1,748 research outputs found

    Toward Five-dimensional Core-collapse Supernova Simulations

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    The computational difficulty of six-dimensional neutrino radiation hydrodynamics has spawned a variety of approximations, provoking a long history of uncertainty in the core-collapse supernova explosion mechanism. Under the auspices of the Terascale Supernova Initiative, we are honoring the physical complexity of supernovae by meeting the computational challenge head-on, undertaking the development of a new adaptive mesh refinement code for self-gravitating, six-dimensional neutrino radiation magnetohydrodynamics. This code--called {\em GenASiS,} for {\em Gen}eral {\em A}strophysical {\em Si}mulation {\em S}ystem--is designed for modularity and extensibility of the physics. Presently in use or under development are capabilities for Newtonian self-gravity, Newtonian and special relativistic magnetohydrodynamics (with `realistic' equation of state), and special relativistic energy- and angle-dependent neutrino transport--including full treatment of the energy and angle dependence of scattering and pair interactions.Comment: 5 pages. Proceedings of SciDAC 2005, Scientific Discovery through Advanced Computing, San Francisco, CA, 26-30 June 200

    Shelf MIxed Layer Experiment (SMILE) program description and coastal and moored array data report

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    The Shelf MIxed Layer Experiment (SMILE) was designed to study the response of the oceanic surface boundary layer over the continental shelf to atmospheric forcing. The SMILE field program was conducted over the northern California shelf between Pt. Arena and Pt. Reyes from mid-November 1988 to mid-May 1989. The field program consisted of five main components: (a) a long-term moored array to obtain current, temperature, and conductivity time series observations in the upper ocean over the shelf; (b) a short-term moored instrument deployment to measure the vertical current shear and stratification in the top 6 m of the water column; (c) shipboard CTD and acoustic Doppler current profiler (ADCP) surveys over the shelf and adjacent slope to map regional water property and current distributions; (d) a long-term moored and coastal meteorological array including one sounding station to obtain time series observations of the atmospheric surface forcing and monitor the structure of the marine boundary layer; and (e) overflights with an instrumented aircraft to measure the spatial structure of the surface wind, wind stress, and heat flux fields under different atmospheric conditions. This report has two objectives: (a) to describe the SMILE field program, including overviews of the five components, and (b) to present a statistical and graphical summary of the atmospheric (wind, air temperature, pressure, relative humidity, short- and longwave radiation) and oceanic (current, water temperature, and conductivity) long-term array measurements made as part of SMILE. A more detailed description of the instrumentation used in SMILE and an assessment of instrument performance and accuracy are presented separately by Dean et al. (1991).Funding was provided by the National Science Foundation through Grant No. OCE-87-16937

    Misidentifications in the ARC spectra of the rare earths

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    Environmental controls on daytime net community calcification on a Red Sea reef flat

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    Coral growth and carbonate accumulation form the foundation of the coral reef ecosystem. Changes in environmental conditions due to coastal development, climate change, and ocean acidification may pose a threat to net carbonate production in the near future. Controlled laboratory studies demonstrate that calcification by corals and coralline algae is sensitive to changes in aragonite saturation state (Ωa), as well as temperature, light, and nutrition. Studies also show that the dissolution rate of carbonate substrates is impacted by changes in carbonate chemistry. The sensitivity of coral reefs to these parameters must be confirmed and quantified in the natural environment in order to predict how coral reefs will respond to local and global changes, particularly ocean acidification. We estimated the daytime hourly net community metabolic rates, both net community calcification (NCC) and net community productivity (NCP), at Sheltered Reef, an offshore platform reef in the central Red Sea. Average NCC was 8 ± 3 mmol m[superscript −2] h[superscript −1] in December 2010 and 11 ± 1 mmol m[superscript −2] h[superscript −1] in May 2011, and NCP was 21 ± 7 mmol m[superscript −2] h[superscript −1] in December 2010 and 44 ± 4 mmol m[superscript −2] h[superscript −1] in May 2011. We also monitored a suite of physical and chemical properties to help relate the rates at Sheltered Reef to published rates from other sites. While previous research shows that short-term field studies investigating the NCC–Ωa relationship have differing results due to confounding factors, it is important to continue estimating NCC in different places, seasons, and years, in order to monitor changes in NCC versus Ω in space and time, and to ultimately resolve a broader understanding of this relationship.National Science Foundation (U.S.) (Graduate Research Fellowship

    Status of Acropora palmata Populations off the Coast of South Caicos, Turks and Caicos Islands

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    This study is the first detailed assessment of A. palmata populations of the Turks and Caicos Islands. A total of 203 individual colonies and 62 thickets were tagged on five shallow reefs. Depth, percentages of living tissue, recent mortality and old skeleton were estimated. Presence of disease and predatory snails was noted, and disease spread and grazing rates of the snails estimated. Colonies were found in depths of 0.2 - 4 m. Living tissue for individual colonies (75.9% ± 2.2 SE) was significantly greater than for thickets (58.6% ± 3.6) and in both cases exceeded old skeleton (individuals: 22.7% ± 2.1 SE, thickets: 38.0% ± 3.4 SE). Percentage of recent mortality was very low (individuals: 1.3% ± 0.3 SE, thickets: 3.4% ± 0.7%). We found WBD (n = 2), white pox disease a (WPDa) (n = 7) and white pox disease b (WPDb) (n = 14) with greatly varying spreading rates. The WBD infected colonies showed an atypical spread from the top of the branch towards the base. Coralliophila abbreviata and C. caribaea affected 3 .7 54.7% of the populations (grazing rate: 4.29 cm 2 /day/snail ± 1.16 SE). South Caicos’ A. palmata populations are still in good condition, though increasing human disturbances combined with disease and predatory snails may threaten these populations

    Physical processes determine spatial structure in water temperature and residence time on a wide reef flat

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    Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 125(12), (2020): e2020JC016543, https://doi.org/10.1029/2020JC016543.On coral reefs, flow determines residence time of water influencing physical and chemical environments and creating observable microclimates within the reef structure. Understanding the physical mechanisms driving environmental variability on shallow reefs, which distinguishes them from the open ocean, is important for understanding what contributes to thermal resilience of coral communities and predicting their response to future anomalies. In June 2014, a field experiment conducted at Dongsha Atoll in the northern South China Sea investigated the physical forces that drive flow over a broad shallow reef flat. Instrumentation included current and pressure sensors and a distributed temperature sensing system, which resolved spatially and temporally continuous temperature measurements over a 3‐km cross‐reef section from the lagoon to reef crest. Spectral analysis shows that while diurnal variability was significant across the reef flat—a result expected from daily solar heating—temperature also varied at higher frequencies near the reef crest. These spatially variable temperature regimes, or thermal microclimates, are influenced by circulation on the wide reef flat, with spatially and temporally variable contributions from tides, wind, and waves. Through particle tracking simulations, we find the residence time of water is shorter near the reef crest (3.6 h) than near the lagoon (8.6 h). Tidal variability in flow direction on the reef flat leads to patterns in residence time that are different than what would be predicted from unidirectional flow. Circulation on the reef also determines the source (originating from offshore vs. the lagoon) of the water present on the reef flat.We thank S. Tyler, and J. Selker from the Center for Transformative Environmental Monitoring Programs (CTEMPs), funded by the National Science Foundation (EAR awards 1440596 and 1440506), for timely and effective provision of experimental design support, logistical support and equipment for the project. Support for S. Lentz is from NSF Grant No. OCE‐1558343. Support for A. Cohen from NSF Grant No. 1220529, by the Academia Sinica (Taiwan) through a thematic project grant to G. Wong and A. Cohen. Support for E. Reid and K. Davis is from National Science Foundation (NSF) Grant No. OCE‐1753317, and support to E. Reid from the Environmental Engineering Henry Samueli Endowed Fellowship and the UCI Oceans Graduate Fellowship.2021-05-2

    A multidisciplinary Amazon Shelf SEDiment Study (AmasSeds) : physical oceanography moored array component

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    A Multidisciplinary Amazon Shelf SEDiment Study (AmasSeds) is a cooperative research program by geological, chemical, physical, and biological oceanographers from Brazil and the United States to study sedimentary processes occurring over the continental shelf near the mouth of the Amazon River. The physical oceanography component of AmasSeds included a moored array deployed on the continental shelf approximately 300km northwest of the Amazon River mouth near 3.5°N. The moored array consisted of a cross-shelf transect of three mooring sites located on the 18-m, 65-m, and 103-m isobaths. The moored array was deployed for approximately 4 months, from early February, 1990 to mid-June, 1990, obtaining time series measurements of current, temperature, conductivity, and wind. This report describes the physical oceanography moored array component and provides a statistical and graphical summary of the moored observations.Funding was provided by the National Science Foundation through Grant Nos. OCE 88-12917 and OCE 91-15712

    Quantitative analysis of cell types during growth and morphogenesis in Hydra

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    Tissue maceration was used to determine the absolute number and the distribution of cell types in Hydra. It was shown that the total number of cells per animal as well as the distribution of cells vary depending on temperature, feeding conditions, and state of growth. During head and foot regeneration and during budding the first detectable change in the cell distribution is an increase in the number of nerve cells at the site of morphogenesis. These results and the finding that nerve cells are most concentrated in the head region, diminishing in density down the body column, are discussed in relation to tissue polarity

    Statistical Similarities Between WSA‐ENLIL+Cone Model and MAVEN in Situ Observations From November 2014 to March 2016

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    Normal solar wind flows and intense solar transient events interact directly with the upper Martian atmosphere due to the absence of an intrinsic global planetary magnetic field. Since the launch of the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, there are now new means to directly observe solar wind parameters at the planet’s orbital location for limited time spans. Due to MAVEN’s highly elliptical orbit, in situ measurements cannot be taken while MAVEN is inside Mars’ magnetosheath. To model solar wind conditions during these atmospheric and magnetospheric passages, this research project utilized the solar wind forecasting capabilities of the WSA‐ENLIL+Cone model. The model was used to simulate solar wind parameters that included magnetic field magnitude, plasma particle density, dynamic pressure, proton temperature, and velocity during a four Carrington rotation‐long segment. An additional simulation that lasted 18 Carrington rotations was then conducted. The precision of each simulation was examined for intervals when MAVEN was in the upstream solar wind, that is, with no exospheric or magnetospheric phenomena altering in situ measurements. It was determined that generalized, extensive simulations have comparable prediction capabilities as shorter, more comprehensive simulations. Generally, this study aimed to quantify the loss of detail in long‐term simulations and to determine if extended simulations can provide accurate, continuous upstream solar wind conditions when there is a lack of in situ measurements.Plain Language SummaryIf we ever have a manned mission to Mars, one of the numerous concerns would be space weather conditions and their effects on spacecraft in flight. One particular element of space weather that we like to focus on is solar wind: plasma that is continuously emitted from the Sun. Solar wind can effect communication between Earth and spacecraft, GPS services, and other vital elements of space travel. We therefore want a good understanding of space weather and want to forecast conditions before ever traveling there. Currently, there are not always means to directly measure solar wind, so we rely on numerical models. In this study, we used the model called WSA‐ENLIL+Cone to compare its solar wind measurements and one of our spacecraft orbiting Mars to see how well it did and to see if we can rely on it for solar wind forecasts. As it turns out, the model can be used for forecasting baseline values of different solar wind parameters, for example, temperature, even with limited information. We show in this study that the WSA‐ENLIL+Cone model allows us to forecast solar wind conditions and helps us to understand what is going on at that seemingly barren planet.Key PointsGeneralized, extensive WEC model simulations provide analogous confidence levels and results as detailed, relatively short simulationsWSA‐ENLIL+Cone model succeeds at predicting fast solar wind radial velocityPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142959/1/swe20547.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142959/2/swe20547_am.pd

    Promoting sustainability in quality improvement: an evaluation of a web-based continuing education program in blood pressure measurement.

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    BACKGROUND: The accuracy of blood pressure measurement is variable in office-based settings. Even when staff training programs are effective, knowledge and skills decay over time, supporting the need for ongoing staff training. We evaluated whether a web-based continuing education program in blood pressure measurement reinforced knowledge and skills among clinical staff and promoted sustainability of an existing quality improvement program. METHODS: Medical assistants and nurses at six primary care clinics within a health system enrolled in a 30-min online educational program designed to refresh their knowledge of blood pressure measurement. A 20-question pre- and post-intervention survey addressed learners\u27 knowledge and attitudes. Direct observation of blood pressure measurement technique before and after the intervention was performed. Differences in responses to pre- and post-module knowledge and attitudes questions and in observation data were analyzed using chi-square tests and simple logistic regression. RESULTS: All 88 clinical staff members participated in the program and completed the evaluation survey. Participants answered 80.6% of questions correctly before the module and 93.4% afterwards (p \u3c 0.01). Scores improved significantly among staff from all job types. Licensed practical nurses and staff who had been in their current job at least a year were more likely to answer questions correctly than registered nurses and those in their current job less than a year. Attitudes toward correct blood pressure measurement were high at baseline and did not improve significantly. Prior to the intervention, staff adhered to 9 of 18 elements of the recommended technique during at least 90% of observations. Following the program, staff was more likely to explain the protocol, provide a rest period, measure an average blood pressure, and record the average blood pressure, but less likely to measure blood pressure with the arm at heart level and use the right arm. CONCLUSIONS: We designed, implemented, and evaluated a web-based educational program to improve knowledge, skills, and attitudes in blood pressure measurement and use of an automated device among nurses and medical assistants in ambulatory care. The program reinforced knowledge related to recommended blood pressure measurement technique. TRIAL REGISTRATION: Retrospectively registered with ClincalTrials.gov on March 22, 2012; registration number NCT01566864
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