A Hydrologic Model of the Provo River Basin, Utah

The purpose of this paper is to develop a general hydrologic model for use on a digital computer and prove it s validity by applying it to a management study of the Provo River Basin. Hydrologic equations have been proposed for each major hydrologic occurrence within a river basin. By linking these equations through restrictions on continuity of mass, a general hydrologic model can be obtained. Such a model becomes the basic tool for studying the management of the river basin hydrology. The paper describes the model components, parameter identification program, and the river basin management program

Development of a Water Quality Model Applicable to Great Salt Lake, Utah

The development of a model capable of predicting the long term (seasonal) distribution of water quality constituents within Great Salt Lake was undertaken as a portion of the ongoing Great Salt Lake project at Utah State University. The overall goal of the project is the development of a modeling framework to assist the relevant decision making bodies in the comprehensive management of the Great Salt Lake system. Phase I of the project provided the overall structural framework for management of the Great Salt Lake system, identified data needs, and established priorities for the development of submodels for incorporation into the overall framework. Phase II of the project involves the process of developing submodels, and Phase III will be concerned with application of the framework of models to specific management problems. This study provides, as part of the second phase of the Great Salt Lake project, a model capable of predicting the long term distribution of quality constituents within the lake. This capability is a necessary component of the modeling framework since it will allow the investigation of the effects which alternative water quality management plans will have on the distribution of water quality constituents within the lake. The water quality model of the lake is based on the application of the advection-diffusion equation to the three-dimensional transport of a quality constituent. The modeling technique is formulated by discretizing the system as a network of nodes interconnected by channels in both the horizontal and vertical directions. This representation of the system allowed the horizontal transport to be treated mathematically as one-dimensional. The resulting modeling technique is applicable to any lake, estuary, or bay in which the concentration gradients must be described in all three coordinate directions. In applying the model to Great Salt Lake a two-layered vertical network was employed due t o the physical characteristics of the system. The model was further simplified by describing vertical transport by diffusion alone. Using observed total dissolved solids concentrations, a method was developed during the study for establishing the vertical diffusion coefficient as a function of depth. A unique feature of this water quality modeling technique is that it allows the seasonal distribution of a quality constituent to be studied without the necessity of developing a hydrodynamic model of the system . The advective transport is designed to be input to the model based on observed long term circulation patterns . In the case of Great Salt Lake, circulation patterns are not yet well known. However, approximate patterns h a ,, e been established from some observations to date , and those were used to provide preliminary tests of the validity and response characteristics of the model. These tests have demonstrated that the model will be a practical and useful tool for monitoring the distribution of quality constituents within the lake

Hearing in the Juvenile Green Sea Turtle (Chelonia mydas): A Comparison of Underwater and Aerial Hearing Using Auditory Evoked Potentials

Sea turtles spend much of their life in aquatic environments, but critical portions of their life cycle, such as nesting and hatching, occur in terrestrial environments, suggesting that it may be important for them to detect sounds in both air and water. In this study we compared underwater and aerial hearing sensitivities in five juvenile green sea turtles (Chelonia mydas) by measuring auditory evoked potential responses to tone pip stimuli. Green sea turtles detected acoustic stimuli in both media, responding to underwater stimuli between 50 and 1600 Hz and aerial stimuli between 50 and 800 Hz, with maximum sensitivity between 200 and 400 Hz underwater and 300 and 400 Hz in air. When underwater and aerial hearing sensitivities were compared in terms of pressure, green sea turtle aerial sound pressure thresholds were lower than underwater thresholds, however they detected a wider range of frequencies underwater. When thresholds were compared in terms of sound intensity, green sea turtle sound intensity level thresholds were 2–39 dB lower underwater particularly at frequencies below 400 Hz. Acoustic stimuli may provide important environmental cues for sea turtles. Further research is needed to determine how sea turtles behaviorally and physiologically respond to sounds in their environment

Spin Hall Conductance of the Two Dimensional Hole Gas in a Perpendicular Magnetic Field

The charge and spin Hall conductance of the two-dimensional hole gas within the Luttinger model with and without inversion symmetry breaking terms in a perpendicular magnetic field are studied, and two key phenomena are predicted. The sign of the spin Hall conductance is modulated periodically by the external magnetic field, which means a possible application in the future. Furthermore, a resonant spin Hall conductance in the two-dimensional hole gas with a certain hole density at a typical magnetic field is indicated, which implies a likely way to firmly establish the intrinsic spin Hall effect. The charge Hall conductance is unaffected by the spin-orbit coupling.Comment: accepted for publication in Phys. Rev. B; 6 pages, 4 figure

Management of the Great Salt Lake: A Research Plan and Strategy

The primary purposes of this report are to indicate the following two research items in connection with the management of the water resource system of the Great Salt Lake:\ 1. Research needs and priorities. 2. A research coordination strategy. Research needs are identified by the report in terms of (1) various management, or use, categories (such as lake industries), and (2) the need to understand the physical characteristics of the lake system itself. The research needs are identified in each category as information (including data) or understanding gaps, in cases where there seems to be sufficient information, a research need is assumed not to exist. In the case of the Great Salt Lake system, the development of a management plan is still in the early stages, so that research needs are not prioritized in terms of a specific plan. However, the various research needs are grouped into four broad categories in terms of priority levels for pro viding planners with the needed information to proceed logically with the development of a management plan which of necessity will by dynamic in terms of changing social needs and priorities. In order for research to develop information about the lake system in accordance with management needs and priorities, a research coordination procedure is proposed. The objective of this procedure is to coordinate research between carious funding sources and research organizations and groups

The Energy Spectrum of Primary Cosmic Ray Electrons in Clusters of Galaxies and Inverse Compton Emission

Models for the evolution of the integrated energy spectrum of primary cosmic ray electrons in clusters of galaxies have been calculated, including the effects of losses due to inverse Compton (IC), synchrotron, and bremsstrahlung emission, and Coulomb losses to the intracluster medium (ICM). The combined time scale for these losses reaches a maximum of ~3e9 yr for electrons with a Lorentz factor ~300. Only clusters in which there has been a substantial injection of relativistic electrons since z <~ 1 will have any significant population of primary cosmic ray electrons at present. In typical models, there is a broad peak in the electron energy distribution extending to gamma~300, and a steep drop in the electron population beyond this. In clusters with current particle injection, there is a power-law tail of higher energy electrons with an abundance determined by the current rate of injection. A significant population of electrons with gamma~300, associated with the peak in the particle loss time, is a generic feature of the models. The IC and synchrotron emission from these models was calculated. In the models, EUV and soft X-ray emission are nearly ubiquitous. This emission is produced by electrons with gamma~300. The spectra are predicted to drop rapidly in going from the EUV to the X-ray band. The IC emission also extends down the UV, optical, and IR bands with a fairly flat spectrum. Hard X-ray (HXR) and diffuse radio emission due to high energy electrons (gamma~10e4) is present only in clusters which have current particle acceleration. Assuming that the electrons are accelerated in ICM shocks, one would only expect diffuse HXR/radio emission in clusters which are currently undergoing a large merger.Comment: Accepted for publication in the Astrophysical Journal, with minor revisons to wording for clarity and one additional reference. 19 pages with 16 embedded Postscript figures in emulateapj.sty. Abbreviated abstract belo

Hypersonic Boundary Layer Measurements with Variable Blowing Rates Using Molecular Tagging Velocimetry

Measurements of mean and instantaneous streamwise velocity profiles in a hypersonic boundary layer with variable rates of mass injection (blowing) of nitrogen dioxide (NO2) were obtained over a 10-degree half-angle wedge model. The NO2 was seeded into the flow from a slot located 29.4 mm downstream of the sharp leading edge. The top surface of the wedge was oriented at a 20 degree angle in the Mach 10 flow, yielding an edge Mach number of approximately 4.2. The streamwise velocity profiles and streamwise fluctuating velocity component profiles were obtained using a three-laser NO2->NO photolysis molecular tagging velocimetry method. Observed trends in the mean streamwise velocity profiles and profiles of the fluctuating component of streamwise velocity as functions of the blowing rate are described. An effort is made to distinguish between the effect of blowing rate and wall temperature on the measured profiles. An analysis of the mean velocity profiles for a constant blowing rate is presented to determine the uncertainty in the measurement for different probe laser delay settings. Measurements of streamwise velocity were made to within approximately 120 gm of the model surface. The streamwise spatial resolution in this experiment ranged from 0.6 mm to 2.6 mm. An improvement in the spatial precision of the measurement technique has been made, with spatial uncertainties reduced by about a factor of 2 compared to previous measurements. For the quiescent flow calibration measurements presented, uncertainties as low as 2 m/s are obtained at 95% confidence for long delay times (25 gs). For the velocity measurements obtained with the wind tunnel operating, average single-shot uncertainties of less than 44 m/s are obtained at 95% confidence with a probe laser delay setting of 1 gs. The measurements were performed in the 31-inch Mach 10 Air Tunnel at the NASA Langley Research Center

Specializing Interpreters using Offline Partial Deduction

We present the latest version of the Logen partial evaluation system for logic programs. In particular we present new binding-types, and show how they can be used to effectively specialise a wide variety of interpreters.We show how to achieve Jones-optimality in a systematic way for several interpreters. Finally, we present and specialise a non-trivial interpreter for a small functional programming language. Experimental results are also presented, highlighting that the Logen system can be a good basis for generating compilers for high-level languages