Dynamic Voxel Based Terrain Generation

This project is an implementation of an editable terrain system. By maintaining an octree of volumetric data and performing the mesh creation on the GPU, the program can allow for free editing of the surroundings which is then reflected in real time. This allows for real time applications to have terrain that can change depending on how the user interacts with it

RNA polymerase II from mutant and wild type strains of Caenorhabditis elegans

Includes vita.Studies of transcription in Caenorhabditis elegans, a model organism for the study of developmental genetics, should contribute to an understanding of the developmental process in metazoans. This research describes preliminary characterization of RNA polymerase II, the enzyme that transcribes messenger RNA. RNA polymerase I, II, and III from C. elegans were isolated, and their sensitivities to the fungal toxin O-amanitin measured. Sensitivities of these enzymes to amanitin were similar to those of the coresponding RNA polymerases from vertebrates. RNA polymerase II from the nematode was 50% inhibited by 7 [mu]g/ml of the amatoxin and RNA polymerase III by 80 [mu]g/ml, whereas RNA polymerase I was insensitive to 500 [mu]g/ml of the toxin. Mutants of C. elegans were isolated which can grow and reproduce in concentrations of amanitin which arrest development of wild type worms. One of these mutant strains (DR432) was shown to contain an altered RNA polymerase II which when purified was 150 times less sensitive to the amatoxin than wild type enzyme. The mutation in DR432, ama-l(ml30), is dominant and located on linkage group IV. RNA polymerase II isolated from ama-l/+ heterozygotes contains equal proportions of two components, corresponding in amanitin sensitivity to the enzymes from DR432 and wild type. Thus, ama-1 appears to affect a subunit of RNA polymerase II. A procedure was desinged for obtaining highly purified RNA polymerase II from C. elegans. The structure of the enzyme was examined by denaturing gel electrophoresis and found to consist of two large subunits ([greater than] 100 kd), and eight smaller subunits ([less than] 50 kd). The structure of the nematode RNA polymerase II closely resembles that of the corresponding enzyme from other animals. Polyclonal antibodies against C, elegans and Drosophila RNA polymerase II were shown to bind to several subunits of the C. elegans RNA polymerase II in protein blots.Includes bibliographical references

The Water Table and Soil Moisture Response Following the Removal of Conifers from an Encroached Meadow

Montane meadows play a key role in the physical and biologic processes of coniferous forests in the western United States. However, due to climate change, over grazing, and fire suppression, conifer encroachment into meadows has accelerated. In some western regions, nearly half of all meadow habitat has been loss due to conifer encroachment. To combat this issue, encroaching conifers can be removed in an attempt to increase meadow habitat and function. While multiple studies have assessed changes in soil structure and vegetation composition, few studies directly investigate changes in hydrology following meadow conifer removal projects. The goal of this study is to determine if the removal of conifers from an encroached meadow (Marian Meadow) has an effect on soil moisture and groundwater depth such that meadow hydrologic conditions are promoted. This goal will be accomplished by the following objectives: 1) develop a water budget incorporating groundwater depth, soil moisture, and climate measurements to quantify the hydrologic processes prior to and after conifer removal, 2) conduct a statistical analysis of the project meadow’s wet season water table depth prior to and after conifer removal, 3) conduct a statistical analysis of the meadow’s soil moisture prior to and after conifer removal. Marian Meadow is located in Plumas County, CA at an elevation of 4,900 feet. This 45-acre meadow enhancement project is part of a 2,046-acre timber harvest plan implemented by the Collins Pine Company. Soil moisture and water table depth sensors were installed in Marian Meadow and a control meadow in September 2013. The soil moisture sensors were installed at one and three foot depths. Soil moisture and water table depth measurements used in this study span from September 2013 through June 2016. The removal of encroaching conifers from Marian Meadow occurred in July 2015. Evapotranspiration was estimated using the Priestly Taylor equation. Electrical Resistivity Tomography (ERT) was used to determine maximum water table depths. A groundwater recession curve equation was used to model water table depths between water table depth sensor measurements and ERT measurements. Standard least squared linear regression and ANCOVA was used to determine any statistical significant difference in soil moisture and water table depths prior to and after conifer removal. The water balance indicated that the majority of Marian Meadow and the control meadow’s water storage can be attributed to precipitation and not upland sources. This hydrologic characteristic is common in dry meadows. The statistical analysis indicated that measured water table depths increased on average by 0.58 feet following conifer removal. Relative to the control meadow, soil moisture in Marian Meadow initially decreased following conifer removal. However, from November 2015 through June 2016 soil moisture increased. On average soil moisture increased by 4% following conifer removal. Also, growing season (April through September) water table depths indicated that meadow vegetation communities could be supported in Marian Meadow following conifer removal. The removal of conifers from an encroached meadow appears to promote soil moisture and water table depth conditions indicative of a meadow and meadow plant community types

Temperature transport and motional induction in the Florida Current

Differences of electrical potential across the Florida Current between Jupiter, Florida, and Settlement Point, GBI, are interpreted in terms of mean and seasonal temperature transports. The potential differences arise from the lateral transport of electrical conductivity through the vertical component of the earth\u27s magnetic field. Using the temperature and conductivity relation in the Current, the conductivity transport can be converted to temperature transport...

Accurately monitoring the Florida Current with motionally induced voltages

A new experimental technique for appraising how accurately submarine-cable (subcable) voltages monitor oceanic volume transport is presented and then used to study voltages induced by the northern Florida Current. Until recently, subcable voltages have been largely dismissed as an oceanographic tool because their interpretation can be ambiguous. They depend upon the transport field, the electrical conductance of the environment, and the mutual spatial distribution of these two quantities. To examine how these three factors affect subcable voltages at a particular site, we combine data from two different velocity profilers: XCP and PEGASUS. These instruments provide vertical profiles of velocity, temperature, and motion ally induced voltage at several sites across a transect. From this information, we determine if and why subcable voltages track volume transport. We conclude that subcable voltages measured in the northern Florida Straits accurately monitor the Florida Current transport because they are insensitive to the spatial distribution of the flow—a result that stems from a large and rather uniform seabed conductance. Subcable voltages should be reconsidered for oceanic monitoring elsewhere because the validity of their interpretation can now be assessed

On the relationship between transport and motional electric potentials in broad, shallow currents

Knowledge of the volume transport is of great practical importance in many studies of the flow through or within shallow channels and estuaries. However, transport measurements are often difficult to obtain because of the temporal or spatial variability of the flow. The bulk motion of a stream has been inferred from measurements which integrate the electric field induced by the motion of seawater through the earth\u27s magnetic field...

Fourier-Domain Wavefield Rendering for Rapid Simulation of Synthetic Aperture Sonar Data

This paper introduces a new method for simulating synthetic aperture sonar (SAS) raw coherent echo data that is orders of magnitude faster than the commonly used point and facet diffraction models. The new approach uses Fourier wavefield generation and propagation in combination with a highly optimised optical rendering engine. It has been shown to produce a quantifiably similar quality of data and data products (i.e., images and spectra) to a point-diffraction model, capturing the important coherent wave physics (including diffraction, speckle, aspect-dependence, and layover) as well as effects of the SAS processing chain (including image focusing errors and artefacts). This new simulation capability may be an enabler for augmenting data sets with physically accurate and diverse synthetic data for robust machine learning

Occlusion Modeling for Coherent Echo Data Simulation:A Comparison Between Ray-Tracing and Convex-Hull Methods

The ability to simulate realistic coherent datasets for synthetic aperture imaging systems is crucial for the design, development and evaluation of the sensors and their signal processing pipelines, machine learning algorithms and autonomy systems. In the case of synthetic aperture sonar (SAS), collecting experimental data is expensive and it is rarely possible to obtain ground truth of the sensor’s path, the speed of sound in the medium, and the geometry of the imaged scene. Simulating sonar echo data allows signal processing algorithms to be tested with known ground truth, enabling rapid and inexpensive development and evaluation of signal processing algorithms. The de-facto standard for simulating conventional high-frequency (i.e., > 100 kHz) SAS echo data from an arbitrary sensor, path and scene is to use a point-based or facet-based diffraction model. A crucial part of this process is acoustic occlusion modeling. This article describes a SAS simulation pipeline and compares implementations of two occlusion methods; ray-tracing, and a newer approximate method based on finding the convex hull of a transformed point cloud. The full capability of the simulation pipeline is demonstrated using an example scene based on a high-resolution 3D model of the SS Thistlegorm shipwreck which was obtained using photogrammetry. The 3D model spans a volume of 220 × 130 × 25 m and is comprised of over 30 million facets that are decomposed into a cloud of almost 1 billion points. The convex-hull occlusion model was found to result in simulated SAS imagery that is qualitatively indistinguishable from the ray-tracing approach and quantitatively very similar, demonstrating that use of this alternative method has potential to improve speed while retaining high fidelity of simulation.The convex-hull approach was found to be up to 4 times faster in a fair speed comparison with serial and parallel CPU implementations for both methods, with the largest performance increase for wide-beam systems. The fastest occlusion modeling algorithm was found to be GPU-accelerated ray-tracing over the majority of scene scales tested, which was found to be up to 2 times faster than the parallel CPU convex-hull implementation. Although GPU implementations of convex hull algorithms are not currently readily available, future development of GPU-accelerated convex-hull finding could make the new approach much more viable. However, in the meantime, ray-tracing is still preferable, since it has higher accuracy and can leverage existing implementations for high performance computing architectures for better performance

Simulations of the angular dependence of the dipole-dipole interaction among Rydberg atoms

The dipole-dipole interaction between two Rydberg atoms depends on the relative orientation of the atoms and on the change in the magnetic quantum number. We simulate the effect of this anisotropy on the energy transport in an amorphous many atom system subject to a homogeneous applied electric field. We consider two experimentally feasible geometries and find that the effects should be measurable in current generation imaging experiments. In both geometries atoms of $p$ character are localized to a small region of space which is immersed in a larger region that is filled with atoms of $s$ character. Energy transfer due to the dipole-dipole interaction can lead to a spread of $p$ character into the region initially occupied by $s$ atoms. Over long timescales the energy transport is confined to the volume near the border of the $p$ region which is suggestive of Anderson localization. We calculate a correlation length of 6.3~$\mu$m for one particular geometry.Comment: 6 pages, 5 figures, revised draf