36,049 research outputs found
Can re-entrance be observed in force induced transitions?
A large conformational change in the reaction co-ordinate and the role of the
solvent in the formation of base-pairing are combined to settle a long standing
issue {\it i.e.} prediction of re-entrance in the force induced transition of
DNA. A direct way to observe the re-entrance, i.e a strand goes to the closed
state from the open state and again to the open state with temperature, appears
difficult to be achieved in the laboratory. An experimental protocol (in direct
way) in the constant force ensemble is being proposed for the first time that
will enable the observation of the re-entrance behavior in the
force-temperature plane. Our exact results for small oligonucleotide that forms
a hairpin structure provide the evidence that re-entrance can be observed.Comment: 12 pages and 5 figures (RevTex4). Accepted in Europhys Lett. (2009
Plasmon Annihilation into Kaluza-Klein Graviton: New Astrophysical Constraints on Large Extra Dimensions
In large extra dimensional Kaluza-Klein (KK) scenario, where the usual
Standard Model (SM) matter is confined to a 3+1-dimensional hypersurface called
the 3-brane and gravity can propagate to the bulk (D=4+d, d being the number of
extra spatial dimensions), the light graviton KK modes can be produced inside
the supernova core due to the usual nucleon-nucleon bremstrahlung,
electron-positron and photon-photon annihilations. This photon inside the
supernova becomes plasmon due to the plasma effect. In this paper, we study the
energy-loss rate of SN 1987A due to the KK gravitons produced from the
plasmon-plasmon annihilation. We find that the SN 1987A cooling rate leads to
the conservative bound > 22.9 TeV and 1.38 TeV for the case of two and
three space-like extra dimensions.Comment: 13 pages, 1 ps figure, text is modified a little bit, conclusion
unchanged, new references are added, version accepted for publication in PR
Equipartition of Current in Parallel Conductors on Cooling Through the Superconducting Transition
Our experiments show that for two or more pieces of a wire, of different
lengths in general, combined in parallel and connected to a dc source, the
current ratio evolves towards unity as the combination is cooled to the
superconducting transition temperature Tc, and remains pinned at that value
below it. This re-distribution of the total current towards equipartition
without external fine tuning is a surprise. It can be physically understood in
terms of a mechanism that involves the flux-flow resistance associated with the
transport current in a wire of type-II superconducting material. It is the fact
that the flux-flow resistance increases with current that drives the current
division towards equipartition.Comment: Revised version of J.Phys. Condens.Matter; vol. 18(2006) L143-L147 14
pages including 3 figures; provided an explanation in terms of the physical
mechanism of flux flow induced resistance that is proportional to the
impressed current. We are adding a simple, physically robust derivation of
our equipartition without taking resort to the minimum dissipation principl
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