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Experimental Evidence for the Secondary Transfer Effect: An Investigation of Direct and Vicarious Contact in the Laboratory
Get PDFPositive intergroup contact promotes positive outgroup attitudes (primary transfer effect; PTE), and these primary outgroup attitudes can generalise to other outgroups (the secondary transfer effect; STE). However, experimental evidence demonstrating the STE is rare. We collected data from 116 White South African female participants using a pretest‐posttest‐delayed‐posttest design with randomised allocation across three conditions (direct contact, vicarious contact, control), in the first simultaneous laboratory experimental test of the STE of both direct and vicarious contact. Participants in the vicarious contact condition observed another White South African female (an ingroup friend) in the direct contact condition completing a Relationship Closeness Induction Task with a female Black (African) South African (primary outgroup) confederate. We found: (1) a PTE for outgroup attitudes (but not trust) at immediate‐ and delayed‐posttest; (2) an STE (for attitudes, but not trust) at immediate‐ and delayed‐posttest: direct and vicarious contact with the primary outgroup improved attitudes towards Coloured South Africans (secondary outgroup) via changes in primary outgroup attitudes; and (3) an STE for a more demanding version of the STE, namely attitude‐to‐trust generalisation: changes in primary outgroup attitudes promoted changes in secondary outgroup trust at immediate‐ and delayed‐posttest. We discuss the contrasting results we observed for the generalisation of outgroup attitudes versus the generalisation of outgroup trust and offer suggestions for future research. These encouraging results should support future interventions designed to reduce prejudice across multiple outgroups
Mammalian herbivory indirectly shapes savanna arthropod communities but only at very low or high levels
Get PDFSavanna ecosystems support unique biodiversity and provide livelihoods for millions of people. Yet, wild herbivores are in decline due to poaching and land‐use change while livestock numbers are increasing. These changes in density and composition alter savanna vegetation. There are likely indirect cascading effects of altered vegetation on savanna arthropods, but our understanding is limited despite their pivotal role in ecosystem functioning. We evaluate how differences in mammalian herbivory affect terrestrial arthropods in a semiarid Kenyan savanna. We sampled ground‐active arthropods (focusing on ants) in six herbivory treatments ranging from high‐intensity herbivory to complete exclusion of large herbivores. Ant abundance and richness were not affected by herbivory treatments, but the community composition of ants and arthropods differed at extremely high and low levels of herbivory due to indirect impacts on vegetation. Community composition changes occurred under extremely high levels of herbivory because the resulting short‐grass communities and patches of bare ground led to high species turnover in ants. By contrast, extremely low herbivory promoted woody encroachment that led to the loss of savanna specialists via both species turnover and nestedness. We conclude that cascading effects of mammalian herbivory play only a relatively small role in shaping savanna arthropod communities, except at extreme levels of herbivory. However, the occurrence of savannas with these extreme levels of herbivory, both high and low, is likely to increase in the future, which may lead to more widespread changes in ecosystem functioning as a consequence of shifts in arthropod community composition
Laser writing of graphitic structures inside CVD diamond
Get PDFDiamond is the strongest and the hardest material known and possess scientifically attractive characteristics. Currently, diamond is not only extracted from the Earth but also can be fabricated in a laboratory. The advantage of synthetic industrial diamond is that it can be manufactured in unlimited quantities and its features might be tailored with respect to a particular application. Diamond is used in a variety of industries and research areas. Diamond possesses high thermal conductivity, is resistant to irradiation and suits perfectly to the harsh environments. It surpasses the properties of other counter semiconductor materials, including Si and GaAs, on several electrical figures of merit. Moreover, due to its extreme strength, diamond exhibits high resistance to scratches and breakages. Thanks to these excellent material properties, diamond devices already find application in sensing in harsh environments for detection of rradiation. Additionally, diamond-based devices possess potential application in other areas, such as electrochemistry, quantum technology and biomedicine. However, advanced manufacturing methods are needed to make effective devices from this challenging substrate. Laser writing with ultrashort pulsed lasers is an effective method for fabrication of structures in three dimensions inside transparent materials. This thesis explores optimisation of laser writing for conductive graphite-based structures inside synthetic diamond substrates and shows routes towards effective diamond devices. Whilst laser writing of conductive structures in synthetic diamond has been demonstrated for more than ten years, much work is still needed to optimise the process conditions for devices, understand the laser written structures, and explore new applications.This thesis presents a variety of advances in ultrashort pulsed laser graphitisation of diamond supported by adaptive optics, providing progress towards exploitation of diamond’s extraordinary characteristics and implementation of diamond devices into current working systems. This thesis focuses on laser written conductive columns that pass vertically through a diamond wafer. An all-carbon device was designed and laser written for characterisation of the electrical properties of the fabricated structures, without post-processing or metallisation. This architecture allows rapid testing of devices all manufactured using the same material. A detailed study was conducted to examine the relationship between laser pulse repetition rate and resistance of laser fabricated graphitic columns. This analysis reveals a surprisingly narrow laser fabrication window with pulse repetition rate, ranging from 200 Hz to 2 kHz, when graphitic wires showed consistent ohmic conductivity. Furthermore, it was demonstrated through varying laser writing speed that the delivered laser dose (defined as number of pulses per distance) is critical in the formation of conductive graphitic pathways. Novel concepts of advanced laser writing are demonstrated to enable fabrication of new devices. It is shown that overwriting of laser generated columns using different pulse repetition rates can modify electrical properties. Particularly, an initially ohmic conductive column can be overwritten with a high pulse repetition rate laser to create a structure showing an asymmetric barrier potential, with diode-like behaviour. It is also shown how a holographic laser process can be used to generate multiple columns simultaneously by splitting the laser beam up into many foci. This can be useful for scaling of devices to large numbers of columns. Finally, functional diamond devices are described that were developed in collaboration and rely upon the advances in laser graphitisation developed in the thesis, for applications in power electronics and detection of high energy particles. A variety of methods are presented for evaluating laser written columns, aside from just electrical properties. Quantitative polarising optical microscopy is demonstrated as an effective way to visualise strain induced by the laser written features. Measurements are given showing the stress generated around graphitic columns and important considerations raised. These techniques are especially important for the design of future photonic devices, such as optical waveguides, that operate based upon refractive index modulation arising from strain
Triggering anger using a virtual reality social scene
Get PDFVirtual reality (VR) simulations may provide a safer way for people with high levels of anger to practise overcoming unhelpful reactions. The first step in such treatment development is to test whether anger can be caused by a simulation of a common triggering situation. The aim was to test whether an intimidating VR social environment raises anger in men and whether the effect is more pronounced in those with problematic anger. A mixed-design experimental study was conducted. Two hundred and sixty-five people were screened: 20 men were allocated to a high anger group based on the clinical cut-off of the Dimensions of Anger Reactions-5 (DAR-5) (> 12) and 22 men to a low anger group (DAR-5 score < 8). Anger was assessed pre- and post-exposure to an intimidating VR lift scenario featuring seven characters. Appraisals of the virtual characters were also assessed. Regression analyses were used to test the effects of anger group and appraisals on anger response whilst controlling for baseline anger. Across all participants, anger significantly increased from pre- to post-VR (t(41) = 3.63, p < .001, d = 0.56). There was a significant effect of group on the extent anger was triggered by the VR scenario (β = 0.277, t(df) = 2.443, p = .019, SE = 2.098) with the high anger group showing a greater anger response. Hostile appraisal of virtual characters (β = 0.416, t(df) = 3.285, p = .002, SE = 0.038) was associated with a greater anger response. The reactions to the virtual reality simulation mirrored what may be expected in the real world. A mildly stressful VR social situation raised anger in all but this was more pronounced in men who have difficulties with anger. VR has the potential to be used in the assessment and treatment of anger
Applying machine-learning and deep-learning to predict depression from brain MRI and identify depression-related brain biology
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The accuracy of grey-matter predictors of depression has remained limited. In this study, brain-based predictors of major depressive disorder (MDD) were trained using machine-learning (Best Linear Unbiased Predictors [BLUP]) and deep-learning (ResNet3D) techniques applied to high-dimensional (voxel-wise) grey-matter structure extracted from T1-weighted structural MRI. The training sample comprised 987 MDD cases and 3934 controls from the UK Biobank. Predictors were evaluated in an independent sub-cohort of 483 MDD cases and 1939 controls from the UK Biobank and replicated in a clinical cohort (DEP-ARREST CLIN) of 64 cases and 32 controls. In the UK Biobank, the BLUP predictor showed a significant association with MDD status (AUC = 0.57; OR = 1.28 [1.15-1.43]; p-value = 1.1×10
-5
), which was confirmed in both males and females. By partitioning the BLUP predictor by brain regions of interest (ROI), we found nominal significance supporting the contribution of previously identified MDD-related ROIs (e.g. hippocampus and amygdala), though none passed multiple testing correction. The BLUP predictor overlapped partially with a polygenic score (PGS) of major depression (AUC = 0.65) but also captured a nominally significant signal that was not captured by the genetic score (combined AUC = 0.66, p-value = 0.024 when compared to PGS alone). No association passed multiple testing correction in the DEP-ARREST CLIN cohort, likely due to the small sample size. In contrast, the deep-learning predictor was not associated with MDD after multiple testing corrections. We estimated the morphometricity of MDD to be 0.061, implying limited potential of a brain-based predictor based on grey-matter structure (maximal AUC = 0.64). While the modest AUC values reiterate the challenge of developing brain-based MDD predictors for clinical applications, our predictors inform future research to explore brain-based relationships between MDD and comorbidities
Protocol of the RADIO-STAR trial: a phase 1 safety and dose finding study of hypofractionated radiotherapy to the stellate ganglia for the treatment of ventricular arrhythmia
Get PDFINTRODUCTION: Sympathetic activation is the hallmark of cardiac disease, driving disease progression and triggering ventricular arrhythmia (VA). Despite optimal medical therapy, many patients experience recurrent VAs refractory to medical therapy, leading to repetitive implantable cardioverter defibrillator (ICD) therapy, worse quality of life and adverse outcomes. Cardiac sympathetic denervation (CSD) through surgical removal of the stellate ganglia is an effective treatment for refractory VAs but carries a high complication rate. We hypothesise that high precision image guided radiotherapy can be used to target the stellate ganglia to achieve CSD non-invasively. METHODS AND ANALYSIS: RADIO-STAR (hypofractionated radiotherapy to the stellate ganglia for ventricular arrhythmia) is a first-in-human, phase 1 safety and dose finding study of radiotherapy to the stellate ganglia in patients with recurrent VAs. Patients with structural heart disease requiring recurrent ICD therapy for VAs are invited to undergo radiotherapy bilaterally to their stellate ganglia with a predetermined sample size of n=13. Radiotherapy dose will be determined by a prespecified dose escalation protocol. The primary outcome is safety defined as any treatment-related grade 3-5 toxicity occurring within 6 months of radiotherapy treatment, as defined by the Common Terminology Criteria for Adverse Events or any treatment-related side effects detected on patient symptom questionnaires and clinical examination during study visits. Secondary outcome measures to evaluate feasibility and efficacy include ability to safely deliver radiotherapy and consequent changes in circulating catecholamines and neuropeptide-Y, heart rate variability, structural changes in the stellate ganglia on MRI imaging and ICD therapy burden. ETHICS AND DISSEMINATION: This study has received ethical approval by the South Central-Oxford B Research Ethics Committee (REC/SC/0005). Study findings will be submitted for publication in peer-reviewed scientific journals and presented at national and/or international scientific conferences. TRIAL REGISTRATION NUMBER: ISRCTN49861434
Protocol for a process and implementation evaluation of the SMARThealth pregnancy hybrid type 2 cluster randomised controlled trial
Get PDFBackground: This protocol outlines the process and implementation evaluation of the SMARThealth Pregnancy (SHP) pragmatic, type 2 hybrid cluster randomised trial conducted in two states in India (Haryana/Telangana). The SHP trial aims to improve the community-level identification, diagnosis, referral and management of women with anaemia, diabetes, and hypertension during pregnancy and in the year after birth. Objectives: The process and implementation evaluation aims to understand how, why, and for whom the SHP intervention may be effective (or not). It aims to identify contextual factors, barriers, and facilitators relevant to the implementation of the intervention, and understand mechanisms and strategies employed during its implementation. Design: The study utilised a process evaluation design. Method: A mixed methods evaluation drawing from realist evaluation, normalisation process theory, the Medical Research Council framework, reach, effectiveness, adoption, implementation and maintenance framework, and Proctor’s typology will be employed for understanding the implementation process. The evaluation will involve focus group discussions and semi-structured interviews with healthcare providers (Accredited Social Health Activist, primary care doctors, and auxiliary nurse midwife), women, and field staff. Quantitative process data describing reach, fidelity, dose, and adoption of intervention will be collected. Observations of trial setup and implementation will be conducted. Both qualitative and quantitative data will be analysed iteratively before the effectiveness outcomes of the SHP trial are available and will subsequently be triangulated with the trial primary outcome evaluation data. Discussion: The findings from this process evaluation will provide an understanding of how the intervention works in practice, its potential to detect and manage anaemia, diabetes and hypertension during pregnancy and in the year after birth, and its scalability as an integrated model for the management of non-communicable diseases in pregnancy/postnatal care
Individual and household factors associated with tungiasis in a marginalized population in Karamoja, northeastern Uganda
Get PDFBackground: Tungiasis is a neglected tropical skin disease caused by adult female fleas which burrow into the skin of people and animals, causing considerable pain and itching. The distribution of the disease is heterogeneous, with Napak district, Karamoja sub-region of northeastern Uganda having the highest disease burden recorded globally. We aimed to determine the factors associated with this high prevalence to inform future intervention strategies. Methods: We conducted a cross-sectional study to identify factors associated with infection of individual children and adults, and a nested case–control study to identify factors for whole households (families). Infected children were identified through mass-screening of children aged 8–14 years between January and March 2022 in 25 villages. Of the 1619 children screened, 210 infected and 358 uninfected children were randomly selected, and their households were enrolled into the study. Observations were made of the homesteads, and structured interviews were conducted with the caregivers. All adults and children in the households were examined. Mixed effect logistic regression analysis was used to identify factors associated with infection of individuals or households. Results: We found children who lived in high-density settlements (manyattas) had more than three times the odds of being infected than those in more open, low-density settlements (adjusted odds ratio aOR 3.51, 95% CI 1.57–7.83, p = 0.002). To our knowledge, this is the first study to show an association of household infection (at least one case) with having a child with a disability (aOR 5.38, 95% CI 1.92–15.03, p = 0.001) and a caregiver who did not show affection to their child (aOR 1.79, 95% CI 1.02–3.13, p = 0.041). For individual adults, those who reported drinking alcohol had four times the odds of infection than those who did not (aOR 4.74, 95% CI 1.93–11.68, p = 0.001). Frequency of washing feet, soap use and house cleanliness were also associated with household infection. Conclusion: Control programs should be developed together with the caregivers to enable them to reduce alcohol use, improve their childcare, hygiene and sanitation practices