Simona M Hapca

• PhD
• Lecture in Statistics at University of Stirling

Background Diabetic retinopathy (DR) is a major sight-threatening microvascular complication in individuals with diabetes. Systemic inflammation combined with oxidative stress is thought to capture most of the complexities involved in the pathology of diabetic retinopathy. A high level of neutrophil–lymphocyte ratio (NLR) is an indicator of abnorma...

Our aim was to investigate the association of glycated haemoglobin A1c (HbA1c) variability score (HVS) with estimated glomerular filtration rate (eGFR) slope in Chinese adults living with type 2 diabetes. This cohort study included adults with type 2 diabetes attending outpatient clinics between 2011 and 2019 from a large electronic medical record-...

Background Cognitive impairment is common in older people admitted to hospital, but previous research has focused on single conditions. Objective This project sits in phase 0/1 of the Medical Research Council Framework for the Development and Evaluation of Complex Interventions. It aims to develop an understanding of current health-care outcomes....

Background and Aims Quinine can precipitate Acute Kidney Injury (AKI) by immune-mediated reactions. Cramps, for which quinine is traditionally prescribed, may be a symptom of conditions that are risk factors for AKI. The relationship between quinine and AKI at a population level is unclear. The aim of this study was to establish and quantify any ob...

Objectives: to establish and quantify any observable association between the exposure to community prescriptions for quinine and acute kidney injury (AKI) events in a population of older adults. Design: two observational studies using the same dataset, a retrospective longitudinal cohort study and a self-controlled case series (SCCS). Setting:...

Background: Type-2 diabetes (T2D) patients have a substantially higher risk of cardiovascular disease (CVD) and disproportionately affected by ethnicity such as Asian and Caucasian. HDL cholesterol (HDL-C) remains a better biochemical predictor of CVD risk, but South Indians are defined by lower HDL-c level. Objective: To study the differences in...

Aims: Metformin uptake is transporter-dependent. Observational data indicates that reduced-function variants in organic cation transporter 1 (OCT1) and OCT1-inhibiting drugs increase risk of metformin intolerance. The ImpOCT study investigated impact of OCT1 genotype and use of omeprazole (an OCT1-inhibiting drug) on an individual’s metformin toler...

To address a number of issues of great societal concern at the moment, like the sequestration of carbon, information is direly needed about interactions between soil architecture and microbial dynamics. Unfortunately, soils are extremely complex, heterogeneous systems comprising highly variable and dynamic micro-habitats that have significant impac...

To address a number of issues of great societal concern at the moment, like the sequestration of carbon, information is direly needed about interactions between soil architecture and microbial dynamics. Unfortunately, soils are extremely complex, heterogeneous systems comprising highly variable and dynamic micro-habitats that have significant impac...

Background Cognitive spectrum disorders (CSDs) are common in hospitalised older adults and associated with adverse outcomes. Their association with the maintenance of independent living has not been established. The aim was to establish the role of CSDs on the likelihood of living at home 30 days after discharge or being newly admitted to a care ho...

Mosquito breeding sites were grouped into two different study zones (A and B) on the basis of human related activities taking place in and around the breeding sites. An. gambiae larvae collected from ecologically contrasting breeding sites were reared to adults in the laboratory. Adults from the F1 progeny were assayed for resistance against 4% DDT...

Purpose Cognitive impairment is common in older people admitted to hospital, but the outcomes are generally poorly understood, and previous research has shown inconsistent associations with mortality depending on the type of cognitive impairment examined and duration of follow-up. This study examines mortality in older people with any cognitive imp...

Background: Retinopathy is a frequent microvascular complication in diabetic individuals in the productive age group. Development and progression of retinopathy varies between individuals. The reason for this variability is not clear and requires further research. Vascular endothelial growth factor (VEGF) is a mitogen that causes increased vascular...

Title: Data driven cluster analysis of type 2 diabetes data from Tayside and Fife, Scotland. Background: Type 2 Diabetes is a complex heterogenous disease condition. Sub-classification of diabetes based on the variables at diagnosis may aid in developing early intensification of treatment for specific group of individuals. Methods: We analysed rece...

Background: Statins mainly act on the reduction of low-density lipoprotein-cholesterol (LDL-C) levels. Statin therapy also helps in improving high-density lipoprotein-cholesterol (HDL-C) levels up to 10-15%. However, Inter-individual variation in HDL-c response to statins therapy could be partially explained by genetic variation. The main Objectiv...

Over the last 60 years, soil microbiologists have accumulated a wealth of experimental data showing that the bulk, macroscopic parameters (e.g., granulometry, pH, soil organic matter, and biomass contents) commonly used to characterize soils provide insufficient information to describe quantitatively the activity of soil microorganisms and some of...

Aims To test the effectiveness of a theoretically based text‐message intervention to reduce binge drinking among socially disadvantaged men. Design A multi‐centre parallel group, pragmatic, individually randomized controlled trial. Setting Community‐based study conducted in four regions of Scotland. Participants A total of 825 men aged 25–44 yea...

Vector resistance to insecticides is a major challenge in the crusade towards effective malaria control. The issue of tolerance of An. gambiae to commonly used insecticides that were hitherto active against the An. gambiae population has necessitate further effort towards recognizing the biological factors in the insects that facilitates the resist...

Glutathione (GSH) is widely distributed among all living organisms and associated with diverse functions that include maintaining redox homeostasis and detoxification of xenobiotic compounds. The level of GSH within the cell varies with stress often involving changes in GSH content, which is consumed in reactions that protect the cell leading to fo...

Bacterial bio-surfactants have a wide range of biological functions and biotechnological applications. Previous analyses had suggested a limit to their reduction of aqueous liquid surface tensions (γMin), and here we confirm this in an analysis of 25 Pseudomonas spp. strains isolated from soil which produce high-strength surfactants that reduce sur...

This study was carried out in 2015 to assess the level of resistance of sibling species of Anopheles gambiae complex the principal malaria vector from Bichi in Kano state to three classes of insecticides; (DDT, Permethrin and Bendiocarb) approved by World Health Organization (WHO) for vector control with the aim of obtaining baseline susceptibility...

The pore size distribution (PSD) of the void space is widely used to predict a range of processes in soils. Recent advances in X-ray computed tomography (CT) now afford novel ways to obtain exact data on pore geometry, which has stimulated the development of algorithms to estimate the pore size distribution from 3D data sets. To date there is howev...

Background: Cognitive impairment of various kinds is common in older people admitted to hospital, but previous research has usually focused on single conditions in highly-selected groups and has rarely examined associations with outcomes. This study examined prevalence and outcomes of cognitive impairment in a large unselected cohort of people age...

In this work, experimental and modelling investigations were conducted on biochars pyrolyzed at 350 °C and 600 °C, to determine the effect of pyrolysis temperature, hydrogen peroxide activation and pH on copper and zinc removal, in comparison with commercially available activated carbons. Characterization of biochars was performed by BET surface ar...

Although bacterial cellulose synthase (bcs) operons are widespread within the Proteobacteria phylum, subunits required for the partial-acetylation of the polymer appear to be restricted to a few γ-group soil, plant-associated and phytopathogenic pseudomonads, including Pseudomonas fluorescens SBW25 and several Pseudomonas syringae pathovars. Howeve...

Biosurfactants which reduce the surface or interfacial tension of liquids and act as emulsifiers, foaming and dispersing agents with low toxicity, are increasingly finding applications in biotechnology and driving the search for novel compounds for further exploitation. Potential biosurfactants sourced from bacteria are often selected first by qual...

Background and Aims Biochar amendment to soil is a promising practice of enhancing productivity of agricultural systems. The positive effects on crop are often attributed to a promotion of beneficial soil microorganisms while suppressing pathogens e.g. This study aims to determine the influence of biochar feedstock on (i) spontaneous and fungi inoc...

Malaria being the most important endemic protozoan disease in the tropics in terms of morbidity and mortality has attracted a continuous effort by researchers for it's control and prevention. Malaria vector control programs in Africa rely heavily on the use of pesticides for insecticide treated nets (ITN) and long lasting insecticides treated nets...

There is currently a significant need to improve our understanding of the factors that control a number of critical soil processes by integrating physical, chemical and biological measurements on soils at microscopic scales to help produce 3D maps of the related properties. Because of technological limitations, most chemical and biological measurem...

Anopheles gambiae (An. gambiae) is the principal malaria vector in Africa, where vector control measures involve the use of insecticides. The development of insecticides resistance mitigates these approaches. Glutathione (GSH) is widely distributed among all living organisms and is associated with detoxification pathways, especially the Glutathione...

This study underpins quantitative relationships that account for the combined effects that starting biomass and peak pyrolysis temperature have on physico-chemical properties of biochar. Meta-data was assembled from published data of diverse biochar samples (n=102) to (i) obtain networks of intercorrelated properties and (ii) derive models that pre...

Experimental evolution studies are used to investigate bacterial adaptive radiation in simple microcosms. In the case of the Wrinkly Spreader, a class of biofilm-forming adaptive mutants of Pseudomonas fluorescens SBW25, the current paradigm is that they are only evolutionarily successful in static microcosms where they out-compete other lineages f...

It is generally accepted that climate change is likely to disrupt host-parasite relationships, but little consideration has been given to how this may affect agricultural pests. Here, we study the potential influence of climate change on the pest slug Deroceras reticulatum and its nematode parasite Phasmarhabditis hermaphrodita. The European slug D...

Abstract Anopheles gambiae (An. gambiae) is the principal malaria vector in Africa, where vector control measures involve the use of insecticides. The development of insecticides resistance mitigates these approaches. Glutathione (GSH) is widely distributed among all living organisms, and is associated with detoxification pathways, especially the...

Unlabelled: Bacteria produce a variety of biosurfactants capable of significantly reducing liquid (aqueous) surface tension (γ) with a range of biological roles and biotechnological uses. To determine the lowest achievable surface tension (γMin ), we tested a diverse collection of Pseudomonas-like isolates from contaminated soil and activated slud...

X-ray microtomography, through quantification of soil structure at the microscale, could greatly facilitate the current understanding of soil hydrodynamic behaviour. However, binarisation method and processing choices are subjective and can have a strong impact on results and conclusions. In this study, we test a new method based on the porosity de...

Recent advances in imaging techniques offer the possibility of visualizing the three-dimensional structure of soils at very fine scales. To make use of such information, a thresholding process is commonly implemented to separate the image into solid particles and pores. Despite the multitude of thresholding algorithms available, their performance i...

The ability to colonise the surface of liquids has obvious advantages for bacteria and biofilm formation at the meniscus and air-liquid (A-L) interface is common amongst environmental pseudomonads. Bacteria from this genus also colonise raw meat and in this work the ability of these to produce biofilms was assessed. Sixty isolates were recovered fr...

A connectivity function defined by the 3D-Euler number, is a topological indicator and can be related to hydraulic properties (Vogel and Roth, 2001). This study aims to develop connectivity Euler indexes as indicators of the ability of soils for fluid percolation. The starting point was a 3D grey image acquired by X-ray computed tomography of a soi...

Recent 2-dimensional measurements reveal that soils are chemically very heterogeneous at nanometric and micrometric scales. Direct measurement techniques are still lacking to extend these observations to 3 dimensions. Sequential sectioning of soils, followed by 2-dimensional mapping of chemical elements and geometric interpolation to 3D, appears to...

Several biological roles have been demonstrated for surfactants expressed by soil and rhizosphere Pseudomonas spp., but the impact of these powerful surface-active agents on the local soil-water distribution within the partially saturated soil pore network has not been examined. To investigate this potential hydrological role, the liquid surface te...

Despite the importance of fungi in soil ecosystem services, a theoretical framework that links soil management strategies with fungal ecology is still lacking. One of the key challenges is to understand how the complex geometrical shape of pores in soil affects fungal spread and species interaction. Progress in this area has long been hampered by a...

Despite the importance of fungi in soil ecosystem services, a theoretical framework that links soil management strategies with fungal ecology is still lacking. One of the key challenges is understanding how the complex geometrical shape of pores in soil affects fungal spread and species interaction. Progress in this area has long been hampered by a...

The soil-dwelling nematodes Steinernema carpocapsae, S. scapterisci, S. feltiae, S. glaseri, Heterorhabditis bacteriophora, H. megidis, Phasmarhabditis hermaphrodita and Caenorhabditis elegans were placed on agar plates each containing four substrates (peat, sand, sandy loam and leaf litter). The body-waving behaviour of infective juveniles was rec...

Entomopathogenic nematodes (EPN) are soil-transmitted parasites and their foraging strategies are believed to range from 'ambush' to 'cruise' foragers. However, research on their behaviour has not considered the natural habitat of these nematodes. We hypothesized that EPN behaviour would be influenced by soil habitat quality and tested this hypothe...

The commercially available parasitic nematode Phasmarhabditis hermaphrodita is an effective biocontrol agent for slugs and particularly Deroceras reticulatum, a widespread pest species. Use of the nematode is currently limited by cost and it may be that by developing a fuller understanding of the ecology and behaviour of this nematode, more cost ef...

We consider multifractal analysis in time scale to analyse the effect of structural heterogeneity on the movement of the slug-parasitic nematode, Phasmarhabditis hermaphrodita. The study involves image recording and analysis of nematode movement on a homogeneous layer of technical agar compared to movement of nematodes in a structurally heterogeneo...

The characterization of the dispersal of populations of non-identical individuals is relevant to most ecological and epidemiological processes. In practice, the movement is quantified by observing relatively few individuals, and averaging to estimate the rate of dispersal of the population as a whole. Here, we show that this can lead to serious err...

We use a correlated random walk model in two dimensions to simulate the movement of the slug parasitic nematode Phasmarhabditis hermaphrodita in homogeneous environments. The model incorporates the observed statistical distributions of turning angle and speed derived from time-lapse studies of individual nematode trails. We identify strong temporal...

We consider the effect of structural heterogeneity on the movement of the slug-parasitic nematode, Phasmarhabditis hermaphrodita. The study involves image recording and analysis of nematode movement on a homogeneous layer of technical agar compared to movement of nematodes in a structurally heterogeneous environment that was created by adding sand...

Phasmarhabditis hermaphrodita is a parasitic nematode capable of killing several species of slugs including Deroceras reticulatum, the most widespread slug pest in the world. This nematode can control slug infestations in a wide range of crops such as wheat, lettuce and strawberries. Optimization of this biocontrol agent depends on a proper underst...

Global classical solutions to the viscous Hamilton-Jacobi equation u(t) - Delta u = a|del u|(p) in (0,infinity) x Omega with homogeneous Dirichlet boundary conditions are shown to converge to zero in W-1,W-infinity(Omega) at the same speed as the linear heat semigroup when p > 1. For p = 1, an exponential decay to zero is also obtained but the rate...

We prove the existence and the uniqueness of strong solutions for the viscous Hamilton-Jacobi Equation with Neumann boundary condition and initial data a continious function. Then, we study the large time behavior of the solutions.

We prove the existence and the uniqueness of strong solutions for the viscous Hamilton-Jacobi equation: ut - Δu = a ∇u p, t > 0, x ∈ Ω with Neumann boundary condition, and initial data μ0, a continuous function. The domain Ω is a bounded and convex open set with smooth boundary, a ∈ ℝ, a ≠ 0 and p > 0. Then, we study the large time behavior of the...

We study the weak solvability of viscous Hamilton-Jacobi equation: \(\partial_t u- \Delta u\,+\,|\nabla u|^p\,=\,0,t\,>\,0,\,x\,\in\,\Omega,\) with Neumann boundary condition and irregular initial data μ0. The domain \(\Omega\,\subset\,{\bold R}^{\bold N}\) is a bounded open set and p > 0. The last part deals with the case Ω a convex set and the in...

Cette thèse est consacrée à l'étude de l'équation de Hamilton-Jacobi avec viscosité (VHJ) sur des ouverts bornés à frontière régulière. Cette équation est un problème parabolique non-linéaire dont le second terme est une puissance du gradient de la solution. On étudie l'existence, l'unicité et la régularité des solutions faibles des problèmes aux l...

We prove an existence result for a class of Dirichlet boundary value problems with discontinuous nonlinearity and involving a Leray-Lions operator. The proof combines monotonicity methods for elliptic problems, variational inequality techniques and basic tools related to monotone operators. Our work generalizes a result obtained in Carl [4].

We study the existence, uniqueness, and regularity of weak solutions for a viscous Hamilton-Jacobi equation of the form: $u_t-\Delta u=a|\nabla u|^p, $ $p\in(0,\infty)$ and $a\in{{\bf R}}$, $a\neq 0$, with Dirichlet boundary condition and irregular initial data $\mu_0$. The cases of initial data $\mu_0$ a bounded Radon measure, or a function in th...