432 research outputs found

    Climate Change: Anticipated Effects on High-Energy Laser Weapon Systems in Maritime Environments

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    anticipated effects on high energy laser weapon systems in maritime environments. Journal of Applied Meteorology and Climatology, American Meteorological Society, 50, 153-166This study quantifies the potential impacts on ship-defense high-energy-laser (HEL) performance due to atmospheric effects in the marine boundary layer driven by recent observations and analysis of worldwide sea surface temperatures (SSTs). The atmospheric effects are defined using the worldwide probabilistic climatic database available in the High Energy Laser End-to-End Operational Simulation (HELEEOS) model, which includes an SST database for the period 1854–1997. A more recent worldwide sea surface temperature database was provided by the Naval Postgraduate School for the period 1990-2008. Mean differences and trends between the two SST databases are used to deduce possible climate change impacts on simulated maritime HEL engagements. The anticipated effects on HEL propagation performance are assessed at an operating wave-length of 1.0642 um across the world's oceans and mapped to a 1 degree x 1 degree grid. The scenario evaluated is near surface and nearly horizontal over a range of 5000 m in which anticipated clear-air maritime aerosols occur. Summer and winter scenarios are considered. In addition to realistic vertical profiles of molecular and aerosol absorption and scattering, correlated optical turbulence profiles in probabilistic (percentile) format are used

    Becoming a teacher educator – the motivational factors

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    This study explores the factors that influenced the transition made by three participants from primary class teacher (or first-order practitioner) to Teacher Education (TE) lecturer (or second-order practitioner) in a Scottish Teacher Education Institution (TEI). The self-study case study methodology explored the factors that encouraged, and potentially inhibited, this career change. Data collection utilised auto-ethnographic narrative and findings were reviewed using a thematic analysis. Results are considered using a theoretical framework provided by Deci and Ryan’s Self-Determination Theory (SDT). The study identified three common, key themes leading to the participants career change: exploration and reinvention, key figures and lifelong learners. The findings suggest the participants were largely intrinsically motivated to make the career change. The results provide an insight for teachers considering this move and administrators within teacher education. The personal development implications for the participants are also considered

    Business experience and start-up size: buying more lottery tickets next time around?

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    This paper explores the determinants of start-up size by focusing on a cohort of 6247 businesses that started trading in 2004, using a unique dataset on customer records at Barclays Bank. Quantile regressions show that prior business experience is significantly related with start-up size, as are a number of other variables such as age, education and bank account activity. Quantile treatment effects (QTE) estimates show similar results, with the effect of business experience on (log) start-up size being roughly constant across the quantiles. Prior personal business experience leads to an increase in expected start-up size of about 50%. Instrumental variable QTE estimates are even higher, although there are concerns about the validity of the instrument

    Improved mineral prospectivity mapping using graph neural networks

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    Prospectivity analysis is an important part of the exploration information system (EIS) and mineral prospectivity mapping (MPM) is a widely used technique for prospectivity analysis. Despite MPM studies employing various machine learning (ML) algorithms for various purposes, MPM is still considered insufficient to capture the complexity of many important ore-forming geological processes. One potential issue concerns the difficulty with which conventional application of ML algorithms can learn from relational information. For instance, the conventional application of ML algorithms to tabular data for mineral exploration does not effectively consider spatial relations across or between geological terranes, because point data are treated as independent entities that do not influence their neighbor’s characteristics. Here, we demonstrate how re-designing exploration data into a graph format that focuses on spatial relationships can increase the effectiveness of mineral prospectivity mapping (MPM). We demonstrate that the use of graph deep learning can be beneficial when utilizing categorical and numerical exploration data. This approach was applied to three different commodities (copper, iron, and tin) in the southern United Kingdom in order to compare the effectiveness of the graph neural network (GNN) method with conventional ML techniques. We show that graph-based ML that utilizes immediate neighbor relationships in the training process significantly improves performance in three key metrics when compared to tabular data, particularly so when trained with a dataset where there are more barren (non-occurrence) data points than mineralized (occurrence) ones. To produce the most useful prospectivity maps, we recommend training a GNN algorithm by using an imbalanced training dataset comprising more barren data than mineralized data. We expect that further testing of the GNN method will lead to optimization of the supervised ML techniques used in MPM and EIS to prospect for key metal commodities in regions with incomplete geological data

    Can sacrificial feeding areas protect aquatic plants from herbivore grazing? Using behavioural ecology to inform wildlife management

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    Effective wildlife management is needed for conservation, economic and human well-being objectives. However, traditional population control methods are frequently ineffective, unpopular with stakeholders, may affect non-target species, and can be both expensive and impractical to implement. New methods which address these issues and offer effective wildlife management are required. We used an individual-based model to predict the efficacy of a sacrificial feeding area in preventing grazing damage by mute swans (Cygnus olor) to adjacent river vegetation of high conservation and economic value. The accuracy of model predictions was assessed by a comparison with observed field data, whilst prediction robustness was evaluated using a sensitivity analysis. We used repeated simulations to evaluate how the efficacy of the sacrificial feeding area was regulated by (i) food quantity, (ii) food quality, and (iii) the functional response of the forager. Our model gave accurate predictions of aquatic plant biomass, carrying capacity, swan mortality, swan foraging effort, and river use. Our model predicted that increased sacrificial feeding area food quantity and quality would prevent the depletion of aquatic plant biomass by swans. When the functional response for vegetation in the sacrificial feeding area was increased, the food quantity and quality in the sacrificial feeding area required to protect adjacent aquatic plants were reduced. Our study demonstrates how the insights of behavioural ecology can be used to inform wildlife management. The principles that underpin our model predictions are likely to be valid across a range of different resource-consumer interactions, emphasising the generality of our approach to the evaluation of strategies for resolving wildlife management problems

    Neoadjuvant cisplatin and fluorouracil versus epirubicin, cisplatin, and capecitabine followed by resection in patients with oesophageal adenocarcinoma (UK MRC OE05): an open-label, randomised phase 3 trial.

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    BACKGROUND: Neoadjuvant chemotherapy before surgery improves survival compared with surgery alone for patients with oesophageal cancer. The OE05 trial assessed whether increasing the duration and intensity of neoadjuvant chemotherapy further improved survival compared with the current standard regimen. METHODS: OE05 was an open-label, phase 3, randomised clinical trial. Patients with surgically resectable oesophageal adenocarcinoma classified as stage cT1N1, cT2N1, cT3N0/N1, or cT4N0/N1 were recruited from 72 UK hospitals. Eligibility criteria included WHO performance status 0 or 1, adequate respiratory, cardiac, and liver function, white blood cell count at least 3 × 10(9) cells per L, platelet count at least 100 × 10(9) platelets per L, and a glomerular filtration rate at least 60 mL/min. Participants were randomly allocated (1:1) using a computerised minimisation program with a random element and stratified by centre and tumour stage, to receive two cycles of cisplatin and fluorouracil (CF; two 3-weekly cycles of cisplatin [80 mg/m(2) intravenously on day 1] and fluorouracil [1 g/m(2) per day intravenously on days 1-4]) or four cycles of epirubicin, cisplatin, and capecitabine (ECX; four 3-weekly cycles of epirubicin [50 mg/m(2)] and cisplatin [60 mg/m(2)] intravenously on day 1, and capecitabine [1250 mg/m(2)] daily throughout the four cycles) before surgery, stratified according to centre and clinical disease stage. Neither patients nor study staff were masked to treatment allocation. Two-phase oesophagectomy with two-field (abdomen and thorax) lymphadenectomy was done within 4-6 weeks of completion of chemotherapy. The primary outcome measure was overall survival, and primary and safety analyses were done in the intention-to-treat population. This trial is registered with the ISRCTN registry (number 01852072) and ClinicalTrials.gov (NCT00041262), and is completed. FINDINGS: Between Jan 13, 2005, and Oct 31, 2011, 897 patients were recruited and 451 were assigned to the CF group and 446 to the ECX group. By Nov 14, 2016, 327 (73%) of 451 patients in the CF group and 302 (68%) of 446 in the ECX group had died. Median survival was 23·4 months (95% CI 20·6-26·3) with CF and 26·1 months (22·5-29·7) with ECX (hazard ratio 0·90 (95% CI 0·77-1·05, p=0·19). No unexpected chemotherapy toxicity was seen, and neutropenia was the most commonly reported event (grade 3 or 4 neutropenia: 74 [17%] of 446 patients in the CF group vs 101 [23%] of 441 people in the ECX group). The proportions of patients with postoperative complications (224 [56%] of 398 people for whom data were available in the CF group and 233 [62%] of 374 in the ECX group; p=0·089) were similar between the two groups. One patient in the ECX group died of suspected treatment-related neutropenic sepsis. INTERPRETATION: Four cycles of neoadjuvant ECX compared with two cycles of CF did not increase survival, and cannot be considered standard of care. Our study involved a large number of centres and detailed protocol with comprehensive prospective assessment of health-related quality of life in a patient population confined to people with adenocarcinomas of the oesophagus and gastro-oesophageal junction (Siewert types 1 and 2). Alternative chemotherapy regimens and neoadjuvant chemoradiation are being investigated to improve outcomes for patients with oesophageal carcinoma. FUNDING: Cancer Research UK and Medical Research Council Clinical Trials Unit at University College London

    Human blood autoantibodies in the detection of colorectal cancer

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    Colorectal cancer (CRC) is the second most common malignancy in the western world. Early detection and diagnosis of all cancer types is vital to improved prognosis by enabling early treatment when tumours should be both resectable and curable. Sera from 3 different cohorts; 42 sera (21 CRC and 21 matched controls) from New York, USA, 200 sera from Pittsburgh, USA (100 CRC and 100 controls) and 20 sera from Dundee, UK (10 CRC and 10 controls) were tested against a panel of multiple tumour-associated antigens (TAAs) using an optimised multiplex microarray system. TAA specific IgG responses were interpo- lated against the internal IgG standard curve for each sample. Individual TAA specific responses were examined in each cohort to determine cutoffs for a robust initial scoring method to establish sensitivity and specificity. Sensitivity and specificity of combinations of TAAs provided good discrimination between cancer-positive and normal serum. The overall sensitivity and specificity of the sample sets tested against a panel of 32 TAAs were 61.1% and 80.9% respectively for 6 antigens; p53, AFP, K RAS, Annexin, RAF1 and NY-CO16. Furthermore, the observed sensitivity in Pittsburgh sample set in different clinical stages of CRC;stageI(n=19),stageII(n=40),stageIII(n=34)andstageIV(n=6)wassimilar (73.6%, 75.0%, 73.5% and 83.3%, respectively), with similar levels of sensitivity for right and left sided CRC. We identified an antigen panel of sufficient sensitivity and specificity for early detection of CRC, based upon serum profiling of autoantibody response using a robust multiplex antigen microarray technology. This opens the possibility of a blood test for screening and detection of early colorectal cancer. However this panel will require further validation studies before they can be proposed for clinical practice

    Structural controls on lithium mineralization in shear-zone hosted granitic pegmatites of the Zulu pegmatite field, Zimbabwe – implications for exploration

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    Funding: LK acknowledges funding from the SEG Hugh McKinstry fund and the Geological Society of London for fieldwork and analytical support. LK was supported by a National Environmental Research Council PhD studentship (Grant no. NE/S007474/1).Granitic pegmatites are a significant source of critical metals including tin, tantalum, and most notably lithium. To meet future demand, a comprehensive exploration model is required to assist in the discovery of new hard rock deposits. Whereas recent work has largely focused on understanding the source and mineralization processes of pegmatites, the structural controls on the distribution and size of individual deposits remains poorly understood and understudied. In this contribution, we present a structural study on the Zulu pegmatite field in Zimbabwe, which provides a good example of the influence of shear zones, host rock rheology, and lithological competency contrasts on the orientation, size, and distribution of pegmatite bodies within a pegmatite field. At Zulu, we observe both structural and petrographic evidence for two types of pegmatite emplacement within an active shear zone during D2 strike-slip dominated deformation. An early generation (Type 1) was emplaced syn-kinematic to D2 within dilational jogs subparallel to the shear fabric, and continued ductile shearing also drove significant recrystallization which affected the primary magmatic phases and therefore influenced the preserved mineralogy. A later generation (Type 2) was emplaced syn-to-late-kinematic to D2 along tension gashes and subordinate fracture sets oblique to the shear fabric, which served to truncate the cooling history and preserve a primarily magmatic mineralogy within this pegmatite group. By comparing Zulu to other large pegmatite deposits, we conclude that geologic structures are critical to source-to-sink connectivity in lithium pegmatite systems, and affect the mineralization potential of individual deposits by driving recrystallization. Assessing the structural history and relative timing of emplacement within a pegmatite field, in conjunction with detailed (micro)textural observations from within pegmatite bodies, is essential to understanding pegmatite emplacement geometries. A more systematic approach in constraining these relationships will therefore aid in generating new exploration targets in both greenfield and brownfield settings.Peer reviewe

    Designing an intervention to help people with colorectal adenomas reduce their intake of red and processed meat and increase their levels of physical activity: a qualitative study

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    Background: most cases of colorectal cancer (CRC) arise from adenomatous polyps and malignant potential is greatest in high risk adenomas. There is convincing observational evidence that red and processed meat increase the risk of CRC and that higher levels of physical activity reduce the risk. However, no definitive randomised trial has demonstrated the benefit of behaviour change on reducing polyp recurrence and no consistent advice is currently offered to minimise patient risk. This qualitative study aimed to assess patients' preferences for dietary and physical activity interventions and ensure their appropriate and acceptable delivery to inform a feasibility trial.Methods: patients aged 60-74 included in the National Health Service Bowel Cancer Screening Programme (NHSBCSP) were selected from a patient tracking database. After a positive faecal occult blood test (FOBt), all had been diagnosed with an intermediate or high risk adenoma (I/HRA) at colonoscopy between April 2008 and April 2010. Interested patients and their partners were invited to attend a focus group or interview in July 2010. A topic guide, informed by the objectives of the study, was used. A thematic analysis was conducted in which transcripts were examined to ensure that all occurrences of each theme had been accounted for and compared.Results: two main themes emerged from the focus groups: a) experiences of having polyps and b) changing behaviour. Participants had not associated polyp removal with colorectal cancer and most did not remember being given any information or advice relating to this at the time. Heterogeneity of existing diet and physical activity levels was noted. There was a lack of readiness to change behaviour in many people in the target population.Conclusion: this study has demonstrated the difficulties involved in developing interventions to change dietary and physical activity behaviour in this population. The need to tailor the intervention to individuals, the lack of knowledge about the aetiology of colon cancer and the lack of motivation to change behaviour are critical factors

    Elevated plasma levels of cardiac troponin-I predict left ventricular systolic dysfunction in patients with myotonic dystrophy type 1:A multicentre cohort follow-up study

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    Objective: High sensitivity plasma cardiac troponin-I (cTnI) is emerging as a strong predictor of cardiac events in a variety of settings. We have explored its utility in patients with myotonic dystrophy type 1 (DM1). Methods: 117 patients with DM1 were recruited from routine outpatient clinics across three health boards. A single measurement of cTnI was made using the ARCHITECT STAT Troponin I assay. Demographic, ECG, echocardiographic and other clinical data were obtained from electronic medical records. Follow up was for a mean of 23 months. Results: Fifty five females and 62 males (mean age 47.7 years) were included. Complete data were available for ECG in 107, echocardiography in 53. Muscle Impairment Rating Scale score was recorded for all patients. A highly significant excess (p = 0.0007) of DM1 patients presented with cTnI levels greater than the 99th centile of the range usually observed in the general population (9 patients; 7.6%). Three patients with elevated troponin were found to have left ventricular systolic dysfunction (LVSD), compared with four of those with normal range cTnI (33.3% versus 3.7%; p = 0.001). Sixty two patients had a cTnI level < 5ng/L, of whom only one had documented evidence of LVSD. Elevated cTnI was not predictive of severe conduction abnormalities on ECG, or presence of a cardiac device, nor did cTnI level correlate with muscle strength expressed by Muscle Impairment Rating Scale score. Conclusions: Plasma cTnI is highly elevated in some ambulatory patients with DM1 and shows promise as a tool to aid cardiac risk stratification, possibly by detecting myocardial involvement. Further studies with larger patient numbers are warranted to assess its utility in this setting
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