| 171. |
- Adlarson, Patrik, et al.
(författare)
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Search for eta-mesic He-4 with the WASA-at-COSY detector
- 2013
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:3, s. 035204-
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Tidskriftsartikel (refereegranskat)abstract
- An exclusive measurement of the excitation function for the dd -> (3)Hep pi(-) reaction was performed at the Cooler Synchrotron COSY-Julich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 to 2.400 GeV/c crossing the kinematic threshold for the eta-meson production in the dd -> He-4 eta reaction at 2.336 GeV/c. The corresponding excess energy with respect to the He-4-eta system varied from -51.4 to 22 MeV. The integrated luminosity in the experiment was determined using the dd -> (3)Hen reaction. The shape of the excitation function for the dd -> (3)Hep pi(-) reaction was examined. No signal of the He-4-eta bound state was observed. An upper limit for the cross section for the bound state formation and decay in the process dd -> (He-4-eta)(bound) -> (3)Hep pi(-) was determined on the 90% confidence level and it varies from 20 to 27 nb for the bound state width ranging from 5 to 35 MeV, respectively.
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| 172. |
- Cameron, Sarina R., et al.
(författare)
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PTE, a novel module to target Polycomb Repressive Complex 1 to the human cyclin D2 (CCND2) oncogene
- 2018
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 293:37, s. 14342-14358
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Tidskriftsartikel (refereegranskat)abstract
- Polycomb group proteins are essential epigenetic repressors. They form multiple protein complexes of which two kinds, PRC1 and PRC2, are indispensable for repression. Although much is known about their biochemical properties, how mammalian PRC1 and PRC2 are targeted to specific genes is poorly understood. Here, we establish the cyclin D2 (CCND2) oncogene as a simple model to address this question. We provide the evidence that the targeting of PRC1 to CCND2 involves a dedicated PRC1-targeting element (PTE). The PTE appears to act in concert with an adjacent cytosine-phosphate-guanine (CpG) island to arrange for the robust binding of PRC1 and PRC2 to repressed CCND2. Our findings pave the way to identify sequence-specific DNA-binding proteins implicated in the targeting of mammalian PRC1 complexes and provide novel link between polycomb repression and cancer.
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| 173. |
- Moksnes, Nandi, et al.
(författare)
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Determinants of energy futures—a scenario discovery method applied to cost and carbon emission futures for South American electricity infrastructure
- 2019
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Ingår i: Environmental Research Communications (ERC). - : IOP Publishing. - 2515-7620. ; 02:5001
-
Tidskriftsartikel (refereegranskat)abstract
- Energy policy and investment are commonly informed by a small number of scenarios, modelled with proprietary models and closed data-sets. It limits what levels of insight that can be derived from it. This paper overcomes these critical concerns by exploring a large number of scenarios with an open-data and open-source model to address regional mitigation policy. Focusing on South America, we translate an ensemble of long-term electricity supply scenarios into policy insights and use post-processing methods to present a systematic mapping of solution outputs to model inputs. We find demand levels, the cost of capital and the level of CO2-limits to be significant determinants of total investment cost. Low-carbon pathways are associated with low demand and low cost of capital. When cost of capital increases a shift away from wind and hydropower to natural gas and solar PV is seen. We further show that appropriate concessionary finance together with energy efficiency measures are critical—at a continental level—to unlock economic, low-carbon investment.
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| 174. |
- Moksnes, Nandi, et al.
(författare)
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Electrification pathways for Kenya-linking spatial electrification analysis and medium to long term energy planning
- 2017
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Ingår i: Environmental Research Letters. - : Institute of Physics Publishing (IOPP). - 1748-9326. ; 12:9
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Tidskriftsartikel (refereegranskat)abstract
- In September 2015 UN announced 17 Sustainable Development goals (SDG) from which goal number 7 envisions universal access to modern energy services for all by 2030. In Kenya only about 46% of the population currently has access to electricity. This paper analyses hypothetical scenarios, and selected implications, investigating pathways that would allow the country to reach its electrification targets by 2030. Two modelling tools were used for the purposes of this study, namely OnSSET and OSeMOSYS. The tools were soft-linked in order to capture both the spatial and temporal dynamics of their nature. Two electricity demand scenarios were developed representing low and high end user consumption goals respectively. Indicatively, results show that geothermal, coal, hydro and natural gas would consist the optimal energy mix for the centralized national grid. However, in the case of the low demand scenario a high penetration of stand-alone systems is evident in the country, reaching out to approximately 47% of the electrified population. Increasing end user consumption leads to a shift in the optimal technology mix, with higher penetration of mini-grid technologies and grid extension.
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| 175. |
- Moksnes, Nandi, et al.
(författare)
-
Electrification pathways for Kenya-linking spatial electrification analysis and medium to long term energy planning (vol 12, 095008, 2017)
- 2020
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 15:12
-
Tidskriftsartikel (refereegranskat)abstract
- We have identified input values that were not harmonized with the paper and have therefore submitted this corrigendum. Qualitatively, there are no major differences between the two versions, and the insights generated are unchanged. However, part of the results, figures and discussion needed to be updated based on the new findings. We present those in the form of a corrigendum. In the model runs there were input parameters that were not harmonized with the published paper as seen in annex in table 1. Therefore, to amend the incurred values, we have re-run the model and updated the following sections of the paper.
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| 176. |
- Moksnes, Nandi, 1982-
(författare)
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Exploring spatial and temporal resolution in energy systems modelling : a model-based analysis focused on the developing electricity systems
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The energy system is undergoing a transition in many parts of the world with this transition being driven by several factors such as climate change, and economic and social development. Agenda 2030, with its 17 Sustainable Development Goals (SDGs), has set the direction on where development should be focussed. There are still around 675 million people who lack access to electricity (SDG7), mainly in Sub-Saharan Africa. The energy system is also responsible for emitting most greenhouse gas (GHG) emissions and is closely connected to SDG 13, climate action.Energy models can provide insight into the implications of different interventions in the system. However, the transition also poses new challenges for energy modelling. New spatiotemporal questions arise with 1) the penetration of renewable technologies to mitigate GHG emissions, with location-specific intermittent supply options such as wind and solar PV panels, and 2) the low share of the population living near the existing electricity network in many Sub-Saharan countries and the decreasing cost of off-grid and mini-grid supply options.This change increases the number of technologies and details needed in the system which in turn increases complexity in the models. Complexity can be defined in terms of four aspects: spatial, temporal, mathematical and, system scope. However, more detail, both parametrical and structural, can introduce more potential errors and uncertainty into the model. Therefore, energy models should be as simple as possible and as complex as necessary.This thesis aims to give quantifiable and qualitative insights into the mathematical, spatial, and temporal aspects of energy systems modelling for both national and regional system scopes, along with their policy implications. The thesis explores the trade-offs between which mathematical method is applied when modelling electricity access, and the global sensitivity of parametrical and structural parameters in ESOMs.The method for achieving the aim of the thesis uses a four-step approach. First, the geospatial electrification problem is explored by developing two different models, a linear programming model, using the model generator GEOSeMOSYS, and a heuristic method, soft-linking the open-source tools OnSSET and OSeMOSYS. Second, these two models are compared in order to understand the differences between them with respect to computational effort, results, insight, and effectiveness in modelling electricity access in a developing country. Third, the linear programming model developed for this thesis is then explored using the method of Morris global sensitivity analysis to understand the importance of spatial and temporal resolution compared to other parameters such as demand, discount rate, and capital cost. Fourth and finally, the global sensitivity analysis method of factor mapping, using scenario discovery, is explored to understand parameters that determine cost and low carbon futures in the regional multi-country energy systems optimisation model ‘South America Model Base’ (SAMBA).The results show that the two methods for optimising electrification show similar trends when the demand is changed, with low demand predominantly resulting in PV panels and batteries to serve the formerly unelectrified population, while higher demand results in more grid-connected households. The demand level and profile for newly electrified households result in different service levels and possibilities for adding more appliances over time. The competitiveness of PV panels with batteries decreases significantly when the demand profile increases during the night. The two methods in this thesis have different solution times with the linear programming method having a much longer solution time, furthermore, the mathematical approaches to solve the transmission network are different, and both methods have trade-offs in their results. These trade-offs are in the mathematical approach where OnSSET uses a one-at-the-time optimisation leading to a suboptimal overall network, and GEOSeMOSYS rely on the assumption of linearity, which leads to very small incremental installations of transmission lines.The global sensitivity analysis of GEOSeMOSYS for electricity access showed that the structural parameters, spatial and temporal resolution, influence the result parameters and cannot be simplified without changing the results. The temporal resolution had a greater influence on the assessed results parameters than the spatial resolution, indicating that it is more significant. For the South American system, the parameters that determine low carbon emission pathways are low/medium demand and low/medium discount rates.This thesis has therefore shown that, even though models should be as simple as possible, the spatial and temporal resolution cannot be simplified to a one-node analysis or low temporal resolution without this affecting the results. The mathematical choice for selecting the method of electricity access was analysed and trade-offs were highlighted. The main trade-off was in the network expansion where both methods use approximations that can lead to over/underestimating the investment need. The soft-linked method is a good option to understand a higher level to explore electricity access. If the question is more complex (e.g., adding transportation, heating and cooling), then GEOSeMOSYS provides more readily available options for expanding the analysis, but at a coarse spatial resolution. Demand is a critical parameter in energy models, as is shown in this thesis, and determines both the cost and the potential for achieving low carbon futures. Therefore, including more demand functionalities (such as demand side management and price elasticity) in energy models could help to further detail future demands, and this is identified as future work.
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| 177. |
- Nandi, A., et al.
(författare)
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Accretion flow dynamics during 1999 outburst of XTE J1859+226—modeling of broadband spectra and constraining the source mass
- 2018
-
Ingår i: Astrophysics and Space Science. - : Springer Netherlands. - 0004-640X .- 1572-946X. ; 363:5
-
Tidskriftsartikel (refereegranskat)abstract
- We examine the dynamical behavior of accretion flow around XTE J1859+226 during the 1999 outburst by analyzing the entire outburst data (∼166 days) from RXTE Satellite. Towards this, we study the hysteresis behavior in the hardness intensity diagram (HID) based on the broadband (3–150 keV) spectral modeling, spectral signature of jet ejection and the evolution of Quasi-periodic Oscillation (QPO) frequencies using the two-component advective flow model around a black hole. We compute the flow parameters, namely Keplerian accretion rate (m˙ d), sub-Keplerian accretion rate (m˙ h), shock location (rs) and black hole mass (Mbh) from the spectral modeling and study their evolution along the q-diagram. Subsequently, the kinetic jet power is computed as Ljetobs∼3–6×1037ergs−1 during one of the observed radio flares which indicates that jet power corresponds to 8–16% mass outflow rate from the disc. This estimate of mass outflow rate is in close agreement with the change in total accretion rate (∼14%) required for spectral modeling before and during the flare. Finally, we provide a mass estimate of the source XTE J1859+226 based on the spectral modeling that lies in the range of 5.2–7.9 M⊙ with 90% confidence.
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| 178. |
- Nandi, Ganesh C., et al.
(författare)
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Pd-catalyzed C-N coupling of vinylbromides and sulfonimidamides : a facile synthesis of N '-vinylsulfonimidamides
- 2015
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 5:76, s. 62084-62090
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Tidskriftsartikel (refereegranskat)abstract
- N'-Vinyl sulfonimidamides have been synthesized through a Pd-catalyzed C-N cross coupling between the N'-(imine nitrogen) of N'-deprotected sulfonimidamides and vinyl bromides. The hitherto unreported products were obtained in moderate to excellent yield, and the C-C double bond geometry of the vinylic substrates were retained during the course of reaction. Single crystal X-ray crystallographic analysis confirmed the product structure. Furthermore, we demonstrate that the formed N'-vinyl sulfonimidamides could undergo hydrogenation with Pd-C/H-2 to provide N'-alkyl sulfonimidamides.
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| 179. |
- Ramos, Eunice, et al.
(författare)
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The role of energy efficiency in the management of water resources of the Syr Darya River basin
- 2021
-
Ingår i: International Journal of Environment and Sustainable Development (IJESD). - : INDERSCIENCE ENTERPRISES LTD. - 1474-6778 .- 1478-7466. ; 20:1, s. 64-88
-
Tidskriftsartikel (refereegranskat)abstract
- A motivation for integrated resource assessments is that they can capture indirect cross-sectoral effects of sectoral policies. This work investigates the electricity system implications from the implementation of basin-wide electricity and water systems efficiency measures. The spatial scope includes the four states that share the Syr Darya River basin. Different interests dictate the management of water resources in the basin. They are necessary for irrigation downstream in spring and summer and upstream, for hydropower generation during winter. The study investigated options to decrease the need for electricity upstream through efficiency measures and by the expansion of regional electricity trade. The scenarios were simulated by developing a multi-country electricity system model using the open source energy modelling system (OSeMOSYS). The results show that lesser investments in hydropower capacity could be needed and less water required in winter. This would reduce pressure on shared water resources.
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