Physics Tip Sheet #11 - May 1, 2002
Contact: David Harris
harris@aps.org
301-209-3238
American Physical Society
1) Experimental control of heart rhythms
G. Hall and D. Gauthier
Physical Review Letters (Print issue: May 13, 2002)
Alternans is a periodic heart rhythm that can cause fibrillation and heart attacks. An experimental study in bullfrog hearts showed that alternans was reliably suppressed and prevented from re-occurring. Electrical activity in the heart was monitored and a feedback cycle applied small electrical impulses to the heart. The authors suggest that a modification of this procedure may be able to maintain normal heart function in humans.
Journal article: http://link.aps.org/abstract/PRL/v88/e198102
2) How drops drip
A. D'Innocenzo, F. Paladini, and L. Renna
Physical Review E (Print issue: May 2002)
Understanding dripping has engineering applications from control of ink-jet printers to biochip arrayers. Dripping shows a wide variety of characteristics from periodic to chaotic but has never been clearly connected with the physical properties of a system. A set of experiments explores the connections between nozzle sizes, nozzle shapes, flow rates and dripping patterns. The researchers found that for large nozzles, the dripping patterns are mainly dependent on flow rates. For small nozzles, the patterns depend on the shape of the nozzle such as whether it is flat or beveled. By reducing the diameter and wall thickness of nozzles, satellite drops (small drops accompanying larger drops) are practically eliminated.
Journal article: http://link.aps.org/abstract/PRE/v65/e056208
3) Hydrogen at extremely high pressures
M. Knudson, R. Cauble
APS April Meeting/Physics News Update
Hydrogen at extremely high pressures, upwards of a million times that on the Earth's surface, can now be produced in physics laboratories. Understanding hydrogen's behavior under such extreme conditions answers questions about the interior of Jupiter, provides coveted information on designing optimal fuel pellets for fusion energy, and yields information on aging nuclear weapons without having to test them.
Physics News Update: http://www.aip.org/enews/physnews/2002/split/587-2.html
4) Entanglement from noise
M. Plenio and S. Huelga
Physical Review Letters (Print issue: May 13, 2002)
Quantum information processing usually takes great pains to avoid external noise destroying sought-after effects. This study shows how random "white" noise can actually create entanglement. In an example system, an atom was stored in intersecting optical cavities and bombarded with noisy light. Entangled light then built up in the cavities.
Journal article: http://link.aps.org/abstract/PRL/v88/e197901
5) Fractional atoms
J. Ruostekoski, G. Dunne, and J. Javanainen
Physical Review Focus/Physical Review Letters (Print issue: May 6, 2002)
Atoms may soon be available in fractional form. When specially prepared atoms are lined up in a one-dimensional array, the number of atoms at one of the sites can be fractional. Fractional electrons are well known but this is the first proposal for making fractional atoms. The system uses a Fermi-Dirac gas, analogous to a Bose-Einstein condensate but for different types of atoms.
Physical Review Focus: http://focus.aps.org/v9/st21.html
Journal article: http://link.aps.org/abstract/PRL/v88/e180401
6) Negative mobility for single classical particles
R. Eichhorn, P. Reimann, and P. Hdnggi
Physical Review Letters (Print issue: May 13, 2002)
Push on something and it generally moves in the same direction. However, it is possible for some systems to move in the opposite direction to which they are pushed. In the past, these systems have been asymmetric and the effect only works for forces in some directions. In other cases, the negative mobility is due to quantum mechanics or collective effects. A new analysis shows that single classical particles can exhibit negative mobility in non-equilibrium systems. The example given involves a particle being jostled by others in Brownian motion while in a set of "traps" that are "stickier" for greater forces. The authors claim that this behavior may occur in a wide variety of situations.
Journal article: http://link.aps.org/abstract/PRL/v88/e190601
7) The cyclic universe - an informal introduction
P. Steinhardt, N. Turok
arXiv preprint server
With the recent attention to their cyclic universe model, the authors have just released a less math-intensive description of their theory in which the Universe undergoes an endless sequence of epochs which begin with a `big bang' and end in a `big crunch.'
Preprint: http://www.arxiv.org/abs/astro-ph/0204479
Journal article: http://www.sciencemag.org/cgi/content/abstract/1070462v1
Papers from the Physical Review series of journals are available pre-publication to journalists on request.
For media assistance with these or other physics stories, contact:
David Harris
Head of Media Relations
American Physical Society
Ph: +1 301 209 3238
Fax: +1 301 209 3264
Email: harris@aps.org
