Underwater optical wireless communications : depth dependent variations in attenuation

Depth variations in the attenuation coefficient for light in the ocean were calculated using a one-parameter model based on the chlorophyll-a concentration Cc and experimentally-determined Gaussian chlorophyll-depth profiles. The depth profiles were related to surface chlorophyll levels for the range 0–4  mg/m2, representing clear, open ocean. The depth where Cc became negligible was calculated to be shallower for places of high surface chlorophyll; 111.5 m for surface chlorophyll 0.8<Cc<2.2  mg/m3 compared with 415.5 m for surface Cc<0.04  mg/m3. Below this depth is the absolute minimum attenuation for underwater ocean communication links, calculated to be 0.0092  m−1 at a wavelength of 430 nm. By combining this with satellite surface-chlorophyll data, it is possible to quantify the attenuation between any two locations in the ocean, with applications for low-noise or secure underwater communications and vertical links from the ocean surface

Tillage and herbicide indices illustrate relationships among cropping systems

Non-Peer ReviewedFarming systems based on reduced inputs and increased diversity of crop types are of interest to producers as alternatives to conventional systems. Indices can be derived to estimate the impact of various farming practices on the system and its environment. The paper presents methods for calculating simple, weighted and modeled herbicide and tillage indices. The simple indices are based solely on farm input use records. The simple indices illustrated in the paper are number of herbicide applications and number of tillage operations. The weighted indices incorporate some knowledge about the operations using external data sources. The examples illustrated are herbicide active ingredient and cumulative disturbance. The third level of complexity is to model the impact of the operations on the environment using several external sources. The paper calculates environmental exposure to herbicides and residue removed. All indices are calculated for nine cropping systems included in the Scott Alternative Cropping System Study. Each index ranked the cropping systems differently. Number of herbicide applications underestimated the relative amount of active ingredient applied in the high input systems as compared to the reduced input (minimum tillage) systems. The types of herbicide necessary to control weeds in high input systems tended to result in higher environmental exposure to herbicides. The number of tillage passes also underestimated the relative amount of disturbance in the high input systems as compared to the organic systems. The amount of residue removed in the organic and high input systems was similar

Neurohumoral and ambulatory haemodynamic adaptations following isometric exercise training in unmedicated hypertensive patients

Objective: Hypertension remains the leading modifiable risk factor for cardiovascular disease (CVD). Isometric exercise training (IET) has been shown to be a useful non-pharmacological intervention for reducing resting blood pressure (BP). This study aimed to measure alterations in office BP, ambulatory BP, cardiac autonomic modulation and inflammatory and vascular biomarkers following a programme of IET in unmedicated hypertensive patients. Methods: Twenty-four unmedicated stage 1 hypertensive patients (age 43.8±7.3 years; height, 178.1±7 cm; weight 89.7±12.8 kg) were randomly assigned in a cross-over study design, to 4-weeks of home based IET and control period, separated by a 3-week washout period. Office and Ambulatory BP, cardiac autonomic modulation, and inflammatory and vascular biomarkers were recorded pre and post IET and control periods. Results: Clinic and 24-hour ambulatory BP significantly reduced following IET by 12.4/6.2 mmHg and 11.8/5.6 mmHg in systolic/diastolic BP, respectively (p<0.001 for both), compared to the control. The BP adaptations were associated with a significant (p=0.018) reduction in the average real variability of 24-hour ambulatory BP following IET, compared to control. Cardiac autonomic modulation improved by 11% (p<0.001), baroreceptor reflex sensitivity improved by 47% (p<0.001), and interleukin-6 and asymmetric dimethylarginine reduced by 10% (p=0.022) and 19% (p=0.023), respectively, which differed significantly to the control period. Conclusion: This is the first evidence of durable BP reduction and wider CVD risk benefits of IET in a relevant patient population. Our findings support the role of IET as a safe and viable therapeutic and preventative intervention in the treatment of HTN

Real world hospital costs following stress echocardiography in the UK: a costing study from the EVAREST/BSE-NSTEP multi-centre study

Background - Stress echocardiography is widely used to detect coronary artery disease, but little evidence on downstream hospital costs in real-world practice is available. We examined how stress echocardiography accuracy and downstream hospital costs vary across NHS hospitals and identified key factors that affect costs to help inform future clinical planning and guidelines. Methods - Data on 7636 patients recruited from 31 NHS hospitals within the UK between 2014 and 2020 as part of EVAREST/BSE-NSTEP clinical study, were used. Data included all diagnostic tests, procedures, and hospital admissions for 12 months after a stress echocardiogram and were costed using the NHS national unit costs. A decision tree was built to illustrate the clinical pathway and estimate average downstream hospital costs. Multi-level regression analysis was performed to identify variation in accuracy and costs at both patient, procedural, and hospital level. Linear regression and extrapolation were used to estimate annual hospital cost-savings associated with increasing predictive accuracy at hospital and national level. Results – Stress echocardiography accuracy varied with patient, hospital and operator characteristics. Hypertension, presence of wall motion abnormalities andhigher number of hospital cardiology outpatient attendances annually reduced accuracy, adjusted odds ratio of 0.78 (95% CI: 0.65 to 0.93), 0.27 (95% CI: 0.15 to 0.48), 0.99 (95% CI: 0.98 to 0.99) respectively, whereas a prior myocardial infarction, angiotensin receptor blocker medication, and greater operator experience increased accuracy, adjusted odds ratio of 1.77 (95% CI: 1.34 to 2.33), 1.64 (95% CI: 1.22 to 2.22), and 1.06 (95% CI: 1.02 to 1.09) respectively. Average downstream costs were £646 per patient (SD 1796) with significant variation across hospitals. The average downstream costs between the 31 hospitals varied from £384-1730 per patient. False positive and false negative tests were associated with average downstream costs of £1446 (SD £601) and £4192 (SD 3332) respectively, driven by increased non-elective hospital admissions, adjusted odds ratio 2.48 (95% CI: 1.08 to 5.66), 21.06 (95% CI: 10.41 to 42.59) respectively. We estimated that an increase in accuracy by 1 percentage point could save the NHS in the UK £3.2 million annually. Conclusion – This study provides real-world evidence of downstream costs associated with stress echocardiography practice in the UK and estimates how improvements in accuracy could impact healthcare expenditure in the NHS. A real-world downstream costing approach could be adopted more widely in evaluation of imaging tests and interventions to reflect actual value for money and support realistic planning

Creating a difference – a role for the arts in addressing child wellbeing in conflict-affected areas

Background Details findings from a project on the potential for arts activities and art therapy to support the mental health and wellbeing of children living in Kashmir. Methods The intervention engaged 30 school children over the course of one year who produced various forms of artwork and performances. In this paper, we report on project impacts, drawing on some of our qualitative measures including observations and interviews. Results Our research details impacts and improvements in areas of emotional expression, belonging, and agency. We also found an important role for schools to create safe, secure, and caring spaces to allow students to express themselves and work through traumatic feelings in a non-judgemental way. Conclusions School-based arts interventions can play an important role in the mental health and wellbeing of children. Critical here, however, are dedicated space, time, and resources to provide a supportive environment and to sustain activity in long-term

Global and regional left ventricular myocardial deformation measures by magnetic resonance feature tracking in healthy volunteers: comparison with tagging and relevance of gender

This work was funded by a grant from the Engineering and Physical Sciences Research Council (EP/G030693/1) and supported by the Oxford British Heart Foundation Centre of Research Excellence and the National Institute for Health Research Oxford Biomedical Research Centr

Influences on and patterns in total gaseous mercury (TGM) at Harwell, England

Total gaseous mercury (TGM) was monitored during 2013 at the rural monitoring site, Harwell, England using the Tekran 2537A monitoring system. Average TGM for the year was 1.45 ± 0.24 ng m−3. This is comparable to other northern hemisphere studies, but on average 0.5 ng m−3 higher than at its sister monitoring station at Auchencorth Moss, Scotland, but 14% lower than that found in a similar study at the same location of 1.68 ng m−3 in 1995/6. Using wind sector analysis we show the important influence of local emissions, with our data showing that the largest influence on TGM observed is that of the adjacent Science & Innovation campus, making the site more a ‘suburban background’. By using co-located measurements of black carbon and sulphur dioxide as tracers, we present an initial investigation into the impact of the closure of Didcot A coal fired power station, which ceased operating in March 2013. Further analysis using air mass back trajectories shows the long-range contribution to TGM from continental Europe, and that the lowest levels are associated with marine air masses from the west

Circuit Theory

Contains reports on three research projects.Lincoln Laboratory (Purchase Order DDL-B222)United States Department of the ArmyUnited States Department of the NavyUnited States Department of the Air Force (Contract AF19(604)-5200