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For the Environment: An Assessment of Recent Military Intervention in Informal Gold Mining Communities in Ghana
Get PDFThis article reflects critically on the impacts of the recent ban on artisanal and small-scale mining (ASM) โ low-tech, labour-intensive mineral extraction and processing โ in Ghana. Government officials claimed that a ban was necessary because the countryโs ASM activities, most of which are found in the informal economy, pose a serious threat to local waterbodies and that security forces were needed for its enforcement. It is argued here, however, that projecting the ban and associated military intervention as actions taken specifically to protect the environment has helped the government escape scrutiny over its choice of strategy to combat illegal mining. Perhaps more importantly, it has masked what may be the real reasons behind these moves: 1) to help the government regain control of the purchasing side of an ASM sector that is now heavily populated and influenced by foreigners; and 2) to put it in an improved position to demarcate parcels of land to the multinational mineral exploration and mining companies that supply it with significant quantities of revenue in the form of taxes, royalties and permit fees
A Novel Robust Network Data Envelopment Analysis Approach for Performance Assessment of Mutual Funds under Uncertainty
No full textMutual fund (MF) is one of the applicable and popular tools in investment market. The aim of this paper is to propose an approach for performance evaluation of mutual fund by considering internal structure and financial data uncertainty. To reach this goal, the robust network data envelopment analysis (RNDEA) is presented for extended two-stage structure. In the RNDEA method, leader-follower (non-cooperative game) and robust optimization approaches are applied in order to modeling network data envelopment analysis (NDEA) and dealing with uncertainty, respectively. The proposed RNDEA approach is implemented for performance assessment of 15 mutual funds. Illustrative results show that presented method is applicable and effective for performance evaluation and ranking of MFs in the presence of uncertain data. Also, the results reveal that the discriminatory power of robust NDEA approach is more than the discriminatory power of deterministic NDEA models
Lumped kinetic modelling of polyolefin pyrolysis: A non-isothermal method to estimate rate constants
No full textThe measurement of kinetic parameters in the pyrolysis of polyolefins requires the use of a lumped kinetic model for predicting the product distribution of wax, oil and gas yields. A non-isothermal method was established, in which a sample is heated in a tube reactor to a desired temperature at a constant rate of temperature rise. This method avoided the error present in the heating up stage which is inherent in any practical isothermal method in which reaction proceeds to a significant extent before the operating temperatures of polyolefin pyrolysis are reached, which results in challenges when defining the reaction time. The non-isothermal measurements were conducted between 450 and 550ยฐC for polypropylene (PP) and polyethylene (HDPE and LDPE) and the temperature and lump yields are non-linearly regressed to achieve the kinetic parameters. The measured kinetic rate constants have the same trend as those reported in the literature using the isothermal method, but are higher than the values reported above 450ยฐC and similar to the values for lower temperatures of 350ยฐC and 370ยฐC. The kinetic parameters derived are then validated by using isothermal experimental data. The calculated data using the measured kinetic parameters are generally in agreement with the experimental data. The non-isothermal method established in this work proves to be a much faster method for the measurement of intrinsic rate constants at high temperatures
A global perspective of the current state of heavy metals contamination in road dust
Get PDF16 Heavy metals are persistent and bio-accumulative, and pose potential risk to human health and 17 ecosystem. We reviewed the current state of heavy metals contamination, the ecotoxicological 18 and human health risk of heavy metals reported in urban road dust from various cities in different 19 continents (Asia, Europe, Africa, America, and Australia). We compared and synthesized the 20 findings on the methods related to sample collection, extraction, analytical tools of heavy metals, 21 their concentrations, level of contamination, ecological risk, non-carcinogenic risk, and 22 carcinogenic risk in road dust. Concentrations of Pb, Zn, Cu, Ni, Cd, Cr, Mn, and Fe were found 23 to be higher than their background values in soil. As expected, the contamination levels of the 24 heavy metals varied extensively among cities, countries, continents, and periods. A high level of 25 contamination is observed for Pb and Cd in road dust due to operating leaded gasoline and the old 26 vehicle population. The highest Zn contamination was observed from road dust in Europe, 27 followed by Asia, Africa, Australia, and America (North America and South America). Cu 28 contamination and the pollution load index (PLI) is found to be the highest in Europe and lowest 29 in Africa, with in-between values of PLI in American and African cities. The potential ecological 30 risk on different continents was observed highest in Asia, followed by Europe, Australia, America, 31 and Africa. A comparative assessment of non-carcinogenic risk for children indicated that 32 Australia is a most susceptible country due to high heavy metals exposure in road dust, followed 33 by Asia. However, there is no susceptible risk in European, African and American cities. We did 34 not observe any potential risk to adults due to non-carcinogenic metals. Carcinogenic risk to all 35 age groups was within the threshold limit range for all the regions worldwide. 3
Risk, uncertainty and ambiguity amid COVID-19: A multi-national analysis of international travel intentions
No full textThis study analyses how Covid-19 shapes individualsโ international tourism intentions in context of bounded rationality. It provides a novel analysis of risk which is disaggregated into tolerance/aversion of and competence to manage risks across three different aspects: general, domain (tourism) and situational (Covid-19). The impacts of risk are also differentiated from uncertainty and ambiguity. The empirical study is based on large samples (total=8,962) collected from the worldโs top five tourism source markets: China, USA, Germany, UK and France. Various risk factors show significant predictive powers of individualโs intentions to defer international tourism plans amid Covid-19. Uncertainty and ambiguity intolerance is shown to lead to intentions to take holidays relatively sooner rather than delaying the holiday plans. </p
Feasibility of an automated interview grounded in Multiple Mini Interview (MMI) methodology for selection into the health professions: an international multi-methods evaluation
Get PDFObjectives: Global, Covid-driven restrictions around face-to-face interviews for healthcare student selection have forced admissions staff to rapidly adopt adapted online systems before supporting evidence is available. We have developed, what we believe is, the first automated interview grounded in Multiple Mini-Interview (MMI) methodology. This study aimed to explore test re-test reliability, acceptability, and usability of the system.Design, setting and participants: Multi-method feasibility study in Physician Associate (PA) programmes from two UK and one US university during 2019 - 2020.Primary, secondary outcomes: Feasibility measures (test-retest reliability acceptability and usability) were assessed using intra-class correlation (ICC), descriptive statistics, thematic and content analysis.Methods: Volunteers took (T1), then repeated (T2), the automated MMI, with a seven-day interval (+/- 2) then completed an evaluation questionnaire. Admissions staff participated in focus group discussions.Results: Sixty-two students and seven admission staff participated; 34 students and four staff from UK and 28 students and three staff from US universities.Good-excellent test-retest reliability was observed with T1 and T2 ICC between 0.62-0.81 (p<0.001) when assessed by individual total scores (range 80.6-119), station total scores 0.6-0.91, p<0.005, individual site (all ICCโฅ 0.76 p<0.001) and mean test retest across sites 0.82 p<0.001 (95% CI 0.7-0.9).Admissions staff reported potential to reduce resource costs and bias through a more objective screening tool for pre-selection or to replace some MMI stations in a โhybrid modelโ. Maintaining human interaction through โtouch pointsโ was considered essential.Users positively evaluated the system, stating it was intuitive with an accessible interface. Concepts chosen for dynamic probing needed to be appropriately tailored.Conclusion: These preliminary findings suggest that the system is reliable, generating consistent scores for candidates and is acceptable to end-users provided human touchpoints are maintained. Thus, there is evidence for the potential of such an automated system to augment healthcare student selection.Strengths and limitations of this studyโข The underpinning iterative theoretical approach enabled a responsive, dynamic design and development process for a new technology with no known precedent.โข The conceptual leap from face-to-face or videoconference facilitated MMIs to a fully automated interview and assessment system may present barriers to stakeholders irrespective of the technology and itsโ features.โข The multi-method design provided for a diverse set of insights which have been essential to informing the progression of the technology.โข We were unable to assess for potential differential performance within sub-groups, as would require a larger sample size
Quantum Annealing for Next-Generation MU-MIMO Detection: Evaluation and Challenges
Get PDFยฉ 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Anaerobic digestion of untreated and treated process water from the hydrothermal carbonisation of spent coffee grounds
No full textThis study investigates the long-term performance of the mesophilic (35ย ยฐC) anaerobic mono-digestion of process waters (PW) from the hydrothermal carbonisation (HTC) of spent coffee grounds. At an organic loading rate (OLR) of 0.4 gCOD Lโ1 dโ1, initial instability was seen, but after 40 days and supplementary alkalinity, the digestion stabilised with the chemical oxygen demand (COD) in the untreated PW degraded with 37.8โ64.6% efficiency and the yield of methane at 0.16ย L gCODโ1. An increase in OLR to 0.8 gCOD Lโ1 dโ1 caused a collapse in biogas production, and resulted in severe instability in the reactor, characterised by falling pH and an increasing volatile fatty acid concentration. Comparatively, the digestion of a treated PW (concentrated in nanofiltration and reverse osmosis after removal of the fouling fraction), at OLR between 0.4 and 0.8 gCOD Lโ1 dโ1, was stable over the entire 117 days of treated PW addition, yielded methane at 0.21ย L gCODโ1 and the COD was degraded with an average efficiency of 93.5% - the highest efficiency the authors have seen for HTC PW. Further anaerobic digestion of untreated PW at an average OLR of 0.95 gCOD Lโ1 dโ1 was stable for 38 days, with an average COD degradation of 69.6%, and methane production between 0.15 and 0.19ย L gCODโ1. The digestion of treated PW produced significantly higher COD degradation and methane yield than untreated PW, which is likely to be related to the removal of refractory and inhibitory organic material in the post-HTC treatment by adsorption of hydrophobic material
Co-creacion de innovaciones orientadas a la sostenibilidad turistica en Barcelona
Get PDFThis report is a policy briefing containing the main findings of the PhD project Co-Creation of Sustainability-Oriented Innovations (SOIs) in Tourism. This project was conducted in close partnership with the Barcelona City Council to co-design institutional innovations to address sustainability challenges in the city by widely engaging stakeholders in a participatory process. To enable an open participatory process, the project was nested in the Consell de Turisme i Ciutat, which gathers key public, private and civil society organizations to discuss the main tourism development issues in the city of Barcelona. The project gathers data by conducting individual interviews, and a series of stakeholder workshops to better understand the complexity of designing SOIs collectively. Amongst the main findings, this report identifies how individual and collective conceptual nuances of innovation and sustainability affect the stakeholders' ability to embark on sustainability innovations in tourism. Further, it describes collective objectives, drivers and barriers that stakeholders identified when developing SOIs. The report also offers an analysis of current tourism specific and non-tourism SOIs in Barcelona and potential ways in which these existing SOIs could be leveraged to facilitate systemic change. One of the key findings of the study is a collection of co-created SOIs by the stakeholders, which are analysed in terms of their sustainability impact and their type of innovation. These SOIs include a wide range of policy actions and interventions related to management, product development and marketing, education, incentives and monitoring and evaluation. Amongst these SOIs, during the project, the stakeholders decided to focus on expanding on four SOIs which could have a greater potential to create systemic change in the sustainable development of the city and thus in the tourism sector. These four SOIs are presented in this report as one-page business plans to facilitate its potential application. Finally, the study provides a series of recommendations to enhance collaboration and governance mechanisms to allow SOIs to thrive as collective actions that are powered by legitimacy, trust and a fair distribution of power. In this line, to empower stakeholders to utilize the findings of this project the report introduces the idea of creating a Sustainability Innovation LivingLab.</p
Trajectory design of Earth-enabled Sun occultation missions
Get PDFUnderstanding the solar corona and its structure, evolution and composition can provide new insights regarding the processes that control the transport of energy throughout the solar atmosphere and out into the heliosphere. However, the visible emission coming from the corona is more than a million times weaker than the emission from the photosphere, implying that direct corona observations are only possible when the disk of the Sun is fully obscured. In this paper we perform a feasibility study of a Sun occultation mission using the Earth as a natural occulter. The challenge is that the occultation zone created by the Earth does not follow a Keplerian trajectory, causing satellites placed in this region to quickly drift away from eclipse conditions. To increase the number of revisits while optimizing the propellant budget, we propose optimal trajectories in the SunโEarth-Spacecraft circular restricted three body problem that account for scientific and engineering constraints such as limited power budget and mission duration. Chemical propulsion, electric propulsion and solar sailing configurations are compared in terms of performance and mission feasibility, revealing how 24 h of corona observations would be possible every 39 days with as little as 199 m/s of รญ ยตรญยปยฅรญ ยตรญยฑ\u89. The feasibility of the solar sail approach is hereby demonstrated, making it a challenging engineering alternative to currently available technologies
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