Retrieval Of Aerosol Microphysical Properties From Aeronet Photopolarimetric Measurements, 2015 University of Nebraska-Lincoln
Retrieval Of Aerosol Microphysical Properties From Aeronet Photopolarimetric Measurements, Xiaoguang Xu
Dissertations & Theses in Earth and Atmospheric Sciences
Atmospheric aerosols play an important role in earth climate by scattering and absorbing solar and terrestrial radiation, and indirectly through altering the cloud formation, life- time, and radiative properties. However, accurate quantification of these effects is in no small part hindered by our limited knowledge about the particle size distribution (PSD) and refractive index, the aerosol microphysical properties essentially pertain to aerosol optical and cloud-forming properties. The research goal of this thesis is to obtain the aerosol microphysical properties of both fine and coarse modes from the polarimetric solar radiation measured by the SunPhotometer of the Aerosol Robotic Network (AERONET ...
Simulating Correlated Disorder In Spin Glass, 2015 Macalester College
Simulating Correlated Disorder In Spin Glass, Jared D. Willard
Macalester Journal of Physics and Astronomy
Almost all materials undergo spontaneous symmetry breaking at sufficiently low
temperatures. For most magnetic materials, the spin rotational symmetry is broken
to form magnetic ordering. The discovery of metallic alloys which fail to form
conventional magnetic order has remained a puzzle for the last few decades.
Unfortunately, analytical calculations cannot provide an unbiased answer for the
problem. Furthermore, on the numerical side, Monte Carlo simulations require
extremely long equilibration times. The parallel tempering method has proven a
powerful tool to alleviate the long equilibration time. With the extensive efforts of
numerical simulation research, some of the idealized models have been ...
Extragalactic Explorers: Professors Elizabeth Mcgrath And Dale Kocevski Divine The Mysteries Of The Universe, Gerry Boyle
From their offices on the fourth floor of the Mudd Science Building, Elizabeth McGrath and Dale Kocevski enjoy a view that takes in the terraced lawn of the academic quad, the rooftops of Lovejoy and Cotter Union- and distant galaxies as they appeared when the universe was young.
Rotation Lightcurves Of Small Jovian Trojan Asteroids, 2015 Illinois Wesleyan University
Rotation Lightcurves Of Small Jovian Trojan Asteroids, Linda French, Robert D. Stephens, Daniel Coley, Lawrence H. Wasserman, Jennifer Sieben
Several lines of evidence support a common origin for, and possible hereditary link between, cometary nuclei and Jovian Trojan asteroids. Due to their distance and low albedos, few comet-sized Trojans have been studied. We present new lightcurve information for 19 Trojans ≲ 30 km in diameter, more than doubling the number of objects in this size range for which some rotation information is known. The minimum densities for objects with complete lightcurves are estimated and are found to be comparable to those measured for cometary nuclei. A significant fraction (~40%) of this observed small Trojan population rotates slowly (P > 24 hours ...
Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, 2015 Department of Physics, Utah State University
Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos
Charles G. Torre
Rainich-type conditions giving a spacetime “geometrization” of matter fields in general relativity are reviewed and extended. Three types of matter are considered: perfect fluids, scalar fields, and elec- tromagnetic fields. Necessary and sufficient conditions on a spacetime metric for it to be part of a perfect fluid solution of the Einstein equa- tions are given. Formulas for constructing the fluid from the metric are obtained. All fluid results hold for any spacetime dimension. Ge- ometric conditions on a metric which are necessary and sufficient for it to define a solution of the Einstein-scalar field equations and for- mulas for constructing ...
Detecting Cosmic Rays Using Cemos Sensors In Consumer Devices, 2015 Iowa State University
Detecting Cosmic Rays Using Cemos Sensors In Consumer Devices, Matthew M. Plewa
2015 Academic High Altitude Conference
Since the time of Victor Hess and his balloon flight that demonstrated that cosmic rays increased with altitude, new detection methods have become widely available to be used on current day flights. One such method is to utilize CCDs with long duration exposures. During the exposures the CCD is exposed to cosmic rays which then leave a track. This phenomenon is caused by the CCD's inability to distinguish between photons of light and charged particles. Such tracks can then be separated from the CCD's background noise and classified.
Directional Camera Control On High Altitude Balloons, 2015 Iowa State University
Directional Camera Control On High Altitude Balloons, Matthew M. Plewa, Brent Scharlau
2015 Academic High Altitude Conference
The research reported in this paper examined the design and control of a gimbal for solar eclipse tracking and video recording. The gimbal design required 3 axes of rotation to allow for full range of motion. Utilizing individual brushless motors for each of the axes ensure minimum rotational requirements on each axes. In controlling the gimbal, both a mathematical and visual method were utilized. The mathematical method is a modified version of what is currently used for solar array pointing. The visual method looks at where the position of the sun is within the image and determines what angle changes ...
Cosmic Ray Air Shower Lateral Coincidences, 2015 University of Minnesota, Morris
Cosmic Ray Air Shower Lateral Coincidences, Gordon C. Mcintosh
2015 Academic High Altitude Conference
At the University of Minnesota, Morris, my students and I have begun to investigate the time and altitude dependence of air showers. Air showers are cosmic ray secondaries that spread out laterally around the primary cosmic ray direction. To investigate the air showers we have been measuring the lateral coincidences among three Aware RM60 Geiger counters located at 0 cm, 15 cm, and 40 cm. Most of these measurements have been carried out at the surface. The rate of lateral, triple coincidences of Geiger counter with this configuration is 0.053 ±0.013 hr-1 at the surface. On 4 ...
Models Of Time Travel And Their Consequences, 2015 Oglethorpe University
Models Of Time Travel And Their Consequences, Antonio M. Mantica
Oglethorpe Journal of Undergraduate Research
How do we travel through time? We know that we can move forward in it (we have no choice), but can we jump forward in time? Can we go backward in time? It also gives rise to other troubling questions: is time measurable in distinct increments, or does it flow continuously? In "Models of Time Travel and their Consequences," Antonio Mantica walks the reader through current understandings of how time functions in Einstein's universe and proposes three distinct models to explain it. Following that, he provides a list of experiments to credit or discredit the models. Appropriate for audiences ...
Optimization Of A Solar Simulator For Planetary-Photochemical Studies, 2015 University of Paris 11, Orsay
Optimization Of A Solar Simulator For Planetary-Photochemical Studies, Et-Touhami Es-Sebbar, Yves Bénilan, Nicolas Fray, Hervé Cottin, Antoine Jolly, Marie-Claire Gazeau
Dr. Et-touhami Es-sebbar
Low-temperature microwave-powered plasma based on hydrogen and hydrogen with noble gas mixtures are widely used as a continuous vacuum ultraviolet (VUV) source in laboratory experiments carried out to mimic the photochemistry in astrophysical environments. In this work, we present a study dedicated to optimizing such sources in terms of mono-chromaticity at Lyα (H(Lyα) line at 121.6 nm ~ 10.2 eV) and high spectral irradiance. We report the influence on the emission spectrum of a wide range of experimental conditions including gas composition (pure H2, pure He, and H2/He mixture), gas pressure, flow rates, and microwave power. The ...
Determining The Relationship Between The [Oiii] 5007 Å Emission Line Profile And The Stellar Velocity Dispersion In Active Galaxies, 2015 California Polytechnic State University - San Luis Obispo
Determining The Relationship Between The [Oiii] 5007 Å Emission Line Profile And The Stellar Velocity Dispersion In Active Galaxies, Nathaniel Milgram
The empirical relation between the stellar velocity dispersion (SVD) of the bulge and the mass of the central supermassive black hole (BH) suggests a link between host galaxy and BH evolution. For active galactic nuclei (AGNs), the BH mass (MBH) can be estimated in a straightforward way from the Doppler broadening of the broad emission lines using the so-called virial method. However, the powerful AGN continuum emission often outshines the underlying stellar absorption lines, making it difficult to measure SVD of the host galaxy. Thus, the MBH - SVD relation is difficult to establish for galaxies containing AGNs. As a remedy ...
Frequency Of Seyfert Type Transitions In A Sample Of 102 Local Active Galactic Nuclei, 2015 California Polytechnic State University - San Luis Obispo
Frequency Of Seyfert Type Transitions In A Sample Of 102 Local Active Galactic Nuclei, Jordan Runco
A sample of ∼100 type-1 local (0.02 ≤ z ≤ 0.1) active galaxies (AGNs) was selected from the Sloan Digital Sky Survey with black hole masses MBH > 107 Mʘ and re-observed using the Keck 10-m telescope to study the local scaling relations between MBH and the host galaxy properties. As a side product, the data provides insight into any changes of the broad-line region within the 3-9 year time-frame covered by the two sets of spectra. The variability of the broad Hβ emission line is of particular interest to us, not only because it is used ...
Search For Life, 2015 University at Albany, State University of New York
Search For Life, John W. Delano Phd
Atmospheric and Environmental Science Faculty Scholarship
NASA's Astrobiology program seeks to determine the origin and distribution of life in the Milky Way galaxy using scientific expertise from many disciplines (e.g., astronomy, biochemistry, geochemistry). This presentation, which provides an overview of the progress that has been made in this effort, was delivered on 23 June 2015 at the Green Mountain Academy for Lifelong Learning in Manchester, VT. With NASA's development of the Space Launch System (SLS), vigorous multi-disciplinary scientific research, and additional spacecraft (e.g., TESS) for finding and analyzing planets orbiting other stars, exciting discoveries will continue.
Analysis And Comparison Of Physical Properties And Morphology Of Impact Melt Flows On Venus And The Moon To Determine Atmospheric Controls, Christine Elizabeth Dong
Impact melt flows form when target material melted by an impact breaches the rim of the impact crater. The melt flows out and away from the crater, forming a lava flow. Such flows have been identified on Venus and the Moon by previous studies. This study aims to document impact melt flows on these two bodies to determine the differences, if any, between them, and to ascertain whether these differences are due to atmospheric conditions. Previously recorded morphological data from Robert Herrick of the Lunar and Planetary Institute and Neish et al. (2014) are used in conjunction with S-band (12 ...
Defining The Circumstellar Habitable Zone, 2015 DePaul University
Defining The Circumstellar Habitable Zone, Blake Cervetti, Joanna Mccall
The study of habitable exoplanets is a rapidly expanding ﬁeld in astronomy. Exoplanets are planets that orbit stars other than our own sun. One of the keys to knowing whether or not an exoplanet is habitable is by studying the circumstellar habitable zone, or CHZ. Over the past several years, the deﬁned limits of the CHZ have become susceptible to change as new parameters and factors are found to aﬀect a planets habitability. There are many factors that aﬀect its habitability, including the composition of the star, the mass of the planet, the planets atmosphere, etc. Our focus is divided ...
Detection Of Baryonic Acoustic Oscillations In The Matter Power Spectrum, 2015 DePaul University
Detection Of Baryonic Acoustic Oscillations In The Matter Power Spectrum, Spencer Everett, Ian Johnson, Jon Murphy, Mary Tarpley
Using the spectra of 22,923 high-redshift quasars from the Baryon Oscillation Spectrosocpic Survey (BOSS) subset of the Sloan Digital Sky Survey (SDSS), the authors detect evidence of the primordial baryonic acoustic oscillations (BAOs) in the matter power spectrum. The detection further endorses the currently accepted Lambda-CDM model of cosmology based upon the existence of dark energy (Lambda) and cold dark matter (CDM). Additionally, the use of the continuous wavelet transform to calculate the power spectrum has many advantages over traditional Fourier methods and independently corroborates previous detections.
Ultrafast Photoconductivity Measurements Of A Thermoelectric Nanocomposite: Tellurium Nanowire/Pedot:Pss, Brittany A. Ehmann
Macalester Journal of Physics and Astronomy
This project explores the conductivity properties of a novel thermoelectric hybrid material (Tellurium nanowires in a conducting polymer PEDOT:PSS) using both static and time-resolved conductivity measurements. We find that the effect of the conducting polymer PEDOT is weak and that the observed differences in conductivity measurements between the hybrid and non-hybrid material are most likely caused by the different sizes of the nanowires.
Multidimensional Simulations Of Non-Linear Cosmic Ray Production In Supernova Remnant Evolution, 2015 Clemson University
Multidimensional Simulations Of Non-Linear Cosmic Ray Production In Supernova Remnant Evolution, Joshua Wood
When a high-mass star (& 4Msun) explodes at the end of its life, a supernova occurs, leaving its degenerate core and a fast-moving shell of matter, known as a supernova remnant (SNR). The SNR shell lasts for many thousands of years, generating emissions from low-frequency radio (~ 10-7 eV) up to γ-ray regime (~ 1015 eV). It is also believed that SNRs are the predominant source of galactic cosmic rays, accelerating a population of thermal ions, primarily protons, up to relativistic energies by means of the diffusive shock acceleration (DSA) mechanism. The small population of thermal (Boltzmann) particles, p ~ 10-3 eV, that are accelerated to relativistic energies, p ~ 1015 eV, extract a significant amount of energy from the SNR shell. The existence of a small but highly energetic population of non-thermal particles feeds back into the dynamic evolution of the SNR, which, in turn, affects the production of new particles and the continued acceleration of particles already swept up in the shock. Much research has been done in investigating the case of particles accelerated in spherically symmetric SNRs; we present here the first simulations of supernova remnant evolution with nonlinear cosmic ray feedback in multiple dimensions. The research here presents a new approach to an old problem, allowing for a deeper investigation into the role of cosmic ray production in supernova remnant environments. The findings here show that, at the early stages of SNR evolution, the presence of cosmic rays in the shocks modifies the growth of hydrodynamic instabilities; severely damping the Rayleigh-Taylor instabilities in particular. We also find that the young remnant produces a strong TeV population of CRs that can generate TeV ...
Topics In Broadband Gravitational-Wave Astronomy, 2015 University of Wisconsin-Milwaukee
Topics In Broadband Gravitational-Wave Astronomy, Sydney Joanne Chamberlin
Theses and Dissertations
The direct detection of gravitational waves promises to open a new observational window onto the universe, and a number of large scale efforts are underway worldwide to make such a detection a reality. In this work, we attack some of the current problems in gravitational-wave detection over a wide range of frequencies.
In the first part of this work, low frequency gravitational-wave detection is considered using pulsar timing arrays (PTAs). PTAs are a promising tool for probing the universe through gravitational radiation. Supermassive black hole binaries (SMBHBs), cosmic strings, relic gravitational waves from inflation, and first order phase transitions in ...
Self-Force On Accelerated Particles, 2015 University of Wisconsin-Milwaukee
Self-Force On Accelerated Particles, Thomas Michael Linz
Theses and Dissertations
The likelihood that gravitational waves from stellar-size black holes spiraling into a supermassive black hole would be detectable by a space based gravitational wave observatory has spurred the interest in studying the extreme mass-ratio inspiral (EMRI) problem and black hole perturbation theory (BHP). In this approach, the smaller black hole is treated as a point particle and its trajectory deviates from a geodesic due to the interaction with its own field. This interaction is known as the gravitational self-force, and it includes both a damping force, commonly known as radiation reaction, as well as a conservative force. The computation of ...