Clinical implications of the anisotropic analytical algorithm for IMRT treatment planning and verification

PURPOSE: To determine the implications of the use of the Anisotropic Analytical Algorithm(AAA) for the production and dosimetric verification of IMRT plans for treatments of the prostate, parotid, nasopharynx and lung. METHODS: 72 IMRT treatment plans produced using the Pencil Beam Convolution (PBC)algorithm were recalculated using the AAA and the dose distributions compared. 24 of the plans were delivered to inhomogeneous phantoms and verification measurements made using a pinpoint ionisation chamber. The agreement between the AAA and measurement was determined. RESULTS: Small differences were seen in the prostate plans, with the AAA predicting slightly lower minimum PTV doses. In the parotid plans, there were small increases in the lens and contralateral parotid doses while the nasopharyngeal plans revealed a reduction in the volume of the PTV covered by the 95% isodose (the V95%) when the AAA was used. Large changes were seen in the lung plans, the AAA predicting reductions in the minimum PTV dose and large reductions in the V95%. The AAA also predicted small increases in the mean dose to the normal lung and the V20. In the verification measurements, all AAA calculations were within 3% or 3.5mm distance to agreement of the measured doses. Conclusions: The AAA should be used in preference to the PBC algorithm for treatments involving low density tissue but this may necessitate re-evaluation of plan acceptability criteria. Improvements to the Multi-Resolution Dose Calculation algorithm used in the inverse planning are required to reduce the convergence error in the presence of lung tissue. There was excellent agreement between the AAA and verification measurements for all sites

Deriving Biomass Models for Small-Diameter Loblolly Pine on the Crossett Experimental Forest

Foresters and landowners have a growing interest in carbon sequestration and cellulosic biofuels in southern pine forests, and hence need to be able to accurately predict them. To this end, we derived a set of aboveground biomass models using data from 62 small-diameter loblolly pines (Pinus taeda) sampled on the Crossett Experimental Forest in southeastern Arkansas. Of the 25 equations initially evaluated, we chose 17 that best fit our dataset and compared them using a suite of conventional test statistics, including pseudo-R2 , root mean squared error (RMSE), and bias. Because most of the 17 models varied little in pseudoR 2 (ranging between 0.96 and 0.99), bias (all were within ± 0.01), and RMSE, an additional comparison was done using Akaike’s Information Criterion corrected for small sample size (AICc). This test statistic produced considerably more discrimination between the biomass models. Of the 17 models evaluated, six produced ΔAICc scores that met or exceeded the threshold for substantial support. To recommend a single preferred model, we then extrapolated beyond our actual data and qualitatively compared model predictions with those from the National Biomass Estimator. Our “best” model did not have the minimum AICc score, but rather predicted logically consistent aboveground biomass values at both the upper and lower ends of our extrapolation

Comparing Aboveground Biomass Predictions for an Uneven-Aged Pine-Dominated Stand Using Local, Regional, and National Models

Sequestration by Arkansas forests removes carbon dioxide from the atmosphere, storing this carbon in biomass that fills a number of critical ecological and socioeconomic functions. We need a better understanding of the contribution of forests to the carbon cycle, including the accurate quantification of tree biomass. Models have long been developed to predict aboveground live tree biomass, but few of these have been derived from Arkansas forests. Since there is geographic variability in the growth and yield of pine as a function of genetics, site conditions, growth rate, stand stocking, and other factors, we decided to compare aboveground tree biomass estimates for a naturally regenerated, uneven-aged loblolly pine (Pinus taeda)-dominated stand on the Crossett Experimental Forest (CEF) in southeastern Arkansas. These predictions were made using a new locally derived biomass equation, five regional biomass equations, and the pine model from the National Biomass Estimators. With the local model as the baseline, considerable biomass variation appeared across a range of diameters—at the greatest diameter considered, the minimum value was only 69% of the maximum. Using a recent inventory from the CEF’s Good Farm Forty to compare each model, stand-level biomass estimates ranged from a low of 76.9 Mg/ha (a different Arkansas model) to as much as 96.1 Mg/ha (an Alabama model); the local CEF equation predicted 82.5 Mg/ha. A number of different factors contributed to this variability, including differences in model form and derivation procedures, geographic origins, and utilization standards. Regardless of the source of the departures, their magnitude suggests that care be used when making large-scale biomass estimates

Bacterial Quality of Private Water Wells in Clark County, Arkansas

Most private water wells in Clark County appeared to be contaminated by bacteria, apparently entering the wells from surface water seepage. Eighteen to 24% of the wells investigated were positive for fecal contamination. Deeper wells were less often contaminated. More than one-half of the wells sampled exceeded recommended limits of inorganic chemicals for safe potable water. High concentrations of iron and manganese were most common, exceeding recommended limits in more than 40% of the well

Digital Intimacies and LGBT+ Youth: Celebration, Equity and Safety

“Digital Intimacies and LGBT+ youth” was commissioned by Brook, the wellbeing and sexual health charity for under-25s. It builds on the insights of its earlier report Digital Romance (McGeeney and Hanson 2017) which researched young people’s digital intimacy practices. For this report, we revisited survey and focus group data specifically from LGBT+ participants in that research. Additionally, we reviewed academic literature and gathered new data from LGBT+ youth groups, youth work practitioners and teachers, and parents / carers. Our research took place during the period of lockdowns due to Covid-19. These induced rapid shifts in perceptions of the online and in youth work practices, which have shaped our analysis here. The report summarises its findings under the headings of: // Celebration: We acknowledge the positive experiences that LGBT+ youth have online. We recognise LGBT+ youth as engaged creatively in diverse practices of community-building across many digital and offline spaces. Although there may be some (real and imagined) generational gaps in appreciating the value of digital cultures, we describe how youth work professionals rapidly and flexibly adapted their work with young people to online spaces under lockdown. Evidence that youth work practices were in turn able to positively impact some young people’s online relationship-building shows the value and vitality of cross-generational work and spaces. // Equity: We acknowledge the particular challenges faced by LGBT+ youth in a heteronormative world, which require specific resources to ameliorate. Some of these resources – especially for LGBT+ friendly youth services and other provision – are inadequate and / or under threat. Young people in our research looked particularly to schools to create safe and inclusive spaces including through relationships and sexuality education. We also draw attention to the responsibilities of platform providers, since many features of internet architecture prioritise commercial imperatives above privacy, preventing online harassment, or access to information. // Safety: We acknowledge the particular issues faced by LGBT+ youth in forging relationships and identities and their need for support. These intersect with many different aspects of identity. However we argue that an overemphasis on risk can be alienating and counterproductive, especially if it comes at the expense of more positive representations. Risk-taking is a necessary part of growing and learning. Managing risk should be seen as a lifelong project for all of us, constantly revisited, rather than something that can be avoided entirely or achieved at a single point in time. We conclude by offering a set of recommendations for practice relevant to funding bodies, campaigners, youth work professionals, schools, families and carers. These relate to: • Inclusive Relationships and Sex(uality) Education • Inclusive online safety • Resourcing anti-harassment strategies • Demanding more from digital media providers • Actively supporting parents and carers • Creating and networking safe spaces • Supporting youth community spaces • Supporting creativity/world-making • Outreach and exchang

Physical Activity Interventions for Older Adults in the Age of COVID-19 and Beyond

Topics in Exercise Science and Kinesiology Volume 2: Issue 1, Article 6, 2021. As the coronavirus (COVID-19) pandemic continues, it is important to understand why older adults are at higher risk for more severe morbidity and higher mortality compared to younger age groups. At the same time, there is a growing body of evidence suggesting physical activity and exercise can have positive benefits for older adults’ health. Point of application #1: The first step in keeping older adults active is motivating them to adhere to a structured program either at home, in a community setting, or in a long-term care facility. Point of application #2: There are many exercise programs that can be utilized to encourage older adults to stay active in order to improve their immune function and overall fitness. Point of application #3: Bingocize® is an example of an evidence-based program that has been successful during the pandemic in keeping participants motivated by being enjoyable, encouraging intergenerational connections and being feasible for older adults with a wide range of abilities

The 3-D LDV Measurements on a 30-Degree Swept Wing with a Simulated Ice Accretion

Three dimensional flowfield measurements have been obtained for a semispan 30-degree swept wing with a simulated glaze ice accretion. The model tested has a NACA 0012 section perpendicular to the leading edge. Measurements were made using a two-component laser Doppler velocimeter (LDV) system. Mean velocity measurements were obtained for all three velocity components. Streamwise turbulence intensities were also obtained. All measurements were taken in the University of Illinois 3 by 4 foot subsonic wind tunnel at a Reynolds number of 1 million and 8 degrees angle of attack. The data is presented in tabular form

Application of Simulated Reactivity Feedback in Nonnuclear Testing of a Direct-Drive Gas-Cooled Reactor

Nonnuclear testing can be a valuable tool in the development of an in-space nuclear power or propulsion system. In a nonnuclear test facility, electric heaters are used to simulate heat from nuclear fuel. Standard testing allows one to fully assess thermal, heat transfer, and stress related attributes of a given system but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. The integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and full nuclear testing. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response and response characteristics, and assess potential design improvements with a relatively small fiscal investment. Initial system dynamic response testing was demonstrated on the integrated SAFE 100a heat pipe cooled, electrically heated reactor and heat exchanger hardware. This Technical Memorandum discusses the status of the planned dynamic test methodology for implementation in the direct-drive gas-cooled reactor testing and assesses the additional instrumentation needed to implement high-fidelity dynamic testing

TB139: Stand Age and Density Effects on Volume and Specific Gravity of Black Spruce

Ten dominant or codominant trees were sampled from a 29-year-old black spruce stand, released at age 19, and ten of comparable dbh from a 77-year-old, unthinned stand. A variety of characteristics, including taper, volume, and specific gravity of the bole, as well as the change in specific gravity with age at breast height, were determined for trees from both stands. The older trees had significantly less taper, shorter crowns, approximately 1.9 times more merchantable volume and 10% higher specific gravity. The juvenile period for specific gravity was approximately 60 years. The higher specific gravity and merchantable volume of the older trees resulted in approximately 2.1 times more solid wood in the merchantable bole.https://digitalcommons.library.umaine.edu/aes_techbulletin/1197/thumbnail.jp

TB204: Organic Milk Production in Maine: Attributes, Costs, and Returns

This report summarizes attributes, costs, and returns for organic dairy farms in Maine that responded to the 2008 dairy cost of production survey. This survey and analysis was conducted by the University of Maine in cooperation with the Maine Milk Commission. This publication reports on data collected over the 2007 production year. Analysis and discussion of the data revolve around four categories. The first category averages all 30 organic farms to create a statewide group. The authors then broke these 30 farms into three size groups (small, medium, and large) based on the number of cows on each farm. There were nine small farms with an average of 30 cows on each farm, 10 medium farms with an average of 55 cows each, and 11 large farms with about an average of 100 cows each. The analysis presented here discusses characteristics of the three size groups, along with the statewide group.https://digitalcommons.library.umaine.edu/aes_techbulletin/1009/thumbnail.jp