| 1. |
- Alfeus, Anna, et al.
(författare)
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PM2.5 in Cape Town, South Africa: Chemical characterization and source apportionment using dispersion-normalised positive matrix factorization
- 2024
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Ingår i: Atmospheric Pollution Research. - 1309-1042. ; 15:3
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Tidskriftsartikel (refereegranskat)abstract
- Understanding fine particulate matter (PM2.5) composition and sources is beneficial to improving visibility, addressing climate change, and mitigating poor air quality and related public health effects. Source apportionment techniques have been instrumental in evaluating the impact of sources and secondary processes on the ambient PM2.5 concentrations in receptor areas. Positive Matrix Factorization (PMF) is now the most commonly used tool due to its ability to provide mixture resolution based on available PM2.5 compositional data. Sampling and analysis of PM2.5 was conducted in Cape Town, South Africa from April 2017 to April 2018. The resulting data were dispersion normalized to address the modifications of the source concentrations resulting from the varying dispersion conditions and thereby permit dispersion normalized PMF (DN-PMF) to be employed. DN-PMF quantified the 6 sources as 2-stroke vehicles/galvanizing industries (16.8%); soil/road dust (12.3%); sulphate/marine diesel (3.6%), traffic (15.7%), sea salt (21.8%), and heating/biomass burning/cooking (15.7%). In addition, air mass back trajectory analysis using the Hybrid Single Particle Lagrangian Trajectory (HYSPLIT) model identified long-range transport pathways to Cape Town. The HYSPLIT results showed air masses from the Atlantic SSW (6%), Atlantic SW (24%), Indian Ocean (31%), and Atlantic WSW (39%) influence air quality. The primary sources affected by the transport clusters were heating, 2-stroke vehicles/galvanizing, road and soil dust, and traffic emissions. These results show that reducing emissions from the local sources will improve air quality.
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| 2. |
- Baker, H. Kent, et al.
(författare)
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Payouts and stock ownership
- 2021
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Ingår i: Journal of Multinational Financial Management. - : Elsevier BV. - 1042-444X .- 1873-1309. ; 60
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Tidskriftsartikel (refereegranskat)abstract
- Using a unique Swedish database that records the ultimate stockholdings in public firms, we decompose stock ownership by domiciles using votes rather than cashflows. We then study the impact of variables related to the lifecycle theory of dividends and the catering theory of dividends. We also examine the propensity of firms to pay dividends and/or activate a stock buyback program. Univariate analysis reveals a positive association between a firm’s maturity and its likelihood to pay dividends. Logistic regression finds a positive relation between payouts and retained earnings to total assets. Foreign institutional investors are less likely to hold dividend-paying stocks than domestic institutional investors. The analysis finds no support for the catering theory of dividends. After controlling for stock ownership, our evidence is consistent with the lifecycle theory of dividends, which states that more mature firms are associated with dividends. It also supports the transaction cost hypothesis claiming that foreign investors face additional administrative costs when holding dividend-paying stocks.
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| 3. |
- Bergström, Clas, et al.
(författare)
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Price differentials between different classes of stocks: an empirical study on Chinese stock markets
- 2001
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Ingår i: Journal of multinational financial management. - : Elsevier B.V. - 1873-1309 .- 1042-444X. ; 11:4, s. 407-426
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the effect of strict segmentation on pricing in the context of the Chinese stock markets. The paper demonstrates that information asymmetry between foreign investors and domestic investors, liquidity effects, diversification effects, clientele bias, risk-free return differentials between foreign and domestic investors, and foreign exchange risks are significant factors in explaining discounts on shares that can only be owned by foreign investors.
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| 4. |
- Bidleman, Terry F, et al.
(författare)
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Chiral persistent organic pollutants as tracers of atmospheric sources and fate : review and prospects for investigating climate change influences
- 2012
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Ingår i: Atmospheric Pollution Research. - 1309-1042. ; 3:4, s. 371-382
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Tidskriftsartikel (refereegranskat)abstract
- Elimination of persistent organic pollutants (POPs) under national and international controls reduces “primary” emissions, but “secondary” emissions continue from residues deposited in soil, water, ice and vegetation during former years of high usage. Secondary sources are expected to dominate in the future, when POPs transport and accumulation will be controlled by air–surface exchange and the biogeochemical cycle of organic carbon. Climate change is likely to affect mobilization of POPs through, e.g., increased temperature, loss of ice cover in polar regions, melting glaciers and changes in soil and water microbiology which affect degradation and transformation. Chiral compounds offer advantages for following transport and fate pathways because of their ability to distinguish racemic (newly released or protected from microbial attack) and nonracemic (microbially altered) sources. Here we explain the rationale for this approach and suggest applications where chiral POPs could aid investigation of climate–mediated exchange and degradation processes. Examples include distinguishing agricultural vs. non–agricultural and recently used vs. residual pesticides, degradation and sequestration processes in soil, historical vs. recent atmospheric deposition, sources in arctic air and influence of ice cover on volatilization.
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| 5. |
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| 6. |
- Fatehi, Hesameddin, et al.
(författare)
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Effect of buoyancy on dispersion of reactive pollutants in urban canyons
- 2022
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Ingår i: Atmospheric Pollution Research. - : Elsevier BV. - 1309-1042. ; 13:8
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we aim to investigate the interplay between chemistry, flow dynamics and temperature using high fidelity computational fluid dynamics (CFD) models in an urban environment. A detailed numerical model based on large eddy simulation (LES) is developed considering the temperature and buoyancy effect and the non-equilibrium chemical processes. The model is used to study flow and reaction inside experimental and real-size street canyons. Street canyons are chosen for this study, as they represent the smallest unit of urban environments where detailed flow simulations combined with chemical reactions can be performed with high numerical accuracy. The effect of thermal driven flow is studied in reacting and non-reacting conditions to understand the role of buoyancy in accurately modeling pollutant reaction and dispersion. It is shown that buoyancy has a significant effect on the dynamics of the flow, by altering the main vortex structure inside the canyon and by increasing turbulent kinetic energy. It is also found that the chemical reactions strongly affect final concentrations of pollutants, which indicates the potential need for implementation of more advanced chemical models in future work. The importance of correct boundary conditions to accurately predict pollutant concentrations are discussed. Finally, by comparing the LES results with experimental field measurements in a real street canyon, the limitation of using periodic boundary conditions, as it is commonly used in the literature, is discussed. Moreover, it is shown that implementation of a variable photolysis rate is likely needed.
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| 7. |
- Graham, Michael, et al.
(författare)
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On Institutional Investors and Firm Performance : A Disaggregated View
- 2009
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Ingår i: Journal of Multinational Financial Management. - : Elsevier BV. - 1042-444X .- 1873-1309. ; 19:5, s. 370-394
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Tidskriftsartikel (refereegranskat)abstract
- We study the relationship between institutional ownership and firm performance in Finland. A systems approach is employed to investigate the potential two-way causality between firm performance and ownership structure. Three-stage least squares estimation technique is used to solve for the systems. The evidence suggests an endogeneity problem between firm performance and institutional ownership. However, the magnitude of the problem differs with respect to the concentration of ownership measure used. Our results show that a more equal distribution of the voting power among the largest institutional stakeholder may exert positive effects on firm performance. We also find a significant difference relating to firm performances and equity ownerships between the two classes of institutional investor. Consistent with the ownership structure in Finland, we find that a simple ownership concentration index does not influence firm performance.
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| 8. |
- Grundström, Maria, 1979, et al.
(författare)
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Influence of atmospheric circulation patterns on urban air quality during the winter
- 2015
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Ingår i: Atmospheric Pollution Research. - 1309-1042. ; 6:2, s. 278-285
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Tidskriftsartikel (refereegranskat)abstract
- Relationships between urban nitrogen dioxide (NO2) and atmospheric circulation at two spatial scales were studied for Southern Sweden. Lamb Weather Types (LWT) describe the circulation (scale: thousands of kilometers) including non–directional (cyclonic and anticyclonic) and directional types depending on the wind direction. LWTs with low wind speeds (anticyclonic, NW and N) were associated with strongly elevated [NO2], between 46–52% of the daily averages of NO2 exceeded the 60 μg m–3 air quality standard (AQS) when occurring during these LWTs. The lowest fractions of exceedances of NO2 AQS were generally observed for LWTs E, S, SW and W. A larger scale circulation (several thousands of kilometers) was represented by the North Atlantic Oscillation (NAO) affecting meteorology over middle and high latitudes in the Northern Hemisphere. While a negative NAO index (NAOI) favors stagnant high pressure weather over Northern Europe, a positive NAOI is often associated with windy conditions. High [NO2] was found to be frequent under negative NAOI. Additionally, larger fractions of exceedances of NO2 AQS were observed for the majority of LWTs occurring at negative NAOI. It’s concluded that both LWTs and NAOI had partly independent effects on the urban air quality in a North European city. These circulation indices can be useful tools for air pollution risk assessment and forecasting.
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| 9. |
- Gusev, Alexey, et al.
(författare)
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Intercontinental transport of persistent organic pollutants : a review of key findings and recommendations of the task force on hemispheric transport of air pollutants and directions for future research
- 2012
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Ingår i: Atmospheric Pollution Research. - 1309-1042. ; 3:4, s. 463-465
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Tidskriftsartikel (refereegranskat)abstract
- The Task Force on Hemispheric Transport of Air Pollution (TF HTAP) was established under the Convention on Long-range Transboundary Air Pollution (CLRTAP) to improve scientific understanding of the intercontinental transport of air pollutants and to deliver policy-relevant information on this issue. The first comprehensive assessment of POP intercontinental transport made by the TF HTAP was compiled in 2010 and published in 2011. The HTAP assessment was made possible by the contributions of a large network of experts in various national and international organizations and is intended to support further development of international policy and regulation of POPs under the frameworks of the UN ECE CLRTAP and the Stockholm Convention on POPs. By summarizing the outcome of past studies on POPs, the assessment highlights the evidence of POP intercontinental transport and the associated threat to human health and the environment. It presents the current state of knowledge on levels of POPs in the environment, emission inventories and projections, modeling of long-range transport and fate in various compartments, interactions with climate change, as well as harmful effects on human health and ecosystems. Two important outcomes of the HTAP 2010 assessment are the summary of key scientific and policy-relevant findings, and the recommendations for further work which include the need to a more fully developed integrated approach to the pollution assessment. In its next phase, which extends to 2015, the Task Force is planning to cooperate across different thematic areas of scientific activity on intercontinental transport of pollution, and exploit synergies of effort in cases where particulate matter (PM), ozone, mercury, and POPs share common sources. It is recognized that a fully integrated approach for building a scientific understanding of POPs in the environment should encompass measurements, modeling results, and emission estimates, and in addition it should more explicitly include assessment of ecosystem effects. (C) Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License.
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| 10. |
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| 11. |
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| 12. |
- Ivaschenko, Iryna
(författare)
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Asian flu or Wall Street virus? : tech and non-tech spillovers in the United States and Asia
- 2003
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Ingår i: Journal of Multinational Financial Management. - : Elsevier. - 1873-1309 .- 1042-444X. ; 13:4-5, s. 303-322
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Using TGARCH models, this paper finds that U.S. stock markets have been the major source of price and volatility spillovers to stock markets in the Asia-Pacific region during three different periods of the last decade: the pre-Long Tenn Capital Management crisis period, the "tech bubble" period, and the "stock market correction" period. Hong Kong SAR, Japan, and Singapore were also important sources of spillovers within the AsiaPacific region and, to a lesser degree, affected the United States during the "stock market correction" period. There is also evidence of structural breaks in the stock price and volatility dynamics induced during the "tech bubble" period.
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| 13. |
- Ivaschenko, Iryna
(författare)
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Coping with financial spillovers from the United States : the effect of U. S. corporate scandals on Canadian stock prices
- 2004
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Ingår i: Journal of Multinational Financial Management. - : Elsevier. - 1873-1309 .- 1042-444X. ; 14:4-5, s. 407-424
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper investigates the effect of U.S. corporate scandals on stock prices of Canadian firms listed in the United States. It finds that firms interlisted during the pre-Enron period enjoyed increases in equilibrium prices after the listing, while firms interlisted during the post-Enron period experienced declines in equilibrium prices, relative to a model-based benchmark. The paper offers several explanations of why firms listed post-Enron experienced negative gains from the listing. Moreover, analyzing the entire universe of Canadian firms, it finds that interlisted firms, regardless of their listing time, were perceived as increasingly risky by Canadian investors after Enron's bankruptcy.
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| 14. |
- Kang, Sang Hoon, et al.
(författare)
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Directional spillover effects between ASEAN and world stock markets
- 2019
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Ingår i: Journal of Multinational Financial Management. - : ELSEVIER. - 1042-444X .- 1873-1309. ; 52-53
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Tidskriftsartikel (refereegranskat)abstract
- We investigate dynamic spillovers between ASEAN-5 and world stock markets using a dynamic equicorrelation (DECO) model and the spillover index of Diebold and Yilmaz (2012)), which identifies net directional spillovers for each one of the markets. The DECO model uses more information to calculate dynamic correlations between each pair of returns than standard dynamic conditional correlation models, decreasing the estimation noise of the correlations. Directional spillovers from world stock markets to ASEAN-5 stock markets are higher than in the opposite direction. Besides, our results indicate heterogeneity among the ASEAN-5 stock markets in the degree of spillover to world markets over time. We verify an increase in both return and volatility spillovers during financial crises, confirming the intensity of information transmission during periods of turmoil. These findings help understand the economic channels through which the ASEAN-5 equity markets are connected, and have important implications for emerging and frontier markets. (C) 2019 Elsevier B.V. All rights reserved.
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| 15. |
- Kao, Xiaoxuan, et al.
(författare)
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The pressure of coal consumption on China's carbon dioxide emissions: A spatial and temporal perspective
- 2024
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Ingår i: Atmospheric Pollution Research. - : TURKISH NATL COMMITTEE AIR POLLUTION RES & CONTROL-TUNCAP. - 1309-1042. ; 15:8
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Tidskriftsartikel (refereegranskat)abstract
- As the world's largest coal consumer, China is facing the dual challenge of implementing strict coal reduction policies while heavily relying on coal. It is crucial to comprehend the pressures exerted on carbon dioxide emissions from coal consumption as China strives to transition towards a carbon-neutral era. This study defines and classifies the pressure of carbon dioxide emissions resulting from coal consumption, referred to as "carboncoal pressure", in 30 provinces (including municipalities and autonomous regions) from 1997 to 2019. This classification enriches the study of the pressure on carbon dioxide emissions by specific energy types. By calculating the centre of gravity of the carbon-coal pressure and its evolution trends, the spatial pattern of the carbon-coal pressure and the evolution characteristics of the centre of gravity of the pressure are revealed. The results demonstrate that, despite the continuous growth in total coal consumption and carbon dioxide emissions in China, the carbon-coal pressure index exhibits a decreasing trend in certain regions, with significant interregional differences. Most provinces fall into the high-pressure and higher-pressure categories. The number of high-pressure provinces has decreased by 33% from 18 to 8, while the number of low-pressure provinces has risen from 0 to 1, and both higher and medium pressure types have increased. The overall stress index decreases from 0.79 to 0.7. The pressure centre displays a similar spatial trend to the overall changes in coal consumption and carbon dioxide emissions centre, albeit with a smaller magnitude of change. Beijing stands out as the only province with low pressure.
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| 16. |
- Kravtsova, Victoria
(författare)
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Identifying patterns of outward foreign direct investments : Some empirical evidence
- 2010
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Ingår i: Journal of Multinational Financial Management. - : Elsevier BV. - 1042-444X .- 1873-1309. ; 20:1, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- This paper uses industry level panel data of all Austrian affiliates operating abroad during the period 1992-2005 to investigate the determinants of performance, as reflected by the number of affiliates, their productivity and returns on patents and licenses. The determinants of each performance indicator are found to be different. Moreover, the determinants vary further when the full dataset is disaggregated into manufacturing and service sectors.
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| 17. |
- Naghibi, Seyed Amir, et al.
(författare)
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Spatiotemporal variability of dust storm source susceptibility during wet and dry periods: The Tigris-Euphrates River Basin
- 2024
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Ingår i: Atmospheric Pollution Research. - 1309-1042. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- This study develops a framework for spatiotemporal modeling of dust storm source susceptibility in a critical case study, the Tigris-Euphrates River Basin, as a significant source of dust storms in the Middle East. The study period was divided into four periods, 2000–2004 (hydrological dry year), 2005–2007 (hydrological wet year), 2008–2012 (hydrological dry year), and 2013–2021 (hydrological wet year) representing hydrological conditions in the study area. Initially, visual interpretations of true color composites of the MODIS satellite images were conducted to spot dust storm sources in the studied periods. Topographical, hydrological, soil texture, and vegetation health datasets were prepared to model dust storm source susceptibility in each period. The random forest algorithm was implemented on the four study periods’ datasets. For each period, 70% of dust and non-dust storm sources and conditioning factors were used for training the models. The models were then validated using the validation datasets (remaining 30%), and the importance of the variables was determined for each study period. In the 2008–2012 period, experiencing an extensive drought in the region, a higher number of dust storm sources were detected, and 383 locations (pixels) in the area were considered highly susceptible to dust storm sources. In all study periods, as well as in the ensemble model (integrating the results of four study periods into one overall model), high susceptibility to dust storms was detected in areas where lakes and marshlands had dried up due to climate factors, inappropriate water management strategies, and land use policies. The results also depicted that elevation, wind speed, precipitation, vegetation coverage, slope degree, distance from rivers, and soil texture had high impacts on the susceptibility of land to be a dust storm source.
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| 18. |
- Nordén, Lars
(författare)
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Asymmetric Option Price Distribution and Bid-Ask Quotes : Consequences for Implied Volatility Smiles
- 2003
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Ingår i: Journal of Multinational Financial Management. - 1042-444X .- 1873-1309. ; 13, s. 423-441
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Tidskriftsartikel (refereegranskat)abstract
- This study presents a model for estimating the asymmetry of option values with respect to option bid-ask spreads. The model does not require knowledge of the actual option value to evaluate the asymmetry. Using data from the Swedish equity options market, several interesting results emerge. First, there is evidence of asymmetry in call and put values, where values are closer to bid than to ask quotes. Second, in- and out-of-the-money calls and puts show a higher degree of asymmetry than at-the-money options. Third, taking asymmetry into account in the estimation of option-implied volatility, produces a less pronounced volatility smile.
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| 19. |
- Nordén, Lars
(författare)
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Hedging of American Equity Options : Do Call and Put Option Prices Always Move in the Direction as Predicted by the Movement in the Underlying Stock Price
- 2001
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Ingår i: Journal of Multinational Financial Management. - 1042-444X .- 1873-1309. ; 11:4-5, s. 321-340
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Tidskriftsartikel (refereegranskat)abstract
- Using daily Swedish equity options data, an empirical analysis of some basic textbook properties for American options is performed. Several violations of these properties are found; call and put prices often move in the “wrong” direction compared to the stock price, call and put prices sometimes also increase or decrease simultaneously and option price changes are often larger than corresponding stock price changes. The hedging performance of the American options is evaluated by constructing delta-neutral and delta-vega-neutral portfolios. The empirical performance of these strategies is sometimes bad. Indeed, violation occurrences make hedging a rather risky business.
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| 20. |
- Nordén, Lars, et al.
(författare)
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The Early Exercise Premium in American Put Option Prices
- 2000
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Ingår i: Journal of Multinational Financial Management. - 1042-444X .- 1873-1309. ; 10, s. 461-479
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Tidskriftsartikel (refereegranskat)abstract
- This study estimates the value of the early exercise premium in American put option prices using Swedish equity options data. The value of the premium is found as the deviation of the American put price from European put-call parity, and in addition a theoretical estimate of the premium is computed. The empirically found premium is also used in a modified version of the control variate approach to value American puts. The results indicate a substantial value of the early exercise premium, where the premium derived from put-call parity is higher than the theoretical premium. The premium also increases with moneyness and time left to expiration, while the effect of interest rate and volatility depends on the moneyness of the option. The modified control variate technique works reasonably well relative the theoretical models. In particular, for deep in-the-money options, this technique is superior.
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| 21. |
- Oxelheim, Lars, et al.
(författare)
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On the Static Efficiency of Secondary Bond Markets
- 2005
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Ingår i: Journal of Multinational Financial Management. - : Elsevier BV. - 1873-1309 .- 1042-444X. ; 15:2, s. 117-135
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Tidskriftsartikel (refereegranskat)abstract
- The major strand of finance literature understands market efficiency through the market's ability to process information into prices. Another strand of literature refers to the economists’ usual sense of the word, i.e., that markets ensure that resources are allocated to their most profitable expected use, and provide services at the lowest cost. This paper, deploying the second definition, suggests a concept of static efficiency, and claims this can also be seen as a measure of market quality. The paper develops a measure of qualitative static efficiency for bond markets built on four indicators: transparency, number of maturities and issuers, spread, and liquidity. Indicators of market quality should be easily accessible, and permit international and inter-temporal comparison. Using Nordic markets as case studies, we show that these markets became more efficient during the 1990's, but that transparency of efficiency remains a problem. A number of measurement problems with the static efficiency indicators are discussed, as well as interdependence issues. The paper concludes with comments on future applications of the static efficiency measure.
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| 22. |
- Rahimi, Mostafa, et al.
(författare)
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A novel approach for brake emission estimation based on traffic microsimulation, vehicle system dynamics, and machine learning modeling
- 2023
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Ingår i: Atmospheric Pollution Research. - 1309-1042. ; 14:10
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Tidskriftsartikel (refereegranskat)abstract
- Brake wear is known as the primary source of traffic-related non-exhaust particle generation. Its generation rate is influenced by parameters at different levels: subsystem (type of brakes, pads, materials, etc.), system (vehicles' dynamics, driving style etc.) and suprasystem (road geometries, traffic parameters, etc.). At the subsystem level, we proposed a neural network brake emission modeling, trained and validated through emission data collected from a reduced-scale dynamometer. At the system level, a model of a car dynamics was developed to calculate the wheels’ brake torques and angular velocities. At the suprasystem level, the traffic behavior in a sensitive urban area was characterized experimentally and simulated in a traffic microsimulation software. The vehicle traffic-based records were used to calculate the vehicle dynamic quantities, converted into brake emission through the neural network. To examine the overall traffic impacts on brake emission, the total particle number (PN) and total particle mass were estimated regarding the route choice in the sensitive area and in the whole transportation network. The findings of this study showed significant generation rate of brake emissions (in terms of mass and number) around congested areas (in the order of 10e9 #/s). The brake emission estimation in a real area provides fundamental information to the decision-makers to better insight into the rate of non-exhaust emissions generation.
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| 23. |
- Shatalov, Victor, et al.
(författare)
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Tracing the origin of dioxins in Baltic air using an atmospheric modeling approach
- 2012
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Ingår i: Atmospheric Pollution Research. - 1309-1042. ; 3:4, s. 408-416
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Tidskriftsartikel (refereegranskat)abstract
- Previous work has concluded that the sources of dioxins to the Baltic Sea are dominated by atmospheric deposition. Here, we investigate whether current emission estimates can explain Baltic air levels and deposition fluxes of four selected 2,3,7,8-substituted PCDD/F congeners using an atmospheric modeling approach. The EMEP (European Monitoring and Evaluation Programme) database of emissions for dioxins was used to provide inputs to the selected model (MSCE-POP model) and model predicted levels were compared with measurements of dioxins in air and deposition fluxes at three monitoring stations in Sweden. The model underestimated air concentrations between a factor of 5 and 30, with the level of agreement depending on congener, monitoring station and, importantly, with the compass sector from which the contaminated air mass had arrived. Additional model simulations were undertaken in which emissions were enlarged in some selected areas to optimize agreement between model predictions and measurements. A novel emission adjustment approach is used in an attempt to identify source regions where emissions were in error. The emission adjustment approach improved the agreement between model predictions and measurements for 60% of the measurements within a factor of 3 of model predicted concentrations. However, the agreement was still relatively poor when air masses originated from the SSE and SSW. The model adjustment procedure gives an indication of the magnitude of error in exiting emission estimates, but due to the poor quality of existing emission databases and few quality air monitoring data it is not currently possible to use the emission adjustment approach to accurately identify source regions of error. The approach presented here is promising, however, and could be applied to other substances where better emission and monitoring data are available. (C) Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License.
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| 24. |
- Sjö, Bo, et al.
(författare)
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Market segmentation and information diffusionin China’s stock markets
- 2000
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Ingår i: Journal of Multinational Financial Management. - 1042-444X .- 1873-1309. ; 10:3-4, s. 421-438
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Tidskriftsartikel (refereegranskat)abstract
- This study analyses the information diffusion between Chinese A shares (restricted todomestic investors) and B shares (restricted to foreign investors). The results show that thereis an important long-run information diffusion between A and B shares. In the Shanghaistock market, information flows from foreign to domestic investors. However, in the smallerand less liquid Shenzhen stock market, the information diffusion goes in the opposite way.The direction of the information diffusion is determined by the choice of stock exchange
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| 25. |
- Tiwari, Suresh, et al.
(författare)
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Assessment of PM2.5 and PM10 over Guwahati in Brahmaputra River Valley : Temporal evolution, source apportionment and meteorological dependence
- 2017
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Ingår i: Atmospheric Pollution Research. - : Elsevier BV. - 1309-1042. ; 8:1, s. 13-28
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Tidskriftsartikel (refereegranskat)abstract
- Temporal evolution, source apportionment and transport pathways of particulate matter (PM2.5 and PM10) are analysed over Guwahati, located in the Brahmaputra River Valley (BRV), as a function of meteorological dynamics. During the study period (July 2013-June 2014), the mean PM2.5 and PM10 mass concentrations were found to be 52 +/- 37 and 91 +/- 60 mu g m (-3), respectively, both exhibiting higher concentrations during DecembereMarch and very low during summer. The annual mean ratio of PM2.5/ PM10 was 0.57 +/- 0.11, varying from 0.24 to 0.86, suggesting dominance of anthropogenic vs natural emissions during winter and spring, respectively. Diurnal variation reveals higher PM concentrations during morning (similar to 9: 00 local time (LT)) and evening (similar to 23: 00 LT) and lowest around similar to 14: 00 to 17: 00 LT due to influence of dilution processes and higher mixing-layer height over the region. Bivariate plots and Conditional Bivariate Probability Function (CBPF) analysis showed that the highest PM2.5 and PM10 concentrations are mostly associated with weak northwestern winds (< 1.5 ms (- 1)) in all seasons except spring, when the highest PM10 are for southwestern winds above 4-6 ms(- 1), indicating dust transport from SW Asia. Analysis reveals that the local emissions, transported aerosols, along with seasonallychanged air masses, meteorology and boundary-layer dynamics control the concentrations, evolution and fractions of PM over BRV. The turbid air masses transported over Guwahati mostly from western and southwestern directions contribute to higher PM concentrations, either carrying anthropogenic pollution from Indo-Gangetic Plains or locally and LRT dust from BRV and western India, respectively.
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| 26. |
- Uddin, Gazi Salah, et al.
(författare)
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The impact of financial and economic factors on Islamic mutual fund performance: Evidence from multiple fund categories
- 2019
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Ingår i: Journal of Multinational Financial Management. - : ELSEVIER. - 1042-444X .- 1873-1309. ; 52-53
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Tidskriftsartikel (refereegranskat)abstract
- We examine the influence of financial, economic, and seasonal factors on the performance of international equity, fixed income, cash, and balanced Islamic mutual funds. We analyze monthly mutual fund return observations on 106 funds over 1997-2019 to investigate exposure to global developed Fama and French {1993, 2015) factors for equity and balanced funds, the three factors of Huij and Derwall {2008] for cash and bond funds, and monthly seasonal effects. Seasonal effects are insignificant in balanced, equity, and cash funds. The Fama and French factors significantly affect the performance of equity and balanced funds, whereas the three factors of Huij and Derwall are important in explaining the performance of cash and fixed income funds for almost over the whole year. Our findings suggest that investors should not be concerned about a potential seasonal effect due to the Ramadan period. (C) 2019 Elsevier B.V. All rights reserved.
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| 27. |
- Wang, Yuxuan, et al.
(författare)
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A deep learning approach to real-time CO concentration prediction at signalized intersection
- 2020
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Ingår i: Atmospheric Pollution Research. - : Elsevier BV. - 1309-1042. ; 11:8, s. 1370-1378
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Tidskriftsartikel (refereegranskat)abstract
- Vehicle exhaust emissions at signalized intersections are the essential source of traffic-related pollution to pedestrians. Therefore, it is critical to predicting traffic emissions, especially the hazardous CO gas, with practical and accurate methods. However, the CO emission and concentration at crosswalks can be influenced by the complex traffic conditions in a complicated way, making the prediction of CO concentration a challenging task for traditional statistical models. To this end, a hybrid machine learning framework is proposed in this study to investigate the concentration of CO emissions at pedestrian crosswalks. The proposed method firstly ranks key influencing factors with a random forest approach. Then a prediction model with Multi-Variate Long Short-Term Memory (LSTM) neural networks based on the selected factors is developed. Data is collected at the field intersection for model training and validation. The autoregressive integrated moving average (ARIMA), support vector machines (SVM), radial basis functions network (RBFN), nonlinear vector autoregressive (VAR) and gated recurrent unit ( GRU) neural network are selected as the benchmark models to verify the performance of the proposed model. The Root Mean Square Errors (RMSE), Mean Absolute Error (MAE) and R square are calculated to evaluate the performance of models comprehensively. The results indicated that the proposed model overwhelms the benchmark models in terms of prediction accuracy.
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| 28. |
- Woehrnschimmel, Henry, et al.
(författare)
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Global multimedia source-receptor relationships for persistent organic pollutants during use and after phase-out
- 2012
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Ingår i: Atmospheric Pollution Research. - 1309-1042. ; 3:4, s. 392-398
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Tidskriftsartikel (refereegranskat)abstract
- Chemicals that are persistent in the atmosphere can be transported long distances and across international boundaries. Therefore, information about the fraction of local versus imported air pollution is required to formulate regulations aimed at controlling pollutant levels. The objective of this work is to illustrate the capabilities of a dynamic global-scale multimedia model to calculate source-receptor relationships for persistent organic pollutants that cycle between air, water, soil and vegetation in the global environment. As exemplary case studies, we present model calculations of time-evolving source-receptor relationships for PCB28, PCB153, alpha-HCH and beta-HCH over the duration of their usage, phase-out and a post-ban period. Our analysis is geographically explicit, and elucidates the role of primary versus secondary sources in controlling the levels of air pollution. Our case studies consider source-receptor relationships between the four regions defined by the Convention on Long-range Transboundary Air Pollution Task Force on Hemispheric Transport of Air Pollution, as well as the Arctic as a remote receptor region. We find source-receptor relationships that are highly variable over time, and between different regions and chemicals. Air pollution by PCBs in North America and Europe is consistently dominated by local emissions, whereas in East-and South-Asia extra-regional sources are sometimes major contributors. Emissions of alpha-HCH peak at different times in the four regions, which leads to a phase of high self-pollution in each region, and periods when pollution enters mainly from outside. Compared to alpha-HCH, air pollution with the less volatile and more persistent beta-HCH is more strongly determined by secondary emissions near source areas throughout its use history. PCB concentrations in Arctic air are dominated by emissions transported from North America and Europe from 1930 to 2080, whereas for HCHs each of the source regions contributes a high share at some point between 1950 and 2050. (C) Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License.
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| 29. |
- Zalakeviciute, R., et al.
(författare)
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Chemical characterization of urban PM10 in the Tropical Andes
- 2019
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Ingår i: Atmospheric Pollution Research. - : Elsevier BV. - 1309-1042. ; 11:2, s. 343-356
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Tidskriftsartikel (refereegranskat)abstract
- Complex inhalable particles have become one of the main causes to trigger health problems worldwide. While the level of concern depends on the chemical composition of these particles, some regions are poorly studied, particularly, the Andes. In this work, the chemical characterization of atmospheric PM10 filter samples, collected between January and October of 2017, was carried out for the first time in the world's highest capital, Quito, Ecuador. This study investigates PM10 relation with meteorological variables and criteria pollutants. Average PM10 concentrations ranged from 24.9 μg m−3 to 26.2 μg m−3, with some alarming peaks during the episodes of fires and New Year's celebration. The major elements at study sites were Ca, Na, S, Mg, P, K, Fe, Si and Al, while the major water-soluble ion was SO42−. Meteorology plays an important role at this complex terrain city. Factor analysis showed natural dust and soil resuspension as the main source of particulate matter. Moreover, two less urbanized sites showed evidence of industrial activities or airport emissions, while the central city site showed a very strong signal of traffic-related pollution. These results are compared with representative cities around the world. As is the case in developing countries, low-quality diesel fuel is recognized for emitting large amounts of heavy metals, resulting in higher levels of those tracers in traffic flow areas. This work demonstrates the problems facing a midsize city, such as the lack of stricter regulations and, thus compromised air quality. This may imply serious respiratory and cardiovascular health effects.
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