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Full-Text Articles in Physics
Direct Parameter Fitting Of Action Potentials In Skeletal Muscle Cells Which Include Longitudinal Segments, Tyme Suda
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Excitation of skeletal muscle cells triggers a large voltage spike known as an action potential (AP), leading to muscle contraction. Modeling of an AP is typically done using the method developed by scientists Hodgkin and Huxley (HH). In the HH method, voltage and time gated Na+ and K+ ionic currents are simulated, along with a positive “Leak” ionic current and capacitive current. Due to the complexity and the computational time required for simulation, direct fitting of HH parameters to experimental APs has rarely been attempted. A previous thesis at Wright State performed direct fitting for the case of a single …
Using Network Analysis To Contrast Three Models Of Student Forum Discussions, Hannah N. Benston
Using Network Analysis To Contrast Three Models Of Student Forum Discussions, Hannah N. Benston
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There is much research about how actors and events in social networks affect each other. In this research, three network models were created for discussion forums in three semesters of undergraduate general physics courses. This study seeks to understand what social network measures are most telling of a online forum classroom dynamic. That is, I wanted to understand more about things like what students are most central to the networks and whether this is consistent across different network models. I also wanted to better understand how students may or may not group together. What relationships (student to student, student to …
Establishing A Machine Learning Framework For Discovering Novel Phononic Crystal Designs, Drew Feltner
Establishing A Machine Learning Framework For Discovering Novel Phononic Crystal Designs, Drew Feltner
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A phonon is a discrete unit of vibrational motion that occurs in a crystal lattice. Phonons and the frequency at which they propagate play a significant role in the thermal, optical, and electronic properties of a material. A phononic material/device is similar to a photonic material/device, except that it is fabricated to manipulate certain bands of acoustic waves instead of electromagnetic waves. Phononic materials and devices have been studied much less than their photonic analogues and as such current materials exhibit control over a smaller range of frequencies. This study aims to test the viability of machine learning, specifically neural …
The Effects Of An Ultrafast Pulsed Laser On Ybco Thin Film Circuit Transients, Matthew L. Rustad
The Effects Of An Ultrafast Pulsed Laser On Ybco Thin Film Circuit Transients, Matthew L. Rustad
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Terahertz (THz) frequency light has shown promise for a wide variety of applications due to its material characterization and imaging capabilities. Its nondestructive nature coupled with its submillimeter spatial resolution provides the most value for terahertz light as an imaging tool. The application of terahertz technology has been limited by a lack of novel and powerful sources. It has been shown that that Yttrium Barium Copper Oxide (YBCO), a type II superconductor, has certain properties that would allow YBCO to be an effective source for THz light. Recent microwave work has shown that when a persistent supercurrent is placed on …
Finite Different Time-Domain Simulation Of Terahertz Waves Propagation Through Unmagnetized Plasma, Aditha Srikantha Senarath
Finite Different Time-Domain Simulation Of Terahertz Waves Propagation Through Unmagnetized Plasma, Aditha Srikantha Senarath
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In order to support ongoing terahertz time-domain spectroscopic experiments involving plasma characterization, it is beneficial to simulate the interaction of THz pulses with varying plasma configurations. In this approach, a 1-D Finite Difference Time Domain (FDTD) model was constructed to simulate the interaction of terahertz radiation with a plasma medium. In order to incorporate the plasma properties into the simulation, a Z-transformation was applied. This model is capable of simulating the following properties of plasmas including electron density, collision frequency, and the interaction length of the plasma medium. The simulated model was characterized using terahertz time-domain spectroscopy. The effects of …
Development Of Embedded Atom Method Interatomic Potentials For Ge-Sn-Si Ternary And Constituent Binary Alloys For Modeling Material Crystallization, Sudip Acharya
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Group IV elements based nanoelectronics devices (mainly Si and Ge based devices) have been developed and improved over a long period of time and are the most influencing materials of semiconductor electronics, but due to their indirect bandgap their use in optoelectronics is limited. Alternatively, new Group IV alloys comprised of Ge, Si, and Sn semiconductor materials have emerged as attractive options for various electronic and optoelectronic applications. The binary and ternary alloys provide strain and energy bandgap engineering by controlling element content, a route for realizing direct-transition semiconductors, improvement in interface and defect properties, and a reduction of the …
Characterization Of A Novel Terahertz Chemical Sensor, Daniel J. Tyree
Characterization Of A Novel Terahertz Chemical Sensor, Daniel J. Tyree
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A recently constructed novel analytical tabletop terahertz (THz) chemical sensor capable of detecting a wide range of gases with high sensitivity and specificity was characterized to assess its performance over a range of operational parameters. The sensor was designed with an objective of quantifying composition of exhaled human breath, where target concentrations span part per trillion (ppt) to part per billion (ppb) level of dilutions. The sensor utilizes terahertz rotational spectroscopy of sampled gases for quantification of dilutions. The sensor occupies a volume of ~ 2 ft3 and incorporates a coiled absorption cell, thermal desorption tubes, and all necessary electronic …
Evolution Of Electron Properties After Nanosecond Repetitively Pulsed Discharges In Air Measured By Thomson Scattering, Chase S. Murray
Evolution Of Electron Properties After Nanosecond Repetitively Pulsed Discharges In Air Measured By Thomson Scattering, Chase S. Murray
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This work was an investigation of nanosecond repetitively pulsed discharges in air by measuring the evolution of electron density and electron temperature between pulses using Thomson scattering of laser light. Bursts of repetitive pulses within several microseconds after the initial pulse were found to exhibit a coupling effect and create an even higher electron density than the initial pulse. The wide range of temperatures and densities of the electrons existing between pulses allow an opportunity to explore both the collective and non-collective regimes of Thomson scattering. By measuring electron density and temperature at a variety of times, an accurate description …
One-Dimensional Kinetic Particle-In-Cell Simulations Of Various Plasma Distributions, Richard N. Vanderburgh
One-Dimensional Kinetic Particle-In-Cell Simulations Of Various Plasma Distributions, Richard N. Vanderburgh
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A one-dimensional kinetic particle-in-cell (PIC) MATLAB simulation was created to demonstrate the time-evolution of various plasma distributions. Building on previous plasma PIC programs written in FORTRAN and Python, this work recreates the computational and diagnostic tools of these packages in a more user- and educational-friendly development environment. Plasma quantities such as plasma frequency and species charge-mass ratios are arbitrarily defined. A one-dimensional spatial environment is defined by total length and number and size of spatial grid points. In the first time-step, charged particles are given initial positions and velocities on a spatial grid. After initialization, the program solves for the …
The Magnetocaloric Effect & Performance Of Magnetocaloric Materials In A 1d Active Magnetic Regenerator Simulation, Daniel Nicholas Bayer
The Magnetocaloric Effect & Performance Of Magnetocaloric Materials In A 1d Active Magnetic Regenerator Simulation, Daniel Nicholas Bayer
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Active magnetic regenerators (AMRs) operate according to the magnetothermal phenomenon known as the magnetocaloric effect (MCE), and are at the forefront of magnetic cooling technology. AMR simulations have been shown to be useful tools in predicting the performance of different magnetocaloric materials (MCMs) without the need to develop a physical prototype. In a search to determine the set of operational parameters which would maximize MCM performance, a 1D simulation of an AMR device has been developed in Matlab. Gadolinium, the most well-documented MCM, is used as a benchmark material to study the effects of varying certain operational parameters such as …
The Influence Of A Surface On Hysteresis Loops For Single-Domain Ferromagnetic Nanoparticles, Saad Alsari
The Influence Of A Surface On Hysteresis Loops For Single-Domain Ferromagnetic Nanoparticles, Saad Alsari
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The influence of surface effects on a hysteresis loop for single domain, ferromagnetic nanoparticles was examined. Theoretical equations were derived to describe the magnetic behavior of the domains and a MATLAB program was used to solve them. M-H curves were calculated for the case when a magnetic field is applied in the favorable magnetization direction (easy axis). In contrast, the calculations show there were no hysteresis loops when the magnetic field was applied perpendicular to the easy axis. Our studies showed how parameters of the surface such as a associated with saturation magnetization near the surface of nanoparticles and Ks …
Establishing A Quality Assurance Routine For Digital Imaging, Sulaiman Rana Al
Establishing A Quality Assurance Routine For Digital Imaging, Sulaiman Rana Al
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In the clinical medical physics field, Quality Assurance (QA) is a fundamental topic to insure patient safety and effective treatment. In recent years, the imaging hardware for diagnostic x-rays has been shifting to fully digital detectors. However, the quality assurance tests for such detectors in the clinical setting is still under development. In the Medical Imaging Department of Kettering Hospital (Kettering, OH), the currently accepted method of performing QA on detectors is to use an extensive set of tests suggested by the manufacturer. This set of tests requires about 90 minutes, which is too long for daily use. The goal …
Determination Of Dose Effects When Including Attenuation Of The Treatment Table Into Treatment Planning Computer Modeling, Abdullah Alshamrany
Determination Of Dose Effects When Including Attenuation Of The Treatment Table Into Treatment Planning Computer Modeling, Abdullah Alshamrany
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During radiation treatment, the patient commonly lies on a horizontal treatment table called a couch. The material used for the couch is chosen during the manufacturing process so as to minimize the effect of the couch on dose delivery, but it still has an effect. In addition to couch attenuation on the beam, the modern approach of using multiple beam angles for dose delivery makes treatment planning in the presence of the couch more challenging. However, the effect of the couch is not always considered when creating treatment plans, generally due to treatment planning software limitations. In this evaluation, the …
Electromagnetic Properties Of Fractal Antennas, Jordan Jeffrey Ewing
Electromagnetic Properties Of Fractal Antennas, Jordan Jeffrey Ewing
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Finite element method analysis is used to conduct electromagnetic simulations to characterize fractal antennas. This work considers wire (1D) antennas such as the triadic Koch curve, zig zag, and quadratic Koch curve of varying heights, iterations, and cross-sectional areas. Carpet (2D) antennas, including the Sierpinksi carpet, of varying heights, iterations, and deterministic and stochastic iterations are analyzed. The antenna shapes were generated in MATLAB and then modeled with finite element analysis using COMSOL Multiphysics®. The focus of this study is to determine what role various fractal patterns and iterations have on the S11 return loss and far field radiation patterns. …
A Parallel Spectral Method Approach To Model Plasma Instabilities, Kevin S. Scheiman
A Parallel Spectral Method Approach To Model Plasma Instabilities, Kevin S. Scheiman
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The study of solar-terrestrial plasma is concerned with processes in magnetospheric, ionospheric, and cosmic-ray physics involving different particle species and even particles of different energy within a single species. Instabilities in space plasmas and the earth's atmosphere are driven by a multitude of free energy sources such as velocity shear, gravity, temperature anisotropy, electron, and, ion beams and currents. Microinstabilities such as Rayleigh-Taylor and Kelvin-Helmholtz instabilities are important for the understanding of plasma dynamics in presence of magnetic field and velocity shear. Modeling these turbulences is a computationally demanding processes; requiring large memory and suffer from excessively long runtimes. Previous …
Molecular Dynamics Study Of Hydrogen Trapping And Helium Clustering In Tungsten, Ashok Gurung
Molecular Dynamics Study Of Hydrogen Trapping And Helium Clustering In Tungsten, Ashok Gurung
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The field of plasma confinement and path toward achieving thermonuclear fusion started with experimental devices like tokamak and has evolved into other more complex variants of magnetic plasma confinement such as stellarator and spherical-tokamaks. As the plasma confinement machines advance towards higher temperature and plasma density (thermonuclear fusion conditions) the role and nature of plasma-wall interaction such as possible edge plasma regimes, particle recycling at the walls and its consequence for erosion, migration and re-deposition of wall material and impurity generation, transport and radiation as well as issues of particle exhaust continues to be a dominant limiting factor due to …
Detection And Analysis Of Polyurethane Biodegradation Due To Cryptococcus Laurentii, Tyler Jacob Zicht
Detection And Analysis Of Polyurethane Biodegradation Due To Cryptococcus Laurentii, Tyler Jacob Zicht
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Current United States aircraft are equipped with a multitude of protective coatings on the interior and exterior of the vehicle, ultimately enhancing their ability to ensure a safe and effective mission. Aircraft, over the course of their lifetime, will experience impact, corrosion, weathering, and microbial damage to its defensive structures, rendering it vulnerable to attacks. Damaged coatings are then repaired on the aircraft once detected in inspection or replaced in accordance to the lifecycle of the material on the aircraft. However potentially harmful threats such as bacteria are not considered by the Air Force to be dangerous. Therefore, the purpose …
Adaptive Optics System Baseline Modeling For A Usaf Quad Axis Telescope, Nathaniel R. Morris
Adaptive Optics System Baseline Modeling For A Usaf Quad Axis Telescope, Nathaniel R. Morris
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Atmospheric turbulence has afflicted accurate observations of celestial bodies since man first gazed upon the stars. In this past century, the technology of adaptive optics was invented to help compensate for the optical distortions that atmospheric turbulence causes. As part of that technology, artificial guide stars, wave front sensors, deformable mirrors, and other optical components were developed to correct these wave aberrations. The purpose of this study focuses on the modeling and configuration of an adaptive optics system that is appropriate for the John Bryan Observatory Quad Axis Telescope System (JBO-Q), which is funded by the United States Air Force. …
Determination Of The Shape Of A Flattening Filter Free (Fff) Radiation Beam When Modified By A Physical Wedge, Kalel Alsaeed
Determination Of The Shape Of A Flattening Filter Free (Fff) Radiation Beam When Modified By A Physical Wedge, Kalel Alsaeed
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The determination of a flattening filter free (FFF) beam profile when the collimator is intentionally modified to incorporate a physical wedge. Specifically, radiation beam profiles change shape when a metallic wedge is placed in the path of the beam. Examination of this unknown is necessary to ascertain whether a physical wedge is clinically beneficial for applications involving FFF beams. The aim of this study is to determine if the radiation profile of a flattening filter free beam having a physical wedge is comparable to a beam with a flattening filter, with the same wedge inserted. This research involves measurement of …
Extraordinary Optical Transmission In Aligned Carbon Nanotube Devices At Terahertz Frequencies., Shaikhah F. Almousa
Extraordinary Optical Transmission In Aligned Carbon Nanotube Devices At Terahertz Frequencies., Shaikhah F. Almousa
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In the phenomenon known as extraordinary optical transmission (EOT), a narrow band of selected frequencies are transmitted when incident on an array of subwavelength periodic apertures where the resonant frequency is determined by the geometry of the array of apertures and optical properties of the metal-dielectric interface. This takes place due to the excitation of surface plasmon polaritons (SPPs) at the metal and dielectric interface. Using the COMSOL Multiphysics software RF Module, a unit cell of a carbon nanotube (CNT) based EOT device is modeled in order to verify theoretical calculations of the resonant frequency using S-parameter calculations. The simulation …
Multiscale Modeling Of Carbon Nanotube Synthesis In A Catalytic Chemical Vapor Deposition Reactor, Jonathan Troville
Multiscale Modeling Of Carbon Nanotube Synthesis In A Catalytic Chemical Vapor Deposition Reactor, Jonathan Troville
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The bottom-up analysis of Carbon Nanotube synthesis is not well understood. Specifically, the question as to how carbon adsorbs to a substrate inclusive of a supported catalyst may lead to the energetically favorable structure of a hexagonal close- packed structure along the wall, or walls, of the tube. A first time simulation using COMSOL Multiphysics has been generated in order to capture the gas-phase mech- anism which leads to carbon production. It is thought that the carbon adsorbs and the walls are formed from the bottom up and the inside out for multi-wall CNTs. The studies involved accurately setting up …
Towards A Prediction Of Landscape Evolution From Chemical Weathering And Soil Production, Eric Alan Jackson
Towards A Prediction Of Landscape Evolution From Chemical Weathering And Soil Production, Eric Alan Jackson
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The time evolution of a periodic landscape under the influence of chemical weathering and physical erosion is computed. The model used incorporates weathering and soil production as a flux limited reaction controlled by groundwater flow. Scaling of the flow rate is obtained from a percolation theoretic treatment. The erosion of the soil material produced by this process is modeled by the diffusion of elevation, as consistent with downslope soil transport proportional to the tangent of the angle of the topography, and application of the equation of continuity to surface soil transport. Three initial topographies are examined over a periods of …
Thermoelectrical Properties Of Covetics, S. M. Sarif Rana
Thermoelectrical Properties Of Covetics, S. M. Sarif Rana
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Covetics are hybrid materials fabricated by fusing carbon with metals in an induction furnace. There is an indication that covetics have better thermal and electrical proper-ties in comparison with pure metals. The main goal of this research is to study thermal transport in covetics measured by specific absorption rate using calorimetry. In addition, temperature distribution has been measured along the both metal and covetic wires carrying currents of 5 A and 10 A, respectively. The first set of copper covetic (Cu cov) samples with nominal content of 36 at% carbon were prepared by Third Millennium Materials Company (TMMC) in the …
Terahertz Molecular Spectroscopy As A Tool For Analytical Probing Of Cellular Metabolism, Mitchell Cameron Paul
Terahertz Molecular Spectroscopy As A Tool For Analytical Probing Of Cellular Metabolism, Mitchell Cameron Paul
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Terahertz spectroscopy has found use as an analytical tool in determining chemical composition of exhaled human breath. This thesis demonstrates a novel application of this technology - analytical sensing of gaseous metabolic products of several types of human cell cultures. An innovative experimental system was developed for probing cellular metabolism using terahertz [THz] rotational spectroscopy. Gaseous emissions of cell cultures were analyzed and compared between several cell types. Cancerous and healthy lung cells as well as cancerous liver cells were studied. This technique carries a lot of promise as a noninvasive method of distinguishing between cell types and identifying cell …
Experimental Investigation Of A Parametric Excitation Of Whistler Waves, Nathan E. Zechar
Experimental Investigation Of A Parametric Excitation Of Whistler Waves, Nathan E. Zechar
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Previous theoretical work has shown that a parametric interaction between electrostatic lower oblique resonance (LOR) and ion acoustic waves (IAW) can produce electromagnetic whistler waves in a cold magnetized plasma. It was also demonstrated theoretically that this interaction can more efficiently generate electromagnetic whistler waves than by direct excitation using a conventional loop antenna. For the purpose of experimentally validating the above result, an experimental facility was designed and constructed utilizing a vacuum chamber, electromagnets, and a helicon plasma source array capable of producing a volume of plasma with high density and spatial uniformity. Additionally, positioning equipment and plasma diagnostics …
Terahertz Molecular Spectroscopy As A Tool For Analytical Probing Of Cellular Metabolism, Mitchell Cameron Paul
Terahertz Molecular Spectroscopy As A Tool For Analytical Probing Of Cellular Metabolism, Mitchell Cameron Paul
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Terahertz spectroscopy has found use as an analytical tool in determining chemical composition of exhaled human breath. This thesis demonstrates a novel application of this technology - analytical sensing of gaseous metabolic products of several types of human cell cultures. An innovative experimental system was developed for probing cellular metabolism using terahertz [THz] rotational spectroscopy. Gaseous emissions of cell cultures were analyzed and compared between several cell types. Cancerous and healthy lung cells as well as cancerous liver cells were studied. This technique carries a lot of promise as a noninvasive method of distinguishing between cell types and identifying cell …
A Study Of Alkali-Resistant Materials For Use In Atomic Physics Based Systems, Aaron Thomas Fletcher
A Study Of Alkali-Resistant Materials For Use In Atomic Physics Based Systems, Aaron Thomas Fletcher
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Due to shortcomings in emerging alkali-based atomic physics based systems, a need to investigate alkali resistant materials has arisen. There is interest in alkali based systems such as atomic clocks and diode pumped alkali laser (DPAL) systems. In the case of atomic clocks and DPALs, alkali metal vapor, such as Rb, is the active part of the systems. The alkali vapor is confined in some manner of housing, but the transmission of electromagnetic radiation is required in the cells. This requires the incorporation of windows into the cell. The current window material, however, have been shown to degrade over time, …
Surface Effect Of Ferromagnetic Nanoparticles On Transition Between Single- And Multi-Domain Structure Or Between Single-Domain Structure And Superparamagnetic Phase, Hind Adawi
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Surface effects on critical dimensions of ferromagnetic nanoparticles were studied. Algebraic equations were derived and numerically solved for critical radius RC2 of ferromagnetic nanoparticles describing the transition between single- and multi-domain magnetic structure. Results were analyzed to illustrate the effect of surface parameters related to saturation magnetization a, exchange interaction ß, and anisotropy KS on the critical radius of nanoparticles with a core value of anisotropy KV. Available experimental data for MnBi, FePt, and CoPt or for Fe nanoparticles were used as examples of nanoparticles with high and low values of KV, respectively. Our studies clearly show that discrepancies existing …
Social Network Analysis And The Representation Of Female Students In Introductory Undergraduate Physics, Sarah Teresa Hierath
Social Network Analysis And The Representation Of Female Students In Introductory Undergraduate Physics, Sarah Teresa Hierath
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Physics Education Research has begun to focus on the learning habits, success, and connections of students in physics classrooms using Social Network Analysis (SNA). SNA is an important tool in studying classroom dynamics because it can be used to map the social structure of a classroom's interactions and to aid in understanding how students work and study together. This study presents network diagrams, statistics, centrality measures, and conceptual understanding correlations for 7 different sections of introductory physics. Centrality measures were determined from a first and last week survey in which students were asked to indicate their study partners within the …
Terahertz Spectroscopic Breath Analysis As A Viable Analytical Chemical Sensing Technique, Robert M. Schueler
Terahertz Spectroscopic Breath Analysis As A Viable Analytical Chemical Sensing Technique, Robert M. Schueler
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The ability to quantify trace chemicals in human breath enables the possibility of identifying breath biomarkers to aid in diagnosis. The vast majority of the studies in the analytical breath analysis rely on GC-MS techniques for quantification of the human breath composition1,2,3,4. THz spectroscopy of breath is rapid, sensitive, and highly specific molecular identification in complex mixtures containing 10-100 analytes with near `absolute' specificity. THz spectroscopic breath analyzers require chemical preconcentration. A newly developed custom preconcentrator was constructed and compared in its performance to a commercial system. Unlike the commercial counterpart, the new system does not require cryogenic liquids, is …