Performance of the eclipse monitor unit objective tool utilizing volumetric modulated arc therapy for rectal cancer

AimTo assess the performance of the monitor unit (MU) Objective tool in Eclipse treatment planning system (TPS) utilizing volumetric modulated arc therapy (VMAT) for rectal cancer.BackgroundEclipse VMAT planning module includes a tool to control the number of MUs delivered: the MU Objective tool. This tool could be utilized to reduce the total number of MUs in rectal cancer treatments.Materials and methods20 rectal cancer patients were retrospectively studied using VMAT and the MU Objective tool. The baseline plan for each patient was selected as the one with no usage of the MU Objective tool. The number of MUs of this plan was set to be the reference number of MUs (MU_ref). Five plans were re-optimized for each patient only varying the Max MU parameter. The selected values were 30%, 60%, 90%, 120% and 150% of MU_ref for each patient. Differences with respect to the baseline plan were evaluated regarding MU number and parameters for PTVs coverage evaluation, PTVs homogeneity and OARs doses assessment. A two-tailed, paired-samples t-test was used to quantify these differences.ResultsAverage relative differences in MU number obtained was 10% for Max MU values of 30% and 60% of MU_ref, respectively (p < 0.03). PTVs coverage and homogeneity were not compromised and discrepancies obtained with respect to baseline plans were not significant. Furthermore, maximum OARs doses deviations were also not significant.ConclusionsA 10% reduction in the MU number could be obtained without an alteration of PTV coverage and OARs doses for rectal cancer.     

Ensuring objectivity by applying the Mauri Model to assess the post-disaster affected environments of the 2011 MV Rena disaster in the Bay of Plenty,New Zealand

The 2011 MV Rena grounding on Otāiti (Astrolabe reef) in the Bay of Plenty, New Zealand is considered to be New Zealand’s worst maritime environmental disaster and one of the most expensive shipwreck and oil spill salvage and recovery operations ever undertaken, with the clean-up currently costing in excess of $660 million (NZD) (Schiel et al., 2016; Beca, 2014). The resultant environmental impacts due to the fuel oil spilled and flotsam were also experienced anthropocentrically as economic, social and cultural impacts. The presence and consideration of impacts experienced by the indigenous groups of the impacted regions within the on-going recovery process is a major contributing factor to the uniqueness of this scenario internationally. The scale and complexity of impacts from this disaster is without precedent in New Zealand. The consideration of past and potential future impacts is especially significant in present times, with the resource consent application to leave the remnants of the wreck and associated debris in place on the reef and seabed, being granted on February 26 2016.The assessment builds on the methodology presented by Faaui et al. (2016) which established indicator sets for measuring impacts upon the mauri of the affected environments (post-Rena state) and assessing the state of the environment prior to the grounding (pre-Rena state). Using the sustainability indicator sets compiled previously by Faaui et al. (2016), the Mauri Model Decision Making Framework has been used to present a holistic assessment of the impacts of the disaster on the reef and surrounding ecosystems, from October 2011 (date of the grounding) to October 2015. These indicators have been expanded on, defining the threshold conditions for scoring the indicators within the Mauri Model. The impact assessment methodology has included a process that identifies the indicator scoring thresholds which ensures objectivity in the scoring of indicators, and therefore the impact assessment, allowing for repeatable and robust results.This assessment is the first use of the Mauri Model Decision Making Framework at this scale, providing a holistic assessment of the impacts experienced within the Rena affected regions in this post-Rena time period. This research leads directly into the post resource consent time period and the associated future impacts as a result of the consent and given consent conditions.     

精神疲劳评价方法研究进展

长时间飞行活动所致的精神疲劳一直是航空航天医学中一个重要的课题。尤其随着我军航空技术的发展,精神疲劳已经成为影响飞行安全的重要原因之一。研究发现,精神疲劳发生时,机体的生理、心理、生化和工作绩效等功能会发生变化。例如,精神疲劳时,脑电图的theta波、delta波和alpha波发生变化、瞳孔直径增大、心率变异性的低频谱功率升高和高频谱功率降低、姿势控制能力下降、反应时延长、临界融合频率降低、血浆中氨基酸等功能性分子水平改变和认知能力的下降等。精神疲劳的客观评定方法就是研究者借助于某些设备来监测到这些变化,并根据这些变化对疲劳状态进行判断。本文将从生理、心理、生化和作业绩效等方面阐述了精神疲劳客观的评定方法,并指出了这些方法的优缺点。最后,本文对精神疲劳评价方法发展趋势做出了初步的判断,即我们应对精神疲劳进行综合量化评定,这样才能更全面准确地评估精神疲劳。     

聚类分析在制订育种方案中的应用

提出了品种选育中通过聚类分析划分品系的新思想。对全部目标性状做聚类分析,同类者放入同一品系中选育较好,不同类者可放入同一品系或不同品系。通过聚类分析可清楚地看出目标性状间的关系,为制订育种方案提供客观、清晰的理论依据。     

Constraints-based genome-scale metabolic simulation for systems metabolic engineering

Random mutagenesis and selection approaches used traditionally for the development of industrial strains have largely been complemented by metabolic engineering, which allows purposeful modification of metabolic and cellular characteristics by using recombinant DNA and other molecular biological techniques. As systems biology advances as a new paradigm of research thanks to the development of genome-scale computational tools and high-throughput experimental technologies including omics, systems metabolic engineering allowing modification of metabolic, regulatory and signaling networks of the cell at the systems-level is becoming possible. In silico genome-scale metabolic model and its simulation play increasingly important role in providing systematic strategies for metabolic engineering. The in silico genome-scale metabolic model is developed using genomic annotation, metabolic reactions, literature information, and experimental data. The advent of in silico genome-scale metabolic model brought about the development of various algorithms to simulate the metabolic status of the cell as a whole. In this paper, we review the algorithms developed for the system-wide simulation and perturbation of cellular metabolism, discuss the characteristics of these algorithms, and suggest future research direction.     

Subjectivity and flexibility in invasion terminology: too much of a good thing?

Invasions biologists have frequently debated whether the definition of invasive should include ecological and economic impacts. More recent criticisms posit that objective definitions are impossible in any absolute sense, while subjectivity is desirable for its flexibility and motivational qualities. We argue that such criticisms underestimate the extent of subjectivity already present in invasion biology. Ecological questions may be methodological if they relate directly to other ecological theories and models, or motivational if they focus on issues important to society as a whole. Motivational questions are important for engaging scientists, improving public understanding of science, and often have applied benefits. In contrast, methodological questions are constrained by established scientific theories, and are therefore more efficient for the development of scientific knowledge. Contrary to recent critiques, we suggest that greater objectivity is both achievable and desirable for the discipline of invasion biology and ecology generally.