Digital Commons Network^™

Artificial Lateral Line Canal For Hydrodynamic Detection, Yingchen Yang, Adrian Klein, Horst Bleckmann, Chang Liu

Mechanical Engineering Faculty Publications

Fish use their lateral line system to detect minute water motions. The lateral line consists of superficial neuromasts and canal neuromasts. The response properties of canal neuromasts differ from those of superficial ones. Here, we report the design, fabrication, and characterization of an artificial lateral line canal system. The characterization was done under various fluid conditions, including dipolar excitation and turbulent flow. The experimental results with dipole excitation match well with a mathematical model. Canal sensors also demonstrate significantly better noise immunity compared with superficial ones. Canal-type artificial lateral lines may become important for underwater flow sensing.

Orange & White - Summer 2011, University Of Texas At Brownsville, Texas Southmost College

UTB/TSC Archives - Orange & White Magazine

No abstract provided.

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

Edinburg Archives - Legacy Commencement Programs

No abstract provided.

Comparison Of Soil Chemistry And Microbial Communities That Inhabit The Rhizosphere Of Native And Non-Native Grasses Of The Lower Rio Grande Valley, Jacqueline Valencia

Theses and Dissertations - UTB/UTPA

Non-native grasses can modify the soils they invade. This study investigated microbial variation among native and non-native grasses in the Lower Rio Grande Valley. We hypothesized that rhizospheres of non-native grasses would support a higher density of microorganisms; therefore microbial communities of invasive plants would exploit more carbon sources than those of native plants. A second hypothesis stated that Streptomyces bacteria from the rhizosphere of non-native grasses would be better competitors. Samples of grasses, and soil from their respective rhizospheres were obtained in Arroyo City, TX. Results indicated a higher bacterial colony density, total activity and number of substrates utilized …

Near-Field Radiative Heat Transfer Between Macroscopic Planar Surfaces, R. S. Ottens, Volker Quetschke, Stacy Wise, A. A. Alemi, R. Lundock, G. Mueller, D. H. Reitze, D. B. Tanner, B. F. Whiting

Physics & Astronomy Faculty Publications

Near-field radiation allows heat to propagate across a small vacuum gap at rates several orders of magnitude above that of far-field, blackbody radiation. Although heat transfer via near-field effects has been discussed for many years, experimental verification of this theory has been very limited. We have measured the heat transfer between two macroscopic sapphire plates, finding an increase in agreement with expectations from theory. These experiments, conducted near 300K, have measured the heat transfer as a function of separation over mm to μm and as a function of temperature differences between 2.5 and 30K. The experiments demonstrate that evanescence can …

Search For Gravitational Wave Bursts From Six Magnetars, J. Abadie, B. P. Abbott, R. Abbott, M. Abernathy, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya D. Mohanty, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely 1kpc from Earth, an order of magnitude closer …

Search For Gravitational Waves From Binary Black Hole Inspiral Merger And Ringdown, J. Abadie, B. P. Abbott, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya Mohanty, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano

Physics & Astronomy Faculty Publications

We present the first modeled search for gravitational waves using the complete binary black-hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data, taken between November 2005 and September 2007, for systems with component masses of 1-99Mȯ and total masses of 25-100Mȯ. We did not detect any plausible gravitational-wave signals but we do place upper limits on the merger rate of binary black holes as a function of the component masses in this range. We constrain the rate of mergers for 19Mȯ≤m1, m 2≤28Mȯ binary black-hole …

A New Integrable Two-Component System With Cubic Nonlinearity, Junfeng Song, Changzheng Qu, Zhijun Qiao

School of Mathematical & Statistical Sciences Faculty Publications

In this paper, a new integrable two-component system, mt=[m(uxvx−uv+uvx−uxv)]x,nt=[n(uxvx−uv+uvx−uxv)]x, where m=u−uxx and n=v−vxx, is proposed. Our system is a generalized version of the integrable system mt=[m(u2x−u2)]x, which was shown having cusped solution (cuspon) and W/M-shape soliton solutions by Qiao [J. Math. Phys. 47, 112701 (2006). The new system is proven integrable not only in the sense of Lax-pair but also in the sense of geometry, namely, it describes pseudospherical surfaces. Accordingly, infinitely many conservation laws are derived through recursion relations. Furthermore, exact solutions such as cuspons and W/M-shape solitons are also obtained.

On Detection Of The Stochastic Gravitational-Wave Background Using The Parkes Pulsar Timing Array, D. R.B. Yardley, W. A. Coles, G. B. Hobbs, J. P.W. Verbiest, R. N. Manchester, W. Van Straten, Fredrick A. Jenet, M. Bailes, N. D.R. Bhat

Physics & Astronomy Faculty Publications

We search for the signature of an isotropic stochastic gravitational-wave background in pulsar timing observations using a frequency-domain correlation technique. These observations, which span roughly 12yr, were obtained with the 64-m Parkes radio telescope augmented by public domain observations from the Arecibo Observatory. A wide range of signal processing issues unique to pulsar timing and not previously presented in the literature are discussed. These include the effects of quadratic removal, irregular sampling and variable errors which exacerbate the spectral leakage inherent in estimating the steep red spectrum of the gravitational-wave background. These observations are found to be consistent with the …

Systematics Of Black Hole Binary Inspiral Kicks And The Slowness Approximation, Richard H. Price, Gaurav Khanna, Scott A. Hughes

Physics & Astronomy Faculty Publications

During the inspiral and merger of black holes, the interaction of gravitational wave multipoles carries linear momentum away, thereby providing an astrophysically important recoil, or “kick” to the system and to the final black hole remnant. It has been found that linear momentum during the last stage (quasinormal ringing) of the collapse tends to provide an “antikick” that in some cases cancels almost all the kick from the earlier (quasicircular inspiral) emission. We show here that this cancellation is not due to peculiarities of gravitational waves, black holes, or interacting multipoles, but simply to the fact that the rotating flux …

Ab Initio Description Of Nonlinear Dynamics Of Coupled Microdisk Resonators With Application To Self-Trapping Dynamics, Hamidreza Ramezani, Tsampikos Kottos, V. Shuvayev, L. Deych

Physics & Astronomy Faculty Publications

An ab initio approach is used to describe the time evolution of the amplitudes of whispering gallery modes in a system of coupled microdisk resonators with Kerr nonlinearity. It is shown that this system demonstrates a transition between Josephson-like nonlinear oscillations and self-trapping behavior. Manifestation of this transition in the dynamics of radiative losses is studied.

Asimafoetidnol: A New Sesquiterpenoid Coumarin From The Gum Resin Of Ferula Assa-Foetida, Debasish Bandyopadhyay, Manas Banerjee, Subrata Laskar, Bidyut Basak

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

Chemical investigation of the gum resin of Ferula assa-foetida L. resulted in the isolation of a new sesquiterpenoid coumarin, 7-(((E)-5-((1S,3S,6S)-3,6- dihydroxy-2,2,6-trimethylcyclohexyl)-3-methylpent-2-en-1-yl)oxy) -2H-chromen-2-one (asimafoetidnol), together with several other known compounds. The structure of asimafoetidnol was established on the basis of spectroscopic analyses. Geometry optimization of the compound has been carried out using a DFT/B3LYP/3-21G* method.

The Collegian (2011-05-02), Christine Cavazos

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 63, No. 28

In-Group Implicit Prejudice Against Mexican Americans In The Rio Grande Valley, Christelle Fabiola Garza

Theses and Dissertations - UTB/UTPA

The existence of in-group implicit prejudice against persons of Mexican origin was examined. Implicit refers to cognitive processes that the individual is unaware. Implicit attitudes are associations between social targets and positive or negative feelings that are passively learned from the environment. The measure we used to assess implicit prejudice was the Implicit Association Test. We also examined acculturation using the Acculturation Rating Scale for Mexican Americans (Flores-Niemann et al., 1999). Family values, assessed using the Cultural Values Scale (Unger, et al., 2002), and skin tone defined by light or dark complexion using a Photovolt 577 reflectance meter, were also …

Bismuth Nitrate-Induced Novel Nitration Of Eugenol And Estradiol: An Exploratory Study, Luis Canales

Theses and Dissertations - UTB/UTPA

Molecules originating in nature have held an important place in chemistry and in society. Many of the important useful compounds of all time were first discovered in nature. Eugenol, a multi-functionalized biologically active constituent, is present in high quantity in natural clove. Eugenol is an important herb due to its medicinal activities; therefore, research on this molecule is necessary. Nitration of Eugenol was performed through various metal nitrates and solid surface combinations. Estrogens are contributors of the development of many secondary sex characteristics in females; they play various important roles in the nervous system. Direct nitration of estradiol has been …

K-Hyponormality Of Powers Of Multivariable Weighted Shifts, Mayra O. Martinez

Theses and Dissertations - UTB/UTPA

In mathematics, weighted shifts, also known as shift operators or translation operators, are examples of linear operators. Single and multivariable weighted shifts have played an important role in the study of (joint) k-hyponormality to LPCS. They have also played a significant role in the study of cyclicity and reflexivity, in the study of C*-algebras generated by multiplication operators on Bergman spaces, as fertile ground to test new hypotheses, and as canonical models for theories of dilation and positivity. We will first consider the hyponormality of powers of commuting multivariable weighted shifts. Specifically, if we let W(α,β) := (T1, T2) denote …

Narrative Analysis And Computational Model To Predict Interestingness Of Narratives, Laxman Thapa

Theses and Dissertations - UTB/UTPA

In this research, I present results demonstrating the classification of the specially generated narratives by a machine agent by listening to human subject describing the same sets of the events. These classifications are based on human ratings of interestingness for many different recountings of the same stories. The classification is performed on various features selected after analyzing the different possible feature that affect on the interestingness of narratives. The features were extracted from the surface text as well as from annotations of how each narration relates to the content of the known story. I present the annotation process and resulting …

Synthesis And Characterization Of 4,4-Prime-Distyrylbiphenyl And Its Applications In Organic Field Effect Transistors, Nestor A. Santos Jr.

Theses and Dissertations - UTB/UTPA

4,4’-distyrylbiphenyl (DSBP), an ambipolar small molecule with electroluminescent properties, was synthesized following two synthetic protocols. Accordingly, biphenyl was bromomethylated using a mixture of paraformaldehyde and hydrogen bromide in 20% to 60% isolated yields. Bromomethylated biphenyl was then reacted with triphenyl phosphine, or with triethyl phosphate to yield the corresponding triphenyl phosphonium bromide or triethyl phosphonate, respectively. DSBP was synthesized by reaction of the triphenyl phosphonium bromide or triethyl phosphonate with freshly distilled benzaldehyde according to the Wittig, or Horner-Wadsworth-Emmons protocols. DSBP from the Wittig reaction resulted in a mixture of cis-trans isomers, while the product from the Horner-Wadsworth-Emmons reaction yielded …

Essays On The Dynamics Of Stock Returns In Emerging Markets: Roles Of Volatility And Sentiment In Turkey, Sidika Gülfem Bayram

Theses and Dissertations - UTB/UTPA

Emerging stock markets play an important role in portfolio diversification. Accurate depiction of their status is essential for potential investment assessment. This dissertation focuses on two important aspects of emerging markets using Istanbul Stock Exchange (“ISE”) as an example: modeling stock return volatility as a measure of risk and exploring potential interaction between stock returns and consumer/business sentiments. ISE is selected as it has no entry restrictions and offers great investment potential with 65% foreign participation.

The first essay focuses on stock return volatility. Potential asymmetric behavior is investigated by looking into how the ISE National-100 Index prices evolve over …

Biocompatibility Of Electrospun Polymer Nanofibers (Epns) With Nih 3t3 Cell Line And Interaction Of Quercetin With Different Flavonoids: Induction Of Phase Ii Enzymes In Vitro Cancer Cell Lines, Brenda S. Benavides

Theses and Dissertations - UTB/UTPA

Part I: In this study Electrospun nanofibers, Elasthane™ 55D, Elasthane™ 75D, Biospan®, Hydrothane™ and Lycra® were evaluated for their biocompatibility to be artificial tissue substitutes using NIH-3T3 fibroblast cells. A colorimetric based MTT dye reduction assay demonstrated that EPNs did not stop cell growth in vitro. Additionally, fluorescence confocal microscope images verified that cell adhesion occurred in the nanofibers, and cell growth on the EPNs over two weeks period was confirmed by DNA quantification.

Part II: This section of the thesis is focused on evaluation of chemopreventive properties of various phytochemicals by induction of Phase II enzymes. The interaction of …

Duffing-Van Der Pol-Type Nonlinear Oscillator System, Jing Cui

Theses and Dissertations - UTB/UTPA

In this thesis, we are concerned with the nonlinear Duffing–van der Pol–type oscillator system by means of the Lie symmetry reduction method. This system has physical relevance as a simple model in certain flow-induced structural vibration problems, which includes the van der Pol oscillator and the damped Duffing oscillator etc as particular cases. By applying the Lie symmetry analysis, we find two nontrivial infinitesimal generators, and use them to construct canonical variables. Through the inverse analysis, some dynamical properties of the nonlinear system under certain parametric conditions are presented. Comparison with the existing results by the Prelle– Singer procedure is …

At-Risk Hispanic Students' Perception Of Afterschool Programs: A New Model Targeting The Needs Of English Language Learners, Cynthia Wise Galvan

Theses and Dissertations - UTB/UTPA

The purpose of this study was to explore 21st Century Community Learning Centers (CCLC) as support systems for at-risk Hispanic youth. Expanding upon previous theories that analyzed afterschool programs and bilingual programs separately, this study sought to understand how 3rd, 4th and 5th grade at-risk Hispanic youth attending the 21st CCLC, Afterschool Centers on Education, perceive the afterschool programs in a small school district in South Texas. The study analyzed five afterschool program constructs pertaining to what literature says are best practices for afterschool programs and bilingual programs inclusive of safety, self-esteem, interactive, and engaging, language, and cultural characteristics. This …

A Case Study Of Spanish Language Use In A Texas Border Colonia, Maria E. Diaz

Theses and Dissertations - UTB/UTPA

This case study reveals a Spanish language marginalization in a South Texas community of mostly Latinos, who are the fastest growing group in the U.S. (Colombi & Roca, 2003); furthermore, approximately 77% of English language learners (ELLs) have Spanish as their heritage language (Hopstock & Stephenson, 2003). Nevertheless, ELLs do not receive much academic literacy support in their first language in many schools (Zehler et al., 2003). Thus, out-of- school social practices play an important role on maintaining a native language (e.g., Burrows-Goodwill, 2009; Reyes, 2006). However, researchers have not explored this phenomenon in Texas border colonias, or unincorporated areas …

Soliton Solutions Of Ultradiscrete Integrable Systems, Wei Yin

Theses and Dissertations - UTB/UTPA

In recent years, ultradiscrete integrable systems, in which both independent and dependent variables are discretized, have attracted much attention. In this thesis, we show how to obtain all line soliton solutions of (2+1)-dimensional ultradiscrete soliton systems from determinant solutions of discrete soliton systems by taking an ultradiscrete limit. Taking an ultradiscrete limit of determinant solutions with non-negativity, we obtain Casorati determinant-like solutions. Starting from Grammian (Gram-type determinant), we obtain another expression of τ-functions, which leads to a perturbed form after the expansion of Grammian. These two different forms are essentially equivalent, i.e., it is possible to transform a form into …

Partition A 3-Colorable Graph Into A Small Bipartite Subgraph And A Large Independent Set, Qing Wang

Theses and Dissertations - UTB/UTPA

Exact algorithms have made a little progress for the 3-coloring problem: improved from to since 1976. The best exact algorithm for the 3-coloring problem is by Beigel and Eppstein, and its analysis is very complicated. We study the parameterized 3-coloring problem: partitioning a 3-colorable graph into a bipartite subgraph and an independent set. Taking the size of the bipartite subgraph as the parameter k, we propose the first parameter algorithm of complexity . Our algorithm can solve the 3-coloring problem faster than the best exact algorithm for graphs with k ≤ 0.527n where n is the graph size. Our study …

Distributed Semantic Web Data Management In Hbase And Mysql Cluster, Craig M. Franke

Theses and Dissertations - UTB/UTPA

Various computing and data resources on the Web are being enhanced with machine-interpretable semantic descriptions to facilitate better search, discovery and integration. This interconnected metadata constitutes the Semantic Web, whose volume can potentially grow the scale of the Web. Efficient management of Semantic Web data, expressed using the W3C's Resource Description Framework (RDF), is crucial for supporting new data-intensive, semantics-enabled applications. In this work, we study and compare two approaches to distributed RDF data management based on emerging cloud computing technologies and traditional relational database clustering technologies. In particular, we design distributed RDF data storage and querying schemes for HBase …

Arecibo Palfa Survey And Einstein@Home: Binary Pulsar Discovery By Volunteer Computing, B. Knispel, P. Lazarus, B. Allen, D. Anderson, C. Aulbert, N. D.R. Bhat, O. Bock, S. Bogdanov, A. Brazier, Fredrick A. Jenet

Physics & Astronomy Faculty Publications

We report the discovery of the 20.7ms binary pulsar J1952+2630, made using the distributed computing project Einstein@Home in Pulsar ALFA survey observations with the Arecibo telescope. Follow-up observations with the Arecibo telescope confirm the binary nature of the system. We obtain a circular orbital solution with an orbital period of 9.4hr, a projected orbital radius of 2.8lt-s, and a mass function of f = 0.15 M ⊙ by analysis of spin period measurements. No evidence of orbital eccentricity is apparent; we set a 2σ upper limit e ≲ 1.7 × 10 -3 . The orbital parameters suggest a massive white …

The Pan American (2011-04-28), Kristen Cabrera

UTPA Archives - The Pan American Newspaper

Vol. 67, No. 26

The Collegian (2011-04-25), Christine Cavazos

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 63, No. 27

The Collegian (2011-04-11), Christine Cavazos

UTB/TSC Archives - The Collegian [Newspaper]

Vol. 63, No. 25