Physics Commons^™

Laser Filamentation - Beyond Self-Focusing And Plasma Defocusing, Khan Lim

Electronic Theses and Dissertations

Laser filamentation is a highly complex and dynamic nonlinear process that is sensitive to many physical parameters. The basic properties that define a filament consist of (i) a narrow, high intensity core that persists for distances much greater than the Rayleigh distance, (ii) a low density plasma channel existing within the filament core, and (iii) a supercontinuum generated over the course of filamentation. However, there remain many questions pertaining to how these basic properties are affected by changes in the conditions in which the filaments are formed; that is the premise of the work presented in this dissertation. To examine …

Distribution Of Laser Induced Heating In Multi-Component Chalcogenide Glass And Its Associated Effects, Laura Sisken

Electronic Theses and Dissertations

Chalcogenide glasses are well known to have good transparency into the infrared spectrum. These glasses though tend to have low thresholds as compared to oxide glasses for photo-induced changes and thermally-induced changes. Material modification such as photo-induced darkening, bleaching, refractive index change, densification or expansion, ablation of crystallization have been demonstrated, and are typically induced by a thermal furnace-based heat treatment, an optical source such as a laser, or a combination of photo-thermal interactions. Solely employing laser-based heating has an advantage over a furnace, since one has the potential to be able to spatially modify the materials properties with much …

Highly-Sensitive Stoichiometric Analysis Of Yag Ceramics Using Laser-Induced Breakdown Spectroscopy (Libs), Jahromi, Ali Kazemi

Electronic Theses and Dissertations

Transparent ceramics are an important class of optical materials with applications in high-strength windows, radiation detectors and high-power lasers. Despite the many successful developments of the past decades, their challenging fabrication still needs to be perfected to achieve a better consistency in optical quality. In particular, ternary phase materials such as Yttrium Aluminum Garnet (YAG, Y3Al5O12), a long standing high-power laser host, require a precise control of stoichiometry, often beyond the precision of current analytical techniques, in order to reduce scattering losses and the presence of deleterious point defects. This work explores the potential of Laser-Induced Breakdown Spectroscopy (LIBS) for …

Electronic Transport And Correlations In Single Magnetic Molecule Devices, Javier Romero

Electronic Theses and Dissertations

In this dissertation, we study the most important microscopic aspects that grant molecules such as Single Molecule Magnets (SMMs) their preferential spin direction. We do so by proposing and solving a model that includes correlations between electrons occupying atomic orbitals. In addition, we study the relation between the non-equilibrium electronic transport signatures in a SMM model weakly coupled to a three-terminal single electron transistor device, and the interference features of the SMM model in the presence of a magnetic field. Finally, we investigate the equilibrium transport features in a giant-spin model of a SMM in the Kondo regime. We study …

Creation And Application Of Routines For Determining Physical Properties Of Asteroids And Exoplanets From Low Signal-To-Noise Data Sets, Nathaniel Lust

Electronic Theses and Dissertations

Astronomy is a data heavy field driven by observations of remote sources reflecting or emitting light. These signals are transient in nature, which makes it very important to fully utilize every observation. This however is often difficult due to the faintness of these observations, often are only slightly above the level of observational noise. We present new or adapted methodologies for dealing with these low signal-to-noise scenarios, along with practical examples including determining exoplanet physical properties, periodicities in asteroids, and the rotational and orbital properties of the multiple asteroid system 2577 Litva.

Broad Bandwidth, All-Fiber, Thulium-Doped Photonic Crystal Fiber Amplifier For Potential Use In Scaling Ultrashort Pulse Peak Powers, Alex Sincore

Electronic Theses and Dissertations

Fiber based ultrashort pulse laser sources are desirable for many applications; however generating high peak powers in fiber lasers is primarily limited by the onset of nonlinear effects such as self-phase modulation, stimulated Raman scattering, and self-focusing. Increasing the fiber core diameter mitigates the onset of these nonlinear effects, but also allows unwanted higher-order transverse spatial modes to propagate. Both large core diameters and single-mode propagation can be simultaneously attained using photonic crystal fibers. Thulium-doped fiber lasers are attractive for high peak power ultrashort pulse systems. They offer a broad gain bandwidth, capable of amplifying sub-100 femtosecond pulses. The longer …

Three‐Dimensional Brain Mri For Dbs Patients Within Ultra‐Low Radiofrequency Power Limits, Subhendra N. Sarkar, Efstathios Papavassiliou, David Hackney, David Alsop, Ananth Madhuranthakam, Ludy Shih, Reed Busse, Susan Laruche, Rafeeque Bhadelia

Publications and Research

Background: For patients with deep brain stimulators (DBS), local absorbed radiofrequency (RF) power is unknown and is much higher than what the system estimates. We developed a comprehensive, highquality brain magnetic resonance imaging (MRI) protocol for DBS patients utilizing three-dimensional (3D) magnetic resonance sequences at very low RF power. Methods: Six patients with DBS were imaged (10 sessions) using a transmit/receive head coil at 1.5 Tesla with modified 3D sequences within ultra-low specific absorption rate (SAR) limits (0.1 W/kg) using T2, fast fluid-attenuated inversion recovery (FLAIR) and T1- weighted image contrast. Tissue signal and tissue contrast from the low-SAR images …

Techniques For Characterization Of Third Order Optical Nonlinearities, Manuel Ferdinandus

Electronic Theses and Dissertations

This dissertation describes the development of novel techniques for characterization of nonlinear properties of materials. The dissertation is divided into two parts, a background and theory section and a technique development section. In the background and theory section we explain the origins of the nonlinear optical response of materials across many different spatial and temporal scales. The mechanisms that we are most interested in are the electronic nuclear and reorientational responses, which occur on the range of sub-femtosecond to several picoseconds. The electronic mechanism is due to the electrons of a material experiencing a non-parabolic potential well due a strong …

Multimaterial Fibers And Tapers A Platform For Nonlinear Photonics And Nanotechnology, Soroush Shabahang

Electronic Theses and Dissertations

The development of optical sources and components suitable for the mid-infrared is crucial for applications in this spectral range to reach the maturity level of their counterparts in the visible and near-infrared spectral regimes. The recent commercialization of quantum cascade lasers is leading to further interest in this spectral range. Wideband mid-infrared coherent sources, such as supercontinuum generation, have yet to be fully developed. A mid-infrared supercontinuum source would allow for unique applications in spectroscopy and sensing. Over the last decade, it has been shown that high-index confinement in highly nonlinear fibers pumped with high-peak-power pulses is an excellent approach …

Bridging Physics And Biology Teaching Through Modeling, Anne-Marie Hoskinson, Brian A. Couch, Benjamin M. Zwickl, Kathleen A. Hinko, Marcos D. Caballero

School of Biological Sciences: Faculty Publications

As the frontiers of biology become increasingly interdisciplinary, the physics education community has engaged in ongoing efforts to make physics classes more relevant to life science majors. These efforts are complicated by the many apparent differences between these fields, including the types of systems that each studies, the behavior of those systems, the kinds of measurements that each makes, and the role of mathematics in each field. Nonetheless, physics and biology are both sciences that rely on observations and measurements to construct models of the natural world. In this article, we propose that efforts to bridge the teaching of these …

Is The Quantum State Real? An Extended Review Of Psi-Ontology Theorems, Matthew S. Leifer

Mathematics, Physics, and Computer Science Faculty Articles and Research

Towards the end of 2011, Pusey, Barrett and Rudolph derived a theorem that aimed to show that the quantum state must be ontic (a state of reality) in a broad class of realist approaches to quantum theory. This result attracted a lot of attention and controversy. The aim of this review article is to review the background to the Pusey–Barrett–Rudolph Theorem, to provide a clear presentation of the theorem itself, and to review related work that has appeared since the publication of the Pusey–Barrett–Rudolph paper. In particular, this review: Explains what it means for the quantum state to be ontic …

A Bayesian Approach To Compatibility, Improvement, And Pooling Of Quantum States, Matthew S. Leifer, Robert W. Spekkens

Mathematics, Physics, and Computer Science Faculty Articles and Research

In approaches to quantum theory in which the quantum state is regarded as a representation of knowledge, information, or belief, two agents can assign different states to the same quantum system. This raises two questions: when are such state assignments compatible? and how should the state assignments of different agents be reconciled? In this paper, we address these questions from the perspective of the recently developed conditional states formalism for quantum theory [1]. Specifically, we derive a compatibility criterion proposed by Brun, Finkelstein and Mermin from the requirement that, upon acquiring data, agents should update their states using a quantum …

From Quanta To Qualia: How A Paradigm Shift Turns Into Science. Philosophy Study Vol. 4, Deepak Chopra, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

Ever since the development of quantum mechanics in the first part of the 20th century, a new world view has emerged. Today, the physicalist objective assumption that objects exist independently of acts of observation has been challenged. The repercussions of this radical challenge to our common-sense perception of the world are far-reaching, although not yet generally realized. Here we argue that there is a complementary view to the way science which is being practiced, and that consciousness itself is primary and qualia form the foundation of experience. We outline the arguments of why the new science of qualia will tie …

“Spaghetti” Design For Gravitational Wave Superconducting Antenna, Armen Gulian, J Foreman, Vahan Nikoghosyan, Shmuel Nussinov, Louis Sica, Jeff Tollaksen

Mathematics, Physics, and Computer Science Faculty Articles and Research

A new concept for detectors of gravitational wave radiation is discussed. Estimates suggest that strain sensitivity essentially better than that of the existing devices can be achieved in the wide frequency range. Such sensitivity could be obtained with devices about one meter long. Suggested device consists of multi-billion bimetallic superconducting wires ("spaghettis") and requires cryogenic operational temperatures (~0.3K in the case considered).

Beam Energy Dependence Of Moments Of The Net-Charge Multiplicity Distributions In Au + Au Collisions At Rhic, L. Adamczyk, J. K. Adkins, G. Agakishiev, S. Bültmann, D. Plyku, Star Collaboration

Physics Faculty Publications

We report the first measurements of the moments-mean (M), variance (σ²), skewness (S), and kurtosis (κ)-of the net-charge multiplicity distributions at midrapidity in Au + Au collisions at seven energies, ranging from √ˢᶰᶰ = 7.7 to 200 GeV, as a part of the Beam Energy Scan program at RHIC. The moments are related to the thermodynamic susceptibilities of net charge, and are sensitive to the location of the QCD critical point. We compare the products of the moments, σ²/M, Sσ, and κσ², with the expectations from Poisson and negative binomial distributions (NBDs). The Sσ …

Dielectron Mass Spectra From Au Plus Au Collisions At √ˢᴺᴺ = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, S. Bültmann, D. Plyku, Star Collaboration

Physics Faculty Publications

We report the STAR measurements of dielectron (e⁺e^-) production at midrapidity ( |y_ee| < 1) in Au + Au collisions at √ˢᴺᴺ = 200 GeV. The measurements are evaluated in different invariant mass regions with a focus on 0.30-0.76 (ρ-like), 0.76-0.80 (ω-like), and 0.98-1.05 (ɸ-like) GeV/c². The spectrum in the ω-like and ɸ-like regions can be well described by the hadronic cocktail simulation. In the ρ-like region, however, the vacuum ρ spectral function cannot describe the shape of the dielectron excess. In this range, an enhancement of 1.77 ±0.11(stat) ± 0.24(syst) ± 0.33(cocktail) is determined with respect to the hadronic cocktail simulation that excludes the ρ meson. The excess yield in the ρ-like region increases with the number of collision participants faster than the ω …

Multipole And Field Uniformity Tailoring Of A 750 Mhz Rf Dipole, A. Castilla, Jean R. Delayen

Physics Faculty Publications

In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency …

Long-Range Propagation, Interaction, And Dissipation Of Small-Scale Gravity Waves In The Mesosphere And Lower Thermosphere, Christopher J. Heale

Doctoral Dissertations and Master's Theses

A 2-D nonlinear, compressible numerical model [Snively and Pasko, 2008] is used in conjunction with ray-theory to investigate the long-range propagation, dissipation and interaction of small-scale gravity waves in the Mesosphere and Lower Thermosphere (MLT) region. The research in this thesis is made up of three distinct studies which build upon each other. The first investigates the thermospheric dissipation of three gravity wave packets representing: (1) A quasi-monochromatic packet, (2) A monochromatic, steady state wave, and (3) A spectrally broad packet, as well as an initial condition specified packet. It is found that dissipation due to molecular viscosity and …

The Effect Of Electron-Hole Pairs In Semiconductor And Topological Insulator Nanostructures On Plasmon Resonances And Photon Polarizations., Hari Paudel

Electronic Theses and Dissertations

The generation of electron-hole pairs in materials has great importance. In direct bandgap semiconductor materials, the mechanism of radiative recombination of electron-hole pairs leads to the emission of photons, which is the basis of Light Emitting Diodes (LEDs). The excitation of electron-hole pairs by absorption of photons is the active process in photodiodes, solar cells, and other semiconductor photodetector devices. In optoelectronic devices such as optical switches which are based on transmission and reflection of the photons, electron-hole pairs excitation is a key for the device performance. Diodes and transistors are also great discoveries in electronics which rely on the …

Concern-Driven Integrated Toxicity Testing Strategies For Nanomaterials - Report Of The Nanosafety Cluster Working Group 10, Hugh Byrne, Agnes G. Oomen, Peter M.J. Bos, Teresa F. Fernandes, Kerstin Hund-Rinke, Diana Boraschi, Karin Aschberger, Stefania Gottardo, Frank Von Der Kammer, Dana Kühnel, Danail Hristozov, Antonio Marcomini, Lucia Migliore

Articles

Bringing together topic-related European Union-(EU)-funded projects, the so-called “NanoSafety Cluster” aims at identifying key areas for further research on risk assessment procedures for nanomaterials (NM). The outcome of NanoSafety Cluster Working Group 10, this commentary presents a vision for concern-driven integrated approaches for the (eco-)toxicological testing and assessment (IATA) of NM. Such approaches should start out by determining concerns, i.e. specific information needs for a given NM based on realistic exposure scenarios. Recognized concerns can be addressed in a set of tiers using standardized protocols for NM preparation and testing. Tier 1 includes determining physico-chemical properties, non-testing (e.g. structure …

Effect Of Substrate Choice And Tissue Type On Tissue Preparation For Spectral Histopathology By Raman Microspectroscopy, Hugh Byrne, Leanne M. Fullwood, Dave Griffiths, Katherine Ashton, Timothy Dawson, Robert W. Lea, Charles Davis, Franck Bonnier, Matthew J. Baker

Articles

Raman spectroscopy is a non-destructive, non-invasive, rapid and economical technique which has the potential to be an excellent method for the diagnosis of cancer and understanding disease progression through retrospective studies of archived tissue samples. Historically, biobanks are generally comprised of formalin fixed paraffin preserved tissue and as a result these specimens are often used in spectroscopic research. Tissue in this state has to be dewaxed prior to Raman analysis to reduce paraffin contributions in the spectra. However, although the procedures are derived from histopathological clinical practice, the efficacy of the dewaxing procedures that are currently employed is questionable. Ineffective …

Comparison Of Life Experiences Of Men And Women In The Sciences, Tori Nicole Quist

Honors Program Theses

A lack of sense of belonging and stereotype threat have been shown to contribute to women leaving the sciences (Seymour, 1997; Beasley & Fischer, 2012; Deemer et al., 2013). Contributing to this is the fact that most women find affirmation externally (through friends, family and professors) for their life decisions (Seymour, 1997; Zeldin, 2000). A set of comparative studies in 2000 and 2008 were done examining factors affecting women’s and men’s choices of majors and careers (Zeldin, 2000 and Zeldin, 2008). These studies concluded that men relied on achievements in science as the source of their career decisions to enter …

Optical And Hybrid Imaging And Processing For Big Data Problems, Khan Iftekharuddin, Abdul A. S. Awwal, S. Susan Young, Ghaleb M. Abdulla

Electrical & Computer Engineering Faculty Publications

(First paragraph) The scientific community has been dealing with big data for a long time. Due to advancement in sensing, networking, and storage technology, other domains such as business, health, and social media followed. Data are considered the gold of the 21st century and are being collected, stored, and analyzed at a rapid pace. The amount of data being collected creates a compelling case for investing in hardware and software research to support generating even more data from new sensors and with better quality. It also creates a compelling case for investing in research and development of new hardware and …

Next Discoveries In Neutrino Mixing: Electron Neutrino Appearance, Hongyue Duyang

Theses and Dissertations

The discovery of neutrino oscillation is a clear evidence of new physics beyond the Standard Model. Measurements of electron neutrino ($\nu_e$) and electron anti-neutrino $\bar{\nu}_{e}$ appearances are the most important channels to complete the neutrino mixing matrix. In a $ \nu_{e} $/$\bar{\nu}_{e}$ appearance experiment, a near detector (ND) is used to constrain the neutrino flux and measure the backgrounds to the signal. Backgrounds to the $ \nu_{e} $ appearance comes from Neutral Current Muon Neutrino Interactions ($\nu_{\mu}$-NC), Charged Current Muon Neutrino Interactions ($\nu_{\mu}$-CC), beam $ \nu_{e} $ events and outside backgrounds. The background components are then extrapolated to the far …

Conformal Gravity Holography In Four Dimensions, Daniel Grumiller, Maria Irakleidou, Iva Lovrekovic,, Robert Mcnees

Physics: Faculty Publications and Other Works

We formulate four-dimensional conformal gravity with (anti–)de Sitter boundary conditions that are weaker than Starobinsky boundary conditions, allowing for an asymptotically subleading Rindler term concurrent with a recent model for gravity at large distances. We prove the consistency of the variational principle and derive the holographic response functions. One of them is the conformal gravity version of the Brown–York stress tensor, the other is a “partially massless response”. The on shell action and response functions are finite and do not require holographic renormalization. Finally, we discuss phenomenologically interesting examples, including the most general spherically symmetric solutions and rotating black hole …

Diagnostics Of An O2–He Rf Atmospheric Plasma Discharge By Spectral Emission, Vladimir Milosavljevic, Mick Donegan, Patrick J. Cullen, Denis Dowling

Articles

In this paper optical emission spectroscopy (OES) is used as a Diagnostic technique for the measurement of atomic and molecular spectral emissions generated using a helium rf industrial atmospheric plasma jet system. The OES of neutral atomic spectral lines and molecular bands are investigated over a range of plasma process parameters.
/="/">Wavelength resolve optical emission profiles suggest that the emission of helium’s spectral lines shows that the high energy electrons have a larger influence than helium metastables on the overall spectral emission. Furthermore, the experimental data indicates that the use of high helium flow rates, in any confined open …

Fluctuation-Dissipation Theorem In Isolated Quantum Systems Out Of Equilibrium, Ehsan Khatami, Guido Pupillo, Mark Srednicki, Marcos Rigol

Faculty Publications

We study the validity of the fluctuation-dissipation theorem for an isolated quantum system of harmonically trapped dipolar molecules taken out of equilibrium by means of a quench, a sudden change in the Hamiltonian parameters. We find that the integrability of the system plays a crucial role in the validity of the fluctuation-dissipation theorem. Namely, the system thermalizes according to the eigenstate thermalization hypothesis and the theorem holds if the system is nonintegrable after the quench. However, it fails if the system is integrable, unless the initial state is an eigenstate of a nonintegrable Hamiltonian, in which case the system still …

Comparison Of Computer-Based And Optical Face Recognition Paradigms, Abdulaziz A. Alorf

Dissertations, Master's Theses and Master's Reports - Open

The main objectives of this thesis are to validate an improved principal components analysis (IPCA) algorithm on images; designing and simulating a digital model for image compression, face recognition and image detection by using a principal components analysis (PCA) algorithm and the IPCA algorithm; designing and simulating an optical model for face recognition and object detection by using the joint transform correlator (JTC); establishing detection and recognition thresholds for each model; comparing between the performance of the PCA algorithm and the performance of the IPCA algorithm in compression, recognition and, detection; and comparing between the performance of the digital model …

Integration Of Instrumentation And Processing Software Of A Laser Speckle Contrast Imaging System, Jacob James Carrick

Dissertations, Master's Theses and Master's Reports - Open

Laser speckle contrast imaging (LSCI) has the potential to be a powerful tool in medicine, but more research in the field is required so it can be used properly. To help in the progression of Michigan Tech's research in the field, a graphical user interface (GUI) was designed in Matlab to control the instrumentation of the experiments as well as process the raw speckle images into contrast images while they are being acquired. The design of the system was successful and is currently being used by Michigan Tech's Biomedical Engineering department. This thesis describes the development of the LSCI GUI …

A Theoretical Study Of Interaction Of Nanoparticles With Biomolecule, Chunhui Liu

Dissertations, Master's Theses and Master's Reports - Open

Many types of materials at nanoscale are currently being used in everyday life. The production and use of such products based on engineered nanomaterials have raised concerns of the possible risks and hazards associated with these nanomaterials. In order to evaluate and gain a better understanding of their effects on living organisms, we have performed first-principles quantum mechanical calculations and molecular dynamics simulations. Specifically, we will investigate the interaction of nanomaterials including semiconducting quantum dots and metallic nanoparticles with various biological molecules, such as dopamine, DNA nucleobases and lipid membranes.

Firstly, interactions of semiconducting CdSe/CdS quantum dots (QDs) with the …