Impact of lung density on isolated lung tumor dose in VMAT using inline MR-Linac

PurposeThis study investigated the impact of lung density on the isolated lung tumor dose for volumetric modulated arc therapy (VMAT) in an inline magnetic resonance linear accelerator (MR-Linac) using the Monte Carlo (MC) simulation.MethodsCT images of the thorax phantoms with lung tumors of 1, 2, and 3 cm diameters were converted into voxel-base phantoms with lung densities of 0.1, 0.2, and 0.3 g/cm³, respectively. The dose distributions were calculated for partial-arc VMAT. The dose distributions were compared using dose differences, dose volume histograms, and dose volume indices.ResultsIn all cases, the inline magnetic field significantly enhanced the lung tumor dose compared to that at 0 T. For the 1 cm lung tumor, the inline magnetic field of 1 T increased the minimum dose of 95% of the Planning target volume (PTV D₉₅) by 14.0% in 0.1 g/cm³ lung density as compared to that in 0.3 g/cm³ at 0 T. In contrast, at 0 and 0.5 T, the PTV D₉₅ in 0.3 g/cm³ lung density was larger than that in lung density of 0.1 g/cm³. For the 2 cm lung tumor, a similar tendency to 1 cm was observed, whereas the dose impact of lung density was smaller than that for 1 cm. For the 3 cm lung tumor, the lung tumor dose was independent of lung density at 0.5 T and 1.0 T.ConclusionThe inline MR-Linac with the magnetic field over 1 T can enhance the PTV D₉₅ for VMAT regardless of the lung density.     

Dendroclimatic potential of dendroanatomy in temperature-sensitive Pinus sylvestris

The most frequently and successfully used tree-ring parameters for the study of temperature variations are ring width and maximum latewood density (MXD). MXD is preferred over ring width due to a more prominent association with temperature. In this study we explore the dendroclimate potential of dendroanatomy based on the first truly well replicated dataset. Twenty-nine mature living Pinus sylvestris trees were sampled in North-eastern Finland at the cool and moist boreal forest zone, close to the latitudinal tree line, where ring width, X-ray MXD as well as the blue intensity counterpart MXBI were compared with dendroanatomical parameters. Maximum radial cell wall thickness as well as anatomical MXD and latewood density appeared to be the most promising parameters for temperature reconstruction. In fact, these parameters compare favorably to MXD derived from X-ray techniques as well as MXBI, in terms of shared variation and temperature correlations across frequencies and over time. The reasons for these results are thought to be the unprecedentedly high measurement resolution of the anatomical technique, which provide the optimal resolution – the cell – whereas X-ray techniques have a slightly lower resolution and BI techniques even lower. While the results of this study are encouraging, further tests on longer and multigenerational chronologies are required to more generally and fully assess the dendroclimate potential of anatomical parameters.     

Changes in soil properties and resistance to concentrated flow across a 25‐year passive restoration chronosequence of grasslands on the Chinese Loess Plateau

Revegetation represents an effective measure for preventing soil erosion on the Loess Plateau. However, the effects of revegetation‐induced changes in soil and root properties on soil resistance to concentrated flow erosion (SRC) remain unclear. This study sampled soils and roots across a 25‐year chronosequence from farmland to grasslands of different ages (3, 7, 10, 18, and 25 years) to quantify variations in soil and root properties (soil bulk density, SBD; soil disintegration rate, SDR; saturated hydraulic conductivity, SHC; organic matter content, OMC; water‐stable aggregate, WSA; mean weight diameter, MWD; root mass density, RMD; root length density, RLD; and root surface area density, RSAD) and their effects on SRC. Farmland and grassland SRCs were obtained using a hydraulic flume. Soil properties and root density gradually improved with restoration time. In terms of the comprehensive soil property index calculated via principal component analysis, grassland values were 0.66 to 1.94 times greater than farmland values. Grassland SRCs increased and gradually stabilized (>18 years) over time and were 1.60 to 8.26 times greater than farmland SRC. SRC improvement was significantly related to increases in OMC, SHC, WSA, and MWD and decreases in SBD and SDR over time. SRC was effectively simulated by the Hill curve of RMD, RLD, and RSAD. SDR, SHC, and RMD (0.5–1.0 mm) affected SRC the most. This study scientifically describes how revegetation improves soil quality and soil resistance to flow erosion, and suggests that vegetations rich in 0.5–1.0 mm roots should be preferred during revegetation.     

Wild gregarious settlements of Ostrea edulis in a semi‐enclosed sea lough: a case study for unassisted restoration

Ostrea edulis was once prolific throughout Europe and considered as the continent's native oyster. However, O. edulis currently exists in small fragmented assemblages where natural unaided recovery is rarely encountered. This research identified the small semi‐enclosed sea Lough of Strangford on the northeast coast of Northern Ireland as one of the few locations within Europe where the native oyster displayed gregarious natural rejuvenation. On close examination, four influential parameters appeared to assist in concentrated settlement; raised topographical cultch formations, shell coverage, the number of fecund in situ adults, and site protection. If these components were to be combined and managed as part of reintroduction and restoration initiatives, high‐density settlements and self‐sustaining populations may be possible. The research also identified that unregulated harvesting of intertidal O. edulis assemblages has the potential to seriously hinder natural recoveries. Indeed, the findings suggest that a review of policy in regards to intertidal hand gathering is necessary. However, naturally occurring high‐density settlements recorded during this research should be inspirational to all involved in the restoration of the native oyster.     

The protective effects of grape seed procyanidin B2 against asporin mediates glycated low‐density lipoprotein induced‐cardiomyocyte apoptosis and fibrosis

The progression of diabetic cardiomyopathy is related to cardiomyocyte dysfunction and apoptosis. Our previous studies showed that asporin (ASPN) was significantly increased in the myocardium of db/db mice through proteomics, and grape seed procyanidin B2 (GSPB2) significantly inhibited the expression of ASPN in the heart of db/db mice. We report here that ASPN played a critical role in glycated low‐density lipoproteins (gly‐LDL) induced‐cardiomyocyte apoptosis. We found that gly‐LDL upregulated ASPN expression. ASPN increased H9C2 cardiomyocyte apoptosis with down‐regulation of Bcl‐2, upregulation of transforming growth factor‐β1, Bax, collagen III, fibronectin, and phosphorylation of smad2 and smad3. However, GSPB2 treatment reversed ASPN‐induced impairments in H9C2 cardiomyocytes. These results provide evidence for the cardioprotective action of GSPB2 against ASPN injury, and thus suggest a new target for fighting against diabetic cardiomyopathy.     

The combined effect of host and food availability on optimized parasitoid life‐history traits based on a three‐dimensional trade‐off surface

The reproductive success of many insects is considered to be limited by two main factors: the availability of mature eggs to lay (termed egg limitation) and the time to locate suitable hosts (termed time limitation). High host density in the environment is likely to enhance oviposition opportunities, thereby selecting for higher investment in egg supply. In contrast, a shortage of food (e.g. sugar sources) is likely to increase the risk of time limitation, thereby selecting for higher allocation to initial energy reserves. To our knowledge, the combined effect of host and food availability on these optimal life‐history allocations has never been investigated. We thus modelled their simultaneous effects on a three‐dimensional trade‐off between initial investment in energy reserves, egg number and egg size, while focusing on insect parasitoids. The model was based on Monte Carlo simulations coupled with genetic algorithms, in order to identify the optimal life‐history traits of a single simulated parasitoid female in an environment in which both hosts and food are present in varying densities. Our results reproduced the simple predictions described above. However, some novel predictions were also obtained, especially when specific interactions between the different factors were examined and their effects on the three‐dimensional life‐history surface were considered. The work sheds light on long‐lasting debates regarding the relative importance of time versus egg limitation in determining insect life‐history traits and highlights the complexity of life‐history evolution, where several environmental factors act simultaneously on multiple traits.     

Development and validation of an experimental and theoretical method for the chiral discrimination of dinotefuran

Dinotefuran is a low-cost agrochemical considered a highly toxic product. In this sense, there is a need for its constant environmental, biological, and food control, aiming to ensure its use to humans as well as to preserve biodiversity and ecosystems. In the present work, we developed an experimental and theoretical method for dinotefuran chiral discrimination. According to the main results, the dinotefuran enantioselective separation was efficiently optimized by high-performance liquid chromatography evaluating the influence of different percentage compositions in the mobile phase to improve the resolution of the peaks in the chromatogram. The novelty of this work was the proposition of a reduced molecular model for the chiral selector amylose-Tris-(3,5-dimethylphenylcarbamate) polysaccharide that was able to adequately describe at the molecular level its interaction with the dinotefuran enantiomers. Besides, the thermodynamic and structural parameters obtained via density functional theory calculations pointed out the chiral discrimination as well as the enantiomeric elution order of the analyte studied, confirming the experimental data, thus validating our proposed method. Finally, hydrogen bonds and repulsive interactions played a key role in the discrimination between the diastereomeric complexes, and consequently, for the dinotefuran enantioselective separation.     

Using density surface models to estimate spatio-temporal changes in population densities and trend

Precise measures of population abundance and trend are needed for species conservation; these are most difficult to obtain for rare and rapidly changing populations. We compare uncertainty in densities estimated from spatio–temporal models with that from standard design-based methods. Spatio–temporal models allow us to target priority areas where, and at times when, a population may most benefit. Generalised additive models were fitted to a 31-year time series of point-transect surveys of an endangered Hawaiian forest bird, the Hawai‘i ‘ākepa Loxops coccineus. This allowed us to estimate bird densities over space and time. We used two methods to quantify uncertainty in density estimates from the spatio–temporal model: the delta method (which assumes independence between detection and distribution parameters) and a variance propagation method. With the delta method we observed a 52% decrease in the width of the design-based 95% confidence interval (CI), while we observed a 37% decrease in CI width when propagating the variance. We mapped bird densities as they changed across space and time, allowing managers to evaluate management actions. Integrating detection function modelling with spatio–temporal modelling exploits survey data more efficiently by producing finer-grained abundance estimates than are possible with design-based methods as well as producing more precise abundance estimates. Model-based approaches require switching from making assumptions about the survey design to assumptions about bird distribution. Such a switch warrants consideration. In this case the model-based approach benefits conservation planning through improved management efficiency and reduced costs by taking into account both spatial shifts and temporal changes in population abundance and distribution.     

气候变化和经济发展对肾综合征出血热发生的影响

肾综合征出血热(hemorrhagic fever with renal syndrome, HFRS)是一种啮齿动物传播的自然疫源性疾病, 危害严重, 已成为全球重要的公共卫生问题。本研究采用数理统计模型及小波分析方法, 对陕西省西安市鄠邑区1984-2016年HFRS的发生与鼠类、气候和经济因素的关系进行分析, 探讨气候和经济因素对HFRS发生的影响。小波分析结果表明, 该地区的HFRS暴发史可能分为两个时期, 推测每个时期具有不同的主要宿主, 在2002年褐家鼠(Rattus norvegicus)可能取代黑线姬鼠(Apodemus agrarius)成为HFRS疫源地的主要宿主。广义可加模型模拟结果表明, HFRS的发生与1984-2001年黑线姬鼠密度间存在极显著非线性效应(F_2.06,9.02 = 102.415, P < 0.01), 两者间显现为正相关; 与2002-2016年的褐家鼠密度间呈正相关(F_1.67,9.02 = 73.929, P < 0.01); HFRS主要宿主的这种变化可能与当地气候变化和经济发展有关: HFRS的发生与年平均温度存在极显著的非线性效应(F_2.93,9.02 = 12.164, P < 0.01), 两者间呈负相关; 同样, HFRS的发生与上一年的国内生产总值(GDP)也存在显著非线性效应(F_1.70,9.02 = 2.917, P < 0.05), 两者间也呈负相关。结构方程模型通过直接和间接的影响途径证明了这种转移机制, 发现温度对HFRS发生有显著的直接负向影响以及通过褐家鼠的间接正向影响; GDP对HFRS发生有直接的负向影响。本研究表明HFRS的发生与气候变化和经济发展相关, 两者均能影响HFRS的暴发, 该结论有助于今后更好地对HFRS疾病进行预防和控制。