BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//talks.cam.ac.uk//v3//EN
BEGIN:VTIMEZONE
TZID:Europe/London
BEGIN:DAYLIGHT
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
TZNAME:BST
DTSTART:19700329T010000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
TZNAME:GMT
DTSTART:19701025T020000
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Twisted paths in Euclidean groups: Keeping track o
f total orientation while traversing DNA - Chirikj
ian\, G S (Johns Hopkins University)
DTSTART;TZID=Europe/London:20120905T113000
DTEND;TZID=Europe/London:20120905T115000
UID:TALK39540AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/39540
DESCRIPTION:This talk introduces a new mathematical structure
for modeling global twist in DNA. The relative rig
id-body motion between reference frames attached e
ither to a backbone curve\, bi-rods\, or individua
l bases in DNA\, can be described well using eleme
nts of the Euclidean motion group\, SE(n). However
\, the group law for Euclidean motions does not ke
ep track of overall twist. In the planar case\, th
e universal covering group of SE(2) identifies ori
entation angle as a quantity on the real line rath
er than on the circle\, and hence keeps track of `
`global'' rotations (not modulo 360 degrees). Howe
ver\, in the three-dimensional case\, no such stru
cture exists since the the orientational part of t
he universal cover of SE(3) can be identified with
the quaternion sphere. In this talk a new mathema
tical structure for ``adding'' framed curves and e
xtracting global twist is present. Though reminisc
ent of the group operation in braid theory and in
homotopy theory\, this structure is distinctly dif
ferent\, as it is geometric in nature\, rather tha
n topological. The motivation for this mathematica
l structure and its applications to DNA conformati
on will be presented.\n
LOCATION:Seminar Room 1\, Newton Institute
CONTACT:Mustapha Amrani
END:VEVENT
END:VCALENDAR