582 research outputs found
Hydrogeophysical Investigations at Hidden Dam, Raymond, California
Self-potential and direct current resistivity surveys are carried out at the Hidden Dam site in Raymond, California to assess present-day seepage patterns and better understand the hydrogeologic mechanisms that likely influence seepage. Numerical modeling is utilized in conjunction with the geophysical measurements to predict variably-saturated flow through typical two-dimensional dam cross-sections as a function of reservoir elevation. Several different flow scenarios are investigated based on the known hydrogeology, as well as information about typical subsurface structures gained from the resistivity survey. The flow models are also used to simulate the bulk electrical resistivity in the subsurface under varying saturation conditions, as well as the self-potential response using petrophysical relationships and electrokinetic coupling equations.
The self-potential survey consists of 512 measurements on the downstream area of the dam, and corroborates known seepage areas on the northwest side of the dam. Two direct current resistivity profiles, each approximately 2,500 ft (762 m) long, indicate a broad sediment channel under the northwest side of the dam, which may be a significant seepage pathway through the foundation. A focusing of seepage in low-topography areas downstream of the dam is confirmed from the numerical flow simulations, which is also consistent with past observations. Little evidence of seepage is identified from the self-potential data on the southeast side of the dam, also consistent with historical records, though one possible area of focused seepage is identified near the outlet works. Integration of the geophysical surveys, numerical modeling, and observation well data provides a framework for better understanding seepage at the site through a combined hydrogeophysical approach
Fabrication of 0.0075-Scale Orbiter Phosphor Thermography Test Models for Shuttle RTF Aeroheating Studies
This report details the techniques and fidelity associated with aeroheating models constructed in support of the return-to-flight boundary layer transition (BLT) activity for STS-114. This report provides technical descriptions of the methods, materials, and equipment used, as well as the surface quality results obtained with the cast ceramic phosphor thermography models
Unique opportunities for NMR methods in structural genomics
This Perspective, arising from a workshop held in July 2008 in Buffalo NY, provides an overview of the role NMR has played in the United States Protein Structure Initiative (PSI), and a vision of how NMR will contribute to the forthcoming PSI-Biology program. NMR has contributed in key ways to structure production by the PSI, and new methods have been developed which are impacting the broader protein NMR community
Unique opportunities for NMR methods in structural genomics
This Perspective, arising from a workshop held in July 2008 in Buffalo NY, provides an overview of the role NMR has played in the United States Protein Structure Initiative (PSI), and a vision of how NMR will contribute to the forthcoming PSI-Biology program. NMR has contributed in key ways to structure production by the PSI, and new methods have been developed which are impacting the broader protein NMR community
Antimicrobial Drug Resistance, Regulation, and Research1
Research models and regulatory measures could aid in developing antimicrobial drugs to address bacterial resistance
End-to-end communication test on variable length packet structures utilizing AOS testbed
This paper describes a communication test, which successfully demonstrated the transfer of losslessly compressed images in an end-to-end system. These compressed images were first formatted into variable length Consultative Committee for Space Data Systems (CCSDS) packets in the Advanced Orbiting System Testbed (AOST). The CCSDS data Structures were transferred from the AOST to the Radio Frequency Simulations Operations Center (RFSOC), via a fiber optic link, where data was then transmitted through the Tracking and Data Relay Satellite System (TDRSS). The received data acquired at the White Sands Complex (WSC) was transferred back to the AOST where the data was captured and decompressed back to the original images. This paper describes the compression algorithm, the AOST configuration, key flight components, data formats, and the communication link characteristics and test results
The efficacy of vigorous-intensity exercise as an aid to smoking cessation in adults with elevated anxiety sensitivity: study protocol for a randomized controlled trial
Background: Although cigarette smoking is a leading cause of death and disability in the United States (US), over 40 million adults in the US currently smoke. Quitting smoking is particularly difficult for smokers with certain types of psychological vulnerability. Researchers have frequently called attention to the relation between smoking and anxiety-related states and disorders, and evidence suggests that panic and related anxiety vulnerability factors, specifically anxiety sensitivity (AS or fear of somatic arousal), negatively impact cessation. Accordingly, there is merit to targeting AS among smokers to improve cessation outcome. Aerobic exercise has emerged as a promising aid for smoking cessation for this high-risk (for relapse) group because exercise can effectively reduce AS and other factors predicting smoking relapse (for example, withdrawal, depressed mood, anxiety), and it has shown initial efficacy for smoking cessation. The current manuscript presents the rationale, study design and procedures, and design considerations of the Smoking Termination Enhancement Project (STEP).
Methods: STEP is a randomized clinical trial that compares a vigorous-intensity exercise intervention to a health and wellness education intervention as an aid for smoking cessation in adults with elevated AS. One hundred and fifty eligible participants will receive standard treatment (ST) for smoking cessation that includes cognitive behavioral therapy (CBT) and nicotine replacement therapy (NRT). In addition, participants will be randomly assigned to either an exercise intervention (ST+EX) or a health and wellness education intervention (ST+CTRL). Participants in both arms will meet 3 times a week for 15 weeks, receiving CBT once a week for the first 7 weeks, and 3 supervised exercise or health and wellness education sessions (depending on randomization) per week for the full 15-week intervention. Participants will be asked to set a quit date for 6 weeks after the baseline visit, and smoking cessation outcomes as well as putative mediator variables will be measured up to 6 months following the quit date.
Discussion: The primary objective of STEP is to evaluate whether vigorous-intensity exercise can aid smoking cessation in anxiety vulnerable adults. If effective, the use of vigorous-intensity exercise as a component of smoking cessation interventions would have a significant public health impact. Specifically, in addition to improving smoking cessation treatment outcome, exercise is expected to offer benefits to overall health, which may be particularly important for smokers. The study is also designed to test putative mediators of the intervention effects and therefore has the potential to advance the understanding of exercise-anxiety-smoking relations and guide future research on this topic
Two contemporaneous mitogenomes from terminal Pleistocene burials in eastern Beringia
Pleistocene residential sites with multiple contemporaneous human burials are extremely rare in the Americas. We report mitochondrial genomic variation in the first multiple mitochondrial genomes from a single prehistoric population: two infant burials (USR1 and USR2) from a common interment at the Upward Sun River Site in central Alaska dating to ~11,500 calendar years before present (cal B.P.). Using a targeted capture method and next-generation sequencing we determined that the USR1 infant possessed variants that define mitochondrial lineage C1b, while the USR2 genome falls at the root of lineage B2, allowing us to refine younger coalescence age estimates for these two clades. C1b and B2 are rare to absent in modern populations of Northern North America. Documentation of these lineages at this location in the Late Pleistocene provides evidence for the extent of mitochondrial diversity in early Beringian populations, which supports the expectations of the Beringian Standstill Model
Blind Test of Methods for Obtaining 2-D Near-Surface Seismic Velocity Models from First-Arrival Traveltimes
Seismic refraction methods are used in environmental and engineering studies to image the
shallow subsurface. We present a blind test of inversion and tomographic refraction analysis
methods using a synthetic first-arrival-time dataset that was made available to the community in
2010. The data are realistic in terms of the near-surface velocity model, shot-receiver geometry
and the data’s frequency and added noise. Fourteen estimated models were determined by ten
participants using eight different inversion algorithms, with the true model unknown to the
participants until it was revealed at a session at the 2011 SAGEEP meeting. The estimated
models are generally consistent in terms of their large-scale features, demonstrating the
robustness of refraction data inversion in general, and the eight inversion algorithms in
particular. When compared to the true model, all of the estimated models contain a smooth
expression of its two main features: a large offset in the bedrock and the top of a steeply dipping
low-velocity fault zone. The estimated models do not contain a subtle low-velocity zone and
other fine-scale features, in accord with conventional wisdom. Together, the results support
confidence in the reliability and robustness of modern refraction inversion and tomographic
Methods
Phosphorylation State of Olig2 Regulates Proliferation of Neural Progenitors
SummaryThe bHLH transcription factors that regulate early development of the central nervous system can generally be classified as either antineural or proneural. Initial expression of antineural factors prevents cell cycle exit and thereby expands the pool of neural progenitors. Subsequent (and typically transient) expression of proneural factors promotes cell cycle exit, subtype specification, and differentiation. Against this backdrop, the bHLH transcription factor Olig2 in the oligodendrocyte lineage is unorthodox, showing antineural functions in multipotent CNS progenitor cells but also sustained expression and proneural functions in the formation of oligodendrocytes. We show here that the proliferative function of Olig2 is controlled by developmentally regulated phosphorylation of a conserved triple serine motif within the amino-terminal domain. In the phosphorylated state, Olig2 maintains antineural (i.e., promitotic) functions that are reflected in human glioma cells and in a genetically defined murine model of primary glioma
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