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

Gas-liquid mass transfer : a comparison of down-and up-pumping axial flow impellers with radial impellers

The performance of a down- and up-pumping pitched blade turbine and A315 for gas-liquid dispersion and mass transfer was evaluated and then compared with that of Rushton and Scaba turbines in a small laboratory scale vessel. The results show that when the axial flow impellers are operated in the up-pumping mode, the overall performance is largely improved compared with the down-pumping configuration. Compared with the radial turbines, the up-pumping A315 has a high gas handling capacity, equivalent to the Scaba turbine and is economically much more efficient in terms of mass transfer than both turbines. On the other hand, the uppumping pitched blade turbine is not as well adapted to such applications. Finally, the axial flow impellers in the down-pumping mode have the lowest performance of all the impellers studied, although the A315 is preferred of the pitched blade turbine

Biotrickling filtration of isopropanol under intermittent loading conditions

This paper investigates the removal of isopropanol by gas phase biotrickling filtration. Two plastic packing materials, one structured and one random, have been evaluated in terms of oxygen mass transfer and isopropanol removal efficiency (RE). Oxygen mass transfer experiments were performed at gas velocities of 104 and 312 m h-1 and liquid velocities between 3 and 33 m h-1. Both materials showed similar mass transfer coefficients up to liquid velocities of 15 m h-1. At greater liquid velocities, the structured packing exhibited greater oxygen mass transfer coefficients. Biotrickling filtration experiments were carried out at inlet loads (IL) from 20 to 65 g C m-3 h -1 and empty bed residence times (EBRT) from 15 14 to 160 s. To simulate typical industrial emissions, intermittent isopropanol loading (16 h/day, 5 16 day/week) and intermittent spraying frequency (15 min/1.5 hours) were applied. Maximum elimination capacity (EC) of 51 g C m-3 h -1 has been obtained for the random packing (IL of 65 g C m-3 h -1 17 , EBRT of 18 50 s). The decrease in irrigation frequency to 15 min every 3 hours caused a decrease in the outlet emissions from 86 to 59 mg C Nm-3 (inlet of 500 mg C Nm-3). The expansion of spraying to night and weekend periods promoted the degradation of the isopropanol accumulated in the water tank during the day, reaching effluent concentrations as low as 44 mg C Nm-3. After a 7 week starvation period, theperformance was recovered in less than 10 days, proving the robustness of the proces

Expectancy of success, subjective task-value, and message frame in the appraisal of value-promoting messages made prior to a high-stakes examination

© 2016 Springer Science+Business Media Dordrecht Previous research has examined how subjective task-value and expectancy of success influence the appraisal of value-promoting messages used by teachers prior to high-stakes examinations. The aim of this study was to examine whether message-frame (gain or loss-framed messages) also influences the appraisal of value-promoting messages. Two hundred and fifty-two participants in Years 12 and 13 read vignettes of fictional students who were high or low in subjective-task value, and expectancy of success, and asked to imagine how that student would appraise either a gain or loss-framed message. A challenge appraisal followed vignettes with high subjective task-value and high expectancy of success whereas a threat appraisal followed vignettes with high subjective task-value and low expectancy of success. A loss-framed message resulted in a stronger threat appraisal, and a gain-framed message in a greater disregarding appraisal for the vignette with high subjective task-value and high expectancy of success. Value-promoting messages can be appraised in different ways depending on combinations of intrapersonal (subjective task-value and expectancy of success) and interpersonal (message-frame) influences. © 2016 Springer Science+Business Media Dordrech

Enhanced gas-liquid mass transfer of an oscillatory constricted-tubular reactor

The mass transfer performance has been tested for gas-liquid flow in a new tubular reactor system, the oscillating mesotube (OMT), which features the oscillatory movement of fluid across a series of smooth constrictions located periodically along the vertical 4.4 mm internal diameter tube. The effect of the fluid oscillations (frequency,f, and center-to-peak amplitude, x(0), in the range of 0-20 s(-1) and 0-3 mm, respectively) on the overall volumetric mass transfer coefficient (k(L)a) has been tested by measuring the oxygen saturation levels with a fiber-optical microprobe (oxygen micro-optrode), and a mathematical model has been produced to describe the oxygen mass transport in the OMT. The oxygen mass transfer rates were about I order of magnitude higher (k(L)a values up to 0.16 s(-1)) than those values reported for gas-liquid contacting in a 50 mm internal diameter oscillatory flow reactor (OFR), for the same peak fluid oscillatory velocity, i.e., 2 pi fx(0). This represents remarkable oxygen transfer efficiencies, especially when considering the very low mean superficial gas velocity involved in this work (0.37 mm s(-1)). The narrower constrictions helped to increase the gas fraction (holdup) by reducing the rise velocity of the bubbles. However, the extent of radial mixing and the detachment of vortex rings from the surface of the periodic constrictions are actually the main causes of bubbles retention and effective gas-liquid contacting and are, thus, responsible for the enhancement of k(L)a in the OMT.N.R. thanks the Portuguese Foundation for Science and Technology (FCT) for financial support of his work (SFRH/BD/6954/2001)

Recommendations for improving public engagement with pre-incident information materials for initial response to a chemical, biological, radiological or nuclear (CBRN) incident: a systematic review

The risk of chemical, biological, radiological and nuclear (CBRN) incidents has increased in recent years, due to advances in technology, and increased willingness of terrorists to use unconventional weapons. There are basic actions which can reduce or prevent harm during such incidents. The speed with which these actions can be taken may be enhanced by providing pre-incident public information about how to undertake such actions. However, limited research has been carried out to identify potential benefits of providing pre-incident information in relation to preparing for and responding to terrorist attacks, including those involving CBRN agents. This paper presents findings from a systematic literature review which aimed to: examine potential efficacy of pre-incident information campaigns for improving public preparedness for CBRN incidents; identify what information should be included within public preparedness campaigns for CBRN incidents; and identify the best method(s) of providing pre-incident information for CBRN incidents. The review was carried out using Ovid, and selection and screening of papers followed a PRISMA framework. Findings showed that providing a pre-incident educational intervention generally resulted in an improvement in preparedness, compared to not providing any information. However, the majority of studies focused on improving preparedness behaviour in the immediate or short-term (<1 month). It is therefore unclear whether any improvement in preparedness is sustainable over the medium to longer-term. Further research is required to examine to what extent public information campaigns can improve public preparedness over the longer-term, and how best to enhance preparedness for CBRN incidents specifically

The Diabetes Pearl: Diabetes biobanking in The Netherlands

Contains fulltext : 109720.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND: Type 2 diabetes is associated with considerable comorbidity and severe complications, which reduce quality of life of the patients and require high levels of healthcare. The Diabetes Pearl is a large cohort of patients diagnosed with type 2 diabetes, covering different geographical areas in the Netherlands. The aim of the study is to create a research infrastructure that will allow the study of risk factors, including biomarkers and genetic determinants for severe diabetes complications. METHODS/DESIGN: Baseline examinations began November 2009 and will continue through 2012. By the end of 2012, it is expected that 7000 patients with type 2 diabetes will be included in the Diabetes Pearl cohort. To ensure quality of the data collected, standard operation procedures were developed and used in all 8 recruitment centers. From all patients who provide informed consent, the following information is collected: personal information, medication use, physical examination (antropometry, blood pressure, electrocardiography (ECG), retina photographs, ankle-brachial index, peripheral vibration perception), self-report questionnaire (socio-economic status, lifestyle, (family) history of disease, and psychosocial well-being), laboratory measurements (glucose, A1c, lipid profile, kidney function), biobank material (storage of urine and blood samples and isolated DNA). All gathered clinical data and biobank information is uploaded to a database for storage on a national level. Biobanks are maintained locally at all recruitment centers. DISCUSSION: The Diabetes Pearl is large-scale cohort of type 2 diabetes patients in the Netherlands aiming to study risk factors, including biomarkers and genetic markers, for disease deterioration and the development of severe diabetes complications. As a result of the well-designed research design and the national coverage, the Diabetes Pearl data can be of great value to national and international researchers with an interest in diabetes related research