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Physics

Biological Physics

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Displaying 126 - 150 of 197

Revision of the NIST Standard for 223Ra: New Measurements and Review of 2008 Data

July 1, 2015
Author(s)
Denis E. Bergeron, Jeffrey T. Cessna, Leticia S. Pibida
After discovering a discrepancy in the transfer standard currently being disseminated by the National Institute of Standards and Technology (NIST), we have performed a new primary standardization of the alpha-emitter 223Ra using Live-timed Anticoincidence

Proximal Capture Dynamics for a Single Biological Nanopore Sensor

June 23, 2015
Author(s)
John J. Kasianowicz
Single nanopore sensors enable capture and analysis of molecules that are driven to the pore entry from bulk solution. However, the distance between an analyte and the nanopore opening limits the detection efficiency. A theoretical basis for predicting

Chemically-Sensitive Bioimaging with Coherent Raman Scattering

April 29, 2015
Author(s)
Charles H. Camp, Marcus T. Cicerone
Raman scattering provides an intrinsic fingerprint of chemical composition. Spontaneous Raman spectroscopy has been used for many decades to interrogate biological materials and systems, but is not widely used for imaging due to relatively slow signal

Making digital phantoms with spectral and spatial light modulators for quantitative applications of hyperspectral optical medical imaging devices

March 6, 2015
Author(s)
Bonghwan Chon, fuyuki Tokumasu, Ji Youn Lee, David W. Allen, Joseph P. Rice, Jeeseong C. Hwang
We present a procedure to generate digital phantoms with a hyperspectral image projector (HIP) consisting of two liquid crystal on silicon (LCoS) spatial light modulators (SLMs). The digital phantoms are 3D image data cubes of the spatial distribution of

High Resolution Surface Plasmon Resonance Imaging for Single Cells

November 30, 2014
Author(s)
Alexander Peterson, Michael Halter, Alessandro Tona, Anne Plant
Background Surface plasmon resonance imaging (SPRI) is a label-free technique that can image refractive index changes at an interface. We have previously shown that SPRI can be used to study the dynamics of cell-substratum interactions. However

Inhibition of cellular proliferation and enhancement of hydrogen peroxide production in fibrosarcoma cell line by weak radio frequency magnetic fields

September 23, 2014
Author(s)
Pablo Castello, Iain Hill, Lucas Portelli, Frank Barnes, Robert J. Usselman, Carlos Martino
This study presents experimental data for the effects of weak radio frequency (RF) magnetic fields on hydrogen peroxide (H2O2) production and cellular growth rates of fibrosarcoma HT1080 cells in vitro. Cells were exposed either to 45mT static magnetic

An Average Enumeration Method of Hyperspectral Imaging Data for Quantitative Evaluation of Medical Device Surface Contamination

September 15, 2014
Author(s)
Hanh Le, Moon Kim, Jeeseong C. Hwang, Yi Yang, Pawneena U-Thainual, Jin Kang, Do-Hyun Kim
We propose a quantification method called Mapped Average Principal component analysis Score (MAPS) to enumerate the contamination coverage on common medical device surfaces. The method was adapted from conventional Principal Component Analysis (PCA) on non

A Candidate Reference Analytical Method for Quantification of Low Concentrations of Plasmid DNA by Exhaustive Counting of Single DNA Molecules in a Flow Stream

August 4, 2014
Author(s)
Hee-Bong Yoo, Dong-Geun Oh, Jae Yong Song, Mamoru Kawaharasaki, Jeeseong C. Hwang, In Chul Yang, Sang-Ryoul Park
This work demonstrates accurate measurement of the concentration of low-level plasmid DNA by counting individual DNA molecules using a high-sensitivity flow cytometric setup. Plasmid DNA is a widely used form of DNA, and its quantity often needs to be

High-Speed Coherent Raman Fingerprint Imaging of Biological Tissues

July 20, 2014
Author(s)
Charles H. Camp, Young J. Lee, John M. Heddleston, Christopher M. Hartshorn, Angela R. Hight Walker, Jeremy N. Rich, Justin D. Lathia, Marcus T. Cicerone
We have developed a coherent Raman imaging platform using broadband coherent anti-Stokes Raman scattering (BCARS) that provides an unprecedented combination of speed, sensitivity, and spectral breadth. The system utilizes a unique configuration of laser

Dose calibrator manufacturer-dependent bias in assays of 123I

March 26, 2014
Author(s)
Denis E. Bergeron, Jeffrey T. Cessna, Daniel B. Golas, Rheannan K. Young, Brian E. Zimmerman
Calibration factors for commercial ionization chambers (i.e. dose calibrators) were determined for a solution of 123I; the activity was based on the 1976 NBS standard. A link between the NIST standard and the International Reference System (SIR) was

Quantifying short-lived events in multistate ionic current measurements

January 7, 2014
Author(s)
Arvind K. Balijepalli, Jessica H. Benjamini, Andrew T. Cornio, Joseph W. Robertson, Kin P. Cheung, John J. Kasianowicz, Canute I. Vaz
We developed a generalized technique to characterize polymer!nanopore interactions via single channel ionic current measurements. Physical interactions between analytes, such as DNA, proteins, or synthetic polymers, and a nanopore cause multiple discrete

Measurement Traceability in Medical Physics

January 1, 2014
Author(s)
Lisa R. Karam
Medical physics, the joining of physics with healthcare, requires a level of quality assurance beyond many applications of the physical sciences. Always the health, and often the life, of the patient depends on the precise and accurate implementation of

Absolute calibration of optical power and fluence rate for PDT: Report of AAPM TG140

July 23, 2013
Author(s)
Marla L. Dowell, Timothy Zhu, Christopher Bonnerup, Valdir Colussi, Jarod Finlay, Lothar Lilge, Thomas Slowery, claudio sibata
This report is primarily concerned with methods for optical calibration of laser power and light fluence rate for continuous wave (CW) light sources, predominantly used in photodynamic therapy (PDT). Dosimetry of light is very important for PDT, however

Multicomponent Chemical Imaging of Pharmaceutical Solid Dosage Forms with Broadband CARS Microscopy

July 15, 2013
Author(s)
Christopher M. Hartshorn, Marcus T. Cicerone, Young J. Lee, Charles H. Camp, John M. Heddleston, Patrick Marsac, Tim Rhodes, Zhen Liu, Nicole Canfield
We compare broadband coherent anti-Stokes Raman scattering (BCARS) microscopy with spontaneous Raman microscopy for quantitative and qualitative assessment of multicomponent pharmaceuticals. Indomethacin was used as a model active pharmaceutical ingredient

Mapping the Vif-A3G interaction using peptide arrays: a basis for anti-HIV lead peptides

June 15, 2013
Author(s)
Jeeseong Hwang, Ji Y. Lee, Abigail E. Miller, Tali Reingewertz, Elena Britan-Rosich, Shahar Rotem-Bamberger, Mathias Viard, Robert Blumenthal, Assaf Friedler
Human apolipoprotein-B mRNA-editing catalytic polypeptide-like 3G (A3G) is a cytidine deaminase that restricts retroviruses, endogenous retro-elements and DNA viruses. A3G plays a key role in the anti- HIV-1 innate cellular immunity. The HIV-1 Vif protein

Engineering novel detectors and sensors for MRI

April 1, 2013
Author(s)
Gary Zabow, Chunqi Qian, Alan Koretsky
Increasing detection sensitivity and image contrast have always been major topics of research in MRI. In this perspective, we summarize two engineering approaches to make detectors and sensors that have potential to extend the capability of MRI. The first

Temperature sculpting in yoctoliter volumes

February 14, 2013
Author(s)
Joseph E. Reiner, Joseph W. Robertson, Daniel L. Burden, Lisa K. Burden, Arvind Balijepalli, John J. Kasianowicz
The ability to perturb large ensembles of molecules from equilibrium led to major advances in understanding reaction mechanisms in chemistry and biology. Here, we demonstrate the ability to control, measure, and make use of rapid temperature changes of

The Effects of Diffusion on an Exonuclease/Nanopore-Based DNA Sequencing Engine

December 7, 2012
Author(s)
Joseph E. Reiner, Joseph W. Robertson, Arvind Balijepalli, Daniel L. Burden, Bryon S. Drown, John J. Kasianowicz
The ability to electronically detect and characterize individual polynucleotides as they are driven through a single protein ion channel may eventually prove useful for rapidly sequencing DNA (base-by-base) in a ticker tape-like fashion. More recently, a
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