1,721,022 research outputs found
Innovation Diffusion Processes: Concepts, Models, and Predictions
Full text linkInnovation diffusion processes have attracted considerable research attention for their interdisciplinary character, which combines theories and concepts from disciplines such as mathematics, physics, statistics, social sciences, marketing, economics, and technological forecasting. The formal representation of innovation diffusion processes historically used epidemic models borrowed from biology, departing from the logistic equation, under the hypothesis that an innovation spreads in a social system through communication between people like an epidemic through contagion. This review integrates basic innovation diffusion models built upon the Bass model, primarily from the marketing literature, with a number of ideas from the epidemiological literature in order to offer a different perspective on innovation diffusion by focusing on critical diffusions, which are key for the progress of human communities. The article analyzes three key issues: barriers to diffusion, centrality of word-of-mouth, and the management of policy interventions to assist beneficial diffusions and to prevent harmful ones. We focus on deterministic innovation diffusion models described by ordinary differential equations
Diffusion of Renewable Energy for Electricity: An Analysis for Leading Countries
No full textMany countries are undertaking their energy transition process, by investing in renewable energy technologies, in order to face climate change and energy security problems. This paper investigates the temporal trends of the diffusion process of renewable energies, namely, wind and solar, in leading countries for their consumption. In doing so, a bivariate diffusion model is employed to investigate the possibly competitive dynamics between renewables and the top source for electricity production in each country. The obtained results confirm a significant competitive pressure enacted by renewables on the top source. A notable exception is represented by the USA, where renewables appear to reinforce the dominant position of gas
Optimal time-profiles of public health intervention to shape voluntary vaccination for childhood diseases
No full textIn order to seek the optimal time-profiles of public health systems (PHS) Intervention to favor vaccine propensity, we apply optimal control (OC) to a SIR model with voluntary vaccination and PHS intervention. We focus on short-term horizons, and on both continuous control strategies resulting from the forward-backward sweep deterministic algorithm, and piecewise-constant strategies (which are closer to the PHS way of working) investigated by the simulated annealing (SA) stochastic algorithm. For childhood diseases, where disease costs are much larger than vaccination costs, the OC solution sets at its maximum for most of the policy horizon, meaning that the PHS cannot further improve perceptions about the net benefit of immunization. Thus, the subsequent dynamics of vaccine uptake stems entirely from the declining perceived risk of infection (due to declining prevalence) which is communicated by direct contacts among parents, and unavoidably yields a future decline in vaccine uptake. We find that for relatively low communication costs, the piecewise control is close to the continuous control. For large communication costs the SA algorithm converges towards a non-monotone OC that can have oscillations
Endogenous age structure in descriptive macroeconomic growth models: a general framework and some steady states analysis
No full textCoordination games vs prisoner's dilemma in sustainability games: A critique of recent contributions and a discussion of policy implications
Full text linkRecent works have suggested that most games arising in climate change diplomacy and sustainability choices, should have a coordinative nature rather than that of a prisoners' dilemma, as typically suggested. In this note, after having proposed a definition of sustainability game, we critically review the merits and shortcomings of these contributions and use a simple, yet sufficiently general, model to recall the difficulties for coordination to emerge in such games. Indeed, as far as the players' short-term interest is involved, at least in some degree, these games will most often generate a prisoner's dilemma, thereby allowing coordination only upon long-term interactions possibly under the pressure of a continuing environmental deterioration. A counter- intuitive result is proved, showing the circumstances when the deterioration of the environment can hinder cooperation in repeated games. We conclude by highlighting a number of factors forcing “brown” behaviour and therefore threatening coordination, first of all poverty and inequality, and pinpointing that, though ability to enact coordination will be key for a successful battle for climate, undue emphasis on coordination might be the deleterious in view of its optimistic message
Multiple pandemic waves vs multi-period/multi-phasic epidemics: Global shape of the COVID-19 pandemic
No full textThe overall course of the COVID-19pandemic in Western countries has been characterized by complex sequences of phases. In the period before the arrival of vaccines, these phases were mainly due to the alternation between the strengthening/lifting of social distancing measures, with the aim to balance the
protection of health and that of the society as a whole. After the arrival of vaccines,this multi-phasic character was further emphasized by the complicated deployment of vaccination campaigns and the onset of virus’ variants.To cope with this multi-phasic character,we propose a theoretical approach to the modeling of overall
pandemic courses, that we term multi-period/multi phasic, based on a specific definition of phase.This allows a unified and parsimonious representation of complex epidemic courses even when vaccination and virus’ variants are considered, through sequences of weak ergodic renewal equations that become fully ergodic when
appropriate conditions are met. Specific hypotheses on epidemiological and intervention parameters allow reduction to simple models. The framework suggests a simple, theory driven,approach to data explanation that allows an accurate reproduction of the overall course of the COVID-19 epidemic in Italy since its beginning
(February2020) up to omicron onset, confirming thevalidity of the concept
Optimal social distancing in pandemic preparedness and lessons from COVID-19: Intervention intensity and infective travelers
No full textOur analysis seeks best social distancing strategies optimally balancing the direct costs of a threatening outbreak with its societal-level costs by investigating the effects of different levels of restrictions’ intensity and of the continued importation of infective travellers, while controlling for the key dimensions of the response, such as early action, adherence and the relative weight of societal costs. We identify two primary degrees of freedom in epidemic control, namely the maximum intensity of control measures and their duration. In the absence of travellers, a lower (higher) maximum intensity requires a longer (shorter) duration to achieve similar control outcomes. However, uncontrollable external factors, like the importation of undetected infectives, significantly constrain these degrees of freedom so that the optimal strategy results to be one with low/moderate intensity but prolonged in time. These findings underscore the necessity for resilient health systems and coordinated global responses in preparedness plans
Statistical inference for models of close-contact infection transmission. Validating varicella transmission
No full textWhat do adoption patterns of solar panels observed so far tell about governments’ incentive? Insights from diffusion models
No full textDiffusion of Solar PV Energy in Italy: Can Large-Scale PV Installations Trigger the Next Growth Phase?
Full text linkThe National Energy and Climate Plans (NECPs) of the EU Member States have established comprehensive goals for 2030 to speed up the process of energy transition. Though Italy was an innovator in the area of photovoltaics (PV) up until 2014, the subsequent collapse and stagnation of its PV market have revealed an intrinsic fragility, which makes reaching international targets in the future unclear. This study used the Generalized Bass Model in a multi-phase extension to offer insights into and perspectives on the Italian PV market with the use of new data at finer temporal and market-size scales. Our model-based evidence suggests the possibility of a remarkable structural change corresponding to the "reboot" period after the pandemic crisis. In this period, small- and large-scale PV adoption, after years of parallel pathways, have taken largely different routes. On the one hand, small-scale adoption exhibited a fast decline with the end of the post-COVID-19 incentive programs, thus confirming the traditional "addiction to incentive" issue. On the other hand, during the "reboot" period, large-scale installations showed, for the first time, symptoms of exponential growth. This is consistent with the possibility that, finally, this sector is on an autonomous growth path. The latter evidence might represent a critically important novelty in the Italian PV landscape, where firms-rather than households-take the lead in the process. Nonetheless, future public monitoring and guidance are both urgent requirements to avoid a further catastrophic fall in the residential PV market and to make the sustained growth of the large-scale PV industry a robust phenomenon
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