Prediction of Uranium Transport in an Aquifer at a Proposed Uranium In Situ Recovery Site: Geochemical Modeling as a Decision-Making Tool

Roll fronts are some of the most important uranium deposits and are quite common in the United States. Generally, a roll front has an oxidized zone and a reduced zone, the latter being the zone of high mineralization and a target for in situ recovery (ISR) mining. The challenge remains the gathering of information to enable making informed decisions regarding post-mining groundwater quality. In this study, potential uncertainties in uranium sorption on iron oxyhydroxides or hydrous ferric oxides (HFO) following mining were assessed, as these oxidized zones create a greater risk for future uranium transport than fully reduced zones. Using two different geochemical databases, uncertainties in predicting uranium sorption on HFO based on a post-recovery restoration scenario were studied. The scenario was assessed using one-dimensional PHREEQC geochemical modeling simulations with respect to: uranium, oxygen, carbon dioxide, and iron hydroxide concentrations. The results of the simulations showed that uranium concentrations in solution are likely to be controlled by the amount of HFO available for sorption and the concentration of uranium-carbonate complexes formed in the solution. The presence of calcium, through the dissolution of calcite, was found to reduce the adsorption of uranium onto HFO as the resulting uranium-calcium-carbonate complexes are quite soluble. Overall, the simulations provide a procedure for predicting down-gradient uranium concentrations based on ultimate restoration levels at uranium ISR sites. This is important for risk assessment, regulatory enforcement, and decision making

A graphical theory of competition on spatial resource gradients

Resource competition is a fundamental interaction in natural communities.However little is known about competition in spatial environments where organisms are able to regulate resource distributions. Here, we analyze the competition of two consumers for two resources in a one-dimensional habitat in which the resources are supplied from opposite sides. We show that the success of an invading species crucially depends on the slope of the resource gradients shaped by the resident. Our analysis reveals that parameter combinations which lead to coexistence in a uniform environment may favor alternative stable states in a spatial system, and vice versa. Furthermore, differences in growth rate, mortality or dispersal abilities allow a consumer to coexist stationarily with - or even outcompete - a competitor with lower resource requirements. Applying our theory to a phytoplankton model, we explain shifts in the community structure that are induced by environmental changes

An Overview of Solar Sail Propulsion within NASA

Solar Sail Propulsion (SSP) is a high-priority new technology within The National Aeronautics and Space Administration (NASA), and several potential future space missions have been identified that will require SSP. Small and mid-sized technology demonstration missions using solar sails have flown or will soon fly in space. Multiple mission concept studies have been performed to determine the system level SSP requirements for their implementation and, subsequently, to drive the content of relevant technology programs. The status of SSP technology and potential future mission implementation within the United States (US) will be described

Exploiting Randomness in Quantum Information Processing

We consider how randomness can be made to play a useful role in quantum information processing - in particular, for decoherence control and the implementation of quantum algorithms. For a two-level system in which the decoherence channel is non-dissipative, we show that decoherence suppression is possible if memory is present in the channel. Random switching between two potentially harmful noise sources can then provide a source of stochastic control. Such random switching can also be used in an advantageous way for the implementation of quantum algorithms.Comment: 10 pages, final versio

Building a Bicycle-Powered Centrifuge

Centrifuges are very common instruments utilized in research and clinical settings. The purpose of a centrifuge is to separate the components of a mixture using centrifugal force. An example of a process that utilizes centrifugation is the acquisition of a hematocrit, where red blood cells are separated from blood plasma and the other cellular components. Industrial centrifuges are expensive and generally employed in academic or clinical contexts. A bicycle centrifuge, on the contrary, may be designed and implemented in more generalized settings. Moreover, a bicycle centrifuge affords the opportunity to relate principles in physics to concepts specific to other scientific disciplines, such as biology and kinesiology

Advanced Diffractive MetaFilm Sailcraft

A fast-tracked multifaceted approach that integrated NASA, industry, and academia was successfully executed to advance the novel concept of radiation pressure by means of a thin diffractive film. This pioneering new approach to light sailing was found to offer advantages over reflective sails - especially for missions that include close orbits or a close fly-by of the sun.The research effort included experiments, numerical modeling, and an "incubator meeting" that brought together over 35 researchers and stakeholders to uncover some of the most feasible means of advancing both the TRL and mission capabilities of diffractive sailcraft. One of the outcomes of the incubator meeting was to focus this Phase I research on a solar polar orbiter mission for heliophysics experiments. NASA decadal surveys and other reports have repeatedly pointed out that scientists have only a paucity of information about the sun beyond the ecliptic plane. The TRL has been advanced from 1 to 3 during this Phase I research with the help of experiments that have verified the predicted force and mechanical control afforded by diffractive sails. Knowledge gained from the experiments and numerical models was not only disseminated in peer reviewed publications and conferences, but it also resulted in a patent disclosure

Prospectus, June 12, 1972

GOVERNOR CITES PARKLAND STUDENT FOR COMMUNITY SERVICE; Harris Moeller Selected As New Dean of Students; Charles Gerron Is Student Senate President For 1972-73 School Year; Scholarships Awarded To Parkland Students; Parkland College Personnel Receive Recognition; Teacher Aides Hold Banquet; New Registration Procedures Will Begin In Fall \u2772 Quarter; Parkland Foundation Holds First Charter Meeting; Board of Trustees Have Two Very Eventful Meetings: Results of the Meeting of April 18, 1972, Results of the Meeting of May 16, 1972; Parkland Summer Session Begins June 19; New Non-Credit Courses Slated For Summer; Graebner to Speak at Parkland Commencement; Parkland Notices: Schedule changes, Vocational Information, Summer Jobs, Summer Graduate?, For Sale-Bargain!, Summer Registration, Lost; News From William J. Scott, Attorney General - State of Illinois; Parkland Student Government Passes Viet Nam Resolution; Journalism Club; A Day In The Park Has Large Turn-Out; The Editor\u27s View: Europe This Year - A-1; Student Senate Resolution; Seed For Thought; Unique Summer-Winter Program Developed In Maine; Youth Caucus \u2772 Organized In Illinois; Portfolios to Replace Grades; Coeds Bring Fraternity Ban, Other Campus News in Brief; New Academic Calendars; Entertainment & Fine Arts, Or ( We Got Culture Too! ); Movie Review: One Day In The Life Of Ivan Denisovich; Ear Wax; Orpheus Reborn: Been around the block twice..., greece looks good..., ast i..., A babe be born..., Sweet sweets..., Away To The Mountain; WLS - Wavelength; Book Review: The Assassins (Elia Kazan); Summer Session \u2772; Summer Session; Course Offerings; Angel & Clayborn in Nationals; Hart Beathttps://spark.parkland.edu/prospectus_1972/1007/thumbnail.jp

Computational complexity of the landscape I

We study the computational complexity of the physical problem of finding vacua of string theory which agree with data, such as the cosmological constant, and show that such problems are typically NP hard. In particular, we prove that in the Bousso-Polchinski model, the problem is NP complete. We discuss the issues this raises and the possibility that, even if we were to find compelling evidence that some vacuum of string theory describes our universe, we might never be able to find that vacuum explicitly. In a companion paper, we apply this point of view to the question of how early cosmology might select a vacuum.Comment: JHEP3 Latex, 53 pp, 2 .eps figure

Anti-androgens act jointly in suppressing spiggin concentrations in androgen-primed female three-spined sticklebacks - Prediction of combined effects by concentration addition

This is the post-print version of the final paper published in Aquatic Toxicology. 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 @ 2013 Elsevier B.V.Increasing attention is being directed at the role played by anti-androgenic chemicals in endocrine disruption of wildlife within the aquatic environment. The co-occurrence of multiple contaminants with anti-androgenic activity highlights a need for the predictive assessment of combined effects, but information about anti-androgen mixture effects on wildlife is lacking. This study evaluated the suitability of the androgenised female stickleback screen (AFSS), in which inhibition of androgen-induced spiggin production provides a quantitative assessment of anti-androgenic activity, for predicting the effect of a four component mixture of anti-androgens. The anti-androgenic activity of four known anti-androgens (vinclozolin, fenitrothion, flutamide, linuron) was evaluated from individual concentration-response data and used to design a mixture containing each chemical at equipotent concentrations. Across a 100-fold concentration range, a concentration addition approach was used to predict the response of fish to the mixture. Two studies were conducted independently at each of two laboratories. By using a novel method to adjust for differences between nominal and measured concentrations, good agreement was obtained between the actual outcome of the mixture exposure and the predicted outcome. This demonstrated for the first time that androgen receptor antagonists act in concert in an additive fashion in fish and that existing mixture methodology is effective in predicting the outcome, based on concentration-response data for individual chemicals. The sensitivity range of the AFSS assay lies within the range of anti-androgenicity reported in rivers across many locations internationally. The approach taken in our study lays the foundations for understanding how androgen receptor antagonists work together in fish and is essential in informing risk assessment methods for complex anti-androgenic mixtures in the aquatic environment.European Commission and Natural Environment Research Council