= table.column(:preview_picture) do |person|
  - if person.preview_picture.present?
    %img.img-responsive.bottom-margin-2{ src: person.preview_picture.image.url(:medium_thumb), alt: person.preview_picture.description, title: person.preview_picture.description }
= table.column :firstname
= table.column :lastname
= table.column :birthdate
= table.timestamps
= table.acts_as_list_actions