6,636 Works

Models of bottom-up and top-down visual attention

Laurent Itti
When we observe our visual environment, we do not perceive all its components as being equally interesting. Some objects automatically and effortlessly "pop out" from their surroundings, that is, they draw our visual attention, in a "bottom up" manner, towards them. In a first approximation, focal visual attention acts as a rapidly shiftable "spotlight," which allows only the selected information to reach higher levels of processing and representation. Most models of the bottom-up control of...

Galaxy Formation Near the Epoch of Reionization

Michael Robert Santos
I present five explorations of the formation of early galaxies near the epoch of reionization: observable phenomena that demonstrate the interaction between galaxy formation and the intergalactic medium. I calculated the contribution of the first stars (Pop III) to the cosmic infrared background (CIRB). Pop III stars produced the observed unexplained component of the NIR CIRB if they were very massive and formed efficiently over a redshift range 25 ≳ z ≳ 7. A small...

Contribution of the Temporoammonic Pathway to Hippocampal Processing

Hannah Dvorak-Carbone
The temporoammonic (TA) pathway is the direct, monosynaptic projection from layer III of entorhinal cortex to the distal dendritic region of area CA1 of the hippo­ campus. Although this pathway has been implicated in various functions, such as memory encoding and retrieval, spatial navigation, generation of oscillatory activity, and control of hippocampal excitability, the details of its physiology are not well understood. In this thesis, I examine the contribution of the TA pathway to hippocampal...

The Pacoima Area

Robert Lloyd Fisher
The Pacoima area consists of Miocene (sediments and basalts) rocks underlain by a quartz diorite basement complex of Jurassic age. The stratigranhic units range from 25 feet to more than 600 feet in thickness. The lower sediments are arkosic land- laid deposits while the Modelo formation, shallow marine in origin, consists of thinly bedded sandstones, shales, volcanic ash and calcareous members. An andesitic mass, possibly a volcanic plug, outcrops near the summit of one of...

The influences of stress and temperatures upon the time to initiate plastic deformation in an annealed low carbon steel

David Shotwell Wood
An experimental investigation of the time delay for initiation of plastic deformation in an annealed low carbon steel is described. The delay time is determined as a function of the applied stress at temperatures of -75°F, 73°F, 150°F, and 250°F. The stress is applied in a continuous manner within a period of about 7 millisec, and the stress is maintained substantially constant thereafter, until plastic deformation begins. At any given temperature, the relation between the...

Experiments on Mixing and Combustion with Low Heat Release in a Turbulent Shear Flow

Mark Godfrey Mungal
A new blowdown facility to study mixing and combustion in a turbulent shear layer has been built. The system is capable of 100 m/s for three seconds in a 5 x 20 cm exit area on the high speed side, and 50 m/s in a 10 x 20 cm exit area on the low speed side. Dilute concentrations of hydrogen and fluorine, carried in an inert gas, react when both fluid streams meet at the...

A study of the boron trifluoride complexes of some carotenoid hydrocarbons and the products of their hydrolytic and alcoholytic cleavage

Warren Van Ness Bush
Formation of a deeply-colored [alpha]-carotene - boron trifluoride complex, by means of boron trifluoride etherate, and subsequent hydrolysis of the complex result mainly in the formation of 4-hydroxy-[alpha]-carotene, indicating that, under the conditions applied, only the [beta]-ionone end of the complex is reactive; ethanolysis gave the corresponding ethoxy derivative. The structures of these two compounds and some of the other reaction products were clarified. On this basis the structure of the BF3-complex has also been...

Response of soil mineral weathering to elevated carbon dioxide

Jennie Catherine Stephens
Understanding the rates of weathering of soil minerals and the factors that may either enhance or inhibit these rates is a crucial part of understanding many processes from the watershed to the global scale. One potentially important factor in mineral weathering that is not yet well understood is the effect of elevated CO2 concentrations on weathering rates. Here, the direct and indirect effects of elevated soil CO2 are examined in field and laboratory-based studies, and...

On nucleic acid photochemistry

Daniel Lewis Wulff
I. Frozen aqueous solutions of thymine and N, N'-dimethylthymine have been irradiated at 2537 Å to yield two dimers from N,N'-dimethylthymine and a single dimer from thymine. In all cases irradiation of the dimer in liquid aqueous solution at 2537 Å causes reversion to the monomer. One of the photodimers obtained from N,N'-dimethylthymine is identical to a product obtained by exhaustively N–methylating the single photodimer obtained from thymine. Nuclear magnetic resonance and ultraviolet absorption data...

Least square polynomial spline approximation

Paul David Patent
Bounds are derived for both the L2- and L∞-norms of the error in approximating sufficiently smooth functions by polynomial splines using an integral least square technique based on the theory of orthogonal projection in real Hilbert space. Quadrature schemes for the approximate solution of this least square problem are examined and bounds for the error due to the use of such schemes are derived. The question of the consistency of such quadrature schemes with the...

The stellar composition and evolution of irregular and other late-type galaxies

William G. Bagnuolo
The stellar content and history of star formation of a number of Irregular and other late-type galaxies have been analyzed by means of 10-color photometery of the galaxies and a comparison of their colors to the calculated colors of a set of three-parameter models. The galaxy models are assumed to be composed of various amounts of "clusters" from 10[superscript 6] to 10[superscript 10] years old, the colors of which were calculated from stellar-evolutionary tracks and...

Volcanic tuff beds of the Mint Canyon formation

Robert Earl Wallace
The Mint Canyon formation (Upper Miocene) consists of a series of continental sediments including both fanglomerates and fresh-water lake deposits. The basin of deposition of the lake sediments was near the sea but was apparently definitely separated from it. Some 4000 or more feet of sediments have accumulated. The Mint Canyon formation lies nonconformably above the Vasquez formation (Oligocene?). The angular discordance between the Mint Canyon formation and the overlying Modelo (Upper Miocene) is not...

Persistent holographic storage in photorefractive crystals

Ali Adibi
The work presented in this thesis has been focused on solving the most important and long-lasting problem of destructive read-out in holographic recording in photorefractive crystals. Several interesting methods for solving this problem were proposed and demonstrated by researchers for more than two decades. However, none of them were practical for read / write applications. The most promising all-optical method, which is still being pursued by some researchers, was two-step recording. However, the method suffers...

Photoproduction of K° mesons from carbon : a freon bubble chamber experiment

Ethan Davidson Alyea
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The feasibility of utilizing characteristic interactions of K2° mesons in the liquid of a CF3Br bubble chamber for the purpose of detecting photoproduced K° mesons has been investigated. The K2° mesons were produced from carbon at an average laboratory angle of 11 degrees by photons with energies ranging from threshold to 1300 Mev. Although examples of...

Some effects of secondary injection of gases into a supersonic flow

Harvey Worth Burden
An experimental investigation was conducted in order to determine some of the effects of injection of a secondary stream of gas into a supersonic primary airstream. The flow fields behind an orifice producing essential two-dimensional flow and behind that producing full three-dimensional flow were studied. The resulting shock patterns, wall static pressure profiles, and flow field characteristics are described,and use is made of a theoretical injectant penetration height to non-dimensionalize the results as much as...

Absorption and dispersion of sound in reacting and relaxing fluids

William Phillip Helman
The hydrodynamic equations for a chemically reacting and internally relaxing fluid are obtained in a suitable form, and, are then used to find the dispertion and absorption of plane infinitesimal sound waves, Only the case of no viscosity, heat conduction, and diffusion is considered. It is shown that the interference effects between relaxation processes are not, in general, negligible compared to the relaxation effects themselves. A specific example, that of oxygen gas at 2500° K...

The statistical bootstrap model

Christopher John Hamer
A review is presented of the statistical bootstrap model of Hagedorn and Frautschi. This model is an attempt to apply the methods of statistical mechanics in high-energy physics, while treating all hadron states (stable or unstable) on an equal footing. A statistical calculation of the resonance spectrum on this basis leads to an exponentially rising level density ρ(m) ~ cm-3 eβom at high masses. In the present work, explicit formulae are given for the asymptotic...

Wind-driven desertification: process modeling, remote monitoring, and forecasting

Gregory Stewart Okin
Arid and semiarid landscapes comprise nearly a third of the Earth's total land surface. These areas are coming under increasing land use pressures. Despite their low productivity these lands are not barren. Rather, they consist of fragile ecosystems vulnerable to anthropogenic disturbance. The purpose of this thesis is threefold: (I) to develop and test a process model of wind-driven desertification, (II) to evaluate next-generation process-relevant remote monitoring strategies for use in arid and semiarid regions,...

Theory, fabrication and performance of some integrated optical devices

Sasson R. Somekh
Recent progress in the fabrication of low attenuation optical fibers raises the attractive possibility of optical communications via these waveguides. Integration of different optical functions on one substrate in the form of optical circuits will form ideal terminals for such a communication network. We shall discuss the theory, fabrication and performance of a few "building stones" of such optical circuits. Optical directional couplers capable of coupling light from one channel to another will be described...

Supersonic flow through cascades, with application to diffusers

Rolf Dietrich Buhler
Supersonic flow through a two-dimensional cascade of airfoils is discussed from the point of view of one-dimensional gas dynamics. Two generalizations to compressible flow of the usual velocity vector diagrams are discussed, namely the Mach vector and the reduced velocity vector diagram. A relative mass flow parameter is found which represents the isentropic continuity equation on the two vector diagrams, so that for a set of given cascade inlet conditions all possible outlet velocities and...

Stationary Subdivision and Multiresolution Surface Representations

Denis N. Zorin
Stationary subdivision is an important tool for generating smooth free-form surfaces used in CAGD and computer graphics. One of the challenges in the construction of subdivision schemes for arbitrary meshes is to guarantee that the surfaces produced by the algorithm are C1-continuous. First results in this direction were obtained only recently. In this thesis we derive necessary and sufficient criteria for Ck-continuity that generalize and extend most known conditions. We present a new method for...

Preparation and characterization by streaming birefringence of sodium desoxyribonucleate

Jerome Marshall Hershman
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Three preparations of the sodium salt of desoxyribonucleic acid were isolated from calf thymus by a method expected to give minimal or no depolymerization. In addition, preparations were made from calf spleen and bull testis tissues. Streaming birefringence measurements indicate that the distributions of molecular length are identical in the calf thymus preparations. The apparent molecular...

Dynamic stability of cylindrical shells under step loading

Yukio Stephen Tamura
A study has been made to determine the dynamic stability of an imperfect circular cylindrical shell subject to a step loading in the axial direction. In the analysis, the radial displacement of the shell is approximated by a finite degree of freedom system. To assure that the created model is proper, its static buckling behavior was studied. It was found that the model gives the proper imperfection sensitivity behavior. The dynamic analysis includes not only...

The brachiopod fauna of the Arisaig series (Silurian-Lower Devonian) of Nova Scotia

Charles W. Harper
The Arisaig series comprises a very fossiliferous, fairly continuous sequence of strata of early Llandovery to Gedinnian age. The brachiopod species of the Arisaig series are described, identified generically, and compared with related species. Forty-five genera and eighty-two species are recognized. Seven new species, three new genera, and three new subgenera are proposed. A phylogeny is proposed for each of the following groups: the Rhipidomellidae, plagiorhynchids, leptostrophids, douvillinids, and the Pholidostrophiinae. Idiorthis is considered to...

Signal Integrity Issues in High-Speed Wireline Links: Analysis and Integrated System Solutions

Behnam Analui
This work focuses on the basic signal integrity issues of high-speed wireline links. It bridges the gap between optimum system design and circuit design for such links by: (1) understanding the effects of the system parameters on the bit error rate (BER), (2) introducing circuit architectures for the realization of systems that minimize the BER, and (3) demonstrating integrated circuit prototypes that verify the solutions. First, we develop a theory that analytically relates the data...

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  • California Institute of Technology
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  • University of Erlangen-Nuremberg
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