Using a laser aureole to invert lidar return

An aureole generated by a laser beam was studied. The strength of the signal redirected towards a sensor high above the surface by a combination of one scattering event in the marine boundary layer (mbl) and one single reflection event from the ocean surface was estimated. A model of mbl aerosol size distributions was used to estimate Mie scattering for a wide range of meteorolocial conditions. The sea surface reflection was determined from a Gaussian model of the wave slopes. These laser aureoles which were estimated over the wide range of conditions and were normalized by the reflected laser light were found to be highly correlated with the optical depth of the boundary layer. By estimating optical depth from the aureole, the Bernoulli-Riccati inversion of lidar return could be constrained and the inversion accuracy improved. A Monte Carlo program was developed to study the laser aureole generated by up to 8 orders of reflection and scattering. The aureole was generated by a narrow, 10 nsec laser pulse at 1.06 microns and measured by a receiver 10 km above the ocean surface. The original theoretical computation compared well with the Monte Carlo method. When multiple scattereffects were included, the normalized aureole was still highly correlated with the mbl optical depth over the range of conditions

The Weyl-Lanczos Equations and the Lanczos Wave Equation in 4 Dimensions as Systems in Involution

Using the work by Bampi and Caviglia, we write the Weyl-Lanczos equations as an exterior differential system. Using Janet-Riquier theory, we compute the Cartan characters for all spacetimes with a diagonal metric and for the plane wave spacetime since all spacetimes have a plane wave limit. We write the Lanczos wave equation as an exterior differential system and, with assistance from Janet-Riquier theory, we find that it forms a system in involution. This result can be derived from the scalar wave equation itself. We compute its Cartan characters and compare them with those of the Weyl-Lanczos equations.Comment: 18 pages, latex, no figures, references correcte

Antiferromagnetic order in CeCoIn5 oriented by spin-orbital coupling

An incommensurate spin density wave ($Q$ phase) confined inside the superconducting state at high basal plane magnetic field is an unique property of the heavy fermion metal CeCoIn$_5$. The neutron scattering experiments and the theoretical studies point out that this state come out from the soft mode condensation of magnetic resonance excitations. We show that the fixation of direction of antiferromagnetic modulations by a magnetic field reported by Gerber et al., Nat. Phys. {\bf 10}, 126 (2014) is explained by spin-orbit coupling. This result, obtained on the basis of quite general phenomenological arguments, is supported by the microscopic derivation of the $\chi_{zz}$ susceptibility dependence on the mutual orientation of the basal plane magnetic field and the direction of modulation of spin polarization in a multi-band metal.Comment: 7 pages plus 2 pages with 2 figure

He Scattering from Random Adsorbates, Disordered Compact Islands and Fractal Submonolayers: Intensity Manifestations of Surface Disorder

A theoretical study is made on He scattering from three fundamental classes of disordered ad-layers: (a) Translationally random adsorbates, (b) disordered compact islands and (c) fractal submonolayers. The implications of the results to experimental studies of He scattering from disordered surfaces are discussed, and a combined experimental-theoretical study is made for Ag submonolayers on Pt(111). Some of the main theoretical findings are: (1) Structural aspects of the calculated intensities from translationally random clusters were found to be strongly correlated with those of individual clusters. (2) Low intensity Bragg interference peaks appear even for scattering from very small ad-islands, and contain information on the ad-island local electron structure. (3) For fractal islands, just as for islands with a different structure, the off-specular intensity depends on the parameters of the He/Ag interaction, and does not follow a universal power law as previously proposed in the literature. In the experimental-theoretical study of Ag on Pt(111), we use first experimental He scattering data from low-coverage (single adsorbate) systems to determine an empirical He/Ag-Pt potential of good quality. Then, we carry out He scattering calculations for high coverage and compare with experiments. The conclusions are that the actual experimental phase corresponds to small compact Ag clusters of narrow size distribution, translationally disordered on the surface.Comment: 36 double-spaced pages, 10 figures; accepted by J. Chem. Phys., scheduled to appear March 8. More info available at http://www.fh.huji.ac.il/~dani

Interactions between introduced and native Anolis lizards in Florida and Grand Cayman Island

I investigated interactions between an invading species of lizard, Anolis sagrei, and native A. carolinensis in Florida and native A. conspersus in Grand Cayman. Anolis sagrei outnumbers both native species in some areas, particularly disturbed habitats, and is suspected of displacing them. Anolis carolinensis and A. conspersus are ecological analogs, and were the only anoles in Florida and Grand Cayman, respectively, until the introduction of A. sagrei. Because anoles are active, aggressive, territorial predators with size-structured populations and generalized feeding habits, I hypothesized that aggressive interference among adults and predation of juveniles by adults were important interspecific interactions. To investigate the importance of these mechanisms, I conducted behavioral experiments in both locations to determine the strength and symmetry of interspecific predation and aggressive interference. Based on the results of the behavioral experiments, I subsequently conducted experiments in the field and in enclosures to test hypotheses of interspecific interaction in relation to habitat structure and disturbance. Behavioral experiments demonstrated that (1) intraguild predation was asymmetrical in favor of A. sagrei in Florida and Grand Cayman, whereas (2) aggressive interference was minimal in Florida, but highly asymmetrical in Grand Cayman in favor of A. conspersus. A field experiment in Grand Cayman demonstrated that A. sagrei is restricted to open, disturbed habitats due to intense interspecific aggression and thus appears to have minimal impact on A. conspersus, despite its demonstrated potential to be an important intraguild predatorIn contrast, enclosure experiments in Florida demonstrated that the survival of A. carolinensis juveniles is significantly reduced in habitats of low structural complexity due to intraguild predation from adult A. sagrei and competition from juvenile A. sagrei. My studies demonstrate that (1) both intraguild predation and interspecific aggression have important influences on anole community structure, (2) the effects of an introduced species on native congeners in one community cannot necessarily be predicted by knowing the effects of that same introduced species on native congeners in a different community, and (3) predicting the effects of one species on another, regardless of taxa, will be enhanced by understanding the nature, strength and symmetry of the mechanisms of interaction