Rotational Mobility Analysis of the 3-RFR Class of Spherical Parallel Robots

none4noSpherical parallel manipulators (SPMs) are used to orient a tool in the space with three degrees of freedom exploiting the strengths of a multi-limb architecture. On the other hand, the performance of parallel kinematics machines (PKMs) is often affected by the occurrence of different kinds of singular configurations. The paper aims at characterizing a class of SPMs for which all singularities come to coincide and a single expression is able to describe all the singular configurations of the machines. The study is focused on a class of SPMs with 3-RFR topology (Revolute-Planar-Revolute pairs for each of the three limbs) addressing the mobility and singularity analysis by means of polynomial decomposition and screw theory. The neatness of the equations that are worked out, expressed in a robust formulation based on rotation invariants, allows a straightforward planning of singularity free tasks and simplifies the synthesis of dexterous machines.openCorinaldi, David; Carbonari, Luca; Palpacelli, Matteo-Claudio; Callegari, MassimoCorinaldi, David; Carbonari, Luca; Palpacelli, Matteo-Claudio; Callegari, Massim

Risk of Arterial and Venous Thrombotic Events Among Patients with COVID-19: A Multi-National Collaboration of Regulatory Agencies from Canada, Europe, and United States

Vincent Lo Re III,1,2,* Noelle M Cocoros,3,4,* Rebecca A Hubbard,2 Sarah K Dutcher,5 Craig W Newcomb,2 John G Connolly,3,4 Silvia Perez-Vilar,5 Dena M Carbonari,2 Maria E Kempner,3,4 José J Hernández-Muñoz,5 Andrew B Petrone,3,4 Allyson M Pishko,6 Meighan E Rogers Driscoll,3,4 James T Brash,7 Sean Burnett,8,9 Catherine Cohet,10 Matthew Dahl,8,11 Terese A DeFor,12 Antonella Delmestri,13 Djeneba Audrey Djibo,14 Talita Duarte-Salles,15,16 Laura B Harrington,17 Melissa Kampman,18 Jennifer L Kuntz,19 Xavier Kurz,10 Núria Mercadé-Besora,15 Pamala A Pawloski,12 Peter R Rijnbeek,16 Sarah Seager,7 Claudia A Steiner,20,21 Katia Verhamme,16 Fangyun Wu,8,22 Yunping Zhou,23 Edward Burn,13 J Michael Paterson,8,22,* Daniel Prieto-Alhambra13,16,* 1Division of Infectious Diseases, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; 2Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; 3Department of Population Medicine, Harvard Medical School, Boston, MA, USA; 4Harvard Pilgrim Healthcare Institute, Boston, MA, USA; 5Office of Surveillance and Epidemiology, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, MD, USA; 6Division of Hematology and Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; 7IQVIA, Real World Solutions, Brighton, UK; 8Canadian Network for Observational Drug Effect Studies (CNODES), Toronto, Ontario, Canada; 9Therapeutics Initiative, University of British Columbia, Vancouver, British Columbia, Canada; 10Data Analytics and Methods Task Force, European Medicines Agency, Amsterdam, Netherlands; 11Manitoba Centre for Health Policy, University of Manitoba, Winnipeg, Manitoba, Canada; 12HealthPartners Institute, Bloomington, MN, USA; 13Pharmaco- and Device Epidemiology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford, Oxford, UK; 14CVS Health, Blue Bell, PA, USA; 15Fundació Institut Universitari per a la recerca a l’Atenció Primària de Salut Jordi Gol i Gurina (IDIAPJGol), Barcelona, Spain; 16Department of Medical Informatics, Erasmus University Medical Center, Rotterdam, Netherlands; 17Kaiser Permanente Washington Health Research Institute, Seattle, WA, USA; 18Health Canada, Ottawa, Ontario, Canada; 19Kaiser Permanente Northwest Center for Health Research, Portland, OR, USA; 20Kaiser Permanente Colorado Institute for Health Research, Aurora, CO, USA; 21Colorado Permanente Medical Group, Denver, CO, USA; 22ICES, Toronto, Ontario, Canada; 23Humana Healthcare Research, Inc., Louisville, KY, USA*These authors contributed equally to this workCorrespondence: Vincent Lo Re III, Division of Infectious Diseases, Department of Medicine, Division of Epidemiology, Department of Biostatistics, Epidemiology, and Informatics, Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, 836 Blockley Hall, 423 Guardian Drive, Philadelphia, PA, 19104-6021, USA, Fax +1 215 573 5315, Email [email protected]: Few studies have examined how the absolute risk of thromboembolism with COVID-19 has evolved over time across different countries. Researchers from the European Medicines Agency, Health Canada, and the United States (US) Food and Drug Administration established a collaboration to evaluate the absolute risk of arterial (ATE) and venous thromboembolism (VTE) in the 90 days after diagnosis of COVID-19 in the ambulatory (eg, outpatient, emergency department, nursing facility) setting from seven countries across North America (Canada, US) and Europe (England, Germany, Italy, Netherlands, and Spain) within periods before and during COVID-19 vaccine availability.Patients and Methods: We conducted cohort studies of patients initially diagnosed with COVID-19 in the ambulatory setting from the seven specified countries. Patients were followed for 90 days after COVID-19 diagnosis. The primary outcomes were ATE and VTE over 90 days from diagnosis date. We measured country-level estimates of 90-day absolute risk (with 95% confidence intervals) of ATE and VTE.Results: The seven cohorts included 1,061,565 patients initially diagnosed with COVID-19 in the ambulatory setting before COVID-19 vaccines were available (through November 2020). The 90-day absolute risk of ATE during this period ranged from 0.11% (0.09– 0.13%) in Canada to 1.01% (0.97– 1.05%) in the US, and the 90-day absolute risk of VTE ranged from 0.23% (0.21– 0.26%) in Canada to 0.84% (0.80– 0.89%) in England. The seven cohorts included 3,544,062 patients with COVID-19 during vaccine availability (beginning December 2020). The 90-day absolute risk of ATE during this period ranged from 0.06% (0.06– 0.07%) in England to 1.04% (1.01– 1.06%) in the US, and the 90-day absolute risk of VTE ranged from 0.25% (0.24– 0.26%) in England to 1.02% (0.99– 1.04%) in the US.Conclusion: There was heterogeneity by country in 90-day absolute risk of ATE and VTE after ambulatory COVID-19 diagnosis both before and during COVID-19 vaccine availability.Plain Language Summary: Cohort studies of patients diagnosed with COVID-19 in both the ambulatory and hospital settings have suggested that SARS-CoV-2 infection promotes hypercoagulability that could lead to arterial or venous thromboembolism. However, few studies have examined how the risk of thromboembolism with COVID-19 has evolved over time across different countries. A new collaboration was established among the regulatory authorities of Canada, Europe, and the US within the International Coalition of Medicines Regulatory Authorities to evaluate the 90-day risk of both arterial and venous thromboembolism after initial diagnosis of COVID-19 in the ambulatory or hospital setting from seven countries across North America (Canada, US) and Europe (England, Germany, Italy, Netherlands, and Spain) within periods before and during COVID-19 vaccine availability. The study found that there was variability in the risk of both arterial and venous thromboembolism by month across the countries among patients initially diagnosed with COVID-19 in the ambulatory or hospital setting. Differences in the healthcare systems, prevalence of comorbidities in the study cohorts, and approaches to the case definitions of thromboembolism likely contributed to the variability in estimates of thromboembolism risk across the countries.Keywords: COVID-19, ischemic stroke, myocardial infarction, thromboembolism, venous thromboembolis

Electric fields generated by synchronized oscillations of microtubules, centrosomes and chromosomes regulate the dynamics of mitosis and meiosis

<p>Abstract</p> <p>Super-macromolecular complexes play many important roles in eukaryotic cells. Classical structural biological studies focus on their complicated molecular structures, physical interactions and biochemical modifications. Recent advances concerning intracellular electric fields generated by cell organelles and super-macromolecular complexes shed new light on the mechanisms that govern the dynamics of mitosis and meiosis. In this review we synthesize this knowledge to provide an integrated theoretical model of these cellular events. We suggest that the electric fields generated by synchronized oscillation of microtubules, centrosomes, and chromatin fibers facilitate several events during mitosis and meiosis, including centrosome trafficking, chromosome congression in mitosis and synapsis between homologous chromosomes in meiosis. These intracellular electric fields are generated under energy excitation through the synchronized electric oscillations of the dipolar structures of microtubules, centrosomes and chromosomes, three of the super-macromolecular complexes within an animal cell.</p