Neutral Bremsstrahlung radiation of Ne,Ar and O

The neutral Bremsstrahlung cross-sections of Ne, Ar and atomic oxygen around the 3 and 10μ wavelength regions were measured in a high temperature plasma generated in a shock tube. The results were generally a factor of three higher than the theoretical values calculated by Geltman. Agreement with the experimental results of Taylor and Caledonia around 3μ was good except for the case of Ne. The cross-sections around 10μ are the first measurements in this wavelength region. Enhanced radiation due to atomic line emission on top of the Bremsstrahlung continuum, as predicted by Hyman was observed around 7.44μ.     

Derivation modules of orthogonal duals of hyperplane arrangements

Let A be an n × d matrix having full rank n. An orthogonal dual A^⊥ of A is a (d-n) × d matrix of rank (d−n) such that every row of A^⊥ is orthogonal (under the usual dot product) to every row of A. We define the orthogonal dual for arrangements by identifying an essential (central) arrangement of d hyperplanes in n-dimensional space with the n × d matrix of coefficients of the homogeneous linear forms for which the hyperplanes are kernels. When n ≥ 5, we show that if the matroid (or the lattice of intersection) of an n-dimensional essential arrangement contains a modular copoint whose complement spans, then the derivation module of the orthogonally dual arrangement ^⊥ has projective dimension at least ⌈ n(n+2)/4 ⌉ - 3.Hal Schenck partially supported by NSF DMS 03-11142, NSA MDA 904-03-1-0006, and ATP 010366-0103.     

Non-catalytic and template-free growth of aligned CdS nanowires exhibiting high field emission current densities

Various CdS nanostructures, including nanoparticle film, bundles of quasi-aligned and well-aligned nanowires, were fabricated with a non-catalytic and template-free MOCVD process. The well-aligned CdS nanowires exhibit unusually high field emission current densities of 225 mA cm(-2) at the applied electric field of 20 V microm(-1).     

White-light generation through Ce3+/Mn2+-codoped and Eu2+-doped Ba1.2Ca0.8SiO4 T-phase phosphors

Hexagonal Ba_1.20Ca_0.8?2x?ySiO₄:xCe³⁺,xLi⁺,yMn²⁺ phosphors exhibit two emission bands peaking near 400 and 600 nm from the allowed f–d transition of Ce³⁺ ions and the forbidden ⁴T₁–⁶A₁ transition of Mn²⁺ ions, respectively. The strong interaction between Ce³⁺/Mn²⁺ ions is investigated in terms of energy transfer, crystal field effect, and microstructure by varying their concentrations. They show a higher quenching temperature of 250 °C than that of a commercially used (Ba,Sr)₂SiO₄:Eu²⁺ phosphor (150 °C). Finally, mixtures of these phosphors with green-emissive Ba_1.20Ca_0.70SiO₄:0.10Eu²⁺ are tested and yielded correlated color temperatures from 3500 to 7000 K, and color rendering indices up to 95%.     

Coalition formation with local public goods and group-size effect

Many public goods that are provided by coalitions have a group-size effect. Namely, people prefer to consume a public good in a larger coalition. This paper studies local public goods games with anonymous and separable group-size effect. The core is nonempty when coalition feasible sets are monotonic and players’ preferences over public goods satisfy a condition called cardinal connectedness. Moreover, a core allocation consists of connected coalitions.     

Development and Infrared Applications of Chalcogenide Glass Optical Fibers

Chalcogenide glass fibers based on sulphide, selenide, telluride, and their rare earth doped compositions are being actively pursued both at the Naval Research Laboratory in Washington, D.C. (NRL) and worldwide. Great strides have been made in reducing optical losses using improved chem ical purification techniques, but further improvements are needed in both purification and fiberization technology to attain the theoretical optical losses. Despite this, current singlemode and multimode chalcogenide glass fibers are enabling numerous applications. Some of these applications include laser power delivery, chemical sensing, imaging, scanning near field microscopy spectroscopy, fiber infrared (IR) sources lasers, amplifiers, and optical switches. The authors assert that the research and development of chalcogenide glasses will grow in the foreseeable future, especially with respect to improvements the optical quality of the fibers and the performance of the fibers in existing future applications.     

Analytic solutions of a two-dimensional rectangular heat equation with a heat source

The method of separation of variables is applied in order to investigate the analytical solutions of a certain two-dimensional rectangular heat equation. In the analysis presented here, the partial differential equation is directly transformed into ordinary differential equations. The closed-form transient temperature distributions and heat transfer rates are generalized for a linear combination of the products of Fourier-Bessel series of the exponential type. Relevant connections with some other closely-related recent works are also indicated.     

Preface: Old and New Perspectives on the Tutte Polynomial

This paper introduces a special issue on the Tutte polynomial derived from the Second Workshop on Tutte Polynomials and Applications, 2005, held at the Centre de Recerca Matemàtica, Bellaterra, Catalonia. We discuss the prehistory of Tutte polynomials and two current areas of research, to what extent a graph is determined by its chromatic or Tutte polynomial and generic versions of Tutte polynomials. Received February 28, 2007     

Simultaneous adiabatic spin-locking cross polarization in solid-state NMR of paramagnetic complexes

Continuous-wave irradiations cross polarization and its variations had not been a popular choice for sensitivity enhancement in paramagnetic solids due to the large spectral broadening and the effect of fast relaxation on both the source and target spins. Furthermore, with the application of very-fast sample spinning, which is the prerequisite for high-resolution purposes, polarization transfer over a large bandwidth is further degraded. In this work, we report a wideband sensitivity enhancement in paramagnetic solid with our recently developed technique, simultaneous adiabatic spin-locking cross polarization, SADIS CP. Experiments were demonstrated with Cu(II)(d,l-alanine)₂ · H₂O under high-static field of 14.1 T and very-fast sample spinning of 31 kHz.