Statistical Approaches for Modeling Ice Sheet Interconnectivity

2020 ◽  
Author(s):  
Andrew Martinez ◽  
Luke Jackson ◽  
Felix Pretis ◽  
Katarina Juselius
Keyword(s):  
Ice Sheets ◽  
Sudden Loss ◽  
Sources Of Uncertainty ◽  
Long Run ◽  
Out Of Sample ◽  
Statistical Approaches ◽  
Ice Leads ◽  
The Stability ◽  
Over Time ◽  
Run Theory

<p>The greatest sources of uncertainty for future sea-level rise are the Greenland and Antarctic ice sheets. An important aspect of this uncertainty is the potential interconnectivity between them, which may amplify underlying instabilities in individual ice sheets. We explore these connections empirically by modelling the ice sheets as a cointegrated system. We consider two specications which allow the ice sheets to follow either an I(1) or an I(2) process in order to disentangle the long-run theory consistent relationships in the data. We examine the stability of these relationships over time both in and out of sample and eximine how a sudden loss of ice in Greenland propagates through the system. We show that a 1 Gigatonne loss of ice leads to a large and persistent loss of ice in West Arctica which is partially offset by an accumulation of ice in East Antarctica. Accounting for the long-run interactions between the ice sheets helps to improve our understanding of future instabilities and provides useful projections of the future paths of the ice sheets.</p>

On the Constancy of Hedonic Wine Price Coefficients over Time

2019 ◽  
Vol 14 (2) ◽  
pp. 182-207 ◽  
Author(s):  
Benoît Faye ◽  
Eric Le Fur
Keyword(s):  
Time Series ◽  
Literature Review ◽  
Time Series Data ◽  
Hedonic Model ◽  
Series Data ◽  
Extensive Literature ◽  
Long Run ◽  
The Stability ◽  
Over Time ◽  
Jel Classifications

AbstractThis article tests the stability of the main hedonic wine price coefficients over time. We draw on an extensive literature review to identify the most frequently used methodology and define a standard hedonic model. We estimate this model on monthly subsamples of a worldwide auction database of the most commonly exchanged fine wines. This provides, for each attribute, a monthly time series of hedonic coefficients time series data from 2003 to 2014. Using a multivariate autoregressive model, we then study the stability of these coefficients over time and test the existence of structural or cyclical changes related to fluctuations in general price levels. We find that most hedonic coefficients are variable and either exhibit structural or cyclical variations over time. These findings shed doubt on the relevance of both short- and long-run hedonic estimations. (JEL Classifications: C13, C22, D44, G11)

Sources of U.S. Economic Growth in a World of Ideas

2002 ◽  
Vol 92 (1) ◽  
pp. 220-239 ◽  
Author(s):  
Charles I Jones
Keyword(s):  
Educational Attainment ◽  
Population Growth ◽  
World Population ◽  
World Population Growth ◽  
Long Run ◽  
The Stability ◽  
Research Intensity ◽  
Constant Growth ◽  
The U.S ◽  
Over Time

Rising educational attainment and research intensity in recent decades suggest that the U.S. economy is far from its steady state. This paper develops a model reconciling these facts with the stability of U.S. growth rates. In the model, long-run growth arises from the worldwide discovery of ideas, which depends on population growth. Nevertheless, constant growth can temporarily proceed at a faster rate, provided research intensity and educational attainment rise steadily over time. Growth accounting reveals that these factors explain 80 percent of recent U.S. growth, with less than 20 percent coming from world population growth.

On the Robustness of Solution Strategy Classifications

2010 ◽  
Vol 31 (2) ◽  
pp. 68-73 ◽  
Author(s):  
María José Contreras ◽  
Víctor J. Rubio ◽  
Daniel Peña ◽  
José Santacreu
Keyword(s):  
Individual Differences ◽  
Study Strategies ◽  
Solution Strategy ◽  
Specific Test ◽  
Spatial Tasks ◽  
The Stability ◽  
Strategy Changes ◽  
Over Time

Individual differences in performance when solving spatial tasks can be partly explained by differences in the strategies used. Two main difficulties arise when studying such strategies: the identification of the strategy itself and the stability of the strategy over time. In the present study strategies were separated into three categories: segmented (analytic), holistic-feedback dependent, and holistic-planned, according to the procedure described by Peña, Contreras, Shih, and Santacreu (2008) . A group of individuals were evaluated twice on a 1-year test-retest basis. During the 1-year interval between tests, the participants were not able to prepare for the specific test used in this study or similar ones. It was found that 60% of the individuals kept the same strategy throughout the tests. When strategy changes did occur, they were usually due to a better strategy. These results prove the robustness of using strategy-based procedures for studying individual differences in spatial tasks.

On the Stability of Evaluative Conditioning Effects

2013 ◽  
Vol 44 (6) ◽  
pp. 380-389 ◽  
Author(s):  
Sabine Förderer ◽  
Christian Unkelbach
Keyword(s):  
Evaluative Conditioning ◽  
Indirect Measures ◽  
The Stability ◽  
Over Time

Evaluative conditioning (EC) refers to valence changes in neutral stimuli (CSs) through repeated pairing with liked or disliked stimuli (USs). The present study examined the stability of EC effects in the course of 1 week. We investigated how this stability depends on memory for US valence and US identity. We also investigated whether CSs evaluations occurring immediately after conditioning (i.e., evaluative consolidation) are necessary for stable EC effects. Participants showed stable EC effects on direct and indirect measures, independent of evaluations immediately after conditioning. EC effects depended on memory for US valence but not for US identity. And although memory decreased significantly over time, EC effects remained stable. These data suggest that evaluative consolidation is not necessary, and that conditioned preferences and attitudes might persist even when people do not remember the concrete source anymore.

scholarly journals Steady-state $$\dot{V}{\text{O}}_{2}$$ above MLSS: evidence that critical speed better represents maximal metabolic steady state in well-trained runners

2021 ◽  
Author(s):  
Rebekah J. Nixon ◽  
Sascha H. Kranen ◽  
Anni Vanhatalo ◽  
Andrew M. Jones
Keyword(s):  
Steady State ◽  
Critical Speed ◽  
Lactate Concentration ◽  
Practical Interest ◽  
Blood Lactate Concentration ◽  
Distance Runners ◽  
Severe Intensity ◽  
The Stability ◽  
Trained Runners ◽  
Over Time

AbstractThe metabolic boundary separating the heavy-intensity and severe-intensity exercise domains is of scientific and practical interest but there is controversy concerning whether the maximal lactate steady state (MLSS) or critical power (synonymous with critical speed, CS) better represents this boundary. We measured the running speeds at MLSS and CS and investigated their ability to discriminate speeds at which $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 was stable over time from speeds at which a steady-state $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 could not be established. Ten well-trained male distance runners completed 9–12 constant-speed treadmill tests, including 3–5 runs of up to 30-min duration for the assessment of MLSS and at least 4 runs performed to the limit of tolerance for assessment of CS. The running speeds at CS and MLSS were significantly different (16.4 ± 1.3 vs. 15.2 ± 0.9 km/h, respectively; P < 0.001). Blood lactate concentration was higher and increased with time at a speed 0.5 km/h higher than MLSS compared to MLSS (P < 0.01); however, pulmonary $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 did not change significantly between 10 and 30 min at either MLSS or MLSS + 0.5 km/h. In contrast, $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 increased significantly over time and reached $$\dot{V}{\text{O}}_{2\,\,\max }$$ V ˙ O 2 max at end-exercise at a speed ~ 0.4 km/h above CS (P < 0.05) but remained stable at a speed ~ 0.5 km/h below CS. The stability of $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 at a speed exceeding MLSS suggests that MLSS underestimates the maximal metabolic steady state. These results indicate that CS more closely represents the maximal metabolic steady state when the latter is appropriately defined according to the ability to stabilise pulmonary $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 .

scholarly journals Effect of Photoinitiator on Precursory Stability and Curing Depth of Thiol-Ene Clickable Gelatin

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1877
Author(s):  
Kai-Hung Yang ◽  
Gabriella Lindberg ◽  
Bram Soliman ◽  
Khoon Lim ◽  
Tim Woodfield ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Visible Light ◽  
Rheological Properties ◽  
Swelling Ratio ◽  
Sodium Persulfate ◽  
Photo Polymerization ◽  
Gelation Kinetics ◽  
The Stability ◽  
Over Time

Recent advances highlight the potential of photopolymerizable allylated gelatin (GelAGE) as a versatile hydrogel with highly tailorable properties. It is, however, unknown how different photoinitiating system affects the stability, gelation kinetics and curing depth of GelAGE. In this study, sol fraction, mass swelling ratio, mechanical properties, rheological properties, and curing depth were evaluated as a function of time with three photo-initiating systems: Irgacure 2959 (Ig2959; 320–500 nm), lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP; 320–500 nm), and ruthenium/sodium persulfate (Ru/SPS; 400–500 nm). Results demonstrated that GelAGE precursory solutions mixed with either Ig2959 or LAP remained stable over time while the Ru/SPS system enabled the onset of controllable redox polymerization without irradiation during pre-incubation. Photo-polymerization using the Ru/SPS system was significantly faster (<5 s) compared to both Ig2959 (70 s) and LAP (50 s). Plus, The Ru/SPS system was capable of polymerizing a thick construct (8.88 ± 0.94 mm), while Ig2959 (1.62 ± 0.49 mm) initiated hydrogels displayed poor penetration depth with LAP (7.38 ± 2.13 mm) in between. These results thus support the use of the visible light based Ru/SPS photo-initiator for constructs requiring rapid gelation and a good curing depth while Ig2959 or LAP can be applied for photo-polymerization of GelAGE materials requiring long-term incubation prior to application if UV is not a concern.

scholarly journals Competing Conventions with Costly Information Acquisition

Games ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 53
Author(s):  
Roberto Rozzi
Keyword(s):  
Information Acquisition ◽  
Evolutionary Model ◽  
Equilibrium Selection ◽  
The Other ◽  
Group Interactions ◽  
Social Coordination ◽  
Long Run ◽  
Stochastic Stability Analysis ◽  
The Stability ◽  
The Cost

We consider an evolutionary model of social coordination in a 2 × 2 game where two groups of players prefer to coordinate on different actions. Players can pay a cost to learn their opponent’s group: if they pay it, they can condition their actions concerning the groups. We assess the stability of outcomes in the long run using stochastic stability analysis. We find that three elements matter for the equilibrium selection: the group size, the strength of preferences, and the information’s cost. If the cost is too high, players never learn the group of their opponents in the long run. If one group is stronger in preferences for its favorite action than the other, or its size is sufficiently large compared to the other group, every player plays that group’s favorite action. If both groups are strong enough in preferences, or if none of the groups’ sizes is large enough, players play their favorite actions and miscoordinate in inter-group interactions. Lower levels of the cost favor coordination. Indeed, when the cost is low, in inside-group interactions, players always coordinate on their favorite action, while in inter-group interactions, they coordinate on the favorite action of the group that is stronger in preferences or large enough.

scholarly journals A Central Element of Europe’s Football Ecosystem: Competitive Intensity in the “Big Five”

2021 ◽  
Vol 13 (6) ◽  
pp. 3097
Author(s):  
Fabio Wagner ◽  
Holger Preuss ◽  
Thomas Könecke
Keyword(s):  
Big Five ◽  
Central Element ◽  
Quantitative Approach ◽  
Competitive Intensity ◽  
Entrepreneurial Ecosystems ◽  
Long Run ◽  
The Future ◽  
European Football ◽  
Over Time

This study perceives professional European football as one of the most relevant event-related entrepreneurial ecosystems (EEs) worldwide. It also identifies a healthy sporting competition in the five most popular European football leagues (Spain, England, Germany, Italy, and France), the “big five,” as a key pillar for the functioning of this ecosystem. By applying a quantitative approach, competitive intensity (CI) is measured for all big five leagues for 21 seasons (1998/99 to 2018/19). The chosen method does not only convey an overall indication of the competitive health of the entire league but also provides detailed information on the four important sub-competitions (championship race, qualification for Champions League or Europa League, and the fight against relegation). In all five leagues, seasonal CI tends to decrease over time, and especially over the last decade. The main reason is a decline in the intensity of the championship race while all other sub-competitions show relatively robust CI values. Overall, it can be concluded that the competitive health of the big five is intact, but the dwindling CI of the championship races can harm the EE of professional European football in the long run. Accordingly, it should be closely monitored in the future.

Braucht die EU einen flexibleren Stabilitätspakt?

2004 ◽  
Vol 53 (1) ◽  
Author(s):  
Carsten Hefeker ◽  
Friedrich Heinemann ◽  
Klaus F. Zimmermann
Keyword(s):  
Public Awareness ◽  
Time Lag ◽  
Fiscal Rules ◽  
External Control ◽  
Public Expenditures ◽  
Stability And Growth Pact ◽  
Consolidation Process ◽  
Growth Pact ◽  
Long Run ◽  
The Stability

AbstractIn his contribution Carsten Hefeker points out that most of the official arguments concerning the necessity of the Stability and Growth Pact are not convincing. Nevertheless, a mechanism that credibly avoids excessive debts and deficits is needed in most member states. It would be more useful, however, if such rules would focus on overall debt rather than on deficits. In addition, he advocates to create an external control for such fiscal rules, independent from the Commission and ECOFIN. He concludes that the Pact does not need to become more flexible, but more credible.Friedrich Heinemann states that much of the recent reform debate on the Stability Pact is based on a fundamental misconception: The Pact has not been established as a guiding tool for welfare - maximising politicians, but in order to limit detrimental incentives from fiscal short-sightedness. “Stupid” elements like the three-per-cent deficit ceiling have a clear and beneficial strategic function as boundary within the national budgetary process. Furthermore, simple rules are superior to smart ones in increasing the political costs of high deficits in terms of public awareness. The critique on the pact′s missing flexibility is correct mainly regarding its lose logical link to long-run sustainability. Increasing flexibility in a cyclical sense, however, is not a reform priority. Already today the Pact leaves sufficient leeway for responsible politicians. Instead, the reform focus must be on depoliticising the pact in the sense of limiting Council power in the deficit procedure. More flexibility must not come without depoliticising. He recommends that any reform should only be carried into effect with a significant time lag in order to limit the reputation damage which would be the consequence of any quick institutional response to the Pact′s recent crisis.In his paper Klaus F. Zimmermann argues that the Stability and Growth Pact (SGP) has been subject to criticism ever since its inception. He points out that it overlooks business cycle developments within the framework of the consolidation process; it adopts a too short-term view of the stabilisation target which is also hardly under control of policy-makers; and it deals with policy imperfections in a sub-optimal way. Therefore, a reform of the SGP is urgent. The author suggests that the rules must be handled more flexibly. In his opinion, a mediumterm budgetary target and a focus on public expenditures to tackle the pro-cyclical bias is needed. To restore credibility, the task of supervision should be transferred to an independent European institution.

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