Statistical Downscaling Methods for Climate Change Impact Assessment on Urban Rainfall Extremes for Cities in Tropical Developing Countries – a Review

International Conference on Flood Resilience: Experiences in Asia and Europe, Exeter, UK, 5-7 September 2013Results of most global and regional climate model simulations cannot be directly applied in future change impacts and adaptation studies of urban drainage and flood risk management. A form of downscaling is required to increase the spatial and temporal resolution of the modelled rainfall data. This paper provides a critical review of the current state of the art statistical downscaling techniques that can be applied to quantify climate change impacts on urban rainfall extremes. Emphasis is placed on delta change methods and Poisson cluster stochastic rainfall models. The paper discusses the applicability and key limitations of statistical downscaling in climate impact and adaptation studies for cities in tropical developing countries. From the review, it can be concluded that simpler statistical downscaling techniques with modest resource requirements such as climate impact sensitivity analyses, use of simple Markov chain or semi-empirical models, construction of climate analogues and spatial interpolation of grid point data are appropriate for scoping of climate impacts and evaluation of mitigation and adaptation strategies at the city scale. Emerging resilience based approaches that combine both scenario based climate model projections and acceptability thresholds defined by key flood risk management stakeholders are promising for application in climate impact and adaptation studies for cities in tropical developing countries.UK Commonwealth Scholarship Commission - PhD scholarshi

A global analysis approach for investigating structural resilience in urban drainage systems

Copyright © 2015 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Water Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Water Research (2015), DOI: 10.1016/j.watres.2015.05.030Building resilience in urban drainage systems requires consideration of a wide range of threats that contribute to urban flooding. Existing hydraulic reliability based approaches have focused on quantifying functional failure caused by extreme rainfall or increase in dry weather flows that lead to hydraulic overloading of the system. Such approaches however, do not fully explore the full system failure scenario space due to exclusion of crucial threats such as equipment malfunction, pipe collapse and blockage that can also lead to urban flooding. In this research, a new analytical approach based on global resilience analysis is investigated and applied to systematically evaluate the performance of an urban drainage system when subjected to a wide range of structural failure scenarios resulting from random cumulative link failure. Link failure envelopes, which represent the resulting loss of system functionality (impacts) are determined by computing the upper and lower limits of the simulation results for total flood volume (failure magnitude) and average flood duration (failure duration) at each link failure level. A new resilience index that combines the failure magnitude and duration into a single metric is applied to quantify system residual functionality at each considered link failure level. With this approach, resilience has been tested and characterized for an existing urban drainage system in Kampala city, Uganda. In addition, the effectiveness of potential adaptation strategies in enhancing its resilience to cumulative link failure has been tested.UK Commonwealth PhD scholarshipEngineering & Physical Sciences Research Council (ESPRC) - Safe & SuRe research fellowshi

Quantifying the Resilience of Urban Drainage Systems Using a Hydraulic Performance Assessment Approach

Copyright © Copyright 2014 13th International Conference on Urban Drainage 2014. All Rights Reserved.13th International Conference on Urban Drainage, Sarawak, Malaysian Borneo, 7-12 September 2014Although considerable progress has been made towards achieving sustainable urban water management, urban drainage systems (UDSs) are increasingly threatened by multiple and uncertain drivers of future change. Building the resilience of UDSs to flooding is increasingly recognised as an imperative to promoting the long term sustainability of the urban areas they serve. This paper describes a methodology that combines the use of hydraulic performance assessment with utility performance functions to quantify the resilience of UDSs during flooding (exceedance) conditions. Utility performance functions, which relate the overall UDS performance to flood depths, are derived from existing flood depth-damage data for UK residential properties for various rainfall return periods and are used to estimate UDS residual functionality and hence resilience to pluvial flooding. The study shows that by introducing a storage tank for flow attenuation, the duration of nodal flooding and the flooded volume can be reduced by 6 to 10% and 18 to 38%, respectively and the overall system resilience to flooding can be increased by 8.0 to 9.5%.UK Department for International Development (DFID) - Commonwealth PhD scholarship awardEPSRC (Engineering and Physical Sciences Research Council) Safe & SuRe Project fellowshi

Effects of fuel alcohols on BTEX plume dynamics: An assessment of natural attenuation using RT3D with a general substrate interaction module

A numerical model was developed to evaluate the effect of fuel alcohols present in reformulated gasoline on BTEX natural attenuation and groundwater plume elongation. The model, developed as a module for the RT3D (Reactive Transport in 3-Dimensions) model, includes commonly considered fate and transport processes (advection, dispersion, adsorption, biodegradation and depletion of electron acceptors during biodegradation) and substrate interactions previously not considered (e.g., a decrease in the specific benzene utilization rate due to metabolic flux dilution and/or catabolite repression) as well as microbial populations shifts, cosolvency effects, alcohol toxicity and source zone depletion dynamics that affect groundwater concentrations of gasoline constituents. The model was used to (1) evaluate the relative importance of benzene plume-elongation mechanisms, (2) how the concentration of ethanol in reformulated gasoline affects the length and longevity of benzene plumes, and (3) the effects of five fuel alcohols (methanol, ethanol, 1-propanol, iso-butanol and n-butanol) on the natural attenuation of benzene in fuel contaminated groundwater. Model simulations showed that all fuel alcohols can hinder the natural attenuation of benzene, due mainly to accelerated depletion of dissolved oxygen during their biodegradation (leading to strongly anaerobic methanogenic conditions) and a decrease in the specific degradation rate for benzene (due to catabolite repression and metabolic flux dilution). Thus, releases of alcohol-blended gasoline should result in longer benzene plumes compared to regular gasoline. However, the simulated lifespan of benzene plumes was shorter for blends with higher alcohol contents, due to a lower mass of benzene released, and increased microbial activity associated with fortuitous growth of BTEX degraders on fuel alcohols. Benzene plume elongation and longevity were more pronounced in the presence of alcohols that biodegrade slower (e.g., propanol and n-butanol), forming longer and more persistent alcohol plumes. In general, our model indicates that higher alcohols blends have a lower impact on BTEX natural attenuation, while more recalcitrant alcohols have a higher impact. Thus, E85 (85% Ethanol) had the lowest impact on BTEX plume elongation and B10 (10% n-Butanol) had the highest impact. However, simulations were highly sensitive to site-specific biokinetic coefficients for alcohol degradation, which forewarns against generalizations about the level of impact of specific fuel alcohols on benzene plume dynamics, and calls for further pilot-scale and field research to validate the assumptions and results from this model

Analytical model for BTEX natural attenuation in the presence of fuel ethanol and its anaerobic metabolite acetate

Copyright © 2013 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Contaminant Hydrology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Contaminant Hydrology Vol. 146 (2013), DOI: 10.1016/j.jconhyd.2012.12.006Flow-through column studies were conducted to mimic the natural attenuation of ethanol and BTEX mixtures, and to consider potential inhibitory effects of ethanol and its anaerobic metabolite acetate on BTEX biodegradation. Results were analyzed using a one-dimensional analytical model that was developed using consecutive reaction differential equations based on first-order kinetics. Decrease in pH due to acetogenesis was also modeled, using charge balance equations under CaCO3 dissolution conditions. Delay in BTEX removal was observed and simulated in the presence of ethanol and acetate. Acetate was the major volatile fatty acid intermediate produced during anaerobic ethanol biodegradation (accounting for about 58% of the volatile fatty acid mass) as suggested by the model data fit. Acetate accumulation (up to 1.1 g/L) near the source zone contributed to a pH decrease by almost one unit. The anaerobic degradation of ethanol (2 g/L influent concentration) at the source zone produced methane at concentrations exceeding its solubility (≅ 26 mg/L). Overall, this simple analytical model adequately described ethanol degradation, acetate accumulation and methane production patterns, suggesting that it could be used as a screening tool to simulate lag times in BTEX biodegradation, changes in groundwater pH and methane generation following ethanol-blended fuel releases

Development and Maintenance of the Brain’s Immune Toolkit: Microglia and Non-Parenchymal Brain Macrophages

Microglia and non-parenchymal macrophages located in the perivascular space, the meninges and the choroid plexus are independent immune populations that play vital roles in brain development, homeostasis, and tissue healing. Resident macrophages account for a significant proportion of cells in the brain and their density remains stable throughout the lifespan thanks to constant turnover. Microglia develop from yolk sac progenitors, later evolving through intermediate progenitors in a fine-tuned process in which intrinsic factors and external stimuli combine to progressively sculpt their cell type-specific transcriptional profiles. Recent evidence demonstrates that non-parenchymal macrophages are also generated during early embryonic development. In recent years, the development of powerful fate mapping approaches combined with novel genomic and transcriptomic methodologies have greatly expanded our understanding of how brain macrophages develop and acquire specialized functions, and how cell population dynamics are regulated. Here, we review the transcription factors, epigenetic remodeling, and signaling pathways orchestrating the embryonic development of microglia and non-parenchymal macrophages. Next, we describe the dynamics of the macrophage populations of the brain and discuss the role of progenitor cells, to gain a better understanding of their functions in the healthy and diseased brain. (c) 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 561-579, 2018Spanish Ministry of Economy and Competitiveness (MINECO) with European Regional Development Fund (ERDF) funds; contract grant numbers: BFU201566689, RYC-2013-12817. BBVA Foundation and a Basque Government; contract grant number: PI_2016_1_0011. "Ramon y Cajal" and European Social Fund (ESF) and national resources (MINEICO-AEI); contract grant number: RYC-2015-18056. MINECO co-financed by the European Regional Development Fund (ERDF); contract grant number: SAF2014-60233-JIN. Instituto de Neurociencias is a "Centre of Excellence Severo Ochoa"; contract grant number: SEV-2013-0317. Medical Research Council, Alzheimer's Research UK and The Leverhulme Trust

Bacterial fecal microbiota is only minimally affected by a standardized weight loss plan in obese cats

Background: Research in humans and mice suggests that obesity influences the abundance and diversity of gastrointestinal (GI) microbiota, and that an "obese microbiome" influences energy metabolism and fat storage in the host. Microbiota membership and composition have been previously assessed in healthy cats. However, research investigating the effects of obesity and weight loss on the cat's fecal microbiota is limited. Therefore, this study's objective was to evaluate differences in fecal microbial abundance and biodiversity, as well as serum cobalamin and folate concentrations in obese cats, before and after weight loss, and compare to lean cats. Fourteen lean and 17 obese healthy client-owned cats were fed a veterinary therapeutic weight loss food at maintenance energy requirement for 4 weeks. At the end of week 4, lean cats finished the study, whereas obese cats continued with a 10-week weight loss period on the same food, fed at individually-tailored weight loss energy requirements. Body weight and body condition score were recorded every 2 weeks throughout the study. At the end of each period, a fecal sample and food-consumption records were obtained from the owners, and serum cobalamin and folate concentrations were analysed. DNA was extracted from fecal samples, polymerase chain reaction (PCR) was performed, and products were sequenced using next-generation sequencing (Illumina MiSeq). Results: No significant differences in the relative abundance of taxa and in biodiversity indices were observed between cats in either group (P > 0.05 for all tests). Nevertheless, some significantly enriched taxa, mainly belonging to Firmicutes, were noted in linear discriminant analysis effect size test in obese cats before weight loss compared to lean cats. Serum cobalamin concentrations were significantly higher in lean compared to obese cats both before and after weight loss. Serum folate concentrations were higher in obese cats before weight loss compared to after. Conclusions: The association between feline obesity and the fecal bacterial microbiota was demonstrated in enriched taxa in obese cats compared to lean cats, which may be related to enhanced efficiency of energy-harvesting. However, in obese cats, the fecal microbial abundance and biodiversity were only minimally affected during the early phase of a standardized weight loss plan

Nitrate addition to groundwater impacted by ethanol-blended fuel accelerates ethanol removal and mitigates the associated metabolic flux dilution and inhibition of BTEX biodegradation

A comparison of two controlled ethanol-blended fuel releases under monitored natural attenuation (MNA) versus nitrate biostimulation (NB) illustrates the potential benefits of augmenting the electron acceptor pool with nitrate to accelerate ethanol removal and thus mitigate its inhibitory effects on BTEX biodegradation. Groundwater concentrations of ethanol and BTEX were measured 2 m downgradient of the source zones. In both field experiments, initial source-zone BTEX concentrations represented less than 5% of the dissolved total organic carbon (TOC) associated with the release, and measurable BTEX degradation occurred only after the ethanol fraction in the multicomponent substrate mixture decreased sharply. However, ethanol removal was faster in the nitrate amended plot (1.4 years) than under natural attenuation conditions (3.0 years), which led to faster BTEX degradation. This reflects, in part, that an abundant substrate (ethanol) can dilute the metabolic flux of target pollutants (BTEX) whose biodegradation rate eventually increases with its relative abundance after ethanol is preferentially consumed. The fate and transport of ethanol and benzene were accurately simulated in both releases using RT3D with our general substrate interaction module (GSIM) that considers metabolic flux dilution. Since source zone benzene concentrations are relatively low compared to those of ethanol (or its degradation byproduct, acetate), our simulations imply that the initial focus of cleanup efforts (after free-product recovery) should be to stimulate the degradation of ethanol (e.g., by nitrate addition) to decrease its fraction in the mixture and speed up BTEX biodegradation.Petróleo Brasileiro S/A — PETROBRASCoordination of Improvement of Higher Education Personnel (CAPES)National Council for Scientific and Technological Development (CNPq

Modeling benzene plume elongation mechanisms exerted by ethanol using RT3D with a general substrate interaction module

Copyright © 2008 American Geophysical Union (AGU)A mathematical model was developed to evaluate the effect of the common fuel additive ethanol on benzene fate and transport in fuel-contaminated groundwater and to discern the most influential benzene plume elongation mechanisms. The model, developed as a module for the Reactive Transport in 3 Dimensions (RT3D) model, includes commonly considered fate and transport processes (advection, dispersion, adsorption, biodegradation, and depletion of molecular oxygen during biodegradation) and substrate interactions previously not considered (e.g., a decrease in the specific benzene utilization rate due to metabolic flux dilution and/or catabolite repression) as well as microbial population shifts. Benzene plume elongation predictions, based on literature model parameters, were on the order of 40% for a constant source of E10 gasoline (10% vol/vol ethanol), which compares favorably to field observations. For low benzene concentrations (<1 mg/L), oxygen depletion during ethanol degradation was the principal mechanism hindering benzene natural attenuation. For higher benzene concentrations (exerting an oxygen demand higher than the available dissolved oxygen), metabolic flux dilution was the dominant plume elongation process. If oxygen were not limiting, as might be the case in zones undergoing aerobic biostimulation, model simulations showed that microbial growth on ethanol could offset negative substrate interactions and enhance benzene degradation, resulting in shorter plumes than baseline conditions without ethanol

Diagnostic approaches, aetiological agents and their associations with short-term survival and laminitis in horses with acute diarrhoea admitted to referral institutions

Background: An international description of the diagnostic approaches used in different institutions to diagnose acute equine diarrhoea and the pathogens detected is lacking. Objectives: To describe the diagnostic approach, aetiological agents, outcome, and development of laminitis for diarrhoeic horses worldwide. Study design: Multicentre retrospective case series. Methods: Information from horses with acute diarrhoea presenting to participating institutions between 2016 and 2020, including diagnostic approaches, pathogens detected and their associations with outcomes, were compared between institutions or geographic regions. Results: One thousand four hundred and thirty‐eight horses from 26 participating institutions from 4 continents were included. Overall, aetiological testing was limited (44% for Salmonella spp., 42% for Neorickettsia risticii [only North America], 40% for Clostridiodes difficile, and 29% for ECoV); however, 13% (81/633) of horses tested positive for Salmonella, 13% (35/262) for N. risticii, 9% (37/422) for ECoV, and 5% (27/578) for C. difficile. C. difficile positive cases had greater odds of non‐survival than horses negative for C. difficile (OR: 2.69, 95%CI: 1.23–5.91). In addition, horses that were positive for N. risticii had greater odds of developing laminitis than negative horses (OR: 2.76, 95%CI: 1.12–6.81; p = 0.029). Main limitations: Due to the study's retrospective nature, there are missing data. Conclusions: This study highlighted limited diagnostic investigations in cases of acute equine diarrhoea. Detection rates of pathogens are similar to previous reports. Non‐survival and development of laminitis are related to certain detected pathogens