Development of Empirical Models to Rate Spruce-Fir Stands in Michigan\u27s Upper Peninsula for Hazard From the Spruce Budworm (Lepidoptera: Tortricidae): A Case History

The procedure used to develop empirical models which estimate potential spruce budworm impact to spruce-fir stands in Michigan\u27s Upper Peninsula is reviewed. Criteria used to select independent variables, to select the best of alternative multiple linear regression models. and to validate final models are discussed. Preliminary, intermediate, and final results demonstrate a cyclic pattern to the development procedure. Validation is emphasized as an important step in the procedure. Implications of using the hazard-rating system as a pest management tool in the stand management process are discussed

Self-pulsation dynamics in narrow stripe semiconductor lasers

In this paper, we address the physical origin of self-pulsation in narrow stripe edge emitting semiconductor lasers. We present both experimental time-averaged polarization-resolved near-field measurements performed with a charged-coupled device camera and picosecond time resolved near-field measurements performed with a streak camera. These results demonstrate dynamic spatial-hole burning during pulse formation and evolution. We conclude from these experimental results that the dominant process which drives the self-pulsation in this type of laser diode is carrier induced effective refractive index change induced by the spatial-hole burning

Constraints on the density dependence of the symmetry energy

Collisions involving 112Sn and 124Sn nuclei have been simulated with the improved Quantum Molecular Dynamics transport model. The results of the calculations reproduce isospin diffusion data from two different observables and the ratios of neutron and proton spectra. By comparing these data to calculations performed over a range of symmetry energies at saturation density and different representations of the density dependence of the symmetry energy, constraints on the density dependence of the symmetry energy at sub-normal density are obtained. Results from present work are compared to constraints put forward in other recent analysis.Comment: 8 pages, 4 figures,accepted for publication in Phy. Rev. Let

Root anatomical traits contribute to deeper rooting of maize under compacted field conditions

© The Author(s) 2020. To better understand the role of root anatomy in regulating plant adaptation to soil mechanical impedance, 12 maize lines were evaluated in two soils with and without compaction treatments under field conditions. Penetrometer resistance was 1–2 MPa greater in the surface 30 cm of the compacted plots at a water content of 17–20% (v/v). Root thickening in response to compaction varied among genotypes and was negatively associated with rooting depth at one field site under non-compacted plots. Thickening was not associated with rooting depth on compacted plots. Genotypic variation in root anatomy was related to rooting depth. Deeper-rooting plants were associated with reduced cortical cell file number in combination with greater mid cortical cell area for node 3 roots. For node 4, roots with increased aerenchyma were deeper roots. A greater influence of anatomy on rooting depth was observed for the thinner root classes. We found no evidence that root thickening is related to deeper rooting in compacted soil; however, anatomical traits are important, especially for thinner root classes

Using Samples of Unequal Length in Generalized Method of Moments Estimation

Many applications in financial economics use data series with different starting or ending dates. This paper describes an estimation method, based on the generalized method of moments (GMM), which makes use of all available data for each moment condition. We introduce two asymptotically equivalent estimators that are consistent, symptotically normal, and more efficient asymptotically than standard GMM. We illustrate these estimators in an application to mutual fund performance evaluation. Both estimators are extended to general patterns of missing data, and shown to be more efficient than estimators that ignore intervals of the data, and thus more efficient than standard GMM

Bulk photonic metamaterial with hyperbolic dispersion

In this work, we demonstrate a self-standing bulk three-dimensional metamaterial based on the network of silver nanowires in an alumina membrane. This constitutes an anisotropic effective medium with hyperbolic dispersion, which can be used in sub-diffraction imaging or optical cloaks. Highly anisotropic dielectric constants of the material range from positive to negative, and the transmitted laser beam shifts both toward the normal to the surface, as in regular dielectrics, and off the normal, as in anisotropic dielectrics with the refraction index smaller than one. The designed photonic metamaterial is the thickest reported in the literature, both in terms of its physical size 1cm x 1cm x 51 mm, and the number of vacuum wavelengths, N=61 at l=0.84 mm.Comment: 6 pages, 4 figur

Gas Sorption and Luminescence Properties of a Terbium(III)-Phosphine Oxide Coordination Material with Two-Dimensional Pore Topology

The structure, stability, gas sorption properties and luminescence behaviour of a new lanthanide-phosphine oxide coordination material are reported. The polymer PCM-15 is based on Tb(III) and tris(p-carboxylated) triphenylphosphine oxide and has a 5,5-connected net topology. It exhibits an infinite three-dimensional structure that incorporates an open, two-dimensional pore structure. The material is thermally robust and remains crystalline under high vacuum at 150 degrees C. When desolvated, the solid has a CO2 BET surface area of 1187 m(2) g(-1) and shows the highest reported uptake of both O-2 and H-2 at 77 K and 1 bar for a lanthanide-based coordination polymer. Isolated Tb(III) centres in the as-synthesized polymer exhibit moderate photoluminescence. However, upon removal of coordinated OH2 ligands, the luminescence intensity was found to approximately double; this process was reversible. Thus, the Tb(III) centre was used as a probe to detect directly the desolvation and resolvation of the polymer.Welch Foundation F-1738, F-1631National Science Foundation 0741973, CHE-0847763Chemistr