allow comparison with the chemical behaviour of 14C. The results indicate that the behaviour of 14C in seawater, like that of 137Cs, is largely conservative. There was, however, a slight increase in the 14C/137Cs ratio with increasing distance from Sellafield. This may be a reflection of biological uptake of carbon or the desorption of 137Cs from the sediments. A more complex treatment of the data was carried out using a compartmental model, based on the hydrography of the study area, which was initially developed from 137Cs data. The agreement between the predicted and observed values indicates that the 14C distribution (as DIC) is being determined by water movement and the local current system ie. 14C in the DIC is behaving in a relatively conservative manner in the water column

What is the contribution of physician associates in hospital care in England? A mixed methods, multiple case study.

OBJECTIVES: To investigate the deployment of physician associates (PAs); the factors supporting and inhibiting their employment and their contribution and impact on patients' experience and outcomes and the organisation of services. DESIGN: Mixed methods within a case study design, using interviews, observations, work diaries and documentary analysis. SETTING: Six acute care hospitals in three regions of England in 2016-2017. PARTICIPANTS: 43 PAs, 77 other health professionals, 28 managers, 28 patients and relatives. RESULTS: A key influencing factor supporting the employment of PAs in all settings was a shortage of doctors. PAs were found to be acceptable, appropriate and safe members of the medical/surgical teams by the majority of doctors, managers and nurses. They were mainly deployed to undertake inpatient ward work in the medical/surgical team during core weekday hours. They were reported to positively contribute to: continuity within their medical/surgical team, patient experience and flow, inducting new junior doctors, supporting the medical/surgical teams' workload, which released doctors for more complex patients and their training. The lack of regulation and attendant lack of authority to prescribe was seen as a problem in many but not all specialties. The contribution of PAs to productivity and patient outcomes was not quantifiable separately from other members of the team and wider service organisation. Patients and relatives described PAs positively but most did not understand who and what a PA was, often mistaking them for doctors. CONCLUSIONS: This study offers new insights concerning the deployment and contribution of PAs in medical and surgical specialties in English hospitals. PAs provided a flexible addition to the secondary care workforce without drawing from existing professions. Their utility in the hospital setting is unlikely to be completely realised without the appropriate level of regulation and authority to prescribe medicines and order ionising radiation within their scope of practice

Biomechanics for inclusive urban design : effects of tactile paving on older adults’ gait when crossing the street

In light of our ageing population it is important that the urban environment is easily accessible and hence supports older adults’ independence. Tactile ‘blister’ paving was originally designed to provide guidance for visually impaired people at pedestrian crossings. However, as research links irregular surfaces to falls in older adults, such paving may have an adverse effect on older people. We investigated the effects of tactile paving on older adults’ gait in a scenario closely resembling “crossing the street”. Gait analysis of 32 healthy older adults showed that tactile, as compared to smooth, paving increases the variability in timing of foot placement by 20%, thereby indicating a disturbance of the rhythmic gait pattern. Moreover, toe-clearance during the swing phase increased by 7% on tactile paving, and the ability to stop upon cue from the traffic light was compromised. These results need to be viewed under consideration of the limitations associated with laboratory studies and real world analysis is needed to fully understand their implications for urban design

The Waipounamu Erosion Surface: questioning the antiquity of the New Zealand land surface and terrestrial fauna and flora

The Waipounamu Erosion Surface is a time-transgressive, nearly planar, wave-cut surface. It is not a peneplain. Formation of the Waipounamu Erosion Surface began in Late Cretaceous time following break-up of Gondwanaland, and continued until earliest Miocene time, during a 60 million year period of widespread tectonic quiescence, thermal subsidence and marine transgression. Sedimentary facies and geomorphological evidence suggest that the erosion surface may have eventually covered the New Zealand subcontinent (Zealandia). We can find no geological evidence to indicate that land areas were continuously present throughout the middle Cenozoic. Important implications of this conclusion are: (1) the New Zealand subcontinent was largely, or entirely, submerged and (2) New Zealand's present terrestrial fauna and flora evolved largely from fortuitous arrivals during the past 22 million years. Thus the modern terrestrial biota may not be descended from archaic ancestors residing on Zealandia when it broke away from Gondwanaland in the Cretaceous, since the terrestrial biota would have been extinguished if this landmass was submerged in Oligocene–Early Miocene time. We conclude that there is insufficient geological basis for assuming that land was continuously present in the New Zealand region through Oligocene to Early Miocene time, and we therefore contemplate the alternative possibility, complete submergence of Zealandia

Accelerated hyperfractionation (AHF) compared to conventional fractionation (CF) in the postoperative radiotherapy of locally advanced head and neck cancer: influence of proliferation

Based on the assumption that an accelerated proliferation process prevails in tumour cell residues after surgery, the possibility that treatment acceleration would offer a therapeutic advantage in postoperative radiotherapy of locally advanced head and neck cancer was investigated. The value of Tpot in predicting the treatment outcome and in selecting patients for accelerated fractionation was tested. Seventy patients with (T2/N1–N2) or (T3-4/any N) squamous cell carcinoma of the oral cavity, larynx and hypopharynx who underwent radical surgery, were randomized to either (a) accelerated hyperfractionation: 46.2 Gy per 12 days, 1.4 Gy per fraction, three fractions per day with 6 h interfraction interval, treating 6 days per week or (b) Conventional fractionation: 60 Gy per 6 weeks, 2 Gy per fraction, treating 5 days per week. The 3-year locoregional control rate was significantly better in the accelerated hyperfractionation (88±4%) than in the CF (57±9%) group, P=0.01 (and this was confirmed by multivariate analysis), but the difference in survival (60±10% vs 46±9%) was not significant (P=0.29). The favourable influence of a short treatment time was further substantiated by demonstrating the importance of the gap between surgery and radiotherapy and the overall treatment time between surgery and end of radiotherapy. Early mucositis progressed more rapidly and was more severe in the accelerated hyperfractionation group; reflecting a faster rate of dose accumulation. Xerostomia was experienced by all patients with a tendency to be more severe after accelerated hyperfractionation. Fibrosis and oedema also tended to be more frequent after accelerated hyperfractionation and probably represent consequential reactions. Tpot showed a correlation with disease-free survival in a univariate analysis but did not prove to be an independent factor. Moreover, the use of the minimum and corrected P-values did not identify a significant cut-off. Compared to conventional fractionation, accelerated hyperfractionation did not seem to offer a survival advantage in fast tumours though a better local control rate was noted. This limits the use of Tpot as a guide for selecting patients for accelerated hyperfractionation. For slowly growing tumours, tumour control and survival probabilities were not significantly different in the conventional fractionation and accelerated hyperfractionation groups. A rapid tumour growth was associated with a higher risk of distant metastases (P=0.01). In conclusion, tumour cell repopulation seems to be an important determinant of postoperative radiotherapy of locally advanced head and neck cancer despite lack of a definite association between Tpot and treatment outcome. In fast growing tumours accelerated hyperfractionation provided an improved local control but without a survival advantage. To gain a full benefit from treatment acceleration, the surgery-radiotherapy gap and the overall treatment time should not exceed 6 and 10 weeks respectively

Left atrial voltage, circulating biomarkers of fibrosis, and atrial fibrillation ablation. A prospective cohort study.

Aims To test the ability of four circulating biomarkers of fibrosis, and of low left atrial voltage, to predict recurrence of atrial fibrillation after catheter ablation. Background Circulating biomarkers potentially may be used to improve patient selection for atrial fibrillation ablation. Low voltage areas in the left atrium predict arrhythmia recurrence when mapped in sinus rhythm. This study tested type III procollagen N terminal peptide (PIIINP), galectin-3 (gal-3), fibroblast growth factor 23 (FGF-23), and type I collagen C terminal telopeptide (ICTP), and whether low voltage areas in the left atrium predicted atrial fibrillation recurrence, irrespective of the rhythm during mapping. Methods 92 atrial fibrillation ablation patients were studied. Biomarker levels in peripheral and intra-cardiac blood were measured with enzyme-linked immunosorbent assay. Low voltage (<0.5mV) was expressed as a proportion of the mapped left atrial surface area. Follow-up was one year. The primary endpoint was recurrence of arrhythmia. The secondary endpoint was a composite of recurrence despite two procedures, or after one procedure if no second procedure was undertaken. Results The biomarkers were not predictive of either endpoint. After multivariate Cox regression analysis, high proportion of low voltage area in the left atrium was found to predict the primary endpoint in sinus rhythm mapping (hazard ratio 4.323, 95% confidence interval 1.337–13.982, p = 0.014) and atrial fibrillation mapping (hazard ratio 5.195, 95% confidence interval 1.032–26.141, p = 0.046). This effect was also apparent for the secondary endpoint. Conclusion The studied biomarkers do not predict arrhythmia recurrence after catheter ablation. Left atrial voltage is an independent predictor of recurrence, whether the left atrium is mapped in atrial fibrillation or sinus rhythm