192 results on '"Nikas A"'
Search Results
2. Diagnostic challenges during inflammation and cancer : current biomarkers and future perspectives in navigating through the minefield of reactive versus dysplastic and cancerous lesions in the digestive system
- Author
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Pateras, Ioannis S., Igea, Ana, Nikas, Ilias P., Leventakou, Danai, Koufopoulos, Nektarios I., Ieronimaki, Argyro Ioanna, Bergonzini, Anna, Ryu, Han Suk, Chatzigeorgiou, Antonios, Frisan, Teresa, Kittas, Christos, Panayiotides, Ioannis G., Pateras, Ioannis S., Igea, Ana, Nikas, Ilias P., Leventakou, Danai, Koufopoulos, Nektarios I., Ieronimaki, Argyro Ioanna, Bergonzini, Anna, Ryu, Han Suk, Chatzigeorgiou, Antonios, Frisan, Teresa, Kittas, Christos, and Panayiotides, Ioannis G.
- Abstract
In the setting of pronounced inflammation, changes in the epithelium may overlap with neoplasia, often rendering it impossible to establish a diagnosis with certainty in daily clinical practice. Here, we discuss the underlying molecular mechanisms driving tissue response during persistent inflammatory signaling along with the potential association with cancer in the gastrointestinal tract, pancreas, extrahepatic bile ducts, and liver. We highlight the histopathological challenges encountered in the diagnosis of chronic inflammation in routine practice and pinpoint tissue-based biomarkers that could complement morphology to differentiate reactive from dysplastic or cancerous lesions. We refer to the advantages and limitations of existing biomarkers employing immunohistochemistry and point to promising new markers, including the generation of novel antibodies targeting mutant proteins, miRNAs, and array assays. Advancements in experimental models, including mouse and 3D models, have improved our understanding of tissue response. The integration of digital pathology along with artificial intelligence may also complement routine visual inspections. Navigating through tissue responses in various chronic inflammatory contexts will help us develop novel and reliable biomarkers that will improve diagnostic decisions and ultimately patient treatment.
- Published
- 2024
- Full Text
- View/download PDF
3. Advancing participatory energy systems modelling
- Author
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McGookin, Connor, Süsser, Diana, Xexakis, Georgios, Trutnevyte, Evelina, McDowall, Will, Nikas, Alexandros, Koasidis, Konstantinos, Few, Sheridan, Andersen, Per Dannemand, Demski, Christina, Fortes, Patrícia, Simões, Sofia G., Bishop, Christopher, Rogan, Fionn, Gallachóir, Brian Ó., McGookin, Connor, Süsser, Diana, Xexakis, Georgios, Trutnevyte, Evelina, McDowall, Will, Nikas, Alexandros, Koasidis, Konstantinos, Few, Sheridan, Andersen, Per Dannemand, Demski, Christina, Fortes, Patrícia, Simões, Sofia G., Bishop, Christopher, Rogan, Fionn, and Gallachóir, Brian Ó.
- Abstract
Energy system models are important tools to guide our understanding of current and future carbon dioxide emissions as well as to inform strategies for emissions reduction. These models offer a vital evidence base that increasingly underpins energy and climate policies in many countries. In light of this important role in policy formation, there is growing interest in, and demands for, energy modellers to integrate more diverse perspectives on possible and preferred futures into the modelling process. The main purpose of this is to ensure that the resultant policy decisions are both fairer and better reflect people's concerns and preferences. However, while there has been a focus in the literature on efforts to bring societal dimensions into modelling tools, there remains a limited number of examples of well-structured participatory energy systems modelling processes and no available how-to guidance. This paper addresses this gap by providing good practice guidance for integrating stakeholder and public involvement in energy systems modelling based on the reflections of a diverse range of experts from this emergent field. The framework outlined in this paper offers multiple entry points for modellers to incorporate participatory elements either throughout the process or in individual stages. Recognising the messiness of both fields (energy systems modelling and participatory research), the good practice principles are not comprehensive or set in stone, but rather pose important questions to steer this process. Finally, the reflections on key issues provide a summary of the crucial challenges and important areas for future research in this critical field.
- Published
- 2024
4. Three different directions in which the European Union could replace Russian natural gas
- Author
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Nikas, A., Frilingou, N., Heussaff, C., Fragkos, P., Mittal, S., Sampedro, J., Giarola, S., Sasse, J.P., Rinaldi, L., Doukas, H., Gambhir, A., Giannousakis, A., Golinucci, N., Koasidis, K., Rocco, M.V., Trutnevyte, E., Xexakis, G., Zachmann, G., Zisarou, E., Colombo, E., Hawkes, A., Yarlagadda, B., Binsted, M., Iyer, G., Johannsen, R.M., Thellufsen, J.Z., Lund, H., Van de Ven, D.J., Nikas, A., Frilingou, N., Heussaff, C., Fragkos, P., Mittal, S., Sampedro, J., Giarola, S., Sasse, J.P., Rinaldi, L., Doukas, H., Gambhir, A., Giannousakis, A., Golinucci, N., Koasidis, K., Rocco, M.V., Trutnevyte, E., Xexakis, G., Zachmann, G., Zisarou, E., Colombo, E., Hawkes, A., Yarlagadda, B., Binsted, M., Iyer, G., Johannsen, R.M., Thellufsen, J.Z., Lund, H., and Van de Ven, D.J.
- Abstract
Russia's invasion of Ukraine fuelled an energy crisis, which considerably impacted Europe given its heavy reliance on Russian natural gas imports. This study uses an ensemble of four global integrated assessment models, which are further soft-linked to two sectoral models, and explores the synergies and trade-offs among three approaches to living without Russian gas in Europe: (a) replacing with other gas imports, (b) boosting domestic energy production, and (c) reducing demand and accelerating energy efficiency. We find that substituting Russian gas from other trade partners would miss an opportunity to accelerate decarbonisation in end-use sectors while risking further fossil-fuel lock-ins, despite featuring the lowest gas price spikes and potentially reducing heating costs for end-users in the near term. Boosting domestic, primarily renewable, energy production on the other hand would instead require considerable investments, potentially burdening consumers. Energy demand reductions, however, could offer considerable space for further emissions cuts at the lowest power-sector investment costs; nonetheless, an energy efficiency-driven strategy would also risk relocation of energy-intensive industries, an aspect of increasing relevance to EU policymakers.
- Published
- 2024
5. The computation of flow and heat transfer through stationary and orthogonally rotating u-bends
- Author
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Nikas, Konstantinos-Stephen P.
- Subjects
621.4022 - Published
- 2000
6. Theoretical modelling of the entrainment and thermomechanical effects of contamination particles in elastohydrodynamic contacts
- Author
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Nikas, Georgios
- Subjects
620.11223 ,Gears ,Bearings ,Abrasion ,Thermo-cracks - Published
- 1999
7. A multicriteria modeling approach for evaluating power generation scenarios under uncertainty : The case of green hydrogen in Greece
- Author
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Koutsandreas, Diamantis, Trachanas, Georgios P., Pappis, Ioannis, Nikas, Alexandros, Doukas, Haris, Psarras, John, Koutsandreas, Diamantis, Trachanas, Georgios P., Pappis, Ioannis, Nikas, Alexandros, Doukas, Haris, and Psarras, John
- Abstract
Clean energy technological innovations are widely acknowledged as a prerequisite to achieving ambitious long-term energy and climate targets. However, the optimal speed of their adoption has been parsimoniously studied in the literature. This study seeks to identify the optimal intensity of moving to a green hydrogen electricity sector in Greece, using the OSeMOSYS energy modeling framework. Green hydrogen policies are evaluated, first, on the basis of their robustness against uncertainty and, afterwards, against conflicting performance criteria and for different decision-making profiles towards risk, by applying the VIKOR and TOPSIS multi-criteria decision aid methods. Although our analysis focuses exclusively on the power sector and compares different rates of hydrogen penetration compared to a business-as-usual case without considering other game-changing innovations (such as other types of storage or carbon capture and storage), we find that a national transition to a green hydrogen economy can support Greece in potentially cutting at least 16 MtCO2 while stimulating investments of EUR 10–13 bn. over 2030–2050., QC 20231115
- Published
- 2023
- Full Text
- View/download PDF
8. Binding energies of ground and isomeric states in neutron-rich ruthenium isotopes: Measurements at JYFLTRAP and comparison to theory
- Author
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Hukkanen, M., Ryssens, Wouter, Ascher, P., Bender, M., Eronen, T., Grévy, Stéphane, Kankainen, Anu, Stryjczyk, M., Al Ayoubi, L., Ayet, S., Beliuskina, O., Delafosse, C., Ge, Z., Gerbaux, M., Gins, W., Husson, A., Jaries, A., Kujanpää, S., Mougeot, Romain, Nesterenko, D. A., Nikas, S., Penttilä, H., Pohjalainen, I., Raggio, A., Reponen, M., Rinta-Antila, S., de Roubin, A., Ruotsalainen, J., Virtanen, V., Weaver, A. P., Hukkanen, M., Ryssens, Wouter, Ascher, P., Bender, M., Eronen, T., Grévy, Stéphane, Kankainen, Anu, Stryjczyk, M., Al Ayoubi, L., Ayet, S., Beliuskina, O., Delafosse, C., Ge, Z., Gerbaux, M., Gins, W., Husson, A., Jaries, A., Kujanpää, S., Mougeot, Romain, Nesterenko, D. A., Nikas, S., Penttilä, H., Pohjalainen, I., Raggio, A., Reponen, M., Rinta-Antila, S., de Roubin, A., Ruotsalainen, J., Virtanen, V., and Weaver, A. P.
- Abstract
We report on precision mass measurements of Ru113,115,117 performed with the JYFLTRAP double Penning trap mass spectrometer at the Accelerator Laboratory of University of Jyväskylä. The phase-imaging ion-cyclotron-resonance technique was used to resolve the ground and isomeric states in Ru113,115 and enabled for the first time a measurement of the isomer excitation energies, Ex(Rum113)=100.5(8) keV and Ex(Rum115)=129(5) keV. The ground state of Ru117 was measured using the time-of-flight ion-cyclotron-resonance technique. The new mass-excess value for Ru117 is around 36 keV lower and seven times more precise than the previous literature value. With the more precise ground-state mass values, the evolution of the two-neutron separation energies is further constrained and a similar trend as predicted by the BSkG1 model is obtained up to the neutron number N=71., SCOPUS: ar.j, info:eu-repo/semantics/published
- Published
- 2023
9. A multimodel analysis of post-Glasgow climate targets and feasibility challenges
- Author
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van de Ven, D.-J., Mittal, S., Gambhir, A., Lamboll, R.D., Doukas, H., Giarola, S., Hawkes, A., Koasidis, K., Köberle, A.C., McJeon, H., Perdana, S., Peters, G.P., Rogelj, J., Sognnaes, I., Vielle, M., Nikas, A., van de Ven, D.-J., Mittal, S., Gambhir, A., Lamboll, R.D., Doukas, H., Giarola, S., Hawkes, A., Koasidis, K., Köberle, A.C., McJeon, H., Perdana, S., Peters, G.P., Rogelj, J., Sognnaes, I., Vielle, M., and Nikas, A.
- Abstract
The COP26 Glasgow process resulted in many countries strengthening their 2030 emissions reduction targets and announcing net-zero pledges for 2050–2070 but it is not clear how this would impact future warming. Here, we use four diverse integrated assessment models (IAMs) to assess CO2 emission trajectories in the near- and long-term on the basis of national policies and pledges, combined with a non-CO2 infilling model and a simple climate model to assess the temperature implications. We also consider the feasibility of national long-term pledges towards net-zero. While near-term pledges alone lead to warming above 2 °C, the addition of long-term pledges leads to emissions trajectories compatible with a future well below 2 °C, across all four IAMs. However, while IAM heterogeneity translates to diverse decarbonization pathways towards long-term targets, all modelled pathways indicate several feasibility concerns, relating to the cost of mitigation and the rates and scales of deployed technologies and measures.
- Published
- 2023
- Full Text
- View/download PDF
10. Vitamin-V: Virtual Environment and Tool-boxing for Trustworthy Development of RISC-V based Cloud Services
- Author
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Arelakis, A., Arnau, J. M., Berral, J. L., Call, A., Canal, R., Di Carlo, S., Costa, J., Gizopoulos, D., Karakostas, V., Lubrano, F., Nikas, K., Nikolakopoulos, Y., Otero, B., Papadimitriou, G., Papaefstathiou, I., Pnevmatikatos, D., Raho, D., Rigo, A., Rodríguez, E., Savino, A., Scionti, A., Tampouratzis, N., Torregrosa, A., Arelakis, A., Arnau, J. M., Berral, J. L., Call, A., Canal, R., Di Carlo, S., Costa, J., Gizopoulos, D., Karakostas, V., Lubrano, F., Nikas, K., Nikolakopoulos, Y., Otero, B., Papadimitriou, G., Papaefstathiou, I., Pnevmatikatos, D., Raho, D., Rigo, A., Rodríguez, E., Savino, A., Scionti, A., Tampouratzis, N., and Torregrosa, A.
- Abstract
Vitamin-V is a 2023-2025 Horizon Europe project that aims to develop a complete RISC-V open-source software stack for cloud services with comparable performance to the cloud-dominant x86 counterpart and a powerful virtual execution environment for software development, validation, verification, and test that considers the relevant RISC-V ISA extensions for cloud deployment., Comment: Paper accepted and presented at the RISC-V Summit Europe, Barcelona, 5-9th June 2023. arXiv admin note: substantial text overlap with arXiv:2305.01983
- Published
- 2023
11. A multimodel analysis of post-Glasgow climate targets and feasibility challenges
- Author
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van de Ven, D.J., Mittal, S., Gambhir, A., Lamboll, R.D., Doukas, H., Giarola, S., Hawkes, A., Koasidis, K., Köberle, A.C., McJeon, H., Perdana, S., Peters, G.P., Rogelj, J., Sognnaes, I., Vielle, M., Nikas, A., van de Ven, D.J., Mittal, S., Gambhir, A., Lamboll, R.D., Doukas, H., Giarola, S., Hawkes, A., Koasidis, K., Köberle, A.C., McJeon, H., Perdana, S., Peters, G.P., Rogelj, J., Sognnaes, I., Vielle, M., and Nikas, A.
- Abstract
The COP26 Glasgow process resulted in many countries strengthening their 2030 emissions reduction targets and announcing net-zero pledges for 2050–2070 but it is not clear how this would impact future warming. Here, we use four diverse integrated assessment models (IAMs) to assess CO2 emission trajectories in the near- and long-term on the basis of national policies and pledges, combined with a non-CO2 infilling model and a simple climate model to assess the temperature implications. We also consider the feasibility of national long-term pledges towards net-zero. While near-term pledges alone lead to warming above 2 °C, the addition of long-term pledges leads to emissions trajectories compatible with a future well below 2 °C, across all four IAMs. However, while IAM heterogeneity translates to diverse decarbonization pathways towards long-term targets, all modelled pathways indicate several feasibility concerns, relating to the cost of mitigation and the rates and scales of deployed technologies and measures. © 2023, The Author(s), under exclusive licence to Springer Nature Limited.
- Published
- 2023
12. A multi-model analysis of the EU's path to net zero
- Author
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Boitier, B., Nikas, A., Gambhir, A., Koasidis, K., Elia, A., Al-Dabbas, K., Alibaş, Ş., Campagnolo, L., Chiodi, A., Delpiazzo, E., Doukas, H., Fougeyrollas, A., Gargiulo, M., Le Mouël, P., Neuner, F., Perdana, S., van de Ven, D.J., Vielle, M., Zagamé, P., Mittal, S., Boitier, B., Nikas, A., Gambhir, A., Koasidis, K., Elia, A., Al-Dabbas, K., Alibaş, Ş., Campagnolo, L., Chiodi, A., Delpiazzo, E., Doukas, H., Fougeyrollas, A., Gargiulo, M., Le Mouël, P., Neuner, F., Perdana, S., van de Ven, D.J., Vielle, M., Zagamé, P., and Mittal, S.
- Abstract
The European Union (EU) recently ratcheted its climate ambition to net-zero emissions by 2050, with a milestone of 55% emissions cuts in 2030. This study carries out a model inter-comparison to assess the EU's path, from “Fit for 55” in 2030 to an intermediate milestone in 2040 and onto net zero in 2050, offering insights at sectoral and member-state levels. Our model results support the bloc's ambition for its Emissions Trading System and Effort Sharing Regulation sectors while pointing to the need for near-complete decarbonization of electricity by 2040, enabled by considerable deployment of renewables (45%–65% in 2030, to 60%–70% in 2040, and to 75%–90% in 2050 in electricity generation) and carbon capture and storage (0.5–2 GtCO2/year by 2050). We also highlight the trade-offs between supply-side and harder-to-abate sectors, assess the ambition of member states for net zero and timing of coal phaseout, and reflect on the economic implications of investment, technical, and policy needs. © 2023 The Author(s)
- Published
- 2023
13. The movements of labour from Greece to the E.C. countries in the period after the end of World War II : a macroeconomic approach to the causes and the effects of these movements
- Author
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Nikas, Christos
- Subjects
304.6 ,Demography & population studies - Published
- 1992
14. Coupling circularity performance and climate action: From disciplinary silos to transdisciplinary modelling science
- Author
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Nikas, A., Xexakis, G., Koasidis, K., Acosta-Fernández, J., Arto, D., Calzadilla, A., Domenech, T., Gambhir, A., Giljum, S., Gonzalez-Eguino, M., Herbst, A., Ivanova, O., van Sluisveld, M.A.E., Van De Ven, D.-J., Karamaneas, A., Doukas, H., Nikas, A., Xexakis, G., Koasidis, K., Acosta-Fernández, J., Arto, D., Calzadilla, A., Domenech, T., Gambhir, A., Giljum, S., Gonzalez-Eguino, M., Herbst, A., Ivanova, O., van Sluisveld, M.A.E., Van De Ven, D.-J., Karamaneas, A., and Doukas, H.
- Abstract
Technological breakthroughs and policy measures targeting energy efficiency and clean energy alone will not suffice to deliver Paris Agreement-compliant greenhouse gas emissions trajectories in the next decades. Strong cases have recently been made for acknowledging the decarbonisation potential lying in transforming linear economic models into closed-loop industrial ecosystems and in shifting lifestyle patterns towards this direction. This perspective highlights the research capacity needed to inform on the role and potential of the circular economy for climate change mitigation and to enhance the scientific capabilities to quantitatively explore their synergies and trade-offs. This begins with establishing conceptual and methodological bridges amongst the relevant and currently fragmented research communities, thereby allowing an interdisciplinary integration and assessment of circularity, decarbonisation, and sustainable development. Following similar calls for science in support of climate action, a transdisciplinary scientific agenda is needed to co-create the goals and scientific processes underpinning the transition pathways towards a circular, net-zero economy with representatives from policy, industry, and civil society. Here, it is argued that such integration of disciplines, methods, and communities can then lead to new and/or structurally enhanced quantitative systems models that better represent critical industrial value chains, consumption patterns, and mitigation technologies. This will be a crucial advancement towards assessing the material implications of, and the contribution of enhanced circularity performance to, mitigation pathways that are compatible with the temperature goals of the Paris Agreement and the transition to a circular economy. © 2021 The Authors
- Published
- 2022
15. Stress relief during annealing of railway wheel steel characterized by synchrotron X-ray micro-diffraction
- Author
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Zhang, Yubin, Jessop, Casey, Dimitrios, Nikas, Yu, Tianbo, Liu, Wenjun, Ahlstrom, Johan, Zhang, Yubin, Jessop, Casey, Dimitrios, Nikas, Yu, Tianbo, Liu, Wenjun, and Ahlstrom, Johan
- Abstract
Railway wheels in service experience rolling contact fatigue loading, but also need to resist frictional heating on braking, yielding temperatures up to 500 degrees C. The combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of this study is to investigate the effect of annealing on local microstructure and residual stresses in railway wheel pearlitic steel (medium carbon steels, similar to 0.55 wt.% C) using synchroton X-ray Laue micro-diffraction. It is found that the local residual stress releases to a large extent after annealing at 500 degrees C. The stress formation and relief mechanisms and their relationship to the local microstructure are discussed.
- Published
- 2022
- Full Text
- View/download PDF
16. Effect of annealing on microstructure in railway wheel steel
- Author
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Dimitrios, Nikas, Zhang, Yubin, Ahlstrom, Johan, Dimitrios, Nikas, Zhang, Yubin, and Ahlstrom, Johan
- Abstract
Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads occur together with the high contact stresses, which combined can affect the mechanical properties of the material. In this study, the effects of annealing on local microstructure and mechanical properties in pearlitic railway wheel steel were investigated using electron microscopy and micro-hardness. It is found that after annealing at 650 degrees C, the room temperature hardness reduces about 25%, accompanied by significant spheroidization of cementite in the pearlitic colonies, though the size and the orientation gradients of the pearlitic colonies have not changed much. The relationship between the microstructural changes and the mechanical properties are discussed.
- Published
- 2022
- Full Text
- View/download PDF
17. Towards a green recovery in the EU: Aligning further emissions reductions with short- and long-term energy-sector employment gains
- Author
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Koasidis, K., Nikas, A., Van de Ven, D.J., Xexakis, G., Forouli, A., Mittal, S., Gambhir, A., Koutsellis, T., Doukas, H., Koasidis, K., Nikas, A., Van de Ven, D.J., Xexakis, G., Forouli, A., Mittal, S., Gambhir, A., Koutsellis, T., and Doukas, H.
- Abstract
To tackle the negative socioeconomic implications of the COVID-19 pandemic, the European Union (EU) introduced the Recovery and Resilience Facility, a financial instrument to help Member States recover, on the basis that minimum 37% of the recovery funds flow towards the green transition. This study contributes to the emerging modelling literature on assessing COVID-19 vis-à-vis decarbonisation efforts, with a particular focus on employment, by optimally allocating the green part of the EU recovery stimulus in selected low-carbon technologies and quantifying the trade-offs between resulting emissions reductions and employment gains in the energy sector. We couple an integrated assessment model with a multi-objective linear-programming model and an uncertainty analysis framework aiming to identify robust portfolio mixes. We find that it is possible to allocate recovery packages to align mitigation goals with both short- and long-term energy-sector employment, although over-emphasising the longer-term sustainability of new energy-sector jobs may be costlier and more vulnerable to uncertainties compared to prioritising environmental and near-term employment gains. Robust portfolios with balanced performance across objectives consistently feature small shares of offshore wind and nuclear investments, while the largest chunks are dominated by onshore wind and biofuels, two technologies with opposite impacts on near- and long-term employment gains. © 2022 The Authors
- Published
- 2022
18. Climate and sustainability co-governance in Kenya: A multi-criteria analysis of stakeholders' perceptions and consensus
- Author
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Koasidis, K., Nikas, A., Karamaneas, A., Saulo, M., Tsipouridis, I., Campagnolo, L., Gambhir, A., Van de Ven, D.J., McWilliams, B., Doukas, H., Koasidis, K., Nikas, A., Karamaneas, A., Saulo, M., Tsipouridis, I., Campagnolo, L., Gambhir, A., Van de Ven, D.J., McWilliams, B., and Doukas, H.
- Abstract
The Paris Agreement and the 2030 Agenda for Sustainable Development embody highly intertwined targets to act for climate in conjunction with sustainable development. This, however, entails different meanings and challenges across the world. Kenya, in particular, needs to address serious sustainability threats, like poverty and lack of modern and affordable energy access. This study uses a multi-criteria group decision aid and consensus measuring framework, to integrate both agendas, and engages with Kenyan stakeholders to help inform future mitigation research and policy in the country. Results showed that stakeholders highlight topics largely underrepresented in model-based mitigation analysis, such as biodiversity preservation and demand-side transformations, while pointing to gaps in cross-sectoral policies in relation to access to modern energy, agriculture, life on land, and climate change mitigation. With numerous past and recent policies aiming at these issues, persistent stakeholder concerns over these topics hint at limited success. Sectoral and technological priorities only recently emphasised in Kenyan policy efforts are also correlated with stakeholders' concerns, highlighting that progress is not only a matter of legislation, but also of coordination, consistency of targets, and comprehensibility. Higher bias is found among the preferences of stakeholders coming from the country's private sector. Results from this exercise can inform national policymakers on effectively reshaping the future direction of the country, as well as modelling efforts aimed at underpinning Kenya's energy, climate and sustainable development policy. © 2022 The Authors
- Published
- 2022
19. Effect of annealing on microstructure in railway wheel steel
- Author
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Nikas, Dimitrios, Zhang, Yubin, Ahlström, Johan, Nikas, Dimitrios, Zhang, Yubin, and Ahlström, Johan
- Abstract
Railway wheels are commonly made from medium carbon steels (~0.55 wt.% C), heat treated to a near pearlitic microstructure with 5–10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads occur together with the high contact stresses, which combined can affect the mechanical properties of the material. In this study, the effects of annealing on local microstructure and mechanical properties in pearlitic railway wheel steel were investigated using electron microscopy and micro-hardness. It is found that after annealing at 650 °C, the room temperature hardness reduces about 25%, accompanied by significant spheroidization of cementite in the pearlitic colonies, though the size and the orientation gradients of the pearlitic colonies have not changed much. The relationship between the microstructural changes and the mechanical properties are discussed.
- Published
- 2022
20. Coupling circularity performance and climate action : from disciplinary silos to transdisciplinary modelling science
- Author
-
Nikas, Alexandros, Xexakis, Georgios, Koasidis, Konstantinos, Acosta-Fernández, José, Arto, Inaki, Calzadilla, Alvaro, Domenech, Teresa, Gambhir, Ajay, Giljum, Stefan, Gonzalez-Eguinod, Mike, Herbst, Andrea, Ivanova, Olga, van Sluisveld, Mariesse A. E., Van De Ven, Dirk-Jan, Karamaneas, Anastasios, Doukas, Haris, Nikas, Alexandros, Xexakis, Georgios, Koasidis, Konstantinos, Acosta-Fernández, José, Arto, Inaki, Calzadilla, Alvaro, Domenech, Teresa, Gambhir, Ajay, Giljum, Stefan, Gonzalez-Eguinod, Mike, Herbst, Andrea, Ivanova, Olga, van Sluisveld, Mariesse A. E., Van De Ven, Dirk-Jan, Karamaneas, Anastasios, and Doukas, Haris
- Abstract
Technological breakthroughs and policy measures targeting energy efficiency and clean energy alone will not suffice to deliver Paris Agreement-compliant greenhouse gas emissions trajectories in the next decades. Strong cases have recently been made for acknowledging the decarbonisation potential lying in transforming linear economic models into closed-loop industrial ecosystems and in shifting lifestyle patterns towards this direction. This perspective highlights the research capacity needed to inform on the role and potential of the circular economy for climate change mitigation and to enhance the scientific capabilities to quantitatively explore their synergies and trade-offs. This begins with establishing conceptual and methodological bridges amongst the relevant and currently fragmented research communities, thereby allowing an interdisciplinary integration and assessment of circularity, decarbonisation, and sustainable development. Following similar calls for science in support of climate action, a transdisciplinary scientific agenda is needed to co-create the goals and scientific processes underpinning the transition pathways towards a circular, net-zero economy with representatives from policy, industry, and civil society. Here, it is argued that such integration of disciplines, methods, and communities can then lead to new and/or structurally enhanced quantitative systems models that better represent critical industrial value chains, consumption patterns, and mitigation technologies. This will be a crucial advancement towards assessing the material implications of, and the contribution of enhanced circularity performance to, mitigation pathways that are compatible with the temperature goals of the Paris Agreement and the transition to a circular economy.
- Published
- 2022
21. Perspective of comprehensive and comprehensible multi-model energy and climate science in Europe
- Author
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Nikas, Alexandros and Nikas, Alexandros
- Abstract
Producción Científica, Europe’s capacity to explore the envisaged pathways that achieve its near- and long-term energy and climate objectives needs to be significantly enhanced. In this perspective, we discuss how this capacity is supported by energy and climate-economy models, and how international modelling teams are organised within structured communication channels and consortia as well as coordinate multi-model analyses to provide robust scientific evidence. Noting the lack of such a dedicated channel for the highly active yet currently fragmented European modelling landscape, we highlight the importance of transparency of modelling capabilities and processes, harmonisation of modelling parameters, disclosure of input and output datasets, interlinkages among models of different geographic granularity, and employment of models that transcend the highly harmonised core of tools used in model inter-comparisons. Finally, drawing from the COVID-19 pandemic, we discuss the need to expand the modelling comfort zone, by exploring extreme scenarios, disruptive innovations, and questions that transcend the energy and climate goals across the sustainability spectrum. A comprehensive and comprehensible multi-model framework offers a real example of “collective” science diplomacy, as an instrument to further support the ambitious goals of the EU Green Deal, in compliance with the EU claim to responsible research., H2020 European Commission Projects “PARIS REINFORCE” under Grant Agreement No. 820846, “LOCOMOTION” under Grant Agreement No. 821105, “SENTINEL” under Grant Agreement No. 837089, and “NAVIGATE” under Grant Agreement No. 821124.
- Published
- 2021
22. A multi-model analysis of long-term emissions and warming implications of current mitigation efforts
- Author
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Sognnaes, I., Gambhir, A., van de Ven, D.-J., Nikas, A., Anger-Kraavi, A., Bui, H., Campagnolo, L., Delpiazzo, E., Doukas, H., Giarola, S., Grant, N., Hawkes, A., Köberle, A.C., Kolpakov, A., Mittal, S., Moreno, J., Perdana, S., Rogelj, J., Vielle, M., Peters, G.P., Sognnaes, I., Gambhir, A., van de Ven, D.-J., Nikas, A., Anger-Kraavi, A., Bui, H., Campagnolo, L., Delpiazzo, E., Doukas, H., Giarola, S., Grant, N., Hawkes, A., Köberle, A.C., Kolpakov, A., Mittal, S., Moreno, J., Perdana, S., Rogelj, J., Vielle, M., and Peters, G.P.
- Abstract
Most of the integrated assessment modelling literature focuses on cost-effective pathways towards given temperature goals. Conversely, using seven diverse integrated assessment models, we project global energy CO2 emissions trajectories on the basis of near-term mitigation efforts and two assumptions on how these efforts continue post-2030. Despite finding a wide range of emissions by 2050, nearly all the scenarios have median warming of less than 3 °C in 2100. However, the most optimistic scenario is still insufficient to limit global warming to 2 °C. We furthermore highlight key modelling choices inherent to projecting where emissions are headed. First, emissions are more sensitive to the choice of integrated assessment model than to the assumed mitigation effort, highlighting the importance of heterogeneous model intercomparisons. Differences across models reflect diversity in baseline assumptions and impacts of near-term mitigation efforts. Second, the common practice of using economy-wide carbon prices to represent policy exaggerates carbon capture and storage use compared with explicitly modelling policies.
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- 2021
23. Perspective of comprehensive and comprehensible multi-model energy and climate science in Europe
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Nikas, A., Gambhir, A., Trutnevyte, E., Koasidis, K., Lund, H., Thellufsen, J.Z., Mayer, D., Zachmann, G., Miguel, L.J., Ferreras-Alonso, N., Sognnaes, I., Peters, G.P., Colombo, E., Howells, M., Hawkes, A., van den Broek, M., Van de Ven, D.J., Gonzalez-Eguino, M., Flamos, A., Doukas, H., Nikas, A., Gambhir, A., Trutnevyte, E., Koasidis, K., Lund, H., Thellufsen, J.Z., Mayer, D., Zachmann, G., Miguel, L.J., Ferreras-Alonso, N., Sognnaes, I., Peters, G.P., Colombo, E., Howells, M., Hawkes, A., van den Broek, M., Van de Ven, D.J., Gonzalez-Eguino, M., Flamos, A., and Doukas, H.
- Abstract
Europe’s capacity to explore the envisaged pathways that achieve its near- and long-term energy and climate objectives needs to be significantly enhanced. In this perspective, we discuss how this capacity is supported by energy and climate-economy models, and how international modelling teams are organised within structured communication channels and consortia as well as coordinate multi-model analyses to provide robust scientific evidence. Noting the lack of such a dedicated channel for the highly active yet currently fragmented European modelling landscape, we highlight the importance of transparency of modelling capabilities and processes, harmonisation of modelling parameters, disclosure of input and output datasets, interlinkages among models of different geographic granularity, and employment of models that transcend the highly harmonised core of tools used in model inter-comparisons. Finally, drawing from the COVID-19 pandemic, we discuss the need to expand the modelling comfort zone, by exploring extreme scenarios, disruptive innovations, and questions that transcend the energy and climate goals across the sustainability spectrum. A comprehensive and comprehensible multi-model framework offers a real example of “collective” science diplomacy, as an instrument to further support the ambitious goals of the EU Green Deal, in compliance with the EU claim to responsible research.
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- 2021
24. Challenges in the harmonisation of global integrated assessment models: A comprehensive methodology to reduce model response heterogeneity
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Giarola, S., Mittal, S., Vielle, M., Perdana, S., Campagnolo, L., Delpiazzo, E., Bui, H., Kraavi, A.A., Kolpakov, A., Sognnaes, I., Peters, G., Hawkes, A., Köberle, A.C., Grant, N., Gambhir, A., Nikas, A., Doukas, H., Moreno, J., van de Ven, D.-J., Giarola, S., Mittal, S., Vielle, M., Perdana, S., Campagnolo, L., Delpiazzo, E., Bui, H., Kraavi, A.A., Kolpakov, A., Sognnaes, I., Peters, G., Hawkes, A., Köberle, A.C., Grant, N., Gambhir, A., Nikas, A., Doukas, H., Moreno, J., and van de Ven, D.-J.
- Abstract
Harmonisation sets the ground to a solid inter-comparison of integrated assessment models. A clear and transparent harmonisation process promotes a consistent interpretation of the modelling outcomes divergences and, reducing the model variance, is instrumental to the use of integrated assessment models to support policy decision-making. Despite its crucial role for climate economic policies, the definition of a comprehensive harmonisation methodology for integrated assessment modelling remains an open challenge for the scientific community. This paper proposes a framework for a harmonisation methodology with the definition of indispensable steps and recommendations to overcome stumbling blocks in order to reduce the variance of the outcomes which depends on controllable modelling assumptions. The harmonisation approach of the PARIS REINFORCE project is presented here to layout such a framework. A decomposition analysis of the harmonisation process is shown through 6 integrated assessment models (GCAM, ICES-XPS, MUSE, E3ME, GEMINI-E3, and TIAM). Results prove the potentials of the proposed framework to reduce the model variance and present a powerful diagnostic tool to feedback on the quality of the harmonisation itself. © 2021
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- 2021
25. Modelling of temperature and strain rate dependent behaviour of pearlitic steel in block braked railway wheels
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Esmaeili, Ali, Ahlstrom, Johan, Ekh, Magnus, Dimitrios, Nikas, Vernersson, Tore, Esmaeili, Ali, Ahlstrom, Johan, Ekh, Magnus, Dimitrios, Nikas, and Vernersson, Tore
- Abstract
Block braked railway wheels are subjected to thermal and rolling contact loading. The thermal loading results in high temperatures and thermal stresses which cause slow time dependent processes such as creep, relaxation and static recovery of the wheel material. At the same time, the rolling contact loading implies a very fast mechanical load application. This paper is focused on material modeling of pearlitic steel for a wide range of loading rates at elevated temperatures. The starting point is a viscoplasticity model including nonlinear isotropic and kinematic hardening. The Delobelle overstress function is employed to capture strain rate dependent response of the material. The model also includes static recovery of the hardening to capture slower viscous (diffusion dominated) behaviour of the material. Experiments for the pearlitic wheel steel ER7 in terms of cyclic strain-controlled uniaxial tests with hold-time, uniaxial ratchetting tests including rapid cycles and biaxial cyclic tests with tension/compression and torsion are used to calibrate the material model. These experiments were performed under isothermal conditions at different temperatures. In the ratchetting tests, higher loading rates are obtained and these have been used to calibrate the high strain rate response of the viscoplasticity model. The paper is concluded with a numerical example of a block braked wheel where the importance of accounting for the viscoplasticity in modelling is highlighted.
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- 2021
- Full Text
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26. The Albanian Migration to Greece and the Refugee Crisis of 2015 from the Greek Perspective
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Aspasios, Dimitrios, Nikas, Christos, Aspasios, Dimitrios, and Nikas, Christos
- Abstract
Although migration has always been a timeless and volatile phenomenon, modern transnational movements of people have become a dominant topic of interest by constantly acquiring new characteristics that modify their evolutionary process. Europe is a geographical area that has been significantly affected by recent changes as a result of the evolution of migration flows of the last 30 years. The urgent need to initially understand and later implement evidence-based policies in order to sufficiently manage the migration phenomenon can be considered as the basic spark that led to the scientific blast of the 21st century, focusing on the gradual development of migration studies. One of the most notable efforts of the scientific community was the use of the comparison method to examine, understand, and in some cases even forecast the characteristics of specific migration case studies, thereby forming the backbone of comparative migration research in general. Greece, due to its geographical position, has been unintentionally positioned, many times, inside the so called "ring of fire", as result of multiple factors and disastrous events that evolved mainly in its neighbouring countries, forcing massive, irregular migration flows to its external borders. The outbreak of the Albanian exodus in the early 1990s and the recent refugee flows of 2015 can be described as two major migration crises that have occurred in Greek’s contemporary history, making their comparison a fruitful example of the potential capabilities of the above-mentioned method, contributing to a holistic study of the migration phenomenon in Greece.
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- 2021
27. Exploiting page table locality for Agile TLB Prefetching
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Universitat Politècnica de Catalunya. Doctorat en Arquitectura de Computadors, Barcelona Supercomputing Center, Vavouliotis, Georgios, Alvarez Martí, Lluc, Karakostas, Vasileios, Nikas, Konstantinos, Koziris, Nectarios, Jiménez, Daniel A., Casas, Marc, Universitat Politècnica de Catalunya. Doctorat en Arquitectura de Computadors, Barcelona Supercomputing Center, Vavouliotis, Georgios, Alvarez Martí, Lluc, Karakostas, Vasileios, Nikas, Konstantinos, Koziris, Nectarios, Jiménez, Daniel A., and Casas, Marc
- Abstract
Frequent Translation Lookaside Buffer (TLB) misses incur high performance and energy costs due to page walks required for fetching the corresponding address translations. Prefetching page table entries (PTEs) ahead of demand TLB accesses can mitigate the address translation performance bottleneck, but each prefetch requires traversing the page table, triggering additional accesses to the memory hierarchy. Therefore, TLB prefetching is a costly technique that may undermine performance when the prefetches are not accurate.In this paper we exploit the locality in the last level of the page table to reduce the cost and enhance the effectiveness of TLB prefetching by fetching cache-line adjacent PTEs "for free". We propose Sampling-Based Free TLB Prefetching (SBFP), a dynamic scheme that predicts the usefulness of these "free" PTEs and prefetches only the ones most likely to prevent TLB misses. We demonstrate that combining SBFP with novel and state-of-the-art TLB prefetchers significantly improves miss coverage and reduces most memory accesses due to page walks.Moreover, we propose Agile TLB Prefetcher (ATP), a novel composite TLB prefetcher particularly designed to maximize the benefits of SBFP. ATP efficiently combines three low-cost TLB prefetchers and disables TLB prefetching for those execution phases that do not benefit from it. Unlike state-of-the-art TLB prefetchers that correlate patterns with only one feature (e.g., strides, PC, distances), ATP correlates patterns with multiple features and dynamically enables the most appropriate TLB prefetcher per TLB miss.To alleviate the address translation performance bottleneck, we propose a unified solution that combines ATP and SBFP. Across an extensive set of industrial workloads provided by Qualcomm, ATP coupled with SBFP improves geometric speedup by 16.2%, and eliminates on average 37% of the memory references due to page walks. Considering the SPEC CPU 2006 and SPEC CPU 2017 benchmark suites, ATP with SBFP increas, This work is partially supported by the Spanish Ministry of Science and Technology through the PID2019- 107255GB project, the Generalitat de Catalunya (contract 2017-SGR-1414), the NSF grants CCF-1912617 and CNS1938064, and generous gifts from Intel Labs. Georgios Vavouliotis has been supported by the Spanish Ministry of Economy, Industry and Competitiveness and the European Social Fund under the FPI fellowship No. PRE2018-087046. Lluc Alvarez has been supported by the Spanish Ministry of Economy, Industry and Competitiveness under the Juan de la Cierva Formacion fellowship No. FJCI-2016-30984. Marc Casas has been supported by the Spanish Ministry of Economy, Industry and Competitiveness under the Ramon y Cajal fellowship No. RYC-2017-23269., Peer Reviewed, Postprint (author's final draft)
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- 2021
28. Where is the EU headed given its current climate policy? A stakeholder-driven model inter-comparison
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Nikas, A., Elia, A., Boitier, B., Koasidis, K., Doukas, H., Cassetti, G., Anger-Kraavi, A., Campagnolo, L., Bui, H., De Miglio, R., Delpiazzo, E., Fougeyrollas, A., Gambhir, A., Gargiulo, M., Giarola, S., Grant, N., Hawkes, A., Herbst, A., Köberle, A. C., Kolpakov, A., Le Mouël, P., McWilliams, B., Mittal, S., Neuner, F., Moreno, J., Perdana, S., Plötz, P., Peters, G. P., Rogelj, J., Sognnæs, I., Van de Ven, D. J., Vielle, M., Zachmann, G., Zagamé, P., Chiodi, A., Nikas, A., Elia, A., Boitier, B., Koasidis, K., Doukas, H., Cassetti, G., Anger-Kraavi, A., Campagnolo, L., Bui, H., De Miglio, R., Delpiazzo, E., Fougeyrollas, A., Gambhir, A., Gargiulo, M., Giarola, S., Grant, N., Hawkes, A., Herbst, A., Köberle, A. C., Kolpakov, A., Le Mouël, P., McWilliams, B., Mittal, S., Neuner, F., Moreno, J., Perdana, S., Plötz, P., Peters, G. P., Rogelj, J., Sognnæs, I., Van de Ven, D. J., Vielle, M., Zachmann, G., Zagamé, P., and Chiodi, A.
- Abstract
Recent calls to do climate policy research with, rather than for, stakeholders have been answered in non-modelling science. Notwithstanding progress in modelling literature, however, very little of the scenario space traces back to what stakeholders are ultimately concerned about. With a suite of eleven integrated assessment, energy system and sectoral models, we carry out a model inter-comparison for the EU, the scenario logic and research questions of which have been formulated based on stakeholders' concerns. The output of this process is a scenario framework exploring where the region is headed rather than how to achieve its goals, extrapolating its current policy efforts into the future. We find that Europe is currently on track to overperforming its pre-2020 40% target yet far from its newest ambition of 55% emissions cuts by 2030, as well as looking at a 1.0 2.35 GtCO2 emissions range in 2050. Aside from the importance of transport electrification, deployment levels of carbon capture and storage are found intertwined with deeper emissions cuts and with hydrogen diffusion, with most hydrogen produced post-2040 being blue. Finally, the multi-model exercise has highlighted benefits from deeper decarbonisation in terms of energy security and jobs, and moderate to high renewables-dominated investment needs. © 2021 The Authors
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- 2021
29. A Review of the Pharmacological Characteristics of Vanillic Acid
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Ingole, Ashwini, Kadam, Megha P, Dalu, Aishwarya P., Kute, Shital M, Mange, Piyusha R, Theng, Vaishali D, Lahane, Om R, Nikas, Aniket P, Kawal, Yash V, Nagrik, Shatrughna U., Patil, Prashant A., Ingole, Ashwini, Kadam, Megha P, Dalu, Aishwarya P., Kute, Shital M, Mange, Piyusha R, Theng, Vaishali D, Lahane, Om R, Nikas, Aniket P, Kawal, Yash V, Nagrik, Shatrughna U., and Patil, Prashant A.
- Abstract
A dihydroxybenzoic acid analog used as a flavoring agent is vanillic acid (4hydroxy-3-methoxybenzoic acid). It's a form of vanillin that has been oxidized. It's also a step in the process of making vanillin from Ferulic Acid. Vanillic acid has seen a lot of press because of its many uses in the cosmetics, fruit, flavorings, cigarettes,alcohols, drinks, and polymer sectors. It's said to have effective antioxidant, anti-inflammatory, and neuroprotective properties. The pharmacological impact on oxidative stress-induced neuro-degeneration, on the other hand, have not been thoroughly examined. The pharmacological properties of vanillic Acid lead to its possible use in the treatment of various diseases. Keywords: Vanillic acid, Pharmacological Potential, wound healing, Antioxidants
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- 2021
30. Herpes simplex virus ribonucleotide reductase : structural features and transcriptional regulation
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Nikas, Ioannis
- Subjects
579.2 - Abstract
Ribonucleotide reductase (EC 1.17.4.1. ) catalyses the direct reduction of all four ribonucleotides to the corresponding deoxyribonucleotides, this reaction being the first unique step in the de novo pathway of DNA biosynthesis. The herpes simplex virus type 1 (HSV-1)-induced enzyme is composed of two non-identical subunits, termed large (RR1) and small (RR2), which are dimers of the Vmw136 (RR1) and Vmw38 (RR2) polypeptides respectively. These polypeptides are specified by two early, unspliced and 3' co-terminal mRNAs with sizes of 5.0kb (RR1 mRNA) and 1.2kb (RR2 mRNA). The work presented in this thesis has been primarily directed at obtaining the predicted amino acid sequence of the HSV-1 RR1 polypeptide. The HSV-1 RR1 and RR2 amino acid sequences were analysed for conserved structural and functional features by comparisons to equivalent polypeptides of herpesviral and cellular origin. Other studies have identified the nucleotide changes in a portion of the RR1 gene of the HSV-1 temperature-sensitive (ts) mutant tsl207 and have examined the transcriptional regulation of RR1 and RR2 mRNA expression. The Nucleotide and Predicted Amino Acid Sequence of the HSV-1 RR1 Polypeptide. The nucleotide sequence of the HSV-1 DNA region encoding the RR1 polypeptide was obtained with the M13 dideoxy/chain termination method in combination with a 'shotgun' cloning approach. The sequencing data predicted that the RR1 DNA coding region is an open reading frame (ORF) of 3414 nucleotides which encodes a polypeptide of 1137 amino acids in length. In contrast to the remainder of the RR1 polypeptide, the N-terminal region contains unique amino acid composition features and seven sets of tandemly repeated amino acid sequences. A hypothetical scheme of evolutionary events leading to the formation of this region has been postulated. Further, as this region appears not be directly involved in enzymatic activity, a possible function has been suggested on the basis of two potential nuclear localisation signals. Amino Acid Conservation between Herpesvirus and Cellular Ribonucleotide Reductases. Analysis of amino acid conservation between the HSV-1 RR1 and RR2 polypeptides with identified or proposed large (RR L) and small (RRS) subunit polypeptides of herpesviral or cellular origin was performed using computer programs. a) Comparisons of the HSV-1 RR1 polypeptide with homologue RRL polypeptides. Comparison of the HSV-1 RR1 polypeptide with the equivalent herpes simplex virus type 2 (HSV-2) polypeptide revealed that they are essentially colinear with the exception of the N-terminal regions where number of insertions or deletions were predicted. Other analyses revealed that the RR1 N-terminal region was absent from other RRL polypeptides while the colinear parts exhibited clustered homology. b) Comparisons of the HSV-1 RR2 polypeptide with homologue herpesviral RRS polypeptides. Comparisons of the HSV-1 RR2 polypeptide with homologue herpesviral RRS polypeptides revealed the existence of clustered homology. The Escherichia coli (E. coli) tyrosine residue, on which the (essential for function) stable free radical has been localised, is conserved in all the RRS polypeptides examined These comparisons strongly indicate that the herpesviral RRL and RRS polypeptides examined are the constituents of the ribonucleotide reductase activities specified by these viruses. Conserved Structural and Potential Functional Features of the Herpesviral and Cellular Ribonucleotide Reductases. To identify more precisely regions of clustered homology and to determine potential functional features of the RRL and RRS polypeptide sequences, these were aligned with the consensus template alignment program and secondary structure predictions were obtained.
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- 1988
31. An integrative multi-omics analysis to identify candidate DNA methylation biomarkers related to prostate cancer risk.
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Wu, Lang, Yang, Yaohua, Guo, Xingyi, Shu, Xiao-Ou, Cai, Qiuyin, Shu, Xiang, Li, Bingshan, Tao, Ran, Wu, Chong, Nikas, Jason B, Sun, Yanfa, Zhu, Jingjing, Roobol, Monique J, Giles, Graham G, Brenner, Hermann, John, Esther M, Clements, Judith, Grindedal, Eli Marie, Park, Jong Y, Stanford, Janet L, Kote-Jarai, Zsofia, Haiman, Christopher A, Eeles, Rosalind A, Zheng, Wei, Long, Jirong, Wu, Lang, Yang, Yaohua, Guo, Xingyi, Shu, Xiao-Ou, Cai, Qiuyin, Shu, Xiang, Li, Bingshan, Tao, Ran, Wu, Chong, Nikas, Jason B, Sun, Yanfa, Zhu, Jingjing, Roobol, Monique J, Giles, Graham G, Brenner, Hermann, John, Esther M, Clements, Judith, Grindedal, Eli Marie, Park, Jong Y, Stanford, Janet L, Kote-Jarai, Zsofia, Haiman, Christopher A, Eeles, Rosalind A, Zheng, Wei, and Long, Jirong
- Abstract
It remains elusive whether some of the associations identified in genome-wide association studies of prostate cancer (PrCa) may be due to regulatory effects of genetic variants on CpG sites, which may further influence expression of PrCa target genes. To search for CpG sites associated with PrCa risk, here we establish genetic models to predict methylation (N = 1,595) and conduct association analyses with PrCa risk (79,194 cases and 61,112 controls). We identify 759 CpG sites showing an association, including 15 located at novel loci. Among those 759 CpG sites, methylation of 42 is associated with expression of 28 adjacent genes. Among 22 genes, 18 show an association with PrCa risk. Overall, 25 CpG sites show consistent association directions for the methylation-gene expression-PrCa pathway. We identify DNA methylation biomarkers associated with PrCa, and our findings suggest that specific CpG sites may influence PrCa via regulating expression of candidate PrCa target genes., Alicja Wolk (alwol516) is a collaborator, Orthopaedics, Department of Surgical Sciences, Uppsala Universitet
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- 2020
- Full Text
- View/download PDF
32. A multiple-uncertainty analysis framework for integrated assessment modelling of several sustainable development goals
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Forouli, Aikaterini, Nikas, A., Van de Ven, Dirk-Jan Petrus Adrianus, Sampedro, J., Doukas, H., Forouli, Aikaterini, Nikas, A., Van de Ven, Dirk-Jan Petrus Adrianus, Sampedro, J., and Doukas, H.
- Abstract
This research introduces a two-level integration of climate-economy modelling and portfolio analysis, to simulate technological subsidisation with implications for multiple Sustainable Development Goals (SDGs), across socioeconomic trajectories and considering different levels of uncertainties. We use integrated assessment modelling outputs relevant for progress across three SDGs namely air pollution-related mortality (SDG3), access to clean energy (SDG7) and greenhouse gas emissions (SDG13) calculated with the Global Change Assessment Model (GCAM) for different subsidy levels for six sustainable technologies, across three Shared Socioeconomic Pathways (SSPs), feeding them into a portfolio analysis model. Optimal portfolios that are robust in the individual socioeconomic scenarios as well as across the socioeconomic scenarios are identified, by means of an SSP-robustness score. A second link between the two models is established, by feeding portfolio analysis results back into GCAM. Application in a case study for Eastern Africa confirms that most SSP-robust portfolios show smaller output ranges among scenarios.
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- 2020
33. The importance of stakeholders in scoping risk assessments—Lessons from low-carbon transitions
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van Vliet, Oscar (author), Hanger-Kopp, Susanne (author), Nikas, Alexandros (author), Spijker, Eise (author), Carlsen, Henrik (author), Doukas, Haris (author), Della Santina, C. (author), van Vliet, Oscar (author), Hanger-Kopp, Susanne (author), Nikas, Alexandros (author), Spijker, Eise (author), Carlsen, Henrik (author), Doukas, Haris (author), and Della Santina, C. (author)
- Abstract
Identifying the risks that could impact a low-carbon transition is a prerequisite to assessing and managing these risks. We systematically characterise risks associated with decarbonisation pathways in fifteen case studies conducted in twelve countries around the world. We find that stakeholders from business, government, NGOs, and others supplied some 40 % of these risk inputs, significantly widening the scope of risks considered by academics and experts. Overall, experts and academics consider more economic risks and assess these with quantitative methods and models, while other stakeholders consider political risks more. To avoid losing sight of risks that cannot be easily quantified and modelled, including some economic risks, impact assessment modelling should be complemented with qualitative research and active stakeholder engagement. A systematic risk elicitation facilitates communication with stakeholders, enables better risk mitigation, and increases the chance of a sustainable transition., Learning & Autonomous Control
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- 2020
- Full Text
- View/download PDF
34. The desirability of transitions in demand: Incorporating behavioural and societal transformations into energy modelling
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Nikas, Alexandros (author), Lieu, J. (author), Sorman, Alevgul (author), Gambhir, Ajay (author), Turhan, Ethemcan (author), Baptista, Bianca Vienni (author), Doukas, Haris (author), Nikas, Alexandros (author), Lieu, J. (author), Sorman, Alevgul (author), Gambhir, Ajay (author), Turhan, Ethemcan (author), Baptista, Bianca Vienni (author), and Doukas, Haris (author)
- Abstract
Quantitative systems modelling in support of climate policy has tended to focus more on the supply side in assessing interactions among technology, economy, environment, policy and society. By contrast, the demand side is usually underrepresented, often emphasising technological options for energy efficiency improvements. In this perspective, we argue that scientific support to climate action is not only about exploring capacity of “what”, in terms of policy and outcome, but also about assessing feasibility and desirability, in terms of “when”, “where” and especially for “whom”. Without the necessary behavioural and societal transformations, the world faces an inadequate response to the climate crisis challenge. This could result from poor uptake of low-carbon technologies, continued high-carbon intensive lifestyles, or economy-wide rebound effects. For this reason, we propose a framing for a holistic and transdisciplinary perspective on the role of human choices and behaviours in influencing the low-carbon transition, starting from the desires of individuals and communities, and analysing how these interact with the energy and economic landscape, leading to systemic change at the macro-level. In making a case for a political ecology agenda, we expand our scope, from comprehending the role of societal acceptance and uptake of end-use technologies, to co-developing knowledge with citizens from non-mainstream and marginalised communities, and to defining the modelling requirements to assess the decarbonisation potential of shifting lifestyle patterns in climate change and action., Organisation and Governance
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- 2020
- Full Text
- View/download PDF
35. An integrative multi-omics analysis to identify candidate DNA methylation biomarkers related to prostate cancer risk
- Author
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Wu, L, Yang, Y, Guo, X, Shu, X-O, Cai, Q, Shu, X, Li, B, Tao, R, Wu, C, Nikas, JB, Sun, Y, Zhu, J, Roobol, MJ, Giles, GG, Brenner, H, John, EM, Clements, J, Grindedal, EM, Park, JY, Stanford, JL, Kote-Jarai, Z, Haiman, CA, Eeles, RA, Zheng, W, Wu, L, Yang, Y, Guo, X, Shu, X-O, Cai, Q, Shu, X, Li, B, Tao, R, Wu, C, Nikas, JB, Sun, Y, Zhu, J, Roobol, MJ, Giles, GG, Brenner, H, John, EM, Clements, J, Grindedal, EM, Park, JY, Stanford, JL, Kote-Jarai, Z, Haiman, CA, Eeles, RA, and Zheng, W
- Abstract
It remains elusive whether some of the associations identified in genome-wide association studies of prostate cancer (PrCa) may be due to regulatory effects of genetic variants on CpG sites, which may further influence expression of PrCa target genes. To search for CpG sites associated with PrCa risk, here we establish genetic models to predict methylation (N = 1,595) and conduct association analyses with PrCa risk (79,194 cases and 61,112 controls). We identify 759 CpG sites showing an association, including 15 located at novel loci. Among those 759 CpG sites, methylation of 42 is associated with expression of 28 adjacent genes. Among 22 genes, 18 show an association with PrCa risk. Overall, 25 CpG sites show consistent association directions for the methylation-gene expression-PrCa pathway. We identify DNA methylation biomarkers associated with PrCa, and our findings suggest that specific CpG sites may influence PrCa via regulating expression of candidate PrCa target genes.
- Published
- 2020
36. The importance of stakeholders in scoping risk assessments—Lessons from low-carbon transitions
- Author
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van Vliet, O., Hanger-Kopp, S., Nikas, A., Spijker, E., Carlsen, H., Doukas, H., Lieu, J., van Vliet, O., Hanger-Kopp, S., Nikas, A., Spijker, E., Carlsen, H., Doukas, H., and Lieu, J.
- Abstract
Identifying the risks that could impact a low-carbon transition is a prerequisite to assessing and managing these risks. We systematically characterise risks associated with decarbonisation pathways in fifteen case studies conducted in twelve countries around the world. We find that stakeholders from business, government, NGOs, and others supplied some 40 % of these risk inputs, significantly widening the scope of risks considered by academics and experts. Overall, experts and academics consider more economic risks and assess these with quantitative methods and models, while other stakeholders consider political risks more. To avoid losing sight of risks that cannot be easily quantified and modelled, including some economic risks, impact assessment modelling should be complemented with qualitative research and active stakeholder engagement. A systematic risk elicitation facilitates communication with stakeholders, enables better risk mitigation, and increases the chance of a sustainable transition.
- Published
- 2020
37. The desirability of transitions in demand: Incorporating behavioural and societal transformations into energy modelling
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Nikas, A., Lieu, J., Sorman, A., Gambhir, A., Turhan, E., Baptista, B.V., Doukas, H., Nikas, A., Lieu, J., Sorman, A., Gambhir, A., Turhan, E., Baptista, B.V., and Doukas, H.
- Abstract
Quantitative systems modelling in support of climate policy has tended to focus more on the supply side in assessing interactions among technology, economy, environment, policy and society. By contrast, the demand side is usually underrepresented, often emphasising technological options for energy efficiency improvements. In this perspective, we argue that scientific support to climate action is not only about exploring capacity of what , in terms of policy and outcome, but also about assessing feasibility and desirability, in terms of when , where and especially for whom . Without the necessary behavioural and societal transformations, the world faces an inadequate response to the climate crisis challenge. This could result from poor uptake of low-carbon technologies, continued high-carbon intensive lifestyles, or economy-wide rebound effects. For this reason, we propose a framing for a holistic and transdisciplinary perspective on the role of human choices and behaviours in influencing the low-carbon transition, starting from the desires of individuals and communities, and analysing how these interact with the energy and economic landscape, leading to systemic change at the macro-level. In making a case for a political ecology agenda, we expand our scope, from comprehending the role of societal acceptance and uptake of end-use technologies, to co-developing knowledge with citizens from non-mainstream and marginalised communities, and to defining the modelling requirements to assess the decarbonisation potential of shifting lifestyle patterns in climate change and action. © 2020 The Author(s)
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- 2020
38. Propagation of Hauser-Feshbach uncertainty estimates to r-process nucleosynthesis: Benchmark of statistical property models for neutron rich nuclei far from stability
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Nikas, S., Perdikakis, G., Beard, M., Surman, R., Mumpower, M. R., Tsintari, P., Nikas, S., Perdikakis, G., Beard, M., Surman, R., Mumpower, M. R., and Tsintari, P.
- Abstract
Multimessenger observations of the neutron star merger event GW170817 have re-energized the debate over the astrophysical origins of the most massive elements via the r-process nucleosynthesis. A key aspect of such studies is comparing astronomical observations to theoretical nucleosynthesis yields in a meaningful way. To perform realistic nucleosynthesis calculations, understanding the uncertainty in microphysics details such as nuclear reaction rates is as essential as understanding uncertainties in modeling the astrophysical environment. We present an investigation of neutron capture rate calculations' uncertainty away from stability using the Hauser-Feshbach model. We provide a quantitative measure of the calculations' dependability when we extrapolate models of statistical properties to nuclei in an r-process network. We select several level density and gamma-ray strength models appropriate for neutron-capture and use them to calculate the reaction rate for each nucleus in the network. We observe how statistical properties affect the theoretical reaction rates. The rates are then sampled with the Monte Carlo technique and used in network calculations to map the range of possible r-process abundances. The results show that neutron capture rates can vary by a couple of orders of magnitude between calculations. Phenomenological models provide smoother results than semi-microscopic. They cannot, however, reproduce nuclear structure changes such as shell closures. While semi-microscopic models predict nuclear structure effects away from stability, it is not clear that these results are quantitatively accurate. The effect of the uncertainty on r-process yields is large enough to impede comparisons between observation and calculations. Progress in developing better microscopic models of gamma strengths and level densities is urgently needed to improve the fidelity of r-process models., Comment: Submitted to Phys. Rev. C (abstract adapted to arXiV character limit and style)
- Published
- 2020
39. A Simple Model for Portable and Fast Prediction of Execution Time and Power Consumption of GPU Kernels
- Author
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Braun, Lorenz, Nikas, Sotirios, Song, Chen, Heuveline, Vincent, Fröning, Holger, Braun, Lorenz, Nikas, Sotirios, Song, Chen, Heuveline, Vincent, and Fröning, Holger
- Abstract
Characterizing compute kernel execution behavior on GPUs for efficient task scheduling is a non-trivial task. We address this with a simple model enabling portable and fast predictions among different GPUs using only hardware-independent features. This model is built based on random forests using 189 individual compute kernels from benchmarks such as Parboil, Rodinia, Polybench-GPU and SHOC. Evaluation of the model performance using cross-validation yields a median Mean Average Percentage Error (MAPE) of 8.86-52.00% and 1.84-2.94%, for time respectively power prediction across five different GPUs, while latency for a single prediction varies between 15 and 108 milliseconds.
- Published
- 2020
40. Enabling Virtual Memory Research on RISC-V with a Configurable TLB Hierarchy for the Rocket Chip Generator
- Author
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Papadopoulos, Nikolaos Charalampos, Karakostas, Vasileios, Nikas, Konstantinos, Koziris, Nectarios, Pnevmatikatos, Dionisios N., Papadopoulos, Nikolaos Charalampos, Karakostas, Vasileios, Nikas, Konstantinos, Koziris, Nectarios, and Pnevmatikatos, Dionisios N.
- Abstract
The Rocket Chip Generator uses a collection of parameterized processor components to produce RISC-V-based SoCs. It is a powerful tool that can produce a wide variety of processor designs ranging from tiny embedded processors to complex multi-core systems. In this paper we extend the features of the Memory Management Unit of the Rocket Chip Generator and specifically the TLB hierarchy. TLBs are essential in terms of performance because they mitigate the overhead of frequent Page Table Walks, but may harm the critical path of the processor due to their size and/or associativity. In the original Rocket Chip implementation the L1 Instruction/Data TLB is fully-associative and the shared L2 TLB is direct-mapped. We lift these restrictions and design and implement configurable, set-associative L1 and L2 TLB templates that can create any organization from direct-mapped to fully-associative to achieve the desired ratio of performance and resource utilization, especially for larger TLBs. We evaluate different TLB configurations and present performance, area, and frequency results of our design using benchmarks from the SPEC2006 suite on the Xilinx ZCU102 FPGA., Comment: 7 pages, Fourth Workshop on Computer Architecture Research with RISC-V (CARRV2020)
- Published
- 2020
41. Integrated policy assessment and optimisation over multiple sustainable development goals in Eastern Africa
- Author
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Van de Ven, Dirk-Jan Petrus Adrianus, Sampedro, Jon, Johnson, Francis X, Bailis, Rob, Forouli, Aikaterini, Nikas, Alexandros, Yu, Sha, pardo, Guillermo, García de Jalón, Silvestre, Wisel, Marshal, Doukas, Haris, Van de Ven, Dirk-Jan Petrus Adrianus, Sampedro, Jon, Johnson, Francis X, Bailis, Rob, Forouli, Aikaterini, Nikas, Alexandros, Yu, Sha, pardo, Guillermo, García de Jalón, Silvestre, Wisel, Marshal, and Doukas, Haris
- Abstract
Heavy reliance on traditional biomass for household energy in eastern Africa has significant negative health and environmental impacts. The African context for energy access is rather different from historical experiences elsewhere as challenges in achieving energy access have coincided with major climate ambitions. Policies focusing on household energy needs in eastern Africa contribute to at least three sustainable development goals (SDGs): climate action, good health, and improved energy access. This study uses an integrated assessment model to simulate the impact of land policies and technology subsidies, as well as the interaction of both, on greenhouse gas (GHG) emissions, exposure to air pollution and energy access in eastern Africa under a range of socioeconomic pathways. We find that land policies focusing on increasing the sustainable output of biomass resources can reduce GHG emissions in the region by about 10%, but also slightly delay progress in health and energy access goals. An optimised portfolio of energy technology subsidies consistent with a global Green Climate Funds budget of 30 35 billion dollar, can yield another 10% savings in GHG emissions, while decreasing mortality related to air pollution by 20%, and improving energy access by up to 15%. After 2030, both land and technology policies become less effective, and more dependent on the overall development path of the region. The analysis shows that support for biogas technology should be prioritised in both the short and long term, while financing liquefied petroleum gas and ethanol technologies also has synergetic climate, health and energy access benefits. Instead, financing PV technologies is mostly relevant for improving energy access, while charcoal and to a lesser extend fuelwood technologies are relevant for curbing GHG emissions if their finance is linked to land policies. We suggest that integrated policy analysis is needed in the African context for simultaneously reaching progress
- Published
- 2019
42. Identifying optimal technological portfolios for European power generation towards climate change mitigation: A robust portfolio analysis approach
- Author
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Forouli, Aikaterini, Doukas, H., Nikas, A., Sampedro, J., Van de Ven, Dirk-Jan Petrus Adrianus, Forouli, Aikaterini, Doukas, H., Nikas, A., Sampedro, J., and Van de Ven, Dirk-Jan Petrus Adrianus
- Abstract
Here, an integrative approach is proposed to link integrated assessment modelling results from the GCAM model with a novel portfolio analysis framework. This framework comprises a bi-objective optimisation model, Monte Carlo analysis and the Iterative Trichotomic Approach, aimed at carrying out stochastic uncertainty assessment and enhancing robustness. The approach is applied for identifying optimal technological portfolios for power generation in the EU towards climate change mitigation until 2050. The considered technologies include photovoltaics, concentrated solar power, wind, nuclear, biomass and carbon capture and storage, for which different subsidy curves for emissions reduction and energy security are considered. © 2019 Elsevier Ltd
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- 2019
43. Integrated policy assessment and optimisation over multiple sustainable development goals in Eastern Africa
- Author
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Fundamentos del análisis económico I, Ekonomia analisiaren oinarriak I, Van de Ven, Dirk-Jan Petrus Adrianus, Sampedro Martínez de Estívariz, Jon, Johnson, Francis Xavier, Bailis, Rob, Forouli, Aikaterini, Nikas, Alexandros, Yu, Sha, Pardo, Guillermo, García de Jalón, Silvestre, Wise, Marshall, Doukas, Haris, Fundamentos del análisis económico I, Ekonomia analisiaren oinarriak I, Van de Ven, Dirk-Jan Petrus Adrianus, Sampedro Martínez de Estívariz, Jon, Johnson, Francis Xavier, Bailis, Rob, Forouli, Aikaterini, Nikas, Alexandros, Yu, Sha, Pardo, Guillermo, García de Jalón, Silvestre, Wise, Marshall, and Doukas, Haris
- Abstract
Heavy reliance on traditional biomass for household energy in eastern Africa has significant negative health and environmental impacts. The African context for energy access is rather different from historical experiences elsewhere as challenges in achieving energy access have coincided with major climate ambitions. Policies focusing on household energy needs in eastern Africa contribute to at least three sustainable development goals (SDGs): climate action, good health, and improved energy access. This study uses an integrated assessment model to simulate the impact of land policies and technology subsidies, as well as the interaction of both, on greenhouse gas (GHG) emissions, exposure to air pollution and energy access in eastern Africa under a range of socioeconomic pathways. We find that land policies focusing on increasing the sustainable output of biomass resources can reduce GHG emissions in the region by about 10%, but also slightly delay progress in health and energy access goals. An optimised portfolio of energy technology subsidies consistent with a global Green Climate Funds budget of 30-35 billion dollar, can yield another 10% savings in GHG emissions, while decreasing mortality related to air pollution by 20%, and improving energy access by up to 15%. After 2030, both land and technology policies become less effective, and more dependent on the overall development path of the region. The analysis shows that support for biogas technology should be prioritised in both the short and long term, while financing liquefied petroleum gas and ethanol technologies also has synergetic climate, health and energy access benefits. Instead, financing PV technologies is mostly relevant for improving energy access, while charcoal and to a lesser extend fuelwood technologies are relevant for curbing GHG emissions if their finance is linked to land policies. We suggest that integrated policy analysis is needed in the African context for simultaneously reaching progress
- Published
- 2019
44. PCR-based detection of Trichomonas vaginalis, Mycoplasma hominis and the human papillomavirus (HPV) in archival PAP-smears
- Author
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Kiechle, Marion B. (Prof. Dr.), Seifert-Klauss, Vanadin R. (Prof. Dr.), Weirich, Gregor (Priv.-Doz. Dr.), Nikas, Ilias, Kiechle, Marion B. (Prof. Dr.), Seifert-Klauss, Vanadin R. (Prof. Dr.), Weirich, Gregor (Priv.-Doz. Dr.), and Nikas, Ilias
- Abstract
Pap test, a cervical cancer screening tool, can also detect organisms such as Trichomonas vaginalis (T.v.) but not its endosymbiont Mycoplasma hominis (M.h.). This study made use of a microdissection-based multiplex PCR approach that allows morphologic-molecular correlation and improved Pap test’s performance concerning T.v. detection, also correlated M.h. with high-risk HPV types. This protocol could be used in various cytologic applications, such as in the field of targeted cancer therapies., Der Pap-Test dient dem Zervix-Screening, hilft auch Mikroorganismen nachzuweisen, wie Trichomonas vaginalis. Mycoplasma hominis hingegen kann nicht dargestellt werden. Diese Arbeit basiert auf einem molekularen Ansatz, um die Schwächen des Pap-Tests auszugleichen. Die Analyse umfasste auch HPV, um Synergien der genannten Mikroorganismen zu erkennen. Wir fanden eine Überlegenheit der PCR-Methode über mikroskopische Detektion von T.v. und eine Korrelation von Infektionen mit M.h. und high-risk HPV. Unsere Methode könnte auch bei der targeted therapy angewandt werden.
- Published
- 2019
45. Education and CO2 emissions through the macroeconomic lens: Assessing their relationship in developing countries from 1996 to 2014
- Author
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Scheidt, Nikas and Scheidt, Nikas
- Abstract
This thesis investigates the macroeconomic relationship between education and CO2 emissions in developing countries. Building on existing literature, a framework is constructed that tries to identify the links underlying this relationship. Education is postulated to affect CO2 emissions in developing countries indirectly through inducing growth, fostering technological change, driving structural transformation, and influencing demographic change. Furthermore, education is assumed to affect CO2 emissions directly through substituting for energy use and by inducing sustainable behavior. The first two indirect links of growth and technological change are tested indirectly and directly, drawing on a panel of 81 developing countries for the period from 1996 to 2014, and differentiating between the short- and the long-run effect. The empirical analyses show that there is likely a short-run increasing effect of education on the level and intensity of CO2 emissions, whereas a consistent long-run effect could not be found.
- Published
- 2019
46. PCR-based detection of Trichomonas vaginalis, Mycoplasma hominis and the human papillomavirus (HPV) in archival PAP-smears
- Author
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Weirich, Gregor (Priv.-Doz. Dr.), Weirich, Gregor (Priv.-Doz. Dr.);Seifert-Klauss, Vanadin R. (Prof. Dr.);Kiechle, Marion B. (Prof. Dr.), Nikas, Ilias, Weirich, Gregor (Priv.-Doz. Dr.), Weirich, Gregor (Priv.-Doz. Dr.);Seifert-Klauss, Vanadin R. (Prof. Dr.);Kiechle, Marion B. (Prof. Dr.), and Nikas, Ilias
- Abstract
Pap test, a cervical cancer screening tool, can also detect organisms such as Trichomonas vaginalis (T.v.) but not its endosymbiont Mycoplasma hominis (M.h.). This study made use of a microdissection-based multiplex PCR approach that allows morphologic-molecular correlation and improved Pap test’s performance concerning T.v. detection, also correlated M.h. with high-risk HPV types. This protocol could be used in various cytologic applications, such as in the field of targeted cancer therapies., Der Pap-Test dient dem Zervix-Screening, hilft auch Mikroorganismen nachzuweisen, wie Trichomonas vaginalis. Mycoplasma hominis hingegen kann nicht dargestellt werden. Diese Arbeit basiert auf einem molekularen Ansatz, um die Schwächen des Pap-Tests auszugleichen. Die Analyse umfasste auch HPV, um Synergien der genannten Mikroorganismen zu erkennen. Wir fanden eine Überlegenheit der PCR-Methode über mikroskopische Detektion von T.v. und eine Korrelation von Infektionen mit M.h. und high-risk HPV. Unsere Methode könnte auch bei der targeted therapy angewandt werden.
- Published
- 2019
47. High temperature bi-axial low cycle fatigue behaviour of railway wheel steel
- Author
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Dimitrios, Nikas, Ahlström, Johan, Dimitrios, Nikas, and Ahlström, Johan
- Abstract
One of the most important aspects in railway operation is the interaction between rail and wheel. Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with some 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads are evolved because of recurring braking and occasional slippage. Thus the combination of mechanical and thermal loads leads to changes in the mechanical properties of the material. The focus of the current investigation is to evaluate the mechanical behaviour of wheel material (UIC ER7T) subjected to non-proportional biaxial fatigue loading, as this simulates the actual working conditions in a better way than uniaxial loading. Axial-torsional low cycle fatigue tests were performed at room temperature and elevated temperatures using thin walled specimens to study the cyclic stress-strain properties of this material. The results showed large influence of temperature on the ratcheting behaviour of the material. Biaxial non-proportional loading gave much higher strain hardening as compared to uniaxial loading. Hardening due to dynamic strain ageing can be seen in the biaxial tests at temperatures around 300 degrees C.
- Published
- 2019
- Full Text
- View/download PDF
48. Narratives of Low-Carbon Transitions: Understanding Risks and Uncertainties
- Author
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Hanger-Kopp, S., Lieu, J., Nikas, A., Hanger-Kopp, S., Lieu, J., and Nikas, A.
- Abstract
This book examines the uncertainties underlying various strategies for a low-carbon future. Most prominently, such strategies relate to transitions in the energy sector, on both the supply and the demand side. At the same time they interact with other sectors, such as industrial production, transport, and building, and ultimately require new behaviour patterns at household and individual levels. Currently, much research is available on the effectiveness of these strategies but, in order to successfully implement comprehensive transition pathways, it is crucial not only to understand the benefits but also the risks. Filling this gap, this volume provides an interdisciplinary, conceptual framework to assess risks and uncertainties associated with low-carbon policies and applies this consistently across 11 country cases from around the world, illustrating alternative transition pathways in various contexts. The cases are presented as narratives, drawing on stakeholder-driven research efforts. They showcase diverse empirical evidence reflecting the complex challenges to and potential negative consequences of such pathways. Together, they enable the reader to draw valuable lessons on the risks and uncertainties associated with choosing the envisaged transition pathways, as well as ways to manage the implementation of these pathways and ultimately enable sustainable and lasting social and environmental effects. This book will be of great interest to students, scholars, and practitioners of environmental and energy policy, low-carbon transitions, renewable energy technologies, climate change action, and sustainability in general. Share this Title
- Published
- 2019
49. Switzerland: Risks of implementing a national energy strategy: Understanding Risks and Uncertainties
- Author
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Research Support Office, Hanger- Kopp, S., Lieu, J., Nikas, A., van Vliet, O.P.R., Research Support Office, Hanger- Kopp, S., Lieu, J., Nikas, A., and van Vliet, O.P.R.
- Published
- 2019
50. Switzerland: Risks associated with implementing a national energy strategy
- Author
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Research Support Office, Hanger-Kopp, Susanne, Lieu, Jenny, Nikas, Alexandros, van Vliet, Oscar P.R., Research Support Office, Hanger-Kopp, Susanne, Lieu, Jenny, Nikas, Alexandros, and van Vliet, Oscar P.R.
- Published
- 2019
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