Error Probability of DPSK Signals with Intrachannel Four-Wave-Mixing in Highly Dispersive Transmission Systems

A semi-analytical method evaluates the error probability of DPSK signals with intrachannel four-wave-mixing (IFWM) in a highly dispersive fiber link with strong pulse overlap. Depending on initial pulse width, the mean nonlinear phase shift of the system can be from 1 to 2 rad for signal-to-noise ratio (SNR) penalty less than 1 dB. An approximated empirical formula, valid for penalty less than 2 dB, uses the variance of the differential phase of the ghost pulses to estimate the penalty.Comment: 3 pages, 3 figure

Sobolev inequalities for (0,q)(0,q) forms on CR manifolds of finite type

Let $M^{2n+1}$ ($n \geq 2$) be a compact pseudoconvex CR manifold of finite commutator type whose \dbarb has closed range in $L^2$ and whose Levi form has comparable eigenvalues. We prove a sharp $L^1$ Sobolev inequality for the \dbarb complex for $(0,q)$ forms when $q \ne 1$ nor $n-1$. We also prove an analogous $L^1$ inequality when $M$ satisfies condition $Y(q)$. The main technical ingredient is a new kind of $L^1$ duality inequality for vector fields that satisfy Hormander's condition.Comment: to appear in Math. Res. Lett

Performance of DPSK Signals with Quadratic Phase Noise

Nonlinear phase noise induced by the interaction of fiber Kerr effect and amplifier noises is a quadratic function of the electric field. When the dependence between the additive Gaussian noise and the quadratic phase noise is taking into account, the joint statistics of quadratic phase noise and additive Gaussian noise is derived analytically. When the error probability for differential phase-shift keying (DPSK) signals is evaluated, depending on the number of fiber spans, the signal-to-noise ratio (SNR) penalty is increased by up to 0.23 dB due to the dependence between the Gaussian noise and the quadratic phase noise.Comment: 15 pages, 2 figure

Exact Model for Mode-Dependent Gains and Losses in Multimode Fiber

In the strong mode coupling regime, the model for mode-dependent gains and losses (collectively referred as MDL) of a multimode fiber is extended to the region with large MDL. The MDL is found to have the same statistical properties as the eigenvalues of the summation of two matrices. The first matrix is a random Gaussian matrix with standard deviation proportional to the accumulated MDL. The other matrix is a deterministic matrix with uniform eigenvalues proportional to the square of the accumulated MDL. The results are analytically correct for fibers with two or large number of modes, and also numerically verified for other cases.Comment: 7 pages, 2 figures, 2 table

The politics of evidence: ‘Doing nothing’ about LGBT health inequities by the WHO

How is ‘nothing’ produced and justified, and how is it functioning? Here, I will take a multilateral debate in the World Health Organisation (WHO) over the issues regarding health inequities experienced by sexual and gender minorities as an example. This article asks what national delegates really mean when they blame on the lack of evidence? Observing the debates in the WHO and elsewhere, what certain national governments have been doing is to avoid – by not making anything happen – a potential formulation of future international pressure through global health policymaking and its normative discourse. Through deconstructing the discourse of a ‘lack of evidence’, I identify the socio-political functions of ignorance and ignoring. That is, they did nothing, not because they didn’t understand and care. Quite on the contrary, it was because they cared and knew too well that health is always political, and yet, it is not just the politics concerning knowledge production and media representation; it is also international politics

A Folk Tale of a Butterfly

This folk tale describes how a butterfly and worm respect one anotherThis collection of 77 audio files focuses on weddings and weddings speeches but also contains: folk tales, folk songs, riddles, tongue twisters, and local history from Bang smad Village and Ri sne Village, Bang smad Township, Nyag rong CountyWorld Oral Literature Projec