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Articles 1 - 30 of 51
Full-Text Articles in Physics
Galfit-Ing Agn Host Galaxies In Cosmos: Hst Versus Subaru, Callum Dewsnap, Pauline Barmby, Sarah C. Gallagher, C. Megan Urry, Aritra Ghosh, Meredith C. Powell
Galfit-Ing Agn Host Galaxies In Cosmos: Hst Versus Subaru, Callum Dewsnap, Pauline Barmby, Sarah C. Gallagher, C. Megan Urry, Aritra Ghosh, Meredith C. Powell
Physics and Astronomy Publications
The COSMOS field has been extensively observed by most major telescopes, including Chandra, HST, and Subaru. HST imaging boasts very high spatial resolution and is used extensively in morphological studies of distant galaxies. Subaru provides lower spatial resolution imaging than HST but a substantially wider field of view with greater sensitivity. Both telescopes provide near-infrared imaging of COSMOS. Successful morphological fitting of Subaru data would allow us to measure morphologies of over 104 known active galactic nucleus (AGN) hosts, accessible through Subaru wide-field surveys, currently not covered by HST. The morphological parameters indicate the types of galaxies that host AGNs. …
Solar Cells, Lambert W And The Logwright Functions, Prabhat Lankireddy, Sibibalan Jeevanandam, Aditya Chaudhary, P. C. Deshmukh, Ken Roberts, S. R. Valluri
Solar Cells, Lambert W And The Logwright Functions, Prabhat Lankireddy, Sibibalan Jeevanandam, Aditya Chaudhary, P. C. Deshmukh, Ken Roberts, S. R. Valluri
Physics and Astronomy Publications
Algorithms that calculate the current-voltage (I-V) characteristics of a solar cell play an important role in processes that aim to improve the efficiency of a solar cell. I-V characteristics can be obtained from different models used to represent the solar cell, and the single diode model is a simple yet accurate model for common field implementations. However, the I-V characteristics are obtained by solving implicit equations, which involve repeated iterations and inherent errors associated with numerical methods used. Some methods use the Lambert W function to get an exact explicit formula, but often causes numerical overflow problems. The present work …
Modelling Of Covid-19 Using Fractional Differential Equations, Rishi Patel, P. Sainani, M. Brar, R. Patel, X. Li, J. Drozd, F. A. Chishtie, A. Benterki, T. C. Scott, S. R. Valluri
Modelling Of Covid-19 Using Fractional Differential Equations, Rishi Patel, P. Sainani, M. Brar, R. Patel, X. Li, J. Drozd, F. A. Chishtie, A. Benterki, T. C. Scott, S. R. Valluri
Physics and Astronomy Publications
In this work, we have described the mathematical modeling of COVID-19 transmission using fractional differential equations. The mathematical modeling of infectious disease goes back to the 1760s when the famous mathematician Daniel Bernoulli used an elementary version of compartmental modeling to find the effectiveness of deliberate smallpox inoculation on life expectancy. We have used the well-known SIR (Susceptible, Infected and Recovered) model of Kermack & McKendrick to extend the analysis further by including exposure, quarantining, insusceptibility and deaths in a SEIQRDP model. Further, we have generalized this model by using the solutions of Fractional Differential Equations to test the accuracy …
The Role Of R-Modes In Pulsar Spindown, Pulsar Timing And Gravitational Waves, Varenya Upadhyaya, Xiyuan Li, Xiyang Zhang, S. R. Valluri
The Role Of R-Modes In Pulsar Spindown, Pulsar Timing And Gravitational Waves, Varenya Upadhyaya, Xiyuan Li, Xiyang Zhang, S. R. Valluri
Physics and Astronomy Publications
Pulsars are fast spinning neutron stars that lose their rotational energy via various processes such as gravitational and magnetic radiation, particle acceleration and mass loss processes. This dissipation can be quantified by a spin-down equation that measures the rate of change of the frequency as a function of the rotational frequency itself. We explore the pulsar spin-down and consider the spin-down equation upto the seventh order in frequency. This seventh order term accounts for energy loss due to the gravitational radiation caused by a current type quadrupole in the pulsar due to r-modes. We derive the rotational frequency due to …
The Physical Properties Of Low-Redshift Felobal Quasars. I. Spectral-Synthesis Analysis Of The Broad Absorption-Line (Bal) Outflows Using Simbal, Hyunseop Choi, Karen M. Leighly, Donald M. Terndrup, Collin Dabbieri, Sarah C. Gallagher, Gordon T. Richards
The Physical Properties Of Low-Redshift Felobal Quasars. I. Spectral-Synthesis Analysis Of The Broad Absorption-Line (Bal) Outflows Using Simbal, Hyunseop Choi, Karen M. Leighly, Donald M. Terndrup, Collin Dabbieri, Sarah C. Gallagher, Gordon T. Richards
Physics and Astronomy Publications
We present the first systematic study of 50 low-redshift (0.66 < z < 1.63) iron low-ionization broad absorption-line quasars (FeLoBALQs) using SimBAL, which represents a more than five-fold increase in the number of FeLoBALQs with detailed absorption line spectral analyses. We found the outflows have a wide range of ionization parameters, − 4 ≲ log U ≲ 1.2 and densities, 2.8 ≲ log n ≲ 8 [ cm − 3 ] . The objects in our sample showed FeLoBAL gas located at a wide range of distances 0 ≲ log R ≲ 4.4 [pc], although we do not find any evidence for disk winds (with R ≪ 0.01 pc) in our sample. The outflow strength primarily depends on the outflow velocity with faster outflows found in quasars that are luminous or that have flat or redder spectral energy distributions. We found that ∼18% of the FeLoBALQs in the sample have the significantly powerful outflows needed for quasar feedback. Eight objects showed overlapping troughs in the spectra, and we identified eleven loitering outflow objects, a new class of FeLoBALQs that are characterized by low outflow velocities and high column density winds located log R ≲ 1 [pc] from the central engine. The FeLoBALs in loitering outflows objects do not show properties expected for radiatively driven winds, and these objects may represent a distinct population among FeLoBALQs. We discuss how the potential acceleration mechanisms and the origins of the FeLoBAL winds may differ for outflows at different locations in quasars.
Nustar Observations Of Intrinsically X-Ray Weak Quasar Candidates: An Obscuration-Only Scenario, Chaojun Wang, B. Luo, W. N. Brandt, D. M. Alexander, F. E. Bauer, Sarah C. Gallagher, Jian Huang, Hezhen Liu, D. Stern
Nustar Observations Of Intrinsically X-Ray Weak Quasar Candidates: An Obscuration-Only Scenario, Chaojun Wang, B. Luo, W. N. Brandt, D. M. Alexander, F. E. Bauer, Sarah C. Gallagher, Jian Huang, Hezhen Liu, D. Stern
Physics and Astronomy Publications
We utilize recent NuSTAR observations (co-added depth ≈55-120 ks) of PG 1001+054, PG 1254+047, and PHL 1811 to constrain their hard X-ray (≳5 keV) weakness and spectral shapes and thus to investigate the nature of their extreme X-ray weakness. These quasars showed very weak soft X-ray emission, and they were proposed to be intrinsically X-ray weak, with the X-ray coronae producing weak continuum emission relative to their optical/UV emission. However, the new observations suggest an alternative explanation. The NuSTAR 3-24 keV spectral shapes for PG 1001+054 and PHL 1811 are likely flat (effective power-law photon indices Γeff=1.0-0.6+0.5 and Γeff=1.4-0.7+0.8, respectively), …
The Physical Properties Of Low-Redshift Felobal Quasars. Iii. The Location And Geometry Of The Outflows, Hyunseop Choi, Karen M. Leighly, Collin Dabbieri, Donald M. Terndrup, Sarah C. Gallagher, Gordon T. Richards
The Physical Properties Of Low-Redshift Felobal Quasars. Iii. The Location And Geometry Of The Outflows, Hyunseop Choi, Karen M. Leighly, Collin Dabbieri, Donald M. Terndrup, Sarah C. Gallagher, Gordon T. Richards
Physics and Astronomy Publications
We present continued analysis of a sample of low-redshift iron low-ionization broad-absorption-line quasars (FeLoBALQs). Choi et al. presented SimBAL spectral analysis of broad-absorption-line (BAL) outflows in 50 objects. Leighly et al. analyzed the optical emission lines of 30 of those 50 objects and found that they are characterized by either a high accretion rate (L Bol/L Edd > 0.3) or low accretion rate (0.03 < L Bol/L Edd < 0.3). We report that the outflow velocity is inversely correlated with the BAL location among the high-accretion-rate objects, with the highest velocities observed in parsec-scale outflows. In contrast, the low-Eddington-ratio objects showed the opposite trend. We confirmed the known relationship between the outflow velocity and L Bol/L Edd and found that the scatter plausibly originates in the force multiplier (launch radius) in the low(high)-accretion-rate objects. A log volume filling factor between −6 and −4 was found in most outflows but was as high as −1 for low-velocity compact outflows. We investigated the relationship between the observed [O iii] emission and that predicted from the BAL gas. We found that these could be reconciled if the emission-line covering fraction depends on the Seyfert type and BAL location. The difference between the predicted and observed [O iii] luminosity is correlated with the outflow velocity, suggesting that [O iii] emission in high-Eddington-ratio objects may be broad and hidden under Fe ii emission. We suggest that the physical differences in the outflow properties as a function of location in the quasar and accretion rate point to different formation, acceleration, and confinement mechanisms for the two FeLoBALQ types.
Complex Energies And The Lambert W Function, A Das, B.G. Sidharth, K. Roberts, Sree Ram Valluri
Complex Energies And The Lambert W Function, A Das, B.G. Sidharth, K. Roberts, Sree Ram Valluri
Physics and Astronomy Publications
We apply the Lambert W function in the context of complex energy values in statistical systems of fermions and bosons. We derive the condition for the transformation connecting fermions and bosons. We discuss the physical significance of these results and investigate the conditions under which bosonization effects take place. The fermion and boson statistical and structural distributions discussed in this work suggest the possibility of their extensions to generalized Planck distributions.
Exploring Changes In Quasar Spectral Energy Distributions Across C Iv Parameter Space, Angelica B. Rivera, Gordon T. Richards, Sarah C. Gallagher, Trevor V. Mccaffrey, Amy L. Rankine, Paul C. Hewett, Ohad Shemmer
Exploring Changes In Quasar Spectral Energy Distributions Across C Iv Parameter Space, Angelica B. Rivera, Gordon T. Richards, Sarah C. Gallagher, Trevor V. Mccaffrey, Amy L. Rankine, Paul C. Hewett, Ohad Shemmer
Physics and Astronomy Publications
We examine the UV/X-ray properties of 1378 quasars in order to link empirical correlations to theoretical models of the physical mechanisms dominating quasars as a function of mass and accretion rate. The clarity of these correlations is improved when (1) using C iv broad emission line equivalent width (EQW) and blueshift (relative to systemic) values calculated from high signal-to-noise ratio reconstructions of optical/UV spectra and (2) removing quasars expected to be absorbed based on their UV/X-ray spectral slopes. In addition to using the traditional C iv parameter space measures of C iv EQW and blueshift, we define a “C iv …
Extremely Broad Ly Α Line Emission From The Molecular Intragroup Medium In Stephan's Quintet: Evidence For A Turbulent Cascade In A Highly Clumpy Multiphase Medium?, P. Guillard, P. N. Appleton, F. Boulanger, J. M. Shull, M. D. Lehnert, G. Pineau Des Forets, E. Falgarone, M. E. Cluver, C. K. Xu, Sarah C. Gallagher, P. A. Duc
Extremely Broad Ly Α Line Emission From The Molecular Intragroup Medium In Stephan's Quintet: Evidence For A Turbulent Cascade In A Highly Clumpy Multiphase Medium?, P. Guillard, P. N. Appleton, F. Boulanger, J. M. Shull, M. D. Lehnert, G. Pineau Des Forets, E. Falgarone, M. E. Cluver, C. K. Xu, Sarah C. Gallagher, P. A. Duc
Physics and Astronomy Publications
We present Hubble Space Telescope Cosmic Origin Spectrograph (COS) UV line spectroscopy and integral-field unit (IFU) observations of the intragroup medium in Stephan's Quintet (SQ). SQ hosts a 30 kpc long shocked ridge triggered by a galaxy collision at a relative velocity of 1000 km s-1, where large amounts of molecular gas coexist with a hot, X-ray-emitting, plasma. COS spectroscopy at five positions sampling the diverse environments of the SQ intragroup medium reveals very broad (≈2000 km s-1) Lyα line emission with complex line shapes. The Lyα line profiles are similar to or much broader than those of Hβ, [C …
The Hashtag Project: The First Submillimeter Images Of The Andromeda Galaxy From The Ground, Matthew W.L. Smith, Stephen A. Eales, Thomas G. Williams, Bumhyun Lee, Zongnan Li, Pauline Barmby, Martin Bureau, Scott Chapman, Brian S. Cho, Aeree Chung, Eun Jung Chung, Hui Hsuan Chung, Christopher J.R. Clark, David L. Clements, Timothy A. Davis, Ilse De Looze, David J. Eden, Gayathri Athikkat-Eknath, George P. Ford, Yu Gao, Walter Gear, Haley L. Gomez, Richard De Grijs, Jinhua He, Luis C. Ho, Thomas M. Hughes, Sihan Jiao, Zhiyuan Li, Francisca Kemper
The Hashtag Project: The First Submillimeter Images Of The Andromeda Galaxy From The Ground, Matthew W.L. Smith, Stephen A. Eales, Thomas G. Williams, Bumhyun Lee, Zongnan Li, Pauline Barmby, Martin Bureau, Scott Chapman, Brian S. Cho, Aeree Chung, Eun Jung Chung, Hui Hsuan Chung, Christopher J.R. Clark, David L. Clements, Timothy A. Davis, Ilse De Looze, David J. Eden, Gayathri Athikkat-Eknath, George P. Ford, Yu Gao, Walter Gear, Haley L. Gomez, Richard De Grijs, Jinhua He, Luis C. Ho, Thomas M. Hughes, Sihan Jiao, Zhiyuan Li, Francisca Kemper
Physics and Astronomy Publications
Observing nearby galaxies with submillimeter telescopes on the ground has two major challenges. First, the brightness is significantly reduced at long submillimeter wavelengths compared to the brightness at the peak of the dust emission. Second, it is necessary to use a high-pass spatial filter to remove atmospheric noise on large angular scales, which has the unwelcome side effect of also removing the galaxy's large-scale structure. We have developed a technique for producing high-resolution submillimeter images of galaxies of large angular size by using the telescope on the ground to determine the small-scale structure (the large Fourier components) and a space …
The X-Rays Wind Connection In Pg 2112+059, C. Saez, W. N. Brandt, F. E. Bauer, G. Chartas, T. Misawa, F. Hamann, Sarah C. Gallagher
The X-Rays Wind Connection In Pg 2112+059, C. Saez, W. N. Brandt, F. E. Bauer, G. Chartas, T. Misawa, F. Hamann, Sarah C. Gallagher
Physics and Astronomy Publications
We study the connection between the X-ray and ultraviolet (UV) properties of the broad absorption line (BAL) wind in the highly X-ray variable quasar PG 2112+059 by comparing Chandra-ACIS data with contemporaneous UV HST/STIS spectra in three different epochs. We observe a correlation whereby an increase in the equivalent widths (EWs) of the BALs is accompanied by a redder UV spectrum. The growth in the BAL EWs is also accompanied by a significant dimming in soft X-ray emission (≳2, keV), consistent with increased absorption. Variations in the hard X-ray emission (≳2, keV) are only accompanied by minor spectral variations of …
Fitting An Analytic Magnetic Field To A Prestellar Core, Gianfranco Bino, Shantanu Basu
Fitting An Analytic Magnetic Field To A Prestellar Core, Gianfranco Bino, Shantanu Basu
Physics and Astronomy Publications
We deploy and demonstrate the capabilities of the magnetic field model developed by Ewertowski & Basu by fitting observed polarimetry data of the prestellar core FeSt 1-457. The analytic hourglass magnetic field function derived directly from Maxwell's equations yields a central-to-surface magnetic field strength ratio in the equatorial plane, as well as magnetic field directions with relative magnitudes throughout the core. This fit emerges from a comparison of a single plane of the model with the polarization map that results from the integrated properties of the magnetic field and dust throughout the core. Importantly, our fit is independent of any …
Distances To Galactic X-Ray Binaries With Gaia Dr2, R. M. Arnason, H. Papei, P. Barmby, A. Bahramian, M. D. Gorski
Distances To Galactic X-Ray Binaries With Gaia Dr2, R. M. Arnason, H. Papei, P. Barmby, A. Bahramian, M. D. Gorski
Physics and Astronomy Publications
Precise and accurate measurements of distances to Galactic X-ray binaries (XRBs) reduce uncertainties in the determination of XRB physical parameters. We have cross-matched the XRB catalogues of Liu, van Paradijs & van den Heuvel to the results of Gaia Data Release 2. We identify 86 XRBs with a Gaia candidate counterpart, of which 32 are low-mass X-ray binaries (LMXBs) and 54 are high-mass X-ray binaries (HMXBs). Distances to Gaia candidate counterparts are, on average, consistent with those measured by Hipparcos and radio parallaxes. When compared to distances measured by Gaia candidate counterparts, distances measured using Type I X-ray bursts are …
On The Observational Difference Between The Accretion Disk-Corona Connections Among Super- And Sub-Eddington Accreting Active Galactic Nuclei, Hezhen Liu, B. Luo, W. N. Brandt, Michael S. Brotherton, Sarah C. Gallagher, Q. Ni, Ohad Shemmer, J. D. Timlin
On The Observational Difference Between The Accretion Disk-Corona Connections Among Super- And Sub-Eddington Accreting Active Galactic Nuclei, Hezhen Liu, B. Luo, W. N. Brandt, Michael S. Brotherton, Sarah C. Gallagher, Q. Ni, Ohad Shemmer, J. D. Timlin
Physics and Astronomy Publications
We present a systematic X-ray and multiwavelength study of a sample of 47 active galactic nuclei (AGNs) with reverberation mapping measurements. This sample includes 21 super-Eddington accreting AGNs and 26 sub-Eddington accreting AGNs. Using high-state observations with simultaneous X-ray and UV/optical measurements, we investigate whether super-Eddington accreting AGNs exhibit different accretion disk-corona connections compared to sub-Eddington accreting AGNs. We find tight correlations between the X-ray-to-UV/optical spectral slope parameter (α OX) and the monochromatic luminosity at 2500 Å (L 2500Å) for both the super- and sub-Eddington subsamples. The best-fit α OX-L 2500Å relations are consistent overall, indicating that super-Eddington accreting AGNs …
Gibbs Point Process Model For Young Star Clusters In M33, Dayi Li, Pauline Barmby
Gibbs Point Process Model For Young Star Clusters In M33, Dayi Li, Pauline Barmby
Physics and Astronomy Publications
We demonstrate the power of Gibbs point process models from the spatial statistics literature when applied to studies of resolved galaxies. We conduct a rigorous analysis of the spatial distributions of objects in the star formation complexes of M33, including giant molecular clouds (GMCs) and young stellar cluster candidates (YSCCs). We choose a hierarchical model structure from GMCs to YSCCs based on the natural formation hierarchy between them. This approach circumvents the limitations of the empirical two-point correlation function analysis by naturally accounting for the inhomogeneity present in the distribution of YSCCs. We also investigate the effects of GMCs' properties …
Fourier Transform Of The Continuous Gravitational Wave Signal, Sree Ram Valluri, V. Dergachev, X. Zhang, Farrukh Chishtie
Fourier Transform Of The Continuous Gravitational Wave Signal, Sree Ram Valluri, V. Dergachev, X. Zhang, Farrukh Chishtie
Physics and Astronomy Publications
The direct detection of continuous gravitational waves from pulsars is a much anticipated discovery in the emerging field of multimessenger gravitational wave (GW) astronomy. Because putative pulsar signals are exceedingly weak large amounts of data need to be integrated to achieve desired sensitivity. Contemporary searches use ingenious ad hoc methods to reduce computational complexity. In this paper we provide analytical expressions for the Fourier transform of realistic pulsar signals. This provides description of the manifold of pulsar signals in the Fourier domain, used by many search methods. We analyze the shape of the Fourier transform and provide explicit formulas for …
Discovery Of A Remarkably Powerful Broad Absorption-Line Quasar Outflow In Sdss J135246.37+423923.5, Hyunseop Choi, Karen M. Leighly, Donald M. Terndrup, Sarah C. Gallagher, Gordon T. Richards
Discovery Of A Remarkably Powerful Broad Absorption-Line Quasar Outflow In Sdss J135246.37+423923.5, Hyunseop Choi, Karen M. Leighly, Donald M. Terndrup, Sarah C. Gallagher, Gordon T. Richards
Physics and Astronomy Publications
Broad absorption-line (BAL) features in quasar spectra reveal an unambiguous signature of energetic outflows from central supermassive black holes, and thus, BAL quasars are prime targets for investigating the potential process of luminous quasar feedback on galaxies. We analyzed the rest-UV spectrum of an "overlapping trough" iron low-ionization broad absorption-line quasar (FeLoBAL) SDSS J135246.37+423923.5 using the novel spectral synthesis code SimBAL and discovered an extraordinarily fast and energetic BAL outflow. Our analysis revealed outflow velocities reaching ∼ -38,000 km s-1 with a velocity width of ∼ 10,000 km s-1, which is the largest FeLoBAL outflow velocity measured to date. The …
Lambert W Function Methods In Double Square Well And Waveguide Problems, Narola Harsh Bharatbhai, P C Deshmukh, Robert B. Scott, Ken Roberts, Sree Ram Valluri
Lambert W Function Methods In Double Square Well And Waveguide Problems, Narola Harsh Bharatbhai, P C Deshmukh, Robert B. Scott, Ken Roberts, Sree Ram Valluri
Physics and Astronomy Publications
Using methods related to the Lambert W function, we present solutions of two apparently different problems: (1) The one-dimensional double square well potential in quantum mechanics and (2) The transverse electric and magnetic modes for a step-index electromagnetic waveguide. The solution techniques provide insight into the bound energy states for the single and double square well problems and the allowed modes of propagation in a waveguide with varying refractive indices. The solutions can be viewed in either of two related complex plane representations. Comparison of the solution geometries suggests that interesting applications may be possible in nanostructures and devices which …
Stability Of Binary Colloidal Crystals Immersed In A Cholesteric Liquid Crystal, Setarehalsadat Changizrezaei, Colin Denniston
Stability Of Binary Colloidal Crystals Immersed In A Cholesteric Liquid Crystal, Setarehalsadat Changizrezaei, Colin Denniston
Physics and Astronomy Publications
In this paper, we model a number of both closed-packed and non-closed-packed crystals inside a cholesteric liquid crystal (LC) with different pitch values and nematic LC through the Landau–de Gennes free-energy method. We used binary boundary conditions (normal and planar anchoring) applied on the surface of colloids as we are interested in investigating the stability of binary crystals. The results indicate that body-centered-cubic (BCC) crystals have a lower-energy lattice defect structure than the diamond crystal, and the most energetically favorable BCC lattice can be formed in a cholesteric liquid crystal with a pitch value commensurate with the lattice spacing. Furthermore, …
An Analytic Study Of The Wiedemann-Franz Law And The Thermoelectric Figure Of Merit, Aakash Yadav, Pc Deshmukh, Ken Roberts, Nm Jisrawi, Sree Ram Valluri
An Analytic Study Of The Wiedemann-Franz Law And The Thermoelectric Figure Of Merit, Aakash Yadav, Pc Deshmukh, Ken Roberts, Nm Jisrawi, Sree Ram Valluri
Physics and Astronomy Publications
Advances in optimizing thermoelectric material efficiency have seen a parallel activity in theoretical and computational advances. In the current work, it is shown that the calculation of exact Fermi-Dirac integrals enables the generalization of the Wiedemann-Franz law (WF) to optimize the dimensionless thermoelectric figure of merit ZT. This is done by optimizing the Seebeck coefficient, the electrical conductivity and the thermal conductivity. In the calculation of the thermal conductivity, both electronic and phononic contributions are included. The solutions provide insight into the relevant parameter space including the physical significance of complex solutions and their dependence on the scattering parameter r …
Simulations Of Microscopic Propulsion Of Soft Elastic Bodies, David Urbanik, Shikhar Man Dwivedi, Colin Denniston
Simulations Of Microscopic Propulsion Of Soft Elastic Bodies, David Urbanik, Shikhar Man Dwivedi, Colin Denniston
Physics and Astronomy Publications
Using simulations that realistically model both hydrodynamic and elastic behavior, we study the motion of a microscopic, driven elastic sphere immersed in water. We first confirm the “jittery” relaxation recently predicted theoretically for an externally driven elastic sphere. The sphere is then divided in two and each section is driven internally with the two sections 180° out of phase. With periodic and perfectly symmetric driving, the elastic sphere spontaneously breaks symmetry and can attain macroscopic average swimming velocities to the right or left, the direction depending only on the initial state. With asymmetric driving the elastic sphere swims in one …
Controlling The Hydrophilicity And Cohesion During Deposition Of Highly Oriented Type I Collagen Films: An Approach For Biomedical Applications, Karina Ambrock, Bernd Grohe, Silvia Mittler
Controlling The Hydrophilicity And Cohesion During Deposition Of Highly Oriented Type I Collagen Films: An Approach For Biomedical Applications, Karina Ambrock, Bernd Grohe, Silvia Mittler
Physics and Astronomy Publications
Using the Langmuir-Blodgett (LB) technology we have pioneered a straightforward and low-cost approach to fabricate highly oriented collagen in thin film format (thickness: ~20 nm, surface areas: 2.5 x ~6.0 cm). An important factor for the use of these films is their cohesion under various conditions. Film formation was studied by coating hydrophilic or hydrophobic glass substrates. The fresh or aged (2 ½ years, -18°C.) collagen solutions used for this purpose either contained collagen network-stabilizing agents (n-propanol or phosphate ions) or were prepared without these stabilizers. Film formation on the air/water interface was analyzed by pressure-area isotherms. Maximum surface pressures …
A Mass-Producible And Versatile Sensing System: Localized Surface Plasmon Resonance Excited By Individual Waveguide Modes, Zhutian Ding, James M. Stubbs, Danielle Mcrae, Johanna M. Blacquiere, François Lagugné-Labarthet, Silvia Mittler
A Mass-Producible And Versatile Sensing System: Localized Surface Plasmon Resonance Excited By Individual Waveguide Modes, Zhutian Ding, James M. Stubbs, Danielle Mcrae, Johanna M. Blacquiere, François Lagugné-Labarthet, Silvia Mittler
Physics and Astronomy Publications
A plasmonic sensing system that allows the excitation of localized surface plasmon resonance (LSPR) by individual waveguide modes is presented conceptually and experimentally. Any change in the local environment of the gold nanoparticles (AuNPs) alters the degree of coupling between LSPR and a polymer slab waveguide, which then modulates the transmission-output signal. In comparison to conventional LSPR sensors, this system is less susceptible to optical noise and positional variation of signals. Moreover, it enables more freedom in the exploitation of plasmonic hot spots with both transverse electric (TE) and transverse magnetic (TM) modes. Through real-time measurement, it is demonstrated that …
Narrowing Of Plasmon Resonance Peaks As An Ensemble Effect, Zhutian Ding, James M. Stubbs, Silvia Mittler
Narrowing Of Plasmon Resonance Peaks As An Ensemble Effect, Zhutian Ding, James M. Stubbs, Silvia Mittler
Physics and Astronomy Publications
The frequency of localized surface plasmon resonance (LSPR) displayed by gold nanoparticles (AuNPs) redshifts as a function of their local refractive index, which renders them valuable transducers for sensing applications. An ensemble hypothesis is presented herein, along with spectroscopic evidence, using the biotin-streptavidin system on immobilized AuNPs to interpret the decrease in ensemble linewidth (ELW) consistently observed upon functionalization of plasmonic nanoparticles and the subsequent analyte binding. These results demonstrate that ELW can be used to monitor recognition reactions, providing spectral details and a possible sensitivity enhancement to the conventional wavelength sensing. A novel sensing platform allowing the simultaneous measurement …
Photonic Band Structure Of Diamond Colloidal Crystals In A Cholesteric Liquid Crystal, Setarehalsadat Changizrezaei, Colin Denniston
Photonic Band Structure Of Diamond Colloidal Crystals In A Cholesteric Liquid Crystal, Setarehalsadat Changizrezaei, Colin Denniston
Physics and Astronomy Publications
In this paper, we demonstrate the presence of a photonic band gap for a diamond lattice structure made of particles with normal anchoring inside a cholesteric liquid crystal. As is typical for liquid crystals (LCs), there is considerable contrast between the dielectric constant parallel ε∥ and perpendicular ε⊥ to the director, with ε∥/ε⊥∼4 here. It is shown that the size of the photonic band gap is directly related to the size of colloidal particles and the contrast between the dielectric constant in the particles and the extreme values of ε in the LC medium (one needs either ε in the …
Zr-Doped Tio2 As A Thermostabilizer In Plasmon-Enhanced Dye-Sensitized Solar Cells, Anastasia Pasche, Bernd Grohe, Silvia Mittler, Paul A. Charpentier
Zr-Doped Tio2 As A Thermostabilizer In Plasmon-Enhanced Dye-Sensitized Solar Cells, Anastasia Pasche, Bernd Grohe, Silvia Mittler, Paul A. Charpentier
Physics and Astronomy Publications
Harvesting solar energy is a promising solution toward meeting the world’s evergrowing energy demand. Dye-sensitized solar cells (DSSCs) are hybrid organic–inorganic solar cells with tremendous potential for commercial application, but they are plagued by in efficiency due to their poor sunlight absorption. Plasmonic silver nanoparticles (AgNPs) have been shown to enhance the absorptive properties of DSSCs, but their plasmonic resonance can cause thermal damage resulting in cell deterioration. Hence, the influence of Zr-doped TiO2 on the efficiency of plasmon-enhanced DSSCs was studied, showing that 5 mol.% Zr-doping of the photoactive TiO2 material can improve the photovoltaic performance of DSSCs by …
Vacuum Birefringence, The Photon Anomalous Magnetic Moment And The Neutron Star Rx J1856.5−3754, Sree Ram Valluri, J.W. Mielniczuk, Farrukh Chishtie, D. Lamm, S. Auddy
Vacuum Birefringence, The Photon Anomalous Magnetic Moment And The Neutron Star Rx J1856.5−3754, Sree Ram Valluri, J.W. Mielniczuk, Farrukh Chishtie, D. Lamm, S. Auddy
Physics and Astronomy Publications
We analyse the spectrum of the Hamiltonian of a photon propagating in a strong magnetic field B ∼ Bcr, where Bcr=m2e≃4.4×1013" role="presentation">Bcr=m2e≃4.4×1013 G is the Schwinger critical field. We show that the anomalous magnetic moment of a photon in the one-loop approximation is a non-decreasing function of the magnetic field B in the range 0 ≤ B ≤ 30 Bcr. We provide a numerical representation of the expression for the anomalous magnetic moment in terms of special functions. We find that the anomalous magnetic moment μγ of a photon for B = 30 B …
A Vision For Canadian Space Exploration, Ilaria Caiazzo, Sarah C. Gallagher, Jeremy Heyl
A Vision For Canadian Space Exploration, Ilaria Caiazzo, Sarah C. Gallagher, Jeremy Heyl
Physics and Astronomy Publications
We propose a sustained and balanced program in space exploration to fuel innovation in the space sector, support Canada's world-leading space researchers, inspire the next generation of scientists and innovators, and create thousands of highly skilled, well-paying jobs for Canadians. During the next decade we recommend a total investment of approximately $1B, increasing to $1.3B in each decade that follows, including a regular flagship mission that Canada would lead and a constellation of smaller missions, either led by Canada or in collaboration with international partners.
Heterogeneous Colloidal Particles Immersed In A Liquid Crystal, Setarehalsadat Changizrezaei, Colin Denniston
Heterogeneous Colloidal Particles Immersed In A Liquid Crystal, Setarehalsadat Changizrezaei, Colin Denniston
Physics and Astronomy Publications
In this paper, we explore anisotropic interactions between particles with heterogeneous boundary conditions inside both nematic and cholesteric liquid crystals. The results show that when particles are put at different distances and angles with respect to each other, new types of defect structures are produced, depending on the relative distances and directions. In a cholesteric liquid crystal, the value of the pitch affects the defect structures and induced forces. Moreover, it was observed that it is energetically favorable for the particles to remain in a plane parallel to the far-field director in a nematic liquid crystal, while for particles immersed …