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Physics

New submissions

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New submissions for Fri, 22 Jun 18

[1]  arXiv:1806.07886 [pdf, other]
Title: Evaluation of noise limits of a precision ADC for direct digital signal integration of magnetic measurements
Subjects: Instrumentation and Detectors (physics.ins-det); Nuclear Experiment (nucl-ex)

The characterization of laboratory plasma instabilities, magnetic reconnection and turbulence associated phenomena, require the simultaneous signal sampling from arrays of magnetic sensors (hundreds or even thousands) to obtain spatial resolution, with several hundred kHz for time resolution. Magnetic measurements based on pick-up (Mirnov) coil are quite common in experimental pulsed devices for plasma research, thanks to their simplicity and reliability. Being the signal from this type of sensor proportional to the time variation of the magnetic field ($dB/dt$), it has to be time-integrated to recover the instant value of magnetic field. Depending on the required integration time usually either analog integrators or chopped integrators are used. However these solutions tend to limit the frequency bandwidth in the kHz range, they are not easy to design and build, and require additional fast channels to directly acquire the $dB/dt$ signal to recover the plasma dynamic features at higher frequencies. In this paper we evaluate the feasibility of using a direct single channel precision ADC to allow the simultaneous acquisition of $dB/dt$ measurements and to provide the integrated B measurement by means of digital integration on the new RFX-mod2 device. On this purpose we interfaced an existing ADC-module to a Xilinx Zynq FPGA, in order to evaluate the intrinsic noise and to investigate the feasible integration window of this configuration. The result opens the door to a compact, cost-effective and reliable acquisition system, usable for simultaneous real-time control and transient signal recording, scalable from tenths to thousands channels, applicable to a broad class of pulsed plasma experimental devices.

[2]  arXiv:1806.07911 [pdf, other]
Title: Self-organization and Nonuniversal Anomalous Scaling in Non-Newtonian Turbulence
Comments: 5 pages, 4 figures
Subjects: Fluid Dynamics (physics.flu-dyn)

We investigate through Direct Numerical Simulations (DNS) the statistical properties of turbulent flows in the inertial subrange for non-Newtonian power-law fluids. The structural invariance found for the vortex size distribution is achieved through a self-organized mechanism at the microscopic scale of the turbulent motion that adjusts, according to the rheological properties of the fluid, the ratio between the viscous dissipations inside and outside the vortices. Moreover, the deviations from the K41 theory of the structure functions' exponents reveal that the anomalous scaling exhibits a systematic nonuniversal behavior with respect to the rheological properties of the fluids.

[3]  arXiv:1806.07920 [pdf, other]
Title: Tunable Rydberg excitons maser
Comments: 4 pages, 5 figures
Subjects: Applied Physics (physics.app-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

We propose a solid state maser based on Cu2O, where ensemble of highly excited Rydberg exciton states serves as a gain medium. We show that the system is highly tunable with external electric field, allowing for a wide range of emission frequencies. Numerical simulations of system dynamics are performed to optimize the conditions for efficient masing and estimate the emission power.

[4]  arXiv:1806.07940 [pdf]
Title: Improved Magnetron Stability And Reduced Noise In Efficient Transmitters For Superconducting Accelerators
Authors: G. Kazakevich, R. Johnson (MUONS Inc., Batavia) V. Lebedev, V. Yakovlev (Fermilab)
Comments: 3 pp
Subjects: Accelerator Physics (physics.acc-ph)

State of the art high-current superconducting accelerators require efficient RF sources with a fast dynamic phase and power control. This allows for compensation of the phase and amplitude deviations of the accelerating voltage in the Superconducting RF (SRF) cavities caused by microphonics, etc. Efficient magnetron transmitters with fast phase and power control are attractive RF sources for this application. They are more cost effective than traditional RF sources such as klystrons, IOTs and solid-state amplifiers used with large scale accelerator projects. However, unlike traditional RF sources, controlled magnetrons operate as forced oscillators. Study of the impact of the controlling signal on magnetron stability, noise and efficiency is therefore important. This paper discusses experiments with 2.45 GHz, 1 kW tubes and verifies our analytical model which is based on the charge drift approximation.

[5]  arXiv:1806.07965 [pdf, ps, other]
Title: Nonparaxial electromagnetic Bragg scattering in periodic media with PT symmetry
Subjects: Optics (physics.optics)

The evolution of a pair of resonant Bragg modes through a medium characterized by a complex one-dimensional $\mathcal{PT}$-symmetric periodic permittivity is thoroughly investigated. Analytic solutions of Maxwell's equations are derived beyond the paraxial approximation to investigate the periodic energy exchange that occurs between the Bragg modes for the Hermitian lattices as well as for complex lattices. Three regimes defined by the symmetry breaking point are discussed: below it, above it and at it. These regimes are determined by the existence of four real eigenvalues in the symmetric phase, which collide and coalesce into a pair at the breaking point. Above the critical value each member of the pair bifurcates into a pair of complex values. Therefore, the complex lattice reveals a variety of wave dynamics depending on the gain/loss balance. In all regimes of the transition the signature of $\mathcal{PT}$-symmetric systems is present, as the evolution is always nonreciprocal and unidirectional.

[6]  arXiv:1806.07972 [pdf]
Title: Proposal and demonstration of lock-in pixels for indirect time-of-flight measurements based on germanium-on-silicon technology
Subjects: Instrumentation and Detectors (physics.ins-det)

We propose the use of germanium-on-silicon technology for indirect time-of-flight depth sensing as well as three-dimensional imaging applications, and demonstrate a novel pixel featuring a high quantum efficiency and a large frequency bandwidth. Compared to conventional silicon pixels, our germanium-on-silicon pixels simultaneously maintain a high quantum efficiency and a high demodulation contrast deep into GHz frequency regime, which enable consistently superior depth accuracy in both indoor and outdoor scenarios. Device simulation, system performance comparison, and electrical/optical characterization of the fabricated pixels are presented. Our work paves a new path to high-performance time-of-flight sensors and imagers, as well as potential adoptions of eye-safe lasers (wavelengths > 1.4 {\mu}m) that fall outside of the operation window of conventional silicon pixels.

[7]  arXiv:1806.07975 [pdf, other]
Title: Relativistic coupling of phase and amplitude noise in optical interferometry
Subjects: Instrumentation and Detectors (physics.ins-det); Optics (physics.optics)

Extraneous motion of optical elements in an interferometer lead to excess noise. Typically, fluctuations in the effective path length lead to phase noise, while beam-pointing leads to apparent amplitude noise. For a transmissive optic moving along the optical axis, neither effect should exist. However, relativity of motion suggests that even in this case, small corrections of order $v/c$ ($v$ the velocity of the optic), give rise to phase and amplitude noise on the light. Here we calculate the effect of this relativistic mechanism of noise coupling, and discuss when such an effect would limit the sensitivity of optical interferometers.

[8]  arXiv:1806.07993 [pdf, other]
Title: Asymmetric concentration dependence of segregation fluxes in granular flows
Subjects: Fluid Dynamics (physics.flu-dyn)

We characterize the local concentration dependence of segregation velocity and segregation flux in both size and density bidisperse gravity-driven free-surface granular flows as a function of the particle size ratio and density ratio, respectively, using discrete element method (DEM) simulations. For a range of particle size ratios and inlet volume flow rates in size-bidisperse flows, the maximum segregation flux occurs at a small particle concentration less than 0.5, which decreases with increasing particle size ratio. The segregation flux increases up to a size ratio of 2.4 but plateaus from there to a size ratio of 3. In density bidisperse flows, the segregation flux is greatest at a heavy particle concentration less than 0.5 which decreases with increasing particle density ratio. The segregation flux increases with increasing density ratio for the extent of density ratios studied, up to 10. We further demonstrate that the simulation results for size driven segregation are in accord with the predictions of the kinetic sieving segregation model of Savage and Lun.

[9]  arXiv:1806.07997 [pdf, other]
Title: First-Principles Threshold Calculation of Photonic Crystal Surface-Emitting Lasers Using Rigorous Coupled Wave Analysis
Comments: 13 pages, 4 figures
Subjects: Optics (physics.optics)

We show that the threshold of a photonic crystal surface-emitting laser can be calculated from first-principles by the method of rigorous coupled wave analysis (RCWA), which has been widely used to simulate the response spectra of passive periodic structures. Here, the scattering matrix (S-matrix) of a surface-emitting laser structure with added gain is calculated on the complex frequency plane using RCWA, and the lasing threshold is determined by the value of gain for which the pole of the S-matrix reaches the real axis. This approach can be used for surface emitting laser struc tures in general, and is particularly useful for the surface emitting laser systems with complex in-plane structures.

[10]  arXiv:1806.07998 [pdf, other]
Title: Evidence of inverse cascades in the cerebral dynamics: Spontaneous symmetry breaking during arterial inflow
Subjects: Biological Physics (physics.bio-ph); Medical Physics (physics.med-ph); Neurons and Cognition (q-bio.NC)

Cerebral fluid dynamics require a reverse energy mechanism to transport water and metabolites from tissue into veins. Recent findings in active flow of bacteria have shown that such a mechanism involving backward energy cascades, so-called inverse cascades may exist only during spontaneously broken mirror-symmetries. Here, we wanted to investigate whether and, if so when symmetries break during a heart cycle. We used multiple spin echos (MSE)s in magnetic resonance imaging (MRI) which can detect broken spherical symmetries. We found MSEs in brain tissue which appeared during arterial pulsation in a highly synchronized fashion in most parts of the brain. The timing suggests that the reverse energy flow is initiated during the energy injection of the heartbeat and ends with the isovolumetric vessel contraction. This interleaved process may explain how the illusive pulse wave traveling through the brain emerges as well as underlying principles of cerebral autoregulation and neurovascular coupling.

[11]  arXiv:1806.08001 [pdf, other]
Title: Analog control with two Artificial Axons
Comments: 8 pages, 11 figures
Subjects: Biological Physics (physics.bio-ph); Neurons and Cognition (q-bio.NC)

The artificial axon is a recently introduced synthetic assembly of supported lipid bilayers and voltage gated ion channels, displaying the basic electrophysiology of nerve cells. Here we demonstrate the use of two artificial axons as control elements to achieve a simple task. Namely, we steer a remote control car towards a light source, using the sensory input dependent firing rate of the axons as the control signal for turning left or right. We present the result in the form of the analysis of a movie of the car approaching the light source. In general terms, with this work we pursue a constructivist approach to exploring the nexus between machine language at the nerve cell level and behavior.

[12]  arXiv:1806.08008 [pdf, other]
Title: Optimized nonlinear terahertz response of graphene in a parallel-plate waveguide
Subjects: Applied Physics (physics.app-ph)

Third harmonic generation of terahertz radiation is expected to occur in monolayer graphene due to the nonlinear relationship between the crystal momentum and the current density. In this work, we calculate the terahertz nonlinear response of graphene inside a parallel-plate waveguide including pump depletion, self-phase, and cross-phase modulation. To overcome the phase mismatching between the pump field and third-harmonic field at high input fields due to self-phase and cross-phase modulation, we design a waveguide with two dielectric layers with different indices of refraction. We find that, by tuning the relative thicknesses of the two layers, we are able to improve phase matching, and thereby increase the power efficiency of the system by more than a factor of two at high powers. With this approach, we find that dispite the loss in this system, for an incident frequency of $2$ THz, we are able to achieve power efficiencies of $75 \%$ for graphene with low Fermi energies of $20$ meV and up to $35\%$ when the Fermi energy is $100$ meV.

[13]  arXiv:1806.08019 [pdf, other]
Title: Laterally confined photonic crystal surface emitting laser based on monolayer tungsten disulfide operating at room temperature
Comments: 10 pages, 4 figures
Subjects: Optics (physics.optics)

We report a photonic crystal surface emitting laser using monolayer tungsten disulfide as the gain medium. The cavity design utilizes a heterostructure in the photonic crystal lattice to provide lateral confinement for a high quality factor with a compact active region. Room temperature continuous wave lasing is realized after integrating monolayer tungsten disulfide flakes onto the silicon nitride photonic crystal on quartz substrate. Highly directional, near surface normal emission has also been experimentally demonstrated.

[14]  arXiv:1806.08022 [pdf, other]
Title: A space-time smooth artificial viscosity method with wavelet noise indicator and shock collision scheme, Part 2: the 2-D case
Comments: 42 pages, 21 figures
Subjects: Computational Physics (physics.comp-ph); Numerical Analysis (math.NA)

This is the second part to our companion paper [13]. Herein, we generalize to two space dimensions the C-method developed in [14,13] for adding localized, space-time smooth artificial viscosity to nonlinear systems of conservation laws that propagate shock waves, rarefaction waves, and contact discontinuities. For gas dynamics, the C-method couples the Euler equations to scalar reaction-diffusion equations, which we call C-equations, whose solutions serve as space-time smooth artificial viscosity indicators for shocks and contacts.
We develop a high-order numerical algorithm for gas dynamics in 2-D which can accurately simulate the Rayleigh-Taylor (RT) instability with Kelvin-Helmholtz (KH) roll-up of the contact discontinuity, as well as shock collision and bounce-back. Solutions to our C-equations not only indicate the location of the shocks and contacts, but also track the geometry of the evolving fronts. This allows us to implement both directionally isotropic and anisotropic artificial viscosity schemes, the latter adding diffusion only in directions tangential to the evolving front.
We additionally produce a novel shock collision indicator function, which naturally activates during shock collision, and then smoothly deactivates. Moreover, we implement a high-frequency 2-D wavelet-based noise detector together with an efficient and localized noise removal algorithm.
To test the methodology, we use a highly simplified WENO-based discretization scheme, devoid of any approximate Riemann solvers. We provide numerical results for some classical 2-D test problems, including the RT problem, the Noh problem, a circular explosion problem from the Liska and Wendroff [9] review paper, and a shock-wall collision problem.

[15]  arXiv:1806.08023 [pdf, ps, other]
Title: A space-time smooth artificial viscosity method with wavelet noise indicator and shock collision scheme, Part 1: the 1-D case
Comments: 42 pages, 20 figures
Subjects: Computational Physics (physics.comp-ph); Numerical Analysis (math.NA)

In this first part of two papers, we extend the C-method developed in [30] for adding localized, space-time smooth artificial viscosity to nonlinear systems of conservation laws that propagate shock waves, rarefaction waves, and contact discontinuities in one space dimension. For gas dynamics, the C-method couples the Euler equations to a scalar reaction-diffusion equation, whose solution C serves as a space-time smooth artificial viscosity indicator.
The purpose of this paper is the development of a high-order numerical algorithm for shock-wall collision and bounce-back. Specifically, we generalize the original C-method by adding a new collision indicator, which naturally activates during shock-wall collision. Additionally, we implement a new high-frequency wavelet-based noise detector together with an efficient and localized noise removal algorithm. To test the methodology, we use a highly simplified WENO-based discretization scheme, devoid of any approximate Riemann solvers. We show that our scheme improves the order of accuracy of our WENO algorithm, handles extremely strong discontinuities (ranging up to ten orders of magnitude), allows for shock collision and bounce back, and removes high frequency noise. The well-known "wall heating" phenomenon is also explained. This method is generalized to two space dimensions in the second part of this work [31].

[16]  arXiv:1806.08025 [pdf]
Title: An Ultra-high-Speed Waveform Digitizer Prototype Based on Gigabit Ethernet for Plasma Diagnostics
Comments: 3 pages,6 figures,21st IEEE Real Time Conference
Subjects: Instrumentation and Detectors (physics.ins-det)

An ultra-high-speed waveform digitizer prototype based on gigabit Ethernet has been developed. The prototype is designed to read out signals of detectors to realize the accurate measurement of various physical quantities for plasma diagnostics. The prototype includes an ultra-high-speed analog-to-digital converter (ADC) used to realize high speed digitization, a Xilinx Kintex-7 field-programmable gate array (FPGA) used for system configuration and digital signal processing, a DDR3 memory bar for data storage, and a gigabit Ethernet transceiver for interfacing with a computer. The sampling rate of the prototype is up to 5Gsps with 10-b resolution. The features of the prototype are described in detail.

[17]  arXiv:1806.08042 [pdf]
Title: Science Education in the 21st Century
Authors: Sun Kwok
Subjects: Physics Education (physics.ed-ph)

The traditional university science curriculum was designed to train specialists in specific disciplines. However, in universities all over the world, science students are going into increasingly diverse careers and the current model does not fit their needs. Advances in technology also make certain modes of learning obsolete. In the last 10 years, the Faculty of Science of the University of Hong Kong has undertaken major curriculum reforms. A sequence of science foundation courses required of all incoming science students are designed to teach science in an integrated manner, and to emphasize the concepts and utilities, not computational techniques, of mathematics. A number of non-discipline specific common core courses have been developed to broaden students' awareness of the relevance of science to society and the interdisciplinary nature of science. By putting the emphasis on the scientific process rather than the outcome, students are taught how to identify, formulate, and solve diverse problems.

[18]  arXiv:1806.08046 [pdf, other]
Title: Design and Evaluation of LAr Trigger Digitizer Board in the ATLAS Phase-I Upgrade
Comments: This manuscript for conference record of the 21st IEEE Real Time conference only
Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)

The LHC upgrade is planned to enhance the instantaneous luminosity during Run 3 from 2021 through 2023. The Phase-I upgrade of the trigger readout electronics for the ATLAS Liquid Argon (LAr) Calorimeters will be installed during the second long shutdown of LHC in 2019-2020. In this upgrade, the so-called super cells are introduced to provide higher granularity, higher resolution and longitudinal shower shape information from the LAr calorimeters to the level-1 trigger processors. A new LAr Trigger Digitizer Board (LTDB) will process and digitize 320 channels of super cell signals, and transmit them via 40 fiber optical links to the back end where data are further processed and transmitted to the trigger processors. Five pairs of bidirectional GBT links are used for slow control from the Front-end LInks eXchange (FELIX) in the ATLAS TDAQ system. LTDB also outputs 64 summed analog signals to the current Tower Builder Board via the new baseplane. A test system is developed to evaluate all functions of the LTDB and carry out the performance measurement. A back end PCIe card is designed which has the circuit to interface to the ATLAS trigger, time and control system. It controls the generation of injection signals to the LTDB for performance test. It also configures and calibrates all ASICs on the LTDB. A front-end test board, test baseplane and a crate are designed to extend the capability of the test setup, which will be used for the production test of the 124 LTDB boards.

[19]  arXiv:1806.08066 [pdf, other]
Title: Dimensionality-dependent crossover in motility of polyvalent burnt-bridges ratchets
Comments: Includes SI, but not supporting movies
Subjects: Biological Physics (physics.bio-ph); Statistical Mechanics (cond-mat.stat-mech); Subcellular Processes (q-bio.SC)

The burnt-bridges ratchet (BBR) mechanism is a model for biased molecular motion whereby the construct destroys track binding sites as it progresses, and therefore acts as a diffusing forager, seeking new substrate sites. Using Monte Carlo simulations that implement the Gillespie algorithm, we investigate the kinetic characteristics of simple polyvalent BBRs as they move on tracks of increasing width. We find that as the track width is increased the BBRs remain nearly ballistic for considerable track widths proportional to the span (leg length) of the polyvalent walker, before transitioning to near-conventional diffusion on two-dimensional tracks. We find there exists a tradeoff in BBR track association time and superdiffusivity in the BBR design parameter space of span, polyvalency and track width. Furthermore, we develop an analytical model to describe the ensembleaverage motion on the track and find it is in good agreement with our Gillespie simulation results. This work offers insights into design criteria for de novo BBRs and their associated tracks, where experimentalists seek to optimize directionality and track association time.

[20]  arXiv:1806.08068 [pdf, ps, other]
Title: A simple and efficient numerical procedure to compute the inverse Langevin function with high accuracy
Subjects: Computational Physics (physics.comp-ph); Soft Condensed Matter (cond-mat.soft)

The inverse Langevin function is a fundamental part of the statistical chain models used to describe the behavior of polymeric-like materials, appearing also in other fields such as magnetism, molecular dynamics and even biomechanics. In the last four years, several approximants of the inverse Lanvegin function have been proposed. In most of them, optimization techniques are used to reduce the relative error of previously published approximants to reach orders of magnitude of order 1E-3% to 1E-2% In this paper a new simple and efficient numerical approach to calculate the inverse Langevin function is proposed. Its main feature is the drastic reduction of the maximum relative error in all the domain [0,1), halving also the function evaluation times. Specifically, in [0,0.96], the order of magnitude of the maximum relative error is order 1E-9%, which corresponds with a maximum absolute error of order 1E-14, whereas within [0.91,1) the relative error is of order 1E-7%. The method consists in the discretization of the Langevin function, the calculation of the inverse of these discretization points and their interpolation by cubic splines. In order to reproduce the asymptotic behavior of the inverse Langevin function, a [2/1] rational function is considered only in the asymptotic zone and with the same C2 continuity requirements as cubic splines. The use of these C2 piecewise cubic polynomials ensures the continuity of the function up to the second derivative and its integration in any interval.

[21]  arXiv:1806.08070 [pdf]
Title: Data Acquisition System for CSNS Neutron Beam Monitor
Comments: 21st IEEE Real Time Conference
Subjects: Instrumentation and Detectors (physics.ins-det)

In Chinese Spallation Neutron Source (CSNS), proton beam is used to hit metal tungsten target, and then high flux neutrons are generated for experiments on instruments. For neutron flux spectrum correction, boron-coated GEM, lithium glass and 3He are used as neutron beam monitor in instruments. To be integrated into neutron instrument control, a new DAQ software for neutron beam monitor is developed, called NEROS (Neutron Event Readout System). NEROS is based on EPICS V4 and a unified data format for CSNS neutron beam monitor is defined. The framework and software design of NEROS is introduced in this paper, including real-time data readout, data processing, data visualization and data storage in Nexus format. The performance is evaluated through offline test, X-ray test and 252Cf test. The deployment of NEROS and its running result in CSNS instrument commissioning are also introduced in this paper.

[22]  arXiv:1806.08076 [pdf]
Title: The Proton Beam Real-time Monitor System in CSNS
Comments: 21st IEEE Real Time Conference
Subjects: Instrumentation and Detectors (physics.ins-det)

In Chinese Spallation Neutron Source (CSNS), proton beam is used to hit metal tungsten target, and then high flux neutron are generated for experiments on instruments. For neutron flux spectrum correction, the current of proton beam is for each instrument.
A real time monitor system is developed in CSNS, to monitor, broadcast and record each pulse of proton. Each proton pulse charge is measured and marked with high-precision timestamp. Then, the result of measurement will be broadcasted to control room and each neutron instrument. In control room, the proton charge of each pulse is listened and stored in database by agent program for offline use. The high-precision timestamp can be used to proton charge and neutron data alignment in time scale. The architecture of proton beam monitor system is introduced in this paper. And the performance of this system is evaluated in this paper.

[23]  arXiv:1806.08094 [pdf, ps, other]
Title: Higher-component quadrupole polarizabilities: Estimations for the clock states of the alkaline earth-metal ions
Comments: Accepted for publication in Phys. Rev. A
Subjects: Atomic Physics (physics.atom-ph)

Derivations for the higher tensor components of the quadrupole polarizabilities are given and their values for the metastable states of the Ca$^+$, Sr$^+$ and Ba$^+$ alkaline earth-metal ions are estimated. We also give the scalar quadrupole polarizabilities of the ground and metastable states of these ions to compare our results with the previously available theoretical and experimental results. Reasonably good agreement between our calculations with the previous values of scalar quadrupole polarizabilities demonstrate their correctness. The reported scalar and tensor quadrupole polarizabilities could be very useful to estimate the uncertainties due to the gradient of the electric fields in the clock frequencies of the above alkaline earth-metal ions when accuracies of these frequency measurements attain below 10$^{-19}$ precision level.

[24]  arXiv:1806.08113 [pdf]
Title: Electrohydrodynamic interaction between droplet pairs in confined shear flow
Comments: 22 pages, 10 figures
Subjects: Fluid Dynamics (physics.flu-dyn)

The present study deals with the numerical as well as asymptotic analysis of the electrohydrodynamic interaction between two deformable droplets in a confined shear flow. Considering both the phases as leaky dielectric, we have performed numerical simulations to study the effect of channel confinement on the drop trajectories in the presence of a uniform electric field. Two important varieties of motion are identified in the present analysis, namely (i) the reversing motion and (ii) the passing over motion. The study suggests that conversion of the passing over motion to the reversing motion or vice versa is possible via modulating the strength of the imposed electric field. Such a conversion of the pattern of droplet migration is also possible in a confined domain due to change in different electrical properties of the system. The present numerical model is also able to predict the pattern of the trajectory of individual droplets depending on the initial distance separating the two. For example, a smaller initial distance results in a reversing motion whereas a passing over motion is predicted when the distance between the droplets is significantly large. However, the final positions of the droplets are found to be independent of their initial positions. Interestingly, presence of electric field is found to prevent droplet coalescence to a certain extent depending on its strength, thus rendering the emulsion stable. A small deformation asymptotic model is also developed under the assumption of negligible fluid inertia to support the numerical results for the limiting case of an unbounded flow. The current investigation successfully presents a novel technique to predict the precise positions of a system of droplets in a micro-channel and how electric field can be used as a tool to modulate droplet trajectories in an emulsion.

[25]  arXiv:1806.08118 [pdf, other]
Title: Localised response retrieval from Hamamatsu H9500 for a coded aperture neutron-gamma imaging system based on an organic pixelated plastic scintillator (EJ-299-34)
Comments: 21st IEEE Real Time Conference, Colonial Williamsburg, USA, June 2018
Subjects: Instrumentation and Detectors (physics.ins-det)

Localised response of a sensitive light detector, such as Hamamatsu H9500 multi anode photomultiplier tube (MAPMT), is of vital importance for coded-aperture imaging systems. When coupled with a suitable sensitive detector (e.g. EJ-299-34 plastic scintillator), output signals of the MAPMT can be retrieved to infer the interaction location in the pixelated scintillator. Given the number of anodes in H9500 (256), significant processing power would be necessary to handle each pulse individually. Therefore, a readout electronics system was developed, based on resistive network approach, which reduces the number of output signals to individual X and Y coordinates, and subsequently allows particle identification. Coordinates retrieved in this manner can be analysed in real time and used to infer the two-dimensional location. Particle type can be also exploited by pulse shape discrimination (PSD) application to the scintillator response. In this study, 169 anodes were used (due to coded-aperture design rules), and reduced to two X and Y output signals. These have been digitised using a bespoke FPGA based two channel 14-bit 150 MSPS digitiser. The digital data are transferred to a host application using UART to USB converter operating at 12 Mbits/s. Promising results have been observed when the scintillator's response was tested in single particle field of Cs-137. However, further tests performed in the mixed-field environment of Cf-252 suggest that faster digitiser may be required to obtain the required PSD performance.

[26]  arXiv:1806.08123 [pdf]
Title: Symmetry Breaking of Kramers-Henneberger Atoms by Ponderomotive Force
Authors: Qi Wei
Comments: 7 pages
Subjects: Optics (physics.optics); Atomic Physics (physics.atom-ph)

It was believed that Kramers-Henneberger atoms in superintense laser field exhibit structure of "dichotomy". However this is not true for focused laser field. Because in focused laser, KH state electrons experience ponderomotive force, which will break the dichotomous structure.

[27]  arXiv:1806.08157 [pdf, other]
Title: Resistively-limited current sheet implosions in planar anti-parallel (1D) and null-point containing (2D) magnetic field geometries
Comments: Accepted, will be published Open Access in Physics of Plasmas - refer to main journal for animations
Subjects: Plasma Physics (physics.plasm-ph); Solar and Stellar Astrophysics (astro-ph.SR); Fluid Dynamics (physics.flu-dyn)

Implosive formation of current sheets is a fundamental plasma process. Previous studies focused on the early time evolution, while here our primary aim is to explore the longer-term evolution, which may be critical for determining the efficiency of energy release. To address this problem we investigate two closely-related problems, namely: (i) 1D, pinched anti-parallel magnetic fields and (ii) 2D, null point containing fields which are locally imbalanced ('null-collapse' or 'X-point collapse'). Within the framework of resistive MHD, we simulate the full nonlinear evolution through three distinct phases: the initial implosion, its eventual halting mechanism, and subsequent evolution post-halting. In a parameter study, we find the scaling with resistivity of current sheet properties at the halting time is in good agreement - in both geometries - with that inferred from a known 1D similarity solution. We find that the halting of the implosions occurs rapidly after reaching the diffusion scale by sudden Ohmic heating of the dense plasma within the current sheet, which provides a pressure gradient sufficient to oppose further collapse and decelerate the converging flow. This back-pressure grows to exceed that required for force balance and so the post-implosion evolution is characterised by the consequences of the current sheet `bouncing' outwards. These are: (i) the launching of propagating fast MHD waves (shocks) outwards and (ii) the width-wise expansion of the current sheet itself. The expansion is only observed to stall in the 2D case, where the pressurisation is relieved by outflow in the reconnection jets. In the 2D case, we quantify the maximum amount of current sheet expansion as it scales with resistivity, {and analyse the structure of the reconnection region which forms post-expansion, replete with Petschek-type slow shocks and fast termination shocks.

[28]  arXiv:1806.08162 [pdf, other]
Title: The electrical conductivity tensor of $β$-Ga$_{2}$O$_{3}$ analyzed by van der Pauw measurements: Inherent anisotropy, off-diagonal element, and the impact of grain boundaries
Subjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)

The semiconducting oxide $\beta$-Gallium Oxide ($\beta$-Ga$_{2}$O$_{3}$) possesses a monoclinic unit cell whose low symmetry generally leads to anisotropic physical properties. For example, its electrical conductivity is generally described by a polar symmetrical tensor of second rank consisting of four independent components. Using van der Pauw measurements in a well-defined square geometry on differently-oriented high-quality bulk samples and the comparison to finite element simulations we determine the ratio of all elements of the $\beta$-Ga$_{2}$O$_{3}$ 3-dimensional electrical conductivity tensor. Despite the structural anisotropy a nearly isotropic conductivity was found with the principal conductivities deviating from each other by less than 5 % and the off-diagonal element being less than 4 % of the diagonal ones. Analysis of the temperature dependence of the anisotropy and mobility of differently doped samples suggest this isotropic behavior to apply for phonon-scattering as well as ionized-impurity scattering. We demonstrate that significantly higher anisotropies can be caused by extended structural defects in the form of low-angle grain boundaries for which we determined energy barriers of multiple 10 meV.

[29]  arXiv:1806.08172 [pdf]
Title: Sub-20 nm Nanopores Sculptured by a Single Nanosecond Laser Pulse
Comments: The work of this paper was done in 2013
Subjects: Biological Physics (physics.bio-ph)

Single-molecule based 3rd generation DNA sequencing technologies have been explored with tremendous effort, among which nanopore sequencing is considered as one of the most promising to achieve the goal of $1,000 genome project towards personalized medicine. Solid state nanopore is consented to be complementary to protein nanopore and subjected to extensive investigations in the past decade. However, the prevailing solid-state nanopore preparation still relies on focused ion or electron beams, which are expensive and time consuming. Here we demonstrate the fabrication of nanopores down to 19 nm with a single nanosecond laser pulse. The laser drilling process is understood based upon a 2D axisymmetric transient heat transfer model, which predicts the laser fluence-dependent pore size distribution and shape with excellent agreement to electron microscopy and tomography analysis. As-drilled nanopore devices (26 nm) exhibit adequate sensitivity to detect single DNA molecule translocations and discriminate unfolded or folded events. Sub-10 nm nanopores can be readily achieved upon a thin layer of alumina deposition by atomic layer deposition, which further improves the DNA translocation signal to noise ratio considerably. Our work provides a solution for fast, low-cost and efficient large-scale fabrication of solid state nanopore devices for the 3rd generation nanopore sequencing.

[30]  arXiv:1806.08179 [pdf]
Title: Classification of red blood cell shapes in flow using outlier tolerant machine learning
Comments: 15 pages, published in PLoS Comput Biol, open access
Journal-ref: PLoS Comput Biol. 2018 Jun 15;14(6):e1006278
Subjects: Biological Physics (physics.bio-ph); Fluid Dynamics (physics.flu-dyn); Other Quantitative Biology (q-bio.OT)

The manual evaluation, classification and counting of biological objects demands for an enormous expenditure of time and subjective human input may be a source of error. Investigating the shape of red blood cells (RBCs) in microcapillary Poiseuille flow, we overcome this drawback by introducing a convolutional neural regression network for an automatic, outlier tolerant shape classification. From our experiments we expect two stable geometries: the so-called `slipper' and `croissant' shapes depending on the prevailing flow conditions and the cell-intrinsic parameters. Whereas croissants mostly occur at low shear rates, slippers evolve at higher flow velocities. With our method, we are able to find the transition point between both `phases' of stable shapes which is of high interest to ensuing theoretical studies and numerical simulations. Using statistically based thresholds, from our data, we obtain so-called phase diagrams which are compared to manual evaluations. Prospectively, our concept allows us to perform objective analyses of measurements for a variety of flow conditions and to receive comparable results. Moreover, the proposed procedure enables unbiased studies on the influence of drugs on flow properties of single RBCs and the resulting macroscopic change of the flow behavior of whole blood.

[31]  arXiv:1806.08180 [pdf]
Title: Upgrade of the Data Acquisition and Control System of Microwave Reflectometry on the Experimental Advanced Superconducting Tokamak
Comments: 21st IEEE Real Time Conference
Subjects: Instrumentation and Detectors (physics.ins-det)

The reflectometry on Experimental Advanced Superconducting Tokamak (EAST) is undergoing an upgrade for more comprehensive measurement of plasma density profile and fluctuation. The Data Acquisition and Control System (DACS) has been redeveloped to satisfy the requirements of the upgraded reflectometry. The profile reflectometry works in 30-110 GHz (X-mode) and 40-90GHz (O-mode), when the fluctuation reflectometry operates at 20 fixed frequency points in 50-110GHz (X-mode) and 20-60GHz (O-mode). The PXIe-based DACS includes two 8-channel 14-bit 250MSPS digitizers and ten 8-channel 12-bit 60MSPS digitizers. A self-developed 5-channel 250MSPS arbiter waveform generator (AWG) is used to control voltage control oscillators for frequency sweeping. A trigger and clock manger and a timing module receive the trigger and clock signal from central controller and synchronize all the digitizers and the AWG. The total data rate from digitizers is 2515 MB/S. The Data from digitizers is streamed to a disk array (RAID 0) with data throughput capacity of 3000 MB/S. Meanwhile, selected data is transported to a FPGA based real-time data processing module, which utilize a pre-trained neural network to calculate the plasma density profile. Now the new reflectometry is being installed on EAST, and its performance will be tested in experimental campaign after 2018.

[32]  arXiv:1806.08188 [pdf, ps, other]
Title: Enhanced Absorption of Waves in Hyperuniform Disordered Media
Subjects: Optics (physics.optics)

We study the propagation of waves in a set of absorbing subwavelength scatterers positioned on a stealth hyperuniform point pattern. We show that spatial correlations in the disorder substantially enhance absorption compared to a fully disordered structure with the same density of scatterers. The non-resonant nature of the mechanism provides broad angular and spectral robustness. These results open perspectives in the design of low-density disordered materials with blackbody-like absorption.

[33]  arXiv:1806.08193 [pdf, other]
Title: Real-time non-intrusive depth estimation of buried radioactive wastes based on approximate three-dimensional relative attenuation model
Comments: 21st IEEE Real Time Conference, Colonial Williamsburg, USA, June 2018
Subjects: Instrumentation and Detectors (physics.ins-det)

A new method for non-intrusive estimation of the depth of buried radioactive waste have been developed. The method is based on an approximate three-dimensional relative attenuation model that exploits the variation in the intensities of the radiation image obtained on the surface of the material in which the radioactive source is buried. Experimental results using an organic liquid scintillator detector showed that the method is able to estimate the depth of a 329 kBq Cs-137 radioactive point source buried up to 12 cm in sand.

[34]  arXiv:1806.08207 [pdf, other]
Title: Fractal dimensions and trajectory crossings in correlated random walks
Comments: 11 pages, 5 figures
Subjects: Fluid Dynamics (physics.flu-dyn)

We study spatial clustering in a discrete, one-dimensional, stochastic, toy model of heavy particles in turbulence and calculate the spectrum of multifractal dimensions $D_q$ as functions of a dimensionless parameter, $\alpha$, that plays the role of an inertia parameter. Using the fact that it suffices to consider the linearized dynamics of the model at small separations, we find that $D_q =D_2/(q-1)$ for $q=2,3,\ldots$. The correlation dimension $D_2$ turns out to be a non-analytic function of the inertia parameter in this model. We calculate $D_2$ for small $\alpha$ up to the next-to-leading order in the non-analytic term.

[35]  arXiv:1806.08220 [pdf, ps, other]
Title: A unified theory for both massless, massive vector fields and non-triviality of physical Hilbert space of this theory
Authors: Susobhan Mandal
Comments: 8 pages
Subjects: General Physics (physics.gen-ph); High Energy Physics - Theory (hep-th)

In this article, I talk about a model which is known and often used to unify both massless and massive vector free-field theory, discuss the importance of auxiliary scalar field introduced in the Lagrangian density that we consider in this theory which turns out to be unphysical in massive vector field case which I also show. But for massless theory in 3+1-dimensional case, I show that this auxiliary field makes the physical Hilbert space non-trivial in terms of introducing an extra physical degree of freedom or an extra non-trivial kind of polarized state which is absent in Maxwell's electrodynamics theory (free-massless vector field theory). And this state is also shown to be present in 1+1-dimensional theory whereas there is no on-shell photon in Maxwell's theory of electromagnetism, which is a massless vector field theory.

[36]  arXiv:1806.08221 [pdf, ps, other]
Title: Quaternionic approach to dual Magneto-hydrodynamics of dyonic cold plasma
Comments: 20 pages
Subjects: General Physics (physics.gen-ph)

The dual magneto-hydrodynamics of dyonic plasma describes the study of electrodynamics equations along with the transport equations in the presence of electrons and magnetic monopoles. In this paper, we formulate the quaternionic dual fields equations, namely, the hydro-electric and hydro-magnetic fields equations which are an analogous to the generalized Lamb vector field and vorticity field equations of dyonic cold plasma. Further, we derive the quaternionic Dirac-Maxwell equations for dual magneto-hydrodynamics of dyonic cold plasma. We also obtain the quaternionic dual continuity equations that describe the transport of dyonic fluid. Finally, we establish an analogy of Alfven wave equation which may relate one of the flow of magnetic monopoles in the dyonic cold plasma. The present quaternionic formulation for dyonic cold plasma is well invariant under the duality, Lorentz and CPT transformations.

[37]  arXiv:1806.08222 [pdf, other]
Title: Time in quantum mechanics and the local non-conservation of the probability current
Authors: G. Modanese
Comments: 16 pages, 5 figures
Subjects: General Physics (physics.gen-ph)

In relativistic quantum field theory with local interactions, charge is locally conserved. This implies local conservation of probability for the Dirac and Klein-Gordon wavefunctions, as special cases; and then in turn for non-relativistic quantum field theory and for the Schroedinger and Ginzburg-Landau equations, regarded as low energy limits. Quantum mechanics, however, is wider than quantum field theory, as an effective model of reality. For instance, fractional quantum mechanics and Schroedinger equations with non-local terms have been successfully employed in several applications. The non-locality of these formalisms is strictly related to the problem of time in quantum mechanics. We compute explicitly for continuum wave packets the terms of the fractional Schroedinger equation and of the non-local Schroedinger equation by Lenzi et al. which break the local current conservation, and discuss their physical significance. The results are especially relevant for the electromagnetic coupling of these wavefunctions. A connection with the non-local Gorkov equation for superconductors and their proximity effect is also outlined.

[38]  arXiv:1806.08228 [pdf, other]
Title: Electro-Neutral Models for dynamic Poisson-Nernst-Planck System: 2D Case
Comments: arXiv admin note: text overlap with arXiv:1711.07562
Subjects: Biological Physics (physics.bio-ph)

The Poisson-Nernst-Planck (PNP) system is a standard model for describing ion transport. In many applications, e.g., ions in biological tissues, the presence of thin boundary layers poses both modelling and computational challenges. In a previous paper, we derived simplified electro-neutral (EN) models in one dimensional space where the thin boundary layers are replaced by effective boundary conditions. In this paper, we extend our analysis to the two dimensional case where the EN model enjoys even greater advantages. First of all, it is much cheaper to solve the EN models numerically. Secondly, EN models are easier to deal with compared with the original PNP system, therefore it is also easier to derive macroscopic models for cellular structures using EN models. The multi-ion case with general boundary is considered, for a variety of boundary conditions including either Dirichlet or flux boundary conditions. Using systematic asymptotic analysis, we derive a variety of effective boundary conditions directly applicable to the EN system for the bulk region. To validate the EN models, numerical computations are carried out for both the EN and original PNP system, including the propagation of action potential for both myelinated and unmyelinated axons. Our results show that solving the EN models is much more efficient than the original PNP system.

[39]  arXiv:1806.08234 [pdf, other]
Title: Neural Networks as Globally Optimal Multilayer Convolution Architectures for Learning Fluid Flows
Comments: Article in review. arXiv admin note: text overlap with arXiv:1805.12547 by other authors
Subjects: Computational Physics (physics.comp-ph)

In this work we explore globally optimal multilayer convolution models such as feed forward neural-networks (FFNN) for learning and predicting dynamics from transient fluid flow data. While machine learning in general depends on data quality relative to the underlying dynamics of the system, it is important for a given data-driven learning architecture to make the most of this available information. To this end, we cast the suite of recently popular data-driven learning approaches that approximate the Markovian dynamics through a linear model in a higher-dimensional feature space as a multilayer architecture similar to neural networks, but with layer-wise locally optimal convolution mappings. As a contrast, we also represent the traditional neural networks with some slight modifications as a multilayer architecture, but with convolution maps optimized in response to the global learning cost (i.e. not the cost of learning across two immediate layers). We show through examples of data-driven learning of canonical fluid flows that globally optimal FFNN-like methods owe their success to leveraging the extended learning parameter space available in multilayer models to achieve a common goal of minimizing the training cost function while incorporating nonlinear function maps between layers. On the other hand, locally optimal multilayer models also show improvement from the same factors, but behave like shallow neural networks requiring much larger hidden layers to achieve comparable learning and prediction accuracy. We illustrate these ideas by learning the dynamics from snapshots of training data and predicting the temporal evolution of canonical nonlinear fluid flows.

[40]  arXiv:1806.08259 [pdf, other]
Title: Dynamic Network 3 -- 0 FIFA Rankings: Replacing an inaccurate, biased, and exploitable football ranking system
Authors: Sam Abernethy
Subjects: Physics and Society (physics.soc-ph); Social and Information Networks (cs.SI)

International football results are interpreted as a directed network to give each team a rank. Two network-based models --- Static and Dynamic --- are constructed and compared with the current FIFA Rankings. The Dynamic Model outperforms the FIFA Rankings in terms of World Cup predictive accuracy, while also removing continental bias and reducing the vulnerability of the FIFA Rankings to exploitation. This is done using two intuitive parameters --- relative importance of indirect wins and bygone wins --- whose values are determined to be 0.07 and 0.9 respectively. We suggest that FIFA should implement this model as its future ranking system.

[41]  arXiv:1806.08265 [pdf, other]
Title: Development and Characterization of 6-gap Bakelite Multi-gap Resistive Plate Chamber
Subjects: Instrumentation and Detectors (physics.ins-det)

The Multi-gap Resistive Plate Chamber (MRPC) is an advanced form of Resistive Plate Chamber (RPC) detector where the gas gap is divided into sub-gaps. MRPCs are known for their good time resolution and detection efficiency for charged particles. They have found suitable applications in several high energy physics experiments like ALICE in LHC, CERN, Geneva, Switzerland, and STAR in RHIC, BNL, USA. As they have very good time resolution and are of low cost, they can be a suitable replacement for very expensive scintillators used in Positron Emission Tomography Imaging. The MRPCs that are being used nowadays are developed with glass electrodes. We have made an attempt to develop a 6-gap MRPC using bakelite electrodes. The outer electrodes are of dimensions 15 cm $\times$ 15 cm $\times$ 0.3 cm and the inner electrodes are of dimension 14 cm $\times$ 14 cm $\times$ 0.05 cm. The glossy finished electrode surfaces have not been treated with any oil like linseed, silicone for smoothness. The performance of the detector has been studied measuring the efficiency, noise rate and time resolution with cosmic rays. This effort is towards the development of a prototype for Positron Emission Tomography with the Time-Of-Flight technique using MRPCs. Details of the development procedure and performance studies have been presented here.

[42]  arXiv:1806.08280 [pdf]
Title: Fourier plane optical microscopy and spectroscopy
Comments: Submitted to Wiley VCH encyclopedia of applied physics
Subjects: Optics (physics.optics); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Applied Physics (physics.app-ph)

Intensity, wavevector, phase, and polarization are the most important parameters of any light beam. Understanding the wavevector distribution has emerged as a very important problem in recent days, especially at nanoscale. It provides unique information about the light-matter interaction. Back focal plane or Fourier plane imaging and spectroscopy techniques help to measure wavevector distribution not only from single molecules and single nanostructures but also from metasurfaces and metamaterials. This review provides a birds-eye view on the technique of back focal imaging and spectroscopy, different methodologies used in developing the technique and applications including angular emission patterns of fluorescence and Raman signals from molecules, elastic scattering etc. We first discuss on the information one can obtain at the back focal plane of the objective lens according to both imaging and spectroscopy viewpoints and then discuss the possible configurations utilized to project back focal plane of the objective lens onto the imaging camera or to the spectroscope. We also discuss the possible sources of error in such measurements and possible ways to overcome it and then elucidate the possible applications.

[43]  arXiv:1806.08285 [pdf, other]
Title: Photons in the presence of parabolic mirrors
Comments: 23 pages, 5 figures
Subjects: Optics (physics.optics); Quantum Physics (quant-ph)

We present a vectorial analysis of the behavior of the electromagnetic field in the presence of boundaries with parabolic geometry. The relevance of the use of symmetries to find explicit closed expressions for the electromagnetic fields is emphasized. Polarization and phase related angular momenta of light have an essential role in the proper definition of the generator $\mathfrak{A}_3$ of a symmetry transformation that distinguishes the parabolic geometry. Quantization of the electromagnetic field in terms of the resulting elementary modes is performed. The important case of a boundary defined by an ideal parabolic mirror is explicitly worked out. The presence of the mirror restricts the eigenvalues of $\mathfrak{A}_3$ available to the electric and magnetic fields of a given mode via compact expressions. Modes previously reported in the literature are particular cases of those described in this work.

[44]  arXiv:1806.08289 [pdf, ps, other]
Title: Magnon-induced high-order sideband generation
Comments: 5 pages, 4 figures
Subjects: Optics (physics.optics)

Magnon Kerr nonlinearity plays crucial roles in the study of cavity optomagnonics system and may bring many novel physical phenomena and important applications. In this work, we report the investigation of high- order sideband generation induced by magnon Kerr nonlinearity in a cavity-magnon system, which is critically lacking in this emerging research field. We uncover that the driving field plays a significant role in controlling the generation and amplification of the higher-order sidebands and the sideband spacing can be adjusted by regulating the beat frequency between the pump laser and the probe laser, which is extremely eventful for the spacing modulation of the sideband spectrum. Based on the recent experimental progress, our results deepen our cognition into optomagnonics nonlinearity and may find interesting applications in optical frequency metrology and optical communications.

[45]  arXiv:1806.08293 [pdf, other]
Title: Beam tests of silicon pixel 3D-sensors developed at SINTEF
Subjects: Instrumentation and Detectors (physics.ins-det)

For the purpose of withstanding very high radiation doses, silicon pixel sensors with a 3D electrode geometry are being developed. Detectors of this kind are highly interesting for harch radiation environments such as expected in the High Luminosity LHC, but also for space physics and medical applications. In this paper, prototype sensors developed at SINTEF are presented and results from tests in a pion beam at CERN are given. These tests shows that these 3D sensors perform as expected with full efficiency at bias voltages between 5 and 15V.

[46]  arXiv:1806.08312 [pdf, other]
Title: The KATRIN Superconducting Magnets: Overview and First Performance Results
Subjects: Instrumentation and Detectors (physics.ins-det)

The KATRIN experiment aims for the determination of the effective electron anti-neutrino mass from the tritium beta-decay with an unprecedented sub-eV sensitivity. The strong magnetic fields, designed for up to 6~T, adiabatically guide $\beta$-electrons from the source to the detector within a magnetic flux of 191~Tcm$^2$. A chain of ten single solenoid magnets and two larger superconducting magnet systems have been designed, constructed, and installed in the 70-m-long KATRIN beam line. The beam diameter for the magnetic flux varies from 0.064~m to 9~m, depending on the magnetic flux density along the beam line. Two transport and tritium pumping sections are assembled with chicane beam tubes to avoid direct "line-of-sight" molecular beaming effect of gaseous tritium molecules into the next beam sections. The sophisticated beam alignment has been successfully cross-checked by electron sources. In addition, magnet safety systems were developed to protect the complex magnet systems against coil quenches or other system failures. The main functionality of the magnet safety systems has been successfully tested with the two large magnet systems. The complete chain of the magnets was operated for several weeks at 70$\%$ of the design fields for the first test measurements with radioactive krypton gas. The stability of the magnetic fields of the source magnets has been shown to be better than 0.01$\%$ per month at 70$\%$ of the design fields. This paper gives an overview of the KATRIN superconducting magnets and reports on the first performance results of the magnets.

[47]  arXiv:1806.08314 [pdf]
Title: Coherent multidimensional spectroscopy of dilute gas-phase nanosystems
Subjects: Chemical Physics (physics.chem-ph)

Two-dimensional electronic spectroscopy (2DES) is one of the most powerful spectroscopic techniques, capable of attaining a nearly complete picture of a quantum system including its couplings, quantum coherence properties and its real-time dynamics. While successfully applied to a variety of condensed phase samples, high precision experiments on isolated quantum systems in the gas phase have been so far precluded by insufficient sensitivity. However, such experiments are essential for a precise understanding of fundamental mechanisms and to avoid misinterpretations, e.g. as for the nature of quantum coherences in energy trans-port. Here, we solve this issue by extending 2DES to isolated nanosystems in the gas phase prepared by helium nanodroplet isolation in a molecular beam-type experiment. This approach uniquely provides high flexibility in synthesizing tailored, quantum state-selected model systems of single and many-body properties. For demonstration, we deduce a precise and conclusive picture of the ultrafast coherent dynamics in isolated high-spin Rb2 molecules and present for the first time a dynamics study of the system-bath interaction between a single molecule (here Rb3) and a superfluid helium environment. The results demonstrate the unique capacity to elucidate prototypical interactions and dynamics in tailored quantum systems and bridges the gap to experiments in ultracold quantum science.

[48]  arXiv:1806.08318 [pdf, other]
Title: Diffusion vs. direct transport in the precision of morphogen readout
Subjects: Biological Physics (physics.bio-ph); Cell Behavior (q-bio.CB)

Morphogen profiles allow cells to determine their position within a developing organism, but the mechanisms behind the formation of these profiles are still not well agreed upon. Here we derive fundamental limits to the precision of morphogen concentration sensing for two canonical models: the diffusion of morphogen through extracellular space and the direct transport of morphogen from source cell to target cell, e.g. via cytonemes. We find that direct transport establishes a morphogen profile without adding extrinsic noise. Despite this advantage, we find that for sufficiently large values of population size and profile length, the diffusion mechanism is many times more precise due to a higher refresh rate of morphogen molecules. Our predictions are supported by data from a wide variety of morphogens in developing organisms.

[49]  arXiv:1806.08326 [pdf, other]
Title: Changes in the boundary-layer structure at the edge of the ultimate regime in vertical natural convection
Journal-ref: J. Fluid Mech. 825 (2017) 550-572
Subjects: Fluid Dynamics (physics.flu-dyn)

In thermal convection for very large Rayleigh numbers ($Ra$), the thermal and viscous boundary layers (BL) undergo a transition from a classical state to an ultimate state. In the former state, the BL thicknesses follow a laminar-like Prandtl-Blasius-Polhausen scaling, whereas in the latter, the BLs are turbulent with log-corrections in the sense of Prandtl and von K\'arm\'an. Here, we report evidence of this transition via changes in the BL structure of vertical natural convection (VC), which is a buoyancy driven flow between differentially heated vertical walls. The dataset spans $Ra$-values from $10^5$ to $10^9$ and Prandtl number value of 0.709. For this $Ra$ range, the VC flow exhibits classical state behaviour in a global sense. Yet, with increasing $Ra$, we observe that near-wall higher-shear patches occupy increasingly larger fractions of the wall-areas, which suggest that the BLs are undergoing a transition from the classical state to the ultimate shear-dominated state. The presence of streaky structures-reminiscent of the near-wall streaks in canonical wall-bounded turbulence-further supports the notion of this transition. Within the higher-shear patches, conditionally averaged statistics yield a log-variation in the local mean temperature profiles, in agreement with the log-law of the wall for mean temperature, and a $Ra^{0.37}$ effective power-law scaling of the local Nusselt number, consistent with the logarithmically corrected 1/2-power law scaling predicted for ultimate thermal convection for very large $Ra$. Collectively, the results from this study indicate that turbulent and laminar-like BL coexist in VC at moderate to high $Ra$ and this transition from the classical state to the ultimate state manifests as increasingly larger shear-dominated patches, consistent with the findings reported for Rayleigh-B\'enard convection and Taylor-Couette flows.

[50]  arXiv:1806.08341 [pdf, other]
Title: Bulk scaling in wall-bounded and homogeneous vertical natural convection
Journal-ref: J. Fluid Mech. 841 (2018) 825-850
Subjects: Fluid Dynamics (physics.flu-dyn)

Previous numerical studies on homogeneous Rayleigh-B\'enard convection, which is Rayleigh-B\'enard convection (RBC) without walls, and therefore without boundary layers, have revealed a scaling regime that is consistent with theoretical predictions of bulk-dominated thermal convection. In this so-called asymptotic regime, previous studies have predicted that the Nusselt number ($Nu$) and the Reynolds number ($Re$) vary with the Rayleigh number ($Ra$) according to $Nu\sim Ra^{1/2}$ and $Re\sim Ra^{1/2}$ at small Prandtl number ($Pr$). In this study, we consider a flow that is similar to RBC but with the direction of temperature gradient perpendicular to gravity instead of parallel; we refer to this configuration as vertical natural convection (VC). Since the direction of the temperature gradient is different in VC, there is no exact relation for the average kinetic dissipation rate, which makes it necessary to explore alternative definitions for $Nu$, $Re$ and $Ra$ and to find physical arguments for closure, rather than making use of the exact relation between $Nu$ and the dissipation rates as in RBC. Once we remove the walls from VC to obtain the homogeneous setup, we find that the aforementioned $1/2$-power-law scaling is present, similar to the case of homogeneous RBC. When focussing on the bulk, we find that the Nusselt and Reynolds numbers in the bulk of VC too exhibit the $1/2$-power-law scaling. These results suggest that the $1/2$-power-law scaling may even be found at lower Rayleigh numbers if the appropriate quantities in the turbulent bulk flow are employed for the definitions of $Ra$, $Re$ and $Nu$. From a stability perspective, at low- to moderate-$Ra$, we find that the time-evolution of the Nusselt number for homogenous vertical natural convection is unsteady, which is consistent with the nature of the elevator modes reported in previous studies on homogeneous RBC.

Cross-lists for Fri, 22 Jun 18

[51]  arXiv:1806.07879 (cross-list from q-bio.NC) [pdf, ps, other]
Title: Integrated information in the thermodynamic limit
Comments: arXiv admin note: substantial text overlap with arXiv:1805.00393
Subjects: Neurons and Cognition (q-bio.NC); Disordered Systems and Neural Networks (cond-mat.dis-nn); Statistical Mechanics (cond-mat.stat-mech); Adaptation and Self-Organizing Systems (nlin.AO); Biological Physics (physics.bio-ph)

The ability to integrate information into a unified coherent whole is a fundamental capacity of many biological and cognitive systems. Integrated Information Theory (IIT) provides a mathematical approach to quantify the level of integration in a system. Nevertheless, it is not yet well understood how integration scales up with the size of a system or with different temporal scales of activity, nor how a system maintains its integration as its interacts with its environment. We argue that modelling and understanding how measures of information integration operate in these scenarios is fundamental to adequately capture integration in systems such as the brain. We propose a simplified and modified version of integrated information {\phi} in order to explore these questions. Using mean field approximations, we measure {\phi} in a kinetic Ising models of infinite size. We find that information integration diverges in some cases when the system is near critical points in continuous phase transitions. Moreover, we find that we can delimit the boundary of a system with respect to its environment by comparing the divergent integrative tendencies of system and system-environment processes respectively. Finally, we model a system that maintains integrated information when interacting with a range of different environments by generating a critical surface spanning a parametric region of the environment. We conclude by discussing how thinking about integrated information in the thermodynamic limit opens fruitful research avenues for studying the organization of biological and cognitive systems.

[52]  arXiv:1806.07903 (cross-list from q-bio.NC) [pdf, other]
Title: Finding influential nodes for integration in brain networks using optimal percolation theory
Comments: 20 pages, 6 figures, Supplementary Info
Journal-ref: Nature Communications, 9, 2274, (2018)
Subjects: Neurons and Cognition (q-bio.NC); Disordered Systems and Neural Networks (cond-mat.dis-nn); Biological Physics (physics.bio-ph)

Global integration of information in the brain results from complex interactions of segregated brain networks. Identifying the most influential neuronal populations that efficiently bind these networks is a fundamental problem of systems neuroscience. Here we apply optimal percolation theory and pharmacogenetic interventions in-vivo to predict and subsequently target nodes that are essential for global integration of a memory network in rodents. The theory predicts that integration in the memory network is mediated by a set of low-degree nodes located in the nucleus accumbens. This result is confirmed with pharmacogenetic inactivation of the nucleus accumbens, which eliminates the formation of the memory network, while inactivations of other brain areas leave the network intact. Thus, optimal percolation theory predicts essential nodes in brain networks. This could be used to identify targets of interventions to modulate brain function.

[53]  arXiv:1806.07909 (cross-list from gr-qc) [pdf, other]
Title: Black hole binaries: ergoregions, photon surfaces, wave scattering, and quasinormal modes
Comments: 13 pages, 11 figures
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th); Fluid Dynamics (physics.flu-dyn)

The photon surface of isolated black holes is related to important aspects of black hole physics, such as strong lensing, absorption cross section of null particles and the way that black holes relax through quasinormal ringing. When two black holes are present -- such as during the inspiral and merger events of interest for gravitational-wave detectors -- the concept of a photon surface still exists, but its properties are basically unknown. With these applications in mind, we study here the photon surface of two different static black hole binaries. The first one is the Majumdar-Papapetrou geometry describing two extremal, charged black holes in equilibrium, while the second one is the double sink solution of fluid dynamics, which describes (in a curved-spacetime language) two "dumb" holes. For the latter solution, we also characterize its dynamical response to external perturbations, and study how it relates to the photon surface structure. In addition, we compute the ergoregion of such spacetime and show that it does not coincide with the event horizon.

[54]  arXiv:1806.07925 (cross-list from quant-ph) [pdf]
Title: There Is No Action at a Distance in Quantum Mechanics, Spooky or Otherwise
Authors: Stephen Boughn
Comments: 9 pages
Subjects: Quantum Physics (quant-ph); History and Philosophy of Physics (physics.hist-ph)

I feel compelled to respond to the frequent references to spooky action at a distance that often accompany reports of experiments investigating entangled quantum mechanical states. Most, but not all, of these articles have appeared in the popular press. As an experimentalist I have great admiration for such experiments and the concomitant advances in quantum information and quantum computing, but accompanying claims of action at a distance are quite simply nonsense. Some physicists and philosophers of science have bought into the story by promoting the nonlocal nature of quantum mechanics. In 1964, John Bell proved that classical hidden variable theories cannot reproduce the predictions of quantum mechanics unless they employ some type of action at a distance. I have no problem with this conclusion. Unfortunately, Bell later expanded his analysis and mistakenly deduced that quantum mechanics and by implication nature herself are nonlocal. In addition, some of these articles present Einstein in caricature, a tragic figure who neither understood quantum mechanics nor believed it to be an accurate theory of nature. Consequently, the current experiments have proven him wrong. This is also nonsense.

[55]  arXiv:1806.07947 (cross-list from math.CA) [pdf, ps, other]
Title: Simply improved averaging for coupled oscillators and weakly nonlinear waves
Authors: Molei Tao
Comments: Comments are welcomed
Subjects: Classical Analysis and ODEs (math.CA); Computational Physics (physics.comp-ph)

The long time effect of nonlinear perturbation to oscillatory linear systems can be characterized by the averaging method, and we consider first-order averaging for its simplest applicability to high-dimensional problems. Instead of the classical approach, in which one uses the pullback of linear flow to isolate slow variables and then approximate the effective dynamics by averaging, we propose an alternative coordinate transform that better approximates the mean of oscillations. This leads to a simple improvement of the averaged system, which will be shown both theoretically and numerically to provide a more accurate approximation. Three examples are then provided: in the first, a new device for wireless energy transfer modeled by two coupled oscillators was analyzed, and the results provide design guidance and performance quantification for the device; the second is a classical coupled oscillator problem (Fermi-Pasta-Ulam), for which we numerically observed improved accuracy beyond the theoretically justified timescale; the third is a nonlinearly perturbed first-order wave equation, which demonstrates the efficacy of improved averaging in an infinite dimensional setting.

[56]  arXiv:1806.07956 (cross-list from cs.SI) [pdf, other]
Title: Reconstructing networks with unknown and heterogeneous errors
Authors: Tiago P. Peixoto
Comments: 27 pages, 17 figures
Subjects: Social and Information Networks (cs.SI); Learning (cs.LG); Data Analysis, Statistics and Probability (physics.data-an); Machine Learning (stat.ML)

The vast majority of network datasets contains errors and omissions, although this is rarely incorporated in traditional network analysis. Recently, an increasing effort has been made to fill this methodological gap by developing network reconstruction approaches based on Bayesian inference. These approaches, however, rely on assumptions of uniform error rates and on direct estimations of the existence of each edge via repeated measurements, something that is currently unavailable for the majority of network data. Here we develop a Bayesian reconstruction approach that lifts these limitations by not only allowing for heterogeneous errors, but also for individual edge measurements without direct error estimates. Our approach works by coupling the inference approach with structured generative network models, which enable the correlations between edges to be used as reliable error estimates. Although our approach is general, we focus on the stochastic block model as the basic generative process, from which efficient nonparametric inference can be performed, and yields a principled method to infer hierarchical community structure from noisy data. We demonstrate the efficacy of our approach with a variety of empirical and artificial networks.

[57]  arXiv:1806.08018 (cross-list from quant-ph) [pdf, other]
Title: Full characterization of a high-dimensional quantum communication channel
Comments: 7 pages, 4 figures
Subjects: Quantum Physics (quant-ph); Optics (physics.optics)

The characterization of quantum processes, e.g. communication channels, is an essential ingredient for establishing quantum information systems. For quantum key distribution protocols, the amount of overall noise in the channel determines the rate at which secret bits are distributed between authorized partners. In particular, tomographic protocols allow for the full reconstruction, and thus characterization, of the channel. Here, we perform quantum process tomography of high-dimensional quantum communication channels with dimensions ranging from 2 to 5. We can thus explicitly demonstrate the effect of an eavesdropper performing an optimal cloning attack or an intercept-resend attack during a quantum cryptographic protocol. Our study shows that the process matrix enables a more detailed understanding of the channel conditions compared to a coarse-grained measure, such as quantum bit error rates. This full characterization technique allows us to distinguish eavesdropping attempts and optimize the quantum key distribution performance under asymmetric experimental conditions.

[58]  arXiv:1806.08116 (cross-list from cond-mat.mtrl-sci) [pdf]
Title: The structure of near stoichiometric Ge-Ga-Sb-S glasses: a reverse Monte Carlo study
Comments: 23 pages, 5 figures, submitted to Journal of Non-crystalline Solids
Subjects: Materials Science (cond-mat.mtrl-sci); Disordered Systems and Neural Networks (cond-mat.dis-nn); Chemical Physics (physics.chem-ph)

The structure of Ge$_{22}$Ga$_3$Sb$_{10}$S$_{65}$ and Ge$_{15}$Ga$_{10}$Sb$_{10}$S$_{65}$ glasses was investigated by neutron diffraction (ND), X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS) measurements at the Ge, Ga and Sb K-edges. Experimental data sets were fitted simultaneously in the framework of the reverse Monte Carlo (RMC) simulation technique. Short range order parameters were determined from the obtained large-scale configurations. It was found that the coordination numbers of Ge, Sb and S are around the values predicted by the Mott-rule (4, 3 and 2, respectively). The Ga atoms have on average 4 nearest neighbors. The structure of these stoichiometric glasses can be described by the chemically ordered network model: Ge-S, Ga-S and Sb-S bonds are the most important. A distortion of Ge(Ga)S$_{4/2}$ and/or SbS$_{3/2}$ units can be observed in the form of long Ge(Ga)-S and/or Sb-S distances (0.3 - 0.4 {\AA} higher than the usual covalent bond lengths).

[59]  arXiv:1806.08150 (cross-list from quant-ph) [pdf, other]
Title: The notion of locality in relational quantum mechanics
Comments: 6 pages, 2 figures
Subjects: Quantum Physics (quant-ph); History and Philosophy of Physics (physics.hist-ph)

The term 'locality' is used in different contexts with different meanings. There have been claims that relational quantum mechanics is local, but it is not clear then how it accounts for the effects that go under the usual name of quantum non-locality. The present article shows that the failure of 'locality' in the sense of Bell, once interpreted in the relational framework, reduces to the existence of a common cause in an indeterministic context. In particular, there is no need to appeal to a mysterious space-like influence to understand it.

[60]  arXiv:1806.08166 (cross-list from astro-ph.SR) [pdf, other]
Title: Testing Alfvén wave propagation in a realistic set-up of the solar atmosphere
Comments: 17 pages, 8 figures, 1 table and 3 animation links (submitted to the Geophysical and Astrophysical Fluid dynamics special issue- Algorithms and physics of the Pencil code)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Computational Physics (physics.comp-ph)

We present a radiative magneto-hydrodynamic simulation set-up using the Pencil code to study the generation, propagation and dissipation of Alfv\'en waves in the solar atmosphere which includes a convective layer and photosphere below, and the chromosphere, transition region and the corona above. We outline the procedure to prepare the initial state where the solar convection has reached a steady state and the imposed external magnetic field has reached the final value, gradually increasing from a very small initial value. Any new simulation to study Alfv\'en wave propagation can be started from this state which has been thus prepared. We present first results about the nature of waves excited in this simulation run.

[61]  arXiv:1806.08219 (cross-list from cond-mat.mtrl-sci) [pdf, ps, other]
Title: Growth evolution of self-affine thermally evaporated KBr thin films: A fractal assessment
Subjects: Materials Science (cond-mat.mtrl-sci); Instrumentation and Detectors (physics.ins-det)

In this article, fractal concepts were used to explore the thermally evaporated potassium bromide thin films of different thicknesses 200, 300, and 500 nm respectively; grown on aluminium substrates at room temperature. The self-affine or self similar nature of growing surfaces was investigated by autocorrelation function and obtained results are compared with the morphological envelope method. Theoretical estimations revealed that the global surface parameters such as, interface width and lateral correlation length are monotonically decreased with increasing film thickness. Also, from height profile and A-F plots, it has been perceived that irregularity/ complexity of growing layers was significantly influenced by thickness. On the other hand, the fractal dimension and local roughness exponent, estimated by height-height correlation function, do not suggest such dependency.

[62]  arXiv:1806.08332 (cross-list from cs.HC) [pdf]
Title: Towards Commodity, Web-Based Augmented Reality Applications for Research and Education in Chemistry and Structural Biology
Comments: 8 pages, 6 figures
Subjects: Human-Computer Interaction (cs.HC); Emerging Technologies (cs.ET); Multimedia (cs.MM); Biological Physics (physics.bio-ph); Biomolecules (q-bio.BM)

This article reports proof-of-concept web apps that use commodity open-source technologies for augmented and virtual reality to tackle real-world problems from chemistry and structural biology. The apps include demonstrations of molecular visualization at atomistic and coarse-grained levels, coarse-grained modeling of molecular physics, on-the-fly calculation of experimental observables and comparison to actual data, and simulated chemical reactivity. Along the results and in the discussion section, future perspectives are depicted based on recent works in the areas of machine learning for chemistry, transcompilation of programs into JavaScript, and advanced APIs and libraries supported by major web browsers. Together, the developments presented and discussed in this article will certainly lead to the next generation of tools for truly interactive molecular modeling that can streamline human thought and intent with the numerical processing power of computers.

Replacements for Fri, 22 Jun 18

[63]  arXiv:1606.06111 (replaced) [pdf, ps, other]
Title: Deviations from universality in the fluctuation behavior of a heterogeneous complex system reveal intrinsic properties of components: The case of the international currency market
Comments: 10 pages, 6 figures, final revised version
Subjects: Statistical Finance (q-fin.ST); Physics and Society (physics.soc-ph)
[64]  arXiv:1705.04472 (replaced) [pdf, other]
Title: Nonclassical light from large ensemble of trapped ions
Journal-ref: Phys. Rev. Lett. 120, 253602 (2018)
Subjects: Quantum Physics (quant-ph); Atomic Physics (physics.atom-ph)
[65]  arXiv:1707.04120 (replaced) [pdf, ps, other]
Title: Simulating polaron biophysics with Rydberg atoms
Journal-ref: Sci. Rep. 8, 9247 (2018)
Subjects: Atomic Physics (physics.atom-ph); Quantum Gases (cond-mat.quant-gas); Pattern Formation and Solitons (nlin.PS)
[66]  arXiv:1709.06615 (replaced) [pdf, other]
Title: Permutational symmetries for coincidence rates in multi-mode multi-photonic interferometry
Journal-ref: Phys. Rev. A 97, 063802 (2018)
Subjects: Quantum Physics (quant-ph); Optics (physics.optics)
[67]  arXiv:1710.05337 (replaced) [pdf, other]
Title: Observation of Laser Power Amplification in a Self-Injecting Laser Wakefield Accelerator
Comments: 6 pages, 4 figures. Published in PRL
Journal-ref: Physical Review Letters 120, 254801 (2018)
Subjects: Plasma Physics (physics.plasm-ph)
[68]  arXiv:1710.06833 (replaced) [pdf]
Title: Emission enhancement in dielectric nanocomposites
Journal-ref: D. Jalas, K. Marvin Schulz, A. Yu. Petrov, and M. Eich, "Emission enhancement in dielectric nanocomposites," Opt. Express 26, 16352-16364 (2018)
Subjects: Optics (physics.optics)
[69]  arXiv:1710.07629 (replaced) [pdf, other]
[70]  arXiv:1711.06904 (replaced) [pdf]
Title: A Study Concerning the Electronic Conductivity in Eumelanin Thin Films
Comments: 4 pages; 4 figure
Subjects: Applied Physics (physics.app-ph); Soft Condensed Matter (cond-mat.soft)
[71]  arXiv:1711.09132 (replaced) [pdf, other]
Title: Multiparameter Gaussian Quantum Metrology
Comments: 14 pages, 3 figures; expanded and updated; to appear in Physical Review A
Subjects: Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); Mathematical Physics (math-ph); Instrumentation and Detectors (physics.ins-det); Optics (physics.optics)
[72]  arXiv:1712.01561 (replaced) [pdf, other]
Title: A new measure for community structures through indirect social connections
Subjects: Social and Information Networks (cs.SI); Physics and Society (physics.soc-ph)
[73]  arXiv:1802.08029 (replaced) [pdf, other]
Title: Optical Chirality of Time-Harmonic Wavefields for Classification of Scatterers
Comments: 13 pages, 4 figures; updated references [v2]; changed title, published in Sci. Rep. [v3]
Journal-ref: Gutsche, P. & Nieto-Vesperinas, M. Optical Chirality of Time-Harmonic Wavefields for Classification of Scatterers. Sci. Rep. 8, 9416 (2018)
Subjects: Optics (physics.optics)
[74]  arXiv:1803.00461 (replaced) [pdf, other]
Title: Modeling the evolution and propagation of the 2017 September 9th and 10th CMEs and SEPs arriving at Mars constrained by remote-sensing and in-situ measurement
Subjects: Space Physics (physics.space-ph); Earth and Planetary Astrophysics (astro-ph.EP)
[75]  arXiv:1803.03942 (replaced) [pdf, other]
Title: Self-organized system-size oscillation of a stochastic lattice-gas model
Comments: added references; changed style of figures; added some more explanations; results unchanged
Subjects: Biological Physics (physics.bio-ph); Statistical Mechanics (cond-mat.stat-mech); Subcellular Processes (q-bio.SC)
[76]  arXiv:1803.04256 (replaced) [pdf, other]
Title: Evolving wormhole supported by dark matter and dark energy
Authors: Ali Övgün
Comments: 6 pages, two column
Subjects: General Physics (physics.gen-ph)
[77]  arXiv:1804.01780 (replaced) [pdf, other]
[78]  arXiv:1804.03479 (replaced) [pdf, other]
Title: Magnetohydrodynamics with GAMER
Comments: 29 pages, 22 figures, 1 table. GAMER-MHD will soon become available at this https URL
Journal-ref: The Astrophysical Journal supplement series, 236, 50, 2018
Subjects: Computational Physics (physics.comp-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM)
[79]  arXiv:1804.05987 (replaced) [pdf, other]
Title: Direct computation of the quantum partition function by path-integral nested sampling
Subjects: Quantum Physics (quant-ph); Chemical Physics (physics.chem-ph); Computational Physics (physics.comp-ph)
[80]  arXiv:1804.07488 (replaced) [pdf, other]
Title: Temporal Feedback Control of High-Intensity Laser Pulses to Optimize Ultrafast Heating of Atomic Clusters
Comments: 5 pages, 3 figures, Published in APL
Journal-ref: Appl. Phys. Lett. 112, 244101 (2018)
Subjects: Plasma Physics (physics.plasm-ph)
[81]  arXiv:1806.00415 (replaced) [pdf]
Title: A Numerical Study of the Relationship Between Erectile Pressure and Shear Wave Speed of Corpus Cavernosa in Ultrasound Vibro-elastography
Comments: 18 pages, 5 figures. 1 table
Subjects: Tissues and Organs (q-bio.TO); Signal Processing (eess.SP); Medical Physics (physics.med-ph)
[82]  arXiv:1806.00725 (replaced) [pdf, other]
Title: Integrated Tempering Enhanced Sampling Method as the Infinite Switching Limit of Simulated Tempering
Comments: 9 pages, 3 figures
Subjects: Numerical Analysis (math.NA); Chemical Physics (physics.chem-ph); Computational Physics (physics.comp-ph)
[83]  arXiv:1806.01989 (replaced) [pdf]
Title: Design of Voltage Pulse Control Module for Free Space Measurement-Device-Independent Quantum Key Distribution
Subjects: Signal Processing (eess.SP); Emerging Technologies (cs.ET); Applied Physics (physics.app-ph)
[84]  arXiv:1806.02334 (replaced) [pdf]
Title: A Gravitational Wave Transmitter
Comments: 19 pages
Subjects: Popular Physics (physics.pop-ph); General Relativity and Quantum Cosmology (gr-qc)
[85]  arXiv:1806.04082 (replaced) [pdf, other]
Title: Design a TDC in SiGe for RPC's electronics Front-end for the use in a high-rate experiment
Comments: 7 pages, 11 figures, RPC conference 2018, JINST 2018
Subjects: Instrumentation and Detectors (physics.ins-det)
[86]  arXiv:1806.05150 (replaced) [pdf, other]
Title: Phase-locking between different partial-waves in atom-ion spin-exchange collisions
Comments: 5 pages, 5 figures and Supplemental Material
Subjects: Atomic Physics (physics.atom-ph); Quantum Gases (cond-mat.quant-gas); Quantum Physics (quant-ph)
[87]  arXiv:1806.06138 (replaced) [pdf]
Title: Femtosecond laser inscription of nonlinear photonic circuits in Gallium Lanthanum Sulphide glass
Subjects: Optics (physics.optics)
[88]  arXiv:1806.07451 (replaced) [pdf]
Title: Average individuals tweet more often during extreme events: An ideal mechanism for social contagion
Subjects: Social and Information Networks (cs.SI); Physics and Society (physics.soc-ph)
[89]  arXiv:1806.07479 (replaced) [pdf, other]
Title: Weight Thresholding on Complex Networks
Subjects: Physics and Society (physics.soc-ph); Social and Information Networks (cs.SI)
[90]  arXiv:1806.07606 (replaced) [pdf, other]
Title: Toward theoretically limited SPP propagation length above two hundred microns on ultra-smooth silver surface
Subjects: Optics (physics.optics); Materials Science (cond-mat.mtrl-sci)
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