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Item type: Publication , Access status: Metadata only , Non-alkali metals titrate silica out of carbonatite melts into insoluble silicate minerals(2026-01-15) Zhu, Xinxiang; Anenburg, Michael; Liu, YanSilica solubility in crustal carbonatite melts is a controversial topic with suggested solubility limits varying wildly from nearly 0 % up to 15 % SiO2. Here, we present experiments utilising alumina crucibles and CO2 atmospheres. We tested low pressure phase relations and compositions in simplified Na-K-Ca-Fe3+-Al-Si-F systems. We found that substantial mutual solubility of CaO and SiO2 was not possible. Instead, they reacted to form combeite and other Na-Ca silicates. Kalsilite formed on crucible walls, and occasionally within the liquid pools. In Fe2O3-rich systems, SiO2 was likewise poorly soluble in the carbonatite melt with both components partitioning to separate silicate phases. Silica is substantially soluble in carbonatite melts only if they contain Na2O or K2O and no other non-alkali cations that can react with SiO2 to form refractory silicates. In these alkali-dominated systems, immiscible silicate liquids form in equilibrium with Si-bearing, Ca-poor carbonatite melts. Our findings agree with experimentally-derived carbonatite compositions obtained over the past several decades, particularly in decreasing temperatures and increasing alkali regimes. The Ca-poor character of both experimental immiscible liquids may explain the unusual alkali-rich composition of carbonatites and nephelinites in Oldoinyo Lengai, formed at near-atmospheric pressures. Since virtually all natural carbonatite melts contain much more Ca (and other non-alkali metals such as Mg or Fe) than Si, actual natural melt compositions will be SiO2-free for all practical purposes at temperatures below approximately 1000 degrees C, resulting from SiO2 being titrated out to refractory silicates. We propose that low-temperature silicocarbonatites are likely to be antiskarns, igneous silicate mineral assemblages within carbonatites where SiO2 was externally supplied by adjacent silicate rocks. Likewise, we suggest that many carbonatite-associated silicate rocks in ring complexes did not entirely form as cumulates from SiO2-bearing carbonatite melts. Instead, some formation by antiskarn metasomatism is a plausible mechanism. We suggest that currently-observed quartz in carbonatites forms post-magmatically. Therefore, previously hypothesised silica-dependent ore-forming processes may not occur in natural carbonatites, because SiO2 cannot attain sufficient concentrations in primary carbonatitic melts and mineralising fluids.Item type: Publication , Access status: Metadata only , Ecology in Africa: historical perspectives, present state and prospects(2025) Owuor, Margaret Awuor; Seehausen, Ole; Borokini, Israel Temitope; Abila, Romulus; Githiora, Yvonne Wambui; Speranza, Chinwe Ifejika; Njau, Michael Gabriel; Ngila, Peggy; Chiawo, David; Valenzano, Dario Riccardo; Gross, RachaelEcology research, education and conservation policies in Africa are heavily influenced by western science and philosophy, resulting in the marginalization of African traditional ecological knowledge (TEK) systems. This legacy persists in post-colonial African government structures and academic institutions, influencing teaching methodologies, research approaches, and conservation policy frameworks. These challenges are further exacerbated by funding dynamics that promote parachute science, hindering the intellectual empowerment of African scientists. To address these challenges, we organized a symposium during the 2022 International Conference on Ecology on, “Ecology in Africa: present and future prospects”. Presenters identified several areas within three domains – ecology education, research, and policy – that need attention. Suggested solutions include decolonizing ecology research, introducing transformative curricula that integrate TEK and modernized pedagogies in ecology teaching, increasing government funding for ecology research and education, promoting regional and transboundary research collaborations, and engagement with the African Diasporan experts. Community-based conservation that generates benefits to Indigenous and local communities, and policy interventions by and with African governments, with stable administrative structures for effective policy implementation are also required. Effective implementation of these recommendations by African governments and other actors is necessary to reverse the brain drain, ensure quality ecology education to boost research and conservation, empower local experts, promote ethical and equitable research collaborations, and prepare ecology students for addressing the challenges of biodiversity loss, ecosystem degradation and climate change.Item type: Publication , Access status: Metadata only , Climate change is leaving African elephants desperate for water(2023-06-01) Gross, Rachael B; Heinsohn, RobertItem type: Publication , Access status: Metadata only , Depressive symptoms among senior citizens in Baijanath Rural Municipality, Nepal: a community-based cross-sectional study(2025-12-11) Darlami, Lejain; Poudel, Sujan; Khatri, Dhurba; Paudel, Sadhiksha; Marasine, Nirmal Raj; Paudel, ShishirBackground Depression among senior citizens is a growing public health concern, particularly in low-and middle-income countries (LMICs), where aging populations often experience multiple socio-economic and health-related vulnerabilities. In Nepal, community-based evidence on geriatric depression, especially in rural areas, remains limited. This study aimed to assess the frequency of depressive symptoms and to identify associated factors among senior citizens residing in rural communities of Nepal. Methods A cross-sectional study was conducted among 205 senior citizens (aged >= 60 years) residing in Baijanath Rural Municipality. Data were collected through face-to-face interviews using a semi-structured questionnaire where Geriatric Depression Scale-15 (GDS-15) was used to assess depressive symptoms. Bivariate analysis using Pearson's chi-square test and multivariable logistic regression were conducted to identify factors associated with geriatric depression. Results were presented as the adjusted odds ratio (aOR) with 95% confidence intervals (CI), where statistical significance was set atp<0.05. Results More than half (52.70%, 95% CI:46.00%-59.30%) of the study participants exhibited depressive symptoms. The factors significantly associated with depression included Janajati ethnicity (aOR: 0.41; 95% CI: 0.18-0.93), poor economic status (1st and 2nd quintiles: aOR = 2.99 and 2.89, respectively), presence of multiple morbidities (aOR: 6.44; 95% CI: 2.51-16.53), and impaired physical functioning (aOR: 3.25; 95% CI: 1.09-9.60). No significant associations were found between depressive symptoms and the alcohol or tobacco used by their offspring. Conclusion This study highlights a substantial burden of depressive symptoms among senior citizens residing in a rural community of Nepal and highlights key associated factors, including economic hardship, multimorbidity, and physical dependency. Targeted interventions focusing on chronic disease management, physical rehabilitation, and economic support are critical to improving mental health among senior citizens in rural settings.Item type: Publication , Access status: Metadata only , Can international financial assistance drive the clean energy transition in developing countries?(2026) Bui, Manh-Tien; Le, Thai-HaIn this study, we investigated the role of international financial assistance in promoting clean energy development and environmental sustainability across 89 developing countries from 2000 to 2021. Using a Panel ARDL model with the Pooled Mean Group (PMG) estimator, assesses assessed the short-and long-run effects of global financial flows directed toward clean energy research, development, and production (RD&P). The findings revealed that while international financial assistance contributes to reductions in CO2 emissions in the long run, its influence on the renewable energy share in total energy supply remains weak and statistically insignificant. This outcome reflects the structural challenges facing developing economies, particularly rapid energy demand growth driven by industrialization and limited absorptive capacity for green technologies. The results further highlight the critical role of governance quality in shaping the effectiveness of external finance: Stronger governance systematically amplifies environmental returns in upper-income economies while influencing the relationship differently in lower-income settings. Policy implications suggest that international support should not only increase in scale but also be better targeted and better governed, emphasizing system-enabling investments, institutional strengthening, and long-term policy alignment to ensure a sustained and inclusive clean-energy transition.