A typology of marine and estuarine hazards and risks as vectors of change : a review for vulnerable coasts and their management

This paper illustrates a typology of 14 natural and anthropogenic hazards, the evidence for their causes and consequences for society and their role as vectors of change in estuaries, vulnerable coasts and marine areas. It uses hazard as the potential that there will be damage to the natural or human system and so is the product of an event which could occur and the probability of it occurring whereas the degree of risk then relates to the amount of assets, natural or societal, which may be affected. We give long- and short-term and large- and small-scale perspectives showing that the hazards leading to disasters for society will include flooding, erosion and tsunamis. Global examples include the effects of wetland loss and the exacerbation of problems by building on vulnerable coasts. Hence we emphasise the importance of considering hazard and risk on such coasts and consider the tools for assessing and managing the impacts of risk and hazard. These allow policy-makers to determine the consequences for natural and human systems. We separate locally-derived problems from large-scale effects (e.g. climate change, sea-level rise and isostatic rebound); we emphasise that the latter unmanaged exogenic pressures require a response to the consequences rather than the causes whereas within a management area there are endogenic managed pressures in which we address both to causes and consequences. The problems are put into context by assessing hazards and the conflicts between different uses and users and hence the management responses needed. We emphasise that integrated and sustainable management of the hazards and risk requires 10-tenets to be fulfilled

Corruption in Uganda: A Comparative Study of Citizens’ and Public Officials’ Perceptions

The findings of this study into the complex problem of corruption in Uganda dispel the pervasive and popular view that corruption in East Africa’s third largest economy is an exclusive behavior monopolized by public officials. This study finds that corruption is engendered by an unholy alliance between citizens desperate to access services and public officials eager to exact a price on services they are obliged to freely provide. This study determined that corruption in Uganda largely depends upon collaboration by citizens and public officials, hence changing the simplest meaning of corruption from the abuse of public office to an act that benefits the community. Using the Institutional Analysis and Development framework (IAD), the primary purpose of this quantitative comparative study was to examine to what extent citizens and public officials differed in levels of their perception of corruption and the degree of the forms of corruption in Uganda. Using a survey of 12,000 citizens and 670 public officials, we found that citizens and public officials were slightly different in their perception of corruption, but corruption is a collaborative endeavor involving many behaviors that are discussed in detail. Key recommendations are to adopt technological inter-faces, reduce work incentives, and subject potential candidates to prove suitability before working in public service. Future research agendas are also discussed

Direct Use of Low Enthalpy Deep Geothermal Resources in the East African Rift Valley

Geothermal energy is already harnessed across East Africa to provide hundreds of megawatts of electricity, with significant plans for future expansion towards generation at the gigawatt scale. This power generation utilizes the high steam temperatures (typically more than 200 °C) that are available in several locations in Kenya, Ethiopia and elsewhere. The presence of these high enthalpy resources has deflected attention from the often attractive low and medium enthalpy resources present across a more extensive portion of the region. Geothermally heated water at cooler temperatures (less than 90 °C) could be widely produced by drilling shallower and cheaper boreholes than those required for power production. This low enthalpy resource could be widely exploitable throughout the Rift Valley, offering a low carbon, sustainable, reliable and commercially competitive source of heating, drying and cooling (via absorption chillers) to local farmers and growers, and for low temperature commercial and industrial uses. Applications of this type would displace expensive fossil fuels, reducing costs and carbon emissions as well as improving the region’s energy and food security. The power input for pump systems can be accommodated by relatively small generators, so direct heat projects could be beneficial to consumers in areas with no grid access

Characterizing energy flow in kelp forest food webs: a geochemical review and call for additional research

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Elliott Smith, E. A., & Fox, M. D. Characterizing energy flow in kelp forest food webs: a geochemical review and call for additional research. Ecography. 2021,https://doi.org/10.1111/ecog.05566.Kelp forests are highly productive coastal habitats that serve as biodiversity hotspots and provide valuable ecosystem services. Despite being one the largest marine biomes, kelp forests have been drastically understudied relative to other marine systems. Notably, while the role of kelp as habitat-forming, or ‘foundation species', is well-documented, a comprehensive understanding of kelp forest food web structure is lacking, particularly regarding the importance of kelp-derived energy/nutrients to consumers. Here, we provide a biogeographic perspective on the energetic underpinning of kelp forests based on published literature. We targeted studies which used geochemical proxies – stable isotope analysis – to examine the transfer of carbon from kelp to local consumers. These studies (n = 94) were geographically skewed, with > 40% from Northern European Seas and Temperate Northeast Pacific. Quantitative estimates for the percentage of kelp energy (or kelp + macroalgae if sources were pooled) incorporated by local consumers came from 43 publications, which studied 141 species and 35 broader taxonomic groups. We examined these data for trends among functional groups and across upwelling regimes. No patterns are evident at present, perhaps due to the paucity or variability of available data. However, energetic subsides from kelps clearly support a wide range of diverse taxa around the globe. We also characterized biogeographic patterns in δ13C values of kelps and particulate organic matter (POM, a phytoplankton proxy), to evaluate potential limitations of stable isotope analysis in disentangling the relative contributions of pelagic versus benthic resources to coastal food webs. Globally, kelps and POM differed by > 4.5‰, but there was substantial variation among regions and kelp species. Accordingly, we discuss advances in stable isotope techniques which are facilitating more precise analysis of these complex energetic pathways. We end by proposing four main avenues of critical future research that will shed light on the resilience of these communities to global change.This material is based upon work supported by the National Science Foundation under Grant no. (NSF 1907163) issued to EES. MF was supported by a Woods Hole Oceanographic Institution Postdoctoral Scholarship

Modeling Menstrual Cycle Length and Variability at the Approach of Menopause Using Bayesian Changepoint Models

As women approach menopause, the patterns of their menstruation cycle lengths change. To study these changes, we need to jointly model both the mean and variability of the cycle length. The model incorporates separate mean and variance change points for each woman and a hierarchical model to link them together, along with regression components to include predictors of menopausal onset such as age at menarche and parity. Data are from TREMIN, an ongoing 70-year old longitudinal study that has obtained menstrual calendar data of women throughout their reproductive life course. An additional complexity arises from the fact that these calendars have substantial missingness due to hormone use, surgery, failure to report, and loss of contact. We integrate multiple imputation and time-to event modeling in our Bayesian estimation procedure to deal with different forms of the missingness. Posterior predictive model checks are applied to evaluate the model fit. Our method successfully modeled patterns of women’s menstrual cycle trajectories throughout their late reproductive life and identified the change points for mean and variability of segment length, which provides insight into the menopausal process. More generally, our model points the way toward increasing use of joint mean-variance models to predict health outcomes and better understand disease processes

First principles mechanistic study of self-limiting oxidative adsorption of remote oxygen plasma during the atomic layer deposition of alumina

Plasma-enhanced atomic layer deposition (ALD) of metal oxides is a rapidly gaining interest especially in the electronics industry because of its numerous advantages over the thermal process. However, the underlying reaction mechanism is not sufficiently understood, particularly regarding saturation of the reaction and densification of the film. In this work, we employ first principles density functional theory (DFT) to determine the predominant reaction pathways, surface intermediates and by-products formed when constituents of O₂-plasma or O₃ adsorb onto a methylated surface typical of TMA-based alumina ALD. The main outcomes are that a wide variety of barrierless and highly exothermic reactions can take place. This leads to the spontaneous production of various by-products with low desorption energies and also of surface intermediates from the incomplete combustion of –CH₃ ligands. Surface hydroxyl groups are the most frequently observed intermediate and are formed as a consequence of the conservation of atoms and charge when methyl ligands are initially oxidized (rather than from subsequent re-adsorption of molecular water). Anionic intermediates such as formates are also commonly observed at the surface in the simulations. Formaldehyde, CH₂O, is the most frequently observed gaseous by-product. Desorption of this by-product leads to saturation of the redox reaction at the level of two singlet oxygen atoms per CH₃ group, where the oxidation state of C is zero, rather than further reaction with oxygen to higher oxidation states. We conclude that the self-limiting chemistry that defines ALD comes about in this case through the desorption by-products with partially-oxidised carbon. The simulations also show that densification occurs when ligands are removed or oxidised to intermediates, indicating that there may be an inverse relationship between Al/O coordination numbers in the final film and the concentration of chemically-bound ligands or intermediate fragments covering the surface during each ALD pulse. Therefore reactions that generate a bare surface Al will produce denser films in metal oxide ALD

The role of exercise in atrial fibrillation prevention and promotion: Finding optimal ranges for health

The cardiovascular benefits of regular exercise have been well described, including a significant reduction in cardiovascular morbidity and mortality for those meeting recommended guidelines. Yet the impact of physical activity on the incidence of atrial fibrillation (AF) has been less clear. This review seeks to define the optimal dose and duration for the prevention and treatment of AF. In doing so, we review the evidence that supports a decline in AF risk for those who achieve a weekly physical activity dose slightly above the current recommended guidelines. Furthermore, we identify the reduced AF incidence in those individuals who attain a cardiorespiratory fitness of 8 METs (metabolic equivalents of task) or more during maximal exercise testing. Finally, we review the evidence that shows an excess of AF among regular participants of endurance exercise

Self-Limiting Temperature Window for Thermal Atomic Layer Etching of HfO2 and ZrO2 Based on the Atomic-Scale Mechanism

HfO2 and ZrO2 are two high-k materials that are important in the downscaling of semiconductor devices. Atomic-level control of material processing is required for the fabrication of thin films of these materials at nanoscale device sizes. Thermal atomic layer etching (ALE) of metal oxides, in which up to one monolayer of the material can be removed, can be achieved by sequential self-limiting (SL) fluorination and ligand-exchange reactions at elevated temperatures. However, to date, a detailed atomistic understanding of the mechanism of thermal ALE of these technologically important oxides is lacking. In this paper, we investigate the hydrogen fluoride (HF) pulse in the first step in the thermal ALE process of HfO2 and ZrO2 using first-principles simulations. We introduce Natarajan–Elliott analysis, a thermodynamic methodology, to compare reaction models representing the self-limiting (SL) and continuous spontaneous etching (SE) processes taking place during an ALE pulse. Applying this method to the first HF pulse on HfO2 and ZrO2, we found that thermodynamic barriers impeding continuous etching are present at ALE-relevant temperatures. We performed explicit HF adsorption calculations on the oxide surfaces to understand the mechanistic details of the HF pulse. A HF molecule adsorbs dissociatively on both oxides by forming metal–F and O–H bonds. HF coverages ranging from 1.0 ± 0.3 to 17.0 ± 0.3 HF/nm2 are investigated, and a mixture of molecularly and dissociatively adsorbed HF molecules is present at higher coverages. Theoretical etch rates of −0.61 ± 0.02 Å/cycle for HfO2 and −0.57 ± 0.02 Å/cycle for ZrO2 were calculated using maximum coverages of 7.0 ± 0.3 and 6.5 ± 0.3 M–F bonds/nm2, respectively (M = Hf, Zr