Linguistics

Contains reports on two research projects.National Institute of Mental Health (Grant MH-13390-03

Computational/Experimental Aeroheating Predictions for X-33

Laminar and turbulent heating-rate calculations from an "engineering" code and laminar calculations from a "benchmark" Navier-Stokes code are compared with experimental wind-tunnel data obtained on several candidate configurations for the X-33 Phase 2 flight vehicle. The experimental data were obtained at a Mach number of 6 and a freestream Reynolds number ranging from 1 to 8 x 10(exp 6)/ft. Comparisons are presented along the windward symmetry plane and in a circumferential direction around the body at several axial stations at angles of attack from 20 to 40 deg. The experimental results include both laminar and turbulent flow. For the highest angle of attack some of the measured heating data exhibited a "non-laminar" behavior which caused the heating to increase above the laminar level long before "classical" transition to turbulent flow was observed. This trend was not observed at the lower angles of attack. When the flow was laminar, both codes predicted the heating along the windward symmetry plane reasonably well but under-predicted the heating in the chine region. When the flow was turbulent the LATCH code accurately predicted the measured heating rates. Both codes were used to calculate heating rates over the X-33 vehicle at the peak heating point on the design trajectory and they were found to be in very good agreement over most of the vehicle windward surface

Hypersonic Boundary-Layer Transition for X-33 Phase 2 Vehicle

A status review of the experimental and computational work performed to support the X-33 program in the area of hypersonic boundary-layer transition is presented. Global transition fronts are visualized using thermographic phosphor measurements. Results are used to derive transition correlations for "smooth body" and discrete roughness data and a computational tool is developed to predict transition onset for X-33 using these results. The X-33 thermal protection system appears to be conservatively designed for transition effects based on these studies. Additional study is needed to address concerns related to surface waviness. A discussion of future test plans is included

Revised Status of Rare and Endangered Unionaea (Mollusca: Margaritiferidae, Unionidae) in Arkansas

Harris and Gordon (1987) reviewed the distribution and status of 18 rare and /or endangered unionacean bivalve species (commonly referred to as clams, mussels, freshwater mussels, naiads) that occur or have occurred in Arkansas. They discussed four species that were federally listed as endangered, four species that were considered endangered or extirpated within Arkansas, four species considered threatened within Arkansas, four species of special concern within Arkansas, and two species for which the conservation status was considered uncertain due to questions regarding taxonomic validity. Numerous unionacean field surveys have been performed during 1986 1996, and a substantial database of new distributional and relative abundance information has been accumulated. Two additional unionacean species have been listed as federally endangered, one additional species has been listed as federally threatened, and one endangered species has been newly discovered within Arkansas bringing the total number of federally protected unionacean species occurring within Arkansas to eight. The conservation status of 16 additional unionacean species occurring in Arkansas is discussed also

Growth Curves of Four Species of Commercially Valuable Freshwater Mussels (Bivalva: Unionidae)

North American freshwater mussels (Bivalvia: Unionidae) have been exploited commercially for over 100 years and have been regulated using shell size limits and/or harvest seasons. Presently, freshwater mussels are considered a threatened faunal group in North America due to the large numbers of endangered, threatened or special concern species. Therefore, management of this fauna should emphasize their long-term sustainability. The objectives of this study were 1) to construct von Bertalanffy growth curves for selected commercially-most-valuable species, Fusconaia ebena, Megalonaias nervosa, Amblema plicata and Quadrula quadrula, from five rivers and two reservoirs, 2) to compare species-specific von Bertalanffy growth curves from different rivers and reservoirs, and 3) to provide information on size at onset of sexual maturity in F. ebena and A. plicata. Von Bertalanffy growth curves of four commercially valuable Ambleminae species were used in this study to compare drainage-specific growth. Growth curves for all four species investigated were significantly different between pairs of drainages. Approximate size at onset of sexual maturity was determined for Arkansas F. ebena and A. plicata. Von Bertalanffy growth curves, coupled with life history and population dynamics information, could be useful in assessing and determining national/state harvest sizes and/or drainage specific harvest sizes once annual growth line formation is confirmed

On Parking Functions and The Tower of Hanoi

The displacement of a parking function measures the total difference between where cars want to park and where they ultimately park. In this article, we prove that the set of parking functions of length $n$ with displacement one is in bijection with the set of ideal states in the famous Tower of Hanoi game with $n+1$ disks and $n+1$ pegs, both sets being enumerated by the Lah numbers.Comment: 7 pages; 4 figures (5 image files); Final version to appear in The American Mathematical Monthl

A single-photon transistor using nano-scale surface plasmons

It is well known that light quanta (photons) can interact with each other in nonlinear media, much like massive particles do, but in practice these interactions are usually very weak. Here we describe a novel approach to realize strong nonlinear interactions at the single-photon level. Our method makes use of recently demonstrated efficient coupling between individual optical emitters and tightly confined, propagating surface plasmon excitations on conducting nanowires. We show that this system can act as a nonlinear two-photon switch for incident photons propagating along the nanowire, which can be coherently controlled using quantum optical techniques. As a novel application, we discuss how the interaction can be tailored to create a single-photon transistor, where the presence or absence of a single incident photon in a ``gate'' field is sufficient to completely control the propagation of subsequent ``signal'' photons.Comment: 20 pages, 4 figure

Unionoida (Mollusca: Margaritiferidae, Unionidae) in Arkansas, Third Status Review

We analyzed stream inventories, phylogeographic studies, community and population estimates, life history and reproductive biology research, and suitable habitat investigations conducted from 1997-2008, as well as the Arkansas Natural Heritage Commission mussel database, to update the conservation status for all native freshwater unionoid bivalves thought to occur in Arkansas. Prior to this study, Harris et al. (1997) reviewed the distribution and status of 75 freshwater mussels considered native to Arkansas and ranked 22 species as endangered, threatened or special concern. We now recognize 85 mussel taxa in Arkansas; however, some of those have yet to be described or their nomenclature remains in a state of flux. The previous inclusion of Fusconaia subrotunda (I. Lea 1831) and Obovaria subrotunda (Rafinesque 1820) in the Arkansas native mussel fauna was based on misidentifications. Within the Arkansas mussel fauna, 19 species (22%) are now considered Endangered, 5 species (6%) are ranked as Threatened, 20 species (24%) are of Special Concern, and unfortunately, 1 species has probably been extirpated

Annotations for Rule-Based Models

The chapter reviews the syntax to store machine-readable annotations and describes the mapping between rule-based modelling entities (e.g., agents and rules) and these annotations. In particular, we review an annotation framework and the associated guidelines for annotating rule-based models of molecular interactions, encoded in the commonly used Kappa and BioNetGen languages, and present prototypes that can be used to extract and query the annotations. An ontology is used to annotate models and facilitate their description