453 research outputs found

    Extending smooth cyclic group actions on the Poincaré homology sphere

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    Cyclic branched coverings of Brieskorn spheres bounding acyclic 4-manifolds

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    We show that standard cyclic actions on Brieskorn homology 3-spheres with non-empty fixed set do not extend smoothly to any contractible smooth 4-manifold it may bound. The quotient of any such extension would be an acyclic 44-manifold with boundary a related Brieskorn homology sphere. We briefly discuss well known invariants of homology spheres that obstruct acyclic bounding 4-manifolds, and then use a method based on equivariant Yang-Mills moduli spaces to rule out extensions of the actions

    Mathematical Models for Estimating the Risk of vCJD Transmission

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    We present two different simple models for vCJD transmission by blood transfusion. Both models indicate that transfusions alone are unlikely to cause more than a few infections, unless the number of primary cases increases. To improve our models, future work should pursue data collection, empirical estimation of the model parameters, and examination of the underlying assumptions of our frameworks. Further improvements could also include examining susceptibility to vCJD infection by age group and iatrogenic infections introduced through surgical instruments. Regarding the latter, it may be worthwhile to conduct experiments to quantify the transmission of prions from an infected surgical instrument after repeated sterilization procedures

    Quantifying the impact of Covid-19 on the energy consumption in the low-income housing in Greater London

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    Covid-19 has caused great challenges to the energy sector, particularly in residential buildings with low-income households. This study investigates the impact of the confinement measures due to the Covid-19 outbreak on the energy demand of seven residential archetype buildings in Greater London. Three levels of confinement for occupant schedules are proposed and compared with the base case before Covid-19. The archetypes, their boundary conditions, and input parameters are set up according to statistics from English Housing Survey (EHS) sample data for low-income housing. The base case scenario (normal life without confinement measures) is validated against the measured data energy consumption from the National Energy Efficiency Data-Framework (NEED) statistics. The results show that electricity consumption is significantly lower than that for heating and hot water for all the archetypes. By comparing the base case scenario with the full Covid-19 lockdown scenario, the results indicate that heating and hot water consumption (kWh) for all the residential archetypes increases, on average, by 10%, and total electricity demand (kWh) increases by 13%. The study highlights the importance of introducing detailed occupancy profiles in multi-zone building energy simulation models during a pandemic that leads to a greater shift towards home working, which may increase the risk of fuel poverty in low-income housing

    A case of pelvic peritoneal damage by laparoscopy instruments revealed under scanning electron microscope (SEM)

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    Introduction: The role of peritoneal membrane in human has been known in transport of fluids and electrolytes, host defense and reduce friction between bowels and other organs for a long time. This serosal layer consists of a single layer of mesothelial cells resting on basement membrane and submesothelial connective tissue with cell populations and structural proteins. In last decades, human pelvic peritoneum has been studied by using scanning electron microscopy in many conditions to diagnose the diseases especially in endometriosis, chronic pelvic pain and etc. In this study, microstructural changes caused by the surgeon due to unintentionally technical problems in tissue dissections is reported. This article presents unintentionally ultrastructural changes on the pelvic peritoneum during laparoscopic surgery by instruments that can lead to errors in diagnosis and understanding of the disease process for pathologist Case presentation: Two pieces of involved peritoneal tissues with size of 7�7 mm and two pieces of apparently normal peritoneum were evaluated by scanning electron microscopy in a patient with chronic pelvic pain and suspected to endometriosis. Conclusion: According to inadvertent damage of laparoscopic instruments to evaluate fine tissues such as peritoneum, this very simple but important tip should be noted during laparoscopic peritoneal tissue dissections for diagnostic and ultrastructural investigations. © 2016, Canadian Medical Association. All rights reserved

    Quantifying the impact of Covid-19 on the energy consumption in the low-income housing in Greater London

    Get PDF
    Covid-19 has caused great challenges to the energy sector, particularly in residential buildings with low-income households. This study investigates the impact of the confinement measures due to the Covid-19 outbreak on the energy demand of seven residential archetype buildings in Greater London. Three levels of confinement for occupant schedules are proposed and compared with the base case before Covid-19. The archetypes, their boundary conditions, and input parameters are set up according to statistics from English Housing Survey (EHS) sample data for low-income housing. The base case scenario (normal life without confinement measures) is validated against the measured data energy consumption from the National Energy Efficiency Data-Framework (NEED) statistics. The results show that electricity consumption is significantly lower than that for heating and hot water for all the archetypes. By comparing the base case scenario with the full Covid-19 lockdown scenario, the results indicate that heating and hot water consumption (kWh) for all the residential archetypes increases, on average, by 10%, and total electricity demand (kWh) increases by 13%. The study highlights the importance of introducing detailed occupancy profiles in multi-zone building energy simulation models during a pandemic that leads to a greater shift towards home working, which may increase the risk of fuel poverty in low-income housing.Peer reviewe
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