Human social groups: A cybernetic account of stability and instability

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The aims of the research were: i) to show that some informal htiman groups are stable; ii) to discover the processes underlying this stability. A third, implicit, aim was the adaptation of cybernetic methodology to small group studies. It was felt that a systems approach would provide a formal, but flexible analytic tool appropriate to the richness and complexity of the phenomenon. Various explanatory hypotheses were constructed, all of which took the variables 'size' and 'level of activity' as the objects of any stabilising process. The hypotheses were tested by laboratory experiment, by longtidudinal, participant-observer studies of natural groups, and by a computer simulation (GROUP-1) that mapped assumptions onto historical data. It was found that when 'size' and 'activity' were maintained within specified limits, this was a consequence of a series of stabilising processes. Once a group became stable, two major sources of disruption were identified, both originating outside the group. These were an external block on activity, or a sudden influx of new members. In the absence of disruption, stability was manifested in the following way. An increase in group size towards its upper boundary triggered a series of repercussions that 'encouraged' members to leave. A decrease triggered a similar and opposite effect. The group's 'level of activity' was shielded from the effects of size change by a series of buffer mechanisms, and so maintained its own independent equilibrium. These quasi-mechanical processes were facilitated by a set of beliefs and techniques (the group's knowledge of how and why to pursue its aims), but the persistence of these beliefs and techniques were themselves dependent on the operation of the stabilising processes. It was concluded that viable groups were constituted as irreductable cybernetic wholes. All processes, physical and informational, supported, but were dependent on, all other process

LEADing together: Partnerships for a Healthier DeKalb

Background: In 2014, the DeKalb County Board of Health (DCBOH) received a three-year Racial and Ethnic Approaches to Community Health (REACH) grant to work with community partners to address health disparities among African Americans in DeKalb County. The project, called Local Efforts toward Addressing Disparities in DeKalb (LEAD DeKalb), relies on a network of partnerships to implement community-based interventions that promote healthy eating and physical activity among African Americans throughout low-income parts of DeKalb County. Methods: The evaluation team developed an online survey to assess LEAD DeKalb staff and partner satisfaction with the partnerships created and the work completed through LEAD DeKalb thus far (n=20, response rate of 71.4%). The 20-question survey was adapted primarily from two sources: the Wilder Collaboration Factors Inventory and the Program Sustainability Assessment Tool. Data analysis was limited to basic descriptive information such as frequencies, percentages, and averages, with comparisons made between DCBOH staff and partners. Results: Partners reported that their organization benefits from being involved in the partnership and attributed a variety of factors to the success of the partnership, including: bringing together diverse stakeholders; exchanging information/knowledge; sharing resources; and developing a shared mission and goals. Identifying new partners and developing a sustainability plan that includes funding, community support, and strong partnerships were identified as areas for improvement. Relevant qualitative findings from key informant interviews were also presented. Conclusions: Two main themes emerged from the data: (1) the network of partnerships is valuable and strong, but may benefit from new partners, and (2) resources (especially funding) are critical for implementing and sustaining the work of the partnership. Taken together, these findings suggest that partnerships are best conceptualized as ongoing processes rather than tasks to complete; and expanding social networks and learning communities allows partners to leverage social, human, and financial capital well beyond the grant period

Estimates of tropical bromoform emissions using an inversion method

Abstract. Bromine plays an important role in ozone chemistry in both the troposphere and stratosphere. When measured by mass, bromoform (CHBr3) is thought to be the largest organic source of bromine to the atmosphere. While seaweed and phytoplankton are known to be dominant sources, the size and the geographical distribution of CHBr3 emissions remains uncertain. Particularly little is known about emissions from the Maritime Continent, which have usually been assumed to be large, and which appear to be especially likely to reach the stratosphere. In this study we aim to reduce this uncertainty by combining the first multi-annual set of CHBr3 measurements from this region, and an inversion process, to investigate systematically the distribution and magnitude of CHBr3 emissions. The novelty of our approach lies in the application of the inversion method to CHBr3. We find that local measurements of a short-lived gas like CHBr3 can be used to constrain emissions from only a relatively small, sub-regional domain. We then obtain detailed estimates of CHBr3 emissions within this area, which appear to be relatively insensitive to the assumptions inherent in the inversion process. We extrapolate this information to produce estimated emissions for the entire tropics (defined as 20° S–20° N) of 225 Gg CHBr3 yr−1. The ocean in the area we base our extrapolations upon is typically somewhat shallower, and more biologically productive, than the tropical average. Despite this, our tropical estimate is lower than most other recent studies, and suggests that CHBr3 emissions in the coastline-rich Maritime Continent may not be stronger than emissions in other parts of the tropics. M. Ashfold thanks the Natural Environment Research Council (NERC) for a research studentship, and is grateful for support through the ERC ACCI project (project number 267760). N. Harris is supported by a NERC Advanced Research Fellowship. This work was supported through the EU SHIVA project, through the NERC OP3 project, and NERC grants NE/F020341/1 and NE/J006246/1. We also acknowledge the Department of Energy and Climate Change for their support in the development of InTEM (contract GA0201). For field site support we thank S.-M. Phang, A. A. Samah and M. S. M. Nadzir of Universiti Malaya, S. Ong and H. E. Ung of Global Satria, Maznorizan Mohamad, L. K. Peng and S. E. Yong of the Malaysian Meteorological Department, the Sabah Foundation, the Danum Valley Field Centre and the Royal Society. This paper constitutes publication no. 613 of the Royal Society South East Asia Rainforest Research Programme.This is the final published version. It first appeared at http://www.atmos-chem-phys.net/14/979/2014/acp-14-979-2014.html

Distinguishing Healthy Ageing from Dementia: A Biomechanical Simulation of Brain Atrophy Using Deep Networks

Biomechanical modeling of tissue deformation can be used to simulate different scenarios of longitudinal brain evolution. In this work, we present a deep learning framework for hyper-elastic strain modelling of brain atrophy, during healthy ageing and in Alzheimer’s Disease. The framework directly models the effects of age, disease status, and scan interval to regress regional patterns of atrophy, from which a strain-based model estimates deformations. This model is trained and validated using 3D structural magnetic resonance imaging data from the ADNI cohort. Results show that the framework can estimate realistic deformations, following the known course of Alzheimer’s disease, that clearly differentiate between healthy and demented patterns of ageing. This suggests the framework has potential to be incorporated into explainable models of disease, for the exploration of interventions and counterfactual examples

Advanced imaging of a histologically confirmed bone infarction of the distal tibia in a Warmblood mare

An 8‐year‐old Warmblood‐cross mare presented for investigation of acute onset left hindlimb lameness. Nuclear scintigraphy identified a marked, focal, increase in radiopharmaceutical uptake in the distal aspect of the left tibia. Radiography revealed a large, oval, multi‐loculated radiolucent area within the medulla of the distal metaphysis of the left tibia. The mare was treated conservatively for 6 months but showed little improvement in the lameness so the owner elected for euthanasia. Post‐mortem computed tomographic imaging revealed a large, oval, hypoattenuating area within the distal tibia, surrounded by a thick, irregular, sclerotic border. The lesion occupied the majority of the medullary cavity but the cortical bone was unaffected. Gross and histopathological examination confirmed a diagnosis of a bone infarction in the medullary cavity of the distal tibia

Rapid and Accurate Assessment of GPCR-Ligand Interactions Using the Fragment Molecular Orbital-Based Density-Functional Tight-Binding Method

The reliable and precise evaluation of receptor–ligand interactions and pair-interaction energy is an essential element of rational drug design. While quantum mechanical (QM) methods have been a promising means by which to achieve this, traditional QM is not applicable for large biological systems due to its high computational cost. Here, the fragment molecular orbital (FMO) method has been used to accelerate QM calculations, and by combining FMO with the density-functional tight-binding (DFTB) method we are able to decrease computational cost 1000 times, achieving results in seconds, instead of hours. We have applied FMO-DFTB to three different GPCR–ligand systems. Our results correlate well with site directed mutagenesis data and findings presented in the published literature, demonstrating that FMO-DFTB is a rapid and accurate means of GPCR–ligand interactions