Model-based comparison of organ at risk protection between VMAT and robustly optimised IMPT plans

The comparison between intensity-modulated proton therapy (IMPT) and volume-modulated arc therapy (VMAT) plans, based on models of normal tissue complication probabilities (NTCP), can support the choice of radiation modality. IMPT irradiation plans for 50 patients with head and neck tumours originally treated with photon therapy have been robustly optimised against density and setup uncertainties. The dose distribution has been calculated with a Monte Carlo (MC) algorithm. The comparison of the plans was based on dose-volume parameters in organs at risk (OARs) and NTCP-calculations for xerostomia, sticky saliva, dysphagia and tube feeding using Langendijk's model-based approach. While the dose distribution in the target volumes is similar, the IMPT plans show better protection of OARs. Therefore, it is not the high dose confirmation that constitutes the advantage of protons, but it is the reduction of the mid-to-low dose levels compared to photons. This work investigates to what extent the advantages of proton radiation are beneficial for the patient's post-therapeutic quality of life (QoL). As a result, approximately one third of the patients examined benefit significantly from proton therapy with regard to possible late side effects. Clinical data is needed to confirm the model-based calculations

Household overcrowding and risk of SARS-CoV-2: analysis of the Virus Watch prospective community cohort study in England and Wales

Background: Household overcrowding is associated with increased risk of infectious diseases across contexts and countries. Limited data exist linking household overcrowding and risk of COVID-19. We used data collected from the Virus Watch cohort to examine the association between overcrowded households and SARS-CoV-2. // Methods: The Virus Watch study is a household community cohort of acute respiratory infections in England and Wales. We calculated overcrowding using the measure of persons per room for each household. We considered two primary outcomes: PCR-confirmed positive SARS-CoV-2 antigen tests and laboratory-confirmed SARS-CoV-2 antibodies. We used mixed-effects logistic regression models that accounted for household structure to estimate the association between household overcrowding and SARS-CoV-2 infection. // Results: 26,367 participants were included in our analyses. The proportion of participants with a positive SARS-CoV-2 PCR result was highest in the overcrowded group (9.0%; 99/1,100) and lowest in the under-occupied group (4.2%; 980/23,196). In a mixed-effects logistic regression model, we found strong evidence of an increased odds of a positive PCR SARS-CoV-2 antigen result (odds ratio 2.45; 95% CI:1.43–4.19; p-value=0.001) and increased odds of a positive SARS-CoV-2 antibody result in individuals living in overcrowded houses (3.32; 95% CI:1.54–7.15; p-value<0.001) compared with people living in under-occupied houses. // Conclusion: Public health interventions to prevent and stop the spread of SARS-CoV-2 should consider the risk of infection for people living in overcrowded households and pay greater attention to reducing household transmission

Digital museum objects and memory : postdigital materiality, aura and value

In the cultural sector we use digital museum objects every day; in exhibitions, websites, collections management systems, and on our social channels. But, what actually are these objects? Do we understand them as objects in their own right? With their own nature and essence?Publisher PDFPeer reviewe

Species History Masks the Effects of Human-Induced Range Loss – Unexpected Genetic Diversity in the Endangered Giant Mayfly Palingenia longicauda

Freshwater biodiversity has declined dramatically in Europe in recent decades. Because of massive habitat pollution and morphological degradation of water bodies, many once widespread species persist in small fractions of their original range. These range contractions are generally believed to be accompanied by loss of intraspecific genetic diversity, due to the reduction of effective population sizes and the extinction of regional genetic lineages. We aimed to assess the loss of genetic diversity and its significance for future potential reintroduction of the long-tailed mayfly Palingenia longicauda (Olivier), which experienced approximately 98% range loss during the past century. Analysis of 936 bp of mitochondrial DNA of 245 extant specimens across the current range revealed a surprisingly large number of haplotypes (87), and a high level of haplotype diversity (). In contrast, historic specimens (6) from the lost range (Rhine catchment) were not differentiated from the extant Rába population (, ), despite considerable geographic distance separating the two rivers. These observations can be explained by an overlap of the current with the historic (Pleistocene) refugia of the species. Most likely, the massive recent range loss mainly affected the range which was occupied by rapid post-glacial dispersal. We conclude that massive range losses do not necessarily coincide with genetic impoverishment and that a species' history must be considered when estimating loss of genetic diversity. The assessment of spatial genetic structures and prior phylogeographic information seems essential to conserve once widespread species

Location‐Routing with Conflicting Objectives: Coordinating eBeam Phytosanitary Treatment and Distribution of Mexican Import Commodities

We study a generalized location-routing problem in which the key decisions are made by supply chain partners with conflicting objectives. The context of our problem is the irradiation by electron beam (eBeam) of fresh produce imported from Mexico to reduce the threat of insects and pests to the U.S. agriculture. Because too few irradiation facilities exist to serve the current demand, we focus on two parties to be coordinated: the eBeam Services Provider, who will choose the facilities' locations and capacities, and the Distributor, who will determine routes for transporting fruits from Mexico to commercial hubs in the United States via these facilities. We demonstrate the value of cooperation and how that cooperation can be achieved and enforced for a supply chain that must coordinate the independent companies by the strategic decisions of facility location and capacity construction, as opposed to the more common coordination by capacity allocation or pricing. The parties' interactions are modeled as a sequential game with perfect information. Specifically, we formulate the sequential and cooperative decision-making problems as mixed-integer programs, analyze the computational complexity of the problems, and conduct extensive computational experiments. Additionally, we detail three schemes by which the parties can engage in profitable and enforceable cooperation. These methods progressively increase each party's commitment as trust is built and profits rise. Total cooperation increases overall profit by an average of 8.6%. Further, a stochastic program that uses sample average approximation is applied to demonstrate the results' robustness to nature's supply variations while maximizing the supply chain's overall profit.12 month embargo; published online: 10 February 2020This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]