Microbial Degradation of Cellulosic Material and Gas Generation: Implications for the Management of Low- and Intermediate-Level Radioactive Waste

Deep geologic repositories (DGR) in Canada are designed to contain and isolate low- and intermediate-level radioactive waste. Microbial degradation of the waste potentially produces methane, carbon dioxide and hydrogen gas. The generation of these gases increase rock cavity pressure and limit water ingress which delays the mobility of water soluble radionuclides. The objective of this study was to measure gas pressure and composition over 7 years in experiments containing cellulosic material with various starting conditions relevant to a DGR and to identify micro-organisms generating gas. For this purpose, we conducted experiments in glass bottles containing (1) wet cellulosic material, (2) wet cellulosic material with compost Maker, and (3) wet cellulosic material with compost Accelerator. Results demonstrated that compost accelerated the pressure build-up in the containers and that methane gas was produced in one experiment with compost and one experiment without compost because the pH remained neutral for the duration of the 464 days experiment. Methane was not formed in the other experiment because the pH became acidic. Once the pressure became similar in all containers after 464 days, we then monitored gas pressure and composition in glass bottle containing wet cellulosic material in (1) acidic conditions, (2) neutral conditions, and (3) with an enzyme that accelerated degradation of cellulose over 1965 days. In these experiments, acetogenic bacteria degraded cellulose and produced acetic acid, which acidity suppressed methane production. Microbial community analyses suggested a diverse community of archaea, bacteria and fungi actively degrading cellulose. DNA analyses also confirmed the presence of methanogens and acetogens in our experiments. This study suggests that methane gas will be generated in DGRs if pH remains neutral. However, our results showed that microbial degradation of cellulose not only generated gas, but also generated acidity. This finding is important as acids can limit bentonite swelling and potentially degrade cement and rock barriers, thus this requires consideration in the safety case as appropriate

Should we ignore U-235 series contribution to dose?

Environmental Risk Assessment (ERA) methodology for radioactive substances is an important regulatory tool for assessing the safety of licensed nuclear facilities for wildlife, and the environment as a whole. ERAs are therefore expected to be both fit for purpose and conservative. When uranium isotopes are assessed, there are many radioactive decay products which could be considered. However, risk assessors usually assume 235U and its daughters contribute negligibly to radiological dose. The validity of this assumption has not been tested: what might the 235U family contribution be and how does the estimate depend on the assumptions applied? In this paper we address this question by considering aquatic wildlife in Canadian lakes exposed to historic uranium mining practices. A full theoretical approach was used, in parallel to a more realistic assessment based on measurements of several elements of the U decay chains. The 235U family contribution varied between about 4% and 75% of the total dose rate depending on the assumptions of the equilibrium state of the decay chains. Hence, ignoring the 235U series will not result in conservative dose assessments for wildlife. These arguments provide a strong case for more in situ measurements of the important members of the 235U chain and for its consideration in dose assessments

Automation of Hubble Space Telescope Mission Operations

On June 13, 2011, after more than 21 years, 115 thousand orbits, and nearly 1 million exposures taken, the operation of the Hubble Space Telescope successfully transitioned from 24x7x365 staffing to 815 staffing. This required the automation of routine mission operations including telemetry and forward link acquisition, data dumping and solid-state recorder management, stored command loading, and health and safety monitoring of both the observatory and the HST Ground System. These changes were driven by budget reductions, and required ground system and onboard spacecraft enhancements across the entire operations spectrum, from planning and scheduling systems to payload flight software. Changes in personnel and staffing were required in order to adapt to the new roles and responsibilities required in the new automated operations era. This paper will provide a high level overview of the obstacles to automating nominal HST mission operations, both technical and cultural, and how those obstacles were overcome

Catch-Up Growth in Infants and Young Children With Faltering Growth:Expert Opinion to Guide General Clinicians

Faltering growth (FG) is a problem regularly seen by clinicians in infants and young children (&lt;2 years of age). It can occur due to non-disease-related and disease-related causes and is associated with a wide range of adverse outcomes, including shorter-term effects such as impaired immune responses and increased length of hospital stay, and longer-term consequences, including an impact on schooling and cognitive achievements, short stature, and socioeconomic outcomes. It is essential to detect FG, address underlying causes and support catch-up growth where this is indicated. However, anecdotal reports suggest misplaced fear of promoting accelerated (too rapid) growth may deter some clinicians from adequately addressing FG. An invited international group of experts in pediatric nutrition and growth reviewed the available evidence and guidelines on FG resulting from disease-related and non-disease-related effects on nutritional status in healthy term and small for gestational age infants and children up to the age of 2 years in low-, middle-, and high-income countries. Using a modified Delphi process, we developed practical consensus recommendations to provide clarity and practical recommendations for general clinicians on how FG should be defined in different young child populations at risk, how FG should be assessed and managed, and the role of catch-up growth after a period of FG. We also suggested areas where further research is needed to answer remaining questions on this important issue.</p

Catch-up Growth in Infants and Young Children with Faltering Growth: Expert Opinion to Guide General Clinicians

Faltering growth (FG) is a problem regularly seen by clinicians in infants and young children (<2 years of age). It can occur due to non-disease related and disease-related causes and is associated with a wide range of adverse outcomes, including shorter-term effects such as impaired immune responses and increased length of hospital stay, and longer-term consequences, including an impact on schooling and cognitive achievements, short stature, and socioeconomic outcomes. It is essential to detect FG, address underlying causes and support catch-up growth where this is indicated. However, anecdotal reports suggest misplaced fear of promoting accelerated (too rapid) growth may deter some clinicians from adequately addressing faltering growth. An invited international group of experts in paediatric nutrition and growth reviewed the available evidence and guidelines on FG resulting from disease-related and non-disease-related effects on nutritional status in healthy term and small for gestational age (SGA) infants and children up to the age of two years in low-, middle- and high-income countries. Using a modified Delphi process, we developed practical consensus recommendations to provide clarity and practical recommendations for general clinicians on how faltering growth should be defined in different young child populations at risk, how faltering growth should be assessed and managed and the role of catch-up growth after a period of faltering growth. We also suggested areas where further research is needed to answer remaining questions on this important issue

Ketamine kinetics in unmedicated and diazepam‐premedicated subjects

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109775/1/cptclpt1984235.pd

Experiencing food insecurity in childhood: influences on eating habits and body weight in young adulthood

Abstract Objective: To examine how food insecurity in childhood up to adolescence relates to eating habits and weight status in young adulthood. Design: A longitudinal study design was used to derive trajectories of household food insecurity from age 4.5 to 13 years. Multivariable linear and logistical regression analyses were performed to model associations between being at high risk of food insecurity from age 4.5 to 13 years and both dietary and weight outcomes at age 22 years. Setting: A birth cohort study conducted in the Province of Quebec, Canada. Participants: 698 young adults participating in the Québec Longitudinal Study of Child Development. Results: After adjusting for sex, maternal education and immigrant status, household income and type of family, being at high risk (compared to low risk) of food insecurity in childhood up to adolescence was associated with consuming higher quantities of sugar-sweetened beverages (ßadj: 0.64; 95% CI: 0.27-1.00), non-whole-grain cereal products (ßadj: 0.32; 95% CI: 0.07-0.56), and processed meat (ßadj: 0.14; 95% CI: 0.02-0.25), with skipping breakfast (ORadj: 1.97; 95% CI: 1.08-3.53), with eating meals prepared out of home (ORadj: 3.38; 95% CI: 1.52-9.02), with experiencing food insecurity (ORadj: 3.03; 95% CI: 1.91-4.76), and with being obese (ORadj: 2.01; 95% CI: 1.12-3.64), once reaching young adulthood. Conclusion: Growing up in families experiencing food insecurity may negatively influence eating habits and weight status later in life. Our findings reinforce the importance of public-health policies and programs tackling poverty and food insecurity, particularly for families with young children

Modelling the exposure of wildlife to radiation: key findings and activities of IAEA working groups

The International Atomic Energy Agency (IAEA) established the Biota Working Group (BWG) as part of its Environmental Modelling for Radiation Safety (EMRAS) programme in 2004 (http://www-ns.iaea.org/projects/emras/emras-biota-wg.htm). At that time both the IAEA and the International Commission on Radiological Protection (ICRP) were addressing environmental protection (i.e. protection of non-human biota or wildlife) within the on-going revisions to the Basic Safety Standards and Recommendations respectively. Furthermore, some countries (e.g. the USA, UK) were already conducting assessments in accordance with national guidelines. Consequently, a number of assessment frameworks/models had been or were being developed. The BWG was established recognising these developments and the need to improve Member State’s capabilities with respect to protection of the environment from ionizing radiation. The work of the BWG was continued within the IAEA’s EMRAS II programme by the Biota Modelling Group (http://wwwns. iaea.org/projects/emras/emras2/working-groups/working-group-four.asp)

Catch-Up Growth in Infants and Young Children With Faltering Growth: Expert Opinion to Guide General Clinicians.

Faltering growth (FG) is a problem regularly seen by clinicians in infants and young children (<2 years of age). It can occur due to non-disease-related and disease-related causes and is associated with a wide range of adverse outcomes, including shorter-term effects such as impaired immune responses and increased length of hospital stay, and longer-term consequences, including an impact on schooling and cognitive achievements, short stature, and socioeconomic outcomes. It is essential to detect FG, address underlying causes and support catch-up growth where this is indicated. However, anecdotal reports suggest misplaced fear of promoting accelerated (too rapid) growth may deter some clinicians from adequately addressing FG. An invited international group of experts in pediatric nutrition and growth reviewed the available evidence and guidelines on FG resulting from disease-related and non-disease-related effects on nutritional status in healthy term and small for gestational age infants and children up to the age of 2 years in low-, middle-, and high-income countries. Using a modified Delphi process, we developed practical consensus recommendations to provide clarity and practical recommendations for general clinicians on how FG should be defined in different young child populations at risk, how FG should be assessed and managed, and the role of catch-up growth after a period of FG. We also suggested areas where further research is needed to answer remaining questions on this important issue