10,456 Works

Spectroscopy and Kinetics of Atmospheric and Astrochemical Reactions

Joseph Peter Herman Messinger
The reactions between reactive radicals and other neutral compounds have long been known to be important in atmospheric chemistry and astrochemistry. This work uses pulsed-laser photolysis cavity ringdown spectroscopy and laser-induced fluorescence to measure the rate constants and branching ratios of chemical reactions over a wide range of temperatures and pressures relevant to both polluted atmospheres, and the interstellar medium. This includes studying the OH + NO₂ reaction in the 253 – 333 K range,...

Non-Covalent Interactions in Aqueous Media: Molecular Recognition Studies Through Circular Dichroism and Self-Assembly of Discrete Aggregates

Jonathan Eric Forman
The application of circular dichroism (CD) spectroscopy to the study of molecular recognition phenomena in chiral water-soluble cyclophane hosts is described. The CD method produces results that complement and expand upon previous NMR studies. This includes allowing the measurement of larger binding constants by allowing studies to be carried out at lower concentrations. Using the excitonic chirality method, these studies have provided a means of assigning the absolute stereochemistry of the ethenoanthracene building blocks used...

Data from: Gut microbiota regulate motor deficits and neuroinflammation in a model of Parkinson’s disease

Timothy R. Sampson, Justine W. Debelius, Taren Thron, Stefan Janssen, Gauri G. Shastri, Zehra Esra Ilhan, Collin Challis, Catherine E. Schretter, Sandra Rocha, Viviana Gradinaru, Marie-Francoise Chesselet, Ali Keshavarzian, Kathleen M. Shannon, Rosa Krajmalnik-Brown, Pernilla Wittung-Stafshede, Rob Knight & Sarkis K. Mazmanian
The intestinal microbiota influence neurodevelopment, modulate behavior, and contribute to neurological disorders. However, a functional link between gut bacteria and neurodegenerative diseases remains unexplored. Synucleinopathies are characterized by aggregation of the protein α-synuclein (αSyn), often resulting in motor dysfunction as exemplified by Parkinson’s disease (PD). Using mice that overexpress αSyn, we report herein that gut microbiota are required for motor deficits, microglia activation, and αSyn pathology. Antibiotic treatment ameliorates, while microbial re-colonization promotes, pathophysiology in...

Data from: A double-sided microscope to realize whole-ganglion imaging of membrane potential in the medicinal leech

Yusuke Tomina & Daniel A Wagenaar
Studies of neuronal network emergence during sensory processing and motor control are greatly promoted by technologies that allow us to simultaneously record the membrane potential dynamics of a large population of neurons in single cell resolution. To achieve whole-brain recording with the ability to detect both small synaptic potentials and action potentials, we developed a voltage-sensitive dye (VSD) imaging technique based on a double-sided microscope that can image two sides of a nervous system simultaneously....

Data from: Evolution and Phylogeny of the Diptera: A Molecular Phylogenetic Analysis Using 28S rDNA Sequences

Markus Friedrich & Diethard Tautz
Portions of the large ribosomal subunit RNA gene (28S rDNA) encompassing the D1 and the D7 region were obtained from 16 dipteran species and families to reconstruct early phylogenetic events in the order Diptera. For outgroup comparison, the corresponding sequences were used from representative taxa of the Siphonaptera, Mecoptera, and Lepidoptera. A subset of 488 unambiguously alignable sites was analyzed with respect to important sequence evolution parameters. We found (1) sequence variability is significantly higher...

Cooperative Oligonucleotide-Directed Triple Helix Formation at Adjacent DNA Sites

Natalia Colocci
Cooperative interactions between DNA-binding ligands are essential for their sequence specificity, binding affinity, and biological activity. Oligonucleotides can bind cooperatively to adjacent sites on double-helical DNA by triple helix formation. The study of the cooperative binding of oligonucleotides to DNA by triple helix formation is important as it provides useful information for the development of new methods leading to the sequence-specific recognition of DNA. As a first step towards this goal, the thermodynamics of the...

Berkeley High Resolution (BEHR) OMI NO2 v3.0C - Gridded pixels, daily profiles

Qindan Zhu, Joshua Laughner & Ron Cohen
The BEHR reprocesses tropospheric NO2 columns from the Ozone Monitoring Instrument (OMI) satellite using high resolution a priori NO2 profiles, surface reflectivity, and surface elevation data. This product uses NO2 profiles for the day retrieved, simulated by the WRF-Chem model at 12 km spatial resolution. The use of high spatial resolution NO2 profiles has been shown to better resolve urban/rural differences in NO2 column densities, and the use of day-to-day (rather than monthly average) profiles...

Investigations of the aerodynamic interactions between wind tunnel models and their support systems at the GALCIT ten foot wind tunnel

Josiah E. Smith
This work is divided into two parts. Part I describes the GALCIT image system tare procedure as it is used at the present time, the techniques of operation, and the assumptions used. The tare procedure is an experimental method for obtaining the aerodynamic interference forces and moments produced on a wind tunnel model by the supporting structure which holds it fixed in the windstream. The present technique has been in use at GALCIT for over...

Low speed wind tunnel investigation of high lift devices on a 65 degree swept-back supersonic wing of 3.44 aspect ratio

Michael F. Marx
A low speed survey was conducted on a 3.44 aspect ratio wing having a 65° swept-back leading edge and double wedge symmetrical airfoil section to obtain information as to the effectiveness of various high-lift devices. These devices included trailing edge split and extended split flaps, leading edge split flaps, slats and combined configurations. Tests were carried out on the wing with and without the fuselage and horizontal tail surface. The split flaps increased the lift...

Kinetics and Stereochemistry of the Hydrolysis of Esters of Nitric, Sulfuric and p-Toluenesulfonic Acids

Pierre Jean Leroux
Unlike the hydrolysis of carboxylic esters or that of alkyl halides, the hydrolysis of esters derived from oxygenated acids of nitrogen, phosphorus, sulfur and the halogens has not been subjected to a systematic investigation. This work represents an attempt to clarify the mechanism operating in the hydrolysis of alkyl sulfonates, sulfates and nitrates. 2-Butanol and 2,3-butanediol were chosen as the alcoholic constituents because they afforded easily obtainable optical isomers and also because of their intermediate...

Studies on Radula Tooth Mineralization in the Polyplacophora

Michael Harvey Nesson
This report is concerned with several aspects of the process of iron mineralization of the radula teeth of chitons (Polyplacophora. In Part I, the cusp cells of the radula sac, which are responsible for the deposition of iron into the major lateral teeth, are studied with the electron microscope. In Mopalia muscosa and Lepidochitona (Cyanoplax) hartwegi, it is found that these cells extend from a dorsal blood sinus to the surface of the teeth. The...

Throughput Optimization of Quasi Delay Insensitive Circuits via Slack Matching

Piyush Prakash
Though the logical correctness of an asynchronous circuit is independent of implementation delays, the cycle time of an asynchronous circuit is of great importance to the designer. Oftentimes, the insertion of buffers to such circuits reduces the cycle time of the circuit without affecting the logical correctness of the circuit. This optimization is called slack matching. In this thesis the slack matching problem is formulated. I show that this problem is NP-complete via a reduction...

The thickness effect and plastic flow in cracked plates

Jerold Lindsay Swedlow
Over a range of plate thickness, it is well known that the fracture behavior of flat plates is substantially different from that predicted by classical fracture analyses. Finiteness of the plate thickness causes a variety of failure mechanisms to occur, and qualitative features of the associated stress and strain fields may be deduced. It is indicated that both the three-dimensional nature of the stress field and the plastic deformations will be needed for an accurate...

Low Temperature Photoluminescence Properties of Silicon and Silicon-Germanium Alloys

Gordon Stuart Mitchard
In this thesis, three examples of the application of the photoluminescence technique to indirect semiconductors at low temperatures are presented. Chapter 2 deals with the effect of increasing impurity concentrations on the photoluminescence spectrum. We present results for the Si:(B,In) system. As the In concentration is increased, we observe quenching of B luminescence. We propose a model based on exciton transfer from B to In impurities, which agrees well with the experimental results when the...

Analysis of Neuronal Dynamics in Behaving Animals

Bijan Pesaran
This thesis presents a set of mathematical techniques for analyzing neural activity and then applies them to data from a variety of experiments. Imaging data, in which movies of brain activity are recorded, is considered first and ways to suppress noise and characterize the signal are explored. Data from the cortex of behaving monkeys is then considered. These techniques are used to analyze the activity of populations of neurons during eye movements. Oscillations are found...

Work hardening during pyramidal slip in zinc

Nazeer Ahmed
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The elastic stress field and energy associated with an infinite straight edge dislocation in a hexagonal crystal parallel to the line of intersection of the (0001) and the [...] planes with its Burger's Vector in the [...] plane and the [...] direction is determined taking into account the anisotropy of the crystal. The nature of the...

Microscopic Behavior of Internet Congestion Control

Xiaoliang (David) Wei
The Internet research community has focused on the macroscopic behavior of Transmission Control Protocol (TCP) and overlooked its microscopic behavior for years. This thesis studies the microscopic behavior of TCP and its effects on performance. We go into the packet-level details of TCP control algorithms and explore the behavior in short time scales within one round-trip time. We find that the burstiness effects in such small time scales have significant impacts on both delay-based TCP...

On Numerical Boundary Conditions for the Navier-Stokes Equations

Michael John Naughton
Part I: We consider the numerical solution of the Navier-Stokes equations governing the unsteady flow of a viscous incompressible fluid. The analysis of numerical approximations to smooth nonlinear problems reduces to the examination of related linearized problems. The well posedness of the linear Navier-Stokes equations and the stability of finite difference approximations are studied by making energy estimates for the initial boundary value problems. Flows with open boundaries (i.e., inflow and outflow) and with solid...

A quantitative examination of the buoyancy behavior of macromolecules of known molecular weight in a density gradient at equilibrium in the ultracentrifuge

James Brown Ifft
The quantitative aspects of the method of sedimentation equilibrium in a density gradient with a purified protein of known molecular weight have been examined. In order to quantitatively evaluate the results of density gradient experiments, the density distribution and the density gradient in the salt solution at equilibrium in the ultracentrifuge must be known. Calculations based on thermodynamic data were made to determine these quantities. The results of this work are given in Part I....

A mathematical framework for discussing the statistical distribution of galaxies in space and its cosmological implications

J. E. Gunn
The spectral-theoretic techniques of stationary time-series analysis are generalized and applied to the study of the statistical distribution of galaxies in space and the observed distribution on the sky. Sampling techniques and criteria are developed for the measurement of the Fourier transform of the autocovariance function, the so-called "power spectrum". The theory is extended to curved, nonstatic space-times and the possibility of using the spectral density obtained from counts of galaxies in the formulation of...

I. Cardiovascular fluid mechanics. II. Fluid dynamics of prosthetic aortic valves. III. Use of the fast Fourier transform in the analysis of cardiovascular sounds

A. P. Yoganathan
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Pressure drops across ten prosthetic aortic heart valves have been measured under both steady and pulsatile flow using two different Newtonian liquids having viscosities of 0.01 dyne sec/cm[superscript 2] and 0.035 dyne sec/cm[superscript 2], respectively. The experimental results and the theory developed indicate that for a given aortic valve it is possible to predict peak systolic...

Adaptive and diversity techniques for wireless digital communications over fading channels

Mohamed-Slim Alouini
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Demand for mobile and personal communications is growing at a rapid pace, both in terms of the number of potential users and the introduction of new high-speed services. Meeting this demand is challenging since wireless communications are subject to three major constraints: a complex and harsh fading channel, a scarce usable radio spectrum, and limitations on...

Electrical resistance and thermoelectric power of the metastable phases in tellurium-base alloys

Chang-chyi Tsuei
By using techniques of rapid quenching from the melt, metastable phases have been obtained in ternary alloys which contain tellurium as a major component and two of the three noble metals (Cu, Ag, Au) as minor components. The metastable phases found in this investigation are either simple cubic or amorphous. The formation of the simple cubic phase is discussed. The electrical resistance and the thermoelectric power of the simple cubic alloy (Au30Te70) have been measured...

Nuclear Weak Interaction Rates During Stellar Evolution and Collapse

George Michael Fuller
Nuclear weak interaction rates, including electron and positron emission rates, and continuum electron and positron capture rates, as well as the associated ν and ⊽ energy loss rates are calculated on a detailed grid of temperature and density for the free nucleons and 226 nuclei with masses between A = 21 and 60. Gamow-Teller and Fermi discrete-state transition matrix element systematics and the Gamow-Teller T< ⇄ T> resonance transitions are discussed in depth and are...

A Study on the Mechanism of Molecular Transport with Systems of Gaseous Paraffins and of Convective Transport from Single Cylinders, Single Spheres, and Arrays of Spheres into Turbulently Flowing Streams

Terry Randolph Galloway
PART I. Intermolecular pair potential functions for the Leonard-Jones ∞-6, 12-6, and 9-6 form, and of the three parameter forms of Morse and of Kihara for a spherical core, were used to fit new gas phase viscosity data at low pressure for the normal paraffins through n-decane. The intermolecular force parameters were obtained and found to be unique for the Morse and Kihara potentials. All potential models underestimated the temperature dependence of the viscosity, but...

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