Managing fisheries in a changing climate

No need to wait for more information: industrialized fishing is already wiping out stocks

Moving Embedded Solitons

The first theoretical results are reported predicting {\em moving} solitons residing inside ({\it embedded} into) the continuous spectrum of radiation modes. The model taken is a Bragg-grating medium with Kerr nonlinearity and additional second-derivative (wave) terms. The moving embedded solitons (ESs) are doubly isolated (of codimension 2), but, nevertheless, structurally stable. Like quiescent ESs, moving ESs are argued to be stable to linear approximation, and {\it semi}-stable nonlinearly. Estimates show that moving ESs may be experimentally observed as $\sim$10 fs pulses with velocity $\leq 1/10$th that of light.Comment: 9 pages 2 figure

Embedded Solitons in a Three-Wave System

We report a rich spectrum of isolated solitons residing inside ({\it embedded } into) the continuous radiation spectrum in a simple model of three-wave spatial interaction in a second-harmonic-generating planar optical waveguide equipped with a quasi-one-dimensional Bragg grating. An infinite sequence of fundamental embedded solitons are found, which differ by the number of internal oscillations. Branches of these zero-walkoff spatial solitons give rise, through bifurcations, to several secondary branches of walking solitons. The structure of the bifurcating branches suggests a multistable configuration of spatial optical solitons, which may find straightforward applications for all-optical switching.Comment: 5 pages 5 figures. To appear in Phys Rev

Relaxation effect and radiative corrections in many-electron atoms

We illuminate the importance of a self-consistent many-body treatment in calculations of vacuum polarization corrections to the energies of atomic orbitals in many-electron atoms. Including vacuum polarization in the atomic Hamiltonian causes a substantial re-adjustment (relaxation) of the electrostatic self-consistent field. The induced change in the electrostatic energies is substantial for states with the orbital angular momentum l &;gt; 0. For such orbitals, the relaxation mechanism determines the sign and even the order of magnitude of the total vacuum polarization correction. This relaxation mechanism is illustrated with numerical results for the Cs atom

DOES THE CFTC COMMITMENTS OF TRADERS REPORT CONTAIN USEFUL INFORMATION?

The Commodity Futures Trading Commission's Commitments of Traders data are examined. Non-commercial positions are thought to contain the least amount of measurement error. Although non-commercials comprise a relatively small percent of the tested markets' open interest (10% to 22%), they have the most volatile net positions. The data demonstrates a statistically (positive) negative contemporaneous correlation between net positions held by (non) commercials and market returns. However, traders' net positions do not lead (Granger cause) market returns. In fact, returns lead traders' net positions. Positive returns result in an (increase) decrease in (non) commercials net positions the following week. The findings suggest that prior empirical results, which make assumptions about traders' positions not changing over a reporting interval, may be biased toward reflecting the contemporaneous position-return correlations reported in this research.Commitments of Traders, commercial traders, non-commercial traders, funds, Marketing,