Naresuan University Journal
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Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources
No full textModels of the dynamics of eruptive degassing provide a unique insight into the pre-eruptive concentrations of the major volatiles (CO2, H2O), noble gases, and the mantle reservoirs supplying them: a fundamental component in describing the accretion and evolution of the Earth. We investigate and develop a disequilibrium degassing model, exploring the parameters required to reproduce noble gas compositions observed in two ocean island basalt (OIB) and one mid-ocean ridge basalt (MORB) sample suites from the East Pacific Rise (EPR), Loihi Seamount, and Iceland. The original model assumed an identical loss of major volatile components for each degassing step (Gonnermann and Mukhopadhyay, 2007). We recalculate the major volatile vapor phase composition for each degassing step, taking account of the degassing history over previous steps. Final noble gas elemental ratios, using the same eruption parameters, can differ by orders of magnitude from the original model's calculations. We further adapt our model variant to take into account both decompression-driven degassing during magma ascent and degassing at constant pressure during sample quenching. Our results show that elemental ratios and noble gas concentrations can be effectively decoupled by the different degassing stages of an eruption. Ascent rate determines whether degassing during magma ascent is modeled as predominantly closed or open system degassing. The closed system conditions that dominate the slowly ascending MORB result in a less dramatic decrease in degassed elemental ratios than for the OIB models, consistent with the observed data. The MORB model also constrains the initial MORB source melt 3He/22Ne ratio, allowing that the MORB mantle could have a ratio as low as the OIB ratio, a feature required by steady state mantle models. The two OIB sample suites show very similar noble gas ratios and concentrations despite a large difference in final eruption pressures. We propose that this can fit our model if the effect of gas loss by quenching is negligible. Our model then shows that only a small amount of degassing takes place during magma ascent, meaning that initial OIB He melt concentrations must be similar to or lower than MORB source melt concentrations, although greater initial CO2 concentrations are required. This result is entirely consistent with mantle models which see a significant recycled component in the OIB-source mantle: such material would be expected to have higher CO2 but lower 3He concentrations than the depleted mantle
Ancillary Service for Transmission Systems by Tap Stagger Operation in Distribution Networks
No full textWith the integration of intermittent renewable generation, transmission voltage problems have become more dynamic. The deployment and tuning of numbers of VAr compensators at various locations may not be cost-effective. This paper presents an alternative method, which utilises existing parallel transformers in distribution networks, to provide reactive power absorption services for transmission systems with low demands. The operation of parallel transformers in small different tap positions, i.e. with staggered taps, can provide a means of absorbing reactive power. The aggregated VAr absorption from many pairs of parallel transformers could be used to provide voltage support to the upstream transmission network. This paper focuses on both the economic and technical analyses of using the tap staggering method. For the economic analysis, the associated costs of applying the tap staggering technique are investigated through static load flow studies. The IEEE Reliability Test System is used to carry out the studies and the results are compared with the installation of shunt reactors. In the technical studies, the dynamic impacts of tap staggering or reactor switching on transmission voltages are analysed. From the results, the tap staggering technique has more economic advantages than reactors and can reduce the voltage damping and overshoots during the transient states
A multi-dimensional assessment of urban vulnerability to climate change in Sub-Saharan Africa
No full textIn this paper, we develop and apply a multi-dimensional vulnerability assessment framework for understanding the impacts of climate change-induced hazards in Sub-Saharan African cities. The research was carried out within the European/African FP7 project CLimate change and Urban Vulnerability in Africa, which investigated climate change-induced risks, assessed vulnerability and proposed policy initiatives in five African cities. Dar es Salaam (Tanzania) was used as a main case with a particular focus on urban flooding. The multi-dimensional assessment covered the physical, institutional, attitudinal and asset factors influencing urban vulnerability. Multiple methods were applied to cover the full range of vulnerabilities and to identify potential response strategies, including: model-based forecasts, spatial analyses, document studies, interviews and stakeholder workshops. We demonstrate the potential of the approach to assessing several dimensions of vulnerability and illustrate the complexity of urban vulnerability at different scales: households (e.g., lacking assets); communities (e.g., situated in low-lying areas, lacking urban services and green areas); and entire cities (e.g., facing encroachment on green and flood-prone land). Scenario modeling suggests that vulnerability will continue to increase strongly due to the expected loss of agricultural land at the urban fringes and loss of green space within the city. However, weak institutional commitment and capacity limit the potential for strategic coordination and action. To better adapt to urban flooding and thereby reduce vulnerability and build resilience, we suggest working across dimensions and scales, integrating climate change issues in city-level plans and strategies and enabling local actions to initiate a ‘learning-by-doing’ process of adaptation
Youth justice: Past, present and future
No full textIn contemporary youth justice in England and Wales, there is too much emphasis on offence- and offender- focused approaches and an insufficient focus on promoting positive outcomes for children in conflict with the law. What is more, since the Crime and Disorder Act 1998, the voices of children embroiled in the Youth Justice System have been marginalised and their participatory rights rendered invalid. Both children and Youth Offending Team workers are finding involvement in the Youth Justice System (e.g. assessment, planning, intervention, supervision and review) to be a disempowering and disengaging experience. In this paper, we outline a number of contemporary tensions and conflicts in relation to youth justice law, policy and practice: the highly political context of youth justice, the criminalising risk, prevention and early intervention agendas and the unique and specialised nature of youth justice services. We also introduce a focus for future developments and 'creative possibilities' for youth justice. Specifically, we advocate for Children First, Offenders Second (CFOS), a progressive and principled model of youth justice that advocates for child sensitive, child appropriate services, diversion and the promotion of positive behaviours and outcomes for children, underpinned by evidence-based partnership working and the engagement of children (and parents) at all stages of the youth justice process
Carbon capture, storage and utilisation of technologies: A critical analysis and comparison of their life cycle environmental impacts
No full textThis paper presents a first comprehensive comparison of environmental impacts of carbon capture and storage (CCS) and carbon capture and utilisation (CCU) technologies. Life cycle assessment studies found in the literature have been reviewed for these purposes. In total, 27 studies have been found of which 11 focus on CCS and 16 on CCU. The CCS studies suggest that the global warming potential (GWP) from power plants can be reduced by 63–82%, with the greatest reductions achieved by oxy-fuel combustion in pulverised coal and integrated gasification combined cycle (IGCC) plants and the lowest by postcombustion capture in combined cycle gas turbine (CCGT) plants. However, other environmental impacts such as acidification and human toxicity are higher with than without CCS. For CCU, the GWP varies widely depending on the utilisation option. Mineral carbonation can reduce the GWP by 4–48% compared to no CCU. Utilising CO2 for production of chemicals, specifically, dimethylcarbonate (DMC) reduces the GWP by 4.3 times and ozone layer depletion by 13 times compared to the conventional DMC process. Enhanced oil recovery has the GWP 2.3 times lower compared to discharging CO2 to the atmosphere but acidification is three times higher. Capturing CO2 by microalgae to produce biodiesel has 2.5 times higher GWP than fossil diesel with other environmental impacts also significantly higher. On average, the GWP of CCS is significantly lower than of the CCU options. However, its other environmental impacts are higher compared to CCU except for DMC production which is the worst CCU option overall
Phosphorylation of Synaptic GTPase Activating Protein (synGAP) by Ca2+/Calmodulin-dependent Protein Kinase II (CaMKII) and Cyclin-dependent Kinase 5 (CDK5) Alters the Ratio of its GAP Activity Toward Ras and Rap GTPases
No full textDEP2SA: A Decentralised Efficient Privacy-Preserving and Selective Aggregation Scheme in Advanced Metering Infrastructure
No full textThis paper proposes a novel solution, called a decentralised, efficient, privacy-preserving and selective aggregation (DEP2SA) scheme, designed to support secure and user privacy-preserving data collection in the advanced metering infrastructure. DEP2SA is more efficient and applicable in real-life deployment, as compared with the state of the art, by adopting and adapting a number of key technologies: (1) it uses a multi-recipient system model, making it more applicable to a liberalised electricity market; (2) it uses the homomorphic Paillier encryption and selective aggregation methods to protect users’ consumption data against both external and internal attacks, thus making it more secure; (3) it aggregates data at the gateways that are closest to the data originator, thus saving bandwidth and reducing the risk of creating a performance bottleneck in the system; and (4) it uses short signature and batch signature verification methods to further reduce computational and communication overheads imposed on aggregating nodes. The scheme has been analysed in terms of security, computational and communication overheads, and the results show that it is more secure, efficient and scalable than related schemes
Renal Mechanisms of Association between Fibroblast Growth Factor 1 and Blood Pressure.
No full textThe fibroblast growth factor 1 (FGF1) gene is expressed primarily in the kidney and may contribute to hypertension. However, the biologic mechanisms underlying the association between FGF1 and BP regulation remain unknown. We report that the major allele of FGF1 single nucleotide polymorphism rs152524 was associated in a dose-dependent manner with systolic BP (P=9.65×10(-5)) and diastolic BP (P=7.61×10(-3)) in a meta-analysis of 14,364 individuals and with renal expression of FGF1 mRNA in 126 human kidneys (P=9.0×10(-3)). Next-generation RNA sequencing revealed that upregulated renal expression of FGF1 or of each of the three FGF1 mRNA isoforms individually was associated with higher BP. FGF1-stratified coexpression analysis in two separate collections of human kidneys identified 126 FGF1 partner mRNAs, of which 71 and 63 showed at least nominal association with systolic and diastolic BP, respectively. Of those mRNAs, seven mRNAs in five genes (MME, PTPRO, REN, SLC12A3, and WNK1) had strong prior annotation to BP or hypertension. MME, which encodes an enzyme that degrades circulating natriuretic peptides, showed the strongest differential coexpression with FGF1 between hypertensive and normotensive kidneys. Furthermore, higher level of renal FGF1 expression was associated with lower circulating levels of atrial and brain natriuretic peptides. These findings indicate that FGF1 expression in the kidney is at least under partial genetic control and that renal expression of several FGF1 partner genes involved in the natriuretic peptide catabolism pathway, renin-angiotensin cascade, and sodium handling network may explain the association between FGF1 and BP
ALMA observations of 99 GHz free-free and H40α line emission from star formation in the centre of NGC 253
No full textWe present Atacama Large Millimeter/submillimeter Array observations of 99.02 GHz free-free and H40α emission from the centre of the nearby starburst galaxy NGC 253. We calculate electron temperatures of 3700-4500 K for the photoionized gas, which agrees with previous measurements. We measure a photoionizing photon production rate of (3.2 ± 0.2) × 1053 s-1 and a star formation rate of 1.73 ± 0.12 M⊙ yr-1 within the central 20 × 10 arcsec, which fall within the broad range of measurements from previous millimetre and radio observations but which are better constrained. We also demonstrate that the dust opacities are ˜3 dex higher than inferred from previous near-infrared data, which illustrates the benefits of using millimetre star formation tracers in very dusty sources