11,130 research outputs found
Semiclassical stability analysis of a two-photon laser including spatial variation of the cavity field
We investigate the dynamics of a two-photon laser under conditions where the
spatial variation of the cavity field along the cavity axis is important. Main
attention is paid to linear stability analysis and numerical investigation of a
two-photon laser for the Maxwell-Bloch equations. The model assumes pumping to
the upper state of the two-photon transition. We consider the Maxwell-Bloch
equations on the basis of which we study the stability analysis of the steady
state of the system. The system is taken to be contained in a ring-laser
cavity. Asymptotic expansion of the eigenvalue and analytic information are
obtained in some realistic limits, such as very large reflectivity, very small
cavity losses, or very small population relaxation rate. The results are
illustrated with an application to a specific atomic system (Potassium) as an
amplifying medium.Comment: 17 pages, 3 figure
Practical Provably Secure Multi-node Communication
We present a practical and provably-secure multimode communication scheme in
the presence of a passive eavesdropper. The scheme is based on a random
scheduling approach that hides the identity of the transmitter from the
eavesdropper. This random scheduling leads to ambiguity at the eavesdropper
with regard to the origin of the transmitted frame. We present the details of
the technique and analyze it to quantify the secrecy-fairness-overhead
trade-off. Implementation of the scheme over Crossbow Telosb motes, equipped
with CC2420 radio chips, shows that the scheme can achieve significant secrecy
gain with vanishing outage probability. In addition, it has significant
overhead advantage over direct extensions to two-nodes schemes. The technique
also has the advantage of allowing inactive nodes to leverage sleep mode to
further save energy.Comment: Proceedings of the IEEE International Conference on Computing,
Networking and Communications (ICNC 2014
Induced plant resistance as a pest management tactic on piercing sucking insects of sesame crop
Sesame, Sesamum indicum L. is the most oil seed crop of the world and also a major oil seed crop of Egypt. One of the major constraints in its production the damage caused by insect pests, particularly sucking insects which suck the cell sap from leaves, flowers and capsules. Impact of three levels of potassin-F, salicylic acid and combination between them on reduction infestation of Stink bug Nezara viridula L., Mirid bug Creontiades sp., Green peach aphid Myzus persicae (Sulzer), Leafhopper Empoasca lybica de Berg and Whitefly Bemisia tabaci (Gennadius) of sesame crop cultivar Shandawil 3 was carried out during 2010-2011 crop season at Experimental farm, Faculty of Agriculture, Suez Canal University, Ismailia, Egypt. Also, the impacts of potassin-F and salicylic acid on yield production of sesame were studied. Results indicated that percent of reduction of infestation by N. viridula, M. persicae, Creontiades sp., E. lybicae, B. tabaci and phyllody disease were significantly higher at Level 2 (Potassin-F= 2.5 cm/l, Salicylic acid= 0.001 M and Potassin + Salicylic= 2.5 cm/l + 0.001 M) and consequently higher seed yield per plant were obtained
Mott scattering at the interface between a metal and a topological insulator
We compute the spin-active scattering matrix and the local spectrum at the
interface between a metal and a three-dimensional topological band insulator.
We show that there exists a critical incident angle at which complete (100%)
spin flip reflection occurs and the spin rotation angle jumps by . We
discuss the origin of this phenomena, and systematically study the dependence
of spin-flip and spin-conserving scattering amplitudes on the interface
transparency and metal Fermi surface parameters. The interface spectrum
contains a well-defined Dirac cone in the tunneling limit, and smoothly evolves
into a continuum of metal induced gap states for good contacts. We also
investigate the complex band structure of BiSe.Comment: published versio
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