The spectrum allocation for cognitive radio sensor networks (CRSNs) has received considerable research attention under the assumption that the spectrum environment is static. However, in practice, the spectrum environment varies over time due to primary user/secondary user (PU/SU) activity and mobility, resulting in time-varied spectrum resources. This paper studies resource allocation for chun...

Managing trade-offs through gene regulation is believed to confer resilience to a microbial community in a fluctuating resource environment. To investigate this hypothesis, we imposed a fluctuating environment that required the sulfate-reducer Desulfovibrio vulgaris to undergo repeated ecologically relevant shifts between retaining metabolic independence (active capacity for sulfate respiration...

The final state of the gravitational collapse of a marginally bound dust cloud is formulated in terms of an existence problem for the non-linear differential equation governing radial null geodesics near the singular point. Rigorous results are proved, covering the complete spectrum of the possible initial data.

The continuous spectrum and soliton solutions for the Boussinesq equation are investigated using the ∂̄-dressing method. Solitons demonstrate quite extraordinary behavior; they may decay or form a singularity in a finite time. Formation of singularity (collapse of solitons) for the Boussinesq equation was discovered several years ago. Systematic study of the solitonic sector is presented. © 2002...

This paper reviews recent work on spread spectrum network capacity. The network is shown to have a capacity that is equitably shared amongst the users via power control. This solution is much simpler than the bandwidth partitioning of the FDMA/reuse approach. The capacity gains from using spread spectrum, arising from the averaging and multiplexing, are also emphasised.

Declines in pollinator populations may harm biodiversity and agricultural productivity. Little attention has, however, been paid to the systemic response of mutualistic communities to global environmental change. Using a modelling approach and merging network theory with theory on critical transitions, we show that the scale and nature of critical transitions is likely to be influenced by the a...

We have discovered a population of extremely red galaxies at z ≃ 1.5 which have apparent stellar ages of > ∼ 3 Gyr, based on detailed spectroscopy in the rest-frame ultraviolet. In order for galaxies to have existed at the high collapse redshifts indicated by these ages, there must be a minimum level of power in the density fluctuation spectrum on galaxy scales. This paper compares the required...

In this paper we examine aspects of primordial star formation in a gravitino warm dark matter universe with a cosmological constant (ΛWDM). We compare a set of simulations using a single cosmological realization but with a wide range of warm dark matter particle masses which have not yet been conclusively ruled out by observations. The addition of a warm dark matter component to the initial pow...

I present several simple figures to illustrate cosmology and structure formation in a nutshell. Then I discuss the following argument: if we assume that ΩΛ = 0 then the CMB results favor high Ωm while the supernova results favor low Ωm. This large inconsistency is strong evidence for the incorrectness of the ΩΛ = 0 assumption. Finally I discuss recent CMB results on the slope and normalization ...

Methods to improve bearing capacity of footing resting of collapsing soil can, in fact, take two approaches, improving soil strength properties and intrusion of reinforcing sorces into soil. The footing is modeled by a square steel plate 0.1 by 0.1 m. The footing is loaded as to have a stress of 40 kPa and settlement is receded in dry and in soaking conditions. Two depths of the geo-mesh reinfo...