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Full-Text Articles in Physics

A Perturbation Drbem Model For Weakly Nonlinear Wave Run-Ups Around Islands, Tim Marchant Dec 2008

A Perturbation Drbem Model For Weakly Nonlinear Wave Run-Ups Around Islands, Tim Marchant

Tim Marchant

In this paper, the dual reciprocity boundary element method (DRBEM) based on the perturbation method is presented for calculating run-ups of weakly nonlinear long waves scattered by islands. Under the assumption that the incident waves are harmonic, the time-dependent nonlinear Boussinesq equations are transformed into three time-independent linear equations by using the perturbation method, where, besides nonlinearity ε, the dispersion μ2 is also included in the perturbed expansion. The first-order solution η0 is found by using the linear long-wave equations. Then η0 is used in two second-order governing equations related to the dispersion and nonlinearity, respectively. Since no any omission ...


Performance Of A Single-Crystal Diamond-Pixel Telescope, R. Hall-Wilton, V. Ryjov, M. Pernicka, V. Halyo, B. Harrop, A. Hunt, D. Marlow, E. Bartz, J. Doroshenko, D. Hits, S. Schnetzer, R. Stone, W. Bugg, M. Hollingsworth, Stefan Spanier, W. Johns Dec 2008

Performance Of A Single-Crystal Diamond-Pixel Telescope, R. Hall-Wilton, V. Ryjov, M. Pernicka, V. Halyo, B. Harrop, A. Hunt, D. Marlow, E. Bartz, J. Doroshenko, D. Hits, S. Schnetzer, R. Stone, W. Bugg, M. Hollingsworth, Stefan Spanier, W. Johns

stefan spanier

We describe the results from a beam test of a telescope consisting of three planes of single-crystal, diamond pixel detectors. This telescope is a prototype for a proposed small-angle luminosity monitor, the Pixel Luminosity Telescope (PLT), for CMS. We recorded the pixel addresses and pulse heights of all pixels over threshold as well as the fast-or signals from all three telescope planes. We present results on the telescope performance including occupancies, pulse heights, fast-or efficiencies and particle tracking. These results show that the PLT design concept is sound and indicate that the project is ready to proceed with the next ...


Identifying Ranges Of Student Mental Health Using Latent Class Analysis, Katherine Dix Dec 2008

Identifying Ranges Of Student Mental Health Using Latent Class Analysis, Katherine Dix

Dr Katherine Dix

The author has investigated teacher and parent assessments of students' mental health based upon data from the evaluation of KidsMatter, the Australian mental health promotion, prevention and early intervention initiative. She notes that the prevalence of child and adolescent mental health disorders has increased over the last 50 years, according to investigators, to the extent that it is now of major concern in Australia. In order to counter this trend, national initiatives, such as KidsMatter, have been trialled with the intention of improving the mental health outcomes for Australian primary school children. The author discusses the use of multiple instruments ...


Comments On The Minimal Vectorial Standard Model, Mohamed M. Anber, Ufuk Aydemir, John Donoghue, Preema Pais Dec 2008

Comments On The Minimal Vectorial Standard Model, Mohamed M. Anber, Ufuk Aydemir, John Donoghue, Preema Pais

John Donoghue

We explore the available parameter space of the minimal vectorial Standard Model. In this theory, the gauge currents are initially vectorial but the Higgs sector produces chiral mass eigenstates, leading to a set of heavy right-handed mirror particles. We describe the phenomenology of the residual parameter space and suggest that the model will be readily tested at the LHC.


Living Anionic Polymerization Using A Microfluidic Reactor, Kazunori Iida, Thomas Q. Chastek, Kathryn L. Beers, Kevin Cavicchi, Jaehun Chun, Fasolka J. Michael Dec 2008

Living Anionic Polymerization Using A Microfluidic Reactor, Kazunori Iida, Thomas Q. Chastek, Kathryn L. Beers, Kevin Cavicchi, Jaehun Chun, Fasolka J. Michael

Kevin Cavicchi

Living anionic polymerizations were conducted within aluminum-polyimide microfluidic devices. Polymerizations of styrene in cyclohexane were carried out at various conditions, including elevated temperature (60 degrees C) and high monomer concentration (42%, by volume). The reactions were safely maintained at a controlled temperature at all points in the reactor. Conducting these reactions in a batch reactor results in uncontrolled heat generation with potentially dangerous rises in pressure. Moreover, the microfluidic nature of these devices allows for flexible 2D designing of the flow channel. Four flow designs were examined (straight, periodically pinched, obtuse zigzag, and acute zigzag channels). The ability to use ...


Alamethicin In Lipid Bilayers: Combined Use Of X-Ray Scattering And Md Simulations, Jianjun Pan, D. Peter Tieleman, John F. Nagle, Norbert Kučerka, Prof. Stephanie Tristram-Nagle Ph.D. Dec 2008

Alamethicin In Lipid Bilayers: Combined Use Of X-Ray Scattering And Md Simulations, Jianjun Pan, D. Peter Tieleman, John F. Nagle, Norbert Kučerka, Prof. Stephanie Tristram-Nagle Ph.D.

Prof. Stephanie Tristram-Nagle Ph.D.

We study fully hydrated bilayers of two di-monounsaturated phospholipids diC18:1PC (DOPC) and diC22:1PC with varying amounts of alamethicin (Alm). We combine the use of X-ray diffuse scattering and molecular dynamics simulations to determine the orientation of alamethicin in model lipids. Comparison of the experimental and simulated form factors shows that Alm helices are inserted transmembrane at high humidity and high concentrations, in agreement with earlier results. The X-ray scattering data and the MD simulations agree that membrane thickness changes very little up to 1/10 Alm/ DOPC. In contrast, the X-ray data indicate that the thicker diC22:1PC ...


Patent Citation Networks Revisited: Signs Of A Twenty-First Century Change, Katherine J. Strandburg, Gabor Csardi, Laszlo Zalanyi, Jan Tobochnik, Peter Erdi Dec 2008

Patent Citation Networks Revisited: Signs Of A Twenty-First Century Change, Katherine J. Strandburg, Gabor Csardi, Laszlo Zalanyi, Jan Tobochnik, Peter Erdi

Katherine J. Strandburg

This Article reports an empirical study of the network composed of patent “nodes” and citation “links” between them. It builds on an earlier study, in which we argued that trends in the growth of the patent citation network provide evidence that the explosive growth in patenting in the late twentieth century was due at least in part to the issuance of increasingly trivial patents. We defined a measure of patent stratification based on comparative probability of citation; an increase in this measure suggests that the USPTO is issuing patents of comparatively less technological significance. Provocatively, we found that stratification increased ...


Appearance Of A Fractional Stokes-Einstein Relation In Water And A Structural Interpretation Of Its Onset, L. Xu, F. Mallamace, Z. Yan, Francis W. Starr, S. V. Buldyrev, H. E. Stanley Dec 2008

Appearance Of A Fractional Stokes-Einstein Relation In Water And A Structural Interpretation Of Its Onset, L. Xu, F. Mallamace, Z. Yan, Francis W. Starr, S. V. Buldyrev, H. E. Stanley

Francis Starr

The Stokes–Einstein relation has long been regarded as one of the hallmarks of transport in liquids. It predicts that the self-diffusion constant D is proportional to (τ/T)−1, where τ is the structural relaxation time and T is the temperature. Here, we present experimental data on water confirming that, below a crossover temperature T× ≈ 290 K, the Stokes– Einstein relation is replaced by a ‘fractional’ Stokes–Einstein relation D ∼ (τ/T)−ζ with ζ ≈ 3/5 (refs 1–6). We interpret the microscopic origin of this crossover by analysing the OH- stretch region of the Fourier transform infrared ...


Review Of Biocd Physics And Technology, David D. Nolte Dec 2008

Review Of Biocd Physics And Technology, David D. Nolte

David D Nolte

Spinning biodisks have advantages that make them attractive for specialized biochip applications. The two main classes of spinning biodisks are microfluidic disks and bio-optical compact disks BioCD. Microfluidic biodisks take advantage of noninertial pumping for lab-on-a-chip devices using noninertial valves and switches under centrifugal and Coriolis forces to distribute fluids about the disks. BioCDs use spinning-disk interferometry, under the condition of common-path phase quadrature, to perform interferometric label-free detection of molecular recognition and binding. The optical detection of bound molecules on a disk is facilitated by rapid spinning that enables high-speed repetitive sampling to eliminate 1/ f noise through common-mode ...


Problems Of Local Fractional Definite Integral Of The One-Variable Non-Differentiable Function, Yang Xiao-Jun Dec 2008

Problems Of Local Fractional Definite Integral Of The One-Variable Non-Differentiable Function, Yang Xiao-Jun

Xiao-Jun Yang

It is proposed that local fractional calculas introduced by Kolwankar and Gangal is extended by the concept of Jumarie’s fractional calculus and local fractional definite integral is redefined. The properties and the theorems of local fractional calculus are discussed in this paper.


Frequency Domain Bayesian Inversion And Impedance Uncertainty Estimates, Michael Broadhead Dec 2008

Frequency Domain Bayesian Inversion And Impedance Uncertainty Estimates, Michael Broadhead

Michael Broadhead

No abstract provided.


Multilayered Structures In The Ionosphere F2 Region And Impulse-Like Increase Of The Nightglow Red 630 Nm Line Intensity As A Result Of Influence Of Shear Excited Atmospheric Vortical Perturbations, G. G. Didebulidze, Levan Lomidze, N. B. Gudadze, M. Todua Dec 2008

Multilayered Structures In The Ionosphere F2 Region And Impulse-Like Increase Of The Nightglow Red 630 Nm Line Intensity As A Result Of Influence Of Shear Excited Atmospheric Vortical Perturbations, G. G. Didebulidze, Levan Lomidze, N. B. Gudadze, M. Todua

Levan Lomidze

It is shown that the formation of multilayered structures in the midlatitude ionosphere F 2 layer can be caused by atmospheric vortical perturbation (shear wave) evolving in the meridional wind with linear zonal shear and can be accompanied by an impulse-like increase (with duration about 1–3 h) in the red 630 nm line total nightglow intensity. The shear wave can produce an enhancement of the northward wind (or decrease in the southward one), which can cause a downward motion of the F 2 layer peak height resulting in the impulse-like increase in the red line intensity. An important increase ...


A Percolation-Theoretic Approach To Spin Glass Phase Transitions, Jonathan Machta, C. M. Newman, D. L. Stein Dec 2008

A Percolation-Theoretic Approach To Spin Glass Phase Transitions, Jonathan Machta, C. M. Newman, D. L. Stein

Jonathan Machta

The magnetically ordered, low temperature phase of Ising ferromagnets is manifested within the associated Fortuin—Kasteleyn (FK) random cluster representation by the occurrence of a single positive density percolating cluster. In this paper, we review our recent work on the percolation signature for Ising spin glass ordering — both in the short-range Edwards—Anderson (EA) and infinite-range Sherrington—Kirkpatrick (SK) models — within a tworeplica FK representation and also in the different Chayes—Machta—Redner two-replica graphical representation. Numerical studies of the ±J EA model in dimension three and rigorous results for the SK model are consistent in supporting the conclusion that ...


Synchrotron Radiation-Based Characterization Of Gan- Based Mqw Structures And Strongly Correlated Materials, Sean M. O'Malley Dec 2008

Synchrotron Radiation-Based Characterization Of Gan- Based Mqw Structures And Strongly Correlated Materials, Sean M. O'Malley

Dissertations

The following dissertation applies synchrotron radiation-based characterization techniques to the fields of gallium nitrides, multiferroic manganites, and self-assembled nano-domain oxide films. These material systems were chosen due to their unusual properties and potential device applications, which have made them very attractive to the scientific community.

Synchrotron-based High Resolution X-ray Diffraction (HRXRD) was used to characterize the structural properties of GaN-based multiple quantum well (MQW) structures grown on trapezoidal shaped GaN ridges. Results where interpreted within the framework of vapor-phase diffusion and surface-migration effects during the metalorganic vapor phase epitaxial growth. The relatively short diffusion length of group- III precursors and ...


Detecting Topological Features Of Chaotic Fluid Flow, Nicholas T. Ouellette, Jerry P. Gollub Dec 2008

Detecting Topological Features Of Chaotic Fluid Flow, Nicholas T. Ouellette, Jerry P. Gollub

Department of Physics Papers

No abstract provided.


Terahertz Response Of Microfluidic-Jetted Fabricated 3d Flexible Metamaterials, Yew Li Hor Dec 2008

Terahertz Response Of Microfluidic-Jetted Fabricated 3d Flexible Metamaterials, Yew Li Hor

Dissertations

Conventional materials exhibit some restrictions on their electromagnetic properties. Especially in terahertz region, for example, materials that exhibit magnetic response are far less common in nature than materials that exhibit electric response. However, materials can be designed, namely artificial man-made metamaterials that exhibit electromagnetic properties that are not found in natural materials by adjusting, for example, the dielectric, magnetic or structural parameters of the constituent elements.

This dissertation demonstrates the use of new fabrication techniques to construct metamaterials in THz range via a material deposition system. The metamaterials are fabricated by stacking alternative layers with conventional designs such as single ...


Casimir Effect For Massless Fermions In One Dimension: A Force-Operator Approach, Dina Zhabinskaya, Jesse M. Kinder, Eugene J. Mele Dec 2008

Casimir Effect For Massless Fermions In One Dimension: A Force-Operator Approach, Dina Zhabinskaya, Jesse M. Kinder, Eugene J. Mele

Department of Physics Papers

We calculate the Casimir interaction between two short-range scatterers embedded in a background of one-dimensional massless Dirac fermions using a force-operator approach. We obtain the force between two finite-width square barriers and take the limit of zero width and infinite potential strength to study the Casimir force mediated by the fermions. For the case of identical scatterers, we recover the conventional attractive one-dimensional Casimir force. For the general problem with inequivalent scatterers, we find that the magnitude and sign of this force depend on the relative spinor polarizations of the two scattering potentials, which can be tuned to give an ...


Sub-Micron Parallel Laser Direct-Write, Christina Othon, Arnoldo Laracuente, H Ladoucuer, Bradley Ringeisen Dec 2008

Sub-Micron Parallel Laser Direct-Write, Christina Othon, Arnoldo Laracuente, H Ladoucuer, Bradley Ringeisen

Christina M Othon

We have developed a modified laser induced forward transfer (LIFT) technique which allows for the parallel deposition of hundreds of sub-micron features. The approach utilizes a self-assembled monolayer of monodisperse polystyrene microspheres as the focusing element. A monolayer of close-packed microspheres is formed on top of an ultra-thin quartz support (25 m thick), and a metallic thin film is then deposited on the underside of the quartz. This approach is different from previous parallel microsphere-assisted LIFT experiments that required the deposition of metal directly onto the surface of the periodic microsphere structure. For this study, an 800 nm, 130 fs ...


Is The Pamela Positron Excess Winos?, Scott Watson, Phill Grajek, Gordon L. Kane, Daniel J. Phalen, Aaron Pierce Dec 2008

Is The Pamela Positron Excess Winos?, Scott Watson, Phill Grajek, Gordon L. Kane, Daniel J. Phalen, Aaron Pierce

Physics

Recently the PAMELA satellite-based experiment reported an excess of galactic positrons that could be a signal of annihilating dark matter. The PAMELA data may admit an interpretation as a signal from a wino-like LSP of mass about 200 GeV, normalized to the local relic density, and annihilating mainly into W-bosons. This possibility requires the current conventional estimate for the energy loss rate of positrons be too large by roughly a factor of five. Data from anti-protons and gamma rays also provide tension with this interpretation, but there are significant astrophysical uncertainties associated with their propagation. It is not unreasonable to ...


Gravitational Wave Burst Source Direction Estimation Using Time And Amplitude Information, J. Markowitz, M. Zanolin, L. Cadonati, E. Katsavounidis Dec 2008

Gravitational Wave Burst Source Direction Estimation Using Time And Amplitude Information, J. Markowitz, M. Zanolin, L. Cadonati, E. Katsavounidis

Michele Zanolin

In this article we study two problems that arise when using timing and amplitude estimates from a network of interferometers (IFOs) to evaluate the direction of an incident gravitational wave burst (GWB). First, we discuss an angular bias in the least squares timing-based approach that becomes increasingly relevant for moderate to low signal-to-noise ratios. We show how estimates of the arrival time uncertainties in each detector can be used to correct this bias. We also introduce a stand alone parameter estimation algorithm that can improve the arrival time estimation and provide root-sum-squared strain amplitude (h(rss)) values for each site ...


Self-Consistent Calculations Of Strain-Induced Band Gap Changes In Semiconducting (N, 0) Carbon Nanotubes, Pavan Kumar Valavala, Douglas R. Banyai, Max Seel, Ranjit Pati Dec 2008

Self-Consistent Calculations Of Strain-Induced Band Gap Changes In Semiconducting (N, 0) Carbon Nanotubes, Pavan Kumar Valavala, Douglas R. Banyai, Max Seel, Ranjit Pati

Department of Physics Publications

First-principles density-functional calculations of the electronic structure, energy band gaps (Eg), and strain-induced band gap changes in moderate-gap single-walled (n,0) carbon nanotubes (SWNTs) are presented. It is confirmed that (n,0) SWNTs fall into two classes depending upon n mod 3=1 or 2. Eg is always lower for “mod 1” than for “mod 2” SWNTs of similar diameter. For n<10, strong curvature effects dominate Eg; from n=10 to 17, the Eg oscillations, amplified due to σ−π mixing, decrease and can be explained very well with a tight-binding model which includes trigonal warping. Under strain, the two families ...


Statistics Of Bubble Rearrangement Dynamics In A Coarsening Foam, Alex Gittings, Douglas J. Durian Dec 2008

Statistics Of Bubble Rearrangement Dynamics In A Coarsening Foam, Alex Gittings, Douglas J. Durian

Department of Physics Papers

We use speckle-visibility spectroscopy to measure the time dependence of bubble rearrangement events that are driven by coarsening in an aqueous foam. This technique gives the time trace for the average scattering site speed within a prescribed volume of the sample. Results are analyzed in terms of distributions of event times, event speeds, and event displacements. The distribution of rest times between successive events is also measured; comparison with diffusing-wave spectroscopy results shows that the spatial structure of a typical event consists of a core of only a few bubbles which undergo topology change plus a surrounding shell of bubbles ...


Constructing Diabatic States From Adiabatic States: Extending Generalized Mulliken–Hush To Multiple Charge Centers With Boys Localization, Joseph E. Subotnik, Robert J. Cave, Sina Yeganeh, Mark A. Ratner Dec 2008

Constructing Diabatic States From Adiabatic States: Extending Generalized Mulliken–Hush To Multiple Charge Centers With Boys Localization, Joseph E. Subotnik, Robert J. Cave, Sina Yeganeh, Mark A. Ratner

All HMC Faculty Publications and Research

This article shows that, although Boys localization is usually applied to single-electron orbitals, the Boys method itself can be applied to many electron molecular states. For the two-state charge-transfer problem, we show analytically that Boys localization yields the same charge-localized diabatic states as those found by generalized Mulliken–Hush theory. We suggest that for future work in electron transfer, where systems have more than two charge centers, one may benefit by using a variant of Boys localization to construct diabatic potential energy surfaces and extract electronic coupling matrix elements. We discuss two chemical examples of Boys localization and propose a ...


Drizzle Rates Versus Cloud Depths For Marine Stratocumuli, A. B. Kostinski Dec 2008

Drizzle Rates Versus Cloud Depths For Marine Stratocumuli, A. B. Kostinski

Department of Physics Publications

Marine stratocumuli make a major contribution to Earth’s radiation budget. Drizzle in such clouds can greatly affect their albedo, lifetime and fractional coverage, so drizzle rate prediction is important. Here we examine a question: does a drizzle rate (R) depend on cloud depth (H) and/or drop number concentration n in a simple way? This question was raised empirically in several recent publications and an approximate H3/n dependence was observed. Here we suggest a simple explanation for H3 scaling from viewing the drizzle rate as a sedimenting volume fraction ( f ) of water drops (radius r) in air, i ...


Search For The Standard Model Higgs Boson In The Missing Energy And Acoplanar B-Jet Topology At √S = 1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Dec 2008

Search For The Standard Model Higgs Boson In The Missing Energy And Acoplanar B-Jet Topology At √S = 1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We report a search for the standard model Higgs boson in the missing energy and acoplanar b-jet topology, using an integrated luminosity of 0.93 fb-1 recorded by the D0 detector at the Fermilab Tevatron pp Collider. The analysis includes signal contributions from ppZHννbb, as well as from WH production in which the charged lepton from the W boson decay is undetected. Neural networks are used to separate signal from background. In the absence of a signal, we set limits on σ (ppVH) x B(H → bb) at the 95% C.L. of 2.6 ...


Spiral Spin Structures And Origin Of The Magnetoelectric Coupling In Ymn2O5, Junghwa Kim, Seunghun Lee, Sungil Park, Michel Kenzelmann, A. Brooks Harris, Jürg Schefer, Jaeho Chung, Charles F. Majkrzak, Masayasu Takeda, Shuichi Wakimoto, Soonyong Park, Sangwook Cheong, Masaaki Matsuda, Hisamichi Kimura, Yukio Noda, Kazuhisa Kakurai Dec 2008

Spiral Spin Structures And Origin Of The Magnetoelectric Coupling In Ymn2O5, Junghwa Kim, Seunghun Lee, Sungil Park, Michel Kenzelmann, A. Brooks Harris, Jürg Schefer, Jaeho Chung, Charles F. Majkrzak, Masayasu Takeda, Shuichi Wakimoto, Soonyong Park, Sangwook Cheong, Masaaki Matsuda, Hisamichi Kimura, Yukio Noda, Kazuhisa Kakurai

Department of Physics Papers

By combining neutron four-circle diffraction and polarized neutron-diffraction techniques we have determined the complex spin structures of a multiferroic YMn2O5 that exhibits two ferroelectric phases at low temperatures. The obtained magnetic structure has spiral components in both the low-temperature ferroelectric phases that are magnetically commensurate and incommensurate, respectively. Among proposed microscopic theories for the magnetoelectric coupling, our results are consistent with both the spin-current mechanism and the magnetostriction mechanism. Our results also explain why the electric polarization changes at the low-temperature commensurate-to-incommensurate phase transition.


Matter-Wave Self-Imaging By Atomic Center-Of-Mass Motion Induced Interference, Ke Li, L. Deng, E. W. Hagley, Marvin G. Payne, M. S. Zhan Dec 2008

Matter-Wave Self-Imaging By Atomic Center-Of-Mass Motion Induced Interference, Ke Li, L. Deng, E. W. Hagley, Marvin G. Payne, M. S. Zhan

Marvin G. Payne

We demonstrate matter-wave self-imaging resulting from atomic center-of-mass motion-based interference. We show that non-negligible atomic center-of-mass motion and an instantaneous Doppler shift can drastically change the condensate momentum distribution, resulting in a periodic collapse and the recurrence of condensate diffraction probability as a function of the stationary light-field pulsing time. The observed matter-wave self-imaging is characterized by an atomic center-of-mass motion induced population amplitude interference in the presence of the light field that simultaneously minimizes all high (n≥1) diffraction orders and maximizes the zeroth diffraction component.


Switchable Polarization-Independent Liquid-Crystal Fabry-Perot Filter, Enkh-Amgalan Dorjgotov, Achintya K. Bhowmik, Philip J. Bos Dec 2008

Switchable Polarization-Independent Liquid-Crystal Fabry-Perot Filter, Enkh-Amgalan Dorjgotov, Achintya K. Bhowmik, Philip J. Bos

Philip J. Bos

A new approach to a polarization-independent twisted liquid-crystal (LC) structure, where phase difference between orthogonal eigenmodes is tuned to be an integer multiple of 2 pi, is demonstrated with a numerical model. For select wavelengths, polarization-independent operation can be achieved by tuning the twist rate and thickness of the LC cavity Applications can be found in polarization-independent switches and field sequential wavelength selection devices.


Field Theory Of Directed Percolation With Long-Range Spreading, Hans-Karl Janssen, Olaf Stenull Dec 2008

Field Theory Of Directed Percolation With Long-Range Spreading, Hans-Karl Janssen, Olaf Stenull

Department of Physics Papers

It is well established that the phase transition between survival and extinction in spreading models with short-range interactions is generically associated with the directed percolation (DP) universality class. In many realistic spreading processes, however, interactions are long ranged and well described by Lévy flights—i.e., by a probability distribution that decays in d dimensions with distance r as r−d−σ. We employ the powerful methods of renormalized field theory to study DP with such long-range Lévy-flight spreading in some depth. Our results unambiguously corroborate earlier findings that there are four renormalization group fixed points corresponding to, respectively, short-range ...


Magnetic-Field Induced Isotropic To Nematic Liquid Crystal Phase Transition, T. Ostapenko, D. B. Wiant, Samuel N. Sprunt, Antal Jákli, Jim T. Gleeson Dec 2008

Magnetic-Field Induced Isotropic To Nematic Liquid Crystal Phase Transition, T. Ostapenko, D. B. Wiant, Samuel N. Sprunt, Antal Jákli, Jim T. Gleeson

Chemical Physics Publications

We report on measurements of magnetic-field induced nematic order in the bent-core liquid crystal 4-chlororesorcinol bis[4-(4-n-dodecyloxybenzoyloxy) benzoate]. Using the 31 T solenoid at the National High Magnetic Field Laboratory, we have observed, at temperatures less than 1 degrees above the clearing point, a first-order transition to the nematic phase. The critical magnetic field at which this occurs increases with temperature. We discuss these results within the context of both Maier-Saupe and Landau-de Gennes mean-field models for the nematic-isotropic transition. The implications of possible tetrahedratic order are also discussed. To our knowledge, this is the first observation of such ...