Global ETD Search

621	Optofluidic Manipulation with Nanomembrane Platforms Used for Solid-State Nanopore Integration Walker, Zachary J. 16 June 2022 (has links) (PDF) Nanopore technology has introduced new techniques for single particle detection and analysis. A nanopore consists of a small opening in a membrane on the nanometer scale. Nanopores are found in nature and are utilized for transporting molecules through biological membranes. Researchers have been able to mimic naturally forming biological nanopores and utilize them for a variety of sensing applications. Nanopores, fabricated either organically or inorganically, can be used for detecting biomarkers such as proteins, nucleic acids, and metabolites that translocate the membrane by way of the nanopore. Constant ionic current flow is measured through the nanopore by way of a sensitive ammeter. In the presence of a biomarker, the ionic current flow will be impeded, causing the electrical signal to drop. This drop uniquely corresponds to the type of particle passing through the nanopore. In this work, the thin membrane on which the nanopore resides is created through a newly developed meniscus shaped sacrificial technique. The sacrificial polymer material starts as a liquid and is confined to the microfluidic channel through the capillary effect, giving it the meniscus profile. It is used as a structural support on which a thin silicon dioxide layer is grown. The layer of oxide takes on the same natural meniscus shape as the sacrificial material. The polymer is subsequently etched, resulting in a hollow core liquid channel with a suspended meniscus membrane. This process allows a thin membrane to be fabricated on top of a microfluidic channel that ranges from 50-200 nm in thickness. The meniscus membrane is crucial to the success of nanopore formation. The nanoscale membrane allows for smaller, more precise nanopores to be created. Reduced nanopore dimensions are advantageous for the detection of smaller biomarkers. The platform described in this dissertation integrates solid-state naturally forming meniscus membranes with solid-core and optofluidic waveguides for nanopore detection applications. The waveguides allow for a particle trap to be introduced to the system. The ability to trap particles directly under the nanopore is critical to the speed of which the nanopore can operate. This dissertation focuses on the fabrication, characterization, and testing of an optofluidic platform that features a nanopore for rapid single molecule detection and analysis. Zachary J. Walker Aaron Hawkins nanopore micropore optofluidics microfluidics single-molecule analysis biosensor lab-on-a-chip integrated optics ARROW natural meniscus membrane ionic current flow optical trap physical trap Engineering
622	Development and Characterization of an Underwater Acoustics Laboratory Via in situ Impedance Boundary Measurements Vongsawad, Cameron Taylor 20 December 2021 (has links) Modeling underwater acoustic propagation comes with a variety of challenges due to the need for proper characterization of the environmental conditions. These conditions include ever changing and complex water properties as well as boundary conditions. The BYU underwater acoustics open-air tank test-bed and measurement chain were developed to study underwater acoustic propagation within a controlled environment. It was also developed to provide ways to test and validate ocean models without the high cost associated with obtaining open ocean measurements. However, tank measurements require additional characterization of boundary conditions associated with the walls of the tank which would not be present in an open ocean. The characterization of BYU's underwater acoustic tank included measuring the calibrated impulse response of the tank through frequency deconvolution of sine swept signals in order to determine the frequency dependent reverberation time through reverse Schroeder integration. The reverberation time allows for calculating the frequency dependent spatially averaged acoustic absorption coefficient of the tank enclosure boundaries. The methods used for this study, common to room acoustics, also yield insights into the Schroeder frequency limit of the tank as well as validate models used for quantifying the speed of sound in the tank. The acoustic characterization was validated alongside predicted values and also applied to a tank lined with anechoic panels in order to improve the potential for modeling the tank as a scaled open ocean environment. An initial investigation into effective tank models evaluated the idealized rigid-wall and pressure-release water-air boundary model, a finite-impedance boundary model applying the measured acoustic boundary absorption and a benchmark open ocean model known as ORCA in order to determine potential tank model candidates. This study demonstrates the efficacy of the methodology for underwater acoustic tank characterization, provides a frequency dependent acoustic boundary evaluation from 5-500 kHz, and provides an initial comparison of tank models with applied characterization. acoustic anechoic panels boundary absorption characterization deconvolution finite-impedance boundary in situ calibration lab design normal-mode waveguide modeling reverberation time Schroeder frequency through the sensor ultrasonic acoustic propagation underwater acoustics water tank Physical Sciences and Mathematics
623	Black Like Me: The Malleability of African American Political Racial Group Identification Laird, Chryl Nicole 25 September 2014 (has links) No description available. Political Science African American Studies African Americans African American politics Black politics Race and Ethnic Politics linked fate political communication field experiments lab experiments survey research political psychology political behavior public opinion political attitudes
624	Adaptive Optics System Baseline Modeling for a USAF Quad Axis Telescope Morris, Nathaniel R. 07 September 2017 (has links) No description available. Astronomy Atmosphere Atmospheric Sciences Engineering Optics Physics Adaptive Optics John Bryan Observatory Atmospheric Turbulence Compensation LIDAR Air Force Research Lab Fried Parameter Greenwood Frequency Rytov Number Baseline specifications for AO system
625	Development of an undergraduate laboratory course in control systems Abiakel, Elio January 2003 (has links) No description available. Control Systems Lab Control Laboratory EE557 dSPACE Quanser Simulink Matlab root locus feedback control signals and systems Helicopter control flexible link flexible joint DC servo, servomotor speed control position control
626	<b>Reprogramming the Pancreatic Cancer Stroma by Targeting Coagulation at the Tumor Microenvironment</b> Sae Rome Choi (18392505) 17 April 2024 (has links) <p dir="ltr">Pancreatic ductal adenocarcinoma (PDAC) remains one of the most deadliest cancer and despite advancements in cancer therapy, remain highly refractory to treatment, largely due to its desmoplastic tumor microenvironment (TME) characterized by complex interactions among cancer cells and stromal components. Particularly, the PDAC associated coagulation system due to leaky tumor vasculatures plays a pivotal role in reshaping the PDAC stroma and its pathogenesis. Understanding the intricate interplay between tumor cells, stromal cells, and the elevated coagulation pathway elements, including tissue factor, thrombin, and fibrin, is essential for developing effective therapeutic strategies. To address these challenges, this research proposes the engineering of a novel PDAC-associated coagulation system using a microfluidic technology, known as coagulation-on-tumor-microenvironment-on-chip (cT-MOC). The study aims to integrate key coagulation pathways in cT-MOC to investigate pivotal interactions in the PDAC stroma: <i>i)</i> thrombin-protease-activated receptors (PARs) mediated promotion of PDAC fibrosis via activation of cancer-fibroblast cross-talk; <i>ii)</i> in-depth analysis of transport and mechanical properties of collagen-fibrin microstructure; <i>iii)</i> inhibited drug delivery in reprogrammed PDAC stroma due to pronounced fibrin deposition on collagen. By leveraging innovative microfluidic technologies and comprehensive experimental approaches, the research endeavors to provide a novel platform that bridges traditional <i>in vitro</i> and <i>in vivo</i> models to overcome the challenges posed by the desmoplastic TME and enhance therapeutic strategies for treatment by targeting the coagulation at the PDAC TME.</p> Cancer cell biology Cancer diagnosis Chemotherapy Solid tumours Biofabrication Biomaterials Biomechanical engineering Tissue engineering pancreatic adenocarcinoma cancer ce... lab on-a-chip device preclinical cancer models Tissue engineered cell culture models drug delivery & targeting
627	First Time Measurements of Polarization Observables for the Charged Cascade Hyperon in Photoproduction Bono, Jason S 06 June 2014 (has links) The parity violating weak decay of hyperons offers a valuable means of measuring their polarization, providing insight into the production of strange quarks and the matter they compose. Jefferson Lab’s CLAS collaboration has utilized this property of hyperons, publishing the most precise polarization measurements for the Λ and Σ in both photoproduction and electroproduction to date. In contrast, cascades, which contain two strange quarks, can only be produced through indirect processes and as a result, exhibit low cross sections thus remaining experimentally elusive. At present, there are two aspects in cascade physics where progress has been minimal: characterizing their production mechanism, which lacks theoretical and experimental developments, and observation of the numerous excited cascade resonances that are required to exist by flavor SU(3)F symmetry. However, CLAS data were collected in 2008 with a luminosity of 68 pb−1 using a circularly polarized photon beam with energies up to 5.45 GeV, incident on a liquid hydrogen target. This dataset is, at present, the world’s largest for meson photoproduction in its energy range and provides a unique opportunity to study cascade physics with polarization measurements. The current analysis explores hyperon production through the γp → K+K+Ξ− reaction by providing the first ever determination of spin observables P, Cx and Cz for the cascade. Three of our primary goals are to test the only cascade photoproduction model in existence, examine the underlying processes that give rise to hyperon polarization, and to stimulate future theoretical developments while providing constraints for their parameters. Our research is part of a broader program to understand the production of strange quarks and hadrons with strangeness. The remainder of this document discusses the motivation behind such research, the method of data collection, details of their analysis, and the significance of our results. Physics Weak Nuclear Polarization Hyperon Particle Baryon Meson Strange Quark Kaon Photoproduction Jlab Jefferson Lab Photon Lambda Production Gamma K P Xi Cascade Jason Bono Experimental Accelerator g12 CLAS Jason Bono Jason S. Bono Nuclear Physics Particle Physics Hyperon Polarization Weak Decay Cascade Polarization Xi Polarization Induced Transfered Cx Cz Induced Polarization Transfered Polarization FIU Jlab Jefferson Lab Hall b
628	Návrh metody pro testování elektricky asistovaných turbodmychadel / Design of Calculation Method for Electrically Assisted Turbochargers Staněk, Lukáš January 2013 (has links) The Diploma thesis deals with the testing of electrically assisted turbochargers. Aim of this work is to apply the established way of the performance testing of conventional turbochargers for electrically assisted turbocharger. Part of this work is to create a program for the calculation of the observed characteristics of the turbocharger. The program is extended to the characteristics of the generator for electrically assisted turbocharger. The program will serve as a basic for control the data for tested motorsport applications.
629	An analysis of phonotactic behaviour in the cricket Gryllus bimaculatus Sarmiento-Ponce, Edith Julieta January 2019 (has links) This thesis represents a comprehensive examination of the phonotactic behaviour (i.e. attraction to sound) of the female Gryllus bimaculatus under laboratory conditions. Chapter 2 is the first study to analyze the effect of substrate texture on walking performance in crickets. Substrate texture is found to play an essential role in the phonotactic responses of G. bimaculatus. Smooth substrate texture has a detrimental effect due to slipping, whereas a rough texture results in optimal walking performance due to the friction with the walking legs. Chapter 3 represents the first detailed lifetime study analysing phonotaxis in crickets. My results demonstrate that the optimal age to test phonotaxis in G. bimaculatus females is from day 7 to 24 after the final moult. I also found that selectiveness was persistent with age. These findings contradict the female choosiness hypothesis. This study is also the first to describe the effect of senescence on phonotaxis in insects, as responsiveness decreases with age. Chapter 4 compares the phonotactic behaviour of female crickets from different laboratory-bred colonies. From six tested cricket lab colonies, I found three groups statistically different from each other. Females raised under laboratory conditions at the University of Cambridge and Anglia Ruskin University were most reponsive at a frequency of 4.5 kHz, whereas females bred in Tokushima University in Japan were tuned towards a higher frequency of 5 kHz. These results suggest a degree of artificial allopatric speciation. Comparisons with crickets bred under low-quality conditions in a local pet shop demonstrate a loss of responsiveness, indicating that breeding conditions have a direct effect on phonotactic responsivity. Chapter 5 is the first study to report the presence of phonotaxis in males of G. bimaculatus. Previously it was unknown if G. bimaculatus males were able to perform phonotaxis, given that they were only recognised as endurance signal producers. In the present study, only 20% of the studied males (N=70) performed a weak phonotactic response. This finding has potential ecological implications in terms of male cricket territory establishment, and male-male interactions in the wild, which are discussed. Chapter 6 explores the song pattern recognition of the female G. bimaculatus by changing the duration of either the first, second or third pulse of the chirps. A long first pulse decreased the phonotactic response whereas phonotaxis remained strong when the third pulse was long. Chirps with three pulses of increasing duration of 5, 20 and 50 ms elicited phonotaxis, but the chirps were not attractive when played in reverse order. The data are in agreement with a mechanism in which processing of a sound pulse has an effect on the processing of the subsequent pulse, as outlined in the flow of activity in a delay-line and coincidence-detector circuit.
630	A Treatise on the Geometric and Electronic Structure of Clusters : Investigated by Synchrotron Radiation Based Electron Spectroscopies Lindblad, Andreas January 2008 (has links) <p>Clusters are finite ensembles of atoms or molecules with sizes in the nanometer regime (<i>i.e.</i> nanoparticles). This thesis present results on the geometric and electronic structure of homogeneous and heterogeneous combinations of atoms and molecules. The systems have been studied with synchrotron radiation and valence, core and Auger electron spectroscopic techniques.</p><p>The first theme of the thesis is that of mixed clusters. It is shown that by varying the cluster production technique both structures that are close to that predicted by equilibrium considerations can be attained as well as far from equilibrium structures.</p><p>Electronic processes following ionization constitute the second theme. The post-collision interaction phenomenon, energy exchange between the photo- and the Auger electrons, is shown to be different in clusters of argon, krypton and xenon. A model is proposed that takes polarization screening in the final state into account. This result is of general character and should be applicable to the analysis of core level photoelectron and Auger electron spectra of insulating and semi-conducting bulk materials as well.</p><p>Interatomic Coloumbic Decay is a process that can occur in the condensed phases of weakly bonded systems. Results on the time-scale of the process in Ne clusters and mixed Ar/Ne clusters are herein discussed, as well observations of resonant contributions to the process. In analogy to Auger <i>vis-à-vis</i> Resonant Auger it is found that to the ICD process there is a corresponding Resonant ICD process possible. This has later been observed in other systems and by theoretical calculations as well in subsequent works by other groups.</p><p>Delocalization of dicationic valence final states in the hydrogen bonded ammonia clusters and aqueous ammonia has also been investigated by Auger electron spectroscopy. With those results it was possible to assign a previously observed feature in the Auger electron spectrum of solid ammonia.</p> Cluster nanoparticle Heterogeneous Homogeneous Mixed Cluster production methods co-expansion pick-up doping Cluster geometry radial segregation Interatomic Coulombic Decay ICD Auger electron spectroscopy AES X-ray photoelectron spectroscopy XPS Ultra-violet spectroscopy UPS Noble gas Rare gas Ne Ar Kr Xe Ammonia NH3 Sulphur hexafluoride SF6 MAX-lab BESSY Physics Fysik

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