Local Radiation Effects Research Articles

Wildfire aerosols and their impact on weather: A case study of the August 2021 fires in Greece using the WRF‐Chem model

AbstractWildfires are significant contributors to atmospheric gases and aerosols, impacting air quality and composition. This pollution from fires also affects radiative forcing, influencing short‐term weather patterns and climate dynamics. Our research employs the Weather Research and Forecasting model coupled with Chemistry (WRF‐Chem) to investigate the repercussions of wildfires on aerosol abundances and associated immediate weather responses. We examine the summer season of 2021, a period marked by severe wildfire events in the country during a heatwave period. We conducted sensitivity experiments including and excluding wildfire emissions to measure their effects on aerosol optical depth (AOD), radiative forcing, and weather features such as temperature, humidity, clouds, and atmospheric circulation. Our findings demonstrate that the radiative impacts of wildfires negatively influence the local temperature over the fire smoke plume‐affected areas. Conversely, neighbouring areas of continental Greece experience increases in temperature due to remote effects of wildfire emissions, caused by meteorological feedbacks that reduce atmospheric humidity. Crucially, including fire emissions significantly improves the simulated surface temperatures predicted by the model over the Greek domain. Our work demonstrates that wildfire‐generated aerosols can significantly impact weather conditions and highlights the importance of including both local radiative effects and remote feedback for achieving more accurate weather prediction.

Optimizing photovoltaic system configurations for domestic refrigerators in Miliana, Algeria: a simulation study

This study investigates the optimal configuration of a photovoltaic system to operate a home refrigerator with a power consumption of 130 watts. The research focuses on the city of Miliana, Algeria, analyzing the effects of local solar radiation and ambient temperature on battery charging dynamics throughout the year. Using MATLAB simulation techniques, we identified a 450 W solar panel coupled with a 150 Ah battery as the most efficient configuration to meet the power requirements of the refrigerator. Our findings highlight the fast charging capability of this PV system, achieving fast battery charging while maintaining a balance between energy production and consumption. However, we have also determined that increasing battery capacity beyond this limit results in longer charging times, shorter battery life cycles, and higher costs, which are counterproductive to the PV refrigerator-coupled system. The study emphasizes the importance of incorporating local climate conditions into the design of solar energy systems to ensure robust and sustainable energy solutions. The proposed configuration promises to reduce dependence on traditional energy sources, encourage the use of renewable energy in residential environments, and enhance environmental sustainability. Future research should evaluate these configurations in diverse geographic locations to validate and optimize the system for broader application, and explore advanced battery technologies to further improve efficiency and longevity.

A sensitivity study on radiative effects due to the parameterization of dust optical properties in models

Abstract. Most of the dust models underestimate the load of the large dust particles, consider spherical shapes instead of irregular ones, and have to deal with a wide range of the dust refractive index (RI) to be used. This leads to an incomplete assessment of the dust radiative effects and dust-related impacts on climate and weather. The current work aims to provide an assessment, through a sensitivity study, of the limitations of models to calculate the dust direct radiative effect (DRE) due to the underrepresentation of its size, RI, and shape. We show that the main limitations stem from the size and RI, while using a more realistic shape plays only a minor role, with our results agreeing with recent findings in the literature. At the top of the atmosphere (TOA) close to dust sources, the underestimation of size issues an underestimation of the direct warming effect of dust of ∼ 18–25 W m−2, for DOD = 1 (dust optical depth) at 0.5 µm, depending on the solar zenith angle (SZA) and RI. The underestimation of the dust size in models is less above the ocean than above dust sources, resulting in an underestimation of the direct cooling effect of dust above the ocean by up to 3 W m−2, for aerosol optical depth (AOD) of 1 at 0.5 µm. We also show that the RI of dust may change its DRE by 80 W m−2 above the dust sources and by 50 W m−2 at downwind oceanic areas for DOD = 1 at 0.5 µm at TOA. These results indicate the necessity of including more realistic sizes and RIs for dust particles in dust models, in order to derive better estimations of the dust DRE, especially near the dust sources and mostly for studies dealing with local radiation effects of dust aerosols.

The Global Patterns of Instantaneous CO2 Forcing at the Top of the Atmosphere and the Surface

Abstract The radiative forcing of carbon dioxide (CO2) at the top of the atmosphere (TOA) has a rich spatial structure and has implications for large-scale climate changes, such as poleward energy transport and tropical circulation change. Beyond the TOA, additional CO2 increases downwelling longwave at the surface, and this change in flux is the surface CO2 forcing. Here we thoroughly evaluate the spatiotemporal variation of the instantaneous, longwave CO2 radiative forcing at both the TOA and surface. The instantaneous forcing is calculated with a radiative transfer model using ERA5 reanalysis fields. Multivariate regression models show that the broadband forcing at the TOA and surface are well predicted by local temperatures, humidity, and cloud radiative effects. The difference between the TOA and surface forcing, the atmospheric forcing, can be either positive or negative and is mostly controlled by the column water vapor, with little explicit dependence on the surface temperature. The role of local variables on the TOA forcing is also assessed by partitioning the change in radiative flux to the component emitted by the surface versus that emitted by the atmosphere. In cold, dry regions, the surface and atmospheric contribution partially cancel out, leading to locally weak or even negative TOA forcing. In contrast, in the warm, moist regions, the surface and atmospheric components strengthen each other, resulting in overall larger TOA forcing. The relative contributions of surface and atmosphere to the TOA forcing depend on the optical thickness in the current climate, which in turn is controlled by the column water vapor.

Immune microenvironment remodeling after radiation of a progressing brain metastasis

Radiation is commonly used in the treatment of many cancers. However, its effects on anti-tumor immune responses are incompletely understood. Here, we present a detailed immunological analysis of two tumors from a patient with multiple non-small cell lung cancer metastases to the brain. One tumor was resected without treatment; the second was irradiated to a total dose of 30Gy and resected following further progression. Comprehensive single-cell analysis reveals a substantially reduced immune cell fraction in the irradiated tumor, including the depletion of tissue-resident macrophages and infiltration of pro-inflammatory monocytes. Despite the presence of similar somatic mutations in both tumors, radiation is associated with the depletion of exhausted, tumor-resident Tcell clones and their replacement by circulating clones unlikely to contribute to tumor-specific immunity. These results provide insight into the local effects of radiation on anti-tumor immunity and raise important considerations for the combination of radiation and immunotherapy.

Solar radiation explains litter degradation along alpine elevation gradients better than other climatic or edaphic parameters.

Organic matter (OM) decomposition has been shown to vary across ecosystems, suggesting that variation in local ecological conditions influences this process. A better understanding of the ecological factors driving OM decomposition rates will allow to better predict the effect of ecosystem changes on the carbon cycle. While temperature and humidity have been put forward as the main drivers of OM decomposition, the concomitant role of other ecosystem properties, such as soil physicochemical properties, and local microbial communities, remains to be investigated within large-scale ecological gradients. To address this gap, we measured the decomposition of a standardized OM source - green tea and rooibos tea - across 24 sites spread within a full factorial design including elevation and exposition, and across two distinct bioclimatic regions in the Swiss Alps. By analyzing OM decomposition via 19 climatic, edaphic or soil microbial activity-related variables, which strongly varied across sites, we identified solar radiation as the primary source of variation of both green and rooibos teabags decomposition rate. This study thus highlights that while most variables, such as temperature or humidity, as well as soil microbial activity, do impact decomposition process, in combination with the measured pedo-climatic niche, solar radiation, very likely by means of indirect effects, best captures variation in OM degradation. For instance, high solar radiation might favor photodegradation, in turn speeding up the decomposition activity of the local microbial communities. Future work should thus disentangle the synergistic effects of the unique local microbial community and solar radiation on OM decomposition across different habitats.

Experimental investigation on the heat transfer performance of ventilated floor with the influence of solar radiation

A heating system combing the solar air collector with the ventilated concrete floor (SAC-VCF) is proposed for application in residential buildings on Western Sichuan Plateau. For the integrated system, the solar energy is firstly absorbed by the solar air collector and stored inside the floor, then it is released at night to supply heat to the room. However, the intensive solar irradiation during the daytime, can cause the local overheating of floor surface and affect the heating performance of the VCF. In this paper, a test chamber is constructed to study the heating performance of the ventilated concrete floor with the effect of local solar radiation. Twenty-three cases with different ventilation rates and supply air temperatures have been performed with and without the solar radiation under steady-state conditions. With the effect of solar irradiation, the average surface temperature of floor is significantly affected with a maximum increase of 4.9 ℃. The local solar radiation weakens the heating supply of the ventilated air in the irradiated area, when increasing the solar radiation to 440 W/m2 the total heat transmitted to the floor through the ventilated air can be reduced by 46%. However, the total heating capacity of the VCF increases from 60.8 W/m2 to 99.0 W/m2, which is increased by 63%. Therefore, with the effect of the solar irradiation, the heating supply of the ventilated air is reduced while the total heating capacity of the VCF is increased, the solar radiation is one of heat sources of the VCF. Thus, the reasonable use of solar radiation can enhance the heat transfer performance of the VCF.

Effect of stimulator of interferon genes (STING) signaling on radiation-induced chemokine expression in human osteosarcoma cells.

Cancer cell-intrinsic mechanisms affecting radiation immunomodulation could be exploited to optimize systemic effects of localized radiation. Radiation-induced DNA damage is sensed by cyclic GMP-AMP synthase (cGAS), which ultimately activates stimulator of interferon (IFN) genes (STING). Resultant expression of soluble mediators such as CCL5 and CXCL10 can facilitate recruitment of dendritic cells and immune effector cells into the tumor. The primary objectives of this study were to determine the baseline expression levels of cGAS and STING in OSA cells and evaluate the dependence of OSA cells on STING signaling for eliciting radiation-induced expression of CCL5 and CXCL10. cGAS and STING expression, and CCL5/CXCL10 expression in control cells, STING-agonist treated cells, and cells treated with 5 Gy ionizing radiation were assessed utilizing RTqPCR, Western blot, and ELISA. U2OS and SAOS-2 OSA cells were deficient in STING relative to human osteoblasts (hObs), while SAOS-2-LM6 and MG63 OSA cells expressed equivalent amounts of STING compared to hObs. A dependence on baseline or induced STING expression was observed for STING-agonist, and radiation-induced, expression of CCL5 and CXCL10. This finding was confirmed by performing siRNA knockdown of STING in MG63 cells. These results show that STING signaling is necessary for radiation-induced expression of CCL5 and CXCL10 in OSA cells. Additional studies are necessary to determine whether STING expression in OSA cells in vivo alters immune cell infiltrates after radiation exposure. These data may also have implications for other potentially STING-dependent characteristics such as resistance to oncolytic virus cytotoxicity.

Evidence for Persistent Radiation-Related Injury to the Immune System in Patients With Local Breast Cancer

Severe and prolonged lymphopenia is well described in the literature as a consequence of local radiation and is associated with early death and impaired responses to immunotherapy. In animals, localized radiation results in histologic changes in lymph nodes that are distant from the radiation field. The sustained effects of radiation on distant lymph nodes in humans has not been previously described. This study was designed to assess changes in lymph nodes architecture outside the radiation field in women with breast cancer months after radiation treatment. Seven women were enrolled on a protocol to collect a distal abdominal lymph node during breast reconstruction with a deep inferior epigastric perforators (DIEP) flap. Five patients previously received chest wall irradiation on average 608 days prior to reconstruction while two patients did not receive radiation. The abdominal lymph node was compared to the initial (pre-radiation) mastectomy surgery lymph node by a blinded hematopathologist. The lymph node cellularity was graded by density score. The five patients who underwent radiation had striking reductions in their lymph node cellularity: average baseline score of 3 ± 1.2 with post lymph node density score of 1.2 ± 0.5, when compared to the two unirradiated patients: average baseline score of 4 with post lymph node density score of 3 ± 1.4. This small study suggests that localized radiation may have long-term impacts on distal lymph node basins in humans as has been seen in animals. Future studies evaluating prolonged systemic lymphopenia following radiation are needed to document the long-term systemic effects of local radiation, and the overall implications of this finding.

Frameless Cobalt60-Based Hypofractionated Stereotactic Radiosurgery (HSRS) for Brain Metastases: Impact of Dose and Volume

<h3>Purpose/Objective(s)</h3> Frameless, gated, image-guided, Cobalt⁶⁰-based hypofractionated stereotactic radiosurgery (Co⁶⁰-HSRS) is a novel technical paradigm in the treatment of brain metastases that allows for both the dosimetric benefits of the Co⁶⁰ based stereotactic radiosurgery (SRS) platform as well as the biologic benefits of fractionation. We report mature local control (LC) and adverse radiation effects (ARE) outcomes following 5 fraction Co⁶⁰-HSRS for intact brain metastases. <h3>Materials/Methods</h3> All patients with intact brain metastases treated with 5-fraction Co⁶⁰-HSRS between 2017-2020 were retrospectively reviewed. Patients were typically selected for HSRS as opposed to single fraction SRS if the metastases were larger (>2cm diameter), were in eloquent areas, or were in proximity to another lesion receiving HSRS. Survival estimates were determined per patient using Kaplan Meier methods, and LC as well as symptomatic ARE rates were determined per lesion using competing risk methods. Univariable competing risk regression using Fine and Gray's methods were performed, and subsequent multivariable (MVA) regression using a backwards step-wise selection technique generated the final adjusted models. <h3>Results</h3> In total 299 metastases in 146 patients were identified. The median clinical and radiologic follow-up was 10.6 (range 0.5-49.9) and 10.7 months (range 0.5-47.6), respectively. The median maximum tumor diameter and volume were 1.7 cm (range, 0.2-3.9 cm) and 2.38 cc (range, 0.004-24.92 cc), respectively. The median total dose and prescription isodose was 27.5 Gy (range, 20-27.5 Gy) in 5 daily fractions and 52% (range, 45%-93%), respectively. The median overall survival (OS) was 12.7 months and the 1-year LC rate was 85%. MVA identified a total dose of 27.5 Gy vs. ≤25 Gy (hazard ratio [HR] 0.59, p = 0.042), and prior chemotherapy exposure (HR 1.99, p = 0.015), as significant predictors of LC. The 1-year ARE rate was 10.8% and the symptomatic ARE rate was 1.8%. MVA identified a gross tumor volume of ≥4.5cc (HR 7.29, p < 0.001) and a mean intra-tumoral dose of ≥39 Gy (HR 3.17, p = 0.034) as significant predictors of symptomatic ARE. <h3>Conclusion</h3> Moderate total doses in 5 daily fractions of Co⁶⁰-HSRS were associated with high rates of LC and a low incidence of symptomatic ARE. A prescription dose of 27.5 Gy was superior with respect to local control versus ≤25 Gy in 5 daily fractions. Target volumes of 4.5cc or larger as well as mean dose >39 Gy, were associated with higher rates of symptomatic necrosis. Further study will help refine the optimal dosimetric constraints for Co⁶⁰-HSRS.

The effects of local stellar radiation and dust depletion on non-equilibrium interstellar chemistry

ABSTRACT Interstellar chemistry is important for galaxy formation, as it determines the rate at which gas can cool, and enables us to make predictions for observable spectroscopic lines from ions and molecules. We explore two central aspects of modelling the chemistry of the interstellar medium (ISM): (1) the effects of local stellar radiation, which ionizes and heats the gas, and (2) the depletion of metals on to dust grains, which reduces the abundance of metals in the gas phase. We run high-resolution (400 M⊙ per baryonic particle) simulations of isolated disc galaxies, from dwarfs to Milky Way-mass, using the fire galaxy formation models together with the chimes non-equilibrium chemistry and cooling module. In our fiducial model, we couple the chemistry to the stellar fluxes calculated from star particles using an approximate radiative transfer scheme; and we implement an empirical density-dependent prescription for metal depletion. For comparison, we also run simulations with a spatially uniform radiation field, and without metal depletion. Our fiducial model broadly reproduces observed trends in H i and H2 mass with stellar mass, and in line luminosity versus star formation rate for [C ii]$_{158 \rm {\mu m}}$, [O i]$_{63 \rm {\mu m}}$, [O iii]$_{88 \rm {\mu m}}$, [N ii]$_{122 \rm {\mu m}}$, and H α6563Å. Our simulations with a uniform radiation field predict fainter luminosities, by up to an order of magnitude for [O iii]$_{88 \rm {\mu m}}$ and H α6563Å, while ignoring metal depletion increases the luminosity of carbon and oxygen lines by a factor ≈ 2. However, the overall evolution of the galaxy is not strongly affected by local stellar fluxes or metal depletion, except in dwarf galaxies where the inclusion of local fluxes leads to weaker outflows and hence higher gas fractions.

Gamma knife icon based hypofractionated stereotactic radiosurgery (GKI-HSRS) for brain metastases: impact of dose and volume.

Gamma Knife Icon-based hypofractionated stereotactic radiosurgery (GKI-HSRS) is a novel technical paradigm in the treatment of brain metastases that allows for both the dosimetric benefits of the GKI stereotactic radiosurgery (SRS) platform as well as the biologic benefits of fractionation. We report mature local control and adverse radiation effect (ARE) outcomes following 5 fraction GKI-HSRS for intact brain metastases. Patients with intact brain metastases treated with 5-fraction GKI-HSRS were retrospectively reviewed. Survival, local control, and adverse radiation effect rates were determined. Univariable and multivariable regression (MVA) were performed on potential predictive factors. Two hundred and ninety-nine metastases in 146 patients were identified. The median clinical follow-up was 10.7months (range 0.5-47.6). The median total dose and prescription isodose was 27.5Gy (range, 20-27.5) in 5 daily fractions and 52% (range, 45-93), respectively. The median overall survival (OS) was 12.7months, and the 1-year local failure rate was 15.2%. MVA identified a total dose of 27.5Gy vs. ≤ 25Gy (hazard ratio [HR] 0.59, p = 0.042), and prior chemotherapy exposure (HR 1.99, p = 0.015), as significant predictors of LC. The 1-year ARE rate was 10.8% and the symptomatic ARE rate was 1.8%. MVA identified a gross tumor volume of ≥ 4.5cc (HR 7.29, p < 0.001) as a significant predictor of symptomatic ARE. Moderate total doses in 5 daily fractions of GKI-HSRS were associated with high rates of LC and a low incidence of symptomatic ARE.

Abstract 6279: Combination of metformin and local irradiation efficiently provokes abscopal effects in a murine rectal cancer model

Abstract Introduction; Neoadjuvant chemoradiation therapy (CRT) for locally advanced rectal cancer is effective for the reduction of local recurrence and improvement of postoperative QOL. However, CRT has little effects for metastatic lesions in distant organs and does not prolong the prognosis. Abscopal effect refers to a phenomenon of tumor regression at a distant tumor away from the irradiated primary tumor, presumably through the host immune system. Metformin, a widely used drug for the treatment of type 2 Diabetes Mellitus, has been shown to elicit anti-cancer effects partly through the activation of host immunity. However, how metformin modulates the abscopal effects of local radiation (RT) and metformin has not been well investigated. Method; Mice were subcutaneous inoculated by 1x106 cells of LuM1, a highly murine lung metastatic subclone of colon 26, at right flank of 7 weeks female BALB/c mice which were treated with metformin and/or RT. In RT groups, 4Gy X-ray was selectively given to subcutaneous tumors using lead shield under general anesthesia at day 13 and 15. Metformin hydrochloride (1mg/ml) were orally administrated from day13 continuously. At 28 days, mice were sacrificed, and we evaluated the weight of primary subcutaneous (s.c) tumor and the number of lung metastases. The phenotypes of splenocytes and blood were examined by flowcytometric analysis. Results: Local RT (4Gy x 2) suppressed the growth of s.c tumor to approximately half of control group although not statistically significantly (p=0.067). Metformin alone did not significantly suppress the tumor growth. However, when combined with RT, tumor weight at day28 was markedly reduced as compared with control group (p&amp;lt;0.01). Many lung metastases developed in all control group mice (Median (M)=120, 22-188) which was not changed by the treatment of metformin alone. The number of metastases tended to be reduced in RT group, although not significant (M=34, 3-78, p=0.12). In comparison, when metformin was combined to RT, the number of lung metastasis was markedly decreased (M=13, 0-70, p&amp;lt;0.01) with no metastases detected in 3 in 10 mice. The ratios of CD4(+) or CD8(+) T cells tended to be reduced in mice treated with RT alone, while increased in mice treated with RT and Metformin. CD49b(+)CD335(+) activated natural killer (NK) cells was significantly increase in combination group (1.1%±0.19% vs 2.6%±1.0%, p&amp;lt;0.05). The ratios PD-1(+) cells tended to be reduced, whereas those of IFN-γ (+) cells in T cell subpopulations after stimulation were significantly increased in mice treated with RT and metformin as compared with those in control group (CD4; 6.8±2.4% vs 10.4%±1.3%, p&amp;lt;0.05; CD8; 24.1±3.6% vs 40.4%±7.2%, p&amp;lt;0.01) Conclusion;Metformin restores T cell exhaustion and increase the number of activated NK cells in irradiated mice which may suppress the growth of lung metastases as abscopal effects. Citation Format: Mineyuki Tojo, Hideyo Miyato, Koji Koinuma, Hisanaga Horie, Hidenori Tsukui, Akira Saito, Yuki Kimura, Yuki Kaneko, Hideyuki Ohzawa, Hironori Yamaguchi, Alan Kawarai Lefor, Naohiro Sata, Joji Kitayama. Combination of metformin and local irradiation efficiently provokes abscopal effects in a murine rectal cancer model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6279.

Effective Radiative Forcings Due To Anthropogenic Emission Changes Under Covid-19 and Post-Pandemic Recovery Scenarios.

With the continuation of the Coronavirus Disease 2019 (Covid‐19) pandemic, the impacts of this catastrophe on anthropogenic emissions are no longer limited to its early stage. This study quantitatively estimates effective radiative forcings (ERFs) due to anthropogenic well‐mixed greenhouse gases (WMGHGs) and aerosols for the period 2020–2050 under the three latest Covid‐19 economic‐recovery scenarios using an aerosol‐climate model. The results indicate that reductions in both WMGHG and aerosol emissions under the Covid‐19 green recoveries lead to increases ranging from 0 to 0.3 W m−2 in global annual mean anthropogenic ERF over the period 2020–2050 relative to the Shared Socioeconomic Pathway 2‐4.5 scenario (the baseline case). These positive ERFs are mainly attributed to the rapid and dramatic decreases in atmospheric aerosol content that increase net shortwave radiative flux at the top of atmosphere via weakening the direct aerosol effect and low cloud cover. At the regional scale, reductions in aerosols contribute to positive ERFs throughout the Northern Hemisphere, while the decreased WMGHGs dominate negative ERFs over the areas away from aerosol pollution, such as the Southern Hemisphere oceans. This drives a strong interhemispheric contrast of ERFs. In contrast, the increased anthropogenic emissions under the fossil‐fueled recovery scenario lead to an increase of 0.3 W m−2 in global annual mean ERF in 2050 compared with the baseline case, primarily due to the contribution of WMGHG ERFs. The regional ERF changes are highly dependent on local cloud radiative effects.

Large‐diameter trees affect snow duration in post‐fire old‐growth forests

AbstractSnow duration in post‐fire forests is influenced by neighbourhoods of trees, snags, and deadwood. We used annually resolved, spatially explicit tree and tree mortality data collected in an old‐growth, mixed‐conifer forest in the Sierra Nevada, California, that burned at low to moderate severity to calculate 10 tree neighbourhood metrics for neighbourhoods up to 40 m from snow depth and snow disappearance sampling points. We developed two linear mixed models, predicting snow disappearance timing as a function of tree neighbourhood, litter density, and simulated incoming solar radiation, and two multiple regression models explaining variation in snow depth as a function of tree neighbourhood. Higher densities of post‐fire large‐diameter snags within 10 m of a sampling point were related to higher snow depth (indicating reduced snow interception). Higher densities of large‐diameter trees within 5 m and larger amounts of litter were associated with shorter snow duration (indicating increased longwave radiation emittance and accelerated snow albedo decay). However, live trees with diameters &gt;60 cm within 10 m of a snow disappearance sampling point were associated with a longer‐lasting spring snowpack. This suggests that, despite the local effects of canopy interception and emitted longwave radiation from boles of large trees, shading from their canopies may prolong snow duration over a larger area. Therefore, conservation of widely spaced, large‐diameter trees is important in old‐growth forests because they are resistant to fire and can enhance the seasonal duration of snowmelt.

The contribution of coral-reef-derived dimethyl sulfide to aerosol burden over the Great Barrier Reef: a modelling study

Abstract. Coral reefs have been found to produce the sulfur compound dimethyl sulfide (DMS), a climatically relevant aerosol precursor predominantly associated with phytoplankton. Until recently, the role of coral-reef-derived DMS within the climate system had not been quantified. A study preceding the present work found that DMS produced by corals had negligible long-term climatic forcing at the global–regional scale. However, at sub-daily timescales more typically associated with aerosol and cloud formation, the influence of coral-reef-derived DMS on local aerosol radiative effects remains unquantified. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) has been used in this work to study the role of coral-reef-derived DMS at sub-daily timescales for the first time. WRF-Chem was run to coincide with an October 2016 field campaign over the Great Barrier Reef, Queensland, Australia, against which the model was evaluated. After updating and scaling the DMS surface water climatology, the model reproduced DMS and sulfur concentrations well. The inclusion of coral-reef-derived DMS resulted in no significant change in sulfate aerosol mass or total aerosol number. Subsequently, no direct or indirect aerosol effects were detected. The results suggest that the co-location of the Great Barrier Reef with significant anthropogenic aerosol sources along the Queensland coast prevents coral-reef-derived aerosol from having a modulating influence on local aerosol burdens in the current climate.

RADI-04. Stereotactic radiosurgery in alveolar soft part sarcoma brain metastasis

BackgroundAlveolar soft part sarcoma (ASPS), although rare, has the highest incidence of brain metastasis amongst all sarcomas. Stereotactic radiosurgery (SRS) has been shown to be a well tolerated and effective treatment of intracranial sarcomatous metastasis. However, there is a paucity of published literature that guides radiation therapy in this condition.MethodsThis is a single centre retrospective review of all ASPS patients with intraparenchymal brain metastasis in our centre treated with stereotactic radiosurgery (SRS). SRS dosing is dichotomised into high and low dose (≥25 Gy and <25 Gy respectively) and outcomes such as local recurrence (LR) and radiation effects are noted. Successful treatment was defined as a lesion that regressed, is stable, or has less than 25% increase in tumour volume. Local recurrence (LR) was defined as increase in tumour volume by more than 25% during follow up.ResultsThere were three patients with 11 ASPS metastatic brain lesions, one of which underwent retreatment. Each lesion was followed up for a mean duration of 12 months (range: 5 – 22 months). Five lesions treated with a high dose regime and six lesions were given low dose. Lesions treated with high dose SRS experienced significantly less LR (20% vs 83.3%, OR 20.0 [95%CI 0.93 – 430), p = 0.036) with no increase in undue symptomatic radiation effects. Retreatment of lesions with LR after initial SRS using a low dose regime was successful, albeit only in the single recurrent lesion.ConclusionsWe conclude that SRS can be used as a first line treatment for ASPS brain metastasis that are not surgically accessible and that using a high dose for treatment is effective and safe. Multicentre collaborative studies can be performed to validate this claim.

Determining the stressed-strained state of concrete in the zone of exposure to local laser radiation

This paper reports the results of the physical and numerical experiments on determining the stressed-strained state of concrete in protective structures in the region of the effect of local point laser radiation. The software package LIRA10.8 (release 3.4) was used to build a computer model in the statement of a stationary thermal conductivity problem. To this end, the findings from the experimental studies were applied – the resulting temperature distribution and changes in the structure of concrete on the surface and deep into concrete cubes for more than 120 samples of concrete with three levels of moisture content: dried, natural humidity, and water-saturated. This paper gives the parameters of the simulation, the results of a numerical experiment, their analysis, and comparison with the results of a physical experiment. The temperature fields when establishing the dynamic temperature equilibrium, the level of stresses in concrete, derived from the physical experiments, correlate well with the results of the numerical experiment. The maximum temperature determined by the optical method at the surface of concrete was 1,350+50 °С. Deviations at control points do not exceed 12–70 °С in the temperature effect zone and 18–176 °С (1–11 %). At the rated radiation power of 30 W, the second stage of interaction was achieved; at 100 W – the fourth stage for concrete with a moisture content of 0–2.5 %; and, for water-saturated concrete, the fifth stage of interaction with the laser beam. A significant decrease in the thresholds between the stages of interaction between laser radiation and concrete was revealed, especially water-saturated concrete, compared to the thresholds for metals (the thresholds between the third and fifth stages were reduced by 103–104 times). The destruction of the walls of water-saturated pores in concrete occurred under the pressure of water vapor. The tangent stresses, in this case, were 1.7 MPa, and the values for the coefficient Kр, determined by the method of acoustic emission, were in the range of 4‒6. Such results explain the absence of normal microcracks due to the hoop effect. It was established that in the contact zone between a laser beam and concrete, about 90 % of the radiation energy dissipates, and in the adjacent heating zone ‒ up to 77 %. The optimal speed of beam movement when cleaning the concrete surface from organic, paint, and other types of contamination of 0.5–2 mm/s (surface temperature, 100–300 °С) has been proposed

A model for thermal protection ablative material with local thermal non-equilibrium and thermal radiation mechanisms

Novel resin-based ablative materials are manufactured for the Thermal Protection System (TPS) of hypersonic aircraft in recent years to adapt more extreme aerothermodynamic environment. The establishment of theoretical model and simulation method for accurately predicting material's responses can guide design of TPS and significantly reduce Research and Development (R&D) cycle and cost. In order to solve the problem of inaccurate material response calculated by the heritage models, which is caused by the new mechanisms involved in new materials. On the basis of heritage physical and chemical mechanisms for resin-based ablative materials, this study further introduces the mechanisms of the local thermal non-equilibrium and thermal radiation, and a developed thermal-fluid-ablation coupled theoretical model is established. The coupled model is numerically solved by writing computer codes. After completing the verification of the model and simulation codes, the influences of the new mechanisms on the performance of ablative material are analyzed. The results show that the effect of local thermal non-equilibrium and thermal radiation cannot be ignored for current ablative materials, in which the key factors are the pore size and porosity.

Manganese Porphyrin and Radiotherapy Improves Local Tumor Response and Overall Survival in Orthotopic Murine Mammary Carcinoma Models.

Novel synthetic compounds, known as manganese porphyrins (MnPs), have been designed to shift the redox status of both normal cells and cancer cells. When MnPs are coupled with cancer therapies, such as radiation, they have been shown to sensitize tumor cells to treatment and protect normal tissues from damage through the modulation of the redox status of various tissue types. Until now, our preclinical studies have focused on local effects of MnPs and radiation; however, we recognize that successful outcomes for cancer patients involve control of tumor cells throughout the body. In this study, using murine orthotopic mammary tumor models, we investigated how MnPs and radiation influence the development of distant metastasis. We hypothesized that the combination of MnP (MnP/RT), such as MnTnBuOE-2-PyP5+ and radiation treatment (RT) would increase local tumor control via a shift in the intratumoral redox environment, leading to subsequent downregulation of HIF-1 in the primary tumor. Secondarily, we hypothesized that these primary tumor treatment effects would result in a reduction in pulmonary metastatic burden. Balb/c mice with orthotopic 4T1 mammary carcinomas were treated with saline, MnP, RT or MnP/RT. We found MnP/RT did extend local tumor growth delay and overall survival compared to controls and was associated with increased intratumoral oxidative stress. However, the primary tumor growth delay observed with MnP/RT was not associated with a reduced pulmonary metastatic burden. Future directions to investigate the effects of MnP/RT on the development of distant metastasis may include modifications to the radiation dose, the experimental timeline or using a murine mammary carcinoma cell line with a less aggressive metastatic behavior. Clinical trials are underway to investigate the clinical utility of MnTnBuOE-2-PyP5+ for patients undergoing radiotherapy for various tumor types. The promising preclinical data from this study, as well as others, provides support that MnP/RT has the potential to improve local tumor control for these patients.