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Full-Text Articles in Physics

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 Jan 2011

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

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A popular method for generating micron-sized 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 Jan 2011

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

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Corneal blindness is a significant problem treated primarily by corneal transplants. Donor tissue supply is low, creating a growing need for an alternative. A tissue-engineered cornea made from patient-derived 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 small-diameter, aligned collagen fibers. In this study, we investigate the effect of scaffold nanostructure and composition ...


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 Feb 2008

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

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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 non-absorptive 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 ...


Certifications Offered By Cost Estimating Organizations, Donald S. Remer, Karen M. Ahle, Kevin J. Alley, John Silny, Karen Hsin Oct 2006

Certifications Offered By Cost Estimating Organizations, Donald S. Remer, Karen M. Ahle, Kevin J. Alley, John Silny, Karen Hsin

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There has been an increasing trend in professional and engineering circles to place greater emphasis on official credentials. These credentials commonly come in the form of certificates – documented recognition by a professional body that an engineer or other professional has the qualifications and technical knowledge to be a practitioner in that field. These certificates are somewhat analogous to merit badges in scouting – the certification is evidence that the holder has a certain minimum level of competence in the subject area. This review will help you decide what certifications are applicable to you and the requirements to obtain a certification.


Using Ultrasonic Atomization To Produce An Aerosol Of Micron-Scale Particles, Thomas D. Donnelly, J. Hogan '03, A. Mugler '04, M. Schubmehl '02, N. Schommer '04, Andrew J. Bernoff, S. Dasnurkar, T. Ditmire Nov 2005

Using Ultrasonic Atomization To Produce An Aerosol Of Micron-Scale Particles, Thomas D. Donnelly, J. Hogan '03, A. Mugler '04, M. Schubmehl '02, N. Schommer '04, Andrew J. Bernoff, S. Dasnurkar, T. Ditmire

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A device that uses ultrasonic atomization of a liquid to produce an aerosol of micron-scale droplets is described. This device represents a new approach to producing targets relevant to laser-driven fusion studies, and to rare studies of nonlinear optics in which wavelength-scale targets are irradiated. The device has also made possible tests of fluid dynamics models in a novel phase space. The distribution of droplet sizes produced by the device and the threshold power required for droplet production are shown to follow scaling laws predicted by fluid dynamics.


Immunogold Labeling To Enhance Contrast In Optical Coherence Microscopy Of Tissue Engineered Corneal Constructs, Chris B. Raub, Elizabeth J. Orwin, Richard C. Haskell Sep 2004

Immunogold Labeling To Enhance Contrast In Optical Coherence Microscopy Of Tissue Engineered Corneal Constructs, Chris B. Raub, Elizabeth J. Orwin, Richard C. Haskell

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Our lab has used an optical coherence microscope (OCM) to assess both the structure of tissue-engineered corneal constructs and their transparency. Currently, we are not able to resolve cells versus collagen matrix material in the images produced. We would like to distinguish cells in order to determine if they are viable while growing in culture and also if they are significantly contributing to the light scattering in the tissue. In order to do this, we are currently investigating the use of immunogold labeling. Gold nanoparticles are high scatterers and can create contrast in images. We have conjugated gold nanoparticles to ...


Intraocular Lens Case Designs, Donald S. Remer, Stephen S. Davis, Michael Bak '95, Ken Kalafus, Ilan Sabar, Khannan Suntharam, William Washington, Yu-Tung Wong Jan 1996

Intraocular Lens Case Designs, Donald S. Remer, Stephen S. Davis, Michael Bak '95, Ken Kalafus, Ilan Sabar, Khannan Suntharam, William Washington, Yu-Tung Wong

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IOLAB Corporation makes two types of intraocular lenses for the replacement of cataracts: one from polymethyl methacrylate (PMMA) and a newer one from silicone. IOLAB ships the lens to the doctor in a two-piece case made from polycarbonate. At a price of $0.53 per case, IOLAB spends about $270,000 per year on lens cases (based on 1994 purchases of 500,000 cases). IOLAB asked us to reduce the cost of the existing lens case and to design a new case to protect and fold the silicone lens. We designed three items.


Distortion And Evolution Of A Localized Vortex In An Irrotational Flow, Joseph F. Lingevitch, Andrew J. Bernoff May 1995

Distortion And Evolution Of A Localized Vortex In An Irrotational Flow, Joseph F. Lingevitch, Andrew J. Bernoff

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This paper examines the interaction of an axisymmetric vortex monopole, such as a Lamb vortex, with a background irrotational flow. At leading order, the monopole is advected with the background flow velocity at the center of vorticity. However, inhomogeneities of the flow will cause the monopole to distort. It is shown that a shear‐diffusion mechanism, familiar from the study of mixing of passive scalars, plays an important role in the evolution of the vorticity distribution. Through this mechanism, nonaxisymmetric vorticity perturbations which do not shift the center of vorticity are homogenized along streamlines on a Re1/3 time scale ...


Tissue Characterization And Imaging Using Photon Density Waves, Lars O. Svaasand, Bruce J. Tromberg, Richard C. Haskell, Tsong-Tseh Tsay, Michael W. Berns Feb 1993

Tissue Characterization And Imaging Using Photon Density Waves, Lars O. Svaasand, Bruce J. Tromberg, Richard C. Haskell, Tsong-Tseh Tsay, Michael W. Berns

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The optical properties of brain tissues have been evaluated by measuring the phase velocity and attenuation of harmonically modulated light. The phase velocity for photon density waves at 650-nm wavelength has been found to be in the range of 5 to 12% of the corresponding velocity in a nonscattering medium, and the optical penetration depth was in the range 2.9 to 5.2 mm. These results are used to predict the resolution of optical imaging of deep tissue structures by diffusely propagating incoherent photons. The results indicate that structures of a few millimeters in linear dimension can be identified ...


Measuring R And D Productivity, Richard A. Pappas, Donald S. Remer May 1985

Measuring R And D Productivity, Richard A. Pappas, Donald S. Remer

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Measuring the productivity of an R&D organization is extremely tricky. Productivity is usually defined as a ratio of an output, like number of cars produced on an assembly line, to an input, like the wages paid the workers. While R&D may have a measurable input, the output is often intangible and difficult to quantify. This is further complicated because the return from an R&D department may not be realized for one or two decades,which means the time lag is much higher than in factory measurements. Furthermore, many researchers believe that this kind of measurement may be ...


Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Thermal Stress Analysis, A. Ballantyne, H.A. Hyman, Clive L. Dym, R.C. Southworth Jan 1985

Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Thermal Stress Analysis, A. Ballantyne, H.A. Hyman, Clive L. Dym, R.C. Southworth

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This paper examines the effects of thermal loading and time history upon the thermal stresses developed in lithographic mask structures as would be expected under irradiation by intense soft x rays. The objective of this work was to examine the phenomenology of the interaction and to evaluate the limits placed upon mask dosage. The mechanics of mask failure are examined in terms of single pulse and cumulative, or fatigue, effects. A number of prototypical mask structures are investigated, which show that the application of intense pulsed sources to x‐ray lithography does not reduce the potential utility of the techique ...


Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Dynamic Response, Clive L. Dym, A. Ballantyne Jan 1985

Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Dynamic Response, Clive L. Dym, A. Ballantyne

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This paper addresses the issue of the dynamic response of thin lithographic mask structures to thermally induced stress fields. In particular, the impact of repetitively pulsed x‐ray sources are examined: the short duration (1–100 nsec) pulses induce large step changes in mask temperatures, which can, in turn, induce a dynamic response. The impact of conductive cooling of the mask is to reduce the repetitively pulsed problem to a series of isolated nearly identical thermal impulses of duration approximately equal to the cooling time. The importance of self‐weight and prestress is examined, and an analysis of the nonlinear ...