scholarly journals Large Uncertainty in Estimating p CO2 From Carbonate Equilibria in Lakes

2017 ◽  
Vol 122 (11) ◽  
pp. 2909-2924 ◽  
Author(s):  
Malgorzata Golub ◽  
Ankur R. Desai ◽  
Galen A. McKinley ◽  
Christina K. Remucal ◽  
Emily H. Stanley
Keyword(s):  
Large Uncertainty ◽  
Carbonate Equilibria

Chemical Composition and Metal Speciation in Porewaters from the Upper Qu’Appelle River Basin, Saskatchewan

1993 ◽  
Vol 28 (1) ◽  
pp. 83-110 ◽  
Author(s):  
Richard E. Farrell ◽  
Jae E. Yang ◽  
P. Ming Huang ◽  
Wen K. Liaw
Keyword(s):  
Amino Acids ◽  
Trace Metal ◽  
River Basin ◽  
Drainage Basin ◽  
Metal Speciation ◽  
Anthropogenic Activities ◽  
High Concentration ◽  
Metal Concentrations ◽  
Carbonate Equilibria ◽  
The Impact

Abstract Porewater samples from the upper Qu’Appelle River basin in Saskatchewan, Canada, were analyzed to obtain metal, inorganic ligand and amino add profiles. These data were used to compute the aqueous speciation of the metals in each porewater using the computer program GEOCHEM-PC. The porewaters were classified as slightly to moderately saline. Metal concentrations reflected both the geology of the drainage basin and the impact of anthropogenic activities. Whereas K and Na were present almost entirely as the free aquo ions, carbonate equilibria dominated the speciation of Ca. Mg and Mn (the predominant metal ligand species were of the type MCO3 (s). MCO30. and MHCO3+). Trace metal concentrations were generally within the ranges reported for non-polluted freshwater systems. Whereas the speciation of the trace metals Cr(III) and Co(II) was dominated by carbonate equilibria, Hg(II)-, Zn(II)- and Fe(II)-speciation was dominated by hydroxy-metal complexes of the type M(OH)+ and M(OH)2°. The speciation of Fe(III) was dominated by Fe(OH)3 (s). In porewaters with high chloride concentrations (> 2 mM), however, significant amounts of Hg(II) were bound as HgCl20 and HgClOH0. The aqueous speciation of Al was dominated by Al(OH)4− and Al2Si2O4(OH)6 (s). Total concentrations of dissolved free amino acids varied from 15.21 to 25.17 umole L−1. The most important metal scavenging amino acids were histidine (due to high stability constants for the metal-histidine complexes) and tryptophan (due to its relatively high concentration in the porewaters. i.e., 5.96 to 7.73 umole L−1). Secondary concentrations of various trace metal-amino add complexes were computed for all the porewaters, but metal-amino acid complexes dominated the speciation of Cu(II) in all the porewaters and Ni(II) in two of the porewaters.

scholarly journals Asymmetric dynamics between uncertainty and unemployment flows in the United States

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ali Ahmed ◽  
Mark Granberg ◽  
Victor Troster ◽  
Gazi Salah Uddin
Keyword(s):  
United States ◽  
Business Cycle ◽  
Negative Impact ◽  
The United States ◽  
Large Uncertainty ◽  
Monthly Data ◽  
Uncertainty Measures ◽  
Linear And Nonlinear ◽  
The Business Cycle ◽  
The U.S

AbstractThis paper examines how different uncertainty measures affect the unemployment level, inflow, and outflow in the U.S. across all states of the business cycle. We employ linear and nonlinear causality-in-quantile tests to capture a complete picture of the effect of uncertainty on U.S. unemployment. To verify whether there are any common effects across different uncertainty measures, we use monthly data on four uncertainty measures and on U.S. unemployment from January 1997 to August 2018. Our results corroborate the general predictions from a search and matching framework of how uncertainty affects unemployment and its flows. Fluctuations in uncertainty generate increases (upper-quantile changes) in the unemployment level and in the inflow. Conversely, shocks to uncertainty have a negative impact on U.S. unemployment outflow. Therefore, the effect of uncertainty is asymmetric depending on the states (quantiles) of U.S. unemployment and on the adopted unemployment measure. Our findings suggest state-contingent policies to stabilize the unemployment level when large uncertainty shocks occur.

scholarly journals Probabilistic Performance Assessment vs. the Safety Case Approach

MRS Advances ◽  
2019 ◽  
Vol 4 (17-18) ◽  
pp. 987-992
Author(s):  
François Diaz-Maurin ◽  
Rodney C. Ewing
Keyword(s):  
Performance Assessment ◽  
Uncertainty Quantification ◽  
International Community ◽  
Regulatory Framework ◽  
Geologic Repository ◽  
Large Uncertainty ◽  
Safety Case ◽  
The Face ◽  
The U.S

ABSTRACTThe “safety case” approach has been developed to address the issue of evaluating the performance of a geologic repository in the face of the large uncertainty that results for evaluations that extend over hundreds of thousands of years. This paper reviews the concept of the safety case as it has been defined by the international community. We contrast the safety case approach with that presently used in the U.S. repository program. Especially, we focus on the role of uncertainty quantification. There are inconsistencies between the initial proposal to dealing with uncertainties in a safety case and current U.S. practice. The paper seeks to better define the safety case concept so that it can be usefully applied to the regulatory framework of the U.S. repository program.

scholarly journals Chemical Models of Solute Acquisition in Glacial Melt Waters

1984 ◽  
Vol 30 (104) ◽  
pp. 49-57 ◽  
Author(s):  
R. Raiswell
Keyword(s):  
Closed System ◽  
Mineral Weathering ◽  
Hydrogen Ion ◽  
Mixing Ratio ◽  
System Models ◽  
Chemical Models ◽  
Rock Mineral ◽  
Carbonate Equilibria ◽  
Solute Acquisition ◽  
Final Composition

AbstractChemical models for the evolution of bulk melt waters can be constructed by assuming that rock mineral weathering and solute acquisition are controlled by carbonate equilibria. Different open- and closed- system models are defined by variations in the rates of weathering relative to the rate of hydrogen-ion supply by the dissolution and dissociation of CO2, and can be recognized by characteristic pH and ∑+relationships. The observed and inferred compositions of englacial and subglacial melt suggest that mixing is unlikely to be conservative and that closed-system conditions result where post-mixing weathering reactions occur. The final composition of bulk melt waters is determined by the mixing ratio between englacial and subglacial melt, the extent of post-mixing evolution, and opportunity for mixing with ground waters or re-equilibration with the atmosphere.

scholarly journals Large uncertainty in permafrost carbon stocks due to hillslope soil deposits

2017 ◽  
Vol 44 (12) ◽  
pp. 6134-6144 ◽  
Author(s):  
Eitan Shelef ◽  
Joel C. Rowland ◽  
Cathy J. Wilson ◽  
G. E. Hilley ◽  
Umakant Mishra ◽  
...  
Keyword(s):  
Carbon Stocks ◽  
Large Uncertainty ◽  
Soil Deposits

scholarly journals Propagation of large uncertainty sets in orbital dynamics by automatic domain splitting

2015 ◽  
Vol 122 (3) ◽  
pp. 239-261 ◽  
Author(s):  
Alexander Wittig ◽  
Pierluigi Di Lizia ◽  
Roberto Armellin ◽  
Kyoko Makino ◽  
Franco Bernelli-Zazzera ◽  
...  
Keyword(s):  
Orbital Dynamics ◽  
Large Uncertainty ◽  
Uncertainty Sets

scholarly journals Astronomical phenomena in Dresden codex

2013 ◽  
pp. 53-64
Author(s):  
V. Böhm ◽  
B. Böhm ◽  
J. Klokocník ◽  
J. Vondrák ◽  
J. Kostelecký
Keyword(s):  
Historical Data ◽  
Large Uncertainty ◽  
Astronomical Data ◽  
Julian Date ◽  
History Of ◽  
Solar Eclipses ◽  
Dresden Codex ◽  
The Relationship

The relationship between Maya and our calendar is expressed by a coefficient known as ?correlation? which is a number of days that we have to add to the Mayan Long Count date to get Julian Date used in astronomy. There is surprisingly large uncertainty in the value of the correlation, yielding a shift between both calendars (and thus between the history of Maya and of our world) to typically several hundred years. There are more than 50 diverse values of the correlation, some of them derived from historical, other by astronomical data. We test here (among others) the well established Goodman-Mart?nez-Thompson correlation (GMT), based on historical data, and the B?hms? one (B&B), based on astronomical data decoded from the Dresden Codex (DC); this correlation differs by about +104 years from the GMT. In our previous works we used several astronomical phenomena as recorded in the DC for a check. We clearly demonstrated that (i) the GMT was not capable to predict these phenomena that really happened in nature and (ii) that the GMT predicts them on the days when they did not occur. The phenomena used till now in the test are, however, short-periodic and the test then may suffer from ambiguity. Therefore, we add long-periodic astronomical phenomena, decoded successfully from the DC, to the testing. These are (i) a synchrony of Venusian heliacal risings with the solar eclipses, (ii) a synchrony of Venus and Mars conjunctions with the eclipses, (iii) conjunctions of Jupiter and Saturn repeated in a rare way, and (iv) a synchrony of synodic and sideric periods of Mercury with the tropical year. Based on our analysis, we find that the B&B correlation yields the best agreement with the astronomical phenomena observed by the Maya. Therefore we recommend to reject the GMT and support the B&B correlation.

On Robust Control of Fractional Order Plants: Invariant Phase Margin

2015 ◽  
Vol 10 (5) ◽  
Author(s):  
Mohammad Hossein Basiri ◽  
Mohammad Saleh Tavazoei
Keyword(s):  
Robust Control ◽  
Fractional Order ◽  
Phase Margin ◽  
Crossover Frequency ◽  
Large Uncertainty ◽  
Robust Controller ◽  
Numerical Examples

Recently, a robust controller has been proposed to be used in control of plants with large uncertainty in location of one of their poles. By using this controller, not only the phase margin and gain crossover frequency are adjustable for the nominal case but also the phase margin remains constant, notwithstanding the variations in location of the uncertain pole of the plant. In this paper, the tuning rule of the aforementioned controller is extended such that it can be applied in control of plants modeled by fractional order models. Numerical examples are provided to show the effectiveness of the tuned controller.

scholarly journals Estimating the Case Fatality Risk of COVID-19 using Cases from Outside China

2020 ◽  
Author(s):  
Nick Wilson ◽  
Amanda Kvalsvig ◽  
Lucy Telfar Barnard ◽  
Michael G Baker
Keyword(s):  
Intensive Care ◽  
Intensive Care Units ◽  
Meta Analysis ◽  
Case Fatality ◽  
Large Uncertainty ◽  
Icu Patients ◽  
Fatality Risk ◽  
Case Fatality Risk ◽  
Respiratory Conditions

AbstractThere is large uncertainty around the case fatality risk (CFR) for COVID-19 in China. Therefore, we considered symptomatic cases outside of China (countries/settings with 20+ cases) and the proportion who are in intensive care units (4.0%, 14/349 on 13 February 2020). Given what is known about CFRs for ICU patients with severe respiratory conditions from a meta-analysis, we estimated a CFR of 1.37% (95%CI: 0.57% to 3.22%) for COVID- 19 cases outside of China.

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