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Pulsar Timing Sensitivity To Very-Low-Frequency Gravitational Waves, Fredrick A. Jenet, J. W. Armstrong, Massimo Tinto Apr 2011

Pulsar Timing Sensitivity To Very-Low-Frequency Gravitational Waves, Fredrick A. Jenet, J. W. Armstrong, Massimo Tinto

Physics & Astronomy Faculty Publications

We compute the sensitivity, constrained by instrumental, propagation, and other fundamental noises, of pulsar timing to very-low-frequency gravitational waves (GWs). Reaching predicted GW signal strengths will require suppression of time-of-arrival fluctuations caused by interstellar plasma turbulence and a reduction of white rms timing noise to ≲100  ns. Assuming negligible intrinsic pulsar rotational noise, perfect time transfer from time standard to observatory, and stable pulse profiles, the resulting single-pulsar signal-to-noise ratio=1 sensitivity is limited by terrestrial time standards at ℎrms∼2×10−16  [f/(1  cycle/year)]−1/2 for 𝑓<3×10−8  Hz, where f is the Fourier frequency and a bandwidth of 1 cycle/(10 years) is assumed. Since this sensitivity is comparable to predicted GW signal levels, a reliable detection will require substantial signal-to-noise ratio improvement via pulsar timing array.

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When Is Hyponormality For 2-Variable Weighted Shifts Invariant Under Powers?, Raul E. Curto, Jasang Yoon Apr 2011

When Is Hyponormality For 2-Variable Weighted Shifts Invariant Under Powers?, Raul E. Curto, Jasang Yoon

School of Mathematical & Statistical Sciences Faculty Publications

Abstract. For 2-variable weighted shifts W(α,β) ≡ (T1, T2) we study the invariance of (joint) khyponormality under the action (h, ℓ) 7→ W (h,ℓ) (α,β) := (T h 1 , T ℓ 2 ) (h, ℓ ≥ 1). We show that for every k ≥ 1 there exists W(α,β) such that W (h,ℓ) (α,β) is k-hyponormal (all h ≥ 2, ℓ ≥ 1) but W(α,β) is not k-hyponormal. On the positive side, for a class of 2-variable weighted shifts with tensor core we find a computable necessary condition for invariance. Next, we exhibit a large nontrivial class for which hyponormality …

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Los Arcos - Spring 2011, University Of Texas-Pan American Apr 2011

Los Arcos - Spring 2011, University Of Texas-Pan American

UTPA Archives - Los Arcos Magazine

No abstract provided.

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Utb/Tsc Commencement – Spring 2011, University Of Texas At Brownsville, Texas Southmost College Apr 2011

Utb/Tsc Commencement – Spring 2011, University Of Texas At Brownsville, Texas Southmost College

Brownsville Archives - Legacy Commencement Programs

No abstract provided.

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Utpa Commencement – Spring 2011, University Of Texas-Pan American Apr 2011

Utpa Commencement – Spring 2011, University Of Texas-Pan American

Edinburg Archives - Legacy Commencement Programs

No abstract provided.

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Fabrication Of Poly(Vinylidene Fluoride) (Pvdf) Nanofibers Containing Nickel Nanoparticles As Future Energy Server Materials, Faheem A. Sheikh, Travis Cantu, Javier Macossay-Torres, Hern Kim Apr 2011

Fabrication Of Poly(Vinylidene Fluoride) (Pvdf) Nanofibers Containing Nickel Nanoparticles As Future Energy Server Materials, Faheem A. Sheikh, Travis Cantu, Javier Macossay-Torres, Hern Kim

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

In the present study, we introduce Poly(vinylidene fluoride) (PVDF) nanofibers containing nickel (Ni) nanoparticles (NPs) as a result of an electrospinning. Typically, a colloidal solution consisting of PVDF/Ni NPs was prepared to produce nanofibers embedded with solid NPs by electrospinning process. The resultant nanostructures were studied by SEM analyses, which confirmed well oriented nanofibers and good dispersion of Ni NPs over them. The XRD results demonstrated well crystalline feature of PVDF and Ni in the obtained nanostructures. Physiochemical aspects of prepared nano-structures were characterized for TEM which confirmed nanofibers were welloriented and had good dispersion of Ni NPs. Furthermore, the …

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The Collegian (2011-03-28), Christine Cavazos Mar 2011

The Collegian (2011-03-28), Christine Cavazos

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 63, No. 24

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Constraining The Coalescence Rate Of Supermassive Black-Hole Binaries Using Pulsar Timing, Z. L. Wen, F. A. Jenet, D. Yardley, G. B. Hobbs, R. N. Manchester Mar 2011

Constraining The Coalescence Rate Of Supermassive Black-Hole Binaries Using Pulsar Timing, Z. L. Wen, F. A. Jenet, D. Yardley, G. B. Hobbs, R. N. Manchester

Physics & Astronomy Faculty Publications

Pulsar timing observations are used to place constraints on the rate of coalescence of supermassive black-hole (SMBH) binaries as a function of mass and redshift. In contrast to the indirect constraints obtained from other techniques, pulsar timing observations provide a direct constraint on the black-hole merger rate. This is possible since pulsar timing is sensitive to the gravitational waves (GWs) emitted by these sources in the final stages of their evolution. We find that upper bounds calculated from the recently published Parkes Pulsar Timing Array data are just above theoretical predictions for redshifts below 10. In the future, with improved …

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An Empirical Ubv Ri Jhk Color-Temperature Calibration For Stars, Guy Worthey, Hyun Chul Lee Mar 2011

An Empirical Ubv Ri Jhk Color-Temperature Calibration For Stars, Guy Worthey, Hyun Chul Lee

Physics & Astronomy Faculty Publications

A collection of Johnson/Cousins photometry for stars with known [Fe/H] is used to generate color-color relations that include the abundance dependence. Literature temperature and bolometric correction (BC) dependences are attached to the color relations. The JHK colors are transformed to the Bessell & Brett homogenized system. The main result of this work is the tabulation of seven colors and the V-band BC as a function of T eff, log g, and [Fe/H] for -1.06 < V - K < 10.2 and an accompanying interpolation program. Improvements to the present calibration would involve filling photometry gaps, obtaining more accurate and on-system photometry, knowing better log g and [Fe/H] values, improving the statistics for data-impoverished groups of stars such as metal-poor K dwarfs, applying small tweaks in the processing pipeline, and obtaining better empirical temperature and BC relations, especially for supergiants and M stars. A way to estimate dust extinction from M dwarf colors is pointed out. © 2011. The American Astronomical Society. All rights reserved.

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Natural And Drought Scenarios In An East Central Amazon Forest: Fidelity Of The Community Land Model 3.5 With Three Biogeochemical Models, Koichi Sakaguchi, Xubin Zeng, Bradley O. Christoffersen, Natalia Restrepo-Coupe, Scott R. Saleska, Paulo M. Brando Mar 2011

Natural And Drought Scenarios In An East Central Amazon Forest: Fidelity Of The Community Land Model 3.5 With Three Biogeochemical Models, Koichi Sakaguchi, Xubin Zeng, Bradley O. Christoffersen, Natalia Restrepo-Coupe, Scott R. Saleska, Paulo M. Brando

School of Integrative Biological & Chemical Sciences Faculty Publications

Recent development of general circulation models involves biogeochemical cycles: flows of carbon and other chemical species that circulate through the Earth system. Such models are valuable tools for future projections of climate, but still bear large uncertainties in the model simulations. One of the regions with especially high uncertainty is the Amazon forest where large-scale dieback associated with the changing climate is predicted by several models. In order to better understand the capability and weakness of global-scale land-biogeochemical models in simulating a tropical ecosystem under the present day as well as significantly drier climates, we analyzed the off-line simulations for …

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Academic And Social Aspects Of Recent Immigrant Children's School Experiences In A Public Elementary School In A U.S.- Mexico Border Town In South Texas, Alicia Judith Bolt Mar 2011

Academic And Social Aspects Of Recent Immigrant Children's School Experiences In A Public Elementary School In A U.S.- Mexico Border Town In South Texas, Alicia Judith Bolt

Theses and Dissertations - UTB/UTPA

In this study I examined school experiences of recent immigrant students who came to the Ollin South elementary school in Texas, U.S., with prior schooling in Yolitzli, Tamaulipas, Mexico. Using an ethnographic perspective, I analyzed how children and their parents and teachers described children's schooling experiences, challenges, and transition processes. I conducted semi-structured and open-ended interviews with ten students enrolled in 1st through 5th grade in a public elementary school in Ollin, Texas. I also interviewed the parents and teachers of the students to gain a broader perspective of student experiences and schooling processes on both sides of the border. …

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Proof System Representations Of Degrees Of Disjoint Np-Pairs, Liyu Zhang Mar 2011

Proof System Representations Of Degrees Of Disjoint Np-Pairs, Liyu Zhang

Computer Science Faculty Publications

Let D be a set of many-one degrees of disjoint NP-pairs. We define a proof system representation of D to be a set of propositional proof systems P such that each degree in D contains the canonical NP-pair of a corresponding proof system in P and the degree structure of D is reflected by the simulation order among the corresponding proof systems in P. We also define a nesting representation of D to be a set of NP-pairs S such that each degree in D contains a representative NP-pair in S and the degree structure of D is reflected by …

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The Collegian (2011-02-28), Christine Cavazos Feb 2011

The Collegian (2011-02-28), Christine Cavazos

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 63, No. 21

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The Collegian (2011-02-21), Christine Cavazos Feb 2011

The Collegian (2011-02-21), Christine Cavazos

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 63, No. 20

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The Pan American (2011-02-10), Kristen Cabrera Feb 2011

The Pan American (2011-02-10), Kristen Cabrera

UTPA Archives - The Pan American Newspaper

Vol. 67, No. 17

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Soil Nitrogen Transformations Under Elevated Atmospheric Co2 And O3 During The Soybean Growing Season, Engil Isadora Pujol Pereira, Haegeun Chung, Kate Scow, Michael J. Sadowsky, Chris Van Kessel Feb 2011

Soil Nitrogen Transformations Under Elevated Atmospheric Co2 And O3 During The Soybean Growing Season, Engil Isadora Pujol Pereira, Haegeun Chung, Kate Scow, Michael J. Sadowsky, Chris Van Kessel

School of Earth, Environmental, & Marine Sciences Faculty Publications

We investigated the influence of elevated CO2 and O3 on soil N cycling within the soybean growing season and across soil environments (i.e., rhizosphere and bulk soil) at the Soybean Free Air Concentration Enrichment (SoyFACE) experiment in Illinois, USA. Elevated O3 decreased soil mineral N likely through a reduction in plant material input and increased denitrification, which was evidenced by the greater abundance of the denitrifier gene nosZ. Elevated CO2 did not alter the parameters evaluated and both elevated CO2 and O3 showed no interactive effects on nitrifier and denitrifier abundance, nor on total and mineral N concentrations. These results …

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Search For Gravitational Waves Associated With The August 2006 Timing Glitch Of The Vela Pulsar, J. Abadie, B. P. Abbott, R. Abbott, R. Adhikari, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya Mohanty, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano Feb 2011

Search For Gravitational Waves Associated With The August 2006 Timing Glitch Of The Vela Pulsar, J. Abadie, B. P. Abbott, R. Abbott, R. Adhikari, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya Mohanty, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano

Physics & Astronomy Faculty Publications

The physical mechanisms responsible for pulsar timing glitches are thought to excite quasinormal mode oscillations in their parent neutron star that couple to gravitational-wave emission. In August 2006, a timing glitch was observed in the radio emission of PSR B0833-45, the Vela pulsar. At the time of the glitch, the two colocated Hanford gravitational-wave detectors of the Laser Interferometer Gravitational-wave observatory (LIGO) were operational and taking data as part of the fifth LIGO science run (S5). We present the first direct search for the gravitational-wave emission associated with oscillations of the fundamental quadrupole mode excited by a pulsar timing glitch. …

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The Collegian (2011-01-31), Christine Cavazos Jan 2011

The Collegian (2011-01-31), Christine Cavazos

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 63, No. 17

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Mathematical Modeling And Computation Of Channel Flow Over Discrete Structures, Rolando J. Olivares, Daniel N. Riahi Jan 2011

Mathematical Modeling And Computation Of Channel Flow Over Discrete Structures, Rolando J. Olivares, Daniel N. Riahi

School of Mathematical & Statistical Sciences Faculty Publications

In this paper mathematical modeling and computation of channel flow over small discrete structures are carried out under some reasonable conditions. A mathematical model for such a flow problem, which is based on a relevant system of partial differential equations and Fourier analysis, is studied using perturbation and nonlinear stability methods, and the resulting flow solutions over two types of discrete structures are computed under both stable and unstable conditions. It was found, in particular, that for a subcritical domain with the Reynolds number R slightly less than its critical value Rc, which is defined as the value below which …

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The Collegian (2011-01-24), Christine Cavazos Jan 2011

The Collegian (2011-01-24), Christine Cavazos

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 63, No. 16

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Temperature 1 Self-Assembly: Deterministic Assembly In 3d And Probabilistic Assembly In 2d, Matthew Cook, Yunhui Fu, Robert Schweller Jan 2011

Temperature 1 Self-Assembly: Deterministic Assembly In 3d And Probabilistic Assembly In 2d, Matthew Cook, Yunhui Fu, Robert Schweller

Computer Science Faculty Publications

We investigate the power of the Wang tile self-assembly model at temperature 1, a threshold value that permits attachment between any two tiles that share even a single bond. When restricted to deterministic assembly in the plane, no temperature 1 assembly system has been shown to build a shape with a tile complexity smaller than the diameter of the shape. In contrast, we show that temperature 1 self-assembly in 3 dimensions, even when growth is restricted to at most 1 step into the third dimension, is capable of simulating a large class of temperature 2 systems, in turn permitting the …

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The Collegian (2011-01-17), Christine Cavazos Jan 2011

The Collegian (2011-01-17), Christine Cavazos

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 63, No. 15

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Phosphoric Acid Catalyzed Aza-Michael Reaction In Water: An Ecofriendly Procedure, Debasish Bandyopadhyay, Stephanie Maldonado, Bimal K. Banik Jan 2011

Phosphoric Acid Catalyzed Aza-Michael Reaction In Water: An Ecofriendly Procedure, Debasish Bandyopadhyay, Stephanie Maldonado, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Phosphoric acid catalyzed aza-Michael reaction in water has been carried out in an efficient manner at room temperature. The reaction is general for primary, secondary (cyclic, heterocyclic and acyclic), benzylic as well as aromatic amines. No bis-addition was observed for primary amines.

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Utb/Tsc Commencement – Winter 2011, University Of Texas At Brownsville, Texas Southmost College Jan 2011

Utb/Tsc Commencement – Winter 2011, University Of Texas At Brownsville, Texas Southmost College

Brownsville Archives - Legacy Commencement Programs

No abstract provided.

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Utb/Tsc Legacy Degree Programs And Courses 2011 – 2012, University Of Texas At Brownsville, Texas Southmost College Jan 2011

Utb/Tsc Legacy Degree Programs And Courses 2011 – 2012, University Of Texas At Brownsville, Texas Southmost College

UTB/TSC Archives - Course Catalogs

No abstract provided.

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Utpa Graduate School Student Handbook 2011-2013, University Of Texas-Pan American Jan 2011

Utpa Graduate School Student Handbook 2011-2013, University Of Texas-Pan American

Student Handbooks (UTB/UTPA)

No abstract provided.

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Utpa Graduate Catalog 2011-2013, University Of Texas Pan American Jan 2011

Utpa Graduate Catalog 2011-2013, University Of Texas Pan American

UTPA Archives - Course Catalogs

No abstract provided.

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Utb/Tsc Graduate Catalog 2011-2013, University Of Texas At Brownsville, Texas Southmost College Jan 2011

Utb/Tsc Graduate Catalog 2011-2013, University Of Texas At Brownsville, Texas Southmost College

UTB/TSC Archives - Course Catalogs

No abstract provided.

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Utb/Tsc Undergraduate Catalog 2011-2012, University Of Texas At Brownsville, Texas Southmost College Jan 2011

Utb/Tsc Undergraduate Catalog 2011-2012, University Of Texas At Brownsville, Texas Southmost College

UTB/TSC Archives - Course Catalogs

No abstract provided.

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Utpa Undergraduate Catalog 2011-2013, University Of Texas Pan American Jan 2011

Utpa Undergraduate Catalog 2011-2013, University Of Texas Pan American

UTPA Archives - Course Catalogs

No abstract provided.

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