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Investigating the nature, drivers and sources of innovation in Africa, this book examines the channels for effective diffusion of innovation in and to Africa under institutional, resource and affordability constraints. Fu draws on almost a decade of research on innovation in Africa to explore these issues and unpack the process, combining a rigorous statistical analysis of a purposely designed multi-wave, multi-country survey with in-depth studies of representative cases. Building on this research, Fu argues that African firms are innovative but unsupported. Those 'under-the-radar' innovations that widely exist in Africa as a result of the constraints are not sufficient to enable Africa to leapfrog the innovation gap in the era of the fourth Industrial Revolution. This is the first comprehensive analysis of the creation and diffusion of innovation in low income countries. It also provides the first survey-based analysis of innovation in the informal economy.
Thin films of platinum deposited by physical vapor deposition (PVD) processes such as evaporation and sputtering are used in many academic and industrial settings, for example to provide metallization when tolerance to corrosive thermal cycling is desired, or in electrocatalysis research. In this review, various practical considerations for platinum (Pt) metallization on both Si and SiO2 are placed in context with a comprehensive data review of diffusion measurements. The relevance of diffusion phenomena to the development of microstructure during deposition as well as the effect of microstructure on the properties of deposited films are discussed with respect to the Pt–Si system. Since Pt and Si readily form silicides, diffusion barriers are essential components of Pt metallization on Si, and various failure modes for diffusion barriers between Pt and Si are clarified with images obtained by electron microscopy. Adhesion layers for Pt films deposited on SiO2 are also considered.
High-entropy alloys (HEAs) are proposed as potential structural materials for advanced nuclear systems, but little is known about the response of matrix chemistry in HEAs upon irradiation. Here, we reveal a substantial change of matrix chemical concentration as a function of irradiation damage (depth) in equiatomic NiCoFeCr HEA irradiated by 3 MeV Ni ions. After ion irradiation, the matrix contains more Fe/Cr in depth shallower than ~900–1000 nm but more Ni/Co from ~900–1000 nm to the end of the ion-damaged region due to the preferential diffusion of vacancies through Fe/Cr. Preferential diffusion also facilitates migration of vacancies from high radiation damage region to low radiation damage region, leading to no void formation below ~900–1000 nm and void formation around the end of the ion-damaged region at a fluence of 5 × 1016 cm−2 (~123 dpa, displacements per atom, peak dose under full cascade mode). As voids grow significantly at an increased fluence (8 × 1016 cm−2, 196 dpa), the matrix concentration does not change dramatically due to new voids formed below ~900–1000 nm.
Do states copy or reinvent language from complex policies as they diffuse, and does this depend on legislative resources? We argue that states will more frequently reinvent more complex policies, but that states with high-resource legislatures will reinvent more than their low-resource counterparts for more complex policies. We test the theory using the bill texts from 18 policies that diffused across the 50 states from 1983 to 2014, measuring reinvention and complexity using text analysis tools. In line with expectations, we find that complex policies are reinvented more than simple policies and that high-resource legislatures reinvent bills more than low-resource legislatures on average. However, we also find that low-resource legislatures reinvent complex policies at about the same rate as high-resource legislatures. The results indicate that even legislatures with limited resources work to adapt complex policies during the diffusion process.
This chapter reviews the spread of irrigation technology across the Sahara in antiquity, and its effects on settlement agriculture and the movement of people. Recent work has stressed the close connections between the introduction of foggara technology and the rise of Garamantian civilisation, which featured intensive agriculture and incipient urbanism. However, many oases achieved substantial size through the use of well technologies, artesian springs or a combination of technologies. Another key question relates to the effects of the eventual decline and failure of these irrigation systems in terms of population movement and fragmentation of states such as the Garamantes. After presenting new AMS dating evidence for Garamantian foggaras, the chapter advances the discussion by examining the wider picture of foggara distribution within a survey of the evidence of irrigation technologies across the Sahara and whether and to what extent the distribution of foggaras beyond the core Garamantian heartlands might be seen as an indication of Garamantian control or influence. It explores what foggaras, wells and new crop introductions might suggest about agricultural intensification and organisation. This has implications for assessing agricultural intensification in the ancient Sahara. Finally, it considers causes and possible effects of irrigation failure and in some cases collapse.
The popular image of the Sahara Desert as something unchanging through time (oases with wells and palm-trees, interconnected by caravans of dromedaries and Tuareg Bedouins) is obviously contradicted by the evidence coming from the archaeological discoveries, and a long-term (and rather slow) process of technological change can be outlined – albeit in need of additional and more precise information. Local innovations, originating in the (Central) Saharan area itself are by no means to be underestimated. Also stimuli coming from the Mediterranean area and from the Nile valley prove quite important (also in the realm of socio-political organisation). However, several innovations in the basic realms of agriculture, animal husbandry and irrigation technology appear to have originated in the East Arabian area (Oman and surrounding countries), and to have been adopted in the Central Sahara only later, in some cases much later. The entire desert belt – from the Gulf area to the Atlantic shores – functioned as a kind of corridor for the east to west transfer of technologies especially appropriate to the hyper-arid climate.
Scholars have generally taken a “diffusionist” view of the rise of national standard languages—the state pushes for the wider adoption of such languages, and other forces (principally economic modernization) facilitate its diffusion. But such a view is too mechanistic and Eurocentric, and an examination of other, less-familiar cases lends itself to a revised interpretation. Amid Western imperialism and the rise of nationalism in East Asia in the late 19th and early 20th centuries, a massive shift in language practices took place between about 1870 and 1950, as regional hegemony shifted from China to Japan. Bound for two millennia by their common use of Classical Chinese, elite literati in China, Korea, Japan, and Vietnam all moved away from that abstruse lingua franca and turned to the creation of new national vernaculars. I argue for a more “integrationist” perspective: language nationalization was a state-led and top-down process directed at remaking society.
Kinetic theory is a framework for calculating macroscopic physical properties of systems from their microscopic degrees of freedom. This idea is applied to an ideal gas to derive the Maxwell--Boltzmann velocity distribution, which is demonstrated to be compatible with the ideal gas law and is used to calculate the rate of effusion of an ideal gas. When molecular collisions are important, the mean free path and collision time are quantities that can characterize these collisions. Situations in which collisions are important, such as Brownian motion and diffusion, are presented, along with relevant equations: the Langevin equation and Fick's Law.
The observations and simulations have revealed that large-scale magnetic field and outflows can exist in the inner regions of an advection-dominated accretion disc where the resistive diffusion may also be important. In the present paper, the roles of large-scale magnetic field and outflows in the structure of resistive advection-dominated accretion discs are explored by assuming that the accretion flow is radially self-similar. In the non-ideal magnetohydrodynamic (MHD) approximation, the results show that the angular velocity is always sub-Keplerian when both the outflow and the large-scale magnetic field are taken into account. A stronger toroidal field component leads to faster rotation, while the disc rotates with faster rate if the vertical field component is weaker. The increase of magnetic diffusivity causes the infall velocity to be close to Keplerian velocity. Although the previous studies in the ideal MHD approximation have shown that the disc temperature decreases due to the vertical field component, we find that the effect of vertical field component on the temperature of a resistive disc depends on the magnetic diffusivity. When the magnetic diffusivity is high, the more efficient mechanism for decreasing the disc temperature can be the outflows, and not the large-scale magnetic field. In such a limit of the magnetic diffusivity, the components of the large-scale magnetic field enhance the gas temperature. The increase of temperature can lead to heating and acceleration of the electrons and help us to explain the origin of phenomena such as the flares in Sgr A*. On the other hand, the infall velocity in such a limit rises as the temperature increases, and therefore the surface density falls to too low values. Any change in the density profile can alter the structure and the emitted spectrum of disc.
Why is the #MeToo movement very active in some countries but not in others? What factors encourage the transnational diffusion of digital feminist activism? Although transnational forces are important, we argue that domestic political opportunity structures play a more significant role than transnational influences in the country-level diffusion of #MeToo. We collected 35,211 global tweets and used Bayesian statistical modeling to test the implications of our theory. Our findings support the idea that as a country better protects its citizens’ political and civil rights and civil liberties, individuals in that country are more likely to engage in the #MeToo movement.
Chapter 3 begins by describing mechanisms of atomic diffusion in crystals, with emphasis on how their rates depend on temperature. Characteristic diffusion lengths and times are explained. The diffusion equation is derived for the chemical composition in space and time, c(r,t). The mathematics for solving the diffusion equation in one dimension are developed by standard approaches with Gaussian functions and error functions. The method of separation of variables is presented for three-dimensional problems in Cartesian and cylindrical coordinates. Typical boundary value problems for diffusion are solved with Fourier series and Bessel functions.
Part of the allure of Jessup’s description of transnational law undoubtedly lies in its promise of capturing something beyond the most visible aspects of public and private international law – in its invocation to uncover ‘unseen law’, including law that is important in practice but neglected in scholarship. Transnational law, whether viewed substantively or as a methodological approach, expands law’s vision field. Yet the task of making visible the actualities of law and practice comprising transnational law involves slippery methodological questions that legal scholars seem particularly skilled at sidestepping. This short chapter examines the intellectual holding pen created by Jessup for other rules and sources of law, his ‘larger storehouse of rules’. It interrogates the meaning of the practice-enriched perspective that transnational law claims to deliver, arguing that those who invoke practice in fact mean many different things. Finally, the chapter considers the twin research challenges of selective vision and partial knowledge, identifying four ‘black boxes’ that might inspire new directions in transnational environmental law research.
Regarding the effect of composition on the mechanical properties of intermetallic phases such as Laves phases, there is conflicting information in the literature. Some authors observed defect hardening when deviating from stoichiometric Laves phase composition, whereas others find defect softening. Here, we present a systematic investigation of the defect state, hardness, and elastic modulus of cubic and hexagonal NbCo2 Laves phases as a function of crystal structure and composition. For this purpose, diffusion couples were prepared which exhibit diffusion layers of the cubic C15 and hexagonal C14 and C36 NbCo2 Laves phases, with concentration gradients covering their entire homogeneity ranges from 24 to 37 at.% Nb. Direct observations of dislocations and stacking faults in the diffusion layers as a function of composition were performed by electron channeling contrast imaging, and the hardness and elastic modulus were probed in the diffusion layers along the concentration gradients by nanoindentation.
For the first time in the literature, experimental determination of entire sets of exact interdiffusion coefficients in quaternary and quinary alloy systems is reported. Using the method of body-diagonal diffusion couple, a set of nine quaternary interdiffusion coefficients were evaluated in Fe–Ni–Co–Cr and a set of sixteen quinary interdiffusion coefficients were determined in a Fe–Ni–Co–Cr–Mn system, both at approximately equimolar compositions. Regions of uphill interdiffusion and zero flux planes were observed for nickel and cobalt in quinary couples, indicating the existence of strong diffusional interactions in Fe–Ni–Co–Cr–Mn alloys. The strong diffusional interactions were also manifested in the large magnitudes of cross coefficients in both the systems. The existence of strong diffusional interactions in high-entropy alloys (HEAs) as observed through experimentally determined interdiffusion coefficients in this study establishes beyond doubt the fact that cross interdiffusion coefficients cannot be ignored in HEAs.
In this paper, we develop and empirically test hypotheses about the diffusion of imported management practices in Turkey. We emphasize the sociopolitical legitimacy of these practices and present hypotheses as to timing, motivations, and self-promotion. We test these hypotheses with quantitative data on Total Quality Management (TQM) adoption by industrial companies in Turkey. Findings reveal that elite companies adopt TQM earlier on, self-report greater levels of sociopolitically driven legitimacy concerns, and are more likely to participate in a prestigious quality award contest. Overall, our study contributes to diffusion research guided by the new institutional approach by expanding existing models to the diffusion of imported practices across organizations in late-industrializing recipient countries. We particularly show that sociopolitical legitimacy of imported practices that is more characteristic of late-industrializing recipient contexts may generate a divergent pattern of diffusion whereby elite organizations emerge as early adopters and engage in brandishing adoption.
Each species is subject to various biotic and abiotic factors during growth. This paper formulates a deterministic model with the consideration of various factors regulating population growth such as age-dependent birth and death rates, spatial movements, seasonal variations, intra-specific competition and time-varying maturation simultaneously. The model takes the form of two coupled reaction–diffusion equations with time-dependent delays, which bring novel challenges to the theoretical analysis. Then, the model is analysed when competition among immatures is neglected, in which situation one equation for the adult population density is decoupled. The basic reproduction number
is defined and shown to determine the global attractivity of either the zero equilibrium (when
) or a positive periodic solution (
) by using the dynamical system approach on an appropriate phase space. When the immature intra-specific competition is included and the immature diffusion rate is neglected, the model is neither cooperative nor reducible to a single equation. In this case, the threshold dynamics about the population extinction and uniform persistence are established by using the newly defined basic reproduction number
as a threshold index. Furthermore, numerical simulations are implemented on the population growth of two different species for two different cases to validate the analytic results.
Rooted in historical linguistics, variationist sociolinguistics is often concerned with diachrony as reflected in synchronic grammars. World Englishes (WEs), which emerge through particular sociohistorical factors (e.g. colonialization, language contact, mass migration, dialect mixing, etc.), provide an ideal window for examining questions that are central to this mission: the inheritance of shared features, ongoing evolutionary mechanisms, and pathways of innovation as dialects interact and settle within new local linguistic ecologies. These varieties thus extend our knowledge base concerning the underlying mechanisms of language variation and change. In so doing, they enable theoretical and empirical advances through application of the comparative method, exposing the interaction between external social forces and internal linguistic ones on linguist forms and functions. In this chapter, I review variationist research that targets multiple varieties, both in the Inner Circle and, where available, the Outer Circle, to outline the gains that are possible by harnessing the synergistic energies of WEs through a variationist lens.
Copper is a candidate for use as an overpack material in deep underground nuclear waste disposal. Copper, however, is susceptible to corrosion following closure of the repository and migration of the corrosion products through the buffer material may affect the migration of redox-sensitive radionuclides. Electromigration experiments were performed whereby a copper coupon, which was in contact with compacted bentonite, served as the working electrode and was held at a constant potential of between +100 to +400 mV vs. Ag/AgCl electrode for up to 48 h. The amounts of copper that migrated into the bentonite specimens were found to be in good agreement with the calculated values based on the corrosion current flow for the assumption that copper underwent anodic dissolution as Cu(II). A model based on dispersion and electromigration was able to explain the measured copper profiles in the bentonite specimens. The fitted values of the dispersion coefficient did not depend on the applied potential and were about 10-12 m2/s.
The ‘farming/language dispersal hypothesis’ was originally developed to explain the spread of the Neolithic economy and material culture into Europe. Recently, this hypothesis has been applied towards explaining the dispersal and divergence of East Asian languages. However, interpretations depend on what prehistoric cultivar is chosen by linguists as having been related with the spread of language. In understanding the appearance of the proto-Koreanic and proto-Japonic languages in Korea, millet and rice, which appeared in Korea around 3500 and 1300 BCE, respectively, have been emphasized by linguists. We assess these linguistic arguments. We first review how European archaeologists have understood the spread of farming into Europe, where the farming/language dispersal hypothesis was originally developed, and how archaeology has wrestled with the issues of diffusion and migration. Then we move on to evaluating linguistic hypotheses about the dispersal and split of proto-Koreanic and proto-Japonic. Our evaluation of the ‘millet hypothesis’ and the ‘rice hypothesis’ suggests that rice is a more plausible candidate for explaining the dispersal of proto-Koreanic to Korea. Meanwhile, viewing the introduction of slender daggers to Korea as another dispersal of language to Korea needs more scrutiny.
In techniques such as Dynamic Light Scattering (DLS), Fluorescence Correlation Spectroscopy, and image mining, motion is tracked by the autocorrelation of a signal over logarithmic time scales. For instance the tracking signal in DLS is the scattered light intensity; it remains correlated at time scales where scant changes in the arrangement of the scattering particles occur, but decays exponentially at the time scales of their diffusion. When there are multiple time scales of motion (for instance due to scatterers of different sizes), the correlation curve has more than one exponential fall. Extracting the decay constants or hydrodynamic sizes due to each exponential fall in a multi-species field correlation curve becomes an ill-conditioned mathematical problem. We describe a new algorithm to invert a multi-modal correlation curve by Sequential Extraction of the Late Exponentials (SELE). The idea is that while the inversion of a multi-exponential equation may be ill posed, that of a single exponential is not. So we fit data windows towards to base of the correlation curve to extract the largest contribution species, remove the species contribution from the correlation curve, and repeat the process with the remnant curve. The single exponent can be robustly fitted by least-square minimization with initial guesses generated by an adapted cumutant technique (power-series) that includes stretch coefficients (measure of sample dispersity). The proposed algorithm resolves particle sizes separated by 3X, and is reliable against fluctuations in the correlation curve and to localized regions of suboptimal data. The algorithm can be used to track particle dynamics in solution in multi-species problems such as self-assembly.