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Articles 1  30 of 152
FullText Articles in Physics
Mathematical And Physical Aspects Of Complex Symmetric Operators, Stephan Ramon Garcia, Emil Prodan, Mihai Putinar
Mathematical And Physical Aspects Of Complex Symmetric Operators, Stephan Ramon Garcia, Emil Prodan, Mihai Putinar
Pomona Faculty Publications and Research
Recent advances in the theory of complex symmetric operators are presented and related to current studies in nonhermitian quantum mechanics. The main themes of the survey are: the structure of complex symmetric operators, Cselfadjoint extensions of Csymmetric unbounded operators, resolvent estimates, reality of spectrum, bases of Corthonormal vectors, and conjugatelinear symmetric operators. The main results are complemented by a variety of natural examples arising in field theory, quantum physics, and complex variables.
Entropy Driven Crystal Formation On Highly Strained Substrates, John R. Savage, Stefan F. Hopp, Rajesh Ganapathy, Sharon J. Gerbode, Andreas Heuer, Itai Cohen
Entropy Driven Crystal Formation On Highly Strained Substrates, John R. Savage, Stefan F. Hopp, Rajesh Ganapathy, Sharon J. Gerbode, Andreas Heuer, Itai Cohen
All HMC Faculty Publications and Research
In heteroepitaxy, lattice mismatch between the deposited material and the underlying surface strongly affects nucleation and growth processes. The effect of mismatch is well studied in atoms with growth kinetics typically dominated by bond formation with interaction lengths on the order of one lattice spacing. In contrast, less is understood about how mismatch affects crystallization of larger particles, such as globular proteins and nanoparticles, where interparticle interaction energies are often comparable to thermal fluctuations and are short ranged, extending only a fraction of the particle size. Here, using colloidal experiments and simulations, we find particles with shortrange attractive interactions form ...
3d Imaging And Mechanical Modeling Of Helical Buckling In Medicago Truncatula Plant Roots, Jesse L. Silverberg, Roslyn D. Noar, Michael S. Packer, Maria J. Harrison, Christopher L. Henley, Itai Cohen, Sharon J. Gerbode
3d Imaging And Mechanical Modeling Of Helical Buckling In Medicago Truncatula Plant Roots, Jesse L. Silverberg, Roslyn D. Noar, Michael S. Packer, Maria J. Harrison, Christopher L. Henley, Itai Cohen, Sharon J. Gerbode
All HMC Faculty Publications and Research
We study the primary root growth of wildtype Medicago truncatula plants in heterogeneous environments using 3D timelapse imaging. The growth medium is a transparent hydrogel consisting of a stiff lower layer and a compliant upper layer. We find that the roots deform into a helical shape just above the gel layer interface before penetrating into the lower layer. This geometry is interpreted as a combination of growthinduced mechanical buckling modulated by the growth medium and a simultaneous twisting near the root tip. We study the helical morphology as the modulus of the upper gel layer is varied and demonstrate that ...
Black Hole Thermalization, D0 Brane Dynamics, And Emergent Spacetime, Paul L. Riggins '12, Vatche Sahakian
Black Hole Thermalization, D0 Brane Dynamics, And Emergent Spacetime, Paul L. Riggins '12, Vatche Sahakian
All HMC Faculty Publications and Research
When matter falls past the horizon of a large black hole, the expectation from string theory is that the configuration thermalizes and the information in the probe is rather quickly scrambled away. The traditional view of a classical unique spacetime near a black hole horizon conflicts with this picture. The question then arises as to what spacetime does the probe actually see as it crosses a horizon, and how does the background geometry imprint its signature onto the thermal properties of the probe. In this work, we explore these questions through an extensive series of numerical simulations of D0 branes ...
How The Cucumber Tendril Coils And Overwinds, Sharon J. Gerbode, Joshua R. Puzey, Andrew G. Mccormick, L. Mahadevan
How The Cucumber Tendril Coils And Overwinds, Sharon J. Gerbode, Joshua R. Puzey, Andrew G. Mccormick, L. Mahadevan
All HMC Faculty Publications and Research
The helical coiling of plant tendrils has fascinated scientists for centuries, yet the underlying mechanism remains elusive. Moreover, despite Darwin’s widely accepted interpretation of coiled tendrils as soft springs, their mechanical behavior remains unknown. Our experiments on cucumber tendrils demonstrate that tendril coiling occurs via asymmetric contraction of an internal fiber ribbon of specialized cells. Under tension, both extracted fiber ribbons and old tendrils exhibit twistless overwinding rather than unwinding, with an initially soft response followed by strong strainstiffening at large extensions. We explain this behavior using physical models of prestrained rubber strips, geometric arguments, and mathematical models of ...
Evolution Of SpurLength Diversity In Aquilegia Petals Is Achieved Solely Through CellShape Anisotropy, Joshua R. Puzey, Sharon J. Gerbode, Scott A. Hodges, Elena M. Kramer, L. Mahadevan
Evolution Of SpurLength Diversity In Aquilegia Petals Is Achieved Solely Through CellShape Anisotropy, Joshua R. Puzey, Sharon J. Gerbode, Scott A. Hodges, Elena M. Kramer, L. Mahadevan
All HMC Faculty Publications and Research
The role of petal spurs and specialized pollinator interactions has been studied since Darwin. Aquilegia petal spurs exhibit striking size and shape diversity, correlated with specialized pollinators ranging from bees to hawkmoths in a textbook example of adaptive radiation. Despite the evolutionary significance of spur length, remarkably little is known about Aquilegia spur morphogenesis and its evolution. Using experimental measurements, both at tissue and cellular levels, combined with numerical modelling, we have investigated the relative roles of cell divisions and cell shape in determining the morphology of the Aquilegia petal spur. Contrary to decadesold hypotheses implicating a discrete meristematic zone ...
Coalitions And Cliques In The School Choice Problem, Sinan Aksoy, Alexander Adam Azzam, Chaya Coppersmith, Julie Glass, Gizem Karaali, Xueying Zhao, Xinjing Zhu
Coalitions And Cliques In The School Choice Problem, Sinan Aksoy, Alexander Adam Azzam, Chaya Coppersmith, Julie Glass, Gizem Karaali, Xueying Zhao, Xinjing Zhu
Pomona Faculty Publications and Research
The school choice mechanism design problem focuses on assignment mechanisms matching students to public schools in a given school district. The wellknown Gale Shapley Student Optimal Stable Matching Mechanism (SOSM) is the most efficient stable mechanism proposed so far as a solution to this problem. However its inefficiency is welldocumented, and recently the Efficiency Adjusted Deferred Acceptance Mechanism (EADAM) was proposed as a remedy for this weakness. In this note we describe two related adjustments to SOSM with the intention to address the same inefficiency issue. In one we create possibly artificial coalitions among students where some students modify their ...
Evidence Of The Harmonic Faraday Instability In Ultrasonic Atomization Experiments With A Deep, Inviscid Fluid, Andrew P. Higginbotham '09, Aaron Guillen '11, Nathan C. Jones '10, Thomas D. Donnelly, Andrew J. Bernoff
Evidence Of The Harmonic Faraday Instability In Ultrasonic Atomization Experiments With A Deep, Inviscid Fluid, Andrew P. Higginbotham '09, Aaron Guillen '11, Nathan C. Jones '10, Thomas D. Donnelly, Andrew J. Bernoff
All HMC Faculty Publications and Research
A popular method for generating micronsized aerosols is to submerge ultrasonic (ω~MHz) piezoelectric oscillators in a water bath. The submerged oscillator atomizes the fluid, creating droplets with radii proportional to the wavelength of the standing wave at the fluid surface. Classical theory for the Faraday instability predicts a parametric instability driving a capillary wave at the subharmonic (ω/2) frequency. For many applications it is desirable to reduce the size of the droplets; however, using higher frequency oscillators becomes impractical beyond a few MHz. Observations are presented that demonstrate that smaller droplets may also be created by increasing the ...
Effect Of Substrate Composition And Alignment On Corneal Cell Phenotype, Donna Phu '09, Lindsay S. Wray '08, Robert V. Warren '10, Richard C. Haskell, Elizabeth J. Orwin
Effect Of Substrate Composition And Alignment On Corneal Cell Phenotype, Donna Phu '09, Lindsay S. Wray '08, Robert V. Warren '10, Richard C. Haskell, Elizabeth J. Orwin
All HMC Faculty Publications and Research
Corneal blindness is a significant problem treated primarily by corneal transplants. Donor tissue supply is low, creating a growing need for an alternative. A tissueengineered cornea made from patientderived cells and biopolymer scaffold materials would be widely accessible to all patients and would alleviate the need for donor sources. Previous work in this lab led to a method for electrospinning type I collagen scaffolds for culturing corneal fibroblasts ex vivo that mimics the microenvironment in the native cornea. This electrospun scaffold is composed of smalldiameter, aligned collagen fibers. In this study, we investigate the effect of scaffold nanostructure and composition ...
Dislocations And Vacancies In TwoDimensional Mixed Crystals Of Spheres And Dimers, Sharon J. Gerbode, Desmond C. Ong, Chekesha M. Liddell, Itai Cohen
Dislocations And Vacancies In TwoDimensional Mixed Crystals Of Spheres And Dimers, Sharon J. Gerbode, Desmond C. Ong, Chekesha M. Liddell, Itai Cohen
All HMC Faculty Publications and Research
In colloidal crystals of spheres, dislocation motion is unrestricted. On the other hand, recent studies of relaxation in crystals of colloidal dimer particles have demonstrated that the dislocation dynamics in such crystals are reminiscent of glassy systems. The observed glassy dynamics arise as a result of dislocation cages formed by certain dimer orientations. In the current study, we use experiments and simulations to investigate the transition that arises when a pure sphere crystal is doped with an increasing concentration of dimers. Specifically, we focus on both dislocation caging and vacancy motion. Interestingly, we find that any nonzero fraction of dimers ...
Glassy Dislocation Dynamics In 2d Colloidal Dimer Crystals, Sharon J. Gerbode, Ugmang Agarwal, Desmond C. Ong, Chekesha M. Liddell, Fernando Escobedo, Itai Cohen
Glassy Dislocation Dynamics In 2d Colloidal Dimer Crystals, Sharon J. Gerbode, Ugmang Agarwal, Desmond C. Ong, Chekesha M. Liddell, Fernando Escobedo, Itai Cohen
All HMC Faculty Publications and Research
Although glassy relaxation is typically associated with disorder, here we report on a new type of glassy dynamics relating to dislocations within 2D crystals of colloidal dimers. Previous studies have demonstrated that dislocation motion in dimer crystals is restricted by certain particle orientations. Here, we drag an optically trapped particle through such dimer crystals, creating dislocations. We find a twostage relaxation response where initially dislocations glide until encountering particles that cage their motion. Subsequent relaxation occurs logarithmically slowly through a second process where dislocations hop between caged configurations. Finally, in simulations of sheared dimer crystals, the dislocation mean squared displacement ...
Kinematic Evidence For Superfast Locomotory Muscle In Two Species Of Teneriffiid Mites, Grace C. Wu, Jonathan C. Wright, Dwight L. Whitaker, Anna N. Ahn
Kinematic Evidence For Superfast Locomotory Muscle In Two Species Of Teneriffiid Mites, Grace C. Wu, Jonathan C. Wright, Dwight L. Whitaker, Anna N. Ahn
All HMC Faculty Publications and Research
Locomotory muscles typically operate over a narrow range of contraction frequencies, characterized by the predominant fiber types and functional roles. The highest documented frequencies in the synchronous soundproducing muscles of insects (550 Hz) and toadfish (200 Hz) far exceed the contraction frequencies observed in weightbearing locomotory muscles, which have maximum documented frequencies below 1530 Hz. Laws of scaling, however, predict that smaller arthropods may employ stride frequencies exceeding this range. In this study we measured running speed and stride frequency in two undescribed species of teneriffiid mites from the coastal sage scrub of southern California. Relative speeds of both species ...
From Surface Operators To NonAbelian Volume Operators In Puff Field Theory, Vatche Sahakian
From Surface Operators To NonAbelian Volume Operators In Puff Field Theory, Vatche Sahakian
All HMC Faculty Publications and Research
Puff field theory (PFT) is a low energy decoupling regime of string theory that still retains the nonlocal attributes of the parent theory—while preserving isotropy for its nonlocal degrees of freedom. It realizes an extended holographic dictionary at strong coupling and dynamical nonlocal states akin to defects or the surface operators of local gauge theories. In this work, we probe the nonlocal features of PFT using D3 branes. We find supersymmetric configurations that end on defects endowed with nonAbelian degrees of freedom. These are 2+1 dimensional defects in the 3+1 dimensional PFT that may be viewed as ...
Kinematic Evidence For Superfast Locomotory Muscle In Two Species Of Teneriffiid Mites, Grace C. Wu, Jonathan C. Wright, Dwight L. Whitaker, Anna N. Ahn
Kinematic Evidence For Superfast Locomotory Muscle In Two Species Of Teneriffiid Mites, Grace C. Wu, Jonathan C. Wright, Dwight L. Whitaker, Anna N. Ahn
Pomona Faculty Publications and Research
Locomotory muscles typically operate over a narrow range of contraction frequencies, characterized by the predominant fiber types and functional roles. The highest documented frequencies in the synchronous soundproducing muscles of insects (550 Hz) and toadfish (200 Hz) far exceed the contraction frequencies observed in weightbearing locomotory muscles, which have maximum documented frequencies below 1530 Hz. Laws of scaling, however, predict that smaller arthropods may employ stride frequencies exceeding this range. In this study we measured running speed and stride frequency in two undescribed species of teneriffiid mites from the coastal sage scrub of southern California. Relative speeds of both species ...
Direct Measurements Of Island Growth And StepEdge Barriers In Colloidal Epitaxy, Rajesh Ganapathy, Mark R. Buckley, Sharon J. Gerbode, Itai Cohen
Direct Measurements Of Island Growth And StepEdge Barriers In Colloidal Epitaxy, Rajesh Ganapathy, Mark R. Buckley, Sharon J. Gerbode, Itai Cohen
All HMC Faculty Publications and Research
Epitaxial growth, a bottomup selfassembly process for creating surface nano and microstructures, has been extensively studied in the context of atoms. This process, however, is also a promising route to selfassembly of nanometer and micrometerscale particles into microstructures that have numerous technological applications. To determine whether atomic epitaxial growth laws are applicable to the epitaxy of larger particles with attractive interactions, we investigated the nucleation and growth dynamics of colloidal crystal films with singleparticle resolution. We show quantitatively that colloidal epitaxy obeys the same twodimensional island nucleation and growth laws that govern atomic epitaxy. However, we found that in colloidal ...
SelfOrganized Criticality In Sheared Suspensions, L. Corté, Sharon J. Gerbode, W. Man, D. J. Pine
SelfOrganized Criticality In Sheared Suspensions, L. Corté, Sharon J. Gerbode, W. Man, D. J. Pine
All HMC Faculty Publications and Research
Recent studies reveal that suspensions of neutrally buoyant nonBrownian particles driven by slow periodic shear can undergo a dynamical phase transition between a fluctuating irreversible steady state and an absorbing reversible state. Using a computer model, we show that such systems exhibit selforganized criticality when a finite particle sedimentation velocity v_{s} is introduced. Under periodic shear, these systems evolve, without external intervention, towards the sheardependent critical concentration ϕ_{c} as v_{s} is reduced. This state is characterized by powerlaw distributions in the lifetime and size of fluctuating clusters. Experiments exhibit similar behavior and, as v_{s} is reduced ...
How Much Can Guided Modes Enhance Absorption In Thin Solar Cells?, Peter N. Saeta, Vivian E. Ferry, Domenico Pacifici, Jeremy N. Munday, Harry A. Atwater
How Much Can Guided Modes Enhance Absorption In Thin Solar Cells?, Peter N. Saeta, Vivian E. Ferry, Domenico Pacifici, Jeremy N. Munday, Harry A. Atwater
All HMC Faculty Publications and Research
Absorption enhancement in thin metalbacked solar cells caused by dipole scatterers embedded in the absorbing layer is studied using a semianalytical approach. The method accounts for changes in the radiation rate produced by layers above and below the dipole, and treats incoherently the subsequent scattering of light in guided modes from other dipoles. We find large absorption enhancements for strongly coupled dipoles, exceeding the ergodic limit in some configurations involving lossless dipoles. An antireflectioncoated 100nm layer of aSi:H on Ag absorbs up to 87% of incident abovegap light. Thin layers of both strong and weak absorbers show similar strongly ...
Sum Rules And Universality In ElectronModulated Acoustic Phonon Interaction In A FreeStanding Semiconductor Plate, Shigeyasu Uno, Darryl H. Yong, Nobuya Mori
Sum Rules And Universality In ElectronModulated Acoustic Phonon Interaction In A FreeStanding Semiconductor Plate, Shigeyasu Uno, Darryl H. Yong, Nobuya Mori
All HMC Faculty Publications and Research
Analysis of acoustic phonons modulated due to the surfaces of a freestanding semiconductor plate and their deformationpotential interaction with electrons are presented. The form factor for electronmodulated acoustic phonon interaction is formulated and analyzed in detail. The form factor at zero inplane phonon wave vector satisfies sum rules regardless of electron wave function. The form factor is larger than that calculated using bulk phonons, leading to a higher scattering rate and lower electron mobility. When properly normalized, the form factors lie on a universal curve regardless of plate thickness and material.
The Initial And Final States Of Electron And Energy Transfer Processes: Diabatization As Motivated By SystemSolvent Interactions, Joseph E. Subotnik, Robert J. Cave, Ryan P. Steele, Neil Shenvi
The Initial And Final States Of Electron And Energy Transfer Processes: Diabatization As Motivated By SystemSolvent Interactions, Joseph E. Subotnik, Robert J. Cave, Ryan P. Steele, Neil Shenvi
All HMC Faculty Publications and Research
For a system which undergoes electron or energy transfer in a polar solvent, we define the diabatic states to be the initial and final states of the system, before and after the nonequilibrium transfer process. We consider two models for the systemsolvent interactions: A solvent which is linearly polarized in space and a solvent which responds linearly to the system. From these models, we derive two new schemes for obtaining diabatic states from ab initio calculations of the isolated system in the absence of solvent. These algorithms resemble standard approaches for orbital localization, namely, the Boys and Edmiston–Ruedenberg (ER ...
Generation Of Mie Size Microdroplet Aerosols With Applications In LaserDriven Fusion Experiments, Andrew P. Higginbotham '09, O. Semonin '06, S. Bruce '08, C. Chan '08, M. Maindi '07, Thomas D. Donnelly, M. Maurer, W. Bang, I. Churina, J. Osterholz, I. Kim, A. C. Bernstein, T. Ditmire
Generation Of Mie Size Microdroplet Aerosols With Applications In LaserDriven Fusion Experiments, Andrew P. Higginbotham '09, O. Semonin '06, S. Bruce '08, C. Chan '08, M. Maindi '07, Thomas D. Donnelly, M. Maurer, W. Bang, I. Churina, J. Osterholz, I. Kim, A. C. Bernstein, T. Ditmire
All HMC Faculty Publications and Research
We have developed a tunable source of Mie scale microdroplet aerosols that can be used for the generation of energetic ions. To demonstrate this potential, a terawatt Ti:Al_{2}O_{3} laser focused to 2×10^{19} W/cm^{2} was used to irradiate heavy water (D_{2}O) aerosols composed of micronscale droplets. Energetic deuterium ions, which were generated in the laserdroplet interaction, produced deuteriumdeuterium fusion with approximately 2×10^{3} fusion neutrons measured per joule of incident laser energy.
Thermal Links For The Implementation Of An Optical Refrigerator, John Parker, David Mar, Steven Von Der Porten, John Hankinson, Kevin Byram, Chris Lee, Michael K. Mayeda, Richard C. Haskell, Qimin Yang, Scott R. Greenfield, Richard I. Epstein
Thermal Links For The Implementation Of An Optical Refrigerator, John Parker, David Mar, Steven Von Der Porten, John Hankinson, Kevin Byram, Chris Lee, Michael K. Mayeda, Richard C. Haskell, Qimin Yang, Scott R. Greenfield, Richard I. Epstein
All HMC Faculty Publications and Research
Optical refrigeration has been demonstrated by several groups of researchers, but the cooling elements have not been thermally linked to realistic heat loads in ways that achieve the desired temperatures. The ideal thermal link will have minimal surface area, provide complete optical isolation for the load, and possess high thermal conductivity. We have designed thermal links that minimize the absorption of fluoresced photons by the heat load using multiple mirrors and geometric shapes including a hemisphere, a kinked waveguide, and a tapered waveguide. While total link performance is dependent on additional factors, we have observed net transmission of photons with ...
Stability Of Traveling Waves In Thin Liquid Films Driven By Gravity And Surfactant, Ellen Peterson, Michael Shearer, Thomas P. Witelski, Rachel Levy
Stability Of Traveling Waves In Thin Liquid Films Driven By Gravity And Surfactant, Ellen Peterson, Michael Shearer, Thomas P. Witelski, Rachel Levy
All HMC Faculty Publications and Research
A thin layer of fluid flowing down a solid planar surface has a free surface height described by a nonlinear PDE derived via the lubrication approximation from the Navier Stokes equations. For thin films, surface tension plays an important role both in providing a significant driving force and in smoothing the free surface. Surfactant molecules on the free surface tend to reduce surface tension, setting up gradients that modify the shape of the free surface. In earlier work [12, 13J a traveling wave was found in which the free surface undergoes three sharp transitions, or internal layers, and the surfactant ...
Constructing Diabatic States From Adiabatic States: Extending Generalized Mulliken–Hush To Multiple Charge Centers With Boys Localization, Joseph E. Subotnik, Robert J. Cave, Sina Yeganeh, Mark A. Ratner
Constructing Diabatic States From Adiabatic States: Extending Generalized Mulliken–Hush To Multiple Charge Centers With Boys Localization, Joseph E. Subotnik, Robert J. Cave, Sina Yeganeh, Mark A. Ratner
All HMC Faculty Publications and Research
This article shows that, although Boys localization is usually applied to singleelectron orbitals, the Boys method itself can be applied to many electron molecular states. For the twostate chargetransfer problem, we show analytically that Boys localization yields the same chargelocalized diabatic states as those found by generalized Mulliken–Hush theory. We suggest that for future work in electron transfer, where systems have more than two charge centers, one may benefit by using a variant of Boys localization to construct diabatic potential energy surfaces and extract electronic coupling matrix elements. We discuss two chemical examples of Boys localization and propose a ...
Synthesis And Assembly Of Nonspherical Hollow Silica Colloids Under Confinement, Stephanie H. Lee, Sharon J. Gerbode, Bettina S. John, Angie K. Wolfgang, Fernando A. Escobedo, Itai Cohen, Chekesha M. Liddell
Synthesis And Assembly Of Nonspherical Hollow Silica Colloids Under Confinement, Stephanie H. Lee, Sharon J. Gerbode, Bettina S. John, Angie K. Wolfgang, Fernando A. Escobedo, Itai Cohen, Chekesha M. Liddell
All HMC Faculty Publications and Research
Hard peanutshaped colloids were synthesized and organized into a degenerate crystal (DC), a phase previously observed only in simulations. In this structure, particle lobes tile a triangular lattice while their orientations uniformly populate the three underlying crystalline directions.
Restricted Dislocation Motion In Crystals Of Colloidal Dimer Particles, Sharon J. Gerbode, Stephanie H. Lee, Chekesha M. Liddell, Itai Cohen
Restricted Dislocation Motion In Crystals Of Colloidal Dimer Particles, Sharon J. Gerbode, Stephanie H. Lee, Chekesha M. Liddell, Itai Cohen
All HMC Faculty Publications and Research
Received 2 April 2008; published 1 August 2008; corrected 1 October 2008
At high area fractions, monolayers of colloidal dimer particles form a degenerate crystal (DC) structure in which the particle lobes occupy triangular lattice sites while the particles are oriented randomly along any of the three lattice directions. We report that dislocation glide in DCs is blocked by certain particle orientations. The mean number of lattice constants between such obstacles is Z̅ _{exp}=4.6±0.2 in experimentally observed DC grains and Z̅ _{sim}=6.18±0.01 in simulated monocrystalline DCs. Dislocation propagation beyond these obstacles is ...
Computer Modeling And Analysis Of Thermal Link Performance For An Optical Refrigerator, Kevin Byram, David Mar, John Parker, Steven Von Der Porten, John Hankinson, Chris Lee, Kai Mayeda, Richard C. Haskell, Qimin Yang, Scott R. Greenfield, Richard I. Epstein
Computer Modeling And Analysis Of Thermal Link Performance For An Optical Refrigerator, Kevin Byram, David Mar, John Parker, Steven Von Der Porten, John Hankinson, Chris Lee, Kai Mayeda, Richard C. Haskell, Qimin Yang, Scott R. Greenfield, Richard I. Epstein
All HMC Faculty Publications and Research
We have used the thermal modeling tool in COMSOL Multiphysics to investigate factors that affect the thermal performance of the optical refrigerator. Assuming an ideal cooling element and a nonabsorptive dielectric trapping mirror, the three dominant heating factors are blackbody radiation from the surrounding environment, conductive heat transfer through mechanical supports, and the absorption of fluorescent photons transmitted through the thermal link. Laboratory experimentation coupled with computer modeling using Code V optical software have resulted in link designs capable of reducing the transmission to 0.04% of the fluoresced photons emitted toward the thermal link. The ideal thermal link will ...
Designs And Optical Tests Of Thermal Links For An Optical Refrigerator, John Parker, David Mar, Steven Von Der Porten, John Hankinson, Kevin Byram, Chris Lee, Kai Mayeda, Richard C. Haskell, Qimin Yang, Scott R. Greenfield, Richard I. Epstein
Designs And Optical Tests Of Thermal Links For An Optical Refrigerator, John Parker, David Mar, Steven Von Der Porten, John Hankinson, Kevin Byram, Chris Lee, Kai Mayeda, Richard C. Haskell, Qimin Yang, Scott R. Greenfield, Richard I. Epstein
All HMC Faculty Publications and Research
Dielectric mirror leakage at large angles of incidence limits the effectiveness of solid state optical refrigerators due to reheating caused by photon absorption in an attached load. In this paper, we present several thermally conductive link solutions to greatly reduce the net photon absorption. The Los Alamos Solid State Optical Refrigerator (LASSOR) has demonstrated cooling of a Yb/sup 3+/ doped ZBLANP glass to 208 K. We have designed optically isolating thermal link geometries capable of extending cooling to a typical heat load with minimal absorptive reheating, and we have tested the optical performance of these designs. A surrogate source ...
New Mechanism For Nonlocality From String Theory: UvIr Quantum Entanglement And Its Imprints On The Cmb, Gregory Minton '08, Vatche Sahakian
New Mechanism For Nonlocality From String Theory: UvIr Quantum Entanglement And Its Imprints On The Cmb, Gregory Minton '08, Vatche Sahakian
All HMC Faculty Publications and Research
Puff field theories (PFT) arise as the decoupling limits of D3 branes in a Melvin universe and exhibit spatially nonlocal dynamics. Unlike other realizations of nonlocality in string theory, PFTs have full SO(3) rotational symmetry. In this work, we analyze the strongly coupled regime of a PFT through gravitational holography. We find a novel mechanism at the heart of the phenomenon of nonlocality: a quantum entanglement of UV and IR dynamics. In the holographic bulk, this translates to an apparent horizon splitting the space into two regions—with the UV completion of the PFT sitting at the horizon. We ...
GravityDriven Thin Liquid Films With Insoluble Surfactant: Smooth Traveling Waves, Rachel Levy, Michael Shearer, Thomas P. Witelski
GravityDriven Thin Liquid Films With Insoluble Surfactant: Smooth Traveling Waves, Rachel Levy, Michael Shearer, Thomas P. Witelski
All HMC Faculty Publications and Research
The flow of a thin layer of fluid down an inclined plane is modified by the presence of insoluble surfactant. For any finite surfactant mass, traveling waves are constructed for a system of lubrication equations describing the evolution of the freesurface fluid height and the surfactant concentration. The oneparameter family of solutions is investigated using perturbation theory with three small parameters: the coefficient of surface tension, the surfactant diffusivity, and the coefficient of the gravitydriven diffusive spreading of the fluid. When all three parameters are zero, the nonlinear PDE system is hyperbolic/degenerateparabolic, and admits traveling wave solutions in which ...
Nonlinear Dynamics In Combinatorial Games: Renormalizing Chomp, Eric J. Friedman, Adam S. Landsberg
Nonlinear Dynamics In Combinatorial Games: Renormalizing Chomp, Eric J. Friedman, Adam S. Landsberg
WM Keck Science Faculty Papers
We develop a new approach to combinatorial games that reveals connections between such games and some of the central ideas of nonlinear dynamics: scaling behaviors, complex dynamics and chaos, universality, and aggregation processes. We take as our model system the combinatorial game Chomp, which is one of the simplest in a class of "unsolved" combinatorial games that includes Chess, Checkers, and Go. We discover that the game possesses an underlying geometric structure that "grows" (reminiscent of crystal growth), and show how this growth can be analyzed using a renormalization procedure adapted from physics. In effect, this methodology allows one to ...