Some High Temperature Diffusion Studies on Materials of Thermionic Interest

High temperature diffusion studies between uranium materials and refractory metals and alloys - thermionic emission propertie

Grid Cells Form a Global Representation of Connected Environments.

The firing patterns of grid cells in medial entorhinal cortex (mEC) and associated brain areas form triangular arrays that tessellate the environment [1, 2] and maintain constant spatial offsets to each other between environments [3, 4]. These cells are thought to provide an efficient metric for navigation in large-scale space [5-8]. However, an accurate and universal metric requires grid cell firing patterns to uniformly cover the space to be navigated, in contrast to recent demonstrations that environmental features such as boundaries can distort [9-11] and fragment [12] grid patterns. To establish whether grid firing is determined by local environmental cues, or provides a coherent global representation, we recorded mEC grid cells in rats foraging in an environment containing two perceptually identical compartments connected via a corridor. During initial exposures to the multicompartment environment, grid firing patterns were dominated by local environmental cues, replicating between the two compartments. However, with prolonged experience, grid cell firing patterns formed a single, continuous representation that spanned both compartments. Thus, we provide the first evidence that in a complex environment, grid cell firing can form the coherent global pattern necessary for them to act as a metric capable of supporting large-scale spatial navigation

Massive Protoplanetary Disks in the Trapezium Region

(abridged) We determine the disk mass distribution around 336 stars in the young Orion Nebula cluster by imaging a 2.5' x 2.5' region in 3 mm continuum emission with the Owens Valley Millimeter Array. For this sample of 336 stars, we observe 3 mm emission above the 3-sigma noise level toward ten sources, six of which have also been detected optically in silhouette against the bright nebular background. In addition, we detect 20 objects that do not correspond to known near-IR cluster members. Comparisons of our measured fluxes with longer wavelength observations enable rough separation of dust emission from thermal free-free emission, and we find substantial dust emission toward most objects. For the ten objects detected at both 3 mm and near-IR wavelengths, eight exhibit substantial dust emission. Excluding the high-mass stars and assuming a gas-to-dust ratio of 100, we estimate circumstellar masses ranging from 0.13 to 0.39 Msun. For the cluster members not detected at 3 mm, images of individual objects are stacked to constrain the mean 3 mm flux of the ensemble. The average flux is detected at the 3-sigma confidence level, and implies an average disk mass of 0.005 Msun, comparable to the minimum mass solar nebula. The percentage of stars in Orion surrounded by disks more massive than ~0.1 Msun is consistent with the disk mass distribution in Taurus, and we argue that massive disks in Orion do not appear to be truncated through close encounters with high-mass stars. Comparison of the average disk mass and number of massive dusty structures in Orion with similar surveys of the NGC 2024 and IC 348 clusters constrains the evolutionary timescales of massive circumstellar disks in clustered environments.Comment: 27 pages, including 7 figures. Accepted by Ap

The synthesis of 15 mu infrared horizon radiance profiles from meteorological data inputs

Computational computer program for modeling infrared horizon radiance profile using pressure and temperature profile input

Studies of thermionic materials for space power applications informal monthly report, sep. 1 - sep. 30, 1963

Thermionic materials for space power application - uranium carbide-zirconium carbide fuels and tungsten claddin

Corral systems for handling and sorting hogs (1993)

Construction of semi-confinement feeding floors for swine has increased in recent years. Available plans concentrate on design of the confinement area and feed handling. As producers expand, they need more efficient ways to sort, handle and load hogs. Additional planning is required to design smooth flow patterns for livestock handling into the basic production unit

Detection of s-Triazine pesticides in natural waters by modified large-volume direct injection HPLC

There is a need for simple and inexpensive methods to quantify potentially harmful persistent pesticides often found in our water-ways and water distribution systems. This paper presents a simple, relatively inexpensive method for the detection of a group of commonly used pesticides (atrazine, simazine and hexazinone) in natural waters using large-volume direct injection high performance liquid chromatography (HPLC) utilizing a monolithic column and a single wavelength ultraviolet–visible light (UV–vis) detector. The best results for this system were obtained with a mobile phase made up of acetonitrile and water in a 30:70 ratio, a flow rate of 2.0 mL min−1, and a detector wavelength of 230 nm. Using this method, we achieved retention times of less than three minutes, and detection limits of 5.7 μg L−1 for atrazine, 4.7 μg L−1 for simazine and 4.0 μg L−1 for hexazinone. The performance of this method was validated with an inter-laboratory trial against a National Association of Testing Authorities (NATA) accredited liquid chromatography–mass spectrometry/mass spectrometry (LC–MS/MS) method commonly used in commercial laboratories

A new vlf phenomenon- whistlers trapped below the protonosphere

Very low frequency whistler trapped below protonosphere identified through ground station measurements on Aerobee rocket and Alouette satellit