Dynamic analysis and control of an antagonistically actuated tensegrity mechanism

International audienceThis paper analyses the dynamics of an antagonistically ac-tuated tensegrity mechanism. The mechanism is subject to gravity effects , which produce both stable and unstable equilibrium configurations. The workspace is shown to be not necessarily connected and its size depends on both the geometric, spring and actuator parameters of the mechanism. The antagonistic actuation forces, which are bounded, enable controlling both the stiffness and the position within certain limits. A computed torque control law is applied and simulations show interesting behaviors of the mechanism when the desired motion makes the mechanism jump between two connected components of the workspace

Cytomegalovirus CC Chemokine Promotes Immune Cell Migration

Cytomegaloviruses manipulate the host chemokine/receptor axis by altering cellular chemokine expression and by encoding multiple chemokines and chemokine receptors. Similar to human cytomegalovirus (HCMV), rat cytomegalovirus (RCMV) encodes multiple CC chemokine-analogous proteins, including r129 (HCMV UL128 homologue) and r131 (HCMV UL130 and MCMV m129/130 homologues). Although these proteins play a role in CMV entry, their function as chemotactic cytokines remains unknown. In the current study, we examined the role of the RCMV chemokine r129 in promoting cellular migration and in accelerating transplant vascular sclerosis (TVS) in our rat heart transplant model. We determined that r129 protein is released into culture supernatants of infected cells and is expressed with late viral gene kinetics during RCMV infection and highly expressed in heart and salivary glands during in vivo rat infections. Using the recombinant r129 protein, we demonstrated that r129 induces migration of lymphocytes isolated from rat peripheral blood, spleen, and bone marrow and from a rat macrophage cell line. Using antibody-mediated cell sorting of rat splenocytes, we demonstrated that r129 induces migration of naïve/central memory CD4(+) T cells. Through ligand-binding assays, we determined that r129 binds rat CC chemokine receptors CCR3, CCR4, CCR5, and CCR7. In addition, mutational analyses identified functional domains of r129 resulting in recombinant proteins that fail to induce migration (r129-ΔNT and -C31A) or alter the chemotactic ability of the chemokine (r129-F43A). Two of the mutant proteins (r129-C31A and -ΔNT) also act as dominant negatives by inhibiting migration induced by wild-type r129. Furthermore, infection of rat heart transplant recipients with RCMV containing the r129-ΔNT mutation prevented CMV-induced acceleration of TVS. Together our findings indicate that RCMV r129 is highly chemotactic, which has important implications during RCMV infection and reactivation and acceleration of TVS

Re-odorization, disease, and emotion in mid-Nineteenth-century England

This article argues that smell's place in nineteenth-century medicine and public health was distinctly ambiguous. Standard narratives in the history of smell argue that smell became less important in this period whilst also arguing that urban spaces were deodorized. The causal motor for the latter shift is medical theories about odour and miasma. By contrast, this article argues that sanitary practices of circulation, ventilation, and disinfection proceeded despite, not because of, medical attitudes to smell. Surgeons and physicians argued that odours were no indicator of disease causing matter and distrusted the use of smell because of its subjective qualities and resistance to linguistic definition. Yet these qualities made smell all the more powerful in sanitary literature, where it was used to generate a powerful emotional effect on readers. Histories of smell need to attend not just to deodorization but re-odorization; the disjuncture between practices of smelling and their textual or visual representation; and chronologies that track the shelving and re-deploying of ways of sensing in different times, places, and communities rather than tracking the de novo emergence of a modern Western sensorium. In mid-nineteenth-century England, smell retained its power, but that power now came from its rhetorical rather than epistemological force