Observational and theoretical work towards the separation of foreground emission from the cosmic microwave background is described. The bulk of this work is in the design, construction, and commissioning of the C-Band All-Sky Survey (C-BASS), an experiment to produce a template of the Milky Way Galaxy's polarized synchrotron emission. Theoretical work is the derivation of an analytical approximation to the emission spectrum of spinning dust grains.
\r\n\r\nThe performance of the C-BASS experiment is demonstrated through a preliminary, deep survey of the North Celestial Pole region. A comparison to multiwavelength data is performed, and the thermal and systematic noise properties of the experiment are explored. The systematic noise has been minimized through careful data processing algorithms, implemented both in the experiment's Field Programmable Gate Array (FPGA) based digital backend and in the data analysis pipeline. Detailed descriptions of these algorithms are presented.
\r\n\r\nThe analytical function of spinning dust emission is derived through the application of careful approximations, with each step tested against numerical calculations. This work is intended for use in the parameterized separation of cosmological foreground components and as a framework for interpreting and comparing the variety of anomalous microwave emission observations.
\r\n", "publication_date": "2014", "thesis_type": "phd", "thesis_year": "2014" }, { "id": "thesis:7784", "collection": "thesis", "collection_id": "7784", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05302013-225100503", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 23016889, "license": "other", "mime_type": "application/pdf", "url": "/7784/1/thesis.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "The Relationship Between the Radio and Gamma-Ray Emission of Blazars", "author": [ { "family_name": "Max-Moerbeck Astudillo", "given_name": "Walter Kennerth", "clpid": "Max-Moerbeck-Astudillo-Walter-Kennerth" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Cohen", "given_name": "Judith G.", "orcid": "0000-0002-8039-4673", "clpid": "Cohen-J-G" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Hirata", "given_name": "Christopher M.", "orcid": "0000-0002-2951-4932", "clpid": "Hirata-C-M" }, { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-G" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Blazars are active galaxies with a jet closely oriented to our line of sight. They are powerful, variable emitters from radio to gamma-ray wavelengths. Although the general picture of synchrotron emission at low energies and inverse Compton at high energies is well established, important aspects of blazars are not well understood. In particular, the location of the gamma-ray emission region is not clearly established, with some theories favoring a location close to the central engine, while others place it at parsec scales in the radio jet.
\r\n\r\nWe developed a program to locate the gamma-ray emission site in blazars, through the study of correlated variations between their gamma-ray and radio-wave emission. Correlated variations are expected when there is a relation between emission processes at both bands, while delays tell us about the relative location of their energy generation zones. Monitoring at 15 GHz using the Owens Valley Radio Observatory 40 meter telescope started in mid-2007. The program monitors 1593 blazars twice per week, including all blazars detected by the Fermi Gamma-ray Space Telescope (Fermi) north of -20 degrees declination. This program complements the continuous monitoring of gamma-rays by Fermi.
\r\n\r\nThree year long gamma-ray light curves for bright Fermi blazars are cross-correlated with four years of radio monitoring. The significance of cross-correlation peaks is investigated using simulations that account for the uneven sampling and noise properties of the light curves, which are modeled as red-noise processes with a simple power-law power spectral density. We found that out of 86 sources with high quality data, only three show significant correlations (AO 0235+164, B2 2308+34 and PKS 1502+106). Additionally, we find a significant correlation for Mrk 421 when including the strong gamma-ray/radio flare of late 2012. In all four cases radio variations lag gamma-ray variations, suggesting that the gamma-ray emission originates upstream of the radio emission. For PKS 1502+106 we locate the gamma-ray emission site parsecs away from the central engine, thus disfavoring the model of Blandford and Levinson (1995), while other cases are inconclusive. These findings show that continuous monitoring over long time periods is required to understand the cross-correlation between gamma-ray and radio-wave variability in most blazars.
", "doi": "10.7907/ZX5X-V114", "publication_date": "2013", "thesis_type": "phd", "thesis_year": "2013" }, { "id": "thesis:6945", "collection": "thesis", "collection_id": "6945", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04182012-140409324", "primary_object_url": { "basename": "richards_joseph_l_2012_thesis.pdf", "content": "final", "filesize": 10085683, "license": "other", "mime_type": "application/pdf", "url": "/6945/1/richards_joseph_l_2012_thesis.pdf", "version": "v14.0.0" }, "type": "thesis", "title": "The Radio Variability of Gamma-Ray Blazars", "author": [ { "family_name": "Richards", "given_name": "Joseph Lee", "clpid": "Richards-Joseph-Lee" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" }, { "family_name": "Harrison", "given_name": "Fiona A.", "orcid": "0000-0003-2992-8024", "clpid": "Harrison-F-A" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Since late 2007, we have regularly monitored over 1100 systematically selected blazars at 15 GHz using the Owens Valley Radio Observatory 40 m radio telescope. The number of sources in the program has grown to nearly 1600, including all the active galactic nuclei associated with Fermi Large Area Telescope (LAT) gamma-ray point source detections north of our declination limit of -20\u00b0. Here, we describe the first 42 months of this program, including the design and implementation of an automated data reduction pipeline and a MySQL database system for storing the reduced data and intermediate data products. Using the \"intrinsic modulation index,\" a maximum-likelihood method, we estimate the variability amplitudes for 1413 sources from their radio light curves and compare the properties of physically defined subpopulations of the sample. We find that, among our preselected sample, gamma-ray-loud blazars detected by the LAT are significantly more variable at 15 GHz, attributable to a difference in variability between the gamma-ray-loud and gamma-ray-quiet flat spectrum radio quasars. The BL Lacertae objects in the samples do not show this division in variability amplitudes. In the first two years of our program, a 3\u03c3-significant difference between variability amplitudes for sources at redshift z \u2265 1 and for sources at z < 1 was found. This difference is found no longer to be significant in the full 42-month data set, particularly after we apply an analysis method to account for the effect of cosmological time dilation. ", "doi": "10.7907/N69P-KG16", "publication_date": "2012", "thesis_type": "phd", "thesis_year": "2012" }, { "id": "thesis:10708", "collection": "thesis", "collection_id": "10708", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02132018-113613816", "primary_object_url": { "basename": "Karkare_KS_2011.pdf", "content": "final", "filesize": 8362634, "license": "other", "mime_type": "application/pdf", "url": "/10708/1/Karkare_KS_2011.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "A Ku-Band Polarimeter for the Owens Valley Radio Observatory 40-Meter Telescope", "author": [ { "family_name": "Karkare", "given_name": "Kirit Sukrit", "clpid": "Karkare-Kirit-Sukrit" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "None", "given_name": "None" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Blazars are active galactic nuclei - small, extremely luminous objects at the center of galaxies powered by material accreting around a supermassive black hole - which emit relativistic jets of\r\nhighly energetic plasma along our line of sight. There is no accepted model for jet composition, acceleration, and confinement; observations at different wavelengths will help us understand these\r\nemission mechanisms. Since 2007, the 40-Meter Telescope at the Owens Valley Radio Observatory has been monitoring over 1100 blazars every two days. The variability in radio light curves is\r\nlikely to be correlated with gamma-rays, which we are observing with the Fermi Gamma-Ray Space Telescope.
\r\n\r\nA new Ku-band receiver for the 40-Meter Telescope is in development. It will offer increased sensitivity, MHz spectral resolution from 12-18 GHz, and calculation of Stokes I, Q, and U parameters.\r\nIn this thesis, I present the design, assembly, and testing of various components in the receiver chain. I evaluate the suitability of a commercial radio frequency over optical link for use in the receiver,\r\ndescribe the fabrication and verification of bandpass filters and sideband separating modules, and present the design and testing of a digital back end spectrometer which uses field-programmable\r\ngate array devices.
\r\n\r\nWhen complete in late 2011 , the new receiver will allow the continuation of the blazar monitoring program with the addition of spectral and polarization information, which will be invaluable in\r\nunderstanding blazar jet emission.
", "doi": "10.7907/AX7Y-QF79", "publication_date": "2011", "thesis_type": "senior_major", "thesis_year": "2011" }, { "id": "thesis:1771", "collection": "thesis", "collection_id": "1771", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05132004-184937", "primary_object_url": { "basename": "psu_thesis.pdf", "content": "final", "filesize": 4115387, "license": "other", "mime_type": "application/pdf", "url": "/1771/1/psu_thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "H\u2080 from Cosmic Background Imager Observations of the Sunyaev-Zel\u2019dovich Effect in Nearby Clusters.", "author": [ { "family_name": "Udomprasert", "given_name": "Patricia Simcoe", "clpid": "Udomprasert-Patricia-Simcoe" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Lange", "given_name": "Andrew E.", "clpid": "Lange-A-E" }, { "family_name": "Blain", "given_name": "Andrew W.", "clpid": "Blain-A-W" }, { "family_name": "Djorgovski", "given_name": "George", "orcid": "0000-0002-0603-3087", "clpid": "Djorgovski-G" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We present H\u2080 results from Cosmic Background Imager (CBI) observations of the Sunyaev-Zeldovich Effect (SZE) in 7 galaxy clusters, A85, A399, A401, A478, A754, A1651, and A2597. These observations are part of a program to study a complete, volume-limited sample of low-redshift (z < 0.1), X-ray selected clusters. Our focus on nearby objects allows us to study a well-defined, orientation unbiased sample, minimizing systematic errors due to cluster asphericity. We use density models derived from ROSAT imaging data and temperature measurements from ASCA and BeppoSAX spectral observations. We quantify in detail sources of error in our derivation of H\u2080, including calibration of the CBI data, density and temperature models from the X-ray data, Cosmic Microwave Background (CMB) primary anisotropy fluctuations, and residuals from radio point source subtraction. From these 7 clusters we obtain a result of Ho = 67+30-18(ran)+15-6(sys) km/s-1 Mpc-1 for an unweighted sample average. The respective quoted errors are random and systematic uncertainties at 68% confidence. The dominant source of error is confusion from intrinsic anisotropy fluctuations. We present results from simulations of an eigenmode weighting analysis that reduce the uncertainties due to CMB in h-1/2 by ~30%.", "doi": "10.7907/VR2Z-MP09", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:2191", "collection": "thesis", "collection_id": "2191", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05282004-140350", "primary_object_url": { "basename": "main.pdf", "content": "final", "filesize": 2998326, "license": "other", "mime_type": "application/pdf", "url": "/2191/1/main.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Data Analysis of and Results from Observations of the Cosmic Microwave Background with the Cosmic Background Imager", "author": [ { "family_name": "Sievers", "given_name": "Jonathan LeRoy", "orcid": "0000-0001-6903-5074", "clpid": "Sievers-Jonathan-LeRoy" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Steidel", "given_name": "Charles C.", "orcid": "0000-0002-4834-7260", "clpid": "Steidel-C-C" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Kamionkowski", "given_name": "Marc P.", "orcid": "0000-0001-7018-2055", "clpid": "Kamionkowski-M-P" }, { "family_name": "Pearson", "given_name": "Timothy J.", "orcid": "0000-0001-5213-6231", "clpid": "Pearson-T-J" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We present results from observations of the Cosmic Microwave Background (CMB) with the Cosmic Background Imager (CBI), a sensitive 13-element interferometer located high in the Chilean Andes. We also discuss methods of analyzing the data from the CBI, including an improved way of measuring the true power spectrum using maximum likelihood estimation. This improved method leads to a saving of a factor of two in memory usage, and an increase in speed of order the number of points in the spectrum. The initial results are discussed, in which the fall-off in power at ell > 1000 (the \"damping tail\") was first observed. We also present the results from the first year of observations with the CBI, and discuss cosmological intepretations both alone and in concert with the results from other experiments. These provide tight constraints on cosmological parameters, including a Hubble constant of 69 +/- 4 km/s/Mpc, an age of the universe of 13.7 +/- 0.2 billion years, and a denisty of dark energy of 0.70 +/- 0.05 of the critical density of the universe. Finally, we discuss an alternate method of data compression, with great flexibility in what information is kept, while being computationally tractable. We then apply this method to the CBI data to constrain the potential emission from foreground contaminants contributing to the observed CMB radiation. We find that the data is consistent with zero foreground, with a maximum allowed foreground contribution between about 8% and 12% of the total signal (at an ell of 600 and frequency of 30 GHz), depending on the spectral index of foreground emission.\r\n", "doi": "10.7907/8706-VY52", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:2230", "collection": "thesis", "collection_id": "2230", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05292003-131234", "primary_object_url": { "basename": "jkc_thesis.pdf", "content": "final", "filesize": 6078828, "license": "other", "mime_type": "application/pdf", "url": "/2230/1/jkc_thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "A Limit on the Polarization of the Cosmic Microwave Background Radiation", "author": [ { "family_name": "Cartwright", "given_name": "John Kenneth", "clpid": "Cartwright-John-Kenneth" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Lange", "given_name": "Andrew E.", "clpid": "Lange-A-E" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Zmuidzinas", "given_name": "Jonas", "orcid": "0000-0002-3330-5439", "clpid": "Zmuidzinas-J" }, { "family_name": "Padin", "given_name": "Stephen", "orcid": "0009-0001-9993-4393", "clpid": "Padin-Stephen" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "We describe polarization observations of the CMBR with the Cosmic Background Imager, a 13-element interferometer which operates in the 26-36 GHz band and is located on the Llano de Chajnantor in northern Chile. The array consists of 90 cm Cassegrain antennas mounted on a steerable platform which can be rotated about the optical axis to facilitate polarization observations. The CBI employs single-mode circularly polarized receivers and it samples multipoles from \u2113 ~ 400 to \u2113 ~ 4250. The instrumental polarization of the CBI was calibrated with 3C279, a bright polarized point source which was monitored with the VLA. Observations of two deep fields during the 2000 season yielded three limits (95% c.l.) for C\u2113EE under the assumption that C\u2113BB = 0: 7.0 \u00b5K (\u2113 = 603); 12.8 \u00b5K (\u2113 = 1144); and 25.1 \u00b5K (\u2113 = 2048). The low-\u2113 limit approaches the levels of fluctuations predicted by standard models.
\r\n\r\nThis thesis also entailed the design and implementation of several major components of the CBI signal chain including the downconverter, the noise calibration system, and the low noise HEMT amplifiers. We discuss the design and performance of these critical systems.
", "doi": "10.7907/D3CT-YV96", "publication_date": "2003", "thesis_type": "phd", "thesis_year": "2003" }, { "id": "thesis:1884", "collection": "thesis", "collection_id": "1884", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05202002-104244", "primary_object_url": { "basename": "0_Complete_Thesis.pdf", "content": "final", "filesize": 12416662, "license": "other", "mime_type": "application/pdf", "url": "/1884/1/0_Complete_Thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "1:1 Motif for DNA Recognition by \u03b2-Alanine Linked Polyamides", "author": [ { "family_name": "Urbach", "given_name": "Adam Robert", "orcid": "0000-0003-3426-4760", "clpid": "Urbach-Adam-Robert" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Dervan", "given_name": "Peter B.", "orcid": "0000-0001-8852-7306", "clpid": "Dervan-P-B" } ], "thesis_committee": [ { "family_name": "Grubbs", "given_name": "Robert H.", "orcid": "0000-0002-0057-7817", "clpid": "Grubbs-R-H" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Dervan", "given_name": "Peter B.", "orcid": "0000-0001-8852-7306", "clpid": "Dervan-P-B" }, { "family_name": "Roberts", "given_name": "Richard W.", "orcid": "0000-0002-8587-5097", "clpid": "Roberts-R-W" }, { "family_name": "Mayo", "given_name": "Stephen L.", "orcid": "0000-0002-9785-5018", "clpid": "Mayo-S-L" } ], "local_group": [ { "literal": "div_chem" } ], "abstract": "Polyamides composed of N-methylpyrrole (Py), N-methylimidazole (Im), and 3-hydroxypyrrole (Hp) amino acids linked by beta-alanine (beta) bind in the minor groove of DNA in 1:1 and 2:1 ligand:DNA complexes. Although the energetics and structure of the 2:1 motif have been explored extensively, there is remarkably less understood about 1:1 recognition beyond the initial studies on netropsin and distamycin. Laemmli and coworkers used beta-linked polyamides, which bind in a 1:1 motif, to effect phenotypic changes in Drosophila melanogaster. The thesis work described here investigates Laemmli's 1:1 motif in order to further understand and exploit this novel mode of DNA recognition.
\r\n\r\ny selectively replacing Py residues with beta it was found that the Im-beta-Im subunit is important for high-affinity binding in 1:1 and 2:1 modes. This study also demonstrates that a single ligand can target very different DNA sequences based on 1:1 or 2:1 binding. This ambiguity of sequence targeting based on stoichiometry was addressed. It was discovered that hairpin and 1:1 binding modes, which are dependent on ligand conformation, are controlled by changing the linker between polyamide subunits.
\r\n\r\nThe possibility of developing a 1:1 recognition code was explored by selectively mutating polyamide residues and DNA base pairs and comparing the association constants for the resulting complexes. It was found that Im residues tolerate all four Watson-Crick base pairs; Py and beta residues are specific for A?T and T?A base pairs; and Hp specifies a single base pair, A?T, in the sequence context 5'-AAAGAGAAGAG-3'. Attempts to improve upon this recognition code using novel heterocyclic amino acids, such as furan, thiophene, thiazole, and hydroxythiophene, are presented. The sequence-dependence of ligand orientation and the effect of ligand size on binding affinity were also explored.
\r\n\r\nThe NMR structure of a 1:1 polyamide:DNA complex was determined. It reveals B-form DNA with a narrow minor groove and large negative propeller twist, which are shown to be stabilized by bifurcated hydrogen bonds between polyamide NH groups and purine N3 and pyrimidine O2 atoms. The first direct evidence is provided for hydrogen bond formation between Im-N3 and guanine NH2 in the 1:1 motif, thus confirming the original lexitropsin model.
", "doi": "10.7907/V6FD-YQ78", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:6796", "collection": "thesis", "collection_id": "6796", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:01302012-162107660", "primary_object_url": { "basename": "Lithwick_y_2002.pdf", "content": "final", "filesize": 28809074, "license": "other", "mime_type": "application/pdf", "url": "/6796/1/Lithwick_y_2002.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Topics in MHD Turbulence", "author": [ { "family_name": "Lithwick", "given_name": "Yoram", "orcid": "0000-0003-4450-0528", "clpid": "Lithwick-Yoram" } ], "thesis_advisor": [ { "family_name": "Goldreich", "given_name": "Peter Martin", "clpid": "Goldreich-P-M" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Goldreich", "given_name": "Peter Martin", "clpid": "Goldreich-P-M" }, { "family_name": "Blandford", "given_name": "Roger D.", "clpid": "Blandford-R-D" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Scoville", "given_name": "Nicholas Zabriskie", "orcid": "0000-0002-0438-3323", "clpid": "Scoville-N-Z" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "I consider two topics in MHD turbulence. First, I work out the theory of compressible MHD turbulence, including kinetic effects. I use this theory to understand features of interstellar scintillation that have hitherto been unexplained. Second, I work out the theory of imbalanced weak MHD turbulence.", "doi": "10.7907/FP3Q-EZ29", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:6796", "collection": "thesis", "collection_id": "6796", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:01302012-162107660", "primary_object_url": { "basename": "Lithwick_y_2002.pdf", "content": "final", "filesize": 28809074, "license": "other", "mime_type": "application/pdf", "url": "/6796/1/Lithwick_y_2002.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Topics in MHD Turbulence", "author": [ { "family_name": "Lithwick", "given_name": "Yoram", "orcid": "0000-0003-4450-0528", "clpid": "Lithwick-Yoram" } ], "thesis_advisor": [ { "family_name": "Goldreich", "given_name": "Peter Martin", "clpid": "Goldreich-P-M" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Goldreich", "given_name": "Peter Martin", "clpid": "Goldreich-P-M" }, { "family_name": "Blandford", "given_name": "Roger D.", "clpid": "Blandford-R-D" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" }, { "family_name": "Scoville", "given_name": "Nicholas Zabriskie", "orcid": "0000-0002-0438-3323", "clpid": "Scoville-N-Z" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "I consider two topics in MHD turbulence. First, I work out the theory of compressible MHD turbulence, including kinetic effects. I use this theory to understand features of interstellar scintillation that have hitherto been unexplained. Second, I work out the theory of imbalanced weak MHD turbulence.", "doi": "10.7907/FP3Q-EZ29", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:6982", "collection": "thesis", "collection_id": "6982", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04262012-150437308", "primary_object_url": { "basename": "Wurtz_nr_2002.pdf", "content": "final", "filesize": 7990180, "license": "other", "mime_type": "application/pdf", "url": "/6982/1/Wurtz_nr_2002.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Sequence Specific Alkylation of DNA by Polyamide-Chlorambucil Conjugates", "author": [ { "family_name": "Wurtz", "given_name": "Nicholas Roland", "orcid": "0000-0003-2574-9440", "clpid": "Wurtz-Nicholas-Roland" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Myers", "given_name": "Andrew G.", "orcid": "0000-0001-9602-6915", "clpid": "Myers-A-G" } ], "thesis_committee": [ { "family_name": "Grubbs", "given_name": "Robert H.", "orcid": "0000-0002-0057-7817", "clpid": "Grubbs-R-H" }, { "family_name": "Dervan", "given_name": "Peter B.", "orcid": "0000-0001-8852-7306", "clpid": "Dervan-P-B" }, { "family_name": "MacMillan", "given_name": "David W. C.", "orcid": "0000-0003-3352-4532", "clpid": "MacMillan-D-W-C" }, { "family_name": "Mayo", "given_name": "Stephen L.", "orcid": "0000-0002-9785-5018", "clpid": "Mayo-S-L" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Myers", "given_name": "Andrew G.", "orcid": "0000-0001-9602-6915", "clpid": "Myers-A-G" } ], "local_group": [ { "literal": "div_chem" } ], "abstract": "Small molecules that bind selectively to a DNA sequence in the human genome are potentially useful tools for molecular biology and human medicine. Polyamides containing N-methylimidazole (Im) and N-methylpyrrole (Py) are small molecules that bind DNA according to a set of \"pairing rules\" with affinities and specificities similar to many naturally occurring DNA binding proteins. Two alternate routes of synthesis of polyamides are presented that allowed improved synthesis of commonly used motifs as well as access to polyamides with truncated tails which increase the number of DNA sequences targetable by polyamides with high affinity. Py-Im polyamides may offer a general approach to chemical regulation of gene expression provided inhibition of DNA binding for a variety of transcription factor families can be achieved. Two successful strategies are shown for the inhibition of DNA binding by two such proteins, GCN4 and NF-\u03baB. An alternate method of gene regulation would be inhibition of transcription during the elongation phase by site-specific alkylation in the coding region of genes. A new class of compounds is created by the attachment of a bis (dichloroethylamino)-benzene nonspecific DNA alkylator to polyamides, which alkylate DNA with high yield and specificity. The biological activity and cell permeability of one of these compounds in several systems is studied.
", "doi": "10.7907/59jz-2e47", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:6996", "collection": "thesis", "collection_id": "6996", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05012012-101216772", "primary_object_url": { "basename": "Wang_ccc_2002.pdf", "content": "final", "filesize": 5350283, "license": "other", "mime_type": "application/pdf", "url": "/6996/1/Wang_ccc_2002.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Sequence Specific Trapping of Topoisomerase I by Camptothecin Polyamide Conjugates", "author": [ { "family_name": "Wang", "given_name": "Clay Chia Chun", "clpid": "Wang-Clay-Chia-Chun" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Dervan", "given_name": "Peter B.", "orcid": "0000-0001-8852-7306", "clpid": "Dervan-P-B" } ], "thesis_committee": [ { "family_name": "Rees", "given_name": "Douglas C.", "orcid": "0000-0003-4073-1185", "clpid": "Rees-D-C" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Dervan", "given_name": "Peter B.", "orcid": "0000-0001-8852-7306", "clpid": "Dervan-P-B" }, { "family_name": "Stoltz", "given_name": "Brian M.", "orcid": "0000-0001-9837-1528", "clpid": "Stoltz-B-M" }, { "family_name": "Roberts", "given_name": "Richard W.", "clpid": "Roberts-R-W" } ], "local_group": [ { "literal": "div_chem" } ], "abstract": "Polyamides containing N-methylpyrrole (Py)N-methylimidazole (Im) and 3-hydroxy-1-methylpyrrole (Hp) are cell permeable small molecules that bind as antiparallel pairs in the minor groove of DNA according to a set of \"pairing rules\" with affinities and specificities for predetermined sequences comparable to DNA-binding proteins. Several of these ring pairings have only been demonstrated when placed internal in a hairpin and not for the terminal position in hairpin polyamides. Several series of eight ring hairpin polyamides with modification at the N-terminal position were synthesized and characterized. We observed that at the terminal position (i) the Py/Py pair functions similar to when placed internally preferring A\u2022T and T\u2022A base pairs over O\u2022C and C\u2022O, (ii) the Hp/Py pair could not distinguish between T\u2022A over A-T possibly due to rotation of the terminal Hp to form an intramolecular hydrogen bond between the 3-hydroxyl hydrogen and the carboxamide oxygen which would orient the key hydroxyl recognition element away from the minor groove. A new aromatic pair, 2-hydroxy-6-methoxybenzamidell-methylpyrrole was designed and shown to distinguish T\u2022A from A\u2022T base pairs and both from O\u2022C/C\u2022O and (iii) the Py/Im pair in the classic eight ring hairpin motif showed no preference for C\u2022O base pair possibly due to the mispositioning of the Im residue located at the C-terminal end of the four ring polyamide subunit. Targeting of C\u2022O was accomplished by replacing a pyrrole with a flexible \u03b2-alanine and setting the imidazole back in register.
\r\n\r\nPyrrole-imidazole polyamides that target DNA sequences in the promoter have been shown to inhibit transcription of specific genes in cell culture. When bound to coding region of genes, polyamides do not appear to inhibit gene expression. A possible solution is to design molecule capable of modifying DNA when bound to the coding region. A series of polyamide-camptothecin conjugates were designed to trap the enzyme Topoisomerase I and induce cleavage at predetermined DNA sites. Cleavage yields were shown to be dependent on linker length between the DNA binding polyamide\r\nand the Topo I trapping camptothecin unit with the camptothecin unit with the longest linker showing greatest cleavage yield of over 90%.
\r\n", "doi": "10.7907/sphn-ma74", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:1680", "collection": "thesis", "collection_id": "1680", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05082006-143046", "primary_object_url": { "basename": "Cornu_c_2002.pdf", "content": "final", "filesize": 5807149, "license": "other", "mime_type": "application/pdf", "url": "/1680/1/Cornu_c_2002.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Photocatalysis Under Periodic Illumination", "author": [ { "family_name": "Cornu", "given_name": "Catherine J. G.", "clpid": "Cornu-Catherine-J-G" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Hoffmann", "given_name": "Michael R.", "orcid": "0000-0001-6495-1946", "clpid": "Hoffmann-M-R" } ], "thesis_committee": [ { "family_name": "Hoffmann", "given_name": "Michael R.", "orcid": "0000-0001-6495-1946", "clpid": "Hoffmann-M-R" }, { "family_name": "Blake", "given_name": "Geoffrey A.", "orcid": "0000-0003-0787-1610", "clpid": "Blake-G-A" }, { "family_name": "Hering", "given_name": "Janet G.", "clpid": "Hering-J-G" }, { "family_name": "Lewis", "given_name": "Nathan Saul", "orcid": "0000-0001-5245-0538", "clpid": "Lewis-N-S" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In the first part of this work, the use of periodic illumination is investigated as a means to improve the quantum yield of aqueous phase photocatalysis. We find that quantum yield enhancements are obtained under periodic illumination compared to those under continuous illumination with the same maximum photon absorption rate. This result is in agreement with previous literature reports. However, no enhancements are obtained when compared to those under continuous illumination with the same average photon absorption rate. Ways in which the use of periodic illumination in remediation systems might nevertheless be more cost-effective than continuous operation are discussed. In the second part of this work, periodic illumination is applied as a tool to investigate the kinetic behavior of the intermediates involved in photocatalysis. Two transitions are observed in the quantum yield as a function of the active light period, corresponding to separate lifetimes of two intermediates. These lifetimes are found to be relatively insensitive to the physical properties of the TiO2 photocatalyst particles, the compound being photocatalytically oxidized, or the oxygen concentration. However, a strong correlation with the pH of the solution is observed. For example, one intermediate's lifetime increases exponentially with pH, while the other one's decreases exponentially. Principles from electrochemistry, namely Nernst's law and the Butler-Volmer equation, allow us to conclude that the intermediate with a decreasing lifetime with pH is a reducing species, while the other one is an oxidizing species. The intermediates' lifetimes are equal at a pH ~ 8, concurrent with a minimum in quantum yield. Below pH 8 the reducing species has a longer lifetime, indicating that interfacial electron transfer to oxygen is the slowest step under these conditions.
\r\n\r\nThe observed lifetimes are compatible with those previously measured for superoxide radicals (reducing species), and hydroxyl radicals, surface trapped holes, or surface bound hydroxyl radicals (oxidizing species).
", "doi": "10.7907/ZDAH-V967", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:1512", "collection": "thesis", "collection_id": "1512", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-04262005-152703", "primary_object_url": { "basename": "Kee_s_2002.pdf", "content": "final", "filesize": 36463553, "license": "other", "mime_type": "application/pdf", "url": "/1512/1/Kee_s_2002.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "The Class E/F Family of Harmonic-Tuned Switching Power Amplifiers", "author": [ { "family_name": "Kee", "given_name": "Scott David", "clpid": "Kee-Scott-David" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "McEliece", "given_name": "Robert J.", "clpid": "McEliece-R-J" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nA new family of harmonic-tuned switching amplifiers is introduced having the beneficial features of the class-E tuning while allowing improved performance to be achieved through additional harmonic tuning. This E/F family may be tuned to achieve the ZVS/ZdVS switching features characteristic of the class-E amplifier and, like the class-E tuning, accounts and compensates for the effect of the switch parallel capacitance. By tuning one or more overtones to the [...] tuning, however, the switching waveforms may be improved, lowering the peak voltage and reducing the RMS current. Additionally, the tolerance to large switch parallel capacitance is generally improved so that a larger switching device may be used, allowing reduction of the on-resistance. Due to these factors, the efficiency of E/F amplifiers is expected to exceed that of class E.\r\n\r\nTo demonstrate these advantages, methods of estimating the optimal efficiency of switching amplifiers using waveform properties are given. A general solution technique is then presented which allows the calculation of the ZVS tuning requirements and the resulting switching waveforms for an arbitrary harmonic tuning. Using these two tools, switching waveforms and resulting efficiency estimates are calculated for E/F amplifier tunings, which are then compared to class E.\r\n\r\nFinally, potential application areas of the E/F technique are explored, and measured results of several first-generation E/F amplifiers are presented. Aside from efficiency benefits, E/F amplifiers also may achieve load-invariance, dual- and multi-band operation, high volumetric power densities, and efficient integrated circuit implementation using the Aoki distributed active transformer power combining structure.\r\n", "doi": "10.7907/MD86-FX51", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:3735", "collection": "thesis", "collection_id": "3735", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09232008-094506", "primary_object_url": { "basename": "Fassnacht_cd_1999.pdf", "content": "final", "filesize": 8198528, "license": "other", "mime_type": "application/pdf", "url": "/3735/1/Fassnacht_cd_1999.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Determining the distance scale with CLASS: studies of two new gravitational lenses and a measurement of the Hubble constant", "author": [ { "family_name": "Fassnacht", "given_name": "Christopher D.", "clpid": "Fassnacht-Christopher-D" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\n\r\nGravitational lenses have the potential to be excellent tools for investigating the Universe. This thesis describes the Cosmic Lens All-Sky Survey (CLASS), a program to find new gravitational lenses, and presents data on two newly-discovered lenses, 1608+656 and 2045+265. One of the major goals of CLASS is to find \"golden lenses,\" which can be used to measure the Hubble Constant H[...]. A measurement of H[...] requires the redshifts of the lensing object and the background source, a well-constrained model of the gravitational potential of the lensing object, and a measurement of time delays between the images of the background source.\r\n\r\nThe 1608+656 system contains four images of the background source, which is the unresolved core of a classical radio double source. The lensing galaxy is at a redshift of [...] = 0.630, while the background source is at a redshift of [...] = 1.394. Interestingly, the spectrum of the background object indicates that it is an \"E + A\" galaxy. Ground-based optical and infrared images clearly show the lensing galaxy at the location predicted by the lens models. Images taken with instruments on the Hubble Space Telescope further resolve the lensing galaxy into two distinct objects, which may be a merging pair of galaxies.\r\n\r\nRadio maps of the 2045+265 system also show four images of the background source. In addition, a fifth component appears in the maps. The radio spectrum of the fifth component is significantly different from the spectra of the other four components, and its location matches that of the lensing galaxy to within the positional errors. Therefore, it appears that the fifth component is the flat-spectrum core of the lensing galaxy. The redshift of the lensing galaxy is [...] = 0.8673. The spectrum of the background source shows one broad emission line, which appears to be Mg II at a redshift of [...] = 1.28. However, this redshift implies that the lensing galaxy is unusually massive and would have a rotation velocity two to three times what is observed in nearby galaxies of the same type. There is either a significant contribution by dark (or underluminous) matter associated with the lensing object or the source redshift is incorrect. More sensitive spectroscopy is needed to resolve this issue.\r\n\r\nPreliminary observations of the 1608+656 system showed that the component flux densities varied by ~15% on time scales of months. For this reason, I conducted a dedicated monitoring program with the Very Large Array (VLA) from October 1996 to May 1997. The observations took place, on average, every four days. The calibrated light curves for components A, B, C, and D show variations in flux density at the 3-5% level. Although the fractional variations are small, the time delays between the curves can be measured. The final values are [...], and [...], where the 95% confidence levels have been obtained from Monte Carlo simulations. The model of the mass distribution of the lens correctly reproduces the image positions, flux ratios, and time delay ratios. The combination of the measured time delays with the lens model yields the first determination of H[...] from a CLASS lens: H[...] = [...] (statistical) \u00b1 15(systematic) km sec[superscript -1] Mpc[superscript -1].", "doi": "10.7907/pe8p-yc41", "publication_date": "1999", "thesis_type": "phd", "thesis_year": "1999" }, { "id": "thesis:3142", "collection": "thesis", "collection_id": "3142", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-08162006-081019", "primary_object_url": { "basename": "Leitch_em_1998.pdf", "content": "final", "filesize": 9750136, "license": "other", "mime_type": "application/pdf", "url": "/3142/1/Leitch_em_1998.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "A measurement of anisotropy in the microwave background on 7'-22' scales", "author": [ { "family_name": "Leitch", "given_name": "Erik M.", "clpid": "Leitch-Erik-M" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nA measurement of the anisotropy of the cosmic microwave background radiation (CMBR) at 7'-22' scales is described. Observations of 36 blank fields near the North Celestial Pole (NCP) were made at 31.7 and 14.5 GHz, using two High Electron Mobility Transistor (HEMT) amplified radiometers. These observations were conducted at the Owens Valley Radio Observatory from 1993-1996.\r\n\r\nWe detect a significant signal, with temperature spectral index consistent with emission from a combination of a steep-spectrum foreground ([beta] < -2) and CMBR ([...]). Multi-epoch VLA observations at 8 and 15 GHz allow removal of any discrete source contamination at 14.5 and 31.7 GHz. On the basis of low-frequency maps of the NCP, we can rule out emission with [beta] < -2.2. Although the foreground signal dominates at 14.5 GHz, the extracted CMBR component contributes nearly 90% of the variance at 31.7 GHz, yielding an rms fluctuation amplitude of [...], including calibration uncertainty and sample variance. In terms of the angular power spectrum [...] averaged over a range of multipoles [...], we have [...].\r\n\r\nThe extracted foreground component is found to correlate significantly with IRAS 100 [mu] m dust emission. Lack of H [alpha] emission near the NCP suggests that the foreground is either high-temperature thermal bremsstrahlung [...], flat spectrum synchrotron, or an exotic component of dust emission.\r\n", "doi": "10.7907/DRVA-T966", "publication_date": "1998", "thesis_type": "phd", "thesis_year": "1998" }, { "id": "thesis:4272", "collection": "thesis", "collection_id": "4272", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-10262007-132906", "primary_object_url": { "basename": "Xu_w_1995.pdf", "content": "final", "filesize": 12298460, "license": "other", "mime_type": "application/pdf", "url": "/4272/1/Xu_w_1995.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "The first Caltech-Jodrell Bank VLBI survey", "author": [ { "family_name": "Xu", "given_name": "Wenge", "clpid": "Xu-Wenge" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nThis thesis presents the author's major contributions to the first Caltech-Jodrell Bank VLBI survey (CJ1). It demonstrates convincingly that the VLBI snapshot technique is a reliable and highly efficient method of making images of large samples of objects.\r\n\r\nThe CJ1 sample consists of 135 objects with 1.3 Jy > [...] GHz [...] 0.7 Jy, [...](1950) [...] 35\u00b0 and [...] > 10\u00b0. The combination of the CJ1 sample with the Pearson-Readhead sample provides a complete, flux density limited sample of 200 objects with [...] GHZ [...] 0.7 Jy, [...](1950) [...] 35\u00b0 and [...] > 10\u00b0 for which all of the objects accessible to Mark II VLBI have been mapped at both 5 GHz and 1.6 GHz. In this thesis we present the 5 GHz VLBI observations from the CJ1 survey and follow-up observations of 8 compact symmetric objects (CSO) or CSO candidates at 8.4 GHz. In addition, we present 5 GHz MERLIN observations of 20 objects and 1.4 GHz VLA observations of 92 objects in the CJ1+PR sample. The VLA maps, together with L band (1.3-1.7 GHz) maps available in the literature, provide a complete set of VLA maps for the CJ1+PR sample. Furthermore, we present new redshifts, optical counterparts and optical polarimetry measurements of the objects in the CJ1 sample.\r\n\r\nBased on morphological attributes on scales < 5 kpc and [...] 5 kpc, we identify six physically distinct classes in the CJ1+PR sample, one of which is the CSO class. Identification of CSO's may have a profound impact on our understanding of AGN. Detailed study of one archetypal CSO, 2352+495, has demonstrated that the CSO's are likely a class of short-lived powerful galaxies.\r\n\r\nWe have confirmed the bimodal distribution of the misalignment angle and identified that the peak near 90\u00b0 is contributed by a group of objects with high optical polarization, high fractional core flux, high radio variability and flat radio spectrum. All of these are symptoms of relativistic beaming.\r\n\r\nThe mean angular sizes of the CJ1+PR objects show only slight dependence on redshift, contrary to the finding by Kellermann. However, our results show that the angular size distributions of objects with z < 0.1 and those with z > 0.1 are significantly different. This may indicate an evolutionary effect.\r\n", "doi": "10.7907/k8f8-gn20", "publication_date": "1995", "thesis_type": "phd", "thesis_year": "1995" }, { "id": "thesis:3446", "collection": "thesis", "collection_id": "3446", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09102008-151722", "primary_object_url": { "basename": "Herbig_th_1994.pdf", "content": "final", "filesize": 6849441, "license": "other", "mime_type": "application/pdf", "url": "/3446/1/Herbig_th_1994.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "A measurement of the Sunyaev-Zeldovich effect in the coma cluster of galaxies", "author": [ { "family_name": "Herbig", "given_name": "Thomas", "clpid": "Herbig-Thomas" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Unknown", "given_name": "Unknown" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "This thesis presents a measurement of the Sunyaev-Zeldovich effect in the Coma cluster of galaxies. The observed effect is \u0394T[subscript 0,obs] = -302.1\u00b148\u03bcK, and was measured at a frequency of 32GHz with the 5.5m telescope at the Owens Valley Radio Observatory. Interpreted in the context of existing X-ray models, I derive a peak central SZ effect of \u0394T[subscript 0,peak] = -495.3\u00b178.7\u00b5K. With this interpretation, I also calculate a value of H[subscript 0] = 74.2\u00b127.9kms[superscript -1]Mpc[superscript -1] for the Hubble constant. This is the first successful measurement of the SZ effect in a nearby cluster, an important advance because of the much better potential for its astronomical and cosmological interpretation.", "doi": "10.7907/3wd8-xa84", "publication_date": "1994", "thesis_type": "phd", "thesis_year": "1994" }, { "id": "thesis:3444", "collection": "thesis", "collection_id": "3444", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09102008-135630", "primary_object_url": { "basename": "Myers_st_1990.pdf", "content": "final", "filesize": 8686628, "license": "other", "mime_type": "application/pdf", "url": "/3444/1/Myers_st_1990.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "A Search for Anisotropy in the Cosmic Microwave Background on Angular Scales of 1 to 30 Arcminutes", "author": [ { "family_name": "Myers", "given_name": "Steven Theodore", "clpid": "Myers-Steven-Theodore" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Mould", "given_name": "Jeremy R.", "orcid": "0000-0003-3820-1740", "clpid": "Mould-J-R" }, { "family_name": "Sargent", "given_name": "Wallace L. W.", "clpid": "Sargent-W-L-W" }, { "family_name": "Phinney", "given_name": "E. Sterl", "orcid": "0000-0002-9656-4032", "clpid": "Phinney-E-S" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Observations at a frequency of 20 GHz from the Owens Valley Radio Observatory with the 40-meter diameter radiotelescope are used to place limits on the anisotropy of the cosmic microwave background radiation, believed to be a relic from the Big Bang. Two experiments, designated NCP and RING, were performed with the former consisting of deep measurements in 8 fields at the declination \u03b4 = 89\u00b0 and the latter a survey of 96 fields at declination \u03b4 = 88\u00b0 10'42\". Bayesian statistical analysis of the 8 NCP field observations place a 95% confidence upper limit of \u03b4T/T < 1.9 x 10-5 (in fractions of the microwave background temperature 2.735 K) and 4.2 x 10-5 for 99.87% confidence (3\u03c3) on the amplitude of fluctuations with a characteristic correlation length of 2'.6. The 96 fields of the RING experiment were observed in an interlocked ring-like geometry to enhance the sensitivity of the experiment to larger-scale anisotropies. Because of the larger area of sky covered, this data was more susceptible to contamination by discrete extragalactic radio sources and separate lower frequency observations were used to identify and correct for the contributions of these objects. The statistical analysis of the RING data results in the limits on the anisotropy of 2.5 < \u03b4T/T < 5.0 x 10-5 (95%) and 1.9 < \u03b4T/T < 6.1 x 10-5 (99.87%) for fluctuations with a correlation angle of 2'.6. Because of the high probability of residual discrete source contamination, these results are treated as upper limits on intrinsic background fluctuations. These experiments constrain the amplitude to be less than 3 x 10-4 for correlation angles between 0'.1 and 30' (95%). The implications for cosmology and theories of galaxy formation are discussed, and models without significant non-baryonic matter and/or non-standard recombination are excluded by the observations.\r\n", "doi": "10.7907/p4e7-rw11", "publication_date": "1990", "thesis_type": "phd", "thesis_year": "1990" }, { "id": "thesis:3434", "collection": "thesis", "collection_id": "3434", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09102008-091002", "primary_object_url": { "basename": "Hough_dh_1986.pdf", "content": "final", "filesize": 5668667, "license": "other", "mime_type": "application/pdf", "url": "/3434/1/Hough_dh_1986.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Parsec-Scale Structure in the Nuclei of Double-Lobed Radio Quasars", "author": [ { "family_name": "Hough", "given_name": "David Hans", "clpid": "Hough-David-Hans" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Cohen", "given_name": "Marshall H.", "clpid": "Cohen-M-H" }, { "family_name": "Blandford", "given_name": "Roger D.", "clpid": "Blandford-R-D" }, { "family_name": "Schmidt", "given_name": "Maarten", "clpid": "Schmidt-M" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "A complete sample of double-lobed quasars is defined, which is believed to be randomly oriented and which contains many objects with central components accessible to very-long-baseline interferometry (VLSI). The purpose of defining the sample in this way is to facilitate tests of physical models proposed to explain both the compact and extended structures in extragalactic radio sources. Statistical studies of the properties of these objects on the >~ kiloparsec scale are consistent with the assumption of random orientations and the simple relativistic beaming theory.
\r\n\r\nThe central components of six double-lobed quasars have been mapped at high resolution and high sensitivity with VLBI. Each object exhibits a double or extended structure on the the ~parsec scale. This structure can be interpreted as a \"core-jet,\" the same morphology found in the dominant cores of powerful flat-spectrum sources, thus indicating a relation between the two classes of compact radio source. The presumed VLBI jets are all fairly well aligned with >~kiloparsec-scale, one-sided jets. The fact that the VLBI and large-scale jets always lie on the same side of the compact core suggests the same cause for the asymmetric structure on both scales.
\r\n\r\nThe central components of 3C245 and 3C263 have been mapped at three epochs. We find superluminal expansion in 3C263 with an apparent velocity of ~1.5c, and argue that there is evidence that 3C245 will also be found to be superluminal. These results are consistent with the simple beaming theory. It is thus clear that we will be able to measure component motion in many of these objects, which will permit us to distinguish among alternative theories of parsec-scale structure and motion.
\r\n\r\nThe future study of these compact central components will benefit greatly from the increased resolution afforded by both higher frequency, ground-based VLBI and VLBI using a radio telescope in Earth orbit.
\r\n", "doi": "10.7907/8P47-SM58", "publication_date": "1986", "thesis_type": "phd", "thesis_year": "1986" }, { "id": "thesis:3409", "collection": "thesis", "collection_id": "3409", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09092008-093723", "primary_object_url": { "basename": "Simon_rs_1983.pdf", "content": "final", "filesize": 4341639, "license": "other", "mime_type": "application/pdf", "url": "/3409/1/Simon_rs_1983.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Nuclear Structure of Quasars at 329 Megahertz", "author": [ { "family_name": "Simon", "given_name": "Richard Stanley", "clpid": "Simon-Richard-Stanley" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Blandford", "given_name": "Roger D.", "clpid": "Blandford-R-D" }, { "family_name": "Cohen", "given_name": "Marshall H.", "clpid": "Cohen-M-H" }, { "family_name": "Schmidt", "given_name": "Maarten", "clpid": "Schmidt-M" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "In the four chapters in this thesis are presented studies of compact quasars using Very Long Baseline Interferometry at 329 MHz.
\r\n\r\nThe first chapter presents hybrid maps of two quasars, 3C147 and 3C286, made at 329 MHz from VLBI observations taken in 1975 with a three station interferometer. The observations presented in the first chapter were used to make the first detailed maps of compact radio structure at this frequency. Both objects consist of an unresolved core; an extended, asymmetric jet; and an even larger, completely resolved halo. For 3C147 it is possible to decompose the spectrum into individual component spectra; at 329 MHz the core of 3C147 is found to be strongly self-absorbed. For both sources the spectral index decreases monotonically from core to jet to halo.
\r\n\r\nThe second chapter presents further observations of quasars at 329 MHz. These observations were taken with a seven-station interferometer and were used to produce high dynamic range maps of the quasars 3C48, 3C147, 3C309.1, 3C380, and 3C454.3. These maps, made with the most extensive low-frequency VLBI observations to date, are the first reliable, high dynamic range maps at this frequency, and reveal extremely complex source structure in four of these sources. All five of the objects are seen to have asymmetric structure that can be interpreted in the \"core-jet\" picture of compact extragalactic radio sources. The jets observed in these objects are not straight, but bent; three of these quasars have bends in their structure greater than 90\u00b0 on scales of 1 - 10 kpc.
\r\n\r\nChapter three deals with the analysis of the two maps of 3C147 presented in chapters 1 and 2. Comparison of those maps reveals that the core of 3C147 is a low-frequency variable radio source which has brightened by a factor of two in six years. In combination with X-ray observations this is used to demonstrate that bulk relativistic motion is taking place within the core and leads to the prediction that 3C147 is a member of the class of \"superluminal\" radio sources. It is also found that the inclination to the line of sight of the underlying bulk relativistic motion is less than 10\u00b0.
\r\n\r\nA self-consistent picture of 3C147 as a low-frequency variable is thus developed which is consistent with the available observations, yet does not require an extreme value of the total energy: the total energy of the core of 3C147 is found to be ~1054 ergs. Together with NRAO 140 there are now two extragalactic low-frequency variable radio sources in which bulk relativistic motion has been demonstrated. Thus it may well be that bulk relativistic motion is responsible for the required time-scales in most, if not all, low-frequency variables.
\r\n\r\nIn chapter four, the observations presented in chapter two of 3C48, 3C147, 3C309.1, 3C380 and 3C4S4.3 are analyzed using standard synchrotron emission theory in order to discover the physical conditions occurring in these objects. For 3C48, the suggestion in chapter 2 of this source as a \"core-jet\" source is seen to be reasonable with fields energy density and pressure all decreasing with increasing distance from the supposed core. For 3C48, the suggestion in chapter 2 of this source as a \"core-jet\" source is seen to be reasonable, with fields, energy density, and pressure all decreasing with increasing distance from the supposed core. The pressure in the jet in 3C48 is extremely large, implying that the jet cannot be confined by external gas pressure, unless the surrounding medium has extreme values of the temperature and density. In the case of 3C147 (which was analyzed extensively in chapter 3), the halfwidth of the observed jet implies that collimation of the jet is occurring; the jet in 3C147 is definitely not a \"free\" jet. For 3C309.1, the 329 MHz observations give an upper limit to the turnover frequency for synchrotron self-absorption significantly lower than that available up to now; this limit, in combination with Einstein X-ray observations of 3C309.1, implies that bulk relativistic motion is occurring within the core of 3C309.1. Thus, the core of 3C309.1 may be very similar to the core of 3C147, and is a candidate for being both a superluminal source and a low-frequency variable. For 3C380 and 3C454.3, the limited spectral information available allows broad limits to be put on their properties.
\r\n", "doi": "10.7907/zyfw-8c64", "publication_date": "1983", "thesis_type": "phd", "thesis_year": "1983" }, { "id": "thesis:3317", "collection": "thesis", "collection_id": "3317", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09022008-153247", "type": "thesis", "title": "Studies of Compact Extragalactic Radio Sources", "author": [ { "family_name": "Linfield", "given_name": "Roger Paul", "clpid": "Linfield-Roger-Paul" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Hall", "given_name": "Marshall", "clpid": "Hall-M" } ], "thesis_committee": [ { "family_name": "Blandford", "given_name": "Roger D.", "clpid": "Blandford-R-D" }, { "family_name": "Kellerman", "given_name": "Kenneth I.", "clpid": "Kellerman-Kenneth-I" }, { "family_name": "Young", "given_name": "Peter J.", "clpid": "Young-Peter-J" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "Owens Valley Radio Observatory (OVRO)" }, { "literal": "TAPIR" }, { "literal": "Astronomy Department" }, { "literal": "div_pma" } ], "abstract": "Three studies of compact, extragalactic radio sources are presented.
\r\n\r\nIn the first, VLBI maps are presented of the nuclear cores of four radio galaxies which have large symmetric radio lobes: 3C 111, 3C 390.3, Cyg A, and 0055+30. Each source contains a nuclear jet having a scale of 1 pc, but no counterjets are seen. The jets in 3C 111 and 0055+30 point directly at the outer radio lobes, but in 3C 390.3 and Cyg A the jets are pointed from 4 to 6 degrees away from the lobes.
\r\n\r\nThe implications of the maps and models of these sources are considered in the second study. It is concluded that in all four cases, the observed asymmetry reflects an intrinsic asymmetry on a msec scale. The minimum pressure in the four jets is calculated, and it is concluded that the jet in Cyg A is very unlikely to be confined by gas pressure.
\r\n\r\nIn the third study, an attempt is made to explain the structure of compact radio sources with a precession-like motion or a relativistic jet. It is found that the curvature of these sources can be readily explained in this way. In addition, the knots which are often revealed by VLBI observations arise naturally in such a model. The main problem with the model is that it cannot by itself explain the arcsecond structure of asymmetric radio sources.
", "doi": "10.7907/5cg5-0d24", "publication_date": "1981", "thesis_type": "phd", "thesis_year": "1981" } ]