1,582 research outputs found
Pressure Induced Hydration Dynamics of Membranes
Pressure-jump initiated time-resolved x-ray diffraction studies of dynamics
of the hydration of the hexagonal phase in biological membranes show that (i)
the relaxation of the unit cell spacing is non-exponential in time; (ii) the
Bragg peaks shift smoothly to their final positions without significant
broadening or loss in crystalline order. This suggests that the hydration is
not diffusion limited but occurs via a rather homogeneous swelling of the whole
lattice, described by power law kinetics with an exponent .Comment: REVTEX 3, 10 pages,3 figures(available on request),#
Microwave shielding of transparent and conducting single-walled carbon nanotube films
The authors measured the transport properties of single-walled carbon
nanotube (SWCNT) films in the microwave frequency range from 10 MHz to 30 GHz
by using the Corbino reflection technique from temperatures of 20-400 K. Based
on the real and imaginary parts of the microwave conductivity, they calculated
the shielding effectiveness for various film thicknesses. Shielding
effectiveness of 43 dB at 10 MHz and 28 dB at 10 GHz are found for films with
90% optical transmittance, which suggests that SWCNT films are promising as a
type of transparent microwave shielding material. By combining their data with
those from the literature, the conductivity of SWCNT films was established in a
broad frequency range from dc to visible.Comment: 4 pages, 4 figure
Entanglement degradation of a two-mode squeezed vacuum in absorbing and amplifying optical fibers
Applying the recently developed formalism of quantum-state transformation at
absorbing dielectric four-port devices [L.~Kn\"oll, S.~Scheel, E.~Schmidt,
D.-G.~Welsch, and A.V.~Chizhov, Phys. Rev. A {\bf 59}, 4716 (1999)], we
calculate the quantum state of the outgoing modes of a two-mode squeezed vacuum
transmitted through optical fibers of given extinction coefficients. Using the
Peres--Horodecki separability criterion for continuous variable systems
[R.~Simon, Phys. Rev. Lett. {\bf 84}, 2726 (2000)], we compute the maximal
length of transmission of a two-mode squeezed vacuum through an absorbing
system for which the transmitted state is still inseparable. Further, we
calculate the maximal gain for which inseparability can be observed in an
amplifying setup. Finally, we estimate an upper bound of the entanglement
preserved after transmission through an absorbing system. The results show that
the characteristic length of entanglement degradation drastically decreases
with increasing strength of squeezing.Comment: Paper presented at the International Conference on Quantum Optics and
VIII Seminar on Quantum Optics, Raubichi, Belarus, May 28-31, 2000, 11 pages,
LaTeX2e, 4 eps figure
Exploring high temperature magnetic order in CeTi_1-xSc_xGe
Most of magnetic transitions related to Ce ordering are found below
T_ord~12K. Among the few cases exceeding that temperature, two types of
behaviors can be distinguished. One of them is related to the rare cases of Ce
binary compounds formed in BCC structures, with a quartet ground state, whose
degeneracy is reduced by undergoing different types of transitions mostly
structural. The other group shows evidences of itinerant character with the
outstanding example of CeRh_3B_2 showing the highest T_ord=115K. The second
highest ordering temperature has been reported for CeScGe with T_ord=47K, but
the nature of this magnetic state has not been investigated very deeply. In
order to shed more light into this unusual high temperature ordering we studied
the structural, magnetic, transport and thermal properties of CeTi_1-xSc_xGe
alloys in the stability range of the CeScSi-type structure 0.25<x<1 This system
presents a rich variety of magnetic behaviors along this concentration range,
with the magnetic ordering growing from ferromagnetic (FM) T_C~7K up to an
antiferromagnetic (AFM) transition at T_N=47K. The different regions show the
following characteristics: i) on the Ti rich side (0.25<x<0.50) it exhibits a
FM ground state (GS) with large saturation magnetization values M_sat up to
~1.15 mu_B. ii) Around x=0.60, the first crystal electric field excited doublet
starts to contribute to the GS magnetic properties. Furthermore an AFM
component with a connected metamagnetic transition appears. iii) At x=0.65 a
clear change in the GS nature is associated to a critical point above which the
GS properties can be described like for an itinerant system (with decreasing
M_sat) and an effective GS degeneracy N_eff=4. iv) For x>0.65, the magnetic
phase boundary splits into two transitions, with an intermediate phase
presenting incommensurate spin density waves features.Comment: 8 pages, 10 figure
Visualization of Distributed Algorithms Based on Graph Relabelling Systems1 1This work has been supported by the European TMR research network GETGRATS, and by the “Conseil Régional d' Aquitane”.
AbstractIn this paper, we present a uniform approach to simulate and visualize distributed algorithms encoded by graph relabelling systems. In particular, we use the distributed applications of local relabelling rules to automatically display the execution of the whole distributed algorithm. We have developed a Java prototype tool for implementing and visualizing distributed algorithms. We illustrate the different aspects of our framework using various distributed algorithms including election and spanning trees
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