Marchetti gave invited talk at Winter Conference February 5, 2018 • by Michelle Lissner Cristina Marchetti gave an invited talk at the Aspen Winter Conference Fundamental Problems in Active Matter, held at the Aspen Center for Physics Jan 29-Feb 2, 2018 http://fpam.msc.univ-paris-diderot.fr Marchetti’s talk titled, Rigidity and flocking transitions in dense tissues