Capturing the time-varying drivers of an epidemic using stochastic dynamical systems

Epidemics are often modelled using non-linear dynamical systems observed through partial and noisy data. In this paper, we consider stochastic extensions in order to capture unknown influences (changing behaviors, public interventions, seasonal effects etc). These models assign diffusion processes to the time-varying parameters, and our inferential procedure is based on a suitably adjusted adaptive particle MCMC algorithm. The performance of the proposed computational methods is validated on simulated data and the adopted model is applied to the 2009 H1N1 pandemic in England. In addition to estimating the effective contact rate trajectories, the methodology is applied in real time to provide evidence in related public health decisions. Diffusion driven SEIR-type models with age structure are also introduced.Comment: 21 pages, 5 figure

Atomic oxygen effects on LDEF experiment AO171

The Solar Array Materials Passive Long Duration Exposure Facility (LDEF) Experiment (SAMPLE), AO171, contained in total approximately 100 materials and materials processes with a 300 specimen complement. With the exception of experiment solar cell and solar cell modules, all test specimens were weighed before flight, thus allowing an accurate determination of mass loss as a result of space exposure. Since almost all of the test specimens were thermal vacuum baked before flight, the mass loss sustained can be attributed principally to atomic oxygen attack. The atomic oxygen effects observed and measured in five classes of materials is documented. The atomic oxygen reactivity values generated for these materials are compared to those values derived for the same materials from exposures on short term shuttle flights. An assessment of the utility of predicting long term atomic oxygen effects from short term exposures is given. This experiment was located on Row 8 position A which allowed all experiment materials to be exposed to an atomic oxygen fluence of 6.93 x 10(exp 21) atoms/cm(sup 2) as a result of being positioned 38 degrees off the RAM direction

Network Structures and Dynamics Of Early Dementia Events Recorded in Primary Care Electronic Health Records

Background: Identifying early signs of heterogeneous conditions like dementia is challenging. We used electronic health records (EHR) and data-driven methods in order to represent prodromal dementia as a dynamic temporal network of healthcare events and move beyond reductionist representations of complex syndromes. / Methods: We used UK primary care EHR data from Clinical Practice Research Datalink (CPRD) through the CALIBER resource and identified patients with a dementia diagnosis. We constructed a weighted, undirected network. We calculated centrality measures of the network and compared three community detection algorithms, Louvain, InfoMAP and Walktrap. Distinctive temporal communities of events in two year windows were derived, and we explored community membership, interactions and dynamics using evaluation measures including Jaccard distance, modularity, Rand Index and Normalised Mutual Information. / Results: We analysed data from 89,102 patients, where nodes (n=816) were connected to edges (n=392,345) based on the frequency with which two features were recorded in the same time window. Across the whole prodrome, repeated cardiovascular medications accounted for 22% of the network edges, followed by repeated central nervous system medications, accounting for 5% of edges. Cardiovascular conditions had the highest eigen centrality (influence on the entire network structure) and QRISK2 and malignant neoplasms had the greatest betweenness centrality (bridge between events). Louvin had the highest modularity and clustered the temporal network into six communities: The largest community was enriched for respiratory diseases (late-prodrome) and circulatory conditions (mid). Community 2 was enriched for musculoskeletal conditions (late), and Community 3 for administrative events (early) and nervous system conditions (late). In the early prodrome, there were more transitions between communities, however from 10 years to diagnosis, most events occurred within communities. / Conclusion: By understanding the interdependencies of conditions and associated medications across a disease network, we can deepen our understanding of prodromal dementia and create an accurate phenotype of the earliest stages of cognitive decline

Initial Acoustoelastic Measurements in Olivine: Investigating the Effect of Stress on P- and S-Wave Velocities

It is well known that elasticity is a key physical property in the determination of the structure and composition of the Earth and provides critical information for the interpretation of seismic data. This study investigates the stress-induced variation in elastic wave velocities, known as the acoustoelastic effect, in San Carlos olivine. A recently developed experimental ultrasonic acoustic system, the Directly Integrated Acoustic System Combined with Pressure Experiments (DIASCoPE), was used with the D-DIA multi-anvil apparatus to transmit ultrasonic sound waves and collect the reflections. We use the DIASCoPE to obtain longitudinal (P) and shear (S) elastic wave velocities from San Carlos olivine at pressures ranging from 3.2–10.5 GPa and temperatures from 450–950°C which we compare to the stress state in the D-DIA derived from synchrotron X-ray diffraction. We use elastic-plastic self-consistent (EPSC) numerical modeling to forward model X-ray diffraction data collected in D-DIA experiments to obtain the macroscopic stress on our sample. We can observe the relationship between the relative elastic wave velocity change (ΔV/V) and macroscopic stress to determine the acoustoelastic constants, and interpret our observations using the linearized first-order equation based on the model proposed by Hughes and Kelly (1953), https://doi.org/10.1103/physrev.92.1145. This work supports the presence of the acoustoelastic effect in San Carlos olivine, which can be measured as a function of pressure and temperature. This study will aid in our understanding of the acoustoelastic effect and provide a new experimental technique to measure the stress state in elastically deformed geologic materials at high pressure conditions

The impact of Covid-19 on families, children aged 0-4 and pregnant women in Tower Hamlets: Wave One Survey Findings

Families in Tower Hamlets is an ongoing research project led by University College London into the impact of the Covid-19 pandemic on the lives of families with young children and pregnant women. This report is of initial findings from the ‘first 500’ respondents, who completed the survey between July and November 2020. We present findings in terms of seven main ethnic groups that broadly represent proportions in the local population: one third of the population identify as White British and White Irish; a further third identify as Bangladeshi; and a final third identify with a wide range of other ethnicities. There are marked differences within this group so we have used the categories: Other White; Asian Other; Somali; Black & Black Other; and Other ethnic group to illustrate the experiences of respondents. With this lens of ethnicity, combined with analysis by household income, we can see certain clear patterns arising. Here, we focus on five main areas: family livelihoods; housing and environment; supporting children at home; health and social support services; and participants’ own health and mental health. Subsequent outputs will present findings in more detail

Income, ethnic diversity and family life in East London during the first wave of the pandemic: An assets approach

Objective: This paper reports first results from a survey of 992 parents and parents to be living in an ethnically diverse and socio-economically unequal borough of East London during the coronavirus pandemic that reduced mobility, closed services and threatened public health. / Background: Little is known about the place based impacts of the pandemic on families with young children. We describe the living circumstances of families with children under five or expecting a baby living in Tower Hamlets during the Coronavirus pandemic in 2020, and then examine the relative importance of household characteristics such as ethnicity and household income for adverse impacts on survey respondents, as seen in mental health outcomes. / Method: a community survey sample recruited with support from the local council comprised 75% mothers/pregnant women, 25% fathers/partners of pregnant women. Reflecting the borough population, 35 percent were White British or Irish and 36 percent were Bangladeshi, and the remainder were from a wide range of ethnic backgrounds. Adopting an assets based approach, we describe material, familial and community assets using three household income bands and seven ethnic groups. We then use regressions to identify which assets were most important in mitigating adversity. / Results: We find that material assets (income, employment, food insecurity, housing quality) were often insecure and in decline but familial assets (home caring practices, couple relationships) were largely sustained. Community assets (informal support, service provision) were less available or means of access had changed. Our analyses find that while descriptively ethnicity structured adverse impacts of the pandemic related changes to family life, income and couple relationships were the most important assets for mitigating adversity as seen in mental health status. / Conclusion: Supporting family assets will require close attention to generating local and decent work as well as enhancing access to community assets

Interim Briefing Report. The First 500: The impact of Covid-19 on families, children aged 0-4 and pregnant women in Tower Hamlets

Families in Tower Hamlets is an ongoing research project led by University College London into the impact of the Covid-19 pandemic on the lives of families with young children and pregnant women. This report is of initial findings from the ‘first 500’ respondents, who completed the survey between July and September 2020. We present findings in terms of three main ethnic groups that broadly represent proportions in the local population: one third of the population identify as White British and White Irish; a further third identify as Bangladeshi; and a final third identify with a wide range of other ethnicities which we have had to present as ‘Other ethnicity’ in this report and we acknowledge this is unlikely to do justice to the range of experience within this group. With this lens of ethnicity, combined with analysis by household income, we can see certain clear patterns arising. Here, we focus on five main areas: family livelihoods; housing and environment; supporting children at home; health and social support services; and participants’ own health and mental health. Subsequent outputs will present findings in more detail

What Family Circumstances, During COVID-19, Impact on Parental Mental Health in an Inner City Community in London?

The introduction of lockdown due to a public health emergency in March 2020 marked the beginning of substantial changes to daily life for all families with young children. Here we report the experience of families from London Borough of Tower Hamlets with high rates of poverty and ethnic and linguistic diversity. This inner city community, like communities worldwide, has experienced a reduction or closure in access to education, support services, and in some cases, a change in or loss of income, job, and food security. Using quantitative survey items (N = 992), we examined what differences in family circumstances, for mothers and fathers of young children aged 0-5 living in Tower Hamlets, during March 2020 to November 2020, were associated with their mental health status. We measure parental mental health using symptoms of depression (self-report: Patient Health Questionnaire depression scale: PHQ-8), symptoms of anxiety levels (self-report: General Anxiety Disorder: GAD-7), and perceptions of direct loneliness. We find parental mental health difficulties are associated with low material assets (financial security, food security, and children having access to outside space), familial assets (parents time for themselves and parent status: lone vs. cohabiting), and community assets (receiving support from friends and family outside the household). South Asian parents and fathers across ethnicities were significantly more likely to experience mental health difficulties, once all other predictors were accounted for. These contributing factors should be considered for future pandemics, where restrictions on people's lives are put in place, and speak to the importance of reducing financial insecurity and food insecurity as a means of improving the mental health of parents

Asynchronous sequential circuit design using pass transistor iterative logic arrays

The iterative logic array (ILA) is introduced as a new architecture for asynchronous sequential circuits. This is the first ILA architecture for sequential circuits reported in the literature. The ILA architecture produces a very regular circuit structure. Moreover, it is immune to both 1-1 and 0-0 crossovers and is free of hazards. This paper also presents a new critical race free STT state assignment which produces a simple form of design equations that greatly simplifies the ILA realizations