scholarly journals Long-Term Behavior of Dynamic Equilibria in Fluid Queuing Networks

2021 ◽  
Author(s):  
Roberto Cominetti ◽  
José Correa ◽  
Neil Olver

Steady State in Equilibrium for Flows over Time

Author(s):  
Minesh K. Patel ◽  
Georgios P. Balomenos

<p>The <span>long-term performance and safety of bridges is of paramount importance. Researchers have placed significant focus on the degradation and deterioration of bridge materials such as steel and concrete, but significantly less is known about the long-term behavior of bridge bearings. Uncertainty in the bearing behavior over time leads to challenges about when the bearings should be inspected and potentially replaced. However, bearing demands vary greatly based on the design of the bridge (e.g. differences in bridge material, girder type, span, height, and location). This paper finds trends in lifetime bearing demands from seismic, thermal, and traffic loading when the bridge design and location parameters are considered. These results can be used to identify which of the parameters have the greatest influence on the lifetime bearing demands which can then be used, in turn, to evaluate bearing long-term performance.</span></p>


Water Policy ◽  
2005 ◽  
Vol 7 (5) ◽  
pp. 469-483
Author(s):  
Tishya Chatterjee

In conditions of severe water-pollution and dormant community acceptance of accumulating environmental damage, the regulator's role goes beyond pollution prevention and more towards remediation and solutions based on the community's long-term expectations of economic benefits from clean water. This paper suggests a method to enable these benefits to become perceptible progressively, through participatory clean-up operations, supported by staggered pollution charges. It analyses the relevant literature on pollution prevention and applies a cost-based “willingness to pay” model, using primary basin-level data of total marginal costs. It develops a replicable demand-side approach imposing charge-standard targets over time in urban-industrial basins of developing countries.


Author(s):  
Halil Kaya ◽  
Gaurango Banerjee

The paper examines the Sarbanes-Oxley (2002) Acts immediate impact on board composition and characteristics as well as possible reversals in its impact over time. Effects on directors age and tenure are analyzed over the 2001-06 sample period. Female participation in corporate boards is also studied in the pre-SOX and post-SOX periods. The dual roles of directors in being a member of the board as well as serving as either CEO, CFO, Chairman, Co-Chair, Founder, or Lead Director of their respective companies is also examined. We observe a short-term impact of SOX on board compositions due to changes seen in board characteristics between 2001 (pre-SOX), and 2003-05 short-term period (post-SOX). Also, we observe a reversal of board characteristics in 2006 to pre-SOX levels implying that the effects of SOX on board composition were short-lived, and needs to be monitored over time to ensure adherence to corporate accountability guidelines over the long-term.


2021 ◽  
pp. 194016122110252
Author(s):  
Sebastián Valenzuela ◽  
Daniel Halpern ◽  
Felipe Araneda

Despite widespread concern, research on the consequences of misinformation on people's attitudes is surprisingly scant. To fill in this gap, the current study examines the long-term relationship between misinformation and trust in the news media. Based on the reinforcing spirals model, we analyzed data from a three-wave panel survey collected in Chile between 2017 and 2019. We found a weak, over-time relationship between misinformation and media skepticism. Specifically, initial beliefs on factually dubious information were negatively correlated with subsequent levels of trust in the news media. Lower trust in the media, in turn, was related over time to higher levels of misinformation. However, we found no evidence of a reverse, parallel process where media trust shielded users against misinformation, further reinforcing trust in the news media. The lack of evidence of a downward spiral suggests that the corrosive effects of misinformation on attitudes toward the news media are less serious than originally suggested. We close with a discussion of directions for future research.


2021 ◽  
pp. 089020702110173
Author(s):  
Nadin Beckmann ◽  
Damian P Birney ◽  
Amirali Minbashian ◽  
Jens F Beckmann

The study aimed to investigate the status of within-person state variability in neuroticism and conscientiousness as individual differences constructs by exploring their (a) temporal stability, (b) cross-context consistency, (c) empirical links to selected antecedents, and (d) empirical links to longer term trait variability. Employing a sample of professionals ( N = 346) from Australian organisations, personality state data together with situation appraisals were collected using experience sampling methodology in field and repeatedly in lab-like settings. Data on personality traits, cognitive ability, and motivational mindsets were collected at baseline and after two years. Contingent (situation contingencies) and non-contingent (relative SD) state variability indices were relatively stable over time and across contexts. Only a small number of predictive effects of state variability were observed, and these differed across contexts. Cognitive ability appeared to be associated with state variability under lab-like conditions. There was limited evidence of links between short-term state and long-term trait variability, except for a small effect for neuroticism. Some evidence of positive manifold was found for non-contingent variability. Systematic efforts are required to further elucidate the complex pattern of results regarding the antecedents, correlates and outcomes of individual differences in state variability.


2021 ◽  
Vol 13 (11) ◽  
pp. 6313
Author(s):  
Ramona Ciolac ◽  
Tiberiu Iancu ◽  
Ioan Brad ◽  
Tabita Adamov ◽  
Nicoleta Mateoc-Sîrb

The agritourism activity can be a characteristic reality of the present, considering rural area’s sustainability, being at the same time a business reality for rural entrepreneurs and a “must have” for rural communities that have tourism potential. It is a form of tourism, through which the tourist can receive a qualitative product at a reasonable price, but also a field that can ensure sustainable development over time, being at the same time environmentally friendly. The purpose of this scientific paper is to identify the aspects that make agritourism “a possible business reality of the moment”, for Romanian rural area’s sustainability. We take into account the following areas: Bran-Moieciu area—considered “the oldest” in terms of agritourism experience, and Apuseni Mountains area, with a great inclination and potential for this activity. The study conducted for these two areas is focused on several aspects: the degree of involvement in agritourism activities, considering the number of years and managerial experience, the analysis of the types of activities/experiences offered by agritourism structures, the identification of the main reasons/motivations for the orientation towards agritourism and the manner in which this field is perceived. Aspects related to the marketing-finance part of the agritourism business are also taken into account: customers, distribution channels, financial sources, shortcomings observed by agritourism business owners and possible action directions so as to improve the activity/agritourism product. Agritourism may be “a possible business reality of the moment” for the studied areas and not only, but in the future, the entrepreneur/farmer must be constantly updated because of the changing situations that appear on the market, be able to make sustainable decisions for his/her own business, which in the future will ensure its viability and obviously its long-term profitability and development, and in the same time rural area’s sustainability.


Author(s):  
Rebekah J. Nixon ◽  
Sascha H. Kranen ◽  
Anni Vanhatalo ◽  
Andrew M. Jones

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 .


2020 ◽  
Vol 31 (3) ◽  
pp. 453-460 ◽  
Author(s):  
Christina Halperin ◽  
Carolyn Freiwald ◽  
Gyles Iannone

AbstractThe Maya area has long been characterized as a mosaic of polities large and small, with cultural connections, linguistic dialects, ethnicities, and economic networks that shifted, expanded, and contracted over time. In this paper, we examine different ways of constructing boundaries. From physical demarcations in the landscape to habitual practices of interaction and affiliation, the lines that tied and divided were both unstable and multiple. We draw on definitions and theories from anthropology, history, and geography to review the concepts of borders, frontiers, and boundaries and their implications for the Maya area over the long term.


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