Journal articles on the topic 'Global diffusion mechanisms'
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Park, Nara. "Global Environment and Local Governments: Global Norms, Policy Adoption, and Local Diffusion." Lex localis - Journal of Local Self-Government 19, no. 2 (April 29, 2021): 279–303. http://dx.doi.org/10.4335/19.2.279-303(2021).
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This article investigates a central question in modern organization theory, how organizations adapt to environmental changes by examining the diffusion of environmental ordinances among Korean local governments, 1995 to 2016. There are two waves in the diffusion; ‘Environment Basic Ordinance (1996-2007)’ and ‘Green Growth Ordinance (2010-2013).’ We argue that Korean local governments have increasingly become autonomous and accountable actors that respond to diversified stimulus from surrounding environments, while also concerning about their own needs and capacity. Hence, in adopting ‘Green Growth Ordinances,’ competitively adopted in the 2010s, Korean local governments considered more factors than they had done for ‘Environment Basic Ordinances.’ Employing event history analysis, we find empirical support for this argument. By comparing the diffusion pattern of the two environmental ordinances, this paper traces changing mechanisms of local environmental governance as well as policy diffusion among Korean local governments.
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Zhuang, Jun, and Lei Liu. "Global study of mechanisms for adatom diffusion on metal fcc(100) surfaces." Physical Review B 59, no. 20 (May 15, 1999): 13278–84. http://dx.doi.org/10.1103/physrevb.59.13278.
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Piecuch, Christopher G., and Rui M. Ponte. "Mechanisms of Global-Mean Steric Sea Level Change." Journal of Climate 27, no. 2 (January 15, 2014): 824–34. http://dx.doi.org/10.1175/jcli-d-13-00373.1.
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Abstract Global-mean sea level change partly reflects volumetric expansion of the oceans because of density change, otherwise known as global-mean steric sea level change. Owing to nonlinearities in the equation of state of seawater, the nature of processes contributing to recent observed global-mean steric sea level changes has not been well understood. Using a data-constrained ocean state estimate, global-mean steric sea level change over 1993–2003 is revisited, and contributions from ocean transports and surface exchanges are quantified using closed potential temperature and salinity budgets. Analyses demonstrate that estimated decadal global-mean steric sea level change results mainly from a slight, time-mean imbalance between atmospheric forcing and ocean transports over the integration period: surface heat and freshwater exchanges produce a trend in global-mean steric sea level that is mainly offset by the redistribution of potential temperature and salinity through small-scale diffusion and large-scale advection. A set of numerical experiments demonstrates that global-mean steric sea level changes simulated by ocean general circulation models are sensitive to the regional distribution of ocean heat and freshwater content changes.
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Lee, Mei-Man, A. J. George Nurser, A. C. Coward, and B. A. de Cuevas. "Eddy Advective and Diffusive Transports of Heat and Salt in the Southern Ocean." Journal of Physical Oceanography 37, no. 5 (May 1, 2007): 1376–93. http://dx.doi.org/10.1175/jpo3057.1.
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Abstract There are two distinct mechanisms by which eddies provide systematic transport of tracer on isopycnals: the advective transport, associated with the slumping of isopycnals, and the diffusive transport, associated with down-gradient diffusion. Depending on the large-scale tracer distribution, eddy advective transport has either the same direction as or opposite direction to eddy diffusive transport. As a consequence, eddy advection and eddy diffusion can reinforce each other for some tracers but oppose each other for other tracers. Using scaling analysis, it is argued that the relative directions of eddy advective and diffusive transports can be determined simply from the relative slopes of tracers and isopycnals. An eddy-resolving (1/12°) global ocean model is used to illustrate the two eddy transport mechanisms for temperature and salinity in the Southern Ocean. Applications to other tracers, such as oxygen, are discussed. The diagnosed eddy diffusivity for temperature (and salinity) is found to be considerably different from the eddy diffusivity for eddy advective transport velocity.
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Chen, Lei, and Ahmed F. Ghoniem. "Modeling CO2Chemical Effects on CO Formation in Oxy-Fuel Diffusion Flames Using Detailed, Quasi-Global, and Global Reaction Mechanisms." Combustion Science and Technology 186, no. 7 (May 28, 2014): 829–48. http://dx.doi.org/10.1080/00102202.2014.883384.
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Gleditsch, Kristian S., and Mauricio Rivera. "The Diffusion of Nonviolent Campaigns." Journal of Conflict Resolution 61, no. 5 (September 2, 2015): 1120–45. http://dx.doi.org/10.1177/0022002715603101.
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Existing research has uncovered strong geographical clustering in civil war and a variety of diffusion mechanisms through which violence in one country can increase the risk of outbreaks in other countries. Popular coverage of nonviolent protest often emphasizes regional waves like the 1989 revolutions in Eastern Europe and the Arab Spring. However, most research on nonviolence focuses only on features within countries affecting motivation and opportunities, and we know little about the possible role of diffusion and transnational factors. We detail how nonviolent campaigns in other states can increase nonviolent mobilization and direct action, highlighting important differences in the likely actors for violent and nonviolent direct action and the relevant diffusion mechanisms. We find strong empirical evidence for diffusion in nonviolent campaigns. The effects are largely confined to campaigns in neighboring countries, and there is little evidence of global diffusion. The potential diffusion effects are also specific to whether dissent is violent and nonviolent rather than general political instability. Moreover, we find that the effects of neighboring campaigns on nonviolent direct action apply only in cases with plausible motivation for contesting the government, and the effects are stronger when the regional environment can help expand opportunities for organizing dissent.
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Peng, Peng, Christophe Claramunt, Shifen Cheng, and Feng Lu. "How Does a Port Build Influence? Diffusion Patterns in Global Oil Transportation." Sensors 22, no. 22 (November 8, 2022): 8595. http://dx.doi.org/10.3390/s22228595.
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Ports play a critical role in the global oil trade market, and those with significant influence have an implicit advantage in global oil transportation. In order to offer a thorough understanding of port influences, the research presented in this paper analyzes the evolution of the dominance mechanisms underlying port influence diffusion. Our study introduces a port influence diffusion model to outline global oil transport patterns. It examines the direct and indirect influence of ports using worldwide vessel trajectory data from 2009 to 2016. Port influences are modelled via diffusion patterns and the resulting ports influenced. The results of the case study applied to specific ports show different patterns and influence evolutions. Four main port influence trends are identified. The first one is that ports that have a strong direct influence over their neighboring ports materialize a directly influenced area. Second, geographical distance still plays an important role in the whole port influence patterns. Third, it clearly appears that, the higher the number of directly influenced ports, the higher the probability of having an influence pattern, as revealed by the diffusion process. The peculiarity of this approach is that, in contrast to previous studies, global maritime trade is analyzed in terms of direct and indirect influences and according to oil trade flows.
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Kim, Dongwook. "International Nongovernmental Organizations and the Global Diffusion of National Human Rights Institutions." International Organization 67, no. 3 (July 2013): 505–39. http://dx.doi.org/10.1017/s0020818313000131.
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AbstractDuring the past three decades national human rights institutions (NHRIs) have spread to more than one hundred United Nations (UN) member states and become key to human rights enforcement and democratic accountability. Given that NHRIs can take on a life of their own even under adverse conditions, why do governments in the developing world create permanent, independent national bodies with statutory powers to promote and protect human rights? Human rights international nongovernmental organizations (INGOs) are crucial for global diffusion. They empower local actors and influence governments in favor of NHRI adoption by mediating the human rights and NHRI discourses and mobilizing shame internationally. An event history analysis offers robust evidence that controlling for the UN, regional organizations, and other rival factors, human rights INGOs have systematic positive effects on diffusion. The case studies of South Korea and Malaysia provide process-tracing evidence that the hypothesized causal mechanisms are operative.
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BROWN, GARRETT WALLACE. "Norm diffusion and health system strengthening: The persistent relevance of national leadership in global health governance." Review of International Studies 40, no. 5 (November 25, 2014): 877–96. http://dx.doi.org/10.1017/s0260210514000333.
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AbstractAcademics and policymakers often argue that global health policy greatly affects and influences national health systems because these policies transfer and implant ‘best practice’ norms and accountability techniques into local health systems. On the whole these arguments about the ‘diffusion of norms’ have merit since there is considerable evidence to suggest the existence of a positive correlation between global norms and national behaviour. Nevertheless, this article argues that traditional analytical frameworks to explain norm diffusion underplay the fact that norms are significantly ‘glocalised’ by national actors and further discount the role that national leadership plays in strengthening health systems. In response, this article presents a ten-year comparative paired study of the participatory governance mechanisms of the South African health system and its health strengthening measures. In doing so, the role of the national government in their relations with the Global Fund to Fight AIDS, Tuberculosis, and Malaria (GFATM) will be examined and how key ‘partnership’ norms were amalgamated into health governance mechanisms. It will be argued that although global policy plays an important guiding role, health norms are never transcribed straightforwardly and a central element to successful health governance remains vested in the nation and the leadership role it exerts.
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Simonsen, S. B., S. J. Johnsen, T. J. Popp, B. M. Vinther, V. Gkinis, and H. C. Steen-Larsen. "Past surface temperatures at the NorthGRIP drill site from the difference in firn diffusion of water isotopes." Climate of the Past 7, no. 4 (December 2, 2011): 1327–35. http://dx.doi.org/10.5194/cp-7-1327-2011.
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Abstract. A new ice core paleothermometer is introduced based on the temperature dependent diffusion of the stable water isotopes in the firn. A new parameter called differential diffusion length is defined as the difference between the diffusion length of the two stable water isotopologues 2H1H16O and 1H218O. A model treatment of the diffusion process of the firn and the ice is presented along with a method of retrieving the diffusion signal from the ice core record of water isotopes using spectral methods. The model shows how the diffusion process is highly dependent on the inter-annual variations in the surface temperatures. It results in a diffusion length longer than if the firn was isothermal. The longer diffusion length can be explained by the strong nonlinearly behaviour of the saturation pressure over ice in the range of the surface temperature fluctuations. The method has been tested on δ18O and δD measurements, spanning the transition from the last glacial to the holocene, from the NorthGRIP ice core. The surface temperature reconstruction based on the differential diffusion resembles other temperature reconstructions for the NorthGRIP ice core. However, the Allerød warming is seen to be significantly warmer than observed in other ice core based temperature reconstructions. The mechanisms behind this behaviour are not fully understood. The method shows the need of an expansion of high resolution stable water isotope datasets from ice cores. However, the new ice core paleothermometer presented here will give valuable insight into past climate, through the physical process of isotope diffusion in the firn column of ice sheets.
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Simonsen, S. B., S. J. Johnsen, T. J. Popp, B. M. Vinther, V. Gkinis, and H. C. Steen-Larsen. "Past surface temperatures at the NorthGRIP drill site from the difference in firn diffusion of water isotopes." Climate of the Past Discussions 7, no. 2 (March 2, 2011): 921–42. http://dx.doi.org/10.5194/cpd-7-921-2011.
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Abstract. A new ice core paleothermometer is introduced based on the temperature dependent diffusion of the stable water isotopes in the firn. A new parameter called differential diffusion length is defined as the difference between the diffusion length of the two stable water isotopes 18O and deuterium. A model treatment of the diffusion process of the firn and the ice is presented along with a method of retrieving the diffusion signal from the ice core record of water isotopes using spectral methods. The model shows how the diffusion process is highly dependent on the inter-annual variations in the surface temperatures resulting in a longer diffusion length than by assuming an isothermal firn. The longer diffusion length can be explained by the strong non-linearly behavior of the saturation pressure over ice in the range of the surface temperature fluctuations. The method has been tested on δ18O and δD measurements, spanning the transition from the last glacial to the holocene, from the NorthGRIP ice core. The surface temperature reconstruction based on the differential diffusion resembles other temperature reconstructions for the NorthGRIP ice core. However, the Allerød warming is seen to be significantly warmer than observed in other ice core based temperature reconstructions. The mechanisms behind this behavior are not fully understood. The method shows the need of an expansion of high resolution stable water isotopes data sets from ice cores. However, the new ice core paleothermometer presented here will give valuable insight in past climate, through the physical process of isotope diffusion in the firn column of ice sheets.
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Lee, Chengpang. "The Forgotten Bonds: A Coevolutionary Framework on the Diffusion of Tzu Chi in Four Southeast Asian Countries." American Behavioral Scientist 64, no. 10 (August 8, 2020): 1471–84. http://dx.doi.org/10.1177/0002764220947776.
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The literature on the diffusion of new religion is strongly influenced by the voluntaristic paradigm that highlights the agency of individual migrants. This article examines and compares the diffusion process and outcome of Tzu Chi (Buddhist Compassion Relief Tzu Chi Association) in four Southeast Asian countries—Malaysia, Indonesia, Singapore, and the Philippines—to illustrate the complex relationship between migration, diffusion, critical events, and local conditions. Using a comparative research design and original materials, this article proposes a coevolutionary framework inspired by organization studies on the emergence of novelty. This article argues that the different diffusion processes and diffusion outcomes in the four cases are best explained through looking at network genesis mechanisms. This research contributes to the current studies on the diffusion of religion and scholarly interests in the global Tzu Chi movement.
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Dias, Fabio Boeira, C. M. Domingues, S. J. Marsland, S. M. Griffies, S. R. Rintoul, R. Matear, and R. Fiedler. "On the Superposition of Mean Advective and Eddy-Induced Transports in Global Ocean Heat and Salt Budgets." Journal of Climate 33, no. 3 (February 1, 2020): 1121–40. http://dx.doi.org/10.1175/jcli-d-19-0418.1.
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AbstractOcean thermal expansion is a large contributor to observed sea level rise, which is expected to continue into the future. However, large uncertainties exist in sea level projections among climate models, partially due to intermodel differences in ocean heat uptake and redistribution of buoyancy. Here, the mechanisms of vertical ocean heat and salt transport are investigated in quasi-steady-state model simulations using the Australian Community Climate and Earth-System Simulator Ocean Model (ACCESS-OM2). New insights into the net effect of key physical processes are gained within the superresidual transport (SRT) framework. In this framework, vertical tracer transport is dominated by downward fluxes associated with the large-scale ocean circulation and upward fluxes induced by mesoscale eddies, with two distinct physical regimes. In the upper ocean, where high-latitude water masses are formed by mixed layer processes, through cooling or salinification, the SRT counteracts those processes by transporting heat and salt downward. In contrast, in the ocean interior, the SRT opposes dianeutral diffusion via upward fluxes of heat and salt, with about 60% of the vertical heat transport occurring in the Southern Ocean. Overall, the SRT is largely responsible for removing newly formed water masses from the mixed layer into the ocean interior, where they are eroded by dianeutral diffusion. Unlike the classical advective–diffusive balance, dianeutral diffusion is bottom intensified above rough bottom topography, allowing an overturning cell to develop in alignment with recent theories. Implications are discussed for understanding the role of vertical tracer transport on the simulation of ocean climate and sea level.
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Fast, Idit. "Understanding Educational Policy Formation." Sociology of Education 89, no. 1 (November 22, 2015): 59–78. http://dx.doi.org/10.1177/0038040715615923.
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This study explores mechanisms underlying processes of educational policy formation. Previous studies have given much attention to processes of diffusion when accounting for educational policy formation. Less account has been given to the day-to-day institutional dynamics through which educational policies develop and change. Building on extensive governmental archival data, complemented with interviews and media analysis, I study the development and transformation of school violence policies in Israel. I argue that diffusion of global policy ideas and practices provides the menu of possible policies, while within-country struggles over legitimacy in the policy domain serve as a mechanism shaping which items on the menu becomes actual policy. Specifically, in the Israeli case, the interest in and action toward school violence were influenced by a global trend, but the actions of Psychological-Counseling Services (PCS) who struggled to assert their legitimacy as the authority on school violence in the Israeli Ministry of Education (MOE) shaped the adoption, rejection, and institutionalization of the specific school violence policy ideas and practices.
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Mehta, Chandrika, Uday Shankar, and Tapas K. Bandopadhyay. "Low Carbon Technologies for Our Cities of Future: Examining Mechanisms for Successful Transfer and Diffusion." India Quarterly: A Journal of International Affairs 72, no. 4 (November 28, 2016): 410–22. http://dx.doi.org/10.1177/0974928416671590.
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The urge to adopt the proceedings at the recently concluded COP-21 with a binding legal status is indicative of the fact that nations now realise the seriousness of the issue, alike. The international community is just paving way for a low carbon, energy efficient planet. Rapid urbanisation has led to overpopulated cities that demand better quality of life for its residents. On the one hand, there is a global urge to reduce greenhouse gas emissions and on the other hand, the world is moving towards a ‘smart’ future. Both these suppositions are interspersed by a common goal of sustainable development. Alternately, the discussion tends to focus on use of clean energy technologies. Cities will be at the centre of this unique and unprecedented challenge. This research seeks to explore the role that city governance plays in climate mitigation and adaptation at the global level. Furthermore, the article examines and evaluates low carbon technology as a choice to be inculcated in encountering climate change hazards and essentially looks into the modus operandi of the transfer and diffusion of low carbon/clean energy technologies.
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Chen, Li An, Xing Feng Zhu, and Ling Fu Chen. "First principles investigation of the diffusion of interstitial Cu, Ag and Au in ZnTe." International Journal of Modern Physics B 29, no. 19 (July 21, 2015): 1550130. http://dx.doi.org/10.1142/s0217979215501301.
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The diffusion is of great significance in many applications when the impurities are employed to tune the semiconductor's electrical or optical properties. It is necessary to understand how dopant defects diffuse in semiconductors. Using first-principles calculations, we consider interstitial diffusion mechanisms and calculate the migration barrier energies of interstitial Cu, Ag and Au atoms in II–VI compounds ZnTe. We find that the relative size of dopant and bulk atoms is an important factor which affects the diffusion behavior. The high symmetry Tc site, which is tetrahedrally coordinated by four cation atoms, is the global minimum energy location for Ag and Au interstitials. The size of Cu adatom is small, so Cu is more stable when it locates at the Ta site which is tetrahedrally coordinated by four anion atoms. But the global minimum energy location for Cu interstitials is M site which is of smaller space than Ta. Cu adatoms show an asymmetric curve of energy diffusion barrier with two energetically distinct extremum in the pathway. Ag diffuses along nearly straight line paths along [111] or equivalent directions. Diffusion for Cu or Au deviates from the straight line paths along 〈111〉 avoiding high symmetric sites.
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Almeida, Paul, and Chris Chase-Dunn. "Globalization and Social Movements." Annual Review of Sociology 44, no. 1 (July 30, 2018): 189–211. http://dx.doi.org/10.1146/annurev-soc-073117-041307.
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A growing body of scholarship acknowledges the increasing influence of global forces on social institutions and societies on multiple scales. We focus here on the role of globalization processes in shaping collective action and social movements. Three areas of global change and movements are examined: first, long-term global trends and collective action; second, research on national and local challenges to economic globalization, including backlash movements and the types of economic liberalization measures most associated with inducing oppositional movements; and third, the emergence of contemporary transnational social movements. In each of these arenas we address debates on diffusion, intervening mechanisms, and the outcomes of collective mobilization in response to global pressures.
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Lamas Galdo, M. I., J. D. Rodriguez García, and J. M. Rebollido Lorenzo. "Numerical Model to Analyze the Physicochemical Mechanisms Involved in CO2 Absorption by an Aqueous Ammonia Droplet." International Journal of Environmental Research and Public Health 18, no. 8 (April 13, 2021): 4119. http://dx.doi.org/10.3390/ijerph18084119.
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CO2 is the main anthropogenic greenhouse gas and its reduction plays a decisive role in reducing global climate change. As a CO2 elimination method, the present work is based on chemical absorption using aqueous ammonia as solvent. A CFD (computational fluid dynamics) model was developed to study CO2 capture in a single droplet. The objective was to identify the main mechanisms responsible for CO2 absorption, such as diffusion, solubility, convection, chemical dissociation, and evaporation. The proposed CFD model takes into consideration the fluid motion inside and outside the droplet. It was found that diffusion prevails over convection, especially for small droplets. Chemical reactions increase the absorption by up to 472.7% in comparison with physical absorption alone, and evaporation reduces the absorption up to 41.9% for the parameters studied in the present work.
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Meckling, Jonas, and Llewelyn Hughes. "Global interdependence in clean energy transitions." Business and Politics 20, no. 4 (December 2018): 467–91. http://dx.doi.org/10.1017/bap.2018.25.
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AbstractThe global energy industry is transforming as governments invest in clean energy technologies to address climate change, enhance energy security, and strengthen national competitiveness. Comparative research on clean energy transitions highlights the domestic drivers and constraints of clean energy transitions. This article contends that we need to understand the effects of global interdependence on clean energy transitions. Shifts in forms of interdependence between firms—influenced by the rise of global supply chains—have new implications for policy choices made by governments. Governments face more complex demands from domestic industries facing global economic competition, and act strategically in response to the actions of other governments, including sub-national actors, and firms in the global economy. We suggest that research on interdependence in clean energy transitions benefits from an analytical focus on mechanisms of transnational change such as cross-national and multi-level policy feedback and cross-national policy sequencing. Global interdependence has important implications for economic and environmental outcomes, affecting the durability of competitive advantage, and influencing the pace of the diffusion of clean energy technologies.
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Sparaco, Marco, Rosario Pascarella, Carmine Franco Muccio, and Marialuisa Zedde. "Forgetting the Unforgettable: Transient Global Amnesia Part I: Pathophysiology and Etiology." Journal of Clinical Medicine 11, no. 12 (June 12, 2022): 3373. http://dx.doi.org/10.3390/jcm11123373.
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Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of a temporary memory disorder with a profound anterograde amnesia and a variable impairment of the past memory. Since the first description, dating back over 60 years, several cases have beenreported in the literature. Nevertheless, TGA remains one of the most mysterious diseases in clinical neurology. The debate regarding the etiology of this disease has focused mainly on three different mechanisms: vascular (due to venous flow changes or focal arterial ischemia), epileptic, and migraine related. However, to date there is no scientific proof of any of these mechanisms. Furthermore, the demonstration by diffusion-weighted MRI of lesions in the CA1 field of the hippocampus cornu ammonis led us to hypothesize that the selective vulnerability of CA1 neurons to metabolic stress could play a role in the pathophysiology of TGA. In this review, we summarize current knowledge on the anatomy, vascularization and function of the hippocampus. Furthermore, we discuss the emerging theories on the etiology and the pathophysiological cascade leading to an impairment of hippocampal function during the attacks.
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Bachraoui, Moussa, Khalid Hattaf, and Noura Yousfi. "Analysis of a Fractional Reaction-Diffusion HBV Model with Cure of Infected Cells." Discrete Dynamics in Nature and Society 2020 (November 11, 2020): 1–8. http://dx.doi.org/10.1155/2020/3140275.
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In this paper, we propose a fractional reaction-diffusion model in order to better understand the mechanisms and dynamics of hepatitis B virus (HBV) infection in human body. The infection transmission is modeled by Hattaf–Yousfi functional response, and the fractional derivative is in the sense of Caputo. The global stability of the model equilibria is analyzed by means of Lyapunov functionals. Finally, numerical simulations are presented to support our analytical results.
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Dondio, Pierpaolo, Niccolo Casnici, and Flaminio Squazzoni. "Unpacking the Structure of Knowledge Diffusion in Wikipedia: Local Biases, Noble Prizes and the Wisdom of Crowds." Proceedings of the International AAAI Conference on Web and Social Media 9, no. 5 (August 3, 2021): 17–25. http://dx.doi.org/10.1609/icwsm.v9i5.14703.
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This paper investigates the diffusion of around 100,000 articles about literary authors in 52 versions of Wikipedia. We studied how Wiki versions replicate articles of authors belonging to a particular linguistic group and we collected findings about the potential mechanisms governing the replication process and its fairness. Results showed that diffusion of articles follows a power law, governed by strong preferences among versions, with a high number of isolated articles only present in one Wikipedia version. We found that the English Wiki has a prominent role in diffusing knowledge. However, results also showed that other Wikipedia versions were fundamental to building a rich global corpus of knowledge. Classical Greek and Latin authors resulted the most replicated set of entries. We found that geographic proximity and linguistic similarity was pivotal to explaining mutual links between Wikis. Finally, despite the presence of preference mechanisms, we found how the relative importance that each Wikipedia versions assigns to the set of authors of each language is significantly correlated with an expert-based ranking built on the outcome of various international literary awards, including the Nobel Prize. Moreover, we showed how Wikipedia exhibits a strong Wisdom of Crowds effect, with the collective opinion of all the Wikipedia versions showing a correlation with the experts higher than any individual Wikipedia version, with a value for Pearson's’ r of about 0.9.
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Marquis, Christopher, Juelin Yin, and Dongning Yang. "State-Mediated Globalization Processes and the Adoption of Corporate Social Responsibility Reporting in China." Management and Organization Review 13, no. 1 (March 2017): 167–91. http://dx.doi.org/10.1017/mor.2016.55.
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ABSTRACTDespite the prevalence of global diffusion, little is known about the processes by which international practices are adopted and adapted within organizations around the world. Through our qualitative research on the introduction of corporate social responsibility (CSR) reporting at two leading Chinese companies, we identify a unique set of political mechanisms that we labelstate-mediated globalization, whereby powerful nation-state actors influence the ways in which corporations adopt and adapt global norms and practices. We find that businesses’ needs for political legitimacy from a key stakeholder, in this case the government, leads them to deviate systematically from the global practice in bothformandcontent. These intentional practice adaptations are then legitimized by the government to createinternationalization toolsandlocalized standardsto aid adoption by other organizations. Our findings illustrate previously unidentified mechanisms by which powerful stakeholders such as the Chinese government may mediate, and thereby direct, the ways in which corporations adopt and adapt global CSR practices. Contributions to understanding the political processes of institutional translation in the context of globalization are discussed.
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Tredenick, Eloise C., Troy W. Farrell, and W. Alison Forster. "Mathematical Modelling of Hydrophilic Ionic Fertiliser Diffusion in Plant Cuticles: Lipophilic Surfactant Effects." Plants 8, no. 7 (July 2, 2019): 202. http://dx.doi.org/10.3390/plants8070202.
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The global agricultural industry requires improved efficacy of sprays being applied to weeds and crops to increase financial returns and reduce environmental impact. Enhancing foliar penetration is one way to improve efficacy. Within the plant leaf, the cuticle is the most significant barrier to agrochemical diffusion. It has been noted that a comprehensive set of mechanisms for ionic active ingredient (AI) penetration through plant leaves with surfactants is not well defined, and oils that enhance penetration have been given little attention. The importance of a mechanistic mathematical model has been noted previously in the literature. Two mechanistic mathematical models have been previously developed by the authors, focusing on plant cuticle penetration of calcium chloride through tomato fruit cuticles. The models included ion binding and evaporation with hygroscopic water absorption, along with the ability to vary the AI concentration and type, relative humidity, and plant species. Here, we further develop these models to include lipophilic adjuvant effects, as well as the adsorption and desorption, of compounds on the cuticle surface with a novel Adaptive Competitive Langmuir model. These modifications to a penetration model provide a novel addition to the literature. We validate our theoretical model results against appropriate experimental data, discuss key sensitivities, and relate theoretical predictions to physical mechanisms. The results indicate the addition of the desorption mechanism may be one way to predict increased penetration at late times, and the sensitivity of model parameters compares well to those present in the literature.
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Mittal, Nitin, Urvinder Singh, and Balwinder Singh Sohi. "Modified Grey Wolf Optimizer for Global Engineering Optimization." Applied Computational Intelligence and Soft Computing 2016 (2016): 1–16. http://dx.doi.org/10.1155/2016/7950348.
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Nature-inspired algorithms are becoming popular among researchers due to their simplicity and flexibility. The nature-inspired metaheuristic algorithms are analysed in terms of their key features like their diversity and adaptation, exploration and exploitation, and attractions and diffusion mechanisms. The success and challenges concerning these algorithms are based on their parameter tuning and parameter control. A comparatively new algorithm motivated by the social hierarchy and hunting behavior of grey wolves is Grey Wolf Optimizer (GWO), which is a very successful algorithm for solving real mechanical and optical engineering problems. In the original GWO, half of the iterations are devoted to exploration and the other half are dedicated to exploitation, overlooking the impact of right balance between these two to guarantee an accurate approximation of global optimum. To overcome this shortcoming, a modified GWO (mGWO) is proposed, which focuses on proper balance between exploration and exploitation that leads to an optimal performance of the algorithm. Simulations based on benchmark problems and WSN clustering problem demonstrate the effectiveness, efficiency, and stability of mGWO compared with the basic GWO and some well-known algorithms.
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Guenet, B., T. Eglin, N. Vasilyeva, P. Peylin, P. Ciais, and C. Chenu. "The relative importance of decomposition and transport mechanisms in accounting for C profiles." Biogeosciences Discussions 9, no. 10 (October 15, 2012): 14145–73. http://dx.doi.org/10.5194/bgd-9-14145-2012.
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Abstract. Soil is the major terrestrial reservoirs of carbon, and a substantial part of this carbon is stored in deep layers, typically deeper than 50 cm below the surface. Several studies underlined the quantitative importance of this deep Soil Organic Carbon (SOC) pool and models are needed to better understand this stock and its evolution under climate and land-uses changes. In this study, we test and compare 3 simple theoretical models of vertical transport for SOC against SOC profiles measurements from a long-term bare fallow experiment carried out by the Central-Chernozem State Natural Biosphere Reserve named after V.V. Alekhin, in the Kursk Region of Russia. The transport schemes tested are diffusion, advection or both diffusion and advection. They are coupled to two different formulations of soil carbon decomposition kinetics. The first formulation is a first order kinetics widely used in global SOC decomposition models; the second one links SOC decomposition rate to the amount of fresh organic matter, representing a "priming effect". Field data are from a set of three bare fallow plots where soil received no input during the past 20, 26 and 58 yr respectively. Parameters of the models were optimized using a Bayesian method. The best results are obtained when SOC decomposition is assumed to be controlled by fresh organic matter. In comparison to the first-order kinetic model, the "priming" model reduces the underestimation of SOC decomposition in the top layers and the over estimation in the deep layers. We also observe that the transport scheme that improved the fit with the data depends on the soil carbon mineralization formulation chosen. When soil carbon decomposition is modelled to depend on the fresh organic matter amount, the transport mechanisms which improves best the fit to the SOC profile data is the model representing both advection and diffusion. Interestingly, the older the bare fallow is, the lesser the need for diffusion is. This suggests that stabilized carbon may not be transported within the profile by the same mechanisms than more labile carbon.
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Ha, Yoo Jung, and Yingqi Wei. "Dual isomorphic mechanisms and the role of a transnational agent." Multinational Business Review 27, no. 3 (September 16, 2019): 266–84. http://dx.doi.org/10.1108/mbr-06-2017-0035.
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Purpose Corporate environmental innovation (CEI) is a proactive type of response to increasing public scrutiny regarding firms’ environmental performance. While past studies have overwhelmingly focused on coercive mechanisms and assumed a closed national institutional field, less attention has been given to non-coercive and transnational inter-firm mimetic mechanisms. This paper aims to investigate the joint effect of coercive isomorphic mechanisms from domestic institutions and mimetic isomorphic mechanisms from foreign multinational enterprises (MNE) on CEI adoption in domestic firms. Design/methodology/approach The study’s empirical analysis is based on data from 1,967 firms from the 2010 Korean Innovation Survey, as well as other official statistics. Findings This study reports the following results: the direct effects of domestic institutions on CEI adoption in domestic firms vary according to institution type; foreign MNEs have a positive effect, whether using global or local CEI strategies; and the positive effect of foreign MNEs strengthens when the stringency of domestic environmental regulation increases. Originality/value This paper shows that CEI diffusion is driven by both coercive institutional pressures and inter-firm mimetic mechanisms, including their joint effects. Foreign MNEs act as boundary-spanners that activate a dual isomorphic mechanism, affecting social as well as economic development in host countries. Finally, evidence of interaction between domestic coercive and transnational mimetic mechanisms supports the authors’ contention that national institutional fields are increasingly interconnected.
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Dziedzic, Anna. "Foreign judges of the Pacific as agents of global constitutionalism." Global Constitutionalism 10, no. 2 (July 2021): 351–66. http://dx.doi.org/10.1017/s2045381720000210.
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AbstractStudies of global constitutionalism have focused on the transnational movement of constitutional law through the citation of foreign judgments. However, little attention has been paid to the movement of constitutional judges themselves. This article considers how the foreign judges who sit on courts of constitutional jurisdiction in Pacific island states can be understood as part of the phenomenon of global constitutionalism. It identifies three ways in which foreign judges can be agents of global constitutionalism: as mechanisms for the diffusion of constitutional ideas, as expressions of global constitutional values and as objects of transnational legal transfer. An empirical analysis comparing the citation practices of local and foreign judges in constitutional cases in nine Pacific states suggests that the use of foreign judges on constitutional courts does contribute to the international movement of constitutional ideas. However, a critical analysis of foreign judges as expressions and objects of global constitutionalism sheds light on a range of tensions in the role of constitutional judges and understandings of global constitutionalism.
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Funk, Jeffrey L., and David T. Methe. "Market- and committee-based mechanisms in the creation and diffusion of global industry standards: the case of mobile communication." Research Policy 30, no. 4 (April 2001): 589–610. http://dx.doi.org/10.1016/s0048-7333(00)00095-0.
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D'HERNONCOURT, J., A. DE WIT, and A. ZEBIB. "Double-diffusive instabilities of autocatalytic chemical fronts." Journal of Fluid Mechanics 576 (March 28, 2007): 445–56. http://dx.doi.org/10.1017/s0022112007004673.
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Convective instabilities of an autocatalytic propagating chemical front in a porous medium are studied. The front creates temperature and concentration gradients which then generate a density gradient. If the front propagates in the direction of the gravity field, adverse density stratification can lead to Rayleigh–Taylor or Rayleigh–Bénard instabilities. Differential diffusivity of mass and heat can also destabilize the front because of the double-diffusive phenomena. We compare the stability boundaries for the classical hydrodynamic case of a bounded layer without reaction and for the chemical front in the parameter space spanned by the thermal and solutal Rayleigh numbers. We show that chemical reactions profoundly affect the stability boundaries compared to the non-reactive situation because of a delicate coupling between the double-diffusive and Rayleigh–Taylor mechanisms with localized density perturbations driven by the reaction. In the reactive case, a linear stability analysis identifies three distinct stationary branches of the instability. They bound a region of stability that shrinks with increasing Lewis number, in marked contrast to the classical double-diffusive layer. In particular a region of global and local stable stratification is susceptible to a counter-intuitive mechanism of convective instability driven by chemistry and double-diffusion. The other two regions display an additional contribution of localized Rayleigh–Taylor instabilities. Displaced-particle arguments are employed in support of and to elucidate the entire stability boundary.
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Vanderhill, Rachel. "Active resistance to democratic diffusion." Communist and Post-Communist Studies 50, no. 1 (January 9, 2017): 41–51. http://dx.doi.org/10.1016/j.postcomstud.2017.01.003.
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Recent research on the international diffusion of democracy has focused on demonstrating how diffusion can change regime outcomes. Although there is still debate within the field of democratization over how important democratic diffusion is relative to domestic factors, autocratic leaders believe that democratic diffusion can be a threat to their rule. It is clear that some countries, such as North Korea, prevent diffusion by severely restricting interactions with foreigners and forbidding access to external sources of information. The more intriguing question is how the states that have economic, diplomatic, and social linkages with democratic states prevent democratic diffusion. In other words, what methods do globally-engaged, autocratic governments use to limit exposure to and reduce receptivity to democratic diffusion? In addition to using coercion and economic patronage, autocratic states utilize two nonmaterial mechanisms to prevent democratic diffusion: 1) restricting exposure to democratic ideas and 2) developing alternative narratives about democracy to reduce local receptivity to democratic diffusion. Sophisticated autocratic leaders can limit receptivity to democratic diffusion if they convince citizens that those ideas are “foreign,” will cause “chaos,” or if they believe they already have their own form of democracy. I explore these methods of establishing firewalls to prevent diffusion by examining the cases of China and Kazakhstan, two countries where a high level of economic linkage coincides with a successful continuation of autocratic rule, despite the global spread of democratic norms. China has developed extensive methods to restrict access to foreign ideas about democracy while Kazakhstan has mainly focused on developing an alternative narrative about democracy. This article contributes to the literature on authoritarian persistence and democratic diffusion by investigating the internal methods autocratic leaders adopt to ensure that democratic diffusion does not threaten their rule.
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Winkler, Michael. "Global generalized solutions to a multi-dimensional doubly tactic resource consumption model accounting for social interactions." Mathematical Models and Methods in Applied Sciences 29, no. 03 (March 2019): 373–418. http://dx.doi.org/10.1142/s021820251950012x.
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This work is concerned with a prototypical model for the spatio-temporal evolution of a forager–exploiter system, consisting of two species which simultaneously consume a common nutrient, and which interact through a taxis-type mechanism according to which individuals from the exploiter subpopulation move upward density gradients of the forager subgroup. Specifically, the model [Formula: see text] for the population densities [Formula: see text] and [Formula: see text] of foragers and exploiters, as well as the nutrient concentration [Formula: see text], is considered in smoothly bounded domains [Formula: see text], [Formula: see text]. It is first shown that under an explicit condition linking the sizes of the resource production rate [Formula: see text] and of the initial nutrient concentration, an associated Neumann-type initial-boundary value problem admits a global solution within an appropriate generalized concept. The second of the main results asserts stabilization of these solutions toward spatially homogeneous equilibria in the large time limit, provided that [Formula: see text] satisfies a mild assumption on temporal decay. To the best of our knowledge, these are the first rigorous analytical results addressing taxis-type cross-diffusion mechanisms coupled in a cascade-like manner as in (⋆).
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Sikkink, Kathryn. "From Pariah State to Global Protagonist: Argentina and the Struggle for International Human Rights." Latin American Politics and Society 50, no. 1 (2008): 1–29. http://dx.doi.org/10.1111/j.1548-2456.2008.00002.x.
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AbstractDemocratizing states began in the 1980s to hold individuals, including past heads of state, accountable for human rights violations. The 1984 Argentine truth commission report (Nunca Más) and the 1985 trials of the juntas helped to initiate this trend. Argentina also developed other justice-seeking mechanisms, including the first groups of mothers and grandmothers of the disappeared, the first human rights forensic anthropology team, and the first truth trials. Argentines helped to define the very termforced disappearanceand to develop regional and international instruments to end the practice. Argentina thus illustrates the potential for global human rights protagonism and diffusion of ideas from a country outside the wealthy North. This article surveys Argentina's innovations and proposes possible explanations, drawing on theoretical studies from transitional justice, social movements, and norms cascades in international relations.
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Guenet, B., T. Eglin, N. Vasilyeva, P. Peylin, P. Ciais, and C. Chenu. "The relative importance of decomposition and transport mechanisms in accounting for soil organic carbon profiles." Biogeosciences 10, no. 4 (April 10, 2013): 2379–92. http://dx.doi.org/10.5194/bg-10-2379-2013.
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Abstract. Soil is the major terrestrial reservoir of carbon and a substantial part of this carbon is stored in deep layers, typically deeper than 50 cm below the surface. Several studies underlined the quantitative importance of this deep soil organic carbon (SOC) pool and models are needed to better understand this stock and its evolution under climate and land-uses changes. In this study, we tested and compared three simple theoretical models of vertical transport for SOC against SOC profiles measurements from a long-term bare fallow experiment carried out by the Central-Chernozem State Natural Biosphere Reserve in the Kursk Region of Russia. The transport schemes tested are diffusion, advection and both diffusion and advection. They are coupled to three different formulations of soil carbon decomposition kinetics. The first formulation is a first order kinetics widely used in global SOC decomposition models; the second one, so-called "priming" model, links SOC decomposition rate to the amount of fresh organic matter, representing the substrate interactions. The last one is also a first order kinetics, but SOC is split into two pools. Field data are from a set of three bare fallow plots where soil received no input during the past 20, 26 and 58 yr, respectively. Parameters of the models were optimised using a Bayesian method. The best results are obtained when SOC decomposition is assumed to be controlled by fresh organic matter (i.e., the priming model). In comparison to the first-order kinetic model, the priming model reduces the overestimation in the deep layers. We also observed that the transport scheme that improved the fit with the data depended on the soil carbon mineralisation formulation chosen. When soil carbon decomposition was modelled to depend on the fresh organic matter amount, the transport mechanism which improved best the fit to the SOC profile data was the model representing both advection and diffusion. Interestingly, the older the bare fallow is, the lesser the need for diffusion is, suggesting that stabilised carbon may not be transported within the profile by the same mechanisms than more labile carbon.
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Shen, Jun, Daniel J. Tozer, Hugh S. Markus, and Jonathan Tay. "Network Efficiency Mediates the Relationship Between Vascular Burden and Cognitive Impairment." Stroke 51, no. 6 (June 2020): 1682–89. http://dx.doi.org/10.1161/strokeaha.119.028587.
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Background and Purpose— Cerebrovascular disease contributes to age-related cognitive decline, but the mechanisms underlying this phenomenon remain incompletely understood. We hypothesized that vascular risk factors would lead to cognitive impairment through the disruption of brain white matter network efficiency. Methods— Participants were 19 346 neurologically healthy individuals from UK Biobank that underwent diffusion MRI and cognitive testing (mean age=62.6). Global efficiency, a measure of network integration, was calculated from white matter networks constructed using deterministic diffusion tractography. First, we determined whether demographics (age, sex, ethnicity, socioeconomic status, and education), vascular risk factors (hypertension, hypercholesterolemia, diabetes mellitus, smoking, body mass index), and white matter hyperintensities were related to global efficiency using multivariate linear regression. Next, we used structural equation modeling to model a multiple regression. The dependent variable was a latent cognition variable using all cognitive data, while independent variables were a latent factor including all vascular risk factors (vascular burden), demographic variables, white matter hyperintensities, and global efficiency. Finally, we used mediation analysis to determine whether global efficiency explained the relationship between vascular burden and cognition. Results— Hypertension and diabetes mellitus were consistently associated with reduced global efficiency even after controlling for white matter hyperintensities. Structural equation models revealed that vascular burden was associated with cognition ( P =0.023), but not after adding global efficiency to the model ( P =0.09), suggesting a mediation effect. Mediation analysis revealed a significant indirect effect of global efficiency on cognition through vascular burden ( P <0.001), suggesting a partial mediation effect. Conclusions— Vascular burden is associated with reduced global efficiency and cognitive impairment in the general population. Network efficiency partially mediates the relationship between vascular burden and cognition. This suggests that treating specific risk factors may prevent reductions in brain network efficiency and preserve cognitive functioning in the aging population.
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Gunitsky, Seva. "Complexity and theories of change in international politics." International Theory 5, no. 1 (March 2013): 35–63. http://dx.doi.org/10.1017/s1752971913000110.
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This article examines how the principles of complex systems can illuminate recurring mechanisms of change in theories of international relations. It applies the logic of complex systems to two specific puzzles in international politics – the problem of theorizing change in structural realism, and the dynamics of cross-border democratic diffusion. In the first case, by shifting the analysis of anarchy's consequences from state behavior to state attributes, complex systems can illustrate the sources of domestic and international transformations embedded in structural theories. This approach offers a way to think about democratization as a global process of interstate competition and socialization driven by the pressures of anarchy. In the second case, the principles of co-adaptation in complex systems can help reframe diffusion not as the unilinear spread of democracy but as the interplay of self-reinforcing and self-dampening dynamics, whose interaction shapes both actor expectations and democratic outcomes. In both cases, complex systems serve a limited but useful role; although not conducive to theory creation, the approach provides a useful analytical prism for examining patterns of change and continuity in global processes, and highlights concrete ways of improving models of transformations in international politics.
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Badger, Marcus P. S. "Alkenone isotopes show evidence of active carbon concentrating mechanisms in coccolithophores as aqueous carbon dioxide concentrations fall below 7 µmol L<sup>−1</sup>." Biogeosciences 18, no. 3 (February 15, 2021): 1149–60. http://dx.doi.org/10.5194/bg-18-1149-2021.
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Abstract. Coccolithophores and other haptophyte algae acquire the carbon required for metabolic processes from the water in which they live. Whether carbon is actively moved across the cell membrane via a carbon concentrating mechanism, or passively through diffusion, is important for haptophyte biochemistry. The possible utilization of carbon concentrating mechanisms also has the potential to over-print one proxy method by which ancient atmospheric CO2 concentration is reconstructed using alkenone isotopes. Here I show that carbon concentrating mechanisms are likely used when aqueous carbon dioxide concentrations are below 7 µmol L−1. I compile published alkenone-based CO2 reconstructions from multiple sites over the Pleistocene and recalculate them using a common methodology, which allows comparison to be made with ice core CO2 records. Interrogating these records reveals that the relationship between proxy CO2 and ice core CO2 breaks down when local aqueous CO2 concentration falls below 7 µmol L−1. The recognition of this threshold explains why many alkenone-based CO2 records fail to accurately replicate ice core CO2 records, and it suggests the alkenone proxy is likely robust for much of the Cenozoic when this threshold was unlikely to be reached in much of the global ocean.
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Forliti, David J., and Paul J. Strykowski. "Controlling Turbulence in a Rearward-Facing Step Combustor Using Countercurrent Shear." Journal of Fluids Engineering 127, no. 3 (January 25, 2005): 438–48. http://dx.doi.org/10.1115/1.1899170.
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The present work describes the application of countercurrent shear flow control to the nonreacting flow in a novel step combustor. The countercurrent shear control employs a suction based approach, which induces counterflow through a gap at the sudden expansion plane. Peak turbulent fluctuation levels, cross-stream averaged turbulent kinetic energy, and cross-stream momentum diffusion increased with applied suction. The control downstream of the step operates via two mechanisms: enhanced global recirculation and near field control of the separated shear layer. The use of counterflow also enhances three dimensionality, a feature that is expected to be beneficial under burning conditions.
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Bartsch, Thorsten, Juliane Döhring, Sigrid Reuter, Carsten Finke, Axel Rohr, Henriette Brauer, Günther Deuschl, and Olav Jansen. "Selective Neuronal Vulnerability of Human Hippocampal CA1 Neurons: Lesion Evolution, Temporal Course, and Pattern of Hippocampal Damage in Diffusion-Weighted MR Imaging." Journal of Cerebral Blood Flow & Metabolism 35, no. 11 (June 17, 2015): 1836–45. http://dx.doi.org/10.1038/jcbfm.2015.137.
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The CA1 (cornu ammonis) region of hippocampus is selectively vulnerable to a variety of metabolic and cytotoxic insults, which is mirrored in a delayed neuronal death of CA1 neurons. The basis and mechanisms of this regional susceptibility of CA1 neurons are poorly understood, and the correlates in human diseases affecting the hippocampus are not clear. Adopting a translational approach, the lesion evolution, temporal course, pattern of diffusion changes, and damage in hippocampal CA1 in acute neurologic disorders were studied using high-resolution magnetic resonance imaging. In patients with hippocampal ischemia ( n = 50), limbic encephalitis ( n = 30), after status epilepticus ( n = 17), and transient global amnesia ( n = 53), the CA1 region was selectively affected compared with other CA regions of the hippocampus. CA1 neurons exhibited a maximum decrease of apparent diffusion coefficient (ADC) 48 to 72 hours after the insult, irrespective of the nature of the insult. Hypoxic-ischemic insults led to a significant lower ADC suggesting that the ischemic insult results in a stronger impairment of cellular metabolism. The evolution of diffusion changes show that CA1 diffusion lesions mirror the delayed time course of the pathophysiologic cascade typically observed in animal models. Studying the imaging correlates of hippocampal damage in humans provides valuable insight into the pathophysiology and neurobiology of the hippocampus.
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Lin, Hsiu-Fen. "Antecedents and consequences of electronic supply chain management diffusion." International Journal of Logistics Management 28, no. 2 (May 8, 2017): 699–718. http://dx.doi.org/10.1108/ijlm-01-2016-0023.
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Purpose Grounded in the resource-based view and social exchange theory, the purpose of this paper is to develop a research model that offers a comprehensive understanding of the antecedents and consequences of electronic supply chain management (e-SCM) diffusion. Design/methodology/approach Survey data from 142 managers (in charge of e-SCM projects in their companies) of large Taiwanese firms were collected and used to test the hypotheses using hierarchical moderated regression analysis. Findings The results indicate that information technology deployment capability, operational capability, human resource capability, and knowledge sharing are important antecedents of e-SCM diffusion. In turn, higher levels of e-SCM diffusion lead to greater competitive performance. This study also finds that knowledge sharing plays a moderating role by strengthening the relationship between organizational capabilities (e.g. operational capability and human resource capability) and e-SCM diffusion. Practical implications Managers should recognize that human resource development activities (recruiting, training, and managing valuable e-SCM personnel) are an important source of e-SCM diffusion. Similarly, managers must establish the connection between human resource capabilities and e-SCM diffusion (i.e. “soft-side” e-SCM) such as hiring and retaining skilled e-SCM personnel, training and development for e-SCM personnel, and measuring e-SCM personnel’s global mindset over time. Originality/value Theoretically, this study aims to provide a research model that is capable of understanding the antecedents and consequences of e-SCM diffusion. From the managerial perspective, the findings of this study provide valuable decision guides for practitioners to help them identify and develop firm internal capabilities and social mechanisms that foster e-SCM diffusion.
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Bouttes, N., D. Paillard, D. M. Roche, C. Waelbroeck, M. Kageyama, A. Lourantou, E. Michel, and L. Bopp. "Impact of oceanic processes on the carbon cycle during the last termination." Climate of the Past Discussions 7, no. 3 (June 14, 2011): 1887–934. http://dx.doi.org/10.5194/cpd-7-1887-2011.
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Abstract. During the last termination (from ~18 000 yr ago to ~9000 yr ago) the climate significantly warmed and the ice sheets melted. Simultaneously, atmospheric CO2 increased from ~190 ppm to ~260 ppm. Although this CO2 rise plays an important role in the deglacial warming, the reasons for its evolution are difficult to explain. Only box models have been used to run transient simulations of this carbon cycle transition, but by forcing the model with data constrained scenarios of the evolution of temperature, sea level, sea ice, NADW formation, Southern Ocean vertical mixing and biological carbon pump. More complex models (including GCMs) have investigated some of these mechanisms but they have only been used to try and explain LGM versus present day steady-state climates. In this study we use a climate-carbon coupled model of intermediate complexity to explore the role of three oceanic processes in transient simulations: the sinking of brines, stratification-dependant diffusion and iron fertilization. Carbonate compensation is accounted for in these simulations. We show that neither iron fertilization nor the sinking of brines alone can account for the evolution of CO2, and that only the combination of the sinking of brines and interactive diffusion can simultaneously simulate the increase in deep Southern Ocean δ13C. The scenario that agrees best with the data takes into account all mechanisms and favours a rapid cessation of the sinking of brines around 18 000 yr ago, when the Antarctic ice sheet extent was at its maximum. Sea ice formation was then shifted to the open ocean where the salty water is quickly mixed with fresher water, which prevents deep sinking of salty water and therefore breaks down the deep stratification and releases carbon from the abyss. Based on this scenario it is possible to simulate both the amplitude and timing of the CO2 increase during the last termination in agreement with data. The atmospheric δ13C appears to be highly sensitive to changes in the terrestrial biosphere, underlining the need to better constrain the vegetation evolution during the termination.
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Perrinet, Laurent U., and Guillaume S. Masson. "Motion-Based Prediction Is Sufficient to Solve the Aperture Problem." Neural Computation 24, no. 10 (October 2012): 2726–50. http://dx.doi.org/10.1162/neco_a_00332.
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In low-level sensory systems, it is still unclear how the noisy information collected locally by neurons may give rise to a coherent global percept. This is well demonstrated for the detection of motion in the aperture problem: as luminance of an elongated line is symmetrical along its axis, tangential velocity is ambiguous when measured locally. Here, we develop the hypothesis that motion-based predictive coding is sufficient to infer global motion. Our implementation is based on a context-dependent diffusion of a probabilistic representation of motion. We observe in simulations a progressive solution to the aperture problem similar to physio-logy and behavior. We demonstrate that this solution is the result of two underlying mechanisms. First, we demonstrate the formation of a tracking behavior favoring temporally coherent features independent of their texture. Second, we observe that incoherent features are explained away, while coherent information diffuses progressively to the global scale. Most previous models included ad hoc mechanisms such as end-stopped cells or a selection layer to track specific luminance-based features as necessary conditions to solve the aperture problem. Here, we have proved that motion-based predictive coding, as it is implemented in this functional model, is sufficient to solve the aperture problem. This solution may give insights into the role of prediction underlying a large class of sensory computations.
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Graham, Laura, and David Risk. "Explaining CO<sub>2</sub> fluctuations observed in snowpacks." Biogeosciences 15, no. 3 (February 9, 2018): 847–59. http://dx.doi.org/10.5194/bg-15-847-2018.
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Abstract. Winter soil carbon dioxide (CO2) respiration is a significant and understudied component of the global carbon (C) cycle. Winter soil CO2 fluxes can be surprisingly variable, owing to physical factors such as snowpack properties and wind. This study aimed to quantify the effects of advective transport of CO2 in soil–snow systems on the subdiurnal to diurnal (hours to days) timescale, use an enhanced diffusion model to replicate the effects of CO2 concentration depletions from persistent winds, and use a model–measure pairing to effectively explore what is happening in the field. We took continuous measurements of CO2 concentration gradients and meteorological data at a site in the Cape Breton Highlands of Nova Scotia, Canada, to determine the relationship between wind speeds and CO2 levels in snowpacks. We adapted a soil CO2 diffusion model for the soil–snow system and simulated stepwise changes in transport rate over a broad range of plausible synthetic cases. The goal was to mimic the changes we observed in CO2 snowpack concentration to help elucidate the mechanisms (diffusion, advection) responsible for observed variations. On subdiurnal to diurnal timescales with varying winds and constant snow levels, a strong negative relationship between wind speed and CO2 concentration within the snowpack was often identified. Modelling clearly demonstrated that diffusion alone was unable to replicate the high-frequency CO2 fluctuations, but simulations using above-atmospheric snowpack diffusivities (simulating advective transport within the snowpack) reproduced snow CO2 changes of the observed magnitude and speed. This confirmed that wind-induced ventilation contributed to episodic pulsed emissions from the snow surface and to suppressed snowpack concentrations. This study improves our understanding of winter CO2 dynamics to aid in continued quantification of the annual global C cycle and demonstrates a preference for continuous wintertime CO2 flux measurement systems.
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Dorman, L. I. "Prediction of galactic cosmic ray intensity variation for a few (up to 10-12) years ahead on the basis of convection-diffusion and drift model." Annales Geophysicae 23, no. 9 (November 22, 2005): 3003–7. http://dx.doi.org/10.5194/angeo-23-3003-2005.
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Abstract. We determine the dimension of the Heliosphere (modulation region), radial diffusion coefficient and other parameters of convection-diffusion and drift mechanisms of cosmic ray (CR) long-term variation, depending on particle energy, the level of solar activity (SA) and general solar magnetic field. This important information we obtain on the basis of CR and SA data in the past, taking into account the theory of convection-diffusion and drift global modulation of galactic CR in the Heliosphere. By using these results and the predictions which are regularly published elsewhere of expected SA variation in the near future and prediction of next future SA cycle, we may make a prediction of the expected in the near future long-term cosmic ray intensity variation. We show that by this method we may make a prediction of the expected in the near future (up to 10-12 years, and may be more, in dependence for what period can be made definite prediction of SA) galactic cosmic ray intensity variation in the interplanetary space on different distances from the Sun, in the Earth's magnetosphere, and in the atmosphere at different altitudes and latitudes.
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Miyazaki, Kazuyuki, and Toshiki Iwasaki. "The Gradient Genesis of Stratospheric Trace Species in the Subtropics and around the Polar Vortex." Journal of the Atmospheric Sciences 65, no. 2 (February 1, 2008): 490–508. http://dx.doi.org/10.1175/2007jas2403.1.
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Abstract Mechanisms that control the formation and decay of meridional gradients in stratospheric trace species in the subtropics and around the polar vortex are investigated using a gradient genesis equation that uses mass-weighted isentropic zonal means. Application of this method to global nitrous oxide (N2O) data output from a global chemical transport model shows that mean vertical transport increases the meridional tracer gradient from the subtropics to midlatitudes through the shearing deformation, particularly related to overturning of the Brewer–Dobson circulation. Mean meridional transport advects the subtropical tracer gradient toward midlatitudes, while the eddy stairstep effect, steepening at the edge of the well-mixed region because of a meridional gradient in the diffusion coefficient, increases the tracer gradient in the subtropics and around the polar vortex. Mechanisms controlling the evolution of the tracer gradients in the subtropics differ between spring and autumn. The autumnal subtropical tracer gradient maximum is generated mainly from shearing deformation of the mean vertical transport, but less from mean and eddy meridional fluxes. In spring, the eddy stairstep effect also contributes to the generation of the subtropical tracer gradient maximum. Strong divergence forces stretching deformation that causes the springtime subtropical tracer gradient to decay. The gradient genesis mechanism around the Antarctic polar vortex is significantly different from that in the subtropics. Development of the tracer gradient around the Antarctic polar vortex is mostly controlled by mean meridional stretching motion in the middle stratosphere. Vertical advection and eddy smoothing effects flatten the tracer gradient as the polar vortex decays.
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Qadri, Ubaid Ali, Gary J. Chandler, and Matthew P. Juniper. "Self-sustained hydrodynamic oscillations in lifted jet diffusion flames: origin and control." Journal of Fluid Mechanics 775 (June 19, 2015): 201–22. http://dx.doi.org/10.1017/jfm.2015.297.
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We use direct numerical simulation (DNS) of the Navier–Stokes equations in the low-Mach-number limit to investigate the hydrodynamic instability of a lifted jet diffusion flame. We obtain steady solutions for flames using a finite rate reaction chemistry, and perform a linear global stability analysis around these steady flames. We calculate the direct and adjoint global modes and use these to identify the regions of the flow that are responsible for causing oscillations in lifted jet diffusion flames, and to identify how passive control strategies might be used to control these oscillations. We also apply a local stability analysis to identify the instability mechanisms that are active. We find that two axisymmetric modes are responsible for the oscillations. The first is a high-frequency mode with wavemaker in the jet shear layer in the premixing zone. The second is a low-frequency mode with wavemaker in the outer part of the shear layer in the flame. We find that both of these modes are most sensitive to feedback involving perturbations to the density and axial momentum. Using the local stability analysis, we find that the high-frequency mode is caused by a resonant mode in the premixing region, and that the low-frequency mode is caused by a region of local absolute instability in the flame, not by the interaction between resonant modes, as proposed in Nichols et al. (Phys. Fluids, vol. 21, 2009, article 015110). Our linear analysis shows that passive control of the low-frequency mode may be feasible because regions up to three diameters away from the fuel jet are moderately sensitive to steady control forces.
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Raezah, Aeshah A. "Dynamical Analysis of Secondary Dengue Viral Infection with Multiple Target Cells and Diffusion by Mathematical Model." Discrete Dynamics in Nature and Society 2022 (November 21, 2022): 1–24. http://dx.doi.org/10.1155/2022/2106910.
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Dengue is an epidemic disease rapidly spreading throughout many parts of the world, which is a serious public health concern. Understanding disease mechanisms through mathematical modeling is one of the most effective tools for this purpose. The aim of this manuscript is to develop and analyze a dynamical system of PDEs that describes the secondary infection caused by DENV, considering (i) the diffusion due to spatial mobility of cells and DENV particles, (ii) the interactions between multiple target cells, DENV, and antibodies of two types (heterologous and homologous). Global existence, positivity, and boundedness are proved for the system with homogeneous Neumann boundary conditions. Three threshold parameters are computed to characterize the existence and stability conditions of the model’s four steady states. Via means of Lyapunov functional, the global stability of all steady states is carried out. Our results show that the uninfected steady state is globally asymptotically stable if the basic reproduction number is less than or equal to unity, which leads to the disappearance of the disease from the body. When the basic reproduction number is greater than unity, the disease persists in the body with an active or inactive immune antibody response. To demonstrate such theoretical results, numerical simulations are presented.
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Ferreira, S. E. S., M. S. Potgieter, B. Heber, and H. Fichtner. "Charge-sign dependent modulation in the heliosphere over a 22-year cycle." Annales Geophysicae 21, no. 6 (June 30, 2003): 1359–66. http://dx.doi.org/10.5194/angeo-21-1359-2003.
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Abstract. A time-dependent model based on a numerical solution of Parker’s transport equation is used to model the modulation of cosmic ray protons, electrons and helium for full 11-year and 22-year modulation cycles using a compound approach. This approach incorporates the concept of propagating diffusion barriers based on global increases in the heliospheric magnetic field as they propagate from the Sun throughout the heliosphere, combined with gradient, curvature and current sheet drifts and the other basic modulation mechanisms. The model results are compared to the observed 11-year and 22-year cycles for 1.2 GV electrons and 1.2 GV Helium at Earth for the period 1975–1998. The model solutions are also compared to the observed charge-sign dependent modulation along Ulysses’ trajectory for the period 1990–1998. This compound approach to long-term modulation, especially charge-sign dependent modulation, is found to be remarkably successful. It is shown that the model can easily account for the latitude dependence for cosmic ray protons and the lack thereof for cosmic ray electrons by assuming large perpendicular diffusion in the polar direction. This approach contributes to an improved understanding of how diffusion and drifts vary from solar minimum to maximum modulation, and what the time-dependence of the heliospheric diffusion coefficients may be. Key words. Interplanetary physics (energetic particles; cosmic rays; general or miscellaneous)
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Milcíades Peña, Alejandro. "The political trajectory of the Brazilian CSR movement." critical perspectives on international business 10, no. 4 (September 30, 2014): 310–28. http://dx.doi.org/10.1108/cpoib-03-2014-0016.
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Purpose – This paper aims to examine the origins and trajectory of the Brazilian corporate social responsibility (CSR) movement in relation to political economic developments in Brazil during and prior to the 2000s. Design/methodology/approach – This paper relies on a historical political account that traces the evolution of the main actors in the CSR movement since the democratization period, details the contacts established with relevant political and civil society groups and outlines the adaptation of their agenda to the changing context. Findings – The long association between a faction of Brazilian business and the Workers’ Party (PT) and the overlapping state – society relations characteristic of the Brazilian political economy explain the domestic and international standing of the Brazilian CSR movement, in particular since 2003 when Lula da Silva came to power. Originality/value – The trajectory of Brazilian CSR and participation in related global initiatives cannot be explained through market-based or isomorphic approaches traditionally used to analyze the diffusion of governance mechanisms in the Global South. Rather, it highlights the relevance of local political structures in shaping involvement in global governance initiatives.
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Parra-Velásquez, Carolina, Darling Perea-Cabarcas, and Francisco Javier Bolivar-Osorio. "Effect of cobalt content on non-isothermal crystallization kinetics of Fe-based amorphous alloys." Revista Facultad de Ingeniería Universidad de Antioquia, no. 95 (December 10, 2019): 44–52. http://dx.doi.org/10.17533/10.17533/udea.redin.20190735.
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In the present study, FeSiBP and FeCoSiBP ribbons with a fully amorphous structure were made by melt spinning technique. A detailed analysis of the isochronal crystallization behavior is presented in this paper. The influence of cobalt on the crystallization kinetics of the alloys was studied under isochronal conditions using differential scanning calorimetry (DSC). Apparent and local activation energy values were determined by Kissinger, Ozawa and Kissinger-Akahira-Sunose (KAS) methods. The results indicate that appropriate amounts of cobalt can significantly enhance the thermal stability of Fe-based alloys, through an increase in nucleation activation energy from 538kJ/mol to 701kJ/mol, obtained by Kissinger method. Furthermore, with the method proposed by Matusita, it was possible to obtain global values for the Avrami exponent, noting that from a general perspective, Co changes the mechanism from diffusion controlled to interface controlled. This leads to the conclusion that the crystallization process is complex and takes place in more than one stage. Therefore, the determination of nucleation mechanisms and dimensional growth is difficult due to the inapplicability of the Johnson-Melh-Avrami (JMA) model. As such, a study under isothermal conditions is suggested, in order to achieve a full understanding of the mechanisms involved.