Physics

A comparison between magnetic and reflection loss characteristics of substituted strontium ferrite and nanocomposites of ferrite/carbon nanotubes J. Appl. Phys. 111, 07B543 Experimental study and theoretical prediction of dielectric permittivity in BaTiO3/polyimide nanocomposite films Appl. Phys. Lett. 100, 092903 High temperature x ray diffraction determination of the body-centered-cubic-face-centered-cubic transformation temperature in (Fe70Ni30)88Zr7B4Cu1 nanocomposites

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The Interactions and magnetization reversal of Ni nanowire arrays and synthetic anit-ferromagnetic coupled thin film trilayers have been investigated through first order reversal curve (FORC) method. By using a quantitative analysis of the local interaction field profile distributions obtained from FORC, it has proven to be a powerful characterization tool that can reveal subtle features of magnetic interactions.

Interactions and magnetization reversal of Ni nanowires arrays have been investigated by the first order reversal curve (FORC) method. Several series of samples with controlled spatial distribution were considered including simple wires of different lengths and diameters (70 nm and 110 nm) and complex wires with single modulated diameter along their length. Subtle features of magnetic interactions are revealed through a quantitative analysis of the local interaction field profile distributions obtained from FORC. In addition the FORC analysis indicates that the nanowire systems with a mean diameter of 70 nm appear to be organized in symmetric clusters indicative of a reversal-field memory effect.

This* study* evaluated* the* interrelationship* of* capitalisation,* market* power* and* profitability* in* Food* and* Beverages* Firms* in* Nigeria.* Specifically,* the* relationship* between* capitalisation* and* market* power,* profitability* and* market* power,* also* capitalisation*and*profitability*were*assessed.* Six* companies* were* purposively* selected* from* Food* and* Beverages* Firms,* three* from* the* Food* firms* and* three* from* the* Beverages* firms* to* meet* the* needs* of* this* panel* study.* Data* for* the* study* were* collected* using* secondary* sources* within* the* period* of* ten* years* (2001T2010).* The* interrelationships* between* capitalisation,* market* power* and*profitability*were*analysed*using*Pearson*Product*Moment*Correlation*Coefficient* (PPMCC)*and*Panel*Data*Analysis*(PDA).** Findings* indicated* that* there* is* a* positive* significant* impact* of* capitalisation* on* profitability*in*food*firms*(r*=*0.561,*p*=*0.015).*Capitalisation*has*a*positive*significant* effect* on* market* power* with* (r* =* 0.678,* p* =* 0.001)* for* food* firms,* and* (r* =* 0.932,* p* =* 0.001)* for* beverages* firms* respectively.* In* addition,* a* positive* relationship* was* also* found*to*exist*between*capitalisation*size*and*corporate*profitability*as*(r*=*0.885,*p*=* 0.000)*for*food*firms,*and*(r*=*0.643,*p*=*0.000)*for*beverages*firms.* Based*on*these*findings,*the*study*concluded*that*there*exists*a*positive*and*significant* interrelationship* between* capitalisation,* market* power* and* profitability* of* the* sampled* firms.* The* study* therefore* recommended* that* management* must* see* to* an* increase*in*total*asset*and*total*equity*that*will*lead*to*an*increase*in*market*share*and* providing*positive*return*on*equity*for*their*firms.

In this work we study vertical, acoustic propagation in a non-homogeneous media for a spatially-compact, time-harmonic source. An analytical, 2-layer model is developed representing the acoustic pressure disturbance propagating in the atmosphere. The validity of the model spans the distance from the Earth's surface to 30,000 meters. This includes the troposphere (adiabatic), ozone layer (isothermal), and part of the stratosphere (isothermal). The results of the model derivation in the adiabatic region yield pressure solutions as Bessel functions of the First (J) and Second (Y) Kind of order − 7 with an argument of 2Ωτ (where Ω represents a dimensionless frequency and τ is a dimensionless vertical height in z (vertical coordinate)). For an added second layer (isothermal region), the pressure solution is a decaying sinusoidal, exponential function above the first layer. In particular, the vertical, acoustic propagation is examined for various configurations. , where A and B are constants determined by the boundary conditions. For the 2nd class, we examine the application to a time-harmonic, compact source placed arbitrarily within the 1st layer. The method of Green's functions is used to obtain a particular solution for the model equations. This result is compared with a Fast Field Program (FFP) which was developed to test these solutions. The results show that the response given by the Green's function compares favorably with that of the FFP.

The Acoustic Reverberation Special Research Program ͑ARSRP͒ of the Office of Naval Research conducted low-frequency acoustic reverberation experiments just west of the Mid-Atlantic Ridge in 1993. Analyses of these data are supported by a bathymetric survey that produced nearly full-coverage bathymetry gridded to a resolution of 200ϫ200 m. At this scale direct-path reverberation data has been successfully modeled using Lambert's law applied to the local grazing angle determined from the high-resolution bathymetry. The analysis suggests that there could be a slightly weaker dependence on grazing angle than sine squared. The good agreement of this simple model with data shows that, for this region, two-dimensional seafloor morphology at the proper scale determines the ability to predict reverberation. For a model, such as Lambert's law, that glosses over the details of seafloor microroughness or texture at the scale the acoustic wavelength (ϭ6 m͒, the seafloor morphology scale that is critical is shown to be an order of magnitude or two greater than an acoustic wavelength. An average Lambert coefficient for the region is between Ϫ14 and Ϫ17 dB, but it is less than Ϫ20 dB for deeply sedimented areas and around Ϫ12 dB for rugged exposed rock areas. ͓S0001-4966͑97͒06605-8͔

In this work, we design a linear, two step implicit finite difference method to approximate the solutions of a biological system that describes the interaction between a microbial colony and a surrounding substrate. Three separate models are analyzed, all of which can be described as systems of partial differential equations (PDE)s with nonlinear diffusion and reaction, where the biological colony grows and decays based on the substrate bioavailability. The systems under investigation are all complex models describing the dynamics of biological films. In view of the difficulties to calculate analytical solutions of the models, we design here a numerical technique to consistently approximate the system evolution dynamics, guaranteeing that nonnegative initial conditions will evolve uniquely into new, nonnegative approximations. This property of our technique is established using the theory of M-matrices, which are nonsingular matrices where all the entries of their inverses are posit...