1,691 research outputs found
Greenland Ice Sheet solid ice discharge from 1986 through March 2020
No full textWe present a 1986 through March 2020 estimate of Greenland Ice Sheet ice discharge. Our data include all discharging ice that flows faster than 100myr-1 and are generated through an automatic and adaptable method, as opposed to conventional handpicked gates. We position gates near the present-year termini and estimate problematic bed topography (ice thickness) values where necessary. In addition to using annual timevarying ice thickness, our time series uses velocity maps that begin with sparse spatial and temporal coverage and end with near-complete spatial coverage and 12 d updates to velocity. The 2010 through 2019 average ice discharge through the flux gates is 487±49 Gt yr-1. The 10% uncertainty stems primarily from uncertain ice bed location (ice thickness). We attribute the 50 Gt yr-1 differences among our results and previous studies to our use of updated bed topography from BedMachine v3. Discharge is approximately steady from 1986 to 2000, increases sharply from 2000 to 2005, and then is approximately steady again. However, regional and glacier variability is more pronounced, with recent decreases at most major glaciers and in all but one region offset by increases in the northwest region through 2017 and in the southeast from 2017 through March 2020. As part of the journal's living archive option and our goal to make an operational product, all input data, code, and results from this study will be updated as needed (when new input data are available, as new features are added, or to fix bugs) and made available at https://doi.org/10.22008/promice/data/ice-discharge (Mankoff, 2020a) and at https://github.com/mankoff/ice-discharge (last access: 6 June 2020, Mankoff, 2020e)
Prenatal care advice to see a dentist: results from a population-based study
No full textMeredith L. Vandermeer (Department of Public Health, Oregon State University), Kenneth D. Rosenberg (Office of Family Health, Oregon Department of Human Services), Alfredo P. Sandoval (Oregon Health & Science University).Title from PDF caption (viewed on August 14, 2020).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
Impact of scour on lateral resistance of wind turbine monopiles: An experimental study
No full textThe majority of offshore wind structures are supported on large-diameter, rigid monopile foundations. These piles may be subjected to scour due to the waves and currents that causes a loss of soil support and consequently decreases the pile capacity and system stiffness. The results of numerical models suggest that the shape of the scour hole affects the magnitude of pile capacity loss; however, there is a dearth of experimental test data that quantify this effect. This paper presents a series of centrifuge model tests on an instrumented model pile that investigates the effects of scour-hole geometry on the response of a laterally loaded pile embedded in sand. The pile instrumentation allowed load–displacement and p–y (soil reaction – displacement) curves to be derived. Three scour geometries (global, local wide, and local narrow) and three scour depths (1D, 1.5D, and 2D; where D is pile diameter) were modelled. For all three scour types, pile moment capacity decreased almost linearly with increase of scour depth. Simple empirical relations were proposed to evaluate the detrimental influence of scour on the pile moment capacity. A new method has been developed to allow designers to quantify the effect of scour-hole shape and severity of scour on the pile response.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Geo-engineerin
Greenland liquid water discharge from 1958 through 2019
No full textpeer reviewedGreenland runoff, from ice mass loss and increasing rainfall, is increasing. That runoff, as discharge, impacts the physical, chemical, and biological properties of the adjacent fjords. However, where and when the discharge occurs is not readily available in an open database. Here we provide data sets of high-resolution Greenland hydrologic outlets, basins, and streams, as well as a daily 1958 through 2019 time series of Greenland liquid water discharge for each outlet. The data include 24 507 ice marginal outlets and upstream basins and 29 635 land coast outlets and upstream basins, derived from the 100 m ArcticDEM and 150 m BedMachine. At each outlet there are daily discharge data for 22 645 d – ice sheet runoff routed subglacially to ice margin outlets and land runoff routed to coast outlets – from two regional climate models (RCMs; MAR and RACMO). Our sensitivity study of how outlet location changes for every inland cell based on subglacial routing assumptions shows that most inland cells where runoff occurs are not highly sensitive to those routing assumptions, and outflow location does not move far. We compare RCM results with 10 gauges from streams with discharge rates spanning 4 orders of magnitude. Results show that for daily discharge at the individual basin scale the 5 % to 95 % prediction interval between modeled discharge and observations generally falls within plus or minus a factor of 5 (half an order of magnitude, or +500 %/−80 %). Results from this study are available at https://doi.org/10.22008/promice/freshwater (Mankoff, 2020a) and code is available at http://github.com/mankoff/freshwater (last access: 6 November 2020) (Mankoff, 2020b)
Greenland Freshwater Flux on Glacier-basin Scales
No full textThis dataset contains derived mass loss data from marine-terminating glaciers in Greenland on a monthly timescale from 2010 up to and including 2020.
Reference: Karlsson et al., 202, GEUS Bulletin (DOI: 10.34194/geusb.v53.833)
File structure:
Data for each glacier outlet are stored as csv (comma separated values) that can be opened in Excel or loaded into Matlab, python etc.
Files are named as
glaciername_region_GateID.csv
A note on glacier names: In our dataset, glacier name is the official name in Greenlandic (following Bjoerk et al., 2015), region is the region of Greenland (following Mouginot and Rignot, 2019) and GateID is the ID of the discharge gate from Mankoff et al. 2020. We also list the names as used by Mouginot and Rignot (2019) but we advise against using those names in formal literature as they are not approved by the Greenland Language Secretariat.
Multiple glaciers have no official name. They are listed as "Unknown".
Some glacier names contain letters that are not easily machine-readable. We have made the following substitutions to ease the use of the data:
Danish letters
æ = ae
ø = oe
å = aa
Other letters
ö = ooe (Nordenskiöld)
ü = ue (Brückner)
Data
The data consist of the following volume loss terms :
Runoff
Ice discharge
Basal melt
Total Volume loss
The surface melt is derived from a regional climate model. The ice discharge stems from satellite observations of ice velocities. The basal melt is constructed from a combination of models and derived geothermal heat flux values. Please see Karlsson et al., 2023 and references therein for information on the individual volume loss terms.
Using the dataset
Users wishing to know the mass loss terms from a glacier basin may simply locate the csv-file with the corresponding glacier name in the datafolder.
PLEASE NOTE: Some glaciers have more than one csv-file. This is because they have more than one branch of glacier flow. The total freshwater flux into a fjord from the glacier will then be the combined volume loss from all cvs files with the glacier name. E.g., the glacier Akullikassaap Sermia in northwestern Greenland has two discharge gates #133 and #134. The total output from Akullikassaap Sermia is then the sum of the terms in AkullikassaapSermia_NW_D133.csv and AkullikassaapSermia_NW_D134.csv.
Users who do not know the glacier name may instead load the Geopackage file GlacierGates in a GIS software. The shapefile displays the location of each discharge gate and contains information on the glacier name, data filename, and the decadal mean of each volume loss term.
The shapefile contains the following abbreviations:
Ice discharge: abbreviated Ice dis.
Basal melt: abbreviated Basal
Total Volume loss: abbreviated Total los
HUMAN CAPITAL ASSESSMENT INDICATORS AS INFLUENTIAL DETERMINANTS PERTAINING TO THE ADMISSION CRITERIA UTILIZED BY PRE-LICENSURE PROGRAMS FOR NURSING EDUCATION
No full textThe attainment of educational credentials contributes to the acquisition of human capital. Academic preparedness is a component therein that allows for the attainment of increased levels of education. Most institutions of higher education utilize measures of academic preparedness, such as grade point averages or standardized tests. Requirements for the levels of academic preparedness are based upon many factors. The requirements most relevant to this study are the selectivity of the institution and the academic preparedness of potential candidates of pre-licensure programs for nursing education.
The pre-licensure education of nurses is enigmatic when compared to other professional disciplines. Pre-licensure education for registered nurses exists in three distinct and differently classified programs: a hospital-based diploma program, an associate degree program, or a baccalaureate program. (There is an additional baccalaureate program, known as accelerated second degree programs, for students possessing a baccalaureate degree in another discipline. These accelerated programs are not included in this discussion.) The National Center for Education Statistics classifies each of the three programs, making clear that the differing program levels of post-secondary education are neither equivalent nor interchangeable.
According to the literature, the academic preparedness of individuals and the level of selectivity of higher education institutions vary greatly depending upon the particular classification of nursing program. What then, is the level of programmatic selectivity, given that all three pre-licensure programs produce candidates for the identical occupational certification while attracting candidates known to have varying levels of academic preparedness? This study aimed to determine the levels of selectivity of the three pre-licensure nursing education programs types so as identify trends and patterns within and across pre-licensure program types. In order to determine these trends and patterns, the author examined the admissions requirements that are transparent to the public on schools’ websites in which these programs are housed, employing the methodology of document analysis. The determination for the level of selectivity was based upon Barron’s Measure of Selectivity (Barron’s Educational Series, 2011)
Charmonium levels near threshold and the narrow state X(3872)->pi(+)pi(-)J/psi
No full textWe explore the influence of open-charm channels on charmonium properties and profile the 1^3D2, 1^3D3, and 2^1P1 charmonium candidates for X(3872). The favored candidates, the 1^3D2 and 1^3D3 levels, both have prominent radiative decays. The 1^3D2 might be visible in the D0D*0 channel, while the dominant decay of the 1^3D3 state should be into D¯D. We propose that additional discrete charmonium levels can be discovered as narrow resonances of charmed and anticharmed mesons.First author draf
Evaluating carbon offsets from forestry and energy projects
No full textUnder the Kyoto Protocol, industrial countries accept caps on their emissions of greenhouse gases. They are permitted to acquire offsetting emissions reductions from developing countries - which do not have emissions limitations - to assist in complying with these caps. Because these emissions reductions are defined against a hypothetical baseline, practical issues arise in ensuring that the reductions are genuine. Forestry-related emissions reduction projects are often thought to present greater difficulties in measurement and implementation, than energy-related emissions reduction projects. The author discusses how project characteristics affect the process for determining compliance with each of the criteria for qualifying. Those criteria are: 1) Additionality. Would these emissions reductions not have taken place without the project? 2) Baseline and systems boundaries (leakage). What would business-as-usual emissions have been without the project? And in this comparison, how broad should spatial, and temporal system boundaries be? 3) Measurement (or sequestration). How accurately can we measure actual with-project emissions levels? 4) Duration or permanence. Will the project have an enduring mitigating effect? 5) Local impact. Will the project benefit its neighbors? For all the criteria except permanence, it is difficult to find generic distinctions between land use change and forestry and energy projects, since both categories comprise diverse project types. The important distinctions among projects have to do with such things as: a) The level and distribution of the project's direct financial benefits. b) How much the project is integrated with the larger system. c) The project components'internal homogeneity and geographic dispersion. d) The local replicability of project technologies. Permanence is an issue specific to land use and forestry projects. The author describes various approaches to ensure permanence, or adjust credits for duration: the ton-year approach (focusing on the benefits from deferring climatic damage, and rewarding longer deferral); the combination approach (bundling current land use change and forestry emissions reductions with future reductions in the buyer's allowed amount); a technology-acceleration approach; and an insurance approach.Montreal Protocol,Environmental Economics&Policies,Climate Change,Decentralization,Global Environment Facility,Environmental Economics&Policies,Energy and Environment,Carbon Policy and Trading,Montreal Protocol,Climate Change
Scripts
No full textScripts used to calculate average pairwise differences between all 6 pairwise combinations along the XR chromosome between Drosophila pseudoobscura, Drosophila persimilis, Sex-Ratio Drosophila persimilis, and Drosophila miranda. These output file can then be used to calculate RND between
D pseudoobscura, D persimilis, and SR D persimilis in another program such as Microsoft Excel. All scripts are written in Perl. Author: Kenneth Hoehn. Date: May-5-2011. Sections: 1. Constructing the combined, raw input file from PILEUP outputs (skip if combined input file is provided); 2. Necessary input files for final analysis; 3. Editing combined input file and calculating average pairwise differences; 4. Calculating RND; 5. Double checking output; 6. Simple window writing script. See README.txt for more details
Centrifuge modeling of the impact of local and global scour erosion on the monotonic lateral response of a monopile in sand
No full textCopyright © 2020 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. The majority of offshore wind turbines are founded on large-diameter, open-ended steel monopiles. Monopiles must resist lateral loads and overturning moments because of environmental (wind and wave) actions, whereas vertical loads tend to be comparatively small. Recent developments in turbine sizes and increases in hub heights have resulted in pile diameters increasing rapidly, whereas the embedment length to diameter ratio (L/D) is reducing. Soil erosion around piles, termed scour, changes the soil strength and stiffness properties and affects the system's load resistance characteristics. In practice, design scour depths of up to 1.3D are routinely assumed during the turbine lifetime; however, the impact on monopiles with low L/D is not yet fully understood. In this article, centrifuge tests are performed to assess the effect of scour on the performance of piles with low L/D. In particular, the effect of combined loads, scour type (global, local), and depth are considered. A loading system is developed that enables application of realistic load eccentricity and combined vertical, horizontal, and moment loading at the seabed level. An instrumented 1.8-m-diameter pile with L/D = 5 is used. A friction-reducing ball-type connection is designed to transfer lateral loads to the pile without inducing any rotational pile-head constraint, which is associated with loading rigs in tests of this nature. Results suggest that vertical and lateral load interaction is minimal. Scour has a significant impact on the lateral load-bearing capacity and stiffness of the pile, leads to increases in bending moment magnitude along the pile shaft, and lowers the location of peak pile bending moment. The response varies with scour type, with global scour resulting in larger moments than local scour. The size of the local scour hole is found to have a significant impact on the pile response, suggesting that scour hole width should be explicitly considered in design
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