Portfolio optimization methods suffer from a catalogue of known problems, mainly due to the facts that pair correlations asset returns are unstable, and extremal risk measures such as maximum drawdown difficult predict non-Gaussianity portfolio returns. \\ In order look at optimal portfolios for arbitrary penalty functions, we construct shapes where is proportional moment $p>2$. The resulting c...

This letter investigates the energy efficiency (EE) scaling law for the broadcasting channels (BC) with many users, in which the non-ideal transmit independent power consumption is taken into account. We first consider the single antenna case with K users, and derive that the EE scales as log2 lnK α when α > 0 and log2 K when α = 0, where α is the normalized transmit independent power. After th...

Based on the minute-by-minute data of the Hang Seng Index in Hong Kong and the analysis of probability distribution and autocorrelations, we find that the index fluctuations for the first few minutes of daily opening show behaviors very different from those of the other times. In particular, the properties of tail distribution, which will show the power law scaling with exponent about −4 or an ...

We measure two-dimensional profiles of collimated microwave beams transmitted through composite wire and split-ring resonator prisms. Prior experiments suggest these structures have a negative index of refraction, though these claims have been questioned. Our 2D measurements demonstrate that transmission obeys Snell's law with a negative index, confirming the refractive nature of this signal an...

We report on the evolution of the X-ray energy spectrum for the black hole candidate (BHC) X-ray transient XTE J1550–564 during the decay of the 2000 outburst. The Rossi X-ray Timing Explorer (RXTE) and Chandra observations span nearly five orders of magnitude in luminosity. The RXTE spectra are dominated by a power-law component and a comparatively weak soft component was also detected for the...

The X-ray afterglows (AGs) of Gamma-Ray Bursts (GRBs) and X-Ray Flashes (XRFs) have, after the fast decline phase of their prompt emission, a temporal behaviour varying between two extremes. A large fraction of these AGs has a ‘canonical’ light curve which, after an initial shallow-decay ‘plateau’ phase, ‘breaks smoothly’ into a fast power-law decline. Very energetic GRBs, contrariwise, appear ...

We discuss the emergent spectra from accreting black holes, considering in particular the case where the accretion is characterized by relativistic bulk motion. We suggest that such accretion is likely to occur in a wide variety of black hole environments, where the strong gravitational field is expected to dominate the pressure forces, and that this likely to lead to a characteristic high-ener...

The combination of the first-year Wilkinson Microwave Anisotropy Probe (WMAP) data with other finer scale cosmic microwave background (CMB) experiments (CBI and ACBAR) and two structure formation measurements (2dFGRS and Lyman α forest) suggest a ΛCDM cosmological model with a running spectral power index of primordial density fluctuations. Motivated by this new result on the index of primordia...

We consider arbitrary-angle interactions between spatial solitons and the planar boundary between two optical materials with a single power-law nonlinear refractive index. Extensive analysis has uncovered a wide range of new qualitative phenomena in non-Kerr regimes. A universal Helmholtz-Snell law describing soliton refraction is derived using exact solutions to the governing equation as a non...

DHT systems are structured overlay networks capable of using P2P resources as a scalable storage platform for very large data applications. However, their efficiency expects a level of uniformity in the association of data to index keys that is often not present in inverted indexes. Index data tends to follow non-uniform distributions, often power law distributions, creating intense local stora...