River dunes in unsteady conditions

This thesis explores the nature of river dunes in unsteady conditions. River dune research has two main philosophical approaches that are necessitated by the nature of dunes; they are individually dynamic features emergent from the interaction between flow and sediment transport, whilst this dynamism is restricted by a mixture of instantaneous and historical flow and sediment boundary conditions.This thesis has applied both philosophical approaches to the investigation of river dunes in unsteady conditions and highlights key areas where flow and sediment processes at the laboratory scale overlap that of the larger scale river, such as in the suspension of sediment, and importance of velocity profile shape on dune shape. Normalising the downstream velocity with shear velocity was repeatedly found to simplify and explain the fluid processes over dunes across a range of conditions and indicates that the dominant processes controlling dune shape and sediment mobility are hydraulically smooth, despite hydraulically rough grain sizes. The existence of a turbulent wave over dunes reduces the magnitude of flow velocity that reaches the bed and effectively changes the grain Reynolds number. This turbulent flow structure was extensively measured in this thesis, with detailed instantaneous flow velocity measurements, across a range of flow conditions over fixed bedforms with the use of Particle Imaging Velocimetry. This also revealed that the well-known equilibrium turbulent flow structure over dunes is dramatically altered when in transient flow-morphology conditions. It was found that the wake and stacked wake, changes location and intensity with flow depth and discharge, and that reattachment length is strongly related to U/u* as measured at the dune crest. This research provides descriptions of the causal mechanisms behind many bedform adaptions to flow unsteadiness, such as the formation of humpback dunes in high shear stress conditions.A second set of laboratory experiments explored the mean scaling of dunes with a mobile bed in a recirculating flume. The mean velocity profile shape was adjusted to move the point of maximum downstream velocity toward the bed, whilst keeping depth and depth averaged velocity- two variables used in almost all bedform stability diagrams, the same. It was found that dune height scaled with bed shear stress in a parabola, whilst dune wavelength scaled linearly. This indicates that dune height is primarily controlled via flow separation and dune wavelength scales most well is shear velocity and grain size (i.e. sediment transport lengths).Lastly, dunes were measured in the field during the falling leg of the monsoonal wet season floods on a section of the Mekong River in Cambodia. The river bed consisted of large dunes with superimposed bedforms. The geometry of the large dunes showed no relationship with the hydraulic conditions present; however the secondary dunes size responded to the variations in flow depth. All large dunes migrated at a constant rate, despite variation in height, and it was hypothesised that the superimposed bedforms provided any excess sediment for the host dune migration.Large dune height was half that predicted from empirical equations using flow depth. Variations in suspended sediment did not match those predicted via the Rouse number, instead, plotting U/u*, across variations in discharge and depth showed a good relationship with suspended sediment concentration. This relationship between flow structure and suspended sediment, with the concurrent variation secondary dune size indicated that the large dunes were depth limited. This is despite the consistent presence of secondary dunes at the crest of the host bedform or strong free surface interaction and suggests that dune height in rivers with superimposed bedforms is controlled by the existence of superimposed bedforms

The Use of Visible Light Absorbing Bismuth-Containing Semiconductors as Heterogeneous Photocatalysts for Selective Chemical Transformations

Bismuth-containing semiconducting materials were used as visible light absorbing heterogeneous photocatalysts for selective chemical transformations. The work demonstrates the importance of kinetic control in achieving selectivity; either through photocatalyst inhibition or through the presence of reagents capable of fast reactions with known intermediates. Bismuth oxide (β-Bi2O3), bismuth ferrite (BiFeO3), bismuth tungstate microflowers (Bi2WO6) and bismuth vanadate nanoparticles (nan-BiVO4) were synthesised and characterised by PXRD, SEM, DRUVS and BET. The bismuth-containing oxides were compared as photocatalysts for the aerobic oxidation of benzyl alcohol. The highest benzyl alcohol conversion (88%) and benzaldehyde selectivity (95%) was achieved with the use of nan-BiVO4. Further modifications to nan-BiVO4 resulted in materials that were less active for selective benzyl alcohol oxidation than unmodified nan-BiVO4. Further study of nan-BiVO4 as a heterogeneous photocatalysts for the selective oxidation of para-substituted benzyl alcohols was carried out. It was found that alcohol conversions and aldehyde selectivities were affected by by-product inhibition. The addition of 1 mol% 4-methoxybenzoic acid significantly reduced 4-methoxybenzyl alcohol conversion (to 49%). Isotopically labelled benzyl alcohols were used to show that α C-H bond cleavage was not rate limiting. However, changes in charge carrier lifetimes observed using TRPLS suggested that the charge carriers associated to the lifetimes observed were relevant to benzyl alcohol oxidation. Bismuth-containing semiconductors were also investigated as trifluoromethylation heterogeneous photocatalysts. Nan-BiVO4 was capable of oxytrifluoromethylation of styrene via the reduction of Umemoto’s reagents. The highly selective reaction produced the corresponding trifluoromethylated ketone in an 88% yield. Platinised bismuth tungstate (0.15-Pt-Bi2WO6) was found to give high conversions and product selectivities for the formation of Photo-Giese products (phenylacetic acid conversion = 99%, Photo-Giese product selectivity = 94%). Several coupling products were synthesised from different carboxylic acids and electron deficient alkenes. Competitive adsorption from by-products inhibition had an impact on acid conversions and Photo-Giese product selectivities

Executive functions in adults with developmental dyslexia

Background: Executive functioning (EF) deficits are well recognized in developmental dyslexia, yet the majority of studies have concerned children rather than adults, ignored the subjective experience of the individual with dyslexia (with regard to their own EFs), and have not followed current theoretical perspectives on EFs. Aims and Methods: The current study addressed these shortfalls by administering a self-report measure of EF (BRIEF-A; Roth, Isquith & Gioia, 2005) and experimental tasks to IQ-matched groups of adults with and without dyslexia. The laboratory-based tasks tested the three factors constituting the framework of EF proposed by Miyake et al. (2000). Results: In comparison to the group without dyslexia, the participants with dyslexia self-reported more frequent EF problems in day-to-day life, with these difficulties centering on metacognitive processes (working memory, planning, task monitoring, and organization) rather than on the regulation of emotion and behaviour. The participants with dyslexia showed significant deficits in EF (inhibition, set shifting, and working memory). Conclusions and Implications: The findings indicated that dyslexia-related problems have an impact on the daily experience of adults with the condition. Further, EF difficulties are present in adulthood across a range of laboratory-based measures, and, given the nature of the experimental tasks presented, extend beyond difficulties related solely to phonological processing

Sit still and pay attention: Using the Wii Balance-Board to detect lapses in concentration in children during psychophysical testing.

During psychophysical testing, a loss of concentration can cause observers to answer incorrectly, even when the stimulus is clearly perceptible. Such lapses limit the accuracy and speed of many psychophysical measurements. This study evaluates an automated technique for detecting lapses based on body movement (postural instability). Thirty-five children (8-11 years of age) and 34 adults performed a typical psychophysical task (orientation discrimination) while seated on a Wii Fit Balance Board: a gaming device that measures center of pressure (CoP). Incorrect responses on suprathreshold catch trials provided the "reference standard" measure of when lapses in concentration occurred. Children exhibited significantly greater variability in CoP on lapse trials, indicating that postural instability provides a feasible, real-time index of concentration. Limitations and potential applications of this method are discussed

Molecular pharmacodynamics of meropenem for nosocomial pneumonia caused by <i>Pseudomonas aeruginosa</i>.

ImportanceThe emergence of antimicrobial resistance (AMR) during antimicrobial treatment for hospital-acquired pneumonia (HAP) is a well-documented problem (particularly in pneumonia caused by Pseudomonas aeruginosa) that contributes to the wider global antimicrobial resistance crisis. During drug development, regimens are typically determined by their sufficiency to achieve bactericidal effect. Prevention of the emergence of resistance pharmacodynamics is usually not characterized or used to determine the regimen. The innovative experimental platform described here allows characterization of the emergence of AMR during the treatment of HAP and the development of strategies to mitigate this. We have demonstrated this specifically for meropenem-a broad-spectrum antibiotic commonly used to treat HAP. We have characterized the antimicrobial resistance pharmacodynamics of meropenem when used to treat HAP, caused by initially meropenem-susceptible P. aeruginosa, phenotypically and genotypically. We have also shown that intensifying the regimen and using combination therapy are both strategies that can both treat HAP and suppress the emergence of resistance

Pharmacodynamics of Meropenem and Tobramycin for Neonatal Meningoencephalitis: Novel Approaches to Facilitate the Development of New Agents to Address the Challenge of Antimicrobial Resistance

Neonatal sepsis is an underrecognized burden on health care systems throughout the world. Antimicrobial drug resistance (AMR) is increasingly prevalent and compromises the use of currently recommended first-line agents. The development of new antimicrobial agents for neonates and children is mandated by regulatory agencies. However, there remains uncertainty about suitable development pathways, especially because of the propensity of premature babies to develop meningoencephalitis as a complication of neonatal sepsis and difficulties studying this disease in clinical settings. We developed a new platform and approach to accelerate the development of antimicrobial agents for neonatal bacterial meningoencephalitis using Pseudomonas aeruginosa as the challenge organism. We defined the pharmacodynamics of meropenem and tobramycin in these models. The percentage of partitioning of meropenem and tobramycin into the cerebrospinal fluid was comparable at 14.3 and 13.7%, respectively. Despite this similarity, there were striking differences in their pharmacodynamics. Meropenem resulted in bactericidal activity in both the cerebrospinal fluid and cerebrum, whereas tobramycin had minimal antibacterial activity. A hollow fiber infection model (HFIM) using neonatal CSF concentration time profiles yielded pharmacodynamics comparable to those observed in the rabbit model. These new experimental models can be used to estimate the pharmacodynamics of currently licensed agents and those in development and their potential efficacy for neonatal bacterial meningoencephalitis

How Could Children’s Storybooks Promote Empathy? A Conceptual Framework Based on Developmental Psychology and Literary Theory

This conceptual paper proposes a framework for understanding the developmental mechanisms and literary characteristics that bind children’s storybooks with empathy. The article begins with a taxonomy of empathy composed of three key continuous dimensions: cognitive/emotional empathy, empathy for in-group and out-group members and empathy with positive and negative consequences. Insights from developmental psychology and literary theory form the basis for an interdisciplinary framework based on three premises: (1) book-reading can support empathy if it fosters in-group/out-group identification and minimizes in-group/out-group bias; (2) identification with characters who are dissimilar from the readers is the most valuable contribution of children’s storybooks to cognitive empathy; and (3) the quality of language positions children’s storybooks as an exceptional, but not exclusive, empathy-building form of fictional narratives. Implications for future intervention and empirical work are provided

Economic Evaluation and Transferability of Physical Activity Programmes in Primary Prevention: A Systematic Review

This systematic review aims to assess the characteristics of, and the clinical and economic evidence provided by, economic evaluations of primary preventive physical exercise interventions, and to analyse their transferability to Germany using recommended checklists. Fifteen economic evaluations from seven different countries met eligibility criteria, with seven of the fifteen providing high economic evidence in the special country context. Most of the identified studies conclude that the investigated intervention provide good value for money compared with alternatives. However, this review shows a high variability of the costing methods between the studies, which limits comparability, generalisability and transferability of the results

The human touch: Using a webcam to autonomously monitor compliance during visual field assessments

Purpose: To explore the feasibility of using various easy-to-obtain biomarkers to monitor non-compliance (measurement error) during visual field assessments. Methods: Forty-two healthy adults (42 eyes) and seven glaucoma patients (14 eyes) underwent two same-day visual field assessments. An ordinary webcam was used to compute seven potential biomarkers of task compliance, based primarily on eye gaze, head pose, and facial expression. We quantified the association between each biomarker and measurement error, as defined by (1) test–retest differences in overall test scores (mean sensitivity), and (2) failures to respond to visible stimuli on individual trials (stimuli −3 dB or more brighter than threshold). Results: In healthy eyes, three of the seven biomarkers were significantly associated with overall (test–retest) measurement error (P = 0.003–0.007), and at least two others exhibited possible trends (P = 0.052–0.060). The weighted linear sum of all seven biomarkers was associated with overall measurement error, in both healthy eyes (r = 0.51, P < 0.001) and patients (r = 0.65, P < 0.001). Five biomarkers were each associated with failures to respond to visible stimuli on individual trials (all P < 0.001). Conclusions: Inexpensive, autonomous measures of task compliance are associated with measurement error in visual field assessments, in terms of both the overall reliability of a test and failures to respond on particular trials (“lapses”). This could be helpful for identifying low-quality assessments and for improving assessment techniques (e.g., by discounting suspect responses or by automatically triggering comfort breaks or encouragement). Translational Relevance: This study explores a potential way of improving the reliability of visual field assessments, a crucial but notoriously unreliable clinical measure