923 research outputs found
Modeling Cle Elum Reservoir Shoreline Erosion: GIS Analysis to Support Cultural and Environmental Resource Management, Yakima Basin, Washington
In the Yakima Basin, managers are expanding reservoirs including Cle Elum Lake to increase the availability of water. The objective of this study was to examine areas prone to further shoreline erosion to inform resource management. This research included the use of airphotos and fieldwork to identify erosional shorelines. Erosion was verified in the field using a video survey as well as indicators such as shoreline slope, sediment size, and nearshore width. Near-term erosional segments were identified by more rapidly receding bluffs while long-term erosional segments included both bedrock cliffs and bluffs. Although most of the shoreline is depositional, near-term bluff erosion is most prevalent along the southeastern and northeastern shorelines while long-term erosion is mainly along the northwestern and southeastern shorelines. Potential erosion control variables were identified in the scientific literature and data representing them were acquired from fieldwork and outside sources. Geologic units and slope intervals are statistically significant variables in shoreline erosion. In the near-term shoreline erosion inventory, low bluffs with sandstone substrates make the largest contribution to the relationship between geologic units and erosional segments. An extensive cliff formed of intrusive igneous rocks is important to the relationship between geologic unit and long-term erosion. Although the nearshore and foreshore zones are largely below 36° reflecting the glacial origins of this basin, intermediate slopes between 11° and 36° and steep slopes between 37° - 49° are mainly responsible for the link between slope intervals and both bluff and cliff erosion. A Geographic Information Systems (GIS) model used these factors to predict relatively limited areas highly susceptible to future erosion, with near-term erosion risk mainly on the eastern and southwestern lakeshore while the southeastern and northwestern shoreline are most susceptible over the long-term. The product of this analysis were hazard maps indicating the relative risk of shoreline erosion. These maps formed the basis of policy recommendations including increased shoreline protection along southeastern shoreline and the implementation of a long-term monitoring program for shoreline erosion to support the management of cultural resources
Structure of turbulence and sediment stratification in wave-supported mud layers
We present results from laboratory experiments in a wave flume with and without a sediment bed to investigate the turbulent structure and sediment dynamics of wave-supported mud layers. The presence of sediment on the bed significantly alters the structure of the wave boundary layer relative to that observed in the absence of sediment, increasing the TKE by more than a factor of 3 at low wave orbital velocities and suppressing it at the highest velocities. The transition between the low and high-velocity regimes occurs when ReÎ â 450, where ReÎ is the Stokes Reynolds number. In the low-velocity regime (ReÎ 450) the ripples are significantly smaller, the near-bed sediment concentrations are significantly higher and density stratification due to sediment becomes important. In this regime the TKE and Reynolds stress are lower in the sediment bed runs than in comparable runs with no sediment. The regime transition at ReÎ = 450 appears to result from washout of the ripples and increased concentrations of fine sand suspended in the boundary layer, which increases the settling flux and the stratification near the bed. The increased stratification damps turbulence, especially near the top of the high-concentration layer, reducing the layer thickness. We anticipate that these effects will influence the transport capacity of wave-supported gravity currents on the continental shelf
A Second Giant Planet in 3:2 Mean-Motion Resonance in the HD 204313 System
We present 8 years of high-precision radial velocity (RV) data for HD 204313
from the 2.7 m Harlan J. Smith Telescope at McDonald Observatory. The star is
known to have a giant planet (M sin i = 3.5 M_J) on a ~1900-day orbit, and a
Neptune-mass planet at 0.2 AU. Using our own data in combination with the
published CORALIE RVs of Segransan et al. (2010), we discover an outer Jovian
(M sin i = 1.6 M_J) planet with P ~ 2800 days. Our orbital fit suggests the
planets are in a 3:2 mean motion resonance, which would potentially affect
their stability. We perform a detailed stability analysis, and verify the
planets must be in resonance.Comment: Accepted for publication in Ap
Formation of elongated starch granules in high-amylose maize
GEMS-0067 maize starch contains up to 32% elongated starch granules, much higher than amylose-extender (ae) single-mutant maize starch (âŒ7%) and normal (non-mutant) maize starch (0%). These elongated granules are highly resistant to enzymatic hydrolysis at 95â100 °C, which function as resistant starch. The structure and formation of these elongated starch granules, however, were not known. In this study, light, confocal laser-scanning, scanning electron, and transmission electron microscopy were used to reveal the structure and formation of these elongated starch granules. The transmission electron micrographs showed fusion through amylose interaction between adjacent small granules in the amyloplast at the early stage of granule development. A mechanistic model for the formation of elongated starch granules is proposed
Sound source contributions for the prediction of vehicle pass-by noise
Road traffic noise contributes to environmental noise, which can result in cardiovascular disease,
sleep disturbance or annoyance for the exposed population1. The reduction of road traffic noise
aims to increase health and life quality. Therefore, the vehicle pass-by noise emission, which is
determined in a standardised test situation, was limited by legislation. First introduced in the 1970s,
vehicle pass-by noise limits have been gradually reduced for all vehicle classes. However, road
traffic noise was not as significantly reduced as the pass-by noise limits
Prediction of vehicle pass-by noise
Environmental noise exposure represents a burden to people and can result in cardiovascular disease, sleep disturbance or annoyance. Road traffic noise is a main contributor to environmental noise, thus, it is intended to be reduced and limited by legislation in order to increase health and life quality.
Vehicle pass-by noise tests are conducted according to the international standard ISO 362, which is suppose to reflect the noise emission of a vehicle in an urban traffic environment. It is discussed that nowadays urban traffic situation requires a change of the test procedure with accompanying reductions in pass-by noise limits. To achieve compliance with the pass-by noise test it is important that vehicle engineers have access to predictive tools at the design stage.
In this paper the initial development of a pass-by noise predictive tool is reported. To begin with, the vehicle pass-by noise test according to standard ISO 362 is summarized. Existing public domain literature is reviewed and an analysis of the characteristics of the four major noise sources (engine, intake and exhaust system, tyre/road system) contributing to pass-by noise is presented. An experimental set-up involving a point source loudspeaker on a moving trolley is described. Experimental measurements made within an anechoic chamber are used as validation data for the predicted pass-by noise
Constraints on the vital effect in coccolithophore and dinoflagellate calcite by oxygen isotopic modification of seawater
Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 141 (2014): 612-627, doi:10.1016/j.gca.2014.05.002.In this study, we show that there are independent controls of 18O/16O and 13C/12C
fractionation in coccolithophore and dinoflagellate calcite due to the contrasting kinetics of
each isotope system. We demonstrate that the direction and magnitude of the oxygen isotope
fractionation with respect to equilibrium is related to the balance between calcification rate
and the replenishment of the internal pool of dissolved inorganic carbon (DIC). As such, in
fast growing cells, such as those of Emiliania huxleyi and Gephyrocapsa oceanica (forming
the so-called âheavy groupâ), calcification of the internal carbon pool occurs faster than
complete isotopic re-adjustment of the internal DIC pool with H2O molecules. Hence,
coccoliths reflect the heavy oxygen isotope signature of the CO2 overprinting the whole DIC
pool. Conversely, in large and slow growing cells, such as Coccolithus pelagicus ssp.
braarudii, complete re-equilibration is achieved due to limited influx of CO2 leading to
coccoliths that are precipitated in conditions close to isotopic equilibrium (âequilibrium
groupâ). Species exhibiting the most negative oxygen isotope composition, such as
Calcidiscus leptoporus (âlight groupâ), precipitate coccolith under increased pH in the
coccolith vesicle, as previously documented by the âcarbonate ion effectâ. We suggest that,
for the carbon isotope system, any observed deviation from isotopic equilibrium is only
âapparentâ, as the carbon isotopic composition in coccolith calcite is controlled by a Rayleigh
fractionation originating from preferential incorporation of 12C into organic matter. Therefore,
species with low PIC/POC ratios as E. huxleyi and G. oceanica are shifted towards positive
carbon isotope values as a result of predominant carbon fixation into the organic matter. By
contrast, cells with higher PIC/POC as C. braarudii and C. leptoporus maintain, to some
extent, the original negative isotopic composition of the CO2. The calcareous dinoflagellate
Thoracosphaera heimii exhibits different behaviour for both isotopic systems, in particular with respect to its very negative carbon isotope composition, owing to coeval intra and
extracellular biomineralisation in this group. In this study, we also investigate the sensitivity
of 18O/16O fractionation to varying ambient oxygen isotope composition of the medium for
inorganic, coccolithophore, and dinoflagellate calcite precipitated under controlled laboratory
conditions. The varying responses of different taxa to increased oxygen isotope composition
of the growth medium may point to a potential bias in sea surface temperature reconstructions
that are based on the oxygen isotopic compositions of sedimentary calcite, especially during
times of changing seawater oxygen isotopic composition. Overall, this study represent an
important step towards establishing a mechanistic understanding of the âvital effectâ in
coccolith and dinoflagellate calcite, and provides valuable information for interpreting the
geochemistry of the calcareous nannofossils in the sedimentary record, at both monospecific
and interspecies levels.MH is grateful to the Natural Environment Research Council (NERC) for funding
through Postdoctoral Fellowship (NE/H015523/1). TJH is supported by the Postdoctoral
Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by the
Doherty Foundation. REMR was supported through European Research Council (ERC) grant
SP2-GA-2008-200915
Design rationale: the rationale and the barriers
ABSTRACT One goal of design rationale systems is to support designers by providing a means to record and communicate the argumentation and reasoning behind the design process. However, there are several inherent limitations to developing systems that effectively capture and utilize design rationale. The dynamic and contextual nature of design and our inability to exhaustively analyze all possible design issues results in cognitive, capture, retrieval, and usage limitations. In addition, there are the organizational limitations that ensue when systems are deployed. In this paper we analyze these issues in terms of current perspectives in design theory and describe the implications to design research. We discuss the barriers to effective design rationale in terms of three major goals: reflection, communication, and analysis of design processes. We then suggest alternate means to achieve these goals that can be used with or instead of design rationale systems. Author Keywords Design rationale, theories of design, interactive systems design. ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous
Reprint of âThe Single-Case Reporting Guideline In BEhavioural interventions (SCRIBE) 2016: explanation and elaborationâ
There is substantial evidence that research studies reported in the scientific literature do not provide adequate information so that readers know exactly what was done and what was found. This problem has been addressed by the development of reporting guidelines which tell authors what should be reported and how it should be described. Many reporting guidelines are now available for different types of research designs. There is no such guideline for one type of research design commonly used in the behavioral sciences, the single-case experimental design (SCED). The present study addressed this gap. This report describes the Single-Case Reporting guideline In BEhavioural interventions (SCRIBE) 2016, which is a set of 26 items that authors need to address when writing about SCED research for publication in a scientific journal. Each item is described, a rationale for its inclusion is provided, and examples of adequate reporting taken from the literature are quoted. It is recommended that the SCRIBE 2016 is used by authors preparing manuscripts describing SCED research for publication, as well as journal reviewers and editors who are evaluating such manuscripts.Published versio
Noise source characteristics in the ISO 362 vehicle pass-by noise test: literature review
Since many people are exposed to road traffic noise in urban areas, current legislation aims
to limit vehicle noise emissions. In Europe, the vehicle pass-by noise test is implemented
according to the international standard ISO 362. As a result of more recent investigations of
urban traffic, a revision to the ISO 362 standard has been proposed that includes a constantspeed
test in addition to the traditional accelerated test in order to determine the pass-by
noise value. To ensure compliance with the pass-by noise test vehicle manufacturers and
suppliers must quantify vehicle noise source characteristics during the design stage of the
vehicle. In addition, predictive tools need to be available during the product development
phase in order to estimate the final pass-by noise level. In this paper an extensive literature
survey is presented of noise source characteristics in the ISO 362 vehicle pass-by noise test.
Vehicle pass-by noise is analysed in the time and frequency domains and a ranking of the
noise source contributions is established. The characteristics of the four major noise sources
(engine, intake system, exhaust system, tyre/road system) contributing to pass-by noise as
well as current prediction methods are reviewed
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