THE BOSTON AREA PHYSICS CALENDAR
Week of Monday, April 20 - April 26, 1997
 
The Boston Area Physics Calendar is published weekly during 
the academic year by the Department of Physics and Astronomy 
at Tufts University.  You may send your announcements by 
e-mail (bapc@tuhepa.phy.tufts.edu) or FAX:(617-627-3878).  
We cannot accept announcements by telephone.  Entries should 
reach us no later than 11:00am on the Monday preceding the week 
of the event. ENTRIES RECEIVED AFTER THE DEADLINE WILL NOT 
BE PUBLISHED.

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Monday, April 21, 1997
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Monday, April 21, 12:15 p.m.

Harvard University
Colloquium 
High Energy Physics Lab. (42 Oxford St.)
3rd Floor Seminar Room
``Spin Physics at RHIC''
MICHAEL J. TANNENBAUM
Brookhaven National Laboratory


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Monday, April 21, 4:30 p.m.

Brown University
Colloquium 
Barus & Holley Building, Room 168
``Biomembrane Dynamics Revealed by Optical Tweezers''
PROFESSOR PHIL NELSON
University of Pennsylvania
Refreshments will be served at 4:00 p.m.


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Monday, April 21, 4:30 p.m.

Harvard University
Colloquium 
Jefferson Building, Room 250
``Localization and Population Biology''
PROFESSOR DAVID R. NELSON
Harvard University
Tea will be served in Jefferson 461 at 4:00 p.m.


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Tuesday, April 22, 1997
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Tuesday, April 22, 12:00 p.m.

Harvard University
Condensed Matter Theory Seminar 
Pierce 100F
``Directed Quantum Chaos''
KONSTANTIN EFETOV
MPI Stuttgart 


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Wednesday, April 23, 1997
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Wednesday, April 23, 4:30 p.m.

Harvard University
Joint Theory Seminar 
Jefferson 256
``Common Sense in String Theory:
Kosterlitz--Thouless Phase Transitions on Random Surfaces''
DR. ANDREI MATYTSIN
Massachusetts Institute of Technology
Refreshments will be served in Lyman 330 at 4:00 p.m.


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Thursday, April 24, 1997
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Thursday, April 24, 12:00 p.m.

Harvard University
Condensed Matter Theory Seminar 
Pierce 100F
``Local Electronic Structure of Defects in Superconductors''
MICHAEL FLATTE
 University of Iowa 


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Thursday, April 24, 12:30 p.m.

Boston University
Biophysics/Soft Condensed Matter Seminar 

Metcalf Science and Engineering Bldg.
590 Commonwealth Ave., Room 352
``Mean-Field Models of Dynamic Wetting and Thermocapillary Flows''
 
Abstract:
 
  Understanding and predicting interfacial wetting dynamics and
thermocapillary flows is crucial for controlling many important
industrial processes. Classical models of these phenomena are based on
macroscopic equations of continuum mechanics and irreversible
thermodynamics, with interfacial properties manifested in boundary
conditions and constitutive relations defined at infinitesimally thin
Gibbsian surfaces. This approach suffers from proliferation of
phenomenological parameters and constitutive relations, and from
inconsistencies and arbitrariness in the choice of the boundary
conditions at the solid-fluid interface.
 
   In reality, interfacial structure, deformation and flows vary over
regions of finite width, and are complicated functions of the chemical
composition, and of the nature and strength of the intermolecular
interactions. Interfacial dynamics also affects (and is sensitive to)
hydrodynamic stresses driven by contact with external species, momentum
and heat reservoirs. Proper description of the structure and dynamics of
moving interfaces on micro-, meso-, and even macro-scopic scales,
requires methods based on nonequilibrium statistical mechanics. When
used in conjunction with a local mean-field approximation, these lead to
effective computational algorithms that depend on a small number of
molecular parameters, eliminate the need for assuming phenomenological
constitutive relations for each of the bulk and interfacial regions, and
to a transparent choice of the boundary conditions at the solid-fluid
interface.
 
   In my talk I will describe our recent work on developing such
methods, including both isothermal and nonisothermal versions of
convective-diffusive lattice-gas models for simple fluids, extension of
the same method to viscoelastic fluids, and its possible off-lattice
generalizations. The usefulness of these methods will be illustrated by
application to a number of dynamic wetting and thermocapillary flow
phenomena. The results  will be compared to those arising from other
modeling methods, and to experimental observations.
 
DR. YITZHAK SHNIDMAN
 Eastman Kodak Company, Rochester, NY 


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Thursday, April 24, 12:30 p.m.

Northeastern University
Colloquium 
335 New Classroom Building
``Teaching and Learning Using the Web''
JOHN VENABLES
Department of Physcis and Chemistry
Arizona State University
School of Chemistry, Physics and Environmental Sciences, 
University of Sussex, UK 


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Thursday, April 24, 1:30 p.m.

Harvard University
Materials Science Seminar 
McKay Laboratory 402
``Surface Instability and Material Failure in a Stressed
Film/Substrate System''
DR. CHENG-HSIN CHIU
Division of Engineering
Brown University 


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Thursday, April 24, 4:00 p.m.

Clark University
Colloquium 
Sackler Science Complex, Room N-105
``Organic Magnets and Superconductors: Over a Muon's Dead Body''
DR. S. J. BLUNDELL
Clarendon Laboratory
Oxford University 


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Thursday, April 24, 4:00 p.m.

Harvard-Smithsonian Center for Astrophysics
Scientific Colloquium 
60 Garden Street (Phillips Auditorium)
``Pulsar Death at An Advanced Age''
 
Abstract:
 
I briefly review the phenomenology of rotation powered
pulsars' (RPPs') photon emission, with emphasis on the evidence that
the magnetic field has a locally dipolar form at low altitude.
I use the observations to motivate the ``classical'' picture
of pulsar radio radiation being a searchlight beam emitted by
relativstic particles moving parallel to dipolar magnetic field
lines. I outline the basic electrodynamics
and particle acceleration characteristics of these stars' magnetic
polar regions.  I review the result that the general relativistic dragging of
inertial frames increases the available accelerating voltage
by roughly an order of magnitude, compared to previous estimates.
This surprising result occurs because the polarization electric
field caused by the accelerated particles cancels the vacuum electric
field, to which the general relativistic effects are a small correction.
I then review the association of pair creation by the gamma rays
 emitted by the accelerated charges with the occurrence of radio
emission, as evidenced by whether or not the theory of pair creation
encompasses all the known pulsars, with the conclusion that
previous theories have associated pair creation with radio emission
only through hypothesizing artificial complexity to the surface
magnetic field which is not in accord with the evidence for the
dipolar character of the low altitude magnetic field.  I then
show that mild offsets of the dipole's center from the stellar,
which ARE consistent with the observations of pulse width and
polarization structure, causes substantial general relativistic
bending of gamma rays' orbits, which in turn increases the opacity
for pair creation.  This effect, combined with the general relativistically
induced increase in the accelerating potential, allows polar cap pair
creation theory to cover all the known pulsars for the first time.
 
I conclude with a brief discussion of several consequences of the
new theory for pulsar radio and X-ray emission which are under development.
 
DR. JONATHAN W. ARONS
Astronomy Department
University of California
Berkeley, California 
Tea will be served at 3:30 p.m.


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Thursday, April 24, 4:15 p.m.

Massachusetts Institute of Technology
Colloquium 
MIT Room 10-250
``Positron Production by Laser Light''
KIRK T. MC DONALD
Princeton University 


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Thursday, April 24, 4:30 p.m.

Brown University
Condensed Matter Seminar 
Barus & Holley Building
Room 751
``Quantum Dots''
DR. NED WINGREEN
NEC Laboratories 


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Friday, April 25, 1997
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Friday, April 25, 4:00 p.m.

Harvard University Division of Engineering and Applied Sciences
Condensed Matter Seminar 
Pierce Hall, Room 209
``Atomic Processes in Epitaxial Growth - What Does a Physicist Want
to Know?''
 
Abstract:
 
In the last few years, the study of atomic processes at surfaces has opened
up enormously, by the development of a whole range of new techniques for
examining surfaces on a microscopic scale. Much of the technological 'push'
for this work has come from the increasing use of epitaxial thin films in
semiconducting and magnetic devices and the need to understand the growth
processes at the atomic level. Faced with this level of experimental detail,
the physicist is posed some interesting challenges. Can the detail be
'explained' without merely resorting to parameter fitting?  How many parameters 
can a good theory support?   Can we relate experimental numbers to a priori theory? 
These questions will be illustrated with recent experiment-theory comparisons 
on metal-metal and metal-semiconductor growth, and on adsorption systems; 
the opportunity for theorists to hone their skills on these systems will 
be emphasised.
 
JOHN A. VENABLES
Department of Physics and Astronomy, Arizona State University,
School of Chemistry, Physics and Environmental Sciences, University of Sussex

Refreshments will be served in the Brooks Room following the seminar.
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A Friendly Reminder:

The Deadline for the April 27-May 3, 1997 Issue is:

MONDAY, April 21, 1997 at 11:00 a.m.

NO ENTRIES WILL BE ACCEPTED
AFTER THE DEADLINE.



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