Defining the Relevant Forum: The United States Postal Service Constitutes a Single Forum for Communication

The United States Postal Service fulfills a vital public function by enabling people to communicate in an effective and efficient way. The United States Supreme Court has firmly established the use of the mails as a free speech right guaranteed by the First Amendment. Courts apply a three-part forum analysis when analyzing First Amendment challenges to restrictions on the use of the mail system. This analysis requires courts to define the forum to which the plaintiff seeks access, to determine if that forum is public or nonpublic, and to apply the level of scrutiny proper to the type of forum at issue. Courts have thoroughly analyzed the scope of the relevant forum in various situations where plaintiffs have sought access to government-run fora. However, the U.S. Supreme Court has not yet defined the scope of the forum when the use of the mail system is at issue, and lower courts do not agree on the proper application of the first step of forum analysis. This Comment argues that when a plaintiff seeks greater access to the mail system, courts should analogize to other situations to hold that the relevant forum is the mail system as a whole

Development of systems and techniques for landing an aircraft using onboard television

A flight program was conducted to develop a landing technique with which a pilot could consistently and safely land a remotely piloted research vehicle (RPRV) without outside visual reference except through television. Otherwise, instrumentation was standard. Such factors as the selection of video parameters, the pilot's understanding of the television presentation, the pilot's ground cockpit environment, and the operational procedures for landing were considered. About 30 landings were necessary for a pilot to become sufficiently familiar and competent with the test aircraft to make powered approaches and landings with outside visual references only through television. When steep approaches and landings were made by remote control, the pilot's workload was extremely high. The test aircraft was used as a simulator for the F-15 RPRV, and as such was considered to be essential to the success of landing the F-15 RPRV

Ab Initio Study of Hybrid b-bar-gb Mesons

Hybrid b-bar-gb molecules in which the heavy b-bar-b pair is bound together by the excited gluon field g are studied using the Born-Oppenheimer expansion and numerical simulations. The consistency of results from the two approaches reveals a simple and compelling physical picture for heavy hybrid states.Comment: 4 pages, 3 figures, uses REVTeX and epsf, final published versio

Testing contrast agents to improve micro computerized tomography (μCT) for spatial location of organic matter and biological material in soil

Soil carbon is essential for soil and ecosystem functioning. Its turnover and storage in soil are multifaceted processes that involve microbial activity in complex physical matrices. Biological litter, which include plants, animals, and microorganisms, is decomposed in soil stimulating soil biota (archaea, bacteria, fungi, protists, and animals) activity and yielding soil organic matter (SOM). Such decomposition processes are influenced by local physico-chemical characteristics including the spatial distribution of aggregates and pores. More refined analytical tools are needed to better understand these processes, especially considering the spatial 3D structure of soil matrices. Using synchrotron radiation (X-ray) micro computerized tomography (SR-μCT), we tested different contrast agents (staining methods) based on silver (Ag), eosin (Br based), and liquid and gaseous iodine (I) in order to spatially image biological material and SOM in soil samples. We also performed K-edge SR-μCT for the Ag and I2 treatments and conventional μCT for additional soil samples applying the I2 treatment. Our results indicated that I2 was the most efficient contrast method for SR-μCT imaging of soil samples. I2 qualitatively improved the images, but mainly, by using the K-edge SR-μCT, this method provided a powerful tool to determine the spatial location of SOM. We acknowledge that the use of SR-μCT is an expensive technique to study soil samples, which comes with bottlenecks in terms of access to facilities and measurement time. Nevertheless, we show that the I2 treatment improved soil images also using standard μCT. In conventional μCT the I2 treatment improved the visualization of biological material and consequently improved the qualitative analysis of fine plants roots and micro-fauna (Collembola). This improvement may have a positive implication in soil biology, by improving a non-destructive method to detect fungi (SR-μCT), soil fauna (conventional μCT) and roots in undisturbed soil samples. An unexpected finding was that the I2 treatment also stained the plastic sample containers (nylon and polyimide), indicating the potential for the I2 staining procedure to be applied for the detection of plastic pollution in soil samples

Measurement of hybrid content of heavy quarkonia using lattice NRQCD

Using lowest-order lattice NRQCD to create heavy meson propagators and applying the spin-dependent interaction, $c_B^{} \frac{-g}{2m_q}\vec\sigma\cdot\vec{B}$, at varying intermediate time slices, we compute the off-diagonal matrix element of the Hamiltonian for the quarkonium-hybrid two-state system. Thus far, we have results for one set of quenched lattices with an interpolation in quark mass to match the bottomonium spectrum. After diagonalization of the two-state Hamiltonian, we find the ground state of the $\Upsilon$ to show a $0.0035(1)c_B^2$ (with $c_B^2 \sim 1.5-3.1$) probability admixture of hybrid, $|b\bar{b}g>$.Comment: 11 pages, 4 figures, to appear in Phys Rev

Beyond the quark model of hadrons from lattice QCD

Lattice QCD can give direct information on OZI-violating contributions to mesons. Here we explore the contributions that split flavour singlet and non-singlet meson masses. I discuss in detail the spectrum and decays for scalar mesons (ie including glueball effects). I also review the status of hybrid mesons and their decays.Comment: to appear in proceedings of QNP2002, 3 pages, LATEX, 2 ps figure

Unquenched Charmonium with NRQCD - Lattice 2000

We present results from a series of NRQCD simulations of the charmonium system, both in the quenched approximation and with n_f = 2 dynamical quarks. The spectra show evidence for quenching effects of ~10% in the S- and P-hyperfine splittings. We compare this with other systematic effects. Improving the NRQCD evolution equation altered the S-hyperfine by as much as 20 MeV, and we estimate radiative corrections may be as large as 40%.Comment: Lattice 2000 (Heavy Quark Physics

Measuring the aspect ratio renormalization of anisotropic-lattice gluons

Using tadpole inproved actions we investigate the consistency between different methods of measuring the aspect ratio renormalization of anisotropic-lattice gluons for bare aspect ratios \chi_0=4,6,10 and inverse lattice spacing in the range a_s^{-1}=660-840 MeV. The tadpole corrections to the action, which are established self-consistently, are defined for two cases, mean link tadpoles in Landau gauge and gauge invariant mean plaquette tadpoles. Parameters in the latter case exhibited no dependence on the spatial lattice size, L, while in the former, parameters showed only a weak dependence on L easily extrapolated to L=\infty. The renormalized anisotropy \chi_R was measured using both the torelon dispersion relation and the sideways potential method. We found good agreement between these different approaches. Any discrepancy was at worst 3-4% which is consistent with the effect of lattice artifacts that for the torelon we estimate as O(\a_Sa_s^2/R^2) where R is the flux-tube radius. We also present some new data that suggests that rotational invariance is established more accurately for the mean-link action than the plaquette action.Comment: LaTeX 18 pages including 7 figure