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Essays on Monetary Policy
Full text linkThis thesis consists of two independent chapters on monetary policy.Chapter 1 studies optimal monetary policy under imperfect credibility in a New Keynesian model with staggered price and wage setting. In our imperfect credibility framework, the central bank commits to a policy plan but occasionally reneges on past promises with a given common knowledge probability. We find that the welfare gains from increasing credibility are approximately linear on the initial credibility level. The variance decomposition shows that wage markup shocks are the main driver of economic fluctuations and that these shocks are better contained when credibility is high. We then show that the degree of credibility impacts the effect of wage flexibility on welfare. When credibility is low, monetary policy is less potent and the economy can experience a feedback loop between wage volatility and price volatility. We show, though, that once wage markup shocks are considered, wage flexibility is welfare improving.Chapter 2 examines the effects of higher inflation expectations on households' consumption plans. Higher inflation expectations can boost private consumption if the real interest rate decreases. However, households often report that they dislike high inflation due to the erosion of nominal income, and standard models often abstract from this channel. This chapter uses a dataset with quantitative expectations for both inflation and nominal interest rates, which allow us to determine consumption behavior both during normal times and zero lower bound (ZLB) periods. We find that higher inflation expectations encourage households to bring forward durable goods purchases while discouraging spending on non-durables. We show that these results are consistent with a model in which higher inflation expectations erode a household's permanent income thereby discouraging non-durable consumption, whereas durable consumption increases due to the lower real rate. Moreover, we analyze different counterfactuals and show that nominal wage expectations are central
How modelling can help steer the course set by the World Health Organization 2021-2030 roadmap on neglected tropical diseases
No full textEnhancing the resistance to H2S toxicity during anaerobic digestion of low-strength wastewater through granular activated carbon (GAC) addition
No full textLow-strength wastewater was treated using two laboratory-scale up-flow anaerobic sludge blankets (UASB) for 130 days under sulfate-reducing conditions. Granular activated carbon (GAC) was added to one of the reactors. The GAC addition increased the total chemical oxygen demand removal by 21% - 28% and total methane production by 32% - 78%. The sludge from the GAC-amended UASB showed higher specific methanogenic activities (SMA) and higher activities in the presence of H2S, indicating that the GAC addition enhanced the resistance of methanogens to H2S toxicity. Further, the microbial communities showed that the GAC addition shifted microbial communities. A robust syntrophic partnership between bacteria (i.e., Bacteroidetes_vadinHA17 and Trichococcus) and methanogens was established in the GAC-amended UASB. Sulfate-reducing bacteria (SRB) were enriched in the GAC biofilm, indicating the coexistence of competition and cooperation between SRB and methanogens. These findings provide significant insights regarding microbial community dynamics, especially SRB and methanogens, in a GAC-amended anaerobic digestion process under sulfate-reducing conditions
Open quantum dynamics for plant motions
Full text linkStochastic Schrödinger equations that govern the dynamics of open quantum systems are given by the equations for signal processing. In particular, the Brownian motion that drives the wave function of the system does not represent noise, but provides purely the arrival of new information. Thus the wave function is guided by the optimal signal detection about the conditions of the environments under noisy observations. This behaviour is similar to biological systems that detect environmental cues, process this information, and adapt to them optimally by minimising uncertainties about the conditions of their environments. It is postulated that information-processing capability is a fundamental law of nature, and hence that models describing open quantum systems can equally be applied to biological systems to model their dynamics. For illustration, simple stochastic models are considered to capture heliotropic and gravitropic motions of plants. The advantage of such dynamical models is that it allows for the quantification of information processed by the plants. By considering the consequence of information erasure, it is argued that biological systems can process environmental signals relatively close to the Landauer limit of computation, and that loss of information must lie at the heart of ageing in biological systems
Social Isolation in Older Adults: A Qualitative Study on the Social Dimensions of Group Outdoor Health Walks
Full text linkPhysical distancing practices during the COVID-19 global pandemic contributed to a high degree of social isolation among older adults. To reduce loneliness and other ill effects of social isolation, public health experts recommended outdoor social gathering, with physical distancing. Adopting a case study approach, we explored how social aspects of group outdoor health walks (GOHWs) mitigate social isolation for older adults and improve individual social wellbeing. We used semi-structured interviews to understand the experiences of social isolation and social relationships in nine older (50–80 s) adults participating in a GOHW in Scotland, United Kingdom (UK). Verbatim transcripts were analysed through an iterative process of thematic analysis carried out by an interdisciplinary team of qualitative researchers from environmental psychology, medicine, and geography. Themes provide insight into the social dimensions of GOHWs, the mediating effects of social experiences, and the contribution these make to individual social wellbeing. GOHWs provide opportunities to be part of a group and attend to the needs of inexperienced or physically challenged individuals. Being part of the group walk fosters casual interpersonal interactions through spontaneous mixing during and after the walk. This programmatic structure counters loneliness, engenders pleasurable anticipation of regular contact with others, supports physical activity, and fosters group cohesion. These in turn contribute to individual social wellbeing, including expanding social networks, meaningful relationships, a sense of belonging, and acting on empathy for others. GOWHs may be beneficial for mitigation of social isolation as we emerge from the COVID-19 pandemic. Findings were used to propose a conceptual model to parse social constructs and inform selection or development of quantitative social measures for future studies of nature-based interventions such as GOHWs
Simulating the complete pyrolysis and charring process of phenol-formaldehyde resins using reactive molecular dynamics
No full textWe examine the mechanism of pyrolysis and charring of large (> 10,000 atom) phenol-formaldehyde resin structures produced using pseudo-reaction curing techniques with formaldehyde/phenol ratios of 1.0, 1.5 and 2.0. We utilise Reactive Molecular Dynamics (RMD) with a hydrocarbon oxidation parameter set to simulate the high-temperature thermal decomposition of these resins at 1500, 2500 and 3500 K. Our results demonstrate that the periodic removal of volatile pyrolysis gasses from the simulation box allows us to achieve near complete carbonisation after only 2 ns of simulation time. The RMD simulations show that ring openings play a significantly larger role in thermal decomposition than has previously been reported. We also identify the major phases of phenolic pyrolysis and elucidate some of the possible mechanisms of fragment formation and graphitisation from the RMD trajectories and compute the thermal and mechanical properties of the final pyrolysed structures.[GRAPHICS]
Creativity in translation: machine translation as a constraint for literary texts
Full text linkThis article presents the results of a study involving the translation of ashort story by Kurt Vonnegut from English to Catalan and Dutch using threemodalities: machine-translation (MT), post-editing (PE) and translation withoutaid (HT). Our aim is to explore creativity, understood to involve novelty andacceptability, from a quantitative perspective. The results show that HT hasthe highest creativity score, followed by PE, and lastly, MT, and this isunanimous from all reviewers. A neural MT system trained on literary data doesnot currently have the necessary capabilities for a creative translation; itrenders literal solutions to translation problems. More importantly, using MTto post-edit raw output constrains the creativity of translators, resulting ina poorer translation often not fit for publication, according to experts
An authentication and key agreement scheme for smart grid
No full textThe Internet of Things (IoT) plays a crucial role in the new generation of smart cities, in which developing Internet of Energy (IoE) in the energy sector is a necessity also. Several schemes have been proposed so far and in this paper we analyze the security of a recently proposed authentication and key agreement framework for smart grid named PALK. Our security analysis demonstrates that an attacker can extract the user permanent identifier and password, which are enough to do any other attacks. To remedy the weaknesses and amend PALK, we propose an improved protocol based on Physical Unclonable Function(PUF) to provide desired security at a reasonable cost. We also prove the semantic security of constructed scheme by using the widely-accepted real and synthetic model, under the computationally hard Diffie-Hellman assumption. Computational and communication cost analysis of the improved protocol versus PALK, based on identical parameter sets on our experimental results on an Arduino UNO R3 board having microcontroller ATmega328P, shows 46% and 23% enhancements, respectively. We also provide, the energy consumption of the proposed protocol and each session of the protocol consumes almost 24 mJ energy. It shows that it is an appropriate choice for constrained environments, such as IoE
Energy System Optimization for Net-Zero Electricity
No full textA novel and fast-converging cost minimization model using non-linear constrained mathematical programming (NLP) has been developed to optimize renewable and bioenergy generation and storage systems’ capacities for transitioning to an electricity system with net-zero greenhouse gas emissions. Running this temporal and spatial multi-scale model gives an in-depth understanding of realistic electricity mixes in sustainable transitioning. The model comprises three interactive modules 1) analytics and visualization of data inputs, climatic and demand time-series, and design configurations, and output results, optimal electricity mix, and storage characteristics, 2) mathematical models of renewable generation systems using non-linear climate-dependent capacity factor time-series and energy system components, and 3) NLP to minimize the total cost. Hourly and total energy balances are the crucial constraints influencing the speed and efficacy of the solution. Fast-converged solutions of the NLP model are updated considering battery energy storage with a few hours dispatch time for attainable optimum net-zero electricity (NZE) mix. The NLP optimization model is tested on the energy-intensive UK South. The feasible optimum regional solutions characterized as high renewable supply-medium-to-high-demand (South West), low-supply-medium-demand (Greater London), and high-supply-high-demand (South East) scenarios are projected to the UK national level. The inputs to the NLP model are wind speed and solar radiation with annual hourly resolutions curated from the Centre for Environmental Data Analysis, process economic parameters (investment, fixed, operating, and resource costs, weighted average cost of capital, and life in years of processes) from the LUT energy system model, and global warming potential impacts from our archived literature. 2020-2050 electricity mixes are analyzed with varying costs and demands. The NLP optimization followed by energy storage feasibility analysis gives the following attainable optimal energy mixes: wind: 55%, solar: 29%, hydro: 0.5%, geothermal: 0.4%, and bioenergy: 1% (high-supply-medium-to-high-demand); wind: 52%, solar: 32%, hydro: 0.5%, geothermal: 0.5%, and bioenergy: 1% (low-supply-medium-demand); and wind: 45%, solar: 23%, hydro: 0.7%, geothermal: 0.7%, and bioenergy: 10% (high-supply-high-demand). Energy storage (13.5 TWh in the UK South) with 13-22% contributions of load demand (80 TWh in the UK South) costs 14% of the levelized cost of electricity production, 120-190 EURO/MWh. The high-supply-medium-to-high-demand scenario, providing the UK NZE projection of wind: 40GW, solar: 21GW, bioenergy and other renewables: 5GW, nuclear: 6GW, and gas with carbon capture, utilization, storage, and sequestration (CCUS): 5GW by 2050, mirrors the government's NZE plan. The additional wind (currently at 8.65GW), solar (currently at 1.5GW), and CCUS (currently there is none) capacities require £23 billion, £4 billion, and £1 billion investment costs
In-beam gamma-ray spectroscopy of 32Mg via direct reactions
Full text linkBackground: The nucleus 32Mg (N = 20 and Z = 12) plays a central role in the so-called "island of inversion," where in the ground states sd-shell neutrons are promoted to the fp-shell orbitals across the shell gap, resulting in the disappearance of the canonical neutron magic number N = 20. Purpose: The primary goals of this work are to extend the level scheme of 32Mg, provide spin-parity assignments to excited states, and discuss the microscopic structure of each state through comparisons with theoretical calculations. Method: In-beam gamma -ray spectroscopy of 32Mg was performed using two direct-reaction probes: one-neutron (two-proton) knockout reactions on 33Mg (34Si). Final-state exclusive cross sections and parallel momentum distributions were extracted from the experimental data and compared with eikonal-based reaction model calculations combined with shell-model overlap functions. Results: Owing to the remarkable selectivity of the one-neutron and two-proton knockout reactions, a significantly updated level scheme for 32Mg, which exhibits negative-parity intruder and positive-parity normal states, was constructed. The experimental results were confronted with four different nuclear structure models. Conclusions: In some of these models, different aspects of 32Mg and the transition into the island of inversion are well described. However, unexplained discrepancies remain, and, even with the help of these state-of-the-art theoretical approaches, the structure of this key nucleus is not yet fully captured
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