University of Copenhagen

About: University of Copenhagen is a education organization based out in Copenhagen, Denmark. It is known for research contribution in the topics: Population & Medicine. The organization has 57645 authors who have published 149740 publications receiving 5903093 citations. The organization is also known as: Copenhagen University & Københavns Universitet.

Overview of Structure and Function of Mammalian Cilia

Abstract: Cilia are membrane-bounded, centriole-derived projections from the cell surface that contain a microtubule cytoskeleton, the ciliary axoneme, surrounded by a ciliary membrane. Axonemes in multicili- ated cells of mammalian epithelia are 9 + 2, possess dynein arms, and are motile. In contrast, single nonmotile 9 + 0 primary cilia are found on epithelial cells, such as those of the kidney tubule, but also on nonepithelial cells, such as chondrocytes, fibroblasts, and neurons. The ciliary membranes of all cilia contain specific receptors and ion channel proteins that initiate signaling pathways controlling motil- ity and/or linking mechanical or chemical stimuli, including sonic hedgehog and growth factors, to intracellular transduction cascades regulating differentiation, migration, and cell growth during devel- opment and in adulthood. Unique motile 9 + 0 cilia, found during development at the embryonic node, determine left-right asymme- try of the body.

Genomics and epidemiology of the P.1 SARS-CoV-2 lineage in Manaus, Brazil.

Abstract: Cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Manaus, Brazil, resurged in late 2020 despite previously high levels of infection. Genome sequencing of viruses sampled in Manaus between November 2020 and January 2021 revealed the emergence and circulation of a novel SARS-CoV-2 variant of concern. Lineage P.1 acquired 17 mutations, including a trio in the spike protein (K417T, E484K, and N501Y) associated with increased binding to the human ACE2 (angiotensin-converting enzyme 2) receptor. Molecular clock analysis shows that P.1 emergence occurred around mid-November 2020 and was preceded by a period of faster molecular evolution. Using a two-category dynamical model that integrates genomic and mortality data, we estimate that P.1 may be 1.7- to 2.4-fold more transmissible and that previous (non-P.1) infection provides 54 to 79% of the protection against infection with P.1 that it provides against non-P.1 lineages. Enhanced global genomic surveillance of variants of concern, which may exhibit increased transmissibility and/or immune evasion, is critical to accelerate pandemic responsiveness.

Current practice in measuring usability: Challenges to usability studies and research

Abstract: How to measure usability is an important question in HCI research and user interface evaluation. We review current practice in measuring usability by categorizing and discussing usability measures from 180 studies published in core HCI journals and proceedings. The discussion distinguish several problems with the measures, including whether they actually measure usability, if they cover usability broadly, how they are reasoned about, and if they meet recommendations on how to measure usability. In many studies, the choice of and reasoning about usability measures fall short of a valid and reliable account of usability as quality-in-use of the user interface being studied. Based on the review, we discuss challenges for studies of usability and for research into how to measure usability. The challenges are to distinguish and empirically compare subjective and objective measures of usability; to focus on developing and employing measures of learning and retention; to study long-term use and usability; to extend measures of satisfaction beyond post-use questionnaires; to validate and standardize the host of subjective satisfaction questionnaires used; to study correlations between usability measures as a means for validation; and to use both micro and macro tasks and corresponding measures of usability. In conclusion, we argue that increased attention to the problems identified and challenges discussed may strengthen studies of usability and usability research.

Biofilm formation by Pseudomonas aeruginosa wild type, flagella and type IV pili mutants

Abstract: Summary Biofilm formation by Gfp-tagged Pseudomonas aeruginosa PAO1 wild type, flagella and type IV pili mutants in flow chambers irrigated with citrate mini- mal medium was characterized by the use of confocal laser scanning microscopy and COMSTAT image anal- ysis. Flagella and type IV pili were not necessary for P. aeruginosa initial attachment or biofilm formation, but the cell appendages had roles in biofilm develop- ment, as wild type, flagella and type IV pili mutants formed biofilms with different structures. Dynamics and selection during biofilm formation were investi- gated by tagging the wild type and flagella/type IV mutants with Yfp and Cfp and performing time-lapse confocal laser scanning microscopy in mixed colour biofilms. The initial microcolony formation occurred by clonal growth, after which wild-type P. aeruginosa bacteria spread over the substratum by means of twitching motility. The wild-type biofilms were dynamic compositions with extensive motility, com- petition and selection occurring during development. Bacterial migration prevented the formation of larger microcolonial structures in the wild-type biofilms. The results are discussed in relation to the current model for P. aeruginosa biofilm development.