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Physics

New submissions

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New submissions for Thu, 23 Nov 17

[1]  arXiv:1711.07991 [pdf, ps, other]
Title: Viscoelastic pipe flow is linearly unstable
Subjects: Fluid Dynamics (physics.flu-dyn); Applied Physics (physics.app-ph)

Newtonian pipe flow is known to be linearly stable at all Reynolds numbers. We report, for the first time, a linear instability of pressure driven pipe flow of a viscoelastic fluid, obeying the Oldroyd-B constitutive equation commonly used to model dilute polymer solutions. The instability is shown to exist at Reynolds numbers significantly lower than those at which transition to turbulence is typically observed for Newtonian pipe flow. Our results qualitatively explain experimental observations of transition to turbulence in pipe flow of dilute polymer solutions at flow rates where Newtonian turbulence is absent. The instability discussed here should form the first stage in a hitherto unexplored dynamical pathway to turbulence in polymer solutions. An analogous instability exists for plane Poiseuille flow.

[2]  arXiv:1711.07993 [pdf, other]
Title: Generalized Gilat-Raubenheimer method for density-of-states calculation in photonic crystals
Comments: 7 pages, 2 figures
Subjects: Applied Physics (physics.app-ph); Optics (physics.optics)

Efficient numeric algorithm is the key for accurate evaluation of density of states (DOS) in band theory. Gilat-Raubenheimer (GR) method proposed in 1966 is an efficient linear extrapolation method which was limited in specific lattices. Here, using an affine transformation, we provide a new generalization of the original GR method to any Bravais lattices and show that it is superior than the tetrahedron method and the adaptive Gaussian broadening method. Finally, we apply our generalized GR (GGR) method to compute DOS of various gyroid photonic crystals of topological degeneracies.

[3]  arXiv:1711.08003 [pdf]
Title: Electromechanically Tunable Metasurface Transmission Waveplate at Terahertz Frequencies
Subjects: Applied Physics (physics.app-ph)

Dynamic polarization control of light is essential for numerous applications ranging from enhanced imaging to materials characterization and identification. We present a reconfigurable terahertz metasurface quarter-waveplate consisting of electromechanically actuated micro-cantilever arrays. Our anisotropic metasurface enables tunable polarization conversion cantilever actuation. Specifically, voltage-based actuation provides mode selective control of the resonance frequency, enabling real-time tuning of the polarization state of the transmitted light. The polarization tunable metasurface has been fabricated using surface micromachining and characterized using terahertz time domain spectroscopy. We observe a ~230 GHz cantilever actuated frequency shift of the resonance mode, sufficient to modulate the transmitted wave from pure circular polarization to linear polarization. Our CMOS-compatible tunable quarter-waveplate enriches the library of terahertz optical components, thereby facilitating practical applications of terahertz technologies.

[4]  arXiv:1711.08015 [pdf]
Title: The Cosmic Ray Boron/Carbon Ratio Measured at Voyager and at AMS-2 from 10 MeV/nuc up to ~1 TeV/nuc and a Comparison With Propagation Calculations
Comments: 15 pages, 2 tables, 3 figures
Subjects: Space Physics (physics.space-ph); High Energy Astrophysical Phenomena (astro-ph.HE)

We have used new measurements of the B/C ratio in galactic cosmic rays at both low and high energies by the Voyager and AMS-2 spacecraft, respectively, along with propagation calculations using a truncated LBM to examine the implications of these new measurements over an extended energy range from a few MeV/nuc to 1 TeV/nuc. We find that the predictions from both the truncated LBM and the Diffusive Reacceleration model for GALPROP both agree with the Voyager and AMS-2 measurements of the B/C ratio to within +/- 10 percent throughout the entire energy range from 50 MeV/nuc to 1 TeV/nuc. The two propagation approaches also agree with each other to within +/-10 percent or less throughout this energy range. In effect a diffusion model, without significant additional acceleration, provides a match within +/-10 percent to the combined data from Voyager 1 and AMS-2 on the B/C ratio from 50 MeV/nuc to 1 TeV/nuc. The B/C ratio below 50 MeV/nuc measured at V1 exceeds the predictions of both propagation models by as much as 3 sigma in the data measurement errors.

[5]  arXiv:1711.08021 [pdf, other]
Title: Electrostatic stability of electron-positron plasmas in dipole geometry
Subjects: Plasma Physics (physics.plasm-ph)

The electrostatic stability of electron-positron plasmas is investigated in the point-dipole and Z-pinch limits of dipole geometry. The kinetic dispersion relation for sub-bounce-frequency instabilities is derived and solved. For the zero-Debye-length case, the stability diagram is found to exhibit singular behavior. However, when the Debye length is non-zero, a fluid mode appears, which resolves the observed singularity, and also demonstrates that both the temperature and density gradients can drive instability. It is concluded that a finite Debye length is necessary to determine the stability boundaries in parameter space. Landau damping is investigated at scales sufficiently smaller than the Debye length, where instability is absent.

[6]  arXiv:1711.08033 [pdf]
Title: Fluorescence branching ratios and magnetic tuning of the visible spectrum of SrOH
Comments: Article: 37 pages of text; 4 tables and 9 figures; Supplemental material: 4 tables and description of DFT calulation
Subjects: Chemical Physics (physics.chem-ph)

The magnetic tuning of the low rotational levels in the Xsigma+(0,0,0), Api(0,0,0), and Bsigma+ (0,0,0) electronic states of strontium hydroxide, SrOH, have been experimentally investigated using high resolution optical Zeeman spectroscopy of a cold molecular beam sample. The observed Zeeman shifts and splittings are successfully modeled using a traditional effective Hamiltonian approach to account for the interaction between the Api and Bsigma+ states. The determined magnetic g-factors for the Xsigma+, Api , and Bsigma+ states are compared to those predicted by perturbation theory. The dispersed fluorescence resulting from laser excitation of rotationally resolved branch features of the Bsigma+ (0,0,0)<Xsigma+(0,0,0) Api(0,0,0)< Xsigma+(0,0,0) transitions have been recorded and analyzed. The measured fluorescence branching ratios are compared with Franck-Condon calculations. The required bending motion wave functions are derived using a discrete variable representation (DVR) method. Implications for laser slowing and magneto-optical trapping experiments for SrOH are described.

[7]  arXiv:1711.08067 [pdf]
Title: Continuous regional trace gas source attribution using a field-deployed dual frequency comb spectrometer
Comments: 9 pages, 4 main text figures, 2 main text tables, 5 SI figures
Subjects: Atmospheric and Oceanic Physics (physics.ao-ph)

Identification and quantification of trace gas sources is a major challenge for understanding and regulating air quality and greenhouse gas emissions. Current approaches either provide continuous but localized monitoring, or quasi-instantaneous 'snapshot-in-time' regional monitoring. There is a need for emissions detection that provides both continuous and regional coverage, because sources and sinks can be episodic and spatially variable. We field deploy a dual frequency comb laser spectrometer for the first time, enabling an observing system that provides continuous detection of trace gas sources over multiple-square-kilometer regions. Field tests simulating methane emissions from oil and gas production demonstrate detection and quantification of a 1.6 g min^-1 source (approximate emissions from a small pneumatic valve) from a distance of 1 km, and the ability to discern two leaks among a field of many potential sources. The technology achieves the goal of detecting, quantifying, and attributing emissions sources continuously through time, over large areas, and at emissions rates ~1000x lower than current regional approaches. It therefore provides a useful tool for monitoring and mitigating undesirable sources and closes a major information gap in the atmospheric sciences.

[8]  arXiv:1711.08084 [pdf, ps, other]
Title: A correction scheme for two-way coupled point-particle simulations on anisotropic grids
Comments: 25 pages, 10 figures and 4 tables
Subjects: Fluid Dynamics (physics.flu-dyn)

The accuracy of Lagrangian point-particle models for simulation of particle-laden flows may degrade when the particle and fluid momentum equations are two-way coupled. In these cases the fluid velocity at the location of the particle, which is often used as an estimation of the undisturbed velocity, is altered by the presence of the particle, modifying the slip velocity and producing an erroneous prediction of coupling forces between fluid and particle. In this article, we propose a correction scheme to eliminate this error and predict the undisturbed fluid velocity accurately. Conceptually, in this method, the computation cell is treated as a solid object immersed in the fluid that is subjected to the two-way coupling force and dragged at a velocity that is identical to the disturbance created by the particle. The proposed scheme is generic as it can be applied to unstructured grids with arbitrary geometry and particles that have different size and density. At its crudest form for isotropic grids, the present correction scheme reduces to dividing the Stokes drag by $1 - 0.75\Lambda$, where $\Lambda$ is the ratio of the particle diameter to the grid size. The accuracy of the proposed scheme is evaluated by comparing the computed settling velocity of individual and pair of particles under gravity on anisotropic rectilinear grids against analytical solutions. This comparison shows up to two orders of magnitude reduction in error in cases where the particle is up to 5 times larger than the grid that may have an aspect ratio of over 10. Furthermore, a comparison against the particle-resolved simulation of decaying turbulence demonstrates the excellent accuracy of the proposed scheme.

[9]  arXiv:1711.08092 [pdf]
Title: Analytic solution for cylindrical beam position monitors with narrow striplines or small buttons
Comments: 20 pages. 17 figures
Subjects: Accelerator Physics (physics.acc-ph)

A simple, analytically correct algorithm is developed for calculating pencil beam coordinates using the signals from an ideal cylindrical beam position monitor (BPM) with four pickup electrodes (PUEs) of infinitesimal widths. The algorithm is then applied to simulations of realistic BPMs with finite width PUEs. Surprisingly small deviations are found. Simple empirically determined correction terms reduce the deviations even further. Finally, the algorithm is used to study the impact of beam-size upon the precision of BPMs in the non-linear region. As an example of the data acquisition speed advantage, a FPGA-based BPM readout implementation of the new algorithm has been developed and characterized.

[10]  arXiv:1711.08111 [pdf, ps, other]
Title: An perturbation-iteration method for multi-peak solitons in nonlocal nonlinear media
Subjects: Optics (physics.optics)

An perturbation-iteration method is developed for the computation of the Hermite-Gaussian-like solitons with arbitrary peak numbers in nonlocal nonlinear media. This method is based on the perturbed model of the Schr\"{o}dinger equation for the harmonic oscillator, in which the minimum perturbation is obtained by the iteration. This method takes a few tens of iteration loops to achieve enough high accuracy, and the initial condition is fixed to the Hermite-Gaussian function. The method we developed might also be extended to the numerical integration of the Schr\"{o}dinger equations in any type of potentials.

[11]  arXiv:1711.08120 [pdf, other]
Title: Sorting photons by radial quantum number
Subjects: Optics (physics.optics); Quantum Physics (quant-ph)

The Laguerre-Gaussian (LG) modes constitute a complete basis set for representing the transverse structure of a {paraxial} photon field in free space. Earlier workers have shown how to construct a device for sorting a photon according to its azimuthal LG mode index, which describes the orbital angular momentum (OAM) carried by the field. In this paper we propose and demonstrate a mode sorter based on the fractional Fourier transform (FRFT) to efficiently decompose the optical field according to its radial profile. We experimentally characterize the performance of our implementation by separating individual radial modes as well as superposition states. The reported scheme can, in principle, achieve unit efficiency and thus can be suitable for applications that involve quantum states of light. This approach can be readily combined with existing OAM mode sorters to provide a complete characterization of the transverse profile of the optical field.

[12]  arXiv:1711.08127 [pdf, ps, other]
Title: Automatic differentiation in quantum chemistry with an application to fully variational Hartree-Fock
Subjects: Chemical Physics (physics.chem-ph)

Automatic Differentiation (AD) is a powerful tool that allows calculating derivatives of implemented algorithms with respect to all of their parameters up to machine precision, without the need to explicitly add any additional functions. Thus, AD has great potential in quantum chemistry, where gradients are omnipresent but also difficult to obtain, and researchers typically spend a considerable amount of time finding suitable analytical forms when implementing derivatives. Here, we demonstrate that automatic differentiation can be used to compute gradients with respect to any parameter throughout a complete quantum chemistry method. We implement DiffiQult, a fully autodifferentiable Hartree-Fock (HF) algorithm, which serves as a proof-of-concept that illustrates the capabilities of AD for quantum chemistry. We leverage the obtained gradients to optimize the parameters of one-particle basis sets in the context of the floating Gaussian framework.

[13]  arXiv:1711.08134 [pdf, other]
Title: Analysis of the fine structure of HF ground backscatter and ionospheric scatter signals based on EKB radar data
Comments: 24 pages, 8 figures, to be submitted to JASTP
Subjects: Geophysics (physics.geo-ph); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)

The analysis was carried out of the scattered signal in the cases of ground backscatter and ionospheric scatter. The analysis is based on the data of the decameter coherent EKB ISTP SB RAS radar. In the paper the signals scattered in each sounding run were analysed before their statistical averaging. Based on the analysis and on previously studied mechanisms, a model is constructed for ionospheric scatter and ground backscatter signals. Within the framework of the Bayesian approach and based on a large amount of the data the technique and algorithm for separating these two types of signals are constructed. The statistical analysis of the results was carried out based on the EKB ISTP SB RAS data.

[14]  arXiv:1711.08149 [pdf, other]
Title: Accurate Real Time Localization Tracking in A Clinical Environment using Bluetooth Low Energy and Deep Learning
Subjects: Medical Physics (physics.med-ph); Learning (cs.LG)

Deep learning has started to revolutionize several different industries, and the applications of these methods in medicine are now becoming more commonplace. This study focuses on investigating the feasibility of tracking patients and clinical staff wearing Bluetooth Low Energy (BLE) tags in a radiation oncology clinic using artificial neural networks (ANNs) and convolutional neural networks (CNNs). The performance of these networks was compared to relative received signal strength indicator (RSSI) thresholding and triangulation. By utilizing temporal information, a combined CNN+ANN network was capable of correctly identifying the location of the BLE tag with an accuracy of 99.9%. It outperformed a CNN model (accuracy = 94%), a thresholding model employing majority voting (accuracy = 95%), and a triangulation classifier utilizing majority voting (accuracy = 91%). Future studies will seek to deploy this affordable real time location system in hospitals to improve clinical workflow, efficiency, and patient safety.

[15]  arXiv:1711.08152 [pdf]
Title: Parametric amplification and bidirectional invisibility in PT-symmetric time-Floquet systems
Subjects: Optics (physics.optics)

Parity-Time (PT) symmetric wave devices, which exploit balanced interactions between material gain and loss, exhibit extraordinary properties, including lasing and flux-conserving scattering processes. In a seemingly different research field, periodically driven systems, also known as time-Floquet systems, have been widely studied as a relevant platform for reconfigurable active wave control and manipulation. In this article, we explore the connection between PT-symmetry and parametric time-Floquet systems. Instead of relying on material gain, we use parametric amplification by considering a time-periodic modulation of the refractive index at a frequency equal to twice the incident signal frequency. We show that the scattering from a simple parametric slab, whose dynamics follow Mathieu equation, can be described by a PT-symmetric scattering matrix, whose PT-breaking threshold corresponds to the Mathieu instability threshold. By combining different parametric slabs modulated out-of-phase, we create PT-symmetric time-Floquet systems that feature exceptional scattering properties, such as CPA/Laser operation and bidirectional invisibility. These bidirectional properties, rare for regular PT-symmetric systems, are related to a compensation of parametric amplification due to multiple scattering between two parametric systems modulated with a phase difference.

[16]  arXiv:1711.08154 [pdf]
Title: Laboratory simulation of field aligned currents in experiment on laser-produced plasma interacting with magnetic dipole
Journal-ref: Shaikhislamov et al. Laboratory simulation of field aligned currents in an experiment on laser-produced plasma interacting with a magnetic dipole. Plasma Physics and Controlled Fusion, 51(10), 105005, 2009
Subjects: Plasma Physics (physics.plasm-ph)

In an experiment on a magnetic dipole interacting with a laser-produced plasma the generation of an intense field aligned current (FAC) system was observed for the first time in a laboratory. The detailed measurements of the total value and local current density, of the magnetic field at the poles and in the equatorial magnetopause, and particular features of electron motion in the current channels revealed its similarity to the Region-1 current system in the Earth magnetosphere. Such currents were found to exist only if they can close via conductive cover of the dipole. Comparison of conductive and dielectric cases revealed specific magnetic features produced by FACand their connection with electric potential generated in the equatorial part of the magnetopause. To interpret the data we consider a model of electric potential generation in the boundary layer which agrees with experiment and with measurements of the Earth transpolar potential in the absence of an interplanetary magnetic field as well. The results could be of importance for the investigation of Mercury as a magnetic disturbance due to FAC could be especially large because of the small size of the Hermean magnetosphere.

[17]  arXiv:1711.08157 [pdf]
Title: Laboratory experiment on region-1 field-aligned current and its origin in low-latitude boundary layer
Journal-ref: Shaikhislamov et al. Laboratory experiment on region-1 field-aligned current and its origin in the low-latitude boundary layer. Plasma Physics and Controlled Fusion, 53(3), 035017, 2011
Subjects: Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)

In previous experiments by the authors on a magnetic dipole interacting with a laser-produced plasma the generation of an intense field-aligned current (FAC) system on terrella poles was observed. In this paper the question of the origin of these currents in a low-latitude boundary layer of magnetosphere is investigated. Experimental evidence of such a link was obtained by measurements of the magnetic field generated by tangential drag and sheared stress. This specific azimuthal field was found to have quadruple symmetry and local maxima inside the magnetosphere adjacent to the boundary layer. Cases of metallic and dielectric dipole covers modeling good conductive and non-conductive ionosphere revealed that the presence or absence of FACs results in different amplitudes and spatial structures of the sheared field. The current associated with the azimuthal field flows upward at the dawnside, and toward the equator plane at the duskside. It was found to coincide by direction and to correspond by amplitude to a total cross-polar current measured independently. The results suggest that compressional and Alfven waves are responsible for FAC generation. The study is most relevant to FACgeneration in the magnetospheres of Earth and Mercury following pressure jumps in solar wind.

[18]  arXiv:1711.08158 [pdf]
Title: Twin GEM-TPC Prototype (HGB4) Beam Test at GSI and Jyväskylä - a Development for the Super-FRS at FAIR
Comments: 5 pages, 8 figures
Journal-ref: Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop (NSS/MIC/RTSD), 2016
Subjects: Instrumentation and Detectors (physics.ins-det)

The FAIR[1] facility is an international accelerator centre for research with ion and antiproton beams. It is being built at Darmstadt, Germany as an extension to the current GSI research institute. One major part of the facility will be the Super-FRS[2] separator, which will be include in phase one of the project construction. The NUSTAR experiments will benefit from the Super-FRS, which will deliver an unprecedented range of radioactive ion beams (RIB). These experiments will use beams of different energies and characteristics in three different branches; the high-energy which utilizes the RIB at relativistic energies 300-1500 MeV/u as created in the production process, the low-energy branch aims to use beams in the range of 0-150 MeV/u whereas the ring branch will cool and store beams in the NESR ring. The main tasks for the Super-FRS beam diagnostics chambers will be for the set up and adjustment of the separator as well as to provide tracking and event-by-event particle identification. The Helsinki Institute of Physics, and the Detector Laboratory and Experimental Electronics at GSI are in a joint R&D of a GEM-TPC detector which could satisfy the requirements of such tracking detectors, in terms of tracking efficiency, space resolution, count rate capability and momenta resolution. The current prototype, which is the generation four of this type, is two GEM-TPCs in twin configuration inside the same vessel. This means that one of the GEM-TPC is flipped on the middle plane w.r.t. the other one. This chamber was tested at Jyv\"askyl\"a accelerator with protons projectiles and at GSI with Uranium, fragments and Carbon beams during this year 2016.

[19]  arXiv:1711.08170 [pdf]
Title: Detection of Molecular Scattering Field by Polarization Analysis of Sky Background During the Transitive Twilight and Temperature Measurements near the Stratopause
Comments: 13 pages, 6 figures
Subjects: Atmospheric and Oceanic Physics (physics.ao-ph)

The simplest version of the method of detection of single molecular scattering basing on the polarization measurements of the twilight sky background by all-sky cameras is considered. The method can be used during the transitive twilight (solar zenith angles 94-98 degrees), when effective single scattering takes place in upper stratosphere and lower mesosphere. The application of the method to the multi-year measurements in the vicinity of Moscow and Apatity allows determination of temperature of these atmospheric layers and estimation of contribution and properties of multiple scattering during the transitive twilight period.

[20]  arXiv:1711.08192 [pdf]
Title: Characterization of nonlinear effects in edge filters
Comments: 3 pages
Subjects: Optics (physics.optics)

A specially designed and produced edge filter with pronounced nonlinear effects is carefully characterized. The nonlinear effects are estimated at the intensities close to the laser-induced damage.

[21]  arXiv:1711.08197 [pdf, other]
Title: Coupled forward-backward trajectory approach for non-equilibrium electron-ion dynamics
Subjects: Chemical Physics (physics.chem-ph)

We introduce a simple ansatz for the wavefunction of a many-body system based on coupled forward and backward-propagating semiclassical trajectories. This method is primarily aimed at, but not limited to, treating nonequilibrium dynamics in electron-phonon systems. The time-evolution of the system is obtained from the Euler-Lagrange variational principle, and we show that this ansatz yields Ehrenfest mean field theory in the limit that the forward and backward trajectories are orthogonal, and in the limit that they coalesce. We investigate accuracy and performance of this method by simulating electronic relaxation in the spin-boson model and the Holstein model. Although this method involves only pairs of semiclassical trajectories, it shows a substantial improvement over mean field theory, capturing quantum coherence of nuclear dynamics as well as electron-nuclear correlations. This improvement is particularly evident in nonadiabatic systems, where the accuracy of this coupled trajectory method extends well beyond the perturbative electron-phonon coupling regime. This approach thus provides an attractive route forward to the ab-initio description of relaxation processes, such as thermalization, in condensed phase systems.

[22]  arXiv:1711.08203 [pdf, other]
Title: Theory of metasurface based perfect absorbers
Subjects: Optics (physics.optics)

Based on an analytic approach, we present a theoretical review on the absorption, scattering, and extinction of both dipole scatterers and regular arrays composed of such scatterers i.e., metasurfaces. Besides offering a tutorial by outlining the maximum absorption limit for electrically/magnetically resonant dipole particles/metasurfaces, we give an educative analytical approach to their analysis. Moreover, we put forward the analysis of two known alternatives in providing perfect absorbers out of electrically and or magnetically resonant metasurfaces; one is based on the simultaneous presence of both electric and magnetic responses in so called Huygens metasurfaces while the other is established upon the presence of a back reflector in so called Salisbury absorbers. Our work is supported by several numerical examples to clarify the discussions in each stage.

[23]  arXiv:1711.08212 [pdf, other]
Title: Shockwave-assisted laser filament conductivity
Comments: 8 pages, 4 figures
Journal-ref: Applied Physics Letters 111, 211103 (2017);
Subjects: Optics (physics.optics); Plasma Physics (physics.plasm-ph)

We investigate the influence of ultrashort laser filaments on high-voltage discharges and spark-free unloading at various repetition rates and wind conditions. For electric fields well below, close to and above the threshold for discharges, we respectively observe remote spark-free unloading, discharge suppression, and discharge guiding. These effects rely on an indirect consequence of the thermal deposition, namely the fast dilution of the ions by the shockwave triggered by the filament at each laser shot. This dilution drastically limits recombination and increases the plasma channel conductivity that can still be non-negligible after tens or hundreds of milliseconds. As a result, the charge flow per pulse is higher at low repetition rates.

[24]  arXiv:1711.08248 [pdf, other]
Title: On the physical mechanism of three-wave instabilities -- resonance between positive- and negative-action modes
Comments: 13 pages, 3 figures
Subjects: Plasma Physics (physics.plasm-ph); Optics (physics.optics)

Three-wave instability is a fundamental process that has important applications in many branches of physics. It is widely accepted that the resonant condition $\omega_{z}\approx\omega_{x}+\omega_{y}$ for participating waves is the criteria for the onset of the instability. We show that this condition is neither sufficient nor necessary, instead, the exact criteria for the onset of the instability is that a positive-action mode resonates with a negative-action mode. This mechanism is imposed by the topology and geometry of the spectral space. Guided by this new theory, two additional instability bands previously unknown are discovered.

[25]  arXiv:1711.08260 [pdf, other]
Title: Genetic noise mechanism for power-law switching in bacterial flagellar motors
Comments: 6 pages, 4 figures
Subjects: Biological Physics (physics.bio-ph); Molecular Networks (q-bio.MN); Subcellular Processes (q-bio.SC)

Switching of the direction of flagella rotations is the key control mechanism governing the chemotactic activity of E. coli and many other bacteria. Power-law distributions of switching times are most peculiar because their emergence cannot be deduced from simple thermodynamic arguments. Recently it was suggested that by adding finite-time correlations into Gaussian fluctuations regulating the energy height of barrier between the two rotation states, one can generate a power-law switching statistics. By using a simple model of a regulatory pathway, we demonstrate that the required amount of correlated `noise' can be produced by finite number fluctuations of reacting protein molecules, a condition common to the intracellular chemistry. The corresponding power-law exponent appears as a tunable characteristic controlled by parameters of the regulatory pathway network such as equilibrium number of molecules, sensitivities, and the characteristic relaxation time.

[26]  arXiv:1711.08262 [pdf, other]
Title: MMS observation of asymmetric electron-scale reconnection driven by 3-D electron pressure divergence
Comments: Submitted to JGR Space Physics
Subjects: Space Physics (physics.space-ph)

We identify a dayside electron diffusion region (EDR) encountered by the Magnetospheric Multiscale (MMS) mission and estimate the terms in generalized Ohm's law that controled energy conversion near the X-point. MMS crossed the moderate-shear ($\sim$130$^\circ$) magnetopause southward of the exact X-point. MMS likely entered the magnetopause far from the X-point, outside the EDR, as the size of the reconnection layer was less than but comparable to the magnetosheath proton gyro-radius, and also as anisotropic gyrotropic "outflow" crescent electron distributions were observed. MMS then approached the X-point, where all four spacecraft simultaneously observed signatures of the EDR, e.g., an intense out-of-plane electron current, moderate electron agyrotropy, intense electron anisotropy, non-ideal electric fields, non-ideal energy conversion, etc. We find that the electric field associated with the non-ideal energy conversion is (a) well described by the sum of the electron inertial and pressure divergence terms in generalized Ohms law though (b) the pressure divergence term dominates the inertial term by roughly a factor of 5:1, (c) both the gyrotropic and agyrotropic pressure forces contribute to energy conversion at the X-point, and (d) both out-of-the-reconnection-plane gradients ($\partial/\partial M$) and in-plane ($\partial/\partial L,N$) in the pressure tensor contribute to energy conversion near the X-point. This indicates that this EDR had some electron-scale structure in the out-of-plane direction during the time when (and at the location where) the reconnection site was observed.

[27]  arXiv:1711.08290 [pdf]
Title: A compact superconducting nanowire memory element operated by nanowire cryotrons
Subjects: Applied Physics (physics.app-ph)

A superconducting loop stores persistent current without any ohmic loss, making it an ideal platform for energy efficient memories. Conventional superconducting memories use an architecture based on Josephson junctions (JJs) and have demonstrated access times less than 10 ps and power dissipation as low as $10^{-19}$ J. However, their scalability has been slow to develop due to the challenges in reducing the dimensions of JJs and minimizing the area of the superconducting loops. In addition to the memory itself, complex readout circuits require additional JJs and inductors for coupling signals, increasing the overall area. Here, we have demonstrated a superconducting memory based solely on lithographic nanowires. The small dimensions of the nanowire ensure that the device can be fabricated in a dense area in multiple layers, while the high kinetic inductance makes the loop essentially independent of geometric inductance, allowing it to be scaled down without sacrificing performance. The memory is operated by a group of nanowire cryotrons patterned alongside the storage loop, enabling us to reduce the entire memory cell to 3 {\mu}m $\times $ 7 {\mu}m in our proof-of-concept device. In this work we present the operation principles of a superconducting nanowire memory (nMem) and characterize its bit error rate, speed, and power dissipation.

[28]  arXiv:1711.08307 [pdf, other]
Title: Photon detection system for ProtoDUNE dual phase
Authors: Clara Cuesta (on behalf of DUNE collaboration)
Comments: 6 pages, 4 figures, LIDINE 2017 proceedings, submitted to the Proceedings Section of JINST
Subjects: Instrumentation and Detectors (physics.ins-det)

The Deep Underground Neutrino Experiment (DUNE) is a 40-kton underground liquid argon time-projection-chamber (LAr TPC) detector, for long-baseline neutrino oscillation studies and for neutrino astrophysics and nucleon decay searches. Photon detector systems embedded within the LAr TPC add precise timing capabilities for non-beam events. The ProtoDUNE dual phase detector will consist of a 6x6x6 m3 liquid argon time-projection chamber placed at CERN and the light readout will be formed by 8-inch cryogenic photomultipliers from Hamamatsu. The characterization of the 36 photomultipliers, the base design, and the light calibration system are described. In addition, preliminary results from a 3x1x1 m3 LAr double phase detector operating at CERN are presented.

[29]  arXiv:1711.08321 [pdf, ps, other]
Title: The Eightfold Way for Composite Quarks and Leptons
Authors: J.L. Chkareuli
Comments: 20 pages
Subjects: General Physics (physics.gen-ph)

The $L$-$R$ symmetric composite model for quarks and leptons where constituent preons are bound by the $SO(n)_{L}\times SO(n)_{R}$ gauge forces is reconsidered. We find that just the eight left-handed and right-handed preons, their local metaflavor symmetry $SU(8)_{MF}$ and accompanying global chiral symmetry $SU(8)_{L}\times SU(8)_{R}$ may determine physical world at small distances. This result for an admissible number of preons filling the fundamental multiplet of some $SU(N)_{MF}$ symmetry group appears as a solution to the 't Hooft's anomaly matching condition precisely for $N=8$, provided that this condition is satisfied separately for the $L$-preon and $R $-preon composites which form individually a single multiplet of the $SU(N)$ rather than a set of its multiplets. We next show that an appropriate $L$-$R$ symmetry violation reduces the vectorlike $SU(8)$ theory initially emerged for the identical $L$-preon and $R$-preon composites down to the conventional $SU(5)$ GUT with an extra local family symmetry $SU(3)_{F}$ and three standard generations of quarks and leptons. Though the tiny radius of compositeness for universal preons composing both quarks and leptons makes it impossible to immediately confirm their composite nature, a few special $% SU(5)\times SU(3)_{F}$ multiplets of extra composite fermions located at the scales from $O(1)$ $TeV$ up to the Planck mass scale predicted by the theory may appear of actual experimental interest. Some of them can be directly observed, the others populate the $SU(5)$ GUT desert. Due to their mixing with ordinary quark-lepton families there may arise a marked violation of unitarity in the mass matrices for leptons and down quarks depending on the interplay between the compositeness scale and scale of the family symmetry $% SU(3)_{F}$.

[30]  arXiv:1711.08326 [pdf, ps, other]
Title: Anisotropic extension of Finch and Skea stellar model
Comments: To appear in Astrophys. Space Sci
Subjects: General Physics (physics.gen-ph)

In this paper, the spacetime geometry of Finch and Skea [Class. Quantum Grav., 6 (1989) 467] has been utilized to obtain closed-form solutions for a spherically symmetric anisotropic matter distribution. By examining its physical admissibility, it has been shown that the class of solutions can be used as viable models for observed pulsars. In particular, a specific class of solutions can be used as an `anisotropic switch' to examine the impact of anisotropy on the gross physical properties of a stellar configuration. Accordingly, the mass-radius relationship has been analyzed.

[31]  arXiv:1711.08338 [pdf, other]
Title: Accelerated cosmos in a non-extensive setup
Comments: Accepted by Phys. Rev. D
Subjects: General Physics (physics.gen-ph)

Here, we consider a flat FRW universe whose its horizon entropy meets the R\'enyi entropy of non-extensive systems. In our model, the ordinary energy-momentum conservation law is not always valid. By applying the Clausius relation as well as the Cai-Kim temperature to the apparent horizon of a flat FRW universe, we obtain modified Friedmann equations. Fitting the model to the observational data on current accelerated universe, some values for the model parameters are also addressed. Our study shows that the current accelerating phase of universe expansion may be described by a geometrical fluid, originated from the non-extensive aspects of geometry, which models a varying dark energy source interacting with matter field in the Rastall way. Moreover, our results indicate that the probable non-extensive features of spacetime may also be used to model a varying dark energy source which does not interact with matter field, and is compatible with the current accelerated phase of universe.

[32]  arXiv:1711.08346 [pdf, ps, other]
Title: High-order corrections to tauon mass in a microscopic cosmological model
Authors: Vo Van Thuan
Comments: For the International Workshop Belle-II and Vietnam-2017
Subjects: General Physics (physics.gen-ph)

According to our microscopic cosmological model, masses of charged leptons are induced by curvatures of hyper-spherical surfaces embedded in a 3D time-like subspace, leading to a solution of the lepton mass hierarchy problem and to a prediction of tauon mass for the first approximation. In the present study, for finest-tuning higher order approximations, there are some corrections added to higher curvatures by contributions from lower ones. In the result, the calculation in the third approximation $m_{\tau}(theor)=1776.40$ MeV fits the experimental tauon mass $m_{\tau}(exp)=1776.82(\pm.16)$ MeV within $0.024\%$ of precision, reaching a fairly passable consistency better than $3\sigma$. On one side, it implies that for a firm consistency, a hyper-fine adjustment of calculation by some additional mechanism is needed. On the other side, our theoretical quantity demonstrates an explicit physical interpretation, which is in opposite to another theoretical calculation with a wonderful predictability by the empirical Koide formula $m_\tau(Koide)=1776.97$ MeV, i.e. within a deviation less than $1\sigma$, unfortunately, being physically unexplained. In the circumstances, a new attempt for upgrading experimental accuracy of tauon mass is desirable.

[33]  arXiv:1711.08358 [pdf, other]
Title: Mechanistic constitutive model for wormlike micelle solutions with flow-induced structure formation
Subjects: Fluid Dynamics (physics.flu-dyn)

We present a tensor constitutive model for predicting stress and flow-induced structure formation in dilute wormlike micellar solutions. The micellar solution is treated as a dilute suspension of rigid Brownian rods whose length varies dynamically. Consistent with the mechanism presented by Turner and Cates [J. Phys.:~Condens. Matter 4, 3719 (1992)], flow-induced alignment of the rods is assumed to promote increase of rod length that corresponds to the formation of flow-induced structures observed in experiments. At very high deformation rate, hydrodynamic stresses causes the rod length to decrease. These mechanisms are implemented in a phenomenological equation governing the evolution of rod length, with the number density of rods appropriately modified to ensure conservation of surfactant mass. The model leads first to an increase in both shear and extensional viscosity as deformation rate increases and then to a decrease at higher rates. If the rate constant for flow-induced rod growth is sufficiently large, the model predicts a multivalued relation between stress and deformation rate in both shear and uniaxial extension. Predictions for shear and extensional flow at steady state are in reasonable agreement with experimental results. By design, the model is simple enough to serve as a tractable constitutive relation for computational fluid dynamics studies.

[34]  arXiv:1711.08361 [pdf, ps, other]
Title: Experimental Evidence for Selection Rules in Multiphoton Double Ionization of Helium
Authors: K. Henrichs (1), S. Eckart (1), A. Hartung (1), D. Trabert (1), J. Rist (1), H. Sann (1), M. Pitzer (2), M. Richter (1), H. Kang (1 and 3), M. S. Schöffler (1), M. Kunitski (1), T. Jahnke (1), R. Dörner (1) ((1) Institut für Kernphysik, J. W. Goethe-Universität Frankfurt am Main, Germany, (2) Institut für Physik, Universität Kassel, Germany, (3) State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, China)
Comments: 5 pages, 3 figures, submitted to Phys. Rev. Lett
Subjects: Atomic Physics (physics.atom-ph)

We report on the observation of phase space modulations in the correlated electron emission after strong field double ionization of helium using laser pulses with a wavelength of 394~nm and an intensity of $3\cdot10^{14}$W/cm$^2$. Those modulations are identified as direct results of quantum mechanical selection rules predicted by many theoretical calculations. They only occur for an odd number of absorbed photons. By that we attribute this effect to the parity of the continuum wave function.

[35]  arXiv:1711.08367 [pdf]
Title: Drift-induced Unidirectional Graphene Plasmons
Comments: 22 pages, under review
Subjects: Optics (physics.optics)

Nonreciprocal photonic devices enable "one-way" light flows and are essential building blocks of optical systems. Here, we suggest a novel paradigm to break reciprocity and achieve unidirectional subwavelength light propagation fully compatible with modern all-photonic highly-integrated systems. It is theoretically demonstrated that a graphene sheet biased with a constant drift electric current has a strong nonreciprocal tunable response and, in particular, supports one-way surface plasmon polaritons immune to backscattering from defects and obstacles. Remarkably, it is found that the drift-current biasing may boost the propagation length of the graphene plasmons by more than 100%. Our findings open new inroads in nonreciprocal photonics and offer a new opportunity to control the flow of light with one-atom thick nonreciprocal devices.

[36]  arXiv:1711.08384 [pdf, ps, other]
Title: Envelope modulations of kinetic plasma waves: A general framework
Subjects: Plasma Physics (physics.plasm-ph)

The general framework of envelope modulations for plasma turbulence in the presence of strong magnetic fields is discussed. It is shown that the problem can be formulated using a functional which is equivalent to the plasma dielectric function for monochromatic waves. Therefore expanding around its linear wave solutions, one can describe the weakly nonlinear evolution of waves. The resulting "quasi-linear" dielectric tensor, can describe the evolution of small scale fluctuations advected and modulated by background flows and corrugations, as well as the evolution of the large scale flows driven by small scales. As a concrete example of the framework, gyrokinetic evolution of zonal flows and drift waves is considered and the resulting nonlinear Schr\"odinger equation is derived.

[37]  arXiv:1711.08429 [pdf, other]
Title: An ultrafast electro-optic light source with sub-cycle precision
Subjects: Optics (physics.optics)

Controlling femtosecond optical pulses with temporal precision better than one cycle of the carrier field has a profound impact on measuring and manipulating interactions between light and matter. We explore pulses that are carved from a continuous-wave laser via electro-optic modulation and realize the regime of sub-cycle optical control without a mode-locked resonator. Our ultrafast source, with a repetition rate of 10 GHz, is derived from an optical-cavity-stabilized laser and a microwave-cavity-stabilized electronic oscillator. Sub-cycle timing jitter of the pulse train is achieved by coherently linking the laser and oscillator through carrier-envelope phase stabilization enabled by a photonic-chip supercontinuum that spans up to 1.9 octaves across the near infrared. Moreover, the techniques we report are relevant for other ultrafast lasers with repetition rates up to 30 GHz and may allow stable few-cycle pulses to be produced by a wider range of sources.

[38]  arXiv:1711.08440 [pdf, ps, other]
Title: Self-adjustment of a nonlinear lasing mode to a pumped area in a two-dimensional microcavity
Comments: 8 pages, 10 figures
Journal-ref: Photonics Research, Vol. 5, No. 6, pp. B47-B53 (2017)
Subjects: Optics (physics.optics); Chaotic Dynamics (nlin.CD)

We numerically performed wave dynamical simulations based on the Maxwell-Bloch (MB) model for a quadrupole-deformed microcavity laser with spatially selective pumping. We demonstrate the appearance of an asymmetric lasing mode whose spatial pattern violates both the x- and y-axes mirror symmetries of the cavity. Dynamical simulations revealed that a lasing mode consisting of a clockwise or counterclockwise rotating-wave component is a stable stationary solution of the MB model. From the results of a passive-cavity mode analysis, we interpret these asymmetric rotating-wave lasing modes by the locking of four nearly degenerate passive-cavity modes. For comparison, we carried out simulations for a uniform pumping case and found a different locking rule for the nearly degenerate modes. Our results demonstrate a nonlinear dynamical mechanism for the formation of a lasing mode that adjusts its pattern to a pumped area.

[39]  arXiv:1711.08444 [pdf, other]
Title: THz electrical writing speed in an antiferromagnetic memory
Subjects: Applied Physics (physics.app-ph)

The speed of writing of state-of-the-art ferromagnetic memories is physically limited by an intrinsic GHz threshold. Recently, an alternative research direction has been initiated by realizing memory devices based on antiferromagnets in which spin directions periodically alternate from one atomic lattice site to the next. In our work we experimentally demonstrate at room temperature that the speed of reversible electrical writing in a memory device can be scaled up to THz using an antiferromagnet. Efficient current-induced spin-torque mechanism is responsible for the switching in our memory devices throughout the twelve orders of magnitude range of writing speeds from Hz to THz. Our work opens the path towards the development of memory-logic technology reaching the elusive THz band.

[40]  arXiv:1711.08445 [pdf, other]
Title: The Peridynamic Stress Tensors and the Non-local to Local Passage
Authors: Petr Pelech
Comments: 20 pages, 4 figures
Subjects: Classical Physics (physics.class-ph)

We re-examine the notion of stress in peridynamics. Based on the idea of traction we define two new peridynamic stress tensors $\mathbf{P}^{\mathbf{y}}$ and $\mathbf{P}$ which stand, respectively, for analogues of the Cauchy and 1st Piola-Kirchhoff stress tensors from classical elasticity. We show that the tensor $\mathbf{P}$ differs from the earlier defined peridynamic stress tensor $\nu$, though their divergence is equal. We address the question of symmetry of the tensor $\mathbf{P}^{\mathbf{y}}$ which prove to be symmetric in case of bond-based peridynamics. As opposed to the inverse Piola transform of $\nu$ (corresponding to the analogue of Cauchy stress tensor) which fails to be symmetric in general. We also derive a general formula of the force-flux in peridynamics and compute the limit of $\mathbf{P}$ for vanishing non-locality, denoted by $\mathbf{P}_0$. We show that this tensor $\mathbf{P}_0$ surprisingly coincides with the collapsed tensor $\nu_0$, a limit of the original tensor $\nu$. At the end, using this flux-formula, we suggest an explanation why the collapsed tensor $\mathbf{P}_0$ (and hence $\nu_0$) can be indeed identified with the 1st Piola-Kirchhoff stress tensor.

Cross-lists for Thu, 23 Nov 17

[41]  arXiv:1711.08044 (cross-list from astro-ph.HE) [pdf, other]
Title: Photonuclear Reactions in Lightning Discovered from Detection of Positrons and Neutrons
Authors: Teruaki Enoto (1), Yuuki Wada (2 and 3), Yoshihiro Furuta (2), Kazuhiro Nakazawa (2), Takayuki Yuasa (4), Kazufumi Okuda (2), Kazuo Makishima (3), Mitsuteru Sato (5), Yousuke Sato (6), Toshio Nakano (3), Daigo Umemoto (3), Harufumi Tsuchiya (7) ((1) Kyoto University, (2) The University of Tokyo, (3) RIKEN, (4) Singapore, (5) Hokkaido University, (6) Nagoya University, (7) JAEA)
Comments: This manuscript was submitted to Nature Letter on July 30, 2017, and the original version that has not undergo the peer review process. See the accepted version at Nature website, published on the issue of November 23, 2017 with the revised title "photonuclear reaction triggered by lightning discharge"
Journal-ref: Nature Letter, the issue of November 23, 2017
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Atmospheric and Oceanic Physics (physics.ao-ph)

Lightning and thundercloud are the most dramatic natural particle accelerators on the Earth. Relativistic electrons accelerated by electric fields therein emit bremsstrahlung gamma rays, which have been detected at ground observations, by airborne detectors, and as terrestrial gamma-ray flashes (TGFs) from space. The energy of the gamma rays is sufficiently high to potentially invoke atmospheric photonuclear reactions 14N(gamma, n)13N, which would produce neutrons and eventually positrons via beta-plus decay of generated unstable radioactive isotopes, especially 13N. However, no clear observational evidence for the reaction has been reported to date. Here we report the first detection of neutron and positron signals from lightning with a ground observation. During a thunderstorm on 6 February 2017 in Japan, a TGF-like intense flash (within 1 ms) was detected at our monitoring sites 0.5-1.7 km away from the lightning. The subsequent initial burst quickly subsided with an exponential decay constant of 40-60 ms, followed by a prolonged line emission at about 0.511 megaelectronvolt (MeV), lasting for a minute. The observed decay timescale and spectral cutoff at about 10 MeV of the initial emission are well explained with de-excitation gamma rays from the nuclei excited by neutron capture. The centre energy of the prolonged line emission corresponds to the electron-positron annihilation, and hence is the conclusive indication of positrons produced after the lightning. Our detection of neutrons and positrons is unequivocal evidence that natural lightning triggers photonuclear reactions. No other natural event on the Earth is known to trigger photonuclear reactions. This discovery places lightning as only the second known natural channel on the Earth after the atmospheric cosmic-ray interaction, in which isotopes, such as 13C, 14C, and 15N, are produced.

[42]  arXiv:1711.08053 (cross-list from astro-ph.EP) [pdf, other]
Title: Exo-lightning radio emission: the case study of HAT-P-11b
Comments: Accepted to the Conference Proceedings of the 8th International Workshop on Planetary, Solar and Heliospheric Radio Emissions (PRE 8), held in Seggauberg near Leibnitz/Graz, Austria, October 25-27, 2016. 12 pages, 2 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR); Atmospheric and Oceanic Physics (physics.ao-ph); Geophysics (physics.geo-ph)

Lightning induced radio emission has been observed on solar system planets. Lecavelier des Etangs et al. [2013] carried out radio transit observations of the exoplanet HAT-P-11b, and suggested a tentative detection of a radio signal. Here, we explore the possibility of the radio emission having been produced by lightning activity on the exoplanet, following and expanding the work of Hodos\'an et al. [2016a]. After a summary of our previous work [Hodos\'an et al. 2016a], we extend it with a parameter study. The lightning activity of the hypothetical storm is largely dependent on the radio spectral roll-off, $n$, and the flash duration, $\tau_\mathrm{fl}$. The best-case scenario would require a flash density of the same order of magnitude as can be found during volcanic eruptions on Earth. On average, $3.8 \times 10^6$ times larger flash densities than the Earth-storms with the largest lightning activity is needed to produce the observed signal from HAT-P-11b. Combined with the results of Hodos\'an et al. [2016a] regarding the chemical effects of planet-wide thunderstorms, we conclude that future radio and infrared observations may lead to lightning detection on planets outside the solar system.

[43]  arXiv:1711.08059 (cross-list from cond-mat.quant-gas) [pdf, other]
Title: Coherent generation of photonic fractional quantum Hall states in a cavity and the search for anyonic quasiparticles
Comments: 11 pages + references, 10 figures. Supplemental Material currently available at this http URL
Subjects: Quantum Gases (cond-mat.quant-gas); Optics (physics.optics)

We present and analyze a protocol in which polaritons in a non-coplanar optical cavity form fractional quantum Hall states. We model the formation of these states and present techniques for subsequently creating anyons and measuring their fractional exchange statistics. In this protocol, we use a rapid adiabatic passage scheme to sequentially add polaritons to the system, such that the system is coherently driven from $n$ to $n+1$-particle Laughlin states. Quasiholes are created by slowly moving local pinning potentials in from outside the cloud. They are braided by dragging the pinning centers around one another, and the resulting phases are measured interferometrically. The most technically challenging issue with implementing our procedure is that maintaining adiabaticity and coherence requires that the two-particle interaction energy $V_0$ is sufficiently large compared to the single-polariton decay rate $\gamma$, $V_0 /\gamma \gg 10 N^2 \ln N$, where $N$ is the number of particles in the target state. Current experiments have $V_0 /\gamma\sim 50$.

[44]  arXiv:1711.08079 (cross-list from q-bio.QM) [pdf, other]
Title: Scalable Inference of Ordinary Differential Equation Models of Biochemical Processes
Comments: To appear in the book "Gene Regulatory Networks: Methods and Protocols"
Subjects: Quantitative Methods (q-bio.QM); Chemical Physics (physics.chem-ph)

Ordinary differential equation models have become a standard tool for the mechanistic description of biochemical processes. If parameters are inferred from experimental data, such mechanistic models can provide accurate predictions about the behavior of latent variables or the process under new experimental conditions. Complementarily, inference of model structure can be used to identify the most plausible model structure from a set of candidates, and thus gain novel biological insight. Several toolboxes can infer model parameters and structure for small- to medium-scale mechanistic models out of the box. However, models for highly multiplexed datasets can require hundreds to thousands of state variables and parameters. For the analysis of such large-scale models, most algorithms require intractably high computation times. This chapter provides an overview of state-of-the-art methods for parameter and model inference, with an emphasis on scalability.

[45]  arXiv:1711.08103 (cross-list from cs.GR) [pdf, other]
Title: Photometric Stereo by UV-Induced Fluorescence to Detect Protrusions on Georgia O'Keeffe's Paintings
Comments: Accepted for publication in the Springer Nature book: Metal Soaps in Art-Conservation & Research
Subjects: Graphics (cs.GR); Applied Physics (physics.app-ph)

A significant number of oil paintings produced by Georgia O'Keeffe (1887-1986) show surface protrusions of varying width, up to several hundreds of microns. These protrusions are similar to those described in the art conservation literature as metallic soaps. Since the presence of these protrusions raises questions about the state of conservation and long-term prospects for deterioration of these artworks, a 3D-imaging technique, photometric stereo using ultraviolet illumination, was developed for the long-term monitoring of the surface-shape of the protrusions and the surrounding paint. Because the UV fluorescence response of painting materials is isotropic, errors typically caused by non-Lambertian (anisotropic) specularities when using visible reflected light can be avoided providing a more accurate estimation of shape. As an added benefit, fluorescence provides additional contrast information contributing to materials characterization. The developed methodology aims to detect, characterize, and quantify the distribution of micro-protrusions and their development over the surface of entire artworks. Combined with a set of analytical in-situ techniques, and computational tools, this approach constitutes a novel methodology to investigate the selective distribution of protrusions in correlation with the composition of painting materials at the macro-scale. While focused on O'Keeffe's paintings as a case study, we expect the proposed approach to have broader significance by providing a non-invasive protocol to the conservation community to probe topological changes for any relatively flat painted surface of an artwork, and more specifically to monitor the dynamic formation of protrusions, in relation to paint composition and modifications of environmental conditions, loans, exhibitions and storage over the long-term.

[46]  arXiv:1711.08143 (cross-list from astro-ph.SR) [pdf]
Title: Iwahashi Zenbei's Sunspot Drawings in 1793 in Japan
Comments: 2017/11/16 accepted for publication in Solar Physics
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); History and Philosophy of Physics (physics.hist-ph)

Three Japanese sunspot drawings associated with Iwahashi Zenbei (1756-1811) are shown here from contemporary manuscripts and woodprint documents with the relevant texts. We revealed the observational date of one of the drawings to be 26 August 1793, and the overall observations lasted for over a year. Moreover, we identified the observational site for the dated drawing at Fushimi in Japan. We then compared his observations with group sunspot number and raw group count from Sunspot Index and Long-term Solar Observations (SILSO) to reveal its data context, and concluded that these drawings filled the gaps in understanding due to the fragmental sunspots observations around 1793. These drawings are important as a clue to evaluate astronomical knowledge of contemporary Japan in the late 19 th century and are valuable as a non-European observation, considering that most sunspot observations up to mid-19 th century are from Europe.

[47]  arXiv:1711.08236 (cross-list from astro-ph.EP) [pdf, other]
Title: Enceladus's crust as a non-uniform thin shell: I Tidal deformations
Authors: Mikael Beuthe
Comments: 71 pages, 12 figures, 5 tables
Journal-ref: Icarus 302 (2018) 145-174
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Geophysics (physics.geo-ph); Space Physics (physics.space-ph)

The geologic activity at Enceladus's south pole remains unexplained, though tidal deformations are probably the ultimate cause. Recent gravity and libration data indicate that Enceladus's icy crust floats on a global ocean, is rather thin, and has a strongly non-uniform thickness. Tidal effects are enhanced by crustal thinning at the south pole, so that realistic models of tidal tectonics and dissipation should take into account the lateral variations of shell structure. I construct here the theory of non-uniform viscoelastic thin shells, allowing for depth-dependent rheology and large lateral variations of shell thickness and rheology. Coupling to tides yields two 2D linear partial differential equations of the 4th order on the sphere which take into account self-gravity, density stratification below the shell, and core viscoelasticity. If the shell is laterally uniform, the solution agrees with analytical formulas for tidal Love numbers; errors on displacements and stresses are less than 5% and 15%, respectively, if the thickness is less than 10% of the radius. If the shell is non-uniform, the tidal thin shell equations are solved as a system of coupled linear equations in a spherical harmonic basis. Compared to finite element models, thin shell predictions are similar for the deformations due to Enceladus's pressurized ocean, but differ for the tides of Ganymede. If Enceladus's shell is conductive with isostatic thickness variations, surface stresses are approximately inversely proportional to the local shell thickness. The radial tide is only moderately enhanced at the south pole. The combination of crustal thinning and convection below the poles can amplify south polar stresses by a factor of 10, but it cannot explain the apparent time lag between the maximum plume brightness and the opening of tiger stripes. In a second paper, I will study tidal dissipation in a non-uniform crust.

[48]  arXiv:1711.08242 (cross-list from cond-mat.soft) [pdf, other]
Title: Filamentous phages as building blocks for reconfigurable and hierarchical self-assembly
Authors: Thomas Gibaud
Journal-ref: Journal of Physics: Condensed Matter 29, 493003 (2017)
Subjects: Soft Condensed Matter (cond-mat.soft); Biological Physics (physics.bio-ph)

Filamentous bacteriophages such as fd-like viruses are monodisperse rod-like colloids that have well defined properties: diameter, length, rigidity, charge and chirality. Engineering those viruses leads to a library of colloidal rods which can be used as building blocks for reconfigurable and hierarchical self-assembly. Their condensation in aqueous solution \th{with additive polymers which act as depletants to induce} attraction between the rods leads to a myriad of fluid-like micronic structures ranging from isotropic/nematic droplets, colloid membranes, achiral membrane seeds, twisted ribbons, $\pi$-wall, pores, colloidal skyrmions, M\"obius anchors, scallop membranes to membrane rafts. Those structures and the way they shape shift not only shed light on the role of entropy, chiral frustration and topology in soft matter but it also mimics many structures encountered in different fields of science. On one hand, filamentous phages being an experimental realization of colloidal hard rods, their condensation mediated by depletion interactions constitutes a blueprint for self-assembly of rod-like particles and provides fundamental foundation for bio- or material oriented applications. On the other hand, the chiral properties of the viruses restrict the generalities of some results but vastly broaden the self-assembly possibilities.

[49]  arXiv:1711.08243 (cross-list from cs.SI) [pdf, ps, other]
Title: Improving local clustering based top-L link prediction methods via asymmetrical link clustering information
Comments: 14 pages, 7 figures
Subjects: Social and Information Networks (cs.SI); Physics and Society (physics.soc-ph)

Networks can represent a wide range of complex systems, such as social, biological and technological systems. Link prediction is one of the most important problems in network analysis, and has attracted much research interest recently. Many link prediction methods have been proposed to solve this problem with various technics. We can note that clustering information plays an important role in solving the link prediction problem. In previous literatures, we find node clustering coefficient appears frequently in many link prediction methods. However, node clustering coefficient is limited to describe the role of a common-neighbor in different local networks, because it can not distinguish different clustering abilities of a node to different node pairs. In this paper, we shift our focus from nodes to links, and propose the concept of asymmetric link clustering (ALC) coefficient. Further, we improve three node clustering based link prediction methods via the concept of ALC. The experimental results demonstrate that ALC-based methods outperform node clustering based methods, especially achieving remarkable improvements on food web, hamster friendship and Internet networks. Besides, comparing with other methods, the performance of ALC-based methods are very stable in both globalized and personalized top-L link prediction tasks.

[50]  arXiv:1711.08252 (cross-list from nlin.CG) [pdf, other]
Title: Effect of self-deflection on a totally asymmetric simple exclusion process with functions of site-assignments
Subjects: Cellular Automata and Lattice Gases (nlin.CG); Statistical Mechanics (cond-mat.stat-mech); Physics and Society (physics.soc-ph)

This study proposes a model of a totally asymmetric simple exclusion process on a single channel lane with functions of site-assignments along the pitlane. The system model attempts to insert a new particle to the leftmost site at a certain probability by randomly selecting one of the empty sites in the pitlane, and reserving it for the particle. Thereafter, the particle is directed to stop at the site only once during its travel. Recently, the system was determined to show a self-deflection effect, in which the site usage distribution biases spontaneously toward the leftmost site, and the throughput becomes maximum when the site usage distribution is slightly biased to the rightmost site, instead of being an exact uniform distribution. Our exact analysis describes this deflection effect and show a good agreement with simulations.

[51]  arXiv:1711.08299 (cross-list from nucl-ex) [pdf, other]
Title: A new scheme to measure the electron-neutrino correlation - the case of $^{6}$He
Authors: I. Mukul (1), M. Hass (1), O. Heber (1), T. Y. Hirsh (2), Y. Mishnayot (1,2,3), M. L. Rappaport (1), G. Ron (3), Y. Shachar (1), S. Vaintraub (2) ((1) Weizmann Institute of Science, (2) Soreq Nuclear Research Center and (3) Hebrew University of Jerusalem)
Comments: 8 pages, 8 figures
Subjects: Nuclear Experiment (nucl-ex); Instrumentation and Detectors (physics.ins-det)

A novel experiment has been commissioned at the Weizmann Institute of Science for the study of weak interactions via a high-precision measurement of the beta-neutrino angular correlation in the radioactive decay of short-lived $^{6}$He. The facility consists of a 14 MeV $d+t$ neutron generator to produce atomic $^{6}$He, followed by ionization and bunching in an electron beam ion source, and injection into an electrostatic ion beam trap. This ion trap has been designed for efficient detection of the decay products from trapped light ions. The storage time in the trap for different stable ions was found to be in the range of 0.6 to 1.2 s at the chamber pressure of $\sim$7$\times$10$^{-10}$ mbar. We present the initial test results of the facility, and also demonstrate an important upgrade of an existing method \cite{stora} for production of light radioactive atoms, viz. $^{6}$He, for the precision measurement. The production rate of $^{6}$He atoms in the present setup has been estimated to be $\sim 1.45\times10^{-4}$ atoms per neutron, and the system efficiency was found to be 4.0$\pm$0.6\%. An improvement to this setup is also presented for the enhanced production and diffusion of radioactive atoms for future use.

[52]  arXiv:1711.08316 (cross-list from cond-mat.stat-mech) [pdf]
Title: Distribution of size particles in the Gibbs system
Authors: V. V. Ryazanov
Comments: 16 pages, in Russian, 2 figures
Subjects: Statistical Mechanics (cond-mat.stat-mech); Chemical Physics (physics.chem-ph)

In the framework of the Gibbs statistical theory, the question of the size of the particles forming the statistical system is investigated. This task is relevant for a wide variety of applications. The distribution for particle sizes and the moments of this quantity are determined from probabilistic considerations. The results are compared with different models and approximations. The particle size depends on the interactions in the system, on the compressibility factor, on the number of interacting particles. The cases of the absence and presence of a rigid incompressible particle core are considered.

[53]  arXiv:1711.08385 (cross-list from cond-mat.soft) [pdf, other]
Title: Mesoscopic Modelling and Simulation of Soft Matter
Comments: 16 pages, 6 figures
Journal-ref: Soft Matter, 2017
Subjects: Soft Condensed Matter (cond-mat.soft); Computational Physics (physics.comp-ph)

The deformability of soft condensed matter often requires modelling of hydrodynamical aspects to gain quantitative understanding. This, however, requires specialised methods that can resolve the multiscale nature of soft matter systems. We review a number of the most popular simulation methods that have emerged, such as Langevin dynamics, dissipative particle dynamics, multi-particle collision dynamics, sometimes also referred to as stochastic rotation dynamics, and the lattice-Boltzmann method. We conclude this review with a short glance at current compute architectures for high-performance computing and community codes for soft matter simulation.

[54]  arXiv:1711.08428 (cross-list from cond-mat.stat-mech) [pdf, other]
Title: Computing return times or return periods with rare event algorithms
Subjects: Statistical Mechanics (cond-mat.stat-mech); Computational Physics (physics.comp-ph); Data Analysis, Statistics and Probability (physics.data-an)

The average time between two occurrences of the same event, referred to as its return time (or return period), is a useful statistical concept for practical applications. For instance insurances or public agency may be interested by the return time of a 10m flood of the Seine river in Paris. However, due to their scarcity, reliably estimating return times for rare events is very difficult using either observational data or direct numerical simulations. For rare events, an estimator for return times can be built from the extrema of the observable on trajectory blocks. Here, we show that this estimator can be improved to remain accurate for return times of the order of the block size. More importantly, we show that this approach can be generalised to estimate return times from numerical algorithms specifically designed to sample rare events. So far those algorithms often compute probabilities, rather than return times. The approach we propose provides a computationally extremely efficient way to estimate numerically the return times of rare events for a dynamical system, gaining several orders of magnitude of computational costs. We illustrate the method on two kinds of observables, instantaneous and time-averaged, using two different rare event algorithms, for a simple stochastic process, the Ornstein-Uhlenbeck process. As an example of realistic applications to complex systems, we finally discuss extreme values of the drag on an object in a turbulent flow.

[55]  arXiv:1711.08448 (cross-list from cs.SI) [pdf, other]
Title: Node and layer eigenvector centralities for multiplex networks
Subjects: Social and Information Networks (cs.SI); Numerical Analysis (math.NA); Physics and Society (physics.soc-ph)

Eigenvector-based centrality measures are among the most popular centrality measures in network science. The underlying idea is intuitive and the mathematical description is extremely simple in the framework of standard, mono-layer networks. Moreover, several efficient computational tools are available for their computation. Moving up in dimensionality, several efforts have been made in the past to describe an eigenvector-based centrality measure that generalizes Bonacich index to the case of multiplex networks. In this work, we propose a new definition of eigenvector centrality that relies on the Perron eigenvector of a multi-homogeneous map defined in terms of the tensor describing the network. We prove that existence and uniqueness of such centrality are guaranteed under very mild assumptions on the multiplex network. Extensive numerical studies are proposed to test the newly introduced centrality measure and to compare it to other existing eigenvector-based centralities.

Replacements for Thu, 23 Nov 17

[56]  arXiv:1207.0437 (replaced) [pdf, other]
Title: Dendrogram/Regionalization of U. S. Counties Based upon Migration Flows
Authors: Paul B. Slater
Comments: 44 pages, certain passages extracted from arXiv:0809.2768, technical problem addressed in more faithfully including the multi-page dendrogram (by slightly scaling the individual pages), URL link corrected
Subjects: Physics and Society (physics.soc-ph); Social and Information Networks (cs.SI); Applications (stat.AP)
[57]  arXiv:1211.1936 (replaced) [pdf, ps, other]
Title: Invariance of the fine structure constant with temperature of the expanding universe
Comments: 7 pages, 1 figure
Journal-ref: Canadian Journal of Physics 93, 1551 (2015)
Subjects: General Physics (physics.gen-ph)
[58]  arXiv:1503.05878 (replaced) [pdf, ps, other]
Title: Inhomogeneous cosmology in the cosmic rest frame revisited
Authors: Günter Scharf
Comments: 21 pages, no figure
Subjects: General Physics (physics.gen-ph); General Relativity and Quantum Cosmology (gr-qc)
[59]  arXiv:1612.04532 (replaced) [pdf, ps, other]
Title: Influence of cell-cell interactions on the population growth rate in a tumor
Authors: Yong Chen
Comments: 5 pages, 2 figures
Journal-ref: Commun. Theor. Phys. 68, 798 (2017)
Subjects: Populations and Evolution (q-bio.PE); Biological Physics (physics.bio-ph); Tissues and Organs (q-bio.TO)
[60]  arXiv:1702.06903 (replaced) [pdf, other]
Title: Finding multiple core-periphery pairs in networks
Comments: 11 figures and 9 tables. MATLAB codes are available at www.naokimasuda.net/cp_codes.zip
Journal-ref: Phys. Rev. E 96, 052313 (2017)
Subjects: Physics and Society (physics.soc-ph); Social and Information Networks (cs.SI)
[61]  arXiv:1705.05982 (replaced) [pdf, ps, other]
Title: Understanding Quality Factor Degradation in Superconducting Niobium Cavities at Low Microwave Field Amplitudes
Comments: final version
Subjects: Accelerator Physics (physics.acc-ph); Superconductivity (cond-mat.supr-con); Quantum Physics (quant-ph)
[62]  arXiv:1705.11067 (replaced) [pdf, ps, other]
Title: On Maxwell-like equations for Gravitational Field
Authors: Gustavo V. Lopez
Comments: 14 pages, non figures
Subjects: General Physics (physics.gen-ph)
[63]  arXiv:1706.02371 (replaced) [pdf, other]
Title: From two-dimensional to three-dimensional turbulence through two-dimensional three-component flows
Comments: postprint version
Journal-ref: Phys. Fluids 29, 111101 (2017)
Subjects: Fluid Dynamics (physics.flu-dyn)
[64]  arXiv:1706.09881 (replaced) [pdf, other]
Title: Measurement of radio-frequency temporal phase modulation using spectral interferometry
Comments: final version, 5 pages, 4 figures
Journal-ref: J. Mod. Opt. 65, 262--267 (2018)
Subjects: Instrumentation and Detectors (physics.ins-det); Optics (physics.optics)
[65]  arXiv:1707.03765 (replaced) [pdf, other]
Title: Computing Singularly Perturbed Differential Equations
Comments: This paper has appeared in Journal of Computational Physics, Volume 354 (pages 417-446)
Journal-ref: Journal of Computational Physics 354 (2018) 417-446
Subjects: Numerical Analysis (math.NA); Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph)
[66]  arXiv:1707.05194 (replaced) [pdf, other]
Title: A new model with Serpent for the first criticality benchmarks of the TRIGA Mark II reactor
Journal-ref: Annals of Nuclear Energy 113 (2018) 171-176
Subjects: Instrumentation and Detectors (physics.ins-det); Applied Physics (physics.app-ph)
[67]  arXiv:1707.07859 (replaced) [pdf, other]
Title: Wigner Function Reconstruction in Levitated Optomechanics
Comments: 9 pages, 3 figures
Journal-ref: Quantum Measurements and Quantum Metrology, 4(1), pp. 17-25 (2017)
Subjects: Quantum Physics (quant-ph); Optics (physics.optics)
[68]  arXiv:1707.08116 (replaced) [pdf, other]
Title: Accelerate to see more: light emission by accelerated dynamic anapoles
Authors: V. Savinov
Comments: Change from previous version. The radiation pattern in Fig. 1 has been corrected
Subjects: Classical Physics (physics.class-ph)
[69]  arXiv:1707.09803 (replaced) [pdf, ps, other]
Title: Latitudinal trends in human primary activities: characterizing the winter day as a synchronizer
Comments: Changes: Descriptive statistics and bivariate correlations added. Introduction, Results and Discussion largely modified. RevTeX4-1 27 pages, 6 figures, 13 tables. Data from Time Use Surveys, Hetus and Eurostat
Subjects: Physics and Society (physics.soc-ph)
[70]  arXiv:1708.01653 (replaced) [pdf, other]
Title: Strong-pinning regimes by spherical inclusions in anisotropic type-II superconductors
Comments: 24 pages, 16 figures
Subjects: Superconductivity (cond-mat.supr-con); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph); Computational Physics (physics.comp-ph)
[71]  arXiv:1708.07869 (replaced) [pdf]
Title: A New Amplification Regime for Traveling Wave Tubes with Third Order Modal Degeneracy
Comments: 15 pages, 11 figures
Subjects: Applied Physics (physics.app-ph); Plasma Physics (physics.plasm-ph)
[72]  arXiv:1710.03056 (replaced) [pdf, ps, other]
Title: On the resolution of a MIEZE spectrometer
Authors: N. Martin
Comments: 19 pages, 6 figures
Journal-ref: Nuclear Inst. and Methods in Physics Research, A 882 (2018) 11-16
Subjects: Instrumentation and Detectors (physics.ins-det)
[73]  arXiv:1710.10140 (replaced) [pdf, other]
Title: Efficient manifold tracing for planar maps
Subjects: Chaotic Dynamics (nlin.CD); Plasma Physics (physics.plasm-ph)
[74]  arXiv:1710.11184 (replaced) [pdf, other]
Title: Correlations and Clustering in Wholesale Electricity Markets
Comments: 30 pages, several pictures
Subjects: Statistical Finance (q-fin.ST); Physics and Society (physics.soc-ph)
[75]  arXiv:1710.11356 (replaced) [pdf, ps, other]
Title: Collimated Ultra-Bright Gamma-Rays from a PW-Laser-Driven Wire Wiggler
Comments: 6 pages, 4 figures
Subjects: Plasma Physics (physics.plasm-ph)
[76]  arXiv:1711.00732 (replaced) [pdf, ps, other]
Title: Experimental and theoretical comparison of the cooling performance between standard and double-bright EIT cooling
Comments: 15 pages, 13 figures. Minor changes in the text, new title, and supplementary material moved to the appendix. Results unchanged from first version
Subjects: Quantum Physics (quant-ph); Atomic Physics (physics.atom-ph)
[77]  arXiv:1711.01833 (replaced) [pdf, ps, other]
Title: Jet activity in the central BH of the Milky Way in 4th and 14th centuries CE
Authors: Olga I. Piskounova (1), Irina V. Tamarkina (2,3) ((1) Lebedev Physics Institute, Moscow, Russia, (2) Wisconsin-Madison Uni., USA, (3) Hebrew Uni., Jerusalem)
Comments: 10 pages, 10 figures
Subjects: History and Philosophy of Physics (physics.hist-ph); Astrophysics of Galaxies (astro-ph.GA)
[78]  arXiv:1711.02874 (replaced) [pdf, ps, other]
Title: Excited states of two-dimensional solitons supported by the spin-orbit coupling and field-induced dipole-dipole repulsion
Comments: 8 pages, 3 figures, and 73 references
Subjects: Quantum Gases (cond-mat.quant-gas); Pattern Formation and Solitons (nlin.PS); Optics (physics.optics)
[79]  arXiv:1711.06339 (replaced) [pdf, other]
Title: Instantons and Fluctuations in a Lagrangian Model of Turbulence
Comments: 28 pages, 9 figures
Subjects: Fluid Dynamics (physics.flu-dyn)
[80]  arXiv:1711.06676 (replaced) [pdf, ps, other]
Title: Sidebands suppression of 852 nm Cesium Faraday anomalous dispersion optical filter by argon gas
Subjects: Atomic Physics (physics.atom-ph); Quantum Physics (quant-ph)
[81]  arXiv:1711.07305 (replaced) [pdf, other]
Title: Ultraslow long-living plasmons with electromagnetically induced transparency
Comments: 5 pages, 5 figures
Subjects: Optics (physics.optics)
[82]  arXiv:1711.07470 (replaced) [pdf, other]
Title: Theory and Practice of Electron Diffraction from Single Atoms and Extended Objects using an Electron Microscope Pixel Array Detector
Comments: 16 pages, 9 figures
Subjects: Instrumentation and Detectors (physics.ins-det)
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