Valve degradation detector

To determine corrosive degradation of valve while it is in service, detect changes in surface roughness or presence of corrosive layers at junction of poppet and seat by measuring temperature gradients created across junction by small heat source

Understanding cognitive dysfunction in secondary progressive multiple sclerosis using functional and structural MRI

This thesis concerns a 2 year follow-up study of people with secondary progressive multiple sclerosis (SPMS). I investigate: (1) cognitive performance of SPMS and changes over time, (2) the classification of cognitive impairment and predictors of this, (3) mechanisms underlying the SPMS phenotype with and without cognitive impairment using functional and structural MRI. The literature has highlighted the input of executive dysfunction in the cognitive profile of SPMS over and above that seen in other multiple sclerosis (MS) phenotypes. I looked at cognitive performance in SPMS, and predictors of this in this pure SPMS cohort study. I found that being employed, having higher IQ, more premorbid leisure interests, and higher qualifications mitigate against negative cognitive outcomes in SPMS. Additionally, anxiety, even when not reaching clinically diagnostic levels, impacts on tests of information processing speed, verbal working memory, and executive function in SPMS. The symbol digit modality test (SDMT) at baseline is predicted by MS lower limb disability outcome measures; the Expanded Disability Status Scale (EDSS) and timed 25 foot walk (T25FW) which emphasises the role of the SDMT as an adjunctive measure of clinical disability prediction in studies. I show that decline on the SDMT at follow-up is purely predicted by cognitive measures of information processing speed and working memory at either timepoint, supporting, and furthering, the evidence for the SDMT as a sentinel assessment of cognitive performance in SPMS. These findings inform future longitudinal cognitive studies in SPMS, particularly with regards to the importance of tests of executive function, and important associations with clinical outcomes in a highly disabled cohort. I also considered the threshold for classifying cognitive impairment, and its implications. There is marked heterogeneity in these thresholds due to the lack of current consensus on a diagnostic criteria. Using a higher threshold for cognitive impairment in my studies strengthened the associations with clinically relevant outcomes. Additionally, unemployment showed the greatest association with cognitive impairment regardless of criteria used. I found that assessments of information processing speed, verbal memory, and executive function had the greatest input to cognitive impairment in SPMS. These findings indicate the importance of these cognitive domains and demographic factors when evaluating cognitive status in SPMS. These results will guide the international consensus on how best to measure cognitive impairment in SPMS, and in MS more broadly. Posterior and deep resting state networks (RSNs) have been shown to be altered in resting state functional MRI (rs-fMRI) studies of progressive MS phenotypes. I confirm this using functional connectivity (FC) and highlight that this is mainly in terms of cognitive RSNs in SPMS versus healthy controls using a global rs-fMRI analysis technique. Additionally, with cognitive impairment in SPMS, I show that there are key attentional RSN FC reductions. I further highlight the importance of more stringent classification criteria of cognitive impairment to allow for more detailed evaluation of dynamic FC changes, that are missed when using a lenient criteria. Over time, the development of cognitive impairment in SPMS from a preserved state appears to relate to reduced FC in working memory, posterior default mode (DMN) and visual RSNs, and increased FC in the executive control, and more anterior DMN hubs at baseline. Therefore, alterations in posterior cognitive and executive RSNs may inform cognitive status in SPMS. These results provide, to my knowledge, the first longitudinal rs-fMRI study of cognitive status in SPMS. Regional grey matter atrophy has been shown to be greater in SPMS then in other MS phenotypes. I found that SPMS cognitive impairment is associated with grey matter volume, cortical grey matter volume, and deep grey matter and regional deep grey matter atrophy. I also highlighted that proportionally, within the cerebellum, there are greater percentage changes in FC versus volume in those with SPMS with cognitive impairment versus in SPMS overall. These findings therefore show the importance of deeper grey matter atrophy in SPMS underlying cognitive impairment, and indicate the need for a longitudinal study of rs-fMRI and regional grey matter MRI metrics to understand the interplay of underlying mechanisms in more detail

Community based trial of home blood pressure monitoring with nurse-led telephone support in patients with stroke or transient ischaemic attack recently discharged from hospital.

BACKGROUND: High blood pressure in patients with stroke increases the risk of recurrence but management in the community is often inadequate. Home blood pressure monitoring may increase patients' involvement in their care, increase compliance, and reduce the need for patients to attend their General Practitioner if blood pressure is adequately controlled. However the value of home monitoring to improve blood pressure control is unclear. In particular its use has not been evaluated in stroke patients in whom neurological and cognitive ability may present unique challenges. DESIGN: Community based randomised trial with follow up after 12 months. PARTICIPANTS: 360 patients admitted to three South London Stroke units with stroke or transient ischaemic attack within the past 9 months will be recruited from the wards or outpatients and randomly allocated into two groups. All patients will be visited by the specialist nurse at home at baseline when she will measure their blood pressure and administer a questionnaire. These procedures will be repeated at 12 months follow up by another researcher blind as to whether the patient is in intervention or control group. INTERVENTION: INTERVENTION patients will be given a validated home blood pressure monitor and support from the specialist nurse. Control patients will continue with usual care (blood pressure monitoring by their practice). Main outcome measures in both groups after 12 months: 1. Change in systolic blood pressure.2. Cost effectiveness: Incremental cost of the intervention to the National Health Service and incremental cost per quality adjusted life year gained

From Questions to Effective Answers: On the Utility of Knowledge-Driven Querying Systems for Life Sciences Data

We compare two distinct approaches for querying data in the context of the life sciences. The first approach utilizes conventional databases to store the data and intuitive form-based interfaces to facilitate easy querying of the data. These interfaces could be seen as implementing a set of "pre-canned" queries commonly used by the life science researchers that we study. The second approach is based on semantic Web technologies and is knowledge (model) driven. It utilizes a large OWL ontology and same datasets as before but associated as RDF instances of the ontology concepts. An intuitive interface is provided that allows the formulation of RDF triples-based queries. Both these approaches are being used in parallel by a team of cell biologists in their daily research activities, with the objective of gradually replacing the conventional approach with the knowledge-driven one. This provides us with a valuable opportunity to compare and qualitatively evaluate the two approaches. We describe several benefits of the knowledge-driven approach in comparison to the traditional way of accessing data, and highlight a few limitations as well. We believe that our analysis not only explicitly highlights the specific benefits and limitations of semantic Web technologies in our context but also contributes toward effective ways of translating a question in a researcher's mind into precise computational queries with the intent of obtaining effective answers from the data. While researchers often assume the benefits of semantic Web technologies, we explicitly illustrate these in practice

Parallel-Jaw Gripper and Grasp Co-Optimization for Sets of Planar Objects

We propose a framework for optimizing a planar parallel-jaw gripper for use with multiple objects. While optimizing general-purpose grippers and contact locations for grasps are both well studied, co-optimizing grasps and the gripper geometry to execute them receives less attention. As such, our framework synthesizes grippers optimized to stably grasp sets of polygonal objects. Given a fixed number of contacts and their assignments to object faces and gripper jaws, our framework optimizes contact locations along these faces, gripper pose for each grasp, and gripper shape. Our key insights are to pose shape and contact constraints in frames fixed to the gripper jaws, and to leverage the linearity of constraints in our grasp stability and gripper shape models via an augmented Lagrangian formulation. Together, these enable a tractable nonlinear program implementation. We apply our method to several examples. The first illustrative problem shows the discovery of a geometrically simple solution where possible. In another, space is constrained, forcing multiple objects to be contacted by the same features as each other. Finally a toolset-grasping example shows that our framework applies to complex, real-world objects. We provide a physical experiment of the toolset grasps.Comment: 2023 IEEE IROS conferenc

Predictors of measles vaccination coverage among children 6-59 months of age in the Democratic Republic of the Congo.

BackgroundMeasles is a significant contributor to child mortality in the Democratic Republic of the Congo (DRC), despite routine immunization programs and supplementary immunization activities (SIA). Further, national immunization coverage levels may hide disparities among certain groups of children, making effective measles control even more challenging. This study describes measles vaccination coverage and reporting methods and identifies predictors of vaccination among children participating in the 2013-2014 DRC Demographic and Health Survey (DHS).MethodsWe examined vaccination coverage of 6947 children aged 6-59 months. A multivariate logistic regression model was used to identify predictors of vaccination among children reporting vaccination via dated card in order to identify least reached children. We also assessed spatial distribution of vaccination report type by rural versus urban residence.ResultsUrban children with educated mothers were more likely to be vaccinated (OR = 4.1, 95% CI: 1.6, 10.7) versus children of mothers with no education, as were children in wealthier rural families (OR = 2.9, 95% CI: 1.9, 4.4). At the provincial level, urban areas more frequently reported vaccination via dated card than rural areas.ConclusionsResults indicate that, while the overall coverage level of 70% is too low, socioeconomic and geographic disparities also exist which could make some children even less likely to be vaccinated. Dated records of measles vaccination must be increased, and groups of children with the greatest need should be targeted. As access to routine vaccination services is limited in DRC, identifying and targeting under-reached children should be a strategic means of increasing country-wide effective measles control