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Selected Works

2004

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Articles 1 - 30 of 44

Full-Text Articles in Physics

Non-Bps Brane Dynamics And Dual Tensor Gauge Theory, T Clark, M Nitta, Tonnis Ter Veldhuis Dec 2004

Non-Bps Brane Dynamics And Dual Tensor Gauge Theory, T Clark, M Nitta, Tonnis Ter Veldhuis

Tonnis ter Veldhuis

No abstract provided.


Low Background Techniques For The Borexino Nylon Vessels, Andrea Pocar Nov 2004

Low Background Techniques For The Borexino Nylon Vessels, Andrea Pocar

Andrea Pocar

Borexino is an organic liquid scintillator underground detector for low energy solar neutrinos. The experiment has to satisfy extremely stringent low background requirements. The thin nylon spherical scintillator containment vessel has to meet cleanliness and low radioactivity levels second only, within the detector, to the scintillator itself. Overall, the background from the vessel in the fiducial volume of the detector must be kept at the level of one event per day or better. The requirements, design choices, results from laboratory tests, and fabrication techniques that have been adopted to meet this goal are presented. Details of the precautions taken during ...


Application Of Detuned Laser Beatwave For Generation Of Few-Cycle Electromagnetic Pulses, Serguei Y. Kalmykov, Gennady Shvets Nov 2004

Application Of Detuned Laser Beatwave For Generation Of Few-Cycle Electromagnetic Pulses, Serguei Y. Kalmykov, Gennady Shvets

Serge Youri Kalmykov

An approach to compressing high-power laser beams in plasmas via coherent Raman sideband generation is described. The technique requires two beams: a pump and a probe detuned by a near-resonant frequency \Omega < \omega_p. The two laser beams drive a high-amplitude electron plasma wave (EPW) which modifies the refractive index of plasma so as to produce a periodic phase modulation of the incident laser with the laser beat period t_b = 2\pi / \Omega. After propagation through plasma, the original laser beam breaks into a train of chirped beatnotes (each of duration t_b). The chirp is positive (the longer-wavelength sidebands are advanced in time) when \Omega < \omega_p and negative otherwise. Finite group velocity dispersion (GVD) of radiation in plasma can compress the positively chirped beatnotes to a few-laser-cycle duration thus creating in plasma a sequence of sharp electromagnetic spikes separated in time by t_b. Driven EPW strongly couples the laser sidebands and thus reduces the effect of GVD. Compression of the chirped beatnotes can be implemented in a separate plasma of higher density, where the laser sidebands become uncoupled.


Field-And Temperature-Induced Topological Phase Transitions In Three Dimensional N-Component London Superconductor, J. Smiseth, E. Smorgrav, Egor Babaev, A. Sudbo Nov 2004

Field-And Temperature-Induced Topological Phase Transitions In Three Dimensional N-Component London Superconductor, J. Smiseth, E. Smorgrav, Egor Babaev, A. Sudbo

Egor Babaev

The phase diagram and critical properties of the $N$-component London superconductor are studied both analytically and through large-scale Monte-Carlo simulations in $d=2+1$ dimensions (components here refer to different replicas of the complex scalar field). Examples are given of physical systems to which this model is applicable. The model with different bare phase stiffnesses for each component, is a model of superconductivity which should arise out of metallic phases of light atoms under extreme pressure. A projected mixture of electronic and protonic condensates in liquid metallic hydrogen under extreme pressure is the simplest example, corresponding to N=2 ...


Non-Bps Brane Dynamics And Duality, T Clark, Muneto Nitta, Tonnis Ter Veldhuis Nov 2004

Non-Bps Brane Dynamics And Duality, T Clark, Muneto Nitta, Tonnis Ter Veldhuis

Tonnis ter Veldhuis

No abstract provided.


Modeling Correlated Main-Chain Motions In Proteins For Flexible Molecular Recognition., Maria Zavodsky, Ming Lei, M. Thorpe, Anthony Day, Leslie Kuhn Oct 2004

Modeling Correlated Main-Chain Motions In Proteins For Flexible Molecular Recognition., Maria Zavodsky, Ming Lei, M. Thorpe, Anthony Day, Leslie Kuhn

Anthony Roy Day

We describe a new method for modeling protein and ligand main-chain flexibility, and show its ability to model flexible molecular recognition. The goal is to sample the full conformational space, including large-scale motions that typically cannot be reached in molecular dynamics simulations due to the computational intensity, as well as conformations that have not been observed yet by crystallography or NMR. A secondary goal is to assess the degree of flexibility consistent with protein–ligand recognition. Flexibility analysis of the target protein is performed using the graph-theoretic algorithm FIRST, which also identifies coupled networks of covalent and noncovalent bonds within ...


Simulation Of High Intensity Laser Pulse Propagation Through Optical Systems, Jeremy Gulley, Erik Zeek, William Dennis Sep 2004

Simulation Of High Intensity Laser Pulse Propagation Through Optical Systems, Jeremy Gulley, Erik Zeek, William Dennis

Jeremy R. Gulley

No abstract is currently available.


Asymptotic Accuracy Of Geoacoustic Inversions, Michele Zanolin, Ian Ingram, Aaron Thode, Nicholas C. Makris Sep 2004

Asymptotic Accuracy Of Geoacoustic Inversions, Michele Zanolin, Ian Ingram, Aaron Thode, Nicholas C. Makris

Michele Zanolin

Criteria necessary to accurately estimate a set of unknown geoacoustic parameters from remote acoustic measurements are developed in order to aid the design of geoacoustic experiments. The approach is to have estimation error fall within a specified design threshold by adjusting controllable quantities such as experimental sample size or signal-to-noise ratio (SNR). This is done by computing conditions on sample size and SNR necessary for any estimate to have a variance that (1) asymptotically attains the Cramer–Rao lower bound (CRLB) and (2) has a CRLB that falls within the specified design error threshold. Applications to narrow band deterministic signals ...


Stimulated Raman Backscattering Of Laser Radiation In Deep Plasma Channels, Serguei Y. Kalmykov, Gennady Shvets Sep 2004

Stimulated Raman Backscattering Of Laser Radiation In Deep Plasma Channels, Serguei Y. Kalmykov, Gennady Shvets

Serge Youri Kalmykov

Stimulated Raman backscattering (RBS) of intense laser radiation confined by a single-mode plasma channel with a radial variation of plasma frequency greater than a homogeneous-plasma RBS bandwidth is characterized by a strong transverse localization of resonantly driven electron plasma waves (EPW). The EPW localization reduces the peak growth rate of RBS and increases the amplification bandwidth. The continuum of nonbound modes of backscattered radiation shrinks the transverse field profile in a channel and increases the RBS growth rate. Solution of the initial-value problem shows that an electromagnetic pulse amplified by the RBS in the single-mode deep plasma channel has a ...


Amplification Of Electrostatic Ion-Cyclotron Waves In A Plasma With Magnetic-Field-Aligned Ion Flow Shear And No Electric Current, Erick Agrimson Aug 2004

Amplification Of Electrostatic Ion-Cyclotron Waves In A Plasma With Magnetic-Field-Aligned Ion Flow Shear And No Electric Current, Erick Agrimson

Erick Agrimson

No abstract provided.


Ester Type Banana-Shaped Liquid Crystalline Monomers: Synthesis And Physical Properties, Katalin Fodor-Csorba, Aniko Vajda, Antal Jakli, Christian Slugovc, Gregor Trimmel, Dietrich Demus, Eszter Gacz-Baitz, Sandor Holly, Giancarlo Galli Jun 2004

Ester Type Banana-Shaped Liquid Crystalline Monomers: Synthesis And Physical Properties, Katalin Fodor-Csorba, Aniko Vajda, Antal Jakli, Christian Slugovc, Gregor Trimmel, Dietrich Demus, Eszter Gacz-Baitz, Sandor Holly, Giancarlo Galli

Antal Jakli

New ester-type banana (bent-shaped) monomers, 1,3-phenylene bis[4'-(alken-1-yloxy)-biphenyl-4-carboxylate] s Ia - Vb, with different substituent(s) on the central phenyl ring (H, CH3, Cl or NO2) and alkenyl tails in the side arms ( decenyl or undecenyl) were prepared. The analogues IIIa - IVb with 4-chloro- or 4,6-dichloro-substituents exhibited a nematic phase, while Va, Vb with 2-nitro-substituent showed a B-7 phase at relatively low temperature. All the compounds were stable, no degradation or polymerization was observed under applied electric fields or heat treatments. Electro-hydrodynamic instabilities were observed in the nematic phase of each sample. In the B-7 phase of ...


Extended Tidal Structure In Two Lyalpha-Emitting Starburst Galaxies, John M. Cannon, E D. Skillman, D Kunth, C Leitherer, M Mas-Hesse, G Östlin, A Petrosian Jun 2004

Extended Tidal Structure In Two Lyalpha-Emitting Starburst Galaxies, John M. Cannon, E D. Skillman, D Kunth, C Leitherer, M Mas-Hesse, G Östlin, A Petrosian

John Cannon

No abstract provided.


A Dunking Bird Of The Second Kind, Nadine Abraham, Peter Palffy-Muhoray May 2004

A Dunking Bird Of The Second Kind, Nadine Abraham, Peter Palffy-Muhoray

Peter Palffy-Muhoray

The conventional dunking bird is a heat engine that relies on the temperature difference between the head and the tail of the bird for its operation. We describe a new type of dunking bird that is not a heat engine, but one that directly uses the chemical potential difference between liquid water and its vapor.


The Complex Neutral Gas Dynamics Of The Dwarf Starburst Galaxy Ngc 625, John M. Cannon, Naomi M. Mcclure-Griffiths, Evan D. Skillman, Stephanie Cote May 2004

The Complex Neutral Gas Dynamics Of The Dwarf Starburst Galaxy Ngc 625, John M. Cannon, Naomi M. Mcclure-Griffiths, Evan D. Skillman, Stephanie Cote

John Cannon

No abstract provided.


Lattice Thermal Conductivity Of K2(Bi1_Zsbz)8se13 Solid Solutions, Jeffrey S. Dyck, Theodora Kyratsi, Evripides Hatzikraniotis, M Paraskevopoulous, H. K. Shin, Ctirad Uher, Mercouri Kanatzidis Apr 2004

Lattice Thermal Conductivity Of K2(Bi1_Zsbz)8se13 Solid Solutions, Jeffrey S. Dyck, Theodora Kyratsi, Evripides Hatzikraniotis, M Paraskevopoulous, H. K. Shin, Ctirad Uher, Mercouri Kanatzidis

Jeffrey Dyck

The family of solid solutions of the type B -K2(Bi1_zSbz)8Se13 (0


Liquid Crystal Blazed Gratings Formed In A Single-Step Through Photo-Induced Localization Of Polymer Into A Prismatic Structure, Sang Hwa Kim, Liang-Chy Chien Apr 2004

Liquid Crystal Blazed Gratings Formed In A Single-Step Through Photo-Induced Localization Of Polymer Into A Prismatic Structure, Sang Hwa Kim, Liang-Chy Chien

Sang Kim

A liquid crystal blazed grating having a prismatic polymer microstructure has been developed. The polymer structure is fabricated by photo-induced localization and polymerization of a small concentration of monomer onto one substrate of an electro-optical cell by using ultraviolet light irradiation at 45degrees direction from normal incident. Using this method a periodical one-dimensional pattern with a prismatic shape of polymer can be formed on a one-dimensional pattern-forming state of a cholesteric host. The optical diffraction properties of the grating are evaluated by the application of electric field and light incident angles.


Liquid Crystal Blazed Gratings Formed In A Single-Step Through Photo-Induced Localization Of Polymer Into A Prismatic Structure, Sang Hwa Kim, Liang-Chy Chien Apr 2004

Liquid Crystal Blazed Gratings Formed In A Single-Step Through Photo-Induced Localization Of Polymer Into A Prismatic Structure, Sang Hwa Kim, Liang-Chy Chien

Liang-Chy Chien

A liquid crystal blazed grating having a prismatic polymer microstructure has been developed. The polymer structure is fabricated by photo-induced localization and polymerization of a small concentration of monomer onto one substrate of an electro-optical cell by using ultraviolet light irradiation at 45degrees direction from normal incident. Using this method a periodical one-dimensional pattern with a prismatic shape of polymer can be formed on a one-dimensional pattern-forming state of a cholesteric host. The optical diffraction properties of the grating are evaluated by the application of electric field and light incident angles.


Conduction Band Splitting And Transport Properties Of Bi2se3., J. Navrátil, J. Horák, T. Plecháček, S. Kamba, P. LošŤÁK, Jeffrey Dyck, W. Chen, C. Uher Mar 2004

Conduction Band Splitting And Transport Properties Of Bi2se3., J. Navrátil, J. Horák, T. Plecháček, S. Kamba, P. LošŤÁK, Jeffrey Dyck, W. Chen, C. Uher

Jeffrey Dyck

Detailed transport studies of single crystals of Bi2Se3 were made in the temperature range of 2–300K, and the data were analyzed in terms of a model consisting of two groups of electrons—a centrosymmetrical lower conduction band and an upper conduction band located away from the Γ-point. Very good agreement with the experimental data is obtained assuming the electrons are scattered on acoustic phonons and ionized impurities. A rather strong influence of the latter mechanism is attributed to a large number of charged selenium vacancies in Bi2Se3. The fitted transport parameters were used to calculate the electronic portion of ...


Infrared Laser Spectroscopy Of Jet Cooled Cobalt Tricarbonyl, Kyle Trauth, William A. Burns, Ginger Berry, Scott Reeve Feb 2004

Infrared Laser Spectroscopy Of Jet Cooled Cobalt Tricarbonyl, Kyle Trauth, William A. Burns, Ginger Berry, Scott Reeve

Scott Reeve

No abstract provided.


Infrared Depletion Spectroscopy Of Aniline–Toluene Cluster: The Investigation Of The Red Shifts Of The Nh2 Stretching Vibrations Of Aniline–Aromatic Clusters, Naveed Piracha, F. Ito, T. Nakanaga Feb 2004

Infrared Depletion Spectroscopy Of Aniline–Toluene Cluster: The Investigation Of The Red Shifts Of The Nh2 Stretching Vibrations Of Aniline–Aromatic Clusters, Naveed Piracha, F. Ito, T. Nakanaga

Naveed K. Piracha

The infrared spectra of the NH2 stretching vibrations of aniline–toluene cluster and corresponding cluster cation have been measured by the infrared depletion method. The NH2 stretching vibrations of aniline–toluene cluster were observed at 3393 and 3468 cm−1. The red shifts from the corresponding bands of aniline monomer are 29 and 40 cm−1, respectively, for the NH2 symmetric and anti-symmetric stretching vibrations. The magnitudes of the red shifts are similar to those of other aniline–aromatic clusters. The structure of this cluster has been found to be a sandwich type, that is, the two aromatic rings are ...


Effective Action For Brane Localized Gauge Fields, T Clark, Muneto Nitta, Tonnis Ter Veldhuis Feb 2004

Effective Action For Brane Localized Gauge Fields, T Clark, Muneto Nitta, Tonnis Ter Veldhuis

Tonnis ter Veldhuis

No abstract provided.


Cubic : Bulk Thermoelectric Materials With High Figure Of Merit, Kuei Hsu, Sim Loo, Fu Guo, Wei Chen, Jeffrey Dyck, Cterid Uher, Tim Hogan, E. Polychroniadis, Mercouri Kanatzidis Feb 2004

Cubic : Bulk Thermoelectric Materials With High Figure Of Merit, Kuei Hsu, Sim Loo, Fu Guo, Wei Chen, Jeffrey Dyck, Cterid Uher, Tim Hogan, E. Polychroniadis, Mercouri Kanatzidis

Jeffrey Dyck

The conversion of heat to electricity by thermoelectric devices may play a key role in the future for energy production and utilization. However, in order to meet that role, more efficient thermoelectric materials are needed that are suitable for high-temperature applications. We show that the material system may be suitable for this purpose. With m = 10 and 18 and doped appropriately, n-type semiconductors can be produced that exhibit a high thermoelectric figure of merit of ~2.2 at 800 kelvin. In the temperature range 600 to 900 kelvin, the material is expected to outperform all reported bulk thermoelectrics, thereby earmarking ...


Effect Of Measurement On The Periodicity Of The Coulomb Staircase Of A Superconducting Box, Jaan Männik, J. E. Lukens Jan 2004

Effect Of Measurement On The Periodicity Of The Coulomb Staircase Of A Superconducting Box, Jaan Männik, J. E. Lukens

Jaan Männik

We report on the effect of the backaction of a single Cooper pair transistor electrometer (E) on the charge state of a superconducting box (B). The charge is e periodic in the gate bias of B when E is operated near voltages 2Δ/e or 4Δ/e. We show that this is due to quasiparticle poisoning of B at a rate proportional to the number of quasiparticle tunneling events in E per second. We are able to eliminate this backaction and recover 2e-charge periodicity using a new measurement method based on switching-current modulation of E.

URL: http://link.aps.org ...


Hypothetical Thermodynamic Properties: The Boiling And Critical Temperatures Of Polyethylene And Polytetrafluoroethylene, James S. Chickos Jan 2004

Hypothetical Thermodynamic Properties: The Boiling And Critical Temperatures Of Polyethylene And Polytetrafluoroethylene, James S. Chickos

James Chickos

No abstract provided.


Synthesis, Crystal Structure And Thermoelectric Properties Of Β-K2bi8se13 Solid Solutions, Theodora Kyratsi, Duck-Young Chung, Jeff Dyck, Ctirad Uher, Sangeeta Lal, Sim Loo, Tim Hogan, John Ireland, Carl Kannewurf, Evripides Hatzikraniotis, Konstantinos Paraskevopoulos, Mercouri Kanatzidis Dec 2003

Synthesis, Crystal Structure And Thermoelectric Properties Of Β-K2bi8se13 Solid Solutions, Theodora Kyratsi, Duck-Young Chung, Jeff Dyck, Ctirad Uher, Sangeeta Lal, Sim Loo, Tim Hogan, John Ireland, Carl Kannewurf, Evripides Hatzikraniotis, Konstantinos Paraskevopoulos, Mercouri Kanatzidis

Jeffrey Dyck

Solid solution series of the type K2Bi8-xSbxSe13, K2-xRbxBi8Se13 as well as K2Bi8Se13-xSx were prepared and the distribution of the atoms (Bi/Sb, K/Rb and Se/S) on different crystallographic sites, the band gaps and their thermoelectric properties were studied. The distribution Se/S appears to be more uniform than the distribution of the Sb and Rb atoms in the β-K2Bi8Se13 structure that shows preference in specific sites in the lattice. Band gap is mainly affected by Sb and S substitution. Seebeck coefficient measurements showed n-type character for of all Se/S members. In the Bi/Sb series an enhancement ...


Pollution Flushing Models In Stella, Stephen Mecca, Christopher Severino Dec 2003

Pollution Flushing Models In Stella, Stephen Mecca, Christopher Severino

Stephen J. Mecca

Pollution flushing of tidal harbors has been elegantly modeled using analytical techniques for conditions that enable direct integration of the relevant equations during the flood and ebb tidal cycles [1]. Such analytical techniques, though limited to simple pollution loading and geometric conditions, give excellent agreement with physical models run under similar conditions and, hence, provide a yardstick against which alternative numerical formulations may be judged. The present work develops a Stella model, which replicates the results of the analytical approach and offers several features that extend the utility of the basic tidal prism model. These additional features include the ability ...


Quantum Mysteries Revisited Again, Padmanabhan Aravind Dec 2003

Quantum Mysteries Revisited Again, Padmanabhan Aravind

Padmanabhan K. Aravind

This paper describes a device, consisting of a central source and two widely separated detectors with six switch settings each, that provides a simple gedanken demonstration of the non-classical correlations that are the subject of Bell’s theorem without relying on either statistical effects or the occurrence of rare events. The mechanism underlying the operation of the device is revealed for readers with a knowledge of quantum mechanics.


Microwave Thawing Of Cylinders., Tim Marchant Dec 2003

Microwave Thawing Of Cylinders., Tim Marchant

Tim Marchant

Microwave thawing of a cylinder is examined. The electromagnetic field is governed by Maxwell's equations, where the electrical conductivity and the thermal absorptivity are both assumed to depend on temperature. The forced heat equation governs the absorption and diffusion of heat where convective heating occurs at the surface of the cylinder, while the Stefan condition governs the position of the moving phase boundary. A semi-analytical model, which consists of ordinary differential equations, is developed using the Galerkin method. Semi-analytical solutions are found for the temperature, the electric-field amplitude in the cylinder and the position of the moving boundary. Two ...


Deep Tissue Imaging Approaches By Direct Capture Of Two-Photon Absorptionmacro To Nano, T. Ye, W. Wagner, Peifang Tian, G. Yurtsever, M. Fischer, W. Wagner Dec 2003

Deep Tissue Imaging Approaches By Direct Capture Of Two-Photon Absorptionmacro To Nano, T. Ye, W. Wagner, Peifang Tian, G. Yurtsever, M. Fischer, W. Wagner

Peifang Tian

No abstract provided.


Asymptotic Solitons For A Third-Order Kortweg-De Vries Equation, Tim Marchant Dec 2003

Asymptotic Solitons For A Third-Order Kortweg-De Vries Equation, Tim Marchant

Tim Marchant

Solitary wave interaction for a higher-order version of the Korteweg–de Vries (KdV) equation is considered. The equation is obtained by retaining third-order terms in the perturbation expansion, where for the KdV equation only first-order terms are retained. The third-order KdV equation can be asymptotically transformed to the KdV equation, if the third-order coefficients satisfy a certain algebraic relationship. The third-order two-soliton solution is derived using the transformation. The third-order phase shift corrections are found and it is shown that the collision is asymptotically elastic. The interaction of two third-order solitary waves is also considered numerically. Examples of an elastic ...