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4,263 results on '"SIMPSON, MICHAEL"'

9. Misinformation Mitigation under Differential Propagation Rates and Temporal Penalties

Author

Simpson, Michael, Hashemi, Farnoosh, and Lakshmanan, Laks V. S.

Subjects
Computer Science - Social and Information Networks, Computer Science - Data Structures and Algorithms
Abstract

We propose an information propagation model that captures important temporal aspects that have been well observed in the dynamics of fake news diffusion, in contrast with the diffusion of truth. The model accounts for differential propagation rates of truth and misinformation and for user reaction times. We study a time-sensitive variant of the \textit{misinformation mitigation} problem, where $k$ seeds are to be selected to activate a truth campaign so as to minimize the number of users that adopt misinformation propagating through a social network. We show that the resulting objective is non-submodular and employ a sandwiching technique by defining submodular upper and lower bounding functions, providing data-dependent guarantees. In order to enable the use of a reverse sampling framework, we introduce a weighted version of reverse reachability sets that captures the associated differential propagation rates and establish a key equivalence between weighted set coverage probabilities and mitigation with respect to the sandwiching functions. Further, we propose an offline reverse sampling framework that provides $(1 - 1/e - \epsilon)$-approximate solutions to our bounding functions and introduce an importance sampling technique to reduce the sample complexity of our solution. Finally, we show how our framework can provide an anytime solution to the problem. Experiments over five datasets show that our approach outperforms previous approaches and is robust to uncertainty in the model parameters., Comment: 19 pages, VLDB 2022

Published
2022

13. A genome-wide meta-analysis of palmoplantar pustulosis implicates TH2 responses and cigarette smoking in disease pathogenesis

Author

Abraham, Thamir, Ali, Muhmad, August, Suzannah, Baudry, David, Becher, Gabrielle, Bewley, Anthony, Brown, Victoria, Cornelius, Victoria, Ghaffar, Sharizan, Ingram, John, Kavakleiva, Svetlana, Kelly, Susan, Khorshid, Mohsen, Lachmann, Helen, Ladoyanni, Effie, McAteer, Helen, McKenna, John, Meynell, Freya, Patel, Prakash, Pink, Andrew, Powell, Kingsley, Pushparajah, Angela, Sinclair, Catriona, Wachsmuth, Rachel, Hernandez-Cordero, Ariana, Thomas, Laurent, Smail, Alice, Lim, Zhao Qin, Saklatvala, Jake R., Chung, Raymond, Curtis, Charles J., Baum, Patrick, Visvanathan, Sudha, Burden, A. David, Cooper, Hywel L., Dunnill, Giles, Griffiths, Christopher E.M., Levell, Nick J., Parslew, Richard, Reynolds, Nick J., Wahie, Shyamal, Warren, Richard B., Wright, Andrew, Simpson, Michael, Hveem, Kristian, Barker, Jonathan N., Dand, Nick, Løset, Mari, Smith, Catherine H., and Capon, Francesca

Published
2024
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15. An LGR6 frameshift variant abrogates receptor expression on select leukocyte subsets and is associated with viral infections

Author

Akhtar, Shaheen, Anwar, Mohammad, Arciero, Elena, Asgar, Omar, Ashraf, Samina, Bidi, Saeed, Breen, Gerome, Broster, James, Chaudhary, Shabana, Chung, Raymond, Clinch, Megan, Collier, David, Colligan, Grainne, Curtis, Charles J., Deloukas, Panos, Durham, Ceri, Durrani, Faiza, Eto, Fabiola, Finer, Sarah, Gafton, Joseph, Angel Garcia, Ana Cristina, Griffiths, Chris, Harvey, Joanne, van Heel, David A., Heng, Teng, Hodgson, Sam, Huang, Qin Qin, Hurles, Matt, Hunt, Karen A, Hussain, Shapna, Islam, Kamrul, Iyer, Vivek, Jacobs, Benjamin M., Khan, Ahsan, Langenberg, Claudia, Lavery, Cath, Lee, Sang Hyuck, MacArthur, Daniel, Malik, Sidra, Malawsky, Daniel, Martin, Hilary, Mason, Dan, Mathur, Rohini, Mazid, Mohammed Bodrul, McDermott, John, Morton, Caroline, Newman, Bill, Owor, Elizabeth, Qureshi, Asma, Ramachandrappa, Shwetha, Raza, Mehru, Russell, Jessry, Safa, Nishat, Samuel, Miriam, Simpson, Michael, Solly, John, Spreckley, Marie, Stow, Daniel, Taylor, Michael, Trembath, Richard C., Tricker, Karen, Walter, Klaudia, Winckley, Caroline, Wood, Suzanne, Wright, John, Zengeya, Ishevanhu, Zöllner, Julia, Gomez, Esteban A., De Matteis, Roberta, Udomjarumanee, Palita, Munroe, Patricia B., and Dalli, Jesmond

Published
2024
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16. On loss characterisation and minimisation in high-performance reciprocating-piston expanders

Author

Simpson, Michael and Markides, Christos

Abstract

Reciprocating-piston expanders are being considered for a range of clean-energy applications, including small- to medium-scale organic Rankine cycle (ORC) engines for conversion of low-grade heat to power, and compressed air and pumped thermal energy storage (CAES, PTES) to help integrate intermittent renewables. At large scale, turbines remain the dominant technology, but at scales of 10 - 100s of kilowatts, reciprocating-piston expanders can offer high efficiency at large pressure ratios, robust part-load performance, and affordable manufacture. Further advantages are available in compressed air energy storage applications, where the potential exists to operate a single reciprocating-piston machine as both compressor and expander. Although there is a wealth of experience in reciprocating-piston machines for internal combustion engines and compressors, quantitative understanding of the particular loss mechanisms which influence reciprocating expanders is less well-established, as a consequence of operating without combustion, and at different temperatures and valve timings. This thesis describes the development and validation of a lumped-mass piston expander model by means of experimental data and computational fluid dynamics (CFD) simulations. The model replicates the cylinder pressure and temperature to a high degree of accuracy, and captures trends in gas-wall heat transfer, though with slight discrepancies in instantaneous magnitudes. The model accounts for frictional losses, and a time-resolved exergy calculation has been introduced to attribute losses to particular thermodynamic and mechanical processes occurring within the device, at both design conditions and part-load operation. Surrogate-model-based optimisation approaches have been demonstrated to optimise an expander geometry and valve timings. By considering a broad range of possible operating conditions and geometries, a set of performance maps are developed to provide insights into the relative magnitudes of the different loss mechanisms that should be considered within the design process. The role of piston expanders in ORC systems is investigated here in multiple waste heat recovery applications, such as recovering heat from stationary internal combustion engines. The piston expander is compared to and contrasted with screw expanders for a broad range of possible ORC working fluids. Unlike previous studies, the expansion device and working fluid selection are carried out simultaneously by means of an integrated optimisation process, ensuring that performance interactions between the expansion device and working fluid properties are captured. When capturing heat from the exhaust gas of the stationary internal combustion engine, a two-stage screw expander is found to provide the highest power output and efficiency, with acetone found to be the optimal working fluid, while a single-stage piston expander offers the lowest specific investment cost and payback time. The relative merits of piston expanders and small-scale radial-inflow turbines for a fluctuating heat source are also assessed, for low-temperature (<100 °C) and high-temperature (400-600 °C) waste heat. At low temperatures, radial-inflow turbines are found to offer both higher isentropic efficiency and lower cost per unit power, while at high temperatures the reciprocating-piston expander is found to be the more economical option, demonstrating lower specific costs as well as a greater robustness to part-load conditions. Building on this finding, an in-depth assessment is carried out into two competing configurations of stationary internal combustion engines paired with ORC engines for building heat and power needs, using reciprocating-piston expanders for the ORC engine in each case. As current ORC engines are limited to small-scale production and tend to face high integration costs due to the custom nature of each installation, building energy consumption data from a set of thirty supermarkets is used to explore the economic feasibility of a common internal combustion and ORC engine design that could offer greater economies of scale. In the first configuration considered, the ORC engine recovers heat from both the exhaust gas and cooling jacket water of the stationary engine, while in the second, heat is extracted only from the exhaust gases, with the condensing temperature of the ORC engine deliberately raised well above ambient in order to allow heat to be rejected from the ORC engine's condenser to the building heating system. The former is found to offer considerably higher power and lower specific investment costs, but the economic returns are inconsistent across the set of buildings, while the second configuration demonstrates favourable payback periods of 3.5-7.5 years for all thirty of the buildings considered, offering much greater scope for larger manufacturing volumes and associated reductions in the unit price and competitiveness of these systems. The design and optimisation of a set of reciprocating-piston engines for small-scale CAES systems is performed. An initial feasibility study identifies two overall architectures for the CAES system as being of particular interest, and these are assessed from a technoeconomic standpoint. The on- and off-design performance of appropriately sized reciprocating-piston machines are simulated in order to quantify the realistic technical and commercial performance of these systems. Valve timing strategies are proposed for efficient charging and discharging of the preferred system configuration in fixed- and variable-speed operation, with variable-speed part-load operation found to deliver higher efficiency than fixed-speed even with fully variable valve timing. Consideration is given to mitigation of the main loss mechanisms within the system and the piston machines in particular, with a strong sensitivity to piston ring leakage identified for high-pressure stages. Based on broad parameter space exploration and specific case studies of piston expander operation, this work aims to highlight favourable opportunities for high-efficiency reciprocating machines and demonstrates the use of a lumped-mass model for determining relevant loss mechanisms and identifying optimal designs at component- and system-level, with a view to accelerating appropriate deployment of these machines for selected clean-energy applications.

Published
2022
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22. Cross-Comparison of Inflammatory Skin Disease Transcriptomics Identifies PTEN as a Pathogenic Disease Classifier in Cutaneous Lupus Erythematosus

Author

Aevermann, Brian D., Di Domizio, Jeremy, Olah, Peter, Saidoune, Fanny, Armstrong, John M., Bachelez, Hervé, Barker, Jonathan, Haniffa, Muzlifah, Julia, Valerie, Juul, Kasper, Krishnaswamy, Jayendra Kumar, Litman, Thomas, Parsons, Ian, Sarin, Kavita Y., Schmuth, Matthias, Sierra, Michael, Simpson, Michael, Homey, Bernhard, Griffiths, Christopher E.M., Scheuermann, Richard H., and Gilliet, Michel

Published
2024
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30. THE CALIFORNIA PHENOLOGY COLLECTIONS NETWORK: USING DIGITAL IMAGES TO INVESTIGATE PHENOLOGICAL CHANGE IN A BIODIVERSITY HOTSPOT

Author

Yost, Jenn M, Pearson, Katelin D, Alexander, Jason, Gilbert, Edward, Hains, Layla Aerne, Barry, Teri, Bencie, Robin, Bowler, Peter, Carter, Benjamin, Crowe, Rebecca E, Dean, Ellen, Der, Joshua, Fisher, Amanda, Fisher, Kirsten, Flores-Renteria, Lluvia, Guilliams, C. Matt, Hatfield, Colleen, Hendrickson, Larry, Huggins, Tom, Janeway, Lawrence, Lay, Christopher, Litt, Amy, Markos, Staci, Mazer, Susan J, Mccamish, Danny, Mcdade, Lucinda, Mesler, Michael, Mishler, Brent, Nazaire, Mare, Rebman, Jon Paul, Rosengreen, Lars, Rundel, Philip W, Potter, Dan, Sanders, Andrew C., Seltmann, Katja C, Simpson, Michael G, Wahlert, Gregory A, Waselkov, Katherine, Williams, Kimberlyn, Wilson, Paul S, and BioStor

Published
2020

34. Visual Entropy and the Visualization of Uncertainty

Author

Holliman, Nicolas S., Coltekin, Arzu, Fernstad, Sara J., McLaughlin, Lucy, Simpson, Michael D., and Woods, Andrew J.

Subjects
Computer Science - Graphics, Computer Science - Human-Computer Interaction, Computer Science - Information Theory
Abstract

Background: Even though data visualizations (and underlying data) almost always contain uncertainty, it remains complex to communicate and interpret uncertainty representations. Consequently, uncertainty visualizations for non-expert audiences are rare. Objective: our aim is to rigorously define and evaluate the novel use of visual entropy as a measure of shape that allows us to construct an ordered scale of glyphs for use in representing both uncertainty and value in 2D and 3D environments. Method: We use sample entropy as a numerical measure of visual entropy to construct a set of glyphs using R and Blender which vary in their complexity. Results: an exact binomial analysis of a pairwise comparison of the glyphs shows a majority of participants (n = 87) ordered each glyph as predicted by the visual entropy score with large effect size (Cohen's g > 0.25). We also evaluate whether the glyphs effectively represent uncertainty using a signal detection method in a search task. Participants (n = 15) were able to find glyphs representing uncertainty with high sensitivity and low error rates. Conclusion: visual entropy is a successful novel approach to representing ordered data and provides a channel that can allow the uncertainty of a measure to be presented alongside its mean value., Comment: 12 pages

Published
2019

40. Reverse Prevention Sampling for Misinformation Mitigation in Social Networks

Author

Simpson, Michael, Srinivasan, Venkatesh, and Thomo, Alex

Subjects
Computer Science - Social and Information Networks, Physics - Physics and Society
Abstract

In this work, we consider misinformation propagating through a social network and study the problem of its prevention. In this problem, a "bad" campaign starts propagating from a set of seed nodes in the network and we use the notion of a limiting (or "good") campaign to counteract the effect of misinformation. The goal is to identify a set of $k$ users that need to be convinced to adopt the limiting campaign so as to minimize the number of people that adopt the "bad" campaign at the end of both propagation processes. This work presents \emph{RPS} (Reverse Prevention Sampling), an algorithm that provides a scalable solution to the misinformation mitigation problem. Our theoretical analysis shows that \emph{RPS} runs in $O((k + l)(n + m)(\frac{1}{1 - \gamma}) \log n / \epsilon^2 )$ expected time and returns a $(1 - 1/e - \epsilon)$-approximate solution with at least $1 - n^{-l}$ probability (where $\gamma$ is a typically small network parameter and $l$ is a confidence parameter). The time complexity of \emph{RPS} substantially improves upon the previously best-known algorithms that run in time $\Omega(m n k \cdot POLY(\epsilon^{-1}))$. We experimentally evaluate \emph{RPS} on large datasets and show that it outperforms the state-of-the-art solution by several orders of magnitude in terms of running time. This demonstrates that misinformation mitigation can be made practical while still offering strong theoretical guarantees., Comment: arXiv admin note: text overlap with arXiv:1404.0900, arXiv:1212.0884 by other authors

Published
2018

42. Mitochondria function associated genes contribute to Parkinson’s Disease risk and later age at onset

Author

Billingsley, Kimberley J, Barbosa, Ines A, Bandrés-Ciga, Sara, Quinn, John P, Bubb, Vivien J, Deshpande, Charu, Botia, Juan A, Reynolds, Regina H, Zhang, David, Simpson, Michael A, Blauwendraat, Cornelis, Gan-Or, Ziv, Gibbs, J Raphael, Nalls, Mike A, Singleton, Andrew, Ryten, Mina, and Koks, Sulev

Subjects
Aging, Brain Disorders, Neurosciences, Parkinson's Disease, Neurodegenerative, Genetics, 2.1 Biological and endogenous factors, Aetiology, Neurological, International Parkinson’s Disease Genomics Consortium, Medical genetics, Risk factors
Abstract

Mitochondrial dysfunction has been implicated in the etiology of monogenic Parkinson's disease (PD). Yet the role that mitochondrial processes play in the most common form of the disease; sporadic PD, is yet to be fully established. Here, we comprehensively assessed the role of mitochondrial function-associated genes in sporadic PD by leveraging improvements in the scale and analysis of PD GWAS data with recent advances in our understanding of the genetics of mitochondrial disease. We calculated a mitochondrial-specific polygenic risk score (PRS) and showed that cumulative small effect variants within both our primary and secondary gene lists are significantly associated with increased PD risk. We further reported that the PRS of the secondary mitochondrial gene list was significantly associated with later age at onset. Finally, to identify possible functional genomic associations we implemented Mendelian randomization, which showed that 14 of these mitochondrial function-associated genes showed functional consequence associated with PD risk. Further analysis suggested that the 14 identified genes are not only involved in mitophagy, but implicate new mitochondrial processes. Our data suggests that therapeutics targeting mitochondrial bioenergetics and proteostasis pathways distinct from mitophagy could be beneficial to treating the early stage of PD.

Published
2019

49. Differences in Clinical Features and Comorbid Burden between HLA-C∗06:02 Carrier Groups in >9,000 People with Psoriasis

Author

Evans, Ian, Murphy, Ruth, McPherson, Tess, Kleyn, Elise, Laws, Philip, Becher, Gabrielle, Bewley, Anthony, Rashid, Amir, Alabas, Oras, Morrison, Simon, Ahmed, Shehnaz, Pearson, Eleanor, Richards, Josh, Mackenzie, Teena, Kirby, Brian, Burden, David, Lawson, Linda, McElhone, Kathleen, Ormerod, Anthony, Owen, Caroline, Aldoori, Nadia, Ali, Mahmud, Anstey, Alex, Antony, Fiona, Archer, Charles, August, Suzanna, Balasubramaniam, Periasamy, Baxter, Kay, Bonsall, Alexandra, Brown, Victoria, Burova, Katya, Butt, Aamir, Caswell, Mel, Cliff, Sandeep, Costache, Mihaela, Darne, Sharmela, Davies, Emily, DeGiovanni, Claudia, Desai, Trupti, DeSilva, Bernadette, Diba, Victoria, Domanne, Eva, Dymond, Harvey, Fahy, Caoimhe, Ferguson, Leila, Gkini, Maria-Angeliki, Godwin, Alison, Hammonds, Fiona, Johnson, Sarah, Joseph, Teresa, Kalavala, Manju, Khorshid, Mohsen, Labinoti, Liberta, Lawson, Nicole, Layton, Alison, Lees, Tara, Levell, Nick, Lewis, Helen, Lyon, Calum, McBride, Sandy, McCormack, Sally, McKenna, Kevin, Mellor, Serap, Norris, Paul, Popli, Urvi, Perera, Gay, Ponnambath, Nabil, Ramsay, Helen, Ranasinghe, Aruni, Reeken, Saskia, Rose, Rebecca, Rotarescu, Rada, Salvary, Ingrid, Sands, Kathy, Sinha, Tapati, Stefanescu, Simina, Sundararaj, Kavitha, Taghipour, Kathy, Taylor, Michelle, Thomson, Michelle, Topliffe, Joanne, Verdolini, Roberto, Wachsmuth, Rachel, Wade, Martin, Wahie, Shyamal, Walsh, Sarah, Walton, Shernaz, Wilcox, Louise, Wright, Andrew, Douroudis, Konstantinos, Ramessur, Ravi, Barbosa, Ines A., Baudry, David, Duckworth, Michael, Angit, Caroline, Capon, Francesca, Chung, Raymond, Curtis, Charles J., Di Meglio, Paola, Goulding, Jonathan M.R., Griffiths, Christopher E.M., Lee, Sang Hyuck, Mahil, Satveer K., Parslew, Richard, Reynolds, Nick J., Shipman, Alexa R., Warren, Richard B., Yiu, Zenas Z.N., Simpson, Michael A., Barker, Jonathan N., Dand, Nick, and Smith, Catherine H.

Published
2022
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50. Between Now and Future Sovereignty: Indigenous Forestry in the Conjuncture.

Author

Simpson, Michael, Atleo, Clifford Gordon, and Braun, Bruce

Subjects
*LOGGING, *OLD growth forests, *CANADIAN history, *HISTORY of colonies, *ECONOMIC history, *ILLEGAL logging
Abstract

The participation of Indigenous nations in the industrial logging of their own territories has received scant attention in academic literature despite the challenges it poses for decolonial critiques of extractive industries and efforts of non‐Indigenous land defenders to build solidarity with Indigenous nations. Taking as a point of departure recent struggles over the logging of old forests on Vancouver Island, in the settler province of British Columbia, and drawing on the political economic history of the island's Nuu‐chah‐nulth peoples, we employ a conjunctural analysis to argue that Indigenous forestry can be understood as the articulation of Indigenous practices of self‐determination (in a context heavily constrained by the colonial past and present) with a set of structural fixes for an industry in crisis. We argue that understanding the present moment of Indigenous forestry as a conjuncture affords an analysis of the tricky conditions that Indigenous communities must imperfectly and strategically navigate to adapt their livelihoods and exercise self‐determination in the colonial present while maintaining possibilities for a decolonised future. It also points to a series of contractions at work in Indigenous forestry which could become disarticulated and rearticulated, potentially opening up wider possibilities for a decolonial future in “BC forests”. [ABSTRACT FROM AUTHOR]

Published
2024
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