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Articles 1 - 30 of 109

Full-Text Articles in Physics

Measurement Of Unpolarized And Polarized Cross Sections For Deeply Virtual Compton Scattering On The Proton At Jefferson Laboratory With Clas, N. Saylor, B. Hirlinger, B. Guegan, V. D. Burkert, L. Elouadrhiri, M. Garcon, F. X. Girod, M. Guidal, Gerard P. Gilfoyle, Et. Al. Oct 2018

Measurement Of Unpolarized And Polarized Cross Sections For Deeply Virtual Compton Scattering On The Proton At Jefferson Laboratory With Clas, N. Saylor, B. Hirlinger, B. Guegan, V. D. Burkert, L. Elouadrhiri, M. Garcon, F. X. Girod, M. Guidal, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

This paper reports the measurement of polarized and unpolarized cross sections for the ep→e′p′γ reaction, which is composed of deeply virtual Compton scattering (DVCS) and Bethe-Heitler (BH) processes, at an electron beam energy of 5.88 GeV at the Thomas Jefferson National Accelerator Facility using the Large Acceptance Spectrometer CLAS. The unpolarized cross sections and polarized cross section differences have been measured over broad kinematics, 0.10 < xB < 0.58, 1.0 < Q2 <4.8 GeV2 and 0.09<−t <2.00 GeV2. The results are found to be consistent with previous CLAS data, and these new data are discussed in the framework of the generalized ...


Measurements Of The Gamma(Upsilon)P -> P ’Pi(+)Pi(- )Cross Section With The Clas Detector For 0.4 Gev2 < Q(2) < 1.0 Gev2 And 1.3 Gev < W < 1.825 Gev, G. Fedotov, Iu A. Skorodumina, V. D. Burkert, R. W. Gothe, K. Hicks, V. Mokeev, S. Adhikari, Gerard P. Gilfoyle, Et. Al. Aug 2018

Measurements Of The Gamma(Upsilon)P -> P ’Pi(+)Pi(- )Cross Section With The Clas Detector For 0.4 Gev2 < Q(2) < 1.0 Gev2 And 1.3 Gev < W < 1.825 Gev, G. Fedotov, Iu A. Skorodumina, V. D. Burkert, R. W. Gothe, K. Hicks, V. Mokeev, S. Adhikari, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

New results on the single-differential and fully integrated cross sections for the process γvp -> p'π+π- are presented. The experimental data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the kinematic region of the reaction invariant mass W from 1.3 to 1.825 GeV and the photon virtuality Q2 from 0.4 to 1.0 GeV2. The cross sections were obtained in narrow Q2 bins (0.05 GeV2) with the smallest statistical uncertainties achieved in double-pion electroproduction experiments to date. The results were found to be ...


Exclusive Photoproduction Of Pi Degrees Up To Large Values Of Mandelstam Variables S, T, And U With Clas, M. C. Kunkel, M. J. Amaryan, I. I. Strakovsky, J. Ritman, G. R. Goldstein, K. P. Adhikari, S. Adhikari, Gerard P. Gilfoyle, Et. Al. Jul 2018

Exclusive Photoproduction Of Pi Degrees Up To Large Values Of Mandelstam Variables S, T, And U With Clas, M. C. Kunkel, M. J. Amaryan, I. I. Strakovsky, J. Ritman, G. R. Goldstein, K. P. Adhikari, S. Adhikari, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

Exclusive photoproduction cross sections have been measured for the process γp ->0 [e+ e- (γ)] with the Dalitz decay final state using tagged photon energies in the range of = 1.275 – 5.425 GeV. The complete angular distribution of the final state π0, for the entire photon energy range up to large values of t and u, has been measured for the first time. The data obtained show that the cross section dσ / dt, at mid to large angles, decreases with energy as s-6.89 +/- 0.26. This is in agreement with the perturbative QCD quark ...


Semi-Inclusive Pi(0) Target And Beam-Target Asymmetries From 6 Gev Electron Scattering With Clas, S. Jawalkar, S. Koirala, H. Avakian, P. Bosted, K. A. Griffioen, C. Keith, S. E. Kuhn, Gerard P. Gilfoyle, Et. Al. Jul 2018

Semi-Inclusive Pi(0) Target And Beam-Target Asymmetries From 6 Gev Electron Scattering With Clas, S. Jawalkar, S. Koirala, H. Avakian, P. Bosted, K. A. Griffioen, C. Keith, S. E. Kuhn, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic 14NH3 target, and extracted double and single target spin asymmetries for ep→e′ π0 X in multidimensional bins in four-momentum transfer (1.0 2 < 3.2 GeV2), Bjorken -x (0.12 < x < 0.48), hadron energy fraction (0.4 < z 0.7), tranverse pion meomentum (0 < PT < 1.0 GeV), and azimuthal angle ϕh between the lepton scattering and hadron production planes. We extracted asymmetries as a function of both ...


Electrostatic Alignment Of Electrospun Peo Fibers By The Gap Method Increases Individual Fiber Modulus In Comparison To Non-Aligned Fibers Of Similar Diameter, Christopher Fryer, Meghan Scharnagl, Christine C. Helms Jun 2018

Electrostatic Alignment Of Electrospun Peo Fibers By The Gap Method Increases Individual Fiber Modulus In Comparison To Non-Aligned Fibers Of Similar Diameter, Christopher Fryer, Meghan Scharnagl, Christine C. Helms

Physics Faculty Publications

Studies on the alignment, physical and mechanical properties of individual electrospun fibers provide insight to their formation, production and optimization. Here we measure the alignment, diameter and modulus of individual fibers formed using the electrostatic gap method. We find electrostatic alignment produces fibers with a smaller diameter than their nonaligned counterparts have. Therefore, due to the dependence of fiber modulus on diameter aligned fibers have a higher modulus. Furthermore, we show that aligned and nonaligned fibers of the similar diameter have different moduli. Aligned fibers have a modulus 1.5 to 2 times larger than nonaligned fibers of the similar ...


Hard Exclusive Pion Electroproduction At Backward Angles With Clas, K. M. Park, R. W. Gothe, B. Pire, K. Semenov-Tian-Shansky, J. -M. Laget, K. P. Adhikari, Gerard P. Gilfoyle, Et. Al. May 2018

Hard Exclusive Pion Electroproduction At Backward Angles With Clas, K. M. Park, R. W. Gothe, B. Pire, K. Semenov-Tian-Shansky, J. -M. Laget, K. P. Adhikari, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We report on the first measurement of cross sections for exclusive deeply virtual pion electroproduction off the proton, ep→e′nπ+, above the resonance region at backward pion center-of-mass angles. The φπ⁎-dependent cross sections were measured, from which we extracted three combinations of structure functions of the proton. Our results are compatible with calculations based on nucleon-to-pion transition distribution amplitudes (TDAs). These non-perturbative objects are defined as matrix elements of three-quark-light-cone-operators and characterize partonic correlations with a particular emphasis on baryon charge distribution inside a nucleon. Keywords: TDA, Exclusive single pion, Eletroproduction, CLAS


Measurement Of The Beam Asymmetry Sigma And The Target Asymmetry T In The Photoproduction Of Omega Mesons Off The Proton Using Clas At Jefferson Laboratory, P. Roy, Z. Akbar, S. Park, V. Crede, A. V. Anisovich, I. Denisenko, E. Klempt, Gerard P. Gilfoyle May 2018

Measurement Of The Beam Asymmetry Sigma And The Target Asymmetry T In The Photoproduction Of Omega Mesons Off The Proton Using Clas At Jefferson Laboratory, P. Roy, Z. Akbar, S. Park, V. Crede, A. V. Anisovich, I. Denisenko, E. Klempt, Gerard P. Gilfoyle

Physics Faculty Publications

The photoproduction of omega mesons off the proton has been studied in the reaction γp -> pω using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the target asymmetry T has been measured in photoproduction from the decay ω -> π+π-π0, using a transversely polarized target with energies ranging from just above the reaction threshold up to 2.8 GeV. Significant nonzero values are observed for these asymmetries, reaching about 30-40% in the third-resonance region. New measurements for the photon-beam asymmetry Σ are ...


The Radio Synchrotron Background: Conference Summary And Report, Jack Singal, J. Haider, M. Ajello, D. R. Ballantyne, Emory F. Bunn, J. Condon, J. Dowell, Et. Al. Mar 2018

The Radio Synchrotron Background: Conference Summary And Report, Jack Singal, J. Haider, M. Ajello, D. R. Ballantyne, Emory F. Bunn, J. Condon, J. Dowell, Et. Al.

Physics Faculty Publications

We summarize the radio synchrotron background workshop that took place 2017 July 19–21 at the University of Richmond. This first scientific meeting dedicated to the topic was convened because current measurements of the diffuse radio monopole reveal a surface brightness that is several times higher than can be straightforwardly explained by known Galactic and extragalactic sources and processes, rendering it by far the least well understood photon background at present. It was the conclusion of a majority of the participants that the radio monopole level is at or near that reported by the ARCADE 2 experiment and inferred from ...


Double K-S(0) Photoproduction Off The Proton At Clas, S. Chandavar, J. T. Goetz, K. Hicks, D. Keller, M. C. Kunkel, M. Paolone, D. P. Weygand, Gerard P. Gilfoyle, Et. Al. Feb 2018

Double K-S(0) Photoproduction Off The Proton At Clas, S. Chandavar, J. T. Goetz, K. Hicks, D. Keller, M. C. Kunkel, M. Paolone, D. P. Weygand, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

The f0 (1500) meson resonance is one of several contenders to have significant mixing with the lightest glueball. This resonance is well established from several previous experiments. Here we present the first photoproduction data for the f0 (1500) via decay into the K-S(0) K-S(0) channel using the CLAS detector. The reaction γp -> fJp -> K-S(0) K-S(0) p, where J = 0,2, was measured with photon energies from 2.7-5.1 GeV. A clear peak is seen at 1500 MeV in the background subtracted invariant mass spectra of the two kaons. This is enhanced ...


Erythrocytes And Vascular Function: Oxygen And Nitric Oxide, Christine C. Helms, M. T. Gladwin, Daniel B. Kim-Shapiro Feb 2018

Erythrocytes And Vascular Function: Oxygen And Nitric Oxide, Christine C. Helms, M. T. Gladwin, Daniel B. Kim-Shapiro

Physics Faculty Publications

Erythrocytes regulate vascular function through the modulation of oxygen delivery and the scavenging and generation of nitric oxide (NO). First, hemoglobin inside the red blood cell binds oxygen in the lungs and delivers it to tissues throughout the body in an allosterically regulated process, modulated by oxygen, carbon dioxide and proton concentrations. The vasculature responds to low oxygen tensions through vasodilation, further recruiting blood flow and oxygen carrying erythrocytes. Research has shown multiple mechanisms are at play in this classical hypoxic vasodilatory response, with a potential role of red cell derived vasodilatory molecules, such as nitrite derived nitric oxide and ...


Hill Functions For Stochastic Gene Regulatory Networks From Master Equations With Split Nodes And Time-Scale Separation, Ovidiu Lipan, Cameron Ferwerda Feb 2018

Hill Functions For Stochastic Gene Regulatory Networks From Master Equations With Split Nodes And Time-Scale Separation, Ovidiu Lipan, Cameron Ferwerda

Physics Faculty Publications

The deterministic Hill function depends only on the average values of molecule numbers. To account for the fluctuations in the molecule numbers, the argument of the Hill function needs to contain the means, the standard deviations, and the correlations. Here we present a method that allows for stochastic Hill functions to be constructed from the dynamical evolution of stochastic biocircuits with specific topologies. These stochastic Hill functions are presented in a closed analytical form so that they can be easily incorporated in models for large genetic regulatory networks. Using a repressive biocircuit as an example, we show by Monte Carlo ...


Measurement Of The Q(2) Dependence Of The Deuteron Spin Structure Function G(1) And Its Moments At Low Q(2) With Clas, K. P. Adhikari, A. Deur, L. El Fassi, H. Kang, S. E. Kuhn, M. Ripani, K. Slifer, Gerard P. Gilfoyle, Et. Al. Feb 2018

Measurement Of The Q(2) Dependence Of The Deuteron Spin Structure Function G(1) And Its Moments At Low Q(2) With Clas, K. P. Adhikari, A. Deur, L. El Fassi, H. Kang, S. E. Kuhn, M. Ripani, K. Slifer, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We measured the g1 spin structure function of the deuteron at low Q2, where QCD can be approximated with chiral perturbation theory (χPT). The data cover the resonance region, up to an invariant mass of W ≈ 1.9  GeV. The generalized Gerasimov-Drell-Hearn sum, the moment Γd1 and the spin polarizability γ0d are precisely determined down to a minimum Q2 of 0.02  GeV2 for the first time, about 2.5 times lower than that of previous data. We compare them to several χPT calculations and models. These results are the first ...


Measuring Polarized Emission In Clusters In The Cmb S4 Era, Louis Thibaut, Emory F. Bunn, Benjamin Wandelt, Joseph Silk Dec 2017

Measuring Polarized Emission In Clusters In The Cmb S4 Era, Louis Thibaut, Emory F. Bunn, Benjamin Wandelt, Joseph Silk

Physics Faculty Publications

The next generation of CMB experiments (CMB Stage-4) will produce a Sunyaev-Zel’dovich (SZ) cluster catalog containing ∼105 objects, two orders of magnitudes more than currently available. In this paper, we discuss the detectability of the polarized signal generated by scattering of the CMB quadrupole on the cluster electron gas using this catalog. We discuss the possibility of using this signal to measure the relationship between cluster optical depth and mass. We find that the area of observation of S4 maximizes the signal-to-noise (S/N) on the polarized signal but that this S/N is extremely small for an individual ...


Pure E And B Polarization Maps Via Wiener Filtering, Emory F. Bunn, Benjamin Wandelt Aug 2017

Pure E And B Polarization Maps Via Wiener Filtering, Emory F. Bunn, Benjamin Wandelt

Physics Faculty Publications

In order to draw scientific conclusions from observations of cosmic microwave background (CMB) polarization,it is necessary to separate the contributions of the E and B components of the data. For data with incomplete sky coverage, there are ambiguous modes, which can be sourced by either E or B signals. Techniques exist for producing “pure” E and B maps, which are guaranteed to be free of cross-contamination, although the standard method, which involves constructing an eigenbasis, has a high computational cost. We show that such pure maps can be thought of as resulting from the application of a Wiener filter ...


Analysis Of A Custom Support Vector Machine For Photometric Redshift Estimation And The Inclusion Of Galaxy Shape Information, Jack Singal, Evan Jones Jan 2017

Analysis Of A Custom Support Vector Machine For Photometric Redshift Estimation And The Inclusion Of Galaxy Shape Information, Jack Singal, Evan Jones

Physics Faculty Publications

Aims. We present a custom support vector machine classification package for photometric redshift estimation, including comparisons with other methods. We also explore the efficacy of including galaxy shape information in redshift estimation. Support vector machines, a type of machine learning, utilize optimization theory and supervised learning algorithms to construct predictive models based on the information content of data in a way that can treat different input features symmetrically, which can be a useful estimator of the information contained in additional features beyond photometry, such as those describing the morphology of galaxies.

Methods. The custom support vector machine package we have ...


Temperature Tuning From Direct To Inverted Bistable Electroluminescence In Resonant Tunneling Diodes, F. Hartmann, A. Pfenning, Mariama Rebello Sousa Dias, F. Langer, S. Höfling, M. Kamp, L. Worschech, L. K. Castelano, G. E. Marques, V. Lopez-Richard Jan 2017

Temperature Tuning From Direct To Inverted Bistable Electroluminescence In Resonant Tunneling Diodes, F. Hartmann, A. Pfenning, Mariama Rebello Sousa Dias, F. Langer, S. Höfling, M. Kamp, L. Worschech, L. K. Castelano, G. E. Marques, V. Lopez-Richard

Physics Faculty Publications

We study the electroluminescence (EL) emission of purely n-doped resonant tunneling diodes in a wide temperature range. The paper demonstrates that the EL originates from impact ionization and radiative recombination in the extended collector region of the tunneling device. Bistable currentvoltage response and EL are detected and their respective high and low states are tuned under varying temperature. The bistability of the EL intensity can be switched from direct to inverted with respect to the tunneling current and the optical on/off ratio can be enhanced with increasing temperature. One order of magnitude amplification of the optical on/off ratio ...


Splitting Nodes And Linking Channels: A Method For Assembling Biocircuits From Stochastic Elementary Units, Cameron Ferwerda, Ovidiu Lipan Nov 2016

Splitting Nodes And Linking Channels: A Method For Assembling Biocircuits From Stochastic Elementary Units, Cameron Ferwerda, Ovidiu Lipan

Physics Faculty Publications

Akin to electric circuits, we construct biocircuits that are manipulated by cutting and assembling channels through which stochastic information flows. This diagrammatic manipulation allows us to create a method which constructs networks by joining building blocks selected so that (a) they cover only basic processes; (b) it is scalable to large networks; (c) the mean and variance-covariance from the Pauli master equation form a closed system; and (d) given the initial probability distribution, no special boundary conditions are necessary to solve the master equation. The method aims to help with both designing new synthetic signaling pathways and quantifying naturally existing ...


The Mid-Infrared Luminosity Evolution And Luminosity Function Of Quasars With Wise And Sdss, Jack Singal Nov 2016

The Mid-Infrared Luminosity Evolution And Luminosity Function Of Quasars With Wise And Sdss, Jack Singal

Physics Faculty Publications

We determine the 22 μm luminosity evolution and luminosity function for quasars from a data set of over 20,000 objects obtained by combining flux-limited Sloan Digital Sky Survey optical and Wide field Infrared Survey Explorer mid-infrared data. We apply methods developed in previous works to access the intrinsic population distributions non-parametrically, taking into account the truncations and correlations inherent in the data. We find that the population of quasars exhibits positive luminosity evolution with redshift in the mid-infrared, but with considerably less mid-infrared evolution than in the optical or radio bands. With the luminosity evolutions accounted for, we ...


Exposure Of Fibrinogen And Thrombin To Nitric Oxide Donor Prolinonoate Affects Fibrin Clot Properties, Christine C. Helms, Shannon Kapadia, Anne C. Gilmore, Zhexi Lu, Swati Basu, Daniel B. Kim-Shapiro Oct 2016

Exposure Of Fibrinogen And Thrombin To Nitric Oxide Donor Prolinonoate Affects Fibrin Clot Properties, Christine C. Helms, Shannon Kapadia, Anne C. Gilmore, Zhexi Lu, Swati Basu, Daniel B. Kim-Shapiro

Physics Faculty Publications

Fibrin fibers form the structural backbone of blood clots. The structural properties of fibrin clots are highly dependent on formation kinetics. Environmental factors such as protein concentration, pH, salt, and protein modification, to name a few, can affect fiber kinetics through altered fibrinopeptide release, monomer association, and/or lateral aggregation. The objective of our study was to determine the effect of thrombin and fibrinogen exposed to nitric oxide on fibrin clot properties. ProliNONOate (5 [mu]mol/l) was added to fibrinogen and thrombin before clot initiation and immediately following the addition of thrombin to the fibrinogen solution. Resulting fibrin fibers ...


Light Sensitive Memristor With Bi-Directional And Wavelength-Dependent Conductance Control, P. Maier, F. Hartmann, Mariama Rebello Sousa Dias, M. Emmerling, C. Schneider, L. K. Castelano, M. Kamp, G. E. Marques, V. Lopez-Richard, L. Worschech, S. Höfling Jan 2016

Light Sensitive Memristor With Bi-Directional And Wavelength-Dependent Conductance Control, P. Maier, F. Hartmann, Mariama Rebello Sousa Dias, M. Emmerling, C. Schneider, L. K. Castelano, M. Kamp, G. E. Marques, V. Lopez-Richard, L. Worschech, S. Höfling

Physics Faculty Publications

We report the optical control of localized charge on positioned quantum dots in an electro-photosensitive memristor. Interband absorption processes in the quantum dot barrier matrix lead to photogenerated electron-hole-pairs that, depending on the applied bias voltage, charge or discharge the quantum dots and hence decrease or increase the conductance. Wavelength-dependent conductance control is observed by illumination with red and infrared light, which leads to charging via interband and discharging via intraband absorption. The presented memristor enables optical conductance control and may thus be considered for sensory applications in artificial neural networks as light-sensitive synapses or optically tunable memories.


Mimicking Of Pulse Shape-Dependent Learning Rules With A Quantum Dot Memristor, P. Maier, F. Hartmann, Mariama Rebello Sousa Dias, M. Emmerling, C. Schneider, L. K. Castelano, M. Kamp, G. E. Marques, V. Lopez-Richard, S. Höfling Jan 2016

Mimicking Of Pulse Shape-Dependent Learning Rules With A Quantum Dot Memristor, P. Maier, F. Hartmann, Mariama Rebello Sousa Dias, M. Emmerling, C. Schneider, L. K. Castelano, M. Kamp, G. E. Marques, V. Lopez-Richard, S. Höfling

Physics Faculty Publications

We present the realization of four different learning rules with a quantum dot memristor by tuning the shape, the magnitude, the polarity and the timing of voltage pulses. The memristor displays a large maximum to minimum conductance ratio of about 57 000 at zero bias voltage. The high and low conductances correspond to different amounts of electrons localized in quantum dots, which can be successively raised or lowered by the timing and shapes of incoming voltage pulses. Modifications of the pulse shapes allow altering the conductance change in dependence on the time difference. Hence, we are able to mimic different ...


A Determination Of The Gamma-Ray Flux And Photon Spectral Index Distributions Of Blazars From The Fermi-Lat 3lac, Jack Singal Nov 2015

A Determination Of The Gamma-Ray Flux And Photon Spectral Index Distributions Of Blazars From The Fermi-Lat 3lac, Jack Singal

Physics Faculty Publications

We present a determination of the distributions of gamma-ray photon flux – the so-called LogN–LogS relation – and photon spectral index for blazars, based on the third extragalactic source catalogue of the Fermi Gamma-ray Space Telescope's Large Area Telescope, and considering the photon energy range from 100 MeV to 100 GeV. The data set consists of the 774 blazars in the so-called Clean sample detected with a greater than approximately 7σ detection threshold and located above ±20° Galactic latitude. We use non-parametric methods verified in previous works to reconstruct the intrinsic distributions from the observed ones which account ...


Photocurrent-Voltage Relation Of Resonant Tunneling Diode Photodetectors, Andreas Pfenning, Favbian Hartmann, Mariama Rebello Sousa Dias, Fabian Langer, Martin Kamp, Leonardo Kleber Castelano, Victor Lopez-Richard, Gilmar Eugenio Marques, Sven Höfling, Lukas Worschech Jan 2015

Photocurrent-Voltage Relation Of Resonant Tunneling Diode Photodetectors, Andreas Pfenning, Favbian Hartmann, Mariama Rebello Sousa Dias, Fabian Langer, Martin Kamp, Leonardo Kleber Castelano, Victor Lopez-Richard, Gilmar Eugenio Marques, Sven Höfling, Lukas Worschech

Physics Faculty Publications

We have investigated photodetectors based on an AlGaAs/GaAs double barrier structure with a nearby lattice-matched GaInNAs absorption layer. Photons with the telecommunication wavelength λ = 1.3 µm lead to hole accumulation close to the double barrier inducing a voltage shift ΔV(V) of the current-voltage curve, which depends strongly on the bias voltage V. A model is proposed describing ΔV(V) and the photocurrent response in excellent agreement with the experimental observations. According to the model, an interplay of the resonant tunneling diode (RTD) quantum efficiency ƞ(V), the lifetime of photogenerated and accumulated charge carriers τ ...


Mechanisms Of Hemolysis-Associated Platelet Activation, Christine C. Helms, M. Marvel, W. Zhao, M. Stahle, R. Vest, G. J. Kato, J. S. Lee, G. Christ, M. T. Gladwin, R. R. Hantgan, D. B. Kim-Shapiro Dec 2013

Mechanisms Of Hemolysis-Associated Platelet Activation, Christine C. Helms, M. Marvel, W. Zhao, M. Stahle, R. Vest, G. J. Kato, J. S. Lee, G. Christ, M. T. Gladwin, R. R. Hantgan, D. B. Kim-Shapiro

Physics Faculty Publications

Background

Intravascular hemolysis occurs after blood transfusion, in hemolytic anemias, and in other conditions, and is associated with hypercoagulable states. Hemolysis has been shown to potently activate platelets in vitro and in vivo, and several mechanisms have been suggested to account for this, including: (i) direct activation by hemoglobin (Hb); (ii) increase in reactive oxygen species (ROS); (iii) scavenging of nitric oxide (NO) by released Hb; and (iv) release of intraerythrocytic ADP.

Objective

To elucidate the mechanism of hemolysis-mediated platelet activation.

Methods

We used flow cytometry to detect PAC-1 binding to activated platelets for in vitro experiments, and a Siemens ...


Remnants Of Spherical Shell Structures In Deformed Nuclei: The Impact Of An N = 64 Neutron Subshell Closure On The Structure Of N ≈ 90 Gadolinium Nuclei, T. J. Ross, R. O. Hughes, C. W. Beausang, J. M. Allmond, C. Angell, M. S. Basunia, D. L. Bleuel, J. T. Burke, R. J. Casperson, J. Escher, P. Fallon, R. Hatarik, J. Munson, S. Paschalis, M. Petri, L. Phair, J. J. Ressler, N. D. Scielzo Sep 2013

Remnants Of Spherical Shell Structures In Deformed Nuclei: The Impact Of An N = 64 Neutron Subshell Closure On The Structure Of N ≈ 90 Gadolinium Nuclei, T. J. Ross, R. O. Hughes, C. W. Beausang, J. M. Allmond, C. Angell, M. S. Basunia, D. L. Bleuel, J. T. Burke, R. J. Casperson, J. Escher, P. Fallon, R. Hatarik, J. Munson, S. Paschalis, M. Petri, L. Phair, J. J. Ressler, N. D. Scielzo

Physics Faculty Publications

Odd-mass gadolinium isotopes around N = 90 were populated by the (p,d) reaction, utilizing 25-MeV protons, resulting in population of low-spin quasineutron states at energies near and below the Fermi surface. Systematics of the single quasineutron levels populated are presented. A large excitation energy gap is observed between levels originating from the 2d3/2, 1h11/2, and 3s1/2 spherical parents (above the N = 64 gap), and the 2d5/2 (below the gap), indicating that the spherical shell model level spacing is maintained at least to moderate deformations.


Hemoglobin-Mediated Nitric Oxide Signaling, Christine C. Helms, D. B. Kim-Shapiro Aug 2013

Hemoglobin-Mediated Nitric Oxide Signaling, Christine C. Helms, D. B. Kim-Shapiro

Physics Faculty Publications

The rate that hemoglobin reacts with nitric oxide (NO) is limited by how fast NO can diffuse into the heme pocket. The reaction is as fast as any ligand/protein reaction can be and the result, when hemoglobin is in its oxygenated form, is formation of nitrate in what is known as the dioxygenation reaction. As nitrate, at the concentrations made through the deoxygenation reaction, is biologically inert, the only role hemoglobin was once thought to play in NO signaling was to inhibit it. However, there are now several mechanisms that have been discovered by which hemoglobin may preserve, control ...


Systematic Effects In Interferometric Observations Of The Cosmic Microwave Background Polarization, Ata Karakci, Le Zhang, P. M. Sutter, Emory F. Bunn, Andrei Korotkov, Peter Timbie, Gregory S. Tucker, Benjamin D. Wandelt Jul 2013

Systematic Effects In Interferometric Observations Of The Cosmic Microwave Background Polarization, Ata Karakci, Le Zhang, P. M. Sutter, Emory F. Bunn, Andrei Korotkov, Peter Timbie, Gregory S. Tucker, Benjamin D. Wandelt

Physics Faculty Publications

The detection of the primordial B-mode spectrum of the polarized cosmic microwave background (CMB) signal may provide a probe of inflation. However, observation of such a faint signal requires excellent control of systematic errors. Interferometry proves to be a promising approach for overcoming such a challenge. In this paper we present a complete simulation pipeline of interferometric observations of CMB polarization, including systematic errors. We employ two different methods for obtaining the power spectra from mock data produced by simulated observations: the maximum likelihood method and the method of Gibbs sampling. We show that the results from both methods ...


Quadrupole Collectivity In Neutron-Rich Fe And Cr Isotopes, H. L. Crawford, R. M. Clark, P. Fallon, A. O. Macchiavelli, T. Baugher, D. Bazin, C. W. Beausang, J. S. Berryman, D. L. Bleuel, C. M. Campbell, M. Cromaz, G. De Angelis, A. Gade, R. O. Hughes, I. Y. Lee, S. M. Lenzi, F. Nowacki, S. Paschalis, M. Petri, A. Poves, A. Ratkiewicz, T. J. Ross, E. Sahin, D. Weisshaar, K. Wimmer, R. Winkler Jun 2013

Quadrupole Collectivity In Neutron-Rich Fe And Cr Isotopes, H. L. Crawford, R. M. Clark, P. Fallon, A. O. Macchiavelli, T. Baugher, D. Bazin, C. W. Beausang, J. S. Berryman, D. L. Bleuel, C. M. Campbell, M. Cromaz, G. De Angelis, A. Gade, R. O. Hughes, I. Y. Lee, S. M. Lenzi, F. Nowacki, S. Paschalis, M. Petri, A. Poves, A. Ratkiewicz, T. J. Ross, E. Sahin, D. Weisshaar, K. Wimmer, R. Winkler

Physics Faculty Publications

Intermediate-energy Coulomb excitation measurements are performed on the N≥40 neutron-rich nuclei 66, 68Fe and 64Cr. The reduced transition matrix elements providing a direct measure of the quadrupole collectivity B(E2; 2+1→ 0+1) are determined for the first time in 68Fe42 and 64Cr40 and confirm a previous recoil distance method lifetime measurement in 66Fe40. The results are compared to state-of-the-art large-scale shell-model calculations within the full fpgd neutron orbital model space using the Lenzi-Nowacki-Poves-Sieja effective interaction and confirm the results of the calculations that show these nuclei are well ...


Maximum Likelihood Analysis Of Systematic Errors In Interferometric Observations Of The Cosmic Microwave Background, Le Zhang, Ata Karakci, Paul M. Sutter, Emory F. Bunn, Andrei Korotkov, Peter Timbie, Gregory S. Tucker, Benjamin D. Wandelt Jun 2013

Maximum Likelihood Analysis Of Systematic Errors In Interferometric Observations Of The Cosmic Microwave Background, Le Zhang, Ata Karakci, Paul M. Sutter, Emory F. Bunn, Andrei Korotkov, Peter Timbie, Gregory S. Tucker, Benjamin D. Wandelt

Physics Faculty Publications

We investigate the impact of instrumental systematic errors in interferometric measurements of the cosmic microwave background (CMB) temperature and polarization power spectra. We simulate interferometric CMB observations to generate mock visibilities and estimate power spectra using the statistically optimal maximum likelihood technique. We define a quadratic error measure to determine allowable levels of systematic error that does not induce power spectrum errors beyond a given tolerance. As an example, in this study we focus on differential pointing errors. The effects of other systematics can be simulated by this pipeline in a straightforward manner. We find that, in order to accurately ...


Electron Transport In Quantum Dot Chains: Dimensionality Effects And Hopping Conductance, V. P. Kunets, Mariama Rebello Sousa Dias, T. Rembert, M. E. Ware, Y. I. Mazur, V. Lopez-Richard, H. A. Mantooth, G. E. Marques, G. J. Salamo May 2013

Electron Transport In Quantum Dot Chains: Dimensionality Effects And Hopping Conductance, V. P. Kunets, Mariama Rebello Sousa Dias, T. Rembert, M. E. Ware, Y. I. Mazur, V. Lopez-Richard, H. A. Mantooth, G. E. Marques, G. J. Salamo

Physics Faculty Publications

Detailed experimental and theoretical studies of lateral electron transport in a system of quantum dot chains demonstrate the complicated character of the conductance within the chain structure due to the interaction of conduction channels with different dimensionalities. The one-dimensional character of states in the wetting layer results in an anisotropic mobility, while the presence of the zero-dimensional states of the quantum dots leads to enhanced hopping conductance, which affects the low-temperature mobility and demonstrates an anisotropy in the conductance. These phenomena were probed by considering a one-dimensional model of hopping along with band filling effects. Differences between the model and ...