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Selected Works

2011

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Articles 1 - 30 of 579

Full-Text Articles in Physics

Determining Magnetic Nanoparticle Size Distributions From Thermomagnetic Measurements, R. Dipietro, H. Johnson, S. Bennett, T. Nummy, L. Lewis, D. Heiman Dec 2011

Determining Magnetic Nanoparticle Size Distributions From Thermomagnetic Measurements, R. Dipietro, H. Johnson, S. Bennett, T. Nummy, L. Lewis, D. Heiman

Laura H. Lewis

Thermomagnetic measurements are used to obtain the size distribution and anisotropy of magnetic nanoparticles. An analytical transformation method is described which utilizes temperature-dependent zero-field cooling (ZFC) magnetization data to provide a quantitative measurement of the average diameter and relative abundance of superparamagnetic nanoparticles. Applying this method to self-assembled MnAs nanoparticles in MnAs-GaAs composite films reveals a log-normal size distribution and reduced anisotropy for nanoparticles compared to bulk materials. This analytical technique holds promise for rapid assessment of the size distribution of an ensemble of superparamagnetic nanoparticles.


Determining Magnetic Nanoparticle Size Distributions From Thermomagnetic Measurements., R. S. Dipietro, H. G. Johnson, S. P. Bennett, T. J. Nummy, L. H. Lewis, D. Heiman Dec 2011

Determining Magnetic Nanoparticle Size Distributions From Thermomagnetic Measurements., R. S. Dipietro, H. G. Johnson, S. P. Bennett, T. J. Nummy, L. H. Lewis, D. Heiman

Laura H. Lewis

Thermomagnetic measurements are used to obtain the size distribution and anisotropy of magnetic nanoparticles. An analytical transformation method is described which utilizes temperature-dependent zero-field cooling magnetization data to provide a quantitative measurement of the average diameter and relative abundance of superparamagnetic nanoparticles. Applying this method to self-assembled MnAs nanoparticles in MnAs–GaAs composite films reveals a log-normal size distribution and reduced anisotropy for nanoparticles compared to bulk materials. This analytical technique holds promise for rapid assessment of the size distribution of an ensemble of superparamagnetic nanoparticles.


Magnetic Signature Of Symmetry Reduction In Epitaxial La₀.₆₇Sr₀.₃₃Mno₃ Films, Radhika Barua, L. Lewis, D. Heiman Dec 2011

Magnetic Signature Of Symmetry Reduction In Epitaxial La₀.₆₇Sr₀.₃₃Mno₃ Films, Radhika Barua, L. Lewis, D. Heiman

Laura H. Lewis

The magnetic properties of epitaxially grown La0.67Sr0.33MnO3 perovskite thin films were investigated to elucidate an unexpected broken symmetry between orthogonal [100] and [010] inplane directions, resulting from the magnetostructural coupling between the film and the cubic SrTiO3 (001) substrate. The films were synthesized by molecular beam epitaxy with either complete or zero A-site cation disorder. Magnetization measured in [100] and [010] directions shows differences that signal a reduction of the in-plane cubic symmetry only for T < 290 K. The magnetization asymmetry is more robust in the film with complete A-site disorder. These results are attributed to a dominant ...


Universal Properties Of Linear Magnetoresistance In Strongly Disordered Mnas-Gaas Composite Semiconductors, H. G. Johnson, S. P. Bennett, R. Barua, L. H. Lewis, D. Heiman Dec 2011

Universal Properties Of Linear Magnetoresistance In Strongly Disordered Mnas-Gaas Composite Semiconductors, H. G. Johnson, S. P. Bennett, R. Barua, L. H. Lewis, D. Heiman

Laura H. Lewis

Linear magnetoresistance (LMR) occurs in semiconductors as a consequence of strong electrical disorder and is characterized by nonsaturating magnetoresistance that is proportional to the applied magnetic field. By investigating a disordered MnAs-GaAs composite material, it is found that the magnitude of the LMR is numerically equal to the carrier mobility over a wide range and is independent of carrier density. This behavior is complementary to the Hall effect that is independent of the mobility and dependent on the carrier density. Moreover, the LMR appears to be insensitive to the details of the disorder and points to a universal explanation of ...


Determining Magnetic Nanoparticle Size Distributions From Thermomagnetic Measurements., R. S. Dipietro, H. G. Johnson, S. P. Bennett, T. J. Nummy, L. H. Lewis, D. Heiman Dec 2011

Determining Magnetic Nanoparticle Size Distributions From Thermomagnetic Measurements., R. S. Dipietro, H. G. Johnson, S. P. Bennett, T. J. Nummy, L. H. Lewis, D. Heiman

Donald Heiman

Thermomagnetic measurements are used to obtain the size distribution and anisotropy of magnetic nanoparticles. An analytical transformation method is described which utilizes temperature-dependent zero-field cooling magnetization data to provide a quantitative measurement of the average diameter and relative abundance of superparamagnetic nanoparticles. Applying this method to self-assembled MnAs nanoparticles in MnAs–GaAs composite films reveals a log-normal size distribution and reduced anisotropy for nanoparticles compared to bulk materials. This analytical technique holds promise for rapid assessment of the size distribution of an ensemble of superparamagnetic nanoparticles.


Magnetotransport Properties Of Mn-Si-C Based Nanostructures, Sungmu Kang, Greg A. Brewer, Battogtokh Jugdersuren, Robert Dipietro, Don Heiman, Andrew C. Buechele, David A. Mckeown, Ian L. Pegg, John Philip Dec 2011

Magnetotransport Properties Of Mn-Si-C Based Nanostructures, Sungmu Kang, Greg A. Brewer, Battogtokh Jugdersuren, Robert Dipietro, Don Heiman, Andrew C. Buechele, David A. Mckeown, Ian L. Pegg, John Philip

Donald Heiman

Boron-incorporated Mn5SiC nanowires were grown using chemical vapor deposition method. The nanowire cluster exhibits magnetic hysteresis loops at room temperature and the strength of the magnetic behavior depends on the concentration of the boron incorporation. Mn5SiC nanowire-based devices exhibit spin dependent transport properties which shows significant changes with boron content. Large magnetoresistance is observed in lightly boron-incorporated nanowire devices and it decreases with increase in boron content.


Magnetic Signature Of Symmetry Reduction In Epitaxial La₀.₆₇Sr₀.₃₃Mno₃ Films, Radhika Barua, L. H. Lewis, D. Heiman Dec 2011

Magnetic Signature Of Symmetry Reduction In Epitaxial La₀.₆₇Sr₀.₃₃Mno₃ Films, Radhika Barua, L. H. Lewis, D. Heiman

Donald Heiman

The magnetic properties of epitaxially grown La0.67Sr0.33MnO3 perovskite thin films were investigated to elucidate an unexpected broken symmetry between orthogonal [100] and [010] inplane directions, resulting from the magnetostructural coupling between the film and the cubic SrTiO3 (001) substrate. The films were synthesized by molecular beam epitaxy with either complete or zero A-site cation disorder. Magnetization measured in [100] and [010] directions shows differences that signal a reduction of the in-plane cubic symmetry only for T < 290 K. The magnetization asymmetry is more robust in the film with complete A-site disorder. These results are attributed to a dominant ...


Universal Properties Of Linear Magnetoresistance In Strongly Disordered Mnas-Gaas Composite Semiconductors, H. Johnson, S. Bennett, R. Barua, L. Lewis, D. Heiman Dec 2011

Universal Properties Of Linear Magnetoresistance In Strongly Disordered Mnas-Gaas Composite Semiconductors, H. Johnson, S. Bennett, R. Barua, L. Lewis, D. Heiman

Donald Heiman

Linear magnetoresistance (LMR) occurs in semiconductors as a consequence of strong electrical disorder and is characterized by nonsaturating magnetoresistance that is proportional to the applied magnetic field. By investigating a disordered MnAs-GaAs composite material, it is found that the magnitude of the LMR is numerically equal to the carrier mobility over a wide range and is independent of carrier density. This behavior is complementary to the Hall effect that is independent of the mobility and dependent on the carrier density. Moreover, the LMR appears to be insensitive to the details of the disorder and points to a universal explanation of ...


Large Low Field Magnetoresistance In La₀.₆₇Sr₀.₃₃Mno₃ Nanowire Devices, Battogtokh Jugdersuren, Sungmu Kang, Robert S. Dipietro, Don Heiman, David Mckeown, Ian L. Pegg, John Philip Dec 2011

Large Low Field Magnetoresistance In La₀.₆₇Sr₀.₃₃Mno₃ Nanowire Devices, Battogtokh Jugdersuren, Sungmu Kang, Robert S. Dipietro, Don Heiman, David Mckeown, Ian L. Pegg, John Philip

Donald Heiman

Large low field magnetoresistance (LFMR) of about 28% is observed in La0.67Sr0.33MnO3 nanowires with 80 nm in diameter at T = 300 K. A gradual decrease in the LFMR has been found with increase in wire diameter. The LFMR drops to zero for wires above 280 nm in diameter. The nanowires are grown by means of electrospinning process and exhibit distorted orthorhombic crystal structure. The large LFMR is considered as a grain boundary effect as observed in several perovskite systems. The large LFMR observed in these manganites with reduced dimensions may be useful for room temperature device applications.


Large Coercivity In Nanostructured Rare-Earth-Free Mnxga Films, Don Heiman, Tom Nummy, Steve Bennett, Tom Cardinal Dec 2011

Large Coercivity In Nanostructured Rare-Earth-Free Mnxga Films, Don Heiman, Tom Nummy, Steve Bennett, Tom Cardinal

Donald Heiman

The magnetic hysteresis of MnxGa films exhibit remarkably large coercive fields as high as HC=2.5 T when fabricated with nanoscale particles of a suitable size and orientation. This coercivity is an order of magnitude larger than in well-ordered epitaxial film counterparts and bulk materials. The enhanced coercivity is attributed to the combination of large magnetocrystalline anisotropy and ~50-100 nm size nanoparticles. The large coercivity is also replicated in the electrical properties through the anomalous Hall effect. The magnitude of the coercivity approaches that found in rare-earth magnets, making them attractive for rare-earth-free magnet applications.


Ordering Of Glass Rods In Nematic And Cholesteric Liquid Crystals, A. T. Juhl, Deng-Ke Yang, V. P. Tondiglia, L. V. Natarajan, Timothy J. White, Timothy J. Bunning Nov 2011

Ordering Of Glass Rods In Nematic And Cholesteric Liquid Crystals, A. T. Juhl, Deng-Ke Yang, V. P. Tondiglia, L. V. Natarajan, Timothy J. White, Timothy J. Bunning

Deng-Ke Yang

The orientational assembly of glass rods (3 x similar to 15 mu m) in nematic, twisted nematic, and cholesteric liquid crystal cells was observed and quantified with optical microscopy. At this size, the rods were affected strongly by gravity and sedimented to the bottom of the cells. Temporal visualization of the sedimentation process (induced by flipping the cell over) shed insight into the effect the liquid crystal order had on the glass rod orientation. For nematic and twisted nematic geometries, the glass rods were aligned parallel to the local director orientation. Control experiments indicate that the rod alignment is not ...


Wiki Leaks Revelations In Global Context—The War Between ‘Right To Publish’ And ‘Ethical Code Of Conduct, Ratnesh Dwivedi Mr Nov 2011

Wiki Leaks Revelations In Global Context—The War Between ‘Right To Publish’ And ‘Ethical Code Of Conduct, Ratnesh Dwivedi Mr

Ratnesh Dwivedi

WikiLeaks is an international non-profit organisation that publishes submissions of private, secret, and classified media from anonymous news sources, news leaks, and whistleblowers. Its website, launched in 2006 under The Sunshine Press organisation claimed a database of more than 1.2 million documents within a year of its launch. WikiLeaks describes its founders as a mix of Chinese dissidents, journalists, mathematicians, and start-up company technologists from the United States, Taiwan, Europe, Australia, and South Africa. Julian Assange, an Australian Internet activist, is generally described as its director. The site was originally launched as a user-editable wiki, but has progressively moved ...


Thermodynamics And Phase Transitions For The Heisenberg Model On The Pinwheel Distorted Kagome Lattice, Ehsan Khatami, Rajiv R.P. Singh, Marcos Rigol Nov 2011

Thermodynamics And Phase Transitions For The Heisenberg Model On The Pinwheel Distorted Kagome Lattice, Ehsan Khatami, Rajiv R.P. Singh, Marcos Rigol

Ehsan Khatami

We study the Heisenberg model on the pinwheel distorted kagome lattice as observed in the material Rb2Cu3SnF12. Experimentally relevant thermodynamic properties at finite temperatures are computed utilizing numerical linked-cluster expansions. We also develop a Lanczos-based, zero-temperature, numerical linked-cluster expansion to study the approach of the pinwheel distorted lattice to the uniform kagome-lattice Heisenberg model. We find strong evidence for a phase transition before the uniform limit is reached, implying that the ground state of the kagome-lattice Heisenberg model is likely not pinwheel dimerized and is stable to finite pinwheel-dimerizing perturbations.


A Critical Study Of Organizational Communication And Organizational Communication Theories- A Historical Perspective, Ratnesh Dwivedi Mr Nov 2011

A Critical Study Of Organizational Communication And Organizational Communication Theories- A Historical Perspective, Ratnesh Dwivedi Mr

Ratnesh Dwivedi

Organizational Communication is the study that looks at human communication within and outside the organization. Conrad and Poole (1998) break the definition of organizational communication in parts, by first defining communication and then analyses the organization. These researchers define communication as “a process through which people, acting together, create, sustain, and manage meanings through the use of verbal and nonverbal signs and symbols within a particular context” (Conrad and Poole, 1998, p. 5). In the context of this book, Kenyans and their leaders are communicating their views and final decision through the ballot box to elect their third president, during ...


Public Accountability And Media : Its Success And Failure In Performing The Role As A Force For Public Accountability, Ratnesh Dwivedi Mr Nov 2011

Public Accountability And Media : Its Success And Failure In Performing The Role As A Force For Public Accountability, Ratnesh Dwivedi Mr

Ratnesh Dwivedi

Media accountability is a phrase that refers to the general (especially western) belief that mass media has to be accountable in the public’s interest - that is, they are expected to behave in certain ways that contribute to the public good. The concept is not clearly defined, and often collides with commercial interests of media owners; legal issues, such as the constitutional right to the freedom of the press in the U.S.; and governmental concerns about public security and order. Several international organizations, like International Freedom of Expression Exchange, Freedom House, International Press Institute, World Press Freedom Committee and ...


Application Of Asymptotic Expansions For Maximum Likelihood Estimators' Errors To Gravitational Waves From Inspiraling Binary Systems: The Network Case, Salvatore Vitale, Michele Zanolin Nov 2011

Application Of Asymptotic Expansions For Maximum Likelihood Estimators' Errors To Gravitational Waves From Inspiraling Binary Systems: The Network Case, Salvatore Vitale, Michele Zanolin

Michele Zanolin

This paper describes the most accurate analytical frequentist assessment to date of the uncertainties in the estimation of physical parameters from gravitational waves generated by nonspinning binary systems and Earth-based networks of laser interferometers. The paper quantifies how the accuracy in estimating the intrinsic parameters mostly depends on the network signal to noise ratio (SNR), but the resolution in the direction of arrival also strongly depends on the network geometry. We compare results for 6 different existing and possible global networks and two different choices of the parameter space. We show how the fraction of the sky where the one ...


Transport And Magnetic Critical Current In Superconducting Mgb2 Wires, J. Horvat, W. K. Yeoh, J. H. Kim, S. X. Dou Nov 2011

Transport And Magnetic Critical Current In Superconducting Mgb2 Wires, J. Horvat, W. K. Yeoh, J. H. Kim, S. X. Dou

Shi Xue Dou

Direct comparison of the magnetic and transport critical current density (Jc) for the same pieces of copper-sheathed MgB2 wires shows a large discrepancy in magnitude and field dependence of the two. The value of magnetic Jc can differ from the value of transport Jc by a factor of 10 or more. This discrepancy does not occur merely because of the difference in the voltage at which the magnetic and transport Jc are measured, but mainly because of the specific microstructure of MgB2. Such microstructure results in superconducting screening on at least two different length-scales, despite the absence of weak links ...


Peeling Adhesive Tape Emits Electromagnetic Radiation At Terahertz Frequencies, J. Horvat, R. A. Lewis Nov 2011

Peeling Adhesive Tape Emits Electromagnetic Radiation At Terahertz Frequencies, J. Horvat, R. A. Lewis

Roger A. Lewis

An unusual concept for a simple and inexpensive terahertz source is presented: unpeeling adhesive tape. The observed spectrum of this terahertz radiation exhibits a peak at 2 THz and a broader peak at 18 THz. The radiation is not polarized. The mechanism of terahertz radiation is tribocharging of the adhesive tape and subsequent discharge, possibly bremsstrahlung with absorption or energy density focusing during the dielectric breakdown of a gas. The accompanying optical emission is also a consequence of tribocharging.


Peeling Adhesive Tape Emits Electromagnetic Radiation At Terahertz Frequencies, J. Horvat, R. A. Lewis Nov 2011

Peeling Adhesive Tape Emits Electromagnetic Radiation At Terahertz Frequencies, J. Horvat, R. A. Lewis

Josip Horvat

An unusual concept for a simple and inexpensive terahertz source is presented: unpeeling adhesive tape. The observed spectrum of this terahertz radiation exhibits a peak at 2 THz and a broader peak at 18 THz. The radiation is not polarized. The mechanism of terahertz radiation is tribocharging of the adhesive tape and subsequent discharge, possibly bremsstrahlung with absorption or energy density focusing during the dielectric breakdown of a gas. The accompanying optical emission is also a consequence of tribocharging.


Photolithographic Surface Micromachining Of Polydimethylsiloxane (Pdms), Weiqiang Chen, Raymond H. W. Lam, Jianping Fu Nov 2011

Photolithographic Surface Micromachining Of Polydimethylsiloxane (Pdms), Weiqiang Chen, Raymond H. W. Lam, Jianping Fu

Weiqiang Chen

A major technical hurdle in microfluidics is the difficulty in achieving high fidelity lithographic patterning on polydimethylsiloxane (PDMS). Here, we report a simple yet highly precise and repeatable PDMS surface micromachining method using direct photolithography followed by reactive ion etching (RIE). Our method to achieve surface patterning of PDMS applied an O2 plasma treatment to PDMS to activate its surface to overcome the challenge of poor photoresist adhesion on PDMS for photolithography. Our photolithographic PDMS surface micromachining technique is compatible with conventional soft lithography techniques and other silicon-based surface and bulk micromachining methods. To illustrate the general application of our ...


Semitransparent Organic Solar Cells, F.R. Zhu Oct 2011

Semitransparent Organic Solar Cells, F.R. Zhu

Professor ZHU, Fu Rong

Compared to current silicon-based solar cells that are rigid, organic-based solar cells that use solution-based processing or low-cost non-vacuum deposition techniques are simpler and less expensive to manufacture. Organic photovoltaic cells can be made flexible, semitransparent and are light weight, offer more opportunities for application in new markets such as mobile electronics, disposable electronics, smart cards, digital applications, power generating windows, smart sensors, automotive, home appliances and outdoor lifestyle etc. Its unique flexibility and semi-transparency feature also adds a decorative and aesthetic dimension to the solar cells so that it can be used on curved and irregular surfaces – something that ...


Thermodynamics Of Strongly Interacting Fermions In Two-Dimensional Optical Lattices, Ehsan Khatami, Marcos Rigol Oct 2011

Thermodynamics Of Strongly Interacting Fermions In Two-Dimensional Optical Lattices, Ehsan Khatami, Marcos Rigol

Ehsan Khatami

We study finite-temperature properties of strongly correlated fermions in two-dimensional optical lattices by means of numerical linked cluster expansions, a computational technique that allows one to obtain exact results in the thermodynamic limit. We focus our analysis on the strongly interacting regime, where the on-site repulsion is of the order of or greater than the band width. We compute the equation of state, double occupancy, entropy, uniform susceptibility, and spin correlations for temperatures that are similar to or below the ones achieved in current optical lattice experiments. We provide a quantitative analysis of adiabatic cooling of trapped fermions in two ...


Physics Of Quasi-Monoenergetic Laser-Plasma Acceleration Of Electrons In The Blowout Regime, Serguei Y. Kalmykov, Bradley A. Shadwick, Arnaud Beck, Erik Lefebvre Oct 2011

Physics Of Quasi-Monoenergetic Laser-Plasma Acceleration Of Electrons In The Blowout Regime, Serguei Y. Kalmykov, Bradley A. Shadwick, Arnaud Beck, Erik Lefebvre

Serge Youri Kalmykov

No abstract provided.


Risk-Based Critical Infrastructure Priorities For Emp And Solar Storms, George H. Baker Iii Oct 2011

Risk-Based Critical Infrastructure Priorities For Emp And Solar Storms, George H. Baker Iii

George H Baker

Two electromagnetic phenomena have the potential to create continental-scale disasters. The first, nuclear electromagnetic pulse (EMP), results from a nuclear detonation high above the tropopause. The second, a major solar storm, or "solar tsunami" occurs naturally when an intense wave of charged particles from the sun perturbs the earth's magnetic field. Both phenomena can debilitate electrical and electronic systems necessary for the operation of infrastructure systems and services. One reason why a U.S. protection program has yet to be initiated is that policy makers continue to wrestle with the question of where to begin, given the Department of ...


Carbon Nanotube Growth Via Spray Pyrolysis, Robert Welch Call Oct 2011

Carbon Nanotube Growth Via Spray Pyrolysis, Robert Welch Call

Robert W Call

Spray pyrolysis is a promising method to create carbon nanotube forests (CNFs) on various surfaces. By injecting metallocene-hydrocarbon solutions into a heated quartz reactor, catalyst particles and carbon nanotubes can be formed simultaneously. Factors that affect CNF growth include the precursor concentration, injection rate and duration, carrier gas flow rate, substrate surface, growth temperature, and the composition of gases inside the reactor. The CNF morphologies affected by these factors will be presented and, hopefully, an optimum condition will be found.


Boundary Effects In Large-Aspect-Ratio Lasers, G.K. Harkness, W.J. Firth, John B. Geddes, J.V Moloney, E.M. Wright Oct 2011

Boundary Effects In Large-Aspect-Ratio Lasers, G.K. Harkness, W.J. Firth, John B. Geddes, J.V Moloney, E.M. Wright

John B. Geddes

We study theoretically the effect of transverse boundary conditions on the traveling waves foundin infinitely extended and positively detuned laser systems. We find that for large-aspect-ratiosystems, well above threshold and away from the boundaries, the traveling waves persist. Sourceand sink defects are observed on the boundaries, and in very-large-aspect-ratio systems these defectscan also exist away from the boundaries. The transverse size of the sink defect, relative to the sizeof the transverse domain, is important in determining the final pattern observed, and so, close tothreshold, standing waves are always observed.


Dynamic High Contrast Reflective Coloration From Responsive Polymer/Cholesteric Liquid Crystal Architectures, Michael E. Mcconney, Timothy J. White, Vincent P. Tondiglia, Lalgudi V. Natarajan, Deng-Ke Yang, Timothy J. Bunning Oct 2011

Dynamic High Contrast Reflective Coloration From Responsive Polymer/Cholesteric Liquid Crystal Architectures, Michael E. Mcconney, Timothy J. White, Vincent P. Tondiglia, Lalgudi V. Natarajan, Deng-Ke Yang, Timothy J. Bunning

Deng-Ke Yang

We report on high reflectivity CLC structures (R > 50%) whose wavelength can be thermally tuned reversibly by a de-swelling/re-swelling transition unique to ordered solvent-gel systems. The system contains no chiral dopant and the coloration is completely induced by a responsive chiral structured gel. The de-swelling transition, leading to blue tuning, occurs at the nematic-isotropic transition of the liquid crystal, which is a result of a mismatch in the orientational energy of the isotropic liquid crystal and the anisotropic gel. The re-swelling transition subsequently occurs at the nematic-isotropic transition of gel, due to the miscibility of the isotropic liquid crystal ...


Hubble Space Telescope Imaging Of Post-Starburst Quasars, S. L. Cales, M. S. Brotherton, Zhaohui Shang, Vardha Nicola Bennert, Gabriela Canalizo, R. Stoll, R. Ganguly, D. Vanden Berk, Cassandra Paul, A. Diamond-Stanic Oct 2011

Hubble Space Telescope Imaging Of Post-Starburst Quasars, S. L. Cales, M. S. Brotherton, Zhaohui Shang, Vardha Nicola Bennert, Gabriela Canalizo, R. Stoll, R. Ganguly, D. Vanden Berk, Cassandra Paul, A. Diamond-Stanic

Cassandra Paul

We present images of 29 post-starburst quasars (PSQs) from a Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Wide Field Channel Snapshot program. These broadlined active galactic nuclei (AGNs) possess the spectral signatures of massive (Mburst ∼ 1010 M#4;), moderate-aged stellar populations (hundreds of Myr). Thus, their composite nature provides insight into the AGN–starburst connection. We measure quasar-to-host galaxy light contributions via semi-automated two-dimensional light profile fits of point-spread-function-subtracted images. We examine the host morphologies and model the separate bulge and disk components. The HST/ACS-F606W images reveal an equal number of spiral (13/29) and early-type (13 ...


Extraction Of Signals From Chaotic Laser Data, John B. Geddes, Kevin Short, Kelly Black Oct 2011

Extraction Of Signals From Chaotic Laser Data, John B. Geddes, Kevin Short, Kelly Black

John B. Geddes

Several experimental groups have demonstrated communication with chaotic lasers. We analyzedata collected from a message-modulated erbium-doped fiber-ring laser (provided by VanWiggerenand Roy). We show that the transmitted signal is dominated by convolution of the message with theresponse function of the laser. A simple model based on the topology of the laser allows us to recovera hidden message. While prior estimates indicate that the laser dynamics are high dimensional, weshow that only four parameters are required, each of which can be recovered from the transmittedsignal alone.


Mass Flow Through Solid 4he Induced By The Fountain Effect, M. W. Ray, Robert B. Hallock Oct 2011

Mass Flow Through Solid 4he Induced By The Fountain Effect, M. W. Ray, Robert B. Hallock

Robert Hallock

Using an apparatus that allows superfluid liquid 4_He to be in contact with hcp solid 4_He at pressures greater than the bulk melting pressure of the solid, we have performed experiments that show evidence for 4_He mass flux through the solid and the likely presence of superfluid inside the solid. We present results that show that a thermomechanical equilibrium in quantitative agreement with the fountain effect exists between two liquid reservoirs connected to each other through two superfluid-filled Vycor rods in series with a chamber filled with solid〖 4〗_He. We use the thermomechanical effect to induce flow through the ...