Visual display and alarm system for wind tunnel static and dynamic loads

A wind tunnel balance monitor and alarm system developed at NASA Ames Research Center will produce several beneficial results. The costs of wind tunnel delays because of inadvertent balance damage and the costs of balance repair or replacement can be greatly reduced or eliminated with better real-time information on the balance static and dynamic loading. The wind tunnel itself will have enhanced utility with the elimination of overly cautious limits on test conditions. The microprocessor-based system features automatic scaling and 16 multicolored LED bargraphs to indicate both static and dynamic components of the signals from eight individual channels. Five individually programmable alarm levels are available with relay closures for internal or external visual and audible warning devices and other functions such as automatic activation of external recording devices, model positioning mechanisms, or tunnel shutdown

Reproductive Isolation and Hybridization Dynamics in Threatened Caribbean Acroporid Corals

The Caribbean corals, Acropora palmata and A. cervicornis, are abundant in fossil records but have recently undergone drastic declines primarily as a result of disease. Acropora prolifera, a hybrid of these species, has no fossil record and was previously considered rare and to occupy nonparental habitats. Now, hybrids have equivalent or greater abundance than the parental species and have expanded into the parental habitat at some sites. Previous molecular studies have demonstrated regional variability in unidirectional introgression of A. palmata genes into A. cervicornis. The goals of this dissertation are (1) to determine the strength of prezygotic mechanisms and to establish the likelihood of density dependent reproductive isolation, (2) to determine the strength of intrinsic and extrinsic postzygotic barriers, and (3) to ascertain if hybrid populations are composed of rare hybridization events that have asexually fragmented, or if colonies are genotypically distinct suggesting separate hybrid events. Overall barriers to hybridization in this genus are weak, and the efficacy of these semipermeable isolating mechanisms may depend on density. In addition, hybrids are as viable as the parental species at a variety of life history stages and are less or equally susceptible to the typical afflictions that have lead to their decline. Most hybrid populations do not seem to be composed of a single hybridization event that has asexually propagated, but rather the genotypic diversity varies across sites with up to 17 different distinct genets in one population. Taken together, it appears that hybridization in a threatened Caribbean genus is evolutionarily significant with a range of possible outcomes from the benefit of novel alleles to the swamping of A. cervicornis’ genome. These outcomes may hinge on the ability of the Caribbean acroporids to withstand the onslaught of threats that currently faces this genus (i.e. Allee Effect, disease, predation, increased sea temperature, ocean acidification, and increased disturbances)

Effects of cosmic rays on single event upsets

Assistance was provided to the Brookhaven Single Event Upset (SEU) Test Facility. Computer codes were developed for fragmentation and secondary radiation affecting Very Large Scale Integration (VLSI) in space. A computer controlled CV (HP4192) test was developed for Terman analysis. Also developed were high speed parametric tests which are independent of operator judgment and a charge pumping technique for measurement of D(sub it) (E). The X-ray secondary effects, and parametric degradation as a function of dose rate were simulated. The SPICE simulation of static RAMs with various resistor filters was tested

Reticulate Evolution and Marine Organisms: The Final Frontier?

The role that reticulate evolution (i.e., via lateral transfer, viral recombination and/or introgressive hybridization) has played in the origin and adaptation of individual taxa and even entire clades continues to be tested for all domains of life. Though falsified for some groups, the hypothesis of divergence in the face of gene flow is becoming accepted as a major facilitator of evolutionary change for many microorganisms, plants and animals. Yet, the effect of reticulate evolutionary change in certain assemblages has been doubted, either due to an actual dearth of genetic exchange among the lineages belonging to these clades or because of a lack of appropriate data to test alternative hypotheses. Marine organisms represent such an assemblage. In the past half-century, some evolutionary biologists interested in the origin and trajectory of marine organisms, particularly animals, have posited that horizontal transfer, introgression and hybrid speciation have been rare. In this review, we provide examples of such genetic exchange that have come to light largely as a result of analyses of molecular markers. Comparisons among these markers and between these loci and morphological characters have provided numerous examples of marine microorganisms, plants and animals that possess the signature of mosaic genomes

Weak Prezygotic Isolating Mechanisms in Threatened Caribbean Acropora Corals

The Caribbean corals, Acropora palmata and A. cervicornis, recently have undergone drastic declines primarily as a result of disease. Previous molecular studies have demonstrated that these species form a hybrid (A. prolifera) that varies in abundance throughout the range of the parental distribution. There is variable unidirectional introgression across loci and sites of A. palmata genes flowing into A. cervicornis. Here we examine the efficacy of prezygotic reproductive isolating mechanisms within these corals including spawning times and choice and no-choice fertilization crosses. We show that these species have subtly different mean but overlapping spawning times, suggesting that temporal isolation is likely not an effective barrier to hybridization. We found species-specific differences in gametic incompatibilities. Acropora palmata eggs were relatively resistant to hybridization, especially when conspecific sperm are available to outcompete heterospecific sperm. Acropora cervicornis eggs demonstrated no evidence for gametic incompatibility and no evidence of reduced viability after aging four hours. This asymmetry in compatibility matches previous genetic data on unidirectional introgression

Holomorphic symmetric differentials and a birational characterization of Abelian Varieties

A generically generated vector bundle on a smooth projective variety yields a rational map to a Grassmannian, called Kodaira map. We answer a previous question, raised by the asymptotic behaviour of such maps, giving rise to a birational characterization of abelian varieties. In particular we prove that, under the conjectures of the Minimal Model Program, a smooth projective variety is birational to an abelian variety if and only if it has Kodaira dimension 0 and some symmetric power of its cotangent sheaf is generically generated by its global sections.Comment: UPDATED: more details added on main proo

Using atmospheric model output to simulate the meteorological tsunami response to Tropical Storm Helene (2000)

[1] In the fall of both 1999 and 2000, unexpected “rapid tides” occurred along the coast of the Avalon Peninsula of Newfoundland. These rapid tides have been linked to the passing of Tropical Storm Jose (1999) and Tropical Storm Helene (2000) over the Grand Banks. Here we examine the dynamic ocean response to Tropical Storm Helene (2000) using a barotropic shallow water ocean model forced by atmospheric pressure and surface winds derived from a simulation of Helene using a dynamical model of the atmosphere. The ocean model is able to capture the main features of the observed response at the coast of Newfoundland as seen in the available tide gauge data. Results show that the simulated sea level response at the coast is driven by a combination of wind stress and atmospheric pressure forcing, the former generally dominating. An exception is Conception Bay, Newfoundland, where the response is captured mainly by atmospheric pressure forcing. Offshore near the edge of the Grand Banks, atmospheric pressure and wind stress forcing are equally important. The wind-forced response depends on the divergence of the surface wind stress and hence on the structure of the storm in the atmospheric model simulation. Sensitivity studies show the importance of having a small time interval (on the order of minutes) at which the atmospheric forcing is supplied to the ocean model and show the importance of the location of the storm track