Computational and experimental assessment of public dose from normal research reactor operations [abstract]

Abstract only availableThe Missouri University Research Reactor (MURR) in Columbia, Missouri is interested in the amount of the Argon-41 being produced and released to the environment. The objective of this work is to know what operations within the facility are contributing to this production and the quantities released. I'll be working in collaboration with Jeancarlo Torres (Computational Assessment) and Erick Scheerer (Experimental Assessment) in determining these parameters. The calculational work analyzes the distribution of releases from the stack at the MURR. The dose is then predicted with the Comply program. EPA's Comply model was developed based on the procedures in the National Council on Radiation Protection and Measurements Commentary No.3 (NCRP89). The Comply computer software may be used to demonstrate compliance with the National Emission Standards for Hazardous Air Pollutants (NESHAPS) in 40 CFR 61 Subpart I and H. Comply calculates the effective dose equivalent (EDE) from radionuclide released from stacks and vents. The Nuclear Activation Analysis (NAA) is used in the experimental assessment of Argon-41 production. Neutron Activation Analysis is a nuclear process used for determining concentrations of elements in a vast amount of materials. NAA allows discrete sampling of elements as it disregards chemical form of a sample and focuses solely on its nucleus. NAA is a sensitive analytical technique useful for performing both qualitative and quantitative multi-element analysis for mayor, minor and trace elements in samples from almost every conceivable field of scientific or technical interest. Using NAA we will irradiate air samples from around the facility to determine the concentration of natural Ar-40 to produce Ar-41 for measurement. The relationship between these two different projects is that the results of the experimental technique will indicate if excess argon is present in the facility and the computational technique will calculate the dose the activation of Ar-40 to Ar-41 may have on the environment

Effect of multimodal cues from a predatory fish on refuge use and foraging on an amphidromous shrimp

Background. Prey can alter their behavior when detecting predator cues. Little is known about which sensory channel, number of channels, or the interaction among channels that shrimp species use to evaluate the threat from predators. The amphidromous shrimp Xiphocaris elongata has an induced defense, an elongated rostrum, where predatory fishes are present. We sought to test if kairomones or visual cues when presented singly from fish either eating flakes or shrimp, had more effect on altering the temporal feeding and refuge use patterns of long-rostrum (LR) X. elongata. We were also interested in elucidating potential interactions among cues when presented simultaneously in different combinations (kairomones + visual + mechanosensory, kairomones + alarm + visual, kairomones + alarm, kairomones + visual) on the same response variables. We expected that when presented alone kairomones will significantly increase refuge use and decrease foraging, particularly late at night, in comparison to visual cues alone, and that multiple cues when presented simultaneously will further increase refuge use and decrease foraging at night. Methods. We exposed shrimp to individual or multiple cues from the predatory fish mountain mullet, Augonostomus monticola. We examined shrimp behavior with respect to refuge use and foraging activity during four time periods (after sunset, nighttime, sunrise, and sunset) in a 24-hour period. Results. Shrimp presented fish visual and chemical cues singly did not differ from one another but differed from control shrimp (no cues) with respect to refuge use or foraging. The number of shrimp using refuge in the treatment with most cues (KVM: Kairomones+ visual + mechanosensory) was higher than in all the treatments with less cues. A significant decline in foraging was observed when multiple cues were presented simultaneously. The highest number of shrimp foraged one hour after sunset and at nighttime. A significant interaction was observed between cue treatments and time periods, with shrimp in the KVM treatment foraging less and using more refuge late at night and at sunrise than shrimp in other treatments or time periods. Conclusions. The observation that fish chemical and visual cues when presented singly produced similar refuge use and foraging patterns was contrary to expectation and suggests that visual and chemical cues, when presented alone, provide redundant information to X. elongata with regards to predation threat. The significant increase in refuge use and reduction in foraging observed in the KVM treatment suggest multimodal signal enhancement in the perception of threat. This makes evolutionary sense in \u27\u27noisy\u27\u27 environments, such as streams, where detection, localization, and intention of predators is much improved when cues are received through multiple sensory channels

Environmental report actualization for the license renewal of the University of Missouri Research Reactor Center

Abstract only availableLicensing requirements for power as well as non-power reactors must address environmental concerns related to radioactive emissions. The purpose and need for the renewal of the operating license for the Missouri University Research Reactor (MURR) is to allow continued studies in nuclear related undergraduate and graduate level degree programs along with continued production of radioactive isotopes for cancer treatment and research for an additional 20 years beyond the current license of 40 years which expires on November 21, 2006. The MURR is a multi-disciplinary research and education facility that provides a wide range of analytical, radiographic, and irradiation services to the research community and the commercial sector. The licensing requirements are established by the U.S. Nuclear Regulatory Commission in 10 CFR § 51.45 Environmental Reports - General Requirements. As part of the license renewal process the environmental report which was created on 2001 needed to be updated and revised to assure of the quality of the information. To study the hypothetical dose received by the public from the radioactive emissions that are released by the MURR during normal operations, the Environmental Protection Agency (EPA) COMPLY program was utilized. This program is intended for use by NRC licensees and non-DOE federal facilities to determine if they meet the radiation dose standards imposed by EPA under the Clean Air Act. COMPLY was utilized using an average of the last 10 years of the stack effluent which was measured in Curies per year. The results obtained from the program indicated that the MURR is in compliance for the emission released to the atmosphere.NSF-REU/NIH Program in Radiochemistr

Micro-dwellings as housing for young adult professionals

Millennials 20-29 years old were disproportionately affected by the housing crisis resulting in 31% of them still living at home; shut out of the rental housing market (Johnson, 2010). They are cash-strapped due to mortgage inaccessibility and lack of affordable housing options. With aspirations to live in “exciting urban settings”, as studies suggest, many of them are amenable to living in smaller spaces presumed to be affordable, such as micro-dwellings. As different types of these surface in the housing market, this assumption remains untested, suggesting the need for further research. Therefore, this study explores micro-dwellings as a potential rental housing option for this population and addresses the following research question: What is the possible fit between the housing aspirations of young adults, and the micro-dwelling housing model? 1. What do young adults value most in housing? 2. Which, among the different micro-dwelling housing types available in the rental market, might be viable housing options for young adults? 3. What is the optimal design of micro-dwellings as housing for young adults? This exploratory study combines data-driven, qualitative, and empirical components for a mixed-methods approach. Observations of existing micro-dwellings were documented to assess their characteristics through site visits and a design charrette. Millennials’ housing aspirations were identified through literature review and examined via an online survey distributed to young adults in a mid-size city in the Southeast. Descriptive statistics analysis of the data found that: 1) Out of 32 responses recorded, 65.6% would prefer to live in an urban location; 2) 60.9% showed a high desire for proximity to neighborhood and community amenities, confirming previous published studies’ claims; 3) 40.7% would live in a micro-dwelling, suggesting that current models partially satisfy the needs of the population; 4) 53.1% would find micro-dwellings more desirable if they offered communal spaces to satisfy their socialization needs. The information gathered from the review of literature, site visits, design charrette, and survey informed a pattern language. This pattern consisted of twelve design guidelines which were then tested through an empirical component. To provide the necessary proof of concept and accept or reject the hypothesis that micro-dwellings are a viable housing option for young adults; a comprehensive design proposal was developed, composed of a micro-dwelling community model and its units

Reconstruction and Validation of a Genome-Scale Metabolic Model for the Filamentous Fungus Neurospora crassa Using FARM

The filamentous fungus Neurospora crassa played a central role in the development of twentieth-century genetics, biochemistry and molecular biology, and continues to serve as a model organism for eukaryotic biology. Here, we have reconstructed a genome-scale model of its metabolism. This model consists of 836 metabolic genes, 257 pathways, 6 cellular compartments, and is supported by extensive manual curation of 491 literature citations. To aid our reconstruction, we developed three optimization-based algorithms, which together comprise Fast Automated Reconstruction of Metabolism (FARM). These algorithms are: LInear MEtabolite Dilution Flux Balance Analysis (limed-FBA), which predicts flux while linearly accounting for metabolite dilution; One-step functional Pruning (OnePrune), which removes blocked reactions with a single compact linear program; and Consistent Reproduction Of growth/no-growth Phenotype (CROP), which reconciles differences between in silico and experimental gene essentiality faster than previous approaches. Against an independent test set of more than 300 essential/non-essential genes that were not used to train the model, the model displays 93% sensitivity and specificity. We also used the model to simulate the biochemical genetics experiments originally performed on Neurospora by comprehensively predicting nutrient rescue of essential genes and synthetic lethal interactions, and we provide detailed pathway-based mechanistic explanations of our predictions. Our model provides a reliable computational framework for the integration and interpretation of ongoing experimental efforts in Neurospora, and we anticipate that our methods will substantially reduce the manual effort required to develop high-quality genome-scale metabolic models for other organisms

Ant colonies: building complex organizations with minuscule brains and no leaders

Thus far the articles in the series JOD calls the “Organization Zoo” have employed the notion of a “zoo” metaphorically to describe an array of human institutions. Here we take the term literally to consider the design of the most complex organizations in the living world beside those of humans, a favorite of insect zoos around the world: ant colonies. We consider individuality and group identity in the functioning of ant organizations; advantages of a flat organization without hierarchies or leaders; self-organization; direct and indirect communication; job specialization; labor coordination; and the role of errors in innovation. The likely value and limitations of comparing ant and human organizations are briefly examined

Technical Pitfalls and Proposed Modifications of Instructions for Use for Endovascular Aortic Aneurysm Repair Using the Gore Excluder Conformable Device in Angulated and Short Landing Zones

We describe a case of an abdominal aortic aneurysm (AAA) and angulated proximal neck treated with a Gore Excluder conformable endoprosthesis and show relevant technical pitfalls in the deployment of the graft main body. An 82-year-old man presented with a 71-mm asymptomatic AAA with an angulated infrarenal proximal neck (75°) and was referred to our unit. The patient was treated with a 26-mm Gore Excluder conformable device, which was deployed slightly above the renal arteries after precatheterization of the lowest renal artery. The graft was then repositioned with support of the introducer sheath and a stiff guide wire. The proximal sealing zone was ballooned before the endograft delivery system was retrieved to avoid distal migration. Technical success was achieved. The patient was discharged with no complications. No type Ia endoleak was present on the 6-month computed tomography scan. Endovascular treatment of an AAA with a severe angulated proximal neck can be effective with a conformable stent graft if technical measures are used during deployment of the main body to optimize the seal

Technical Pitfalls and Proposed Modifications of Instructions for Use for Endovascular Aortic Aneurysm Repair Using the Gore Excluder Conformable Device in Angulated and Short Landing Zones

We describe a case of an abdominal aortic aneurysm (AAA) and angulated proximal neck treated with a Gore Excluder conformable endoprosthesis and show relevant technical pitfalls in the deployment of the graft main body. An 82-year-old man presented with a 71-mm asymptomatic AAA with an angulated infrarenal proximal neck (75°) and was referred to our unit. The patient was treated with a 26-mm Gore Excluder conformable device, which was deployed slightly above the renal arteries after precatheterization of the lowest renal artery. The graft was then repositioned with support of the introducer sheath and a stiff guide wire. The proximal sealing zone was ballooned before the endograft delivery system was retrieved to avoid distal migration. Technical success was achieved. The patient was discharged with no complications. No type Ia endoleak was present on the 6-month computed tomography scan. Endovascular treatment of an AAA with a severe angulated proximal neck can be effective with a conformable stent graft if technical measures are used during deployment of the main body to optimize the seal

Radiation Sensitivity in a Preclinical Mouse Model of Medulloblastoma Relies on the Function of the Intrinsic Apoptotic Pathway

While treatments that induce DNA damage are commonly used as anti-cancer therapies, the mechanisms through which DNA damage produces a therapeutic response are incompletely understood. Here we have tested whether medulloblastomas must be competent for apoptosis to be sensitive to radiation therapy. Whether apoptosis is required for radiation sensitivity has been controversial. Medulloblastoma, the most common malignant brain tumor in children, is a biologically heterogeneous set of tumors typically sensitive to radiation and chemotherapy; 80% of medulloblastoma patients survive long-term after treatment. We used functional genetic studies to determine if the intrinsic apoptotic pathway is required for radiation to produce a therapeutic response in mice with primary, Shh-driven medulloblastoma. We found that cranial radiation extended the survival of medulloblastoma-bearing mice and induced widespread apoptosis. Expression analysis and conditional deletion studies showed that p53 was the predominant transcriptional regulator activated by radiation and was strictly required for treatment response. Deletion of Bax, which blocked apoptosis downstream of p53, was sufficient to render tumors radiation resistant. In apoptosis-incompetent, Bax-deleted tumors, radiation activated p53-dependent transcription without provoking cell death and caused two discrete populations to emerge. Most radiated tumor cells underwent terminal differentiation. Perivascular cells, however, quickly resumed proliferation despite p53 activation, behaved as stem cells, and rapidly drove recurrence. These data show that radiation must induce apoptosis in tumor stem cells to be effective. Mutations that disable the intrinsic apoptotic pathways are sufficient to impart radiation resistance. We suggest that medulloblastomas are typically sensitive to DNA-damaging therapies because they retain apoptosis competence