Student understanding of rotational and rolling motion concepts

We investigated the common difficulties that students have with concepts related to rotational and rolling motion covered in the introductory physics courses. We compared the performance of calculus- and algebra-based introductory physics students with physics juniors who had learned rotational and rolling motion concepts in an intermediate level mechanics course. Interviews were conducted with six physics juniors and ten introductory students using demonstration-based tasks. We also administered free-response and multiple-choice questions to a large number of students enrolled in introductory physics courses, and interviewed six additional introductory students on the test questions (during the test design phase). All students showed similar difficulties regardless of their background, and higher mathematical sophistication did not seem to help acquire a deeper understanding. We found that some difficulties were due to related difficulties with linear motion, while others were tied specifically to the more intricate nature of rotational and rolling motion.Comment: 23 pages, 3 figures, 2 tables; it includes a multiple-choice test (in Appendix B

Lung Megakaryocytes are Immune Modulatory Cells that Present Antigen to CD4+ T cells.

Although platelets are the cellular mediators of thrombosis, they are also immune cells. Platelets interact both directly and indirectly with immune cells, impacting their activation and differentiation, as well as all phases of the immune response. Megakaryocytes (Mks) are the cell source of circulating platelets, and until recently Mks were typically only considered bone marrow–resident (BM-resident) cells. However, platelet-producing Mks also reside in the lung, and lung Mks express greater levels of immune molecules compared with BM Mks. We therefore sought to define the immune functions of lung Mks. Using single-cell RNA sequencing of BM and lung myeloid-enriched cells, we found that lung Mks, which we term MkL, had gene expression patterns that are similar to antigen-presenting cells. This was confirmed using imaging and conventional flow cytometry. The immune phenotype of Mks was plastic and driven by the tissue immune environment, as evidenced by BM Mks having an MkL-like phenotype under the influence of pathogen receptor challenge and lung-associated immune molecules, such as IL-33. Our in vitro and in vivo assays demonstrated that MkL internalized and processed both antigenic proteins and bacterial pathogens. Furthermore, MkL induced CD4+ T cell activation in an MHC II–dependent manner both in vitro and in vivo. These data indicated that MkL had key immune regulatory roles dictated in part by the tissue environment.pre-print236 K

Exploring Platelet Ido1 Activity in the Pathogenesis of Plasmodium yoelii Uncomplicated Malaria

The malaria causing Plasmodium parasite is a major public health threat. Platelets, critical in immune response and clotting, decrease during malaria (thrombocytopenia), impacting infection control. Despite evidence of platelets\u27 involvement in infection response and malaria progression, the specific molecular mechanisms remain unclear. Malaria triggers a powerful interferon gamma (IFNγ) response, which activates indoleamine 2,3-dioxygenase (IDO1). IDO1 redirects Tryptophan (TRP) away from serotonin production by initiating TRP metabolism towards the kynurenine (KYN) pathway. Our platelet RNA-seq data from P. vivax infected humans and P. yoelii infected mice revealed increased expression of TRP metabolism-related genes, including IDO1. Using the mouse model of uncomplicated malaria, P. yoelii infection (PyNL), we found a post-infection increase in platelet Ido1 expression and a depletion of plasma serotonin, accompanied by increased KYN. These data are recapitulated in mice treated with recombinant IFNγ indicating it as the major immune driver of Ido1 activity. PyNL Infected mice treated with anti-IFNγ had similar metabolic profiles to that of uninfected controls. Ido1-/- mice exhibited a similar metabolic phenotype to PyNL infected mice that received anti-IFNγ treatment. Platelet specific-Ido1-/- mice were less resilient to PyNL infection, emphasizing its impact during malaria. Loss of platelet Ido1 during thrombocytopenia might affect overall immune response

Educational test and measurement an instruction

xiii, 674 p.; 22 cm

Educational test and measurement an introduction/ Nitko

xiii, 674 hal.: ill.: tab.; 24 cm