134 research outputs found
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Summary of resources available to small water systems for meeting the 10 ppb arsenic drinking water limit.
With the lowering of the EPA maximum contaminant level of arsenic from 50 parts per billion (ppb) to 10 ppb, many public water systems in the country and in New Mexico in particular, are faced with making decisions about how to bring their system into compliance. This document provides detail on the options available to the water systems and the steps they need to take to achieve compliance with this regulation. Additionally, this document provides extensive resources and reference information for additional outreach support, financing options, vendors for treatment systems, and media pilot project results
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Lipid membranes on nanostructured silicon.
A unique composite nanoscale architecture that combines the self-organization and molecular dynamics of lipid membranes with a corrugated nanotextured silicon wafer was prepared and characterized with fluorescence microscopy and scanning probe microscopy. The goal of this project was to understand how such structures can be assembled for supported membrane research and how the interfacial interactions between the solid substrate and the soft, self-assembled material create unique physical and mechanical behavior through the confinement of phases in the membrane. The nanometer scale structure of the silicon wafer was produced through interference lithography followed by anisotropic wet etching. For the present study, a line pattern with 100 nm line widths, 200 nm depth and a pitch of 360 nm pitch was fabricated. Lipid membranes were successfully adsorbed on the structured silicon surface via membrane fusion techniques. The surface topology of the bilayer-Si structure was imaged using in situ tapping mode atomic force microscopy (AFM). The membrane was observed to drape over the silicon structure producing an undulated topology with amplitude of 40 nm that matched the 360 nm pitch of the silicon structure. Fluorescence recovery after photobleaching (FRAP) experiments found that on the microscale those same structures exhibit anisotropic lipid mobility that was coincident with the silicon substructure. The results showed that while the lipid membrane maintains much of its self-assembled structure in the composite architecture, the silicon substructure indeed influences the dynamics of the molecular motion within the membrane
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Investigating surety methodologies for cognitive systems.
Advances in cognitive science provide a foundation for new tools that promise to advance human capabilities with significant positive impacts. As with any new technology breakthrough, associated technical and non-technical risks are involved. Sandia has mitigated both technical and non-technical risks by applying advanced surety methodologies in such areas as nuclear weapons, nuclear reactor safety, nuclear materials transport, and energy systems. In order to apply surety to the development of cognitive systems, we must understand the concepts and principles that characterize the certainty of a system's operation as well as the risk areas of cognitive sciences. This SAND report documents a preliminary spectrum of risks involved with cognitive sciences, and identifies some surety methodologies that can be applied to potentially mitigate such risks. Some potential areas for further study are recommended. In particular, a recommendation is made to develop a cognitive systems epistemology framework for more detailed study of these risk areas and applications of surety methods and techniques
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Application of multidisciplinary analysis to gene expression.
Molecular analysis of cancer, at the genomic level, could lead to individualized patient diagnostics and treatments. The developments to follow will signal a significant paradigm shift in the clinical management of human cancer. Despite our initial hopes, however, it seems that simple analysis of microarray data cannot elucidate clinically significant gene functions and mechanisms. Extracting biological information from microarray data requires a complicated path involving multidisciplinary teams of biomedical researchers, computer scientists, mathematicians, statisticians, and computational linguists. The integration of the diverse outputs of each team is the limiting factor in the progress to discover candidate genes and pathways associated with the molecular biology of cancer. Specifically, one must deal with sets of significant genes identified by each method and extract whatever useful information may be found by comparing these different gene lists. Here we present our experience with such comparisons, and share methods developed in the analysis of an infant leukemia cohort studied on Affymetrix HG-U95A arrays. In particular, spatial gene clustering, hyper-dimensional projections, and computational linguistics were used to compare different gene lists. In spatial gene clustering, different gene lists are grouped together and visualized on a three-dimensional expression map, where genes with similar expressions are co-located. In another approach, projections from gene expression space onto a sphere clarify how groups of genes can jointly have more predictive power than groups of individually selected genes. Finally, online literature is automatically rearranged to present information about genes common to multiple groups, or to contrast the differences between the lists. The combination of these methods has improved our understanding of infant leukemia. While the complicated reality of the biology dashed our initial, optimistic hopes for simple answers from microarrays, we have made progress by combining very different analytic approaches
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Integration of biological ion channels onto optically addressable micro-fluidic electrode arrays for single molecule characterization.
The challenge of modeling the organization and function of biological membranes on a solid support has received considerable attention in recent years, primarily driven by potential applications in biosensor design. Affinity-based biosensors show great promise for extremely sensitive detection of BW agents and toxins. Receptor molecules have been successfully incorporated into phospholipid bilayers supported on sensing platforms. However, a collective body of data detailing a mechanistic understanding of membrane processes involved in receptor-substrate interactions and the competition between localized perturbations and delocalized responses resulting in reorganization of transmembrane protein structure, has yet to be produced. This report describes a systematic procedure to develop detailed correlation between (recognition-induced) protein restructuring and function of a ligand gated ion channel by combining single molecule fluorescence spectroscopy and single channel current recordings. This document is divided into three sections: (1) reported are the thermodynamics and diffusion properties of gramicidin using single molecule fluorescence imaging and (2) preliminary work on the 5HT{sub 3} serotonin receptor. Thirdly, we describe the design and fabrication of a miniaturized platform using the concepts of these two technologies (spectroscopic and single channel electrochemical techniques) for single molecule analysis, with a longer term goal of using the physical and electronic changes caused by a specific molecular recognition event as a transduction pathway in affinity based biosensors for biotoxin detection
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Studies of signaling domains in model and biological membranes through advanced imaging techniques: final report.
Cellular membranes have complex lipid and protein structures that are laterally organized for optimized molecular recognition and signal transduction processes. Knowledge of nanometer-scale lateral organization and its function is of great importance in the analysis of receptor-based signaling. In model membranes, we studied in detail the chemical and physical factors which result in lateral organization of lipids and lipid-mediated protein sequestration into signaling domains. In biological membranes, we mapped the location and follow the dynamic activity of specific membrane proteins involved in the immunological response of mast cells. These studies were enabled by our development of advanced imaging methods that provided both high spatial resolution and sensitivity to dynamical processes. Our technical approach was to combine the high sensitivity and time resolution of fluorescence imaging with the high lateral resolution of atomic force microscopy (AFM). Simultaneous fluorescence and AFM imaging allows correlation of the distribution and dynamic activity of specific biomolecules via fluorescence labeling with complete topographic information of the membrane. Overall, our unique imaging capabilities enabled us to examine membrane structure and function with much greater detail than was previously possible and thus provide a better understanding of cellular signaling
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On the need and use of models to explore the role of economic confidence:a survey.
Empirical studies suggest that consumption is more sensitive to current income than suggested under the permanent income hypothesis, which raises questions regarding expectations for future income, risk aversion, and the role of economic confidence measures. This report surveys a body of fundamental economic literature as well as burgeoning computational modeling methods to support efforts to better anticipate cascading economic responses to terrorist threats and attacks. This is a three part survey to support the incorporation of models of economic confidence into agent-based microeconomic simulations. We first review broad underlying economic principles related to this topic. We then review the economic principle of confidence and related empirical studies. Finally, we provide a brief survey of efforts and publications related to agent-based economic simulation
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A surety engineering framework to reduce cognitive systems risks.
Cognitive science research investigates the advancement of human cognition and neuroscience capabilities. Addressing risks associated with these advancements can counter potential program failures, legal and ethical issues, constraints to scientific research, and product vulnerabilities. Survey results, focus group discussions, cognitive science experts, and surety researchers concur technical risks exist that could impact cognitive science research in areas such as medicine, privacy, human enhancement, law and policy, military applications, and national security (SAND2006-6895). This SAND report documents a surety engineering framework and a process for identifying cognitive system technical, ethical, legal and societal risks and applying appropriate surety methods to reduce such risks. The framework consists of several models: Specification, Design, Evaluation, Risk, and Maturity. Two detailed case studies are included to illustrate the use of the process and framework. Several Appendices provide detailed information on existing cognitive system architectures; ethical, legal, and societal risk research; surety methods and technologies; and educing information research with a case study vignette. The process and framework provide a model for how cognitive systems research and full-scale product development can apply surety engineering to reduce perceived and actual risks
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