Extinction and Persistence of Species in Discrete Competitive Systems with a Safe Refuge

AbstractWe analyze a two species discrete competition model in which one species diffuses between two patches, A and B. In this model, two species, species 1 and 2, compete in patch A with species 1 being the sedentary species. Thus, patch B is a safe refuge for species 2. We obtain sufficient conditions for the extinction of species 1. Species 2 is the superior competitor whenever a linear combination of its growth rates always exceeds the growth rate of the sedentary species 1. By using a specific example, we demonstrate that providing a safe refuge does not always make a species a superior competitor. In fact, without diffusion, species 2 drives species 1 to extinction. However, with the addition of diffusion, there is stable coexistence of the two species. If the safe refuge is not suitable for its growth and reproduction, species 2 may go extinct. We obtain sufficient conditions for the extinction of species 2. We also show that a species persists whenever all of its carrying capacities are sufficiently large. This result rules out the possibility of a population becoming arbitrarily close to zero and therefore risking extinction

Multiple Jet Blowing around the Blunt Trailing Edge of a Circulation Controlled Airfoil

A circulation controlled airfoil has a body structure with leading and trailing ends and upper and lower surfaces extending therebetween, and a cylindrical member disposed along the trailing end of the body structure between the upper and lower surfaces thereof so as to form a rounded, blunt trailing edge surface on the airfoil. A first blowing jet slot is defined between the outer surface of the cylindrical member and the trailing end of the body structure adjacent its upper surface. A second blowing jet slot is defined in a tubular wall of the cylindrical member. The latter member can be rotated to vary the distance of the second jet slot from the first jet slot and thereby adjust the point of separation of air flow along the airfoil from the outer surface of the blunt trailing edge surface formed by the cylindrical member. In such manner the lift generated by the airfoil can be optimized by providing blowing that is specifically tailored to given flight conditions. Also, the separate plenums are provided for supplying air flow to the respective jet slots

\u3ci\u3eIn situ\u3c/i\u3e ellipsometry growth characterization of dual ion beam deposited boron nitride thin films

Pure hexagonal h, as well as mixed-phase cubic/hexagonal c/h boron nitride (BN) thin films were deposited onto [001] silicon substrates using the dual ion beam deposition technique. The BN thin films were grown under UHV conditions at different substrate temperatures and ion beam bombarding parameters. Thin-film growth was monitored using in situ spectroscopic ellipsometry at 44 wavelengths between 420 and 761 nm. The in situ ellipsometric Ψ and Δ data were compared with two-layer growth model calculations for the mixed-phase c/h BN, and with one-layer growth model calculations for pure h-BN growth. In situ data provide information on the optical properties of deposited h-BN and c/h-BN material, film thickness, and BN growth rates. A virtual interface approach is employed for the optical properties of the silicon substrate. The growth and nucleation of c-BN observed here confirms the cylindrical thermal spike model. The results for composition and thickness of the BN films were compared to those obtained from ex situ infrared transmission measurements and high-resolution transmission electron microscopy investigations

Frictional quantum decoherence

The dynamics associated with a measurement-based master equation for quantum Brownian motion are investigated. A scheme for obtaining time evolution from general initial conditions is derived. This is applied to analyze dissipation and decoherence in the evolution of both a Gaussian and a Schr\"{o}dinger cat initial state. Dependence on the diffusive terms present in the master equation is discussed with reference to both the coordinate and momentum representations.Comment: 18 pages, 7 figure

Various Correspondence Relating to Archeological Artifacts Found in Great Sand Dunes National Monument

Various correspondence spanning from 1935 to 1952 relating to the discovery and handling of archeological artifacts found at Great Sand Dunes National Monument. Includes mention of Folsom projectile points and arrowheads

Bimetallic MOFs (H3O)x[Cu(MF6)(pyrazine)2]·(4 − x)H2O (M = V4+, x = 0; M = Ga3+, x = 1): co-existence of ordered and disordered quantum spins in the V4+ system

The title compounds are bimetallic MOFs containing [Cu(pyz)2]2+ square lattices linked by MF6n− octahedra. In each, only the Cu2+ spins exhibit long-range magnetic order below 3.5 K (M = V4+) and 2.6 K (M = Ga3+). The V4+ spins remain disordered down to 0.5 K

Difficult Scenarios for NMSSM Higgs Discovery at the LHC

We identify scenarios not ruled out by LEP data in which NMSSM Higgs detection at the LHC will be particularly challenging. We first review the `no-lose' theorem for Higgs discovery at the LHC that applies if Higgs bosons do not decay to other Higgs bosons - namely, with L=300 fb^-1, there is always one or more `standard' Higgs detection channel with at least a 5 sigma signal. However, we provide examples of no-Higgs-to-Higgs cases for which all the standard signals are no larger than 7 sigma implying that if the available L is smaller or the simulations performed by ATLAS and CMS turn out to be overly optimistic, all standard Higgs signals could fall below 5 sigma even in the no-Higgs-to-Higgs part of NMSSM parameter space. In the vast bulk of NMSSM parameter space, there will be Higgs-to-Higgs decays. We show that when such decays are present it is possible for all the standard detection channels to have very small significance. In most such cases, the only strongly produced Higgs boson is one with fairly SM-like couplings that decays to two lighter Higgs bosons (either a pair of the lightest CP-even Higgs bosons, or, in the largest part of parameter space, a pair of the lightest CP-odd Higgs bosons). A number of representative bench-mark scenarios of this type are delineated in detail and implications for Higgs discovery at various colliders are discussed.Comment: 31 pages, 5 figure