THE MATROSHKA-III EXPERIMENT ONBOARD THE ISS - DEVELOPMENT STATUS

Radiation is currently seen as one of the main hazards for humans regarding long duration space missions especially mission planning beyond Low Earth Orbit (LEO). For the assessment of the radiation risk relevant radiation field models and tools can be applied. These all need and have to be benchmarked against real measured space data. The Matroshka-III (MTR-III) experiment as part of the Russian space experiment Matroshka-R Stage 5 (MTR-R) and realized within the framework of the Russian space research program will answer the questions about the distribution of dose within a human body and provide valuable input data for radiation transport calculations. The objective of the MTR-III experiment is to extend the measurements performed during the Matroshka (MTR) -1 and 2 experiments in a period of minimal solar activity to a complete solar cycle thereby covering also depth dose distributions during solar particle events. For this research the new MTR-III experiment uses an updated interface, improved software and new developed detector systems to allow the first time a continuous record of the doses in inner organ locations. Measurements will be performed in different ISS Modules (SM, MIM-1, MIM-2, MLM, NEM and others). The dose distribution inside the organ sites will be separately measured for the different sources of the radiation field (Trapped Radiation, Galactic Cosmic Rays and Solar Energetic Particles and neutrons) for selected locations inside the modules. The collected data serve to assess the risk of astronauts in dependence on geo- and heliophysical conditions and of various shielding configurations. They will also help to reduce the uncertainties in estimates of radiation risk and for the refinement of transport calculations through realistic shielding distributions that are needed for risk predictions in future missions. The presentation will give the current design status and detector development for the upcoming MTR-III mission

Depth Dose Distribution Study within a Phantom Torso after Irradiation with a Simulated Solar Particle Event at NSRL

The adequate knowledge of the radiation environment and the doses incurred during a space mission is essential for estimating an astronaut's health risk. The space radiation environment is complex and variable, and exposures inside the spacecraft and the astronaut's body are compounded by the interactions of the primary particles with the atoms of the structural materials and with the body itself Astronauts' radiation exposures are measured by means of personal dosimetry, but there remains substantial uncertainty associated with the computational extrapolation of skin dose to organ dose, which can lead to over- or underestimation of the health risk. Comparisons of models to data showed that the astronaut's Effective dose (E) can be predicted to within about a +10% accuracy using space radiation transport models for galactic cosmic rays (GCR) and trapped radiation behind shielding. However for solar particle event (SPE) with steep energy spectra and for extra-vehicular activities on the surface of the moon where only tissue shielding is present, transport models predict that there are large differences in model assumptions in projecting organ doses. Therefore experimental verification of SPE induced organ doses may be crucial for the design of lunar missions. In the research experiment "Depth dose distribution study within a phantom torso" at the NASA Space Radiation Laboratory (NSRL) at BNL, Brookhaven, USA the large 1972 SPE spectrum was simulated using seven different proton energies from 50 up to 450 MeV. A phantom torso constructed of natural bones and realistic distributions of human tissue equivalent materials, which is comparable to the torso of the MATROSHKA phantom currently on the ISS, was equipped with a comprehensive set of thermoluminescence detectors and human cells. The detectors are applied to assess the depth dose distribution and radiation transport codes (e.g. GEANT4) are used to assess the radiation field and interactions of the radiation field with the phantom torso. Lymphocyte cells are strategically embedded at selected locations at the skin and internal organs and are processed after irradiation to assess the effects of shielding on the yield of chromosome damage. The initial focus of the present experiment is to correlate biological results with physical dosimetry measurements in the phantom torso. Further on, the results of the passive dosimetry within the anthropomorphic phantoms represent the best tool to generate reliable data to benchmark computational radiation transport models in a radiation field of interest. The presentation will give first results of the physical dose distribution, the comparison with GEANT4 computer simulations based on a Voxel model of the phantom, and a comparison with the data from the chromosome aberration study

Bio-precipitation of uranium by two bacterial isolates recovered from extreme environments as estimated by potentiometric titration, TEM and X-ray absorption spectroscopic analyses

This is the post-print version of the final paper published in Journal of Hazardous Materials. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2011 Elsevier B.V.This work describes the mechanisms of uranium biomineralization at acidic conditions by Bacillus sphaericus JG-7B and Sphingomonas sp. S15-S1 both recovered from extreme environments. The U–bacterial interaction experiments were performed at low pH values (2.0–4.5) where the uranium aqueous speciation is dominated by highly mobile uranyl ions. X-ray absorption spectroscopy (XAS) showed that the cells of the studied strains precipitated uranium at pH 3.0 and 4.5 as a uranium phosphate mineral phase belonging to the meta-autunite group. Transmission electron microscopic (TEM) analyses showed strain-specific localization of the uranium precipitates. In the case of B. sphaericus JG-7B, the U(VI) precipitate was bound to the cell wall. Whereas for Sphingomonas sp. S15-S1, the U(VI) precipitates were observed both on the cell surface and intracellularly. The observed U(VI) biomineralization was associated with the activity of indigenous acid phosphatase detected at these pH values in the absence of an organic phosphate substrate. The biomineralization of uranium was not observed at pH 2.0, and U(VI) formed complexes with organophosphate ligands from the cells. This study increases the number of bacterial strains that have been demonstrated to precipitate uranium phosphates at acidic conditions via the activity of acid phosphatase

Experimental study of the role of physicochemical surface processing on the IN ability of mineral dust particles

During the measurement campaign FROST 2 (FReezing Of duST 2), the Leipzig Aerosol Cloud Interaction Simulator (LACIS) was used to investigate the influence of various surface modifications on the ice nucleating ability of Arizona Test Dust (ATD) particles in the immersion freezing mode. The dust particles were exposed to sulfuric acid vapor, to water vapor with and without the addition of ammonia gas, and heat using a thermodenuder operating at 250 °C. Size selected, quasi monodisperse particles with a mobility diameter of 300 nm were fed into LACIS and droplets grew on these particles such that each droplet contained a single particle. Temperature dependent frozen fractions of these droplets were determined in a temperature range between −40 °C ≤T≤−28 °C. The pure ATD particles nucleated ice over a broad temperature range with their freezing behavior being separated into two freezing branches characterized through different slopes in the frozen fraction vs. temperature curves. Coating the ATD particles with sulfuric acid resulted in the particles' IN potential significantly decreasing in the first freezing branch (T>−35 °C) and a slight increase in the second branch (T≤−35 °C). The addition of water vapor after the sulfuric acid coating caused the disappearance of the first freezing branch and a strong reduction of the IN ability in the second freezing branch. The presence of ammonia gas during water vapor exposure had a negligible effect on the particles' IN ability compared to the effect of water vapor. Heating in the thermodenuder led to a decreased IN ability of the sulfuric acid coated particles for both branches but the additional heat did not or only slightly change the IN ability of the pure ATD and the water vapor exposed sulfuric acid coated particles. In other words, the combination of both sulfuric acid and water vapor being present is a main cause for the ice active surface features of the ATD particles being destroyed. A possible explanation could be the chemical transformation of ice active metal silicates to metal sulfates. The strongly enhanced reaction between sulfuric acid and dust in the presence of water vapor and the resulting significant reductions in IN potential are of importance for atmospheric ice cloud formation. Our findings suggest that the IN concentration can decrease by up to one order of magnitude for the conditions investigated

Private Landowners’ Willingness to Enroll Their Properties in a Public Hunting Access Program in Northeast Missouri

State wildlife agencies have successfully used public hunting access fees to increase hunting opportunity and to provide a financial incentive to private landowners for maintaining habitat. Typical payments per hectare (ac) include $3.29 ($1.25) on average in Kansas, $2.47-$3.71($1-$1.50) for pheasant hunting in Colorado, $2.47-$12.36 ($1–$5) in North Dakota for pheasant hunting, and $4.45 ($1.80) on average in South Dakota. We studied the USDA Conservation Reserve Program (CRP) in 2004 in Adair, Knox, Macon, Monroe, Ralls, Randolph, Schuyler, and Scotland counties in northeast Missouri as part of a quail and songbird habitat restoration initiative. CRP is prominent in these counties with 83,040 ha (205,197 ac) enrolled. We conducted a mail-back survey of all CRP contract holders, totaling 3,283 landowners to study their willingness to enroll their properties in a hypothetical public- access hunting program. The survey was designed to provide information about landowner demographics, attitudes toward wildlife and hunting, and knowledge of wildlife habitat management aspects of the CRP. We used the Kansas Department of Wildlife and Parks Walk-In Hunting Access Program as an example for questions related to the concept of public-access hunting, and presented landowners with hypothetical annual lease payments for enrolling, using a discrete-choice modeling framework. Survey response rate was relatively high at 59.5%. The average respondent had 34.6 ha (85.5 ac) enrolled in CRP, and field size averaged 6.47 ha (16.0 ac), ranging from 0.04 to 84.9 ha (0.1–209.7 ac). Wildlife as a product of the CRP was ‘very’ or ‘somewhat important’ to 89% of respondents and, among a list of wildlife species and native plants, northern bobwhite (Colinus virginianus) was most popular with 80% of respondents checking ‘very’ or ‘somewhat important’ on the survey. The corresponding values were 53–66% for wild turkey (Meleagris gallopavo), deer, rabbit, pheasant, and songbirds. We asked if landowners would enroll any of their CRP land in a public-access hunting program (PAHP). We used 8 different versions of the survey, each with a different ‘offer’ level in the question to evaluate the potential costs of a PAHP program. The structure of the survey specified whether landowners would accept payment of $X/ac, where X was one value randomly selected from the set of$1, $2,$3, $4,$5, $7,$10, or $20. None of respondents chose ‘yes’ at a PAHP value of$0, 91.9% chose ‘no’, and 8.1% chose ‘don’t know’; respective values ($) and choices ($1-1.7%, 91.3%, and 6.9%; $2-3.0$3-4.0%, 84.9%, and 11.2%; $4-3.4$5- 4.7%, 83.4%, and 11.9%; $7-7.1$10-8.4%, 77.0%, and 14.7%; and $20-14.8$2/ac ($4.94/ha), ~ 3$10,500. About 1,012 ha (2,500 ac) would be designated for quail hunting of this hypothetical PAHP area, based on respondents’ answers to what type of hunting they would allow. We estimate that 5,261 ha (13,000 ac) would be enrolled with 2,489 ha (6,150 ac) open for quail hunting at an annual cost of about $90,000 if the payment level was raised to$7/ac ($17.30/ha). There is potential to improve the feasibility of CRP lands for bobwhite hunting in northeast Missouri by adding a public-access hunting incentive, but managers will be challenged to use this approach successfully. Landowners’ inclination to allow access for deer hunting, but not for quail hunting, reduces an agency’s justification for using quail hunting access as an approach to improve conservation of bobwhites, in addition to the relatively high cost

Grassland management effects on earthworm communities under ambient and future climatic conditions

Abstract The impacts of climate change on biodiversity can be modulated by other changing environmental conditions, e.g. induced by land-use change. The potential interactive effects of climate change and land use have rarely been studied for soil organisms. To test the effects of changing climatic conditions and land use on soil invertebrates, we examined earthworm communities across different seasons in different grassland-use types (intensively managed grassland, extensively managed meadow, and extensively managed sheep pasture).We predicted that the strength of climate change effects would vary with season and land use. Overall, extracted earthworm populations showed the strongest variations in response to the season, indicating major differences in activity patterns and extraction efficiency, while climate change and different grassland-use types had fewer and weaker effects. Future climate, characterized by slightly higher precipitation in spring and fall but a strong reduction during the summer, had positive effects on the abundance of extracted adult earthworms in spring but then reduced the abundance of active earthworms across the remaining seasons. In contrast, the total biomass of juveniles tended to be consistently lower under future climate conditions. Earthworm species responded differently to the climate change and different grassland management types, and these species-specific responses further varied strongly across seasons. Intensive grassland management had negative effects, due to plant community composition, while sheep grazing favoured earthworm populations, due to dung deposition. There were only limited interactive effects between climate and land use, which thus did not support our main hypothesis. Nevertheless, these results highlight the complex and context-dependent responses of earthworm communities and activity patterns to climate change, with potential consequences for long-term population dynamics and crucial ecosystem functions. This article is protected by copyright. All rights reserved.Peer reviewe