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- Mar 22 2018 q-fin.CP arXiv:1803.07904v1We introduce a model for the short-term dynamics of financial assets based on an application to finance of quantum gauge theory, developing ideas of Ilinski. We present a numerical algorithm for the computation of the probability distribution of prices and compare the results with APPLE stocks prices and the S&P500 index.
- Mar 22 2018 nucl-th arXiv:1803.07902v1We calculate the three- and four-particle correlations of identical pions in an evolving pion gas (EPG) model with Bose-Einstein condensation. The multi-pion correlation functions in the EPG model are analyzed in different momentum intervals and compared with the experimental data for Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. It is found that the multi-pion correlation functions and cumulant correlation functions are sensitive to the condensation fraction of the EPG sources in the low average transverse-momentum intervals of the three and four pions. The model results of the multi-pion correlations are consistent with the experimental data in a considerable degree, which gives a source condensation fraction between 16~--~47\%.
- Mar 22 2018 cs.SE arXiv:1803.07901v1Mutant selection refers to the problem of choosing, among a large number of mutants, the (few) ones to be used by the testers. We thus, investigate the problem of selecting the fault revealing mutants, i.e., the mutants that are most likely to lead to test cases that uncover unknown program faults. We formulate this problem as the fault revealing mutant selection and as the fault revealing mutant prioritization problems. We argue that these problems can be tackled through a set of 'static' program features. We thus, propose FaRM, a machine learning approach that learns to select fault revealing mutants. Experimental results involving 1,629 real faults show the practical benefits of our approach in both examined problems. Our results show that FaRM achieves a good trade-off between mutation testing application cost and effectiveness (measured in terms of faults revealed). We also show that FaRM outperforms random mutant sampling, which until now, is the most effective mutant selection method. In particular, our results show that with respect to mutant selection, our approach reveals 12% to 16% more faults than the random baselines, while, with respect to mutant prioritization, it achieves higher average percentage of revealed faults with a median difference of 10% (from the random mutant orderings).
- Mar 22 2018 cond-mat.supr-con cond-mat.mes-hall arXiv:1803.07900v1We investigate the properties of a weak link between two Rashba-based superconducting nanowires with geometric misalignment. By applying an external magnetic field the system can be driven into a topological non-trivial regime. We demonstrate that the Josephson current can be modulated in amplitude and sign through the variation of the applied field and, remarkably, via the angle controlling the spin-orbit locking mismatch at the interface of the nanowires. The proposed setup with misaligned coplanar nanowires provides the building block configuration for the manipulation of coherent transport via geometric-controlled mixing/splitting of interface states.
- Mar 22 2018 math.PR arXiv:1803.07899v1We discuss the asymptotic behaviour of random critical Boltzmann planar maps in which the degree of a typical face belongs to the domain of attraction of a stable law with index $\alpha \in (1,2]$. We prove that when conditioning such maps to have $n$ vertices, or $n$ edges, or $n$ faces, the vertex-set endowed with the graph distance suitably rescaled converges in distribution towards the celebrated Brownian map when $\alpha=2$, and, after extraction of a subsequence, towards another `$\alpha$-stable map' when $\alpha <2$, which improves on a first result due to Le Gall & Miermont who assumed slightly more regularity.
- Mar 22 2018 math.NA arXiv:1803.07898v1Explicit time stepping schemes are popular for linear acoustic and elastic wave propagation due to their simple nature which does not require sophisticated solvers for the inversion of the stiffness matrices. However, explicit schemes are only stable if the time step size is bounded by the mesh size in space subject to the so-called CFL condition. In micro-heterogeneous media, this condition is typically prohibitively restrictive because spatial oscillations of the medium need to be resolved by the discretization in space. This paper presents a way to reduce the spatial complexity in such a setting and, hence, to enable a relaxation of the CFL condition. This is done using the Localized Orthogonal Decomposition method as a tool for numerical homogenization. A complete convergence analysis is presented with appropriate, weak regularity assumptions on the initial data.
- The Hopf algebras associated by Gálvez-Carillo, Kock and Tonks to monoidal Möbius categories are shown to be distinct from those associated by Cibils and Rosso to Hopf quivers, except in the trivial case of a group algebra. Combinatorial left-sided Hopf algebras in the sense of Loday and Ronco do, however, provide examples, including planar rooted trees. As a new example, Milner's bigraphs also define a bialgebra in this way.
- Aritra Basu, S. A. Mao, Andrew Fletcher, Nissim Kanekar, Anvar Shukurov, Dominic Schnitzeler, Valentina Vacca, Henrik JunklewitzMar 22 2018 astro-ph.GA arXiv:1803.07896v1Deriving the Faraday rotation measure (RM) of quasar absorption line systems, which are tracers of high-redshift galaxies intervening background quasars, is a powerful tool for probing magnetic fields in distant galaxies. Statistically comparing the RM distributions of two quasar samples, with and without absorption line systems, allows one to infer magnetic field properties of the intervening galaxy population. Here, we have derived the analytical form of the probability distribution function (PDF) of RM produced by a single galaxy with an axisymmetric large-scale magnetic field. We then further determine the PDF of RM for one random sight line traversing each galaxy in a population with a large-scale magnetic field prescription. We find that the resulting PDF of RM is dominated by a Lorentzian with a width that is directly related to the mean axisymmetric large-scale field strength $\langle B_0 \rangle$ of the galaxy population if the dispersion of $B_0$ within the population is smaller than $\langle B_0 \rangle$. Provided that RMs produced by the intervening galaxies have been successfully isolated from other RM contributions along the line of sight, our simple model suggests that $\langle B_0 \rangle$ in galaxies probed by quasar absorption line systems can be measured within $\approx50$ per cent accuracy without additional constraints on the magneto-ionic medium properties of the galaxies. Finally, we discuss quasar sample selection criteria that are crucial to reliably interpret observations, and argue that within the limitations of the current database of absorption line systems, high-metallicity damped Lyman-$\alpha$ absorbers are best suited to study galactic dynamo action in distant disc galaxies.
- A novel algebraic method for finding invariant algebraic curves for a polynomial vector field in $\mathbb{C}^2$ is introduced. The structure of irreducible invariant algebraic curves for Liénard dynamical systems $x_t=y$, $y_t=-g(x)y-f(x)$ with $\text{deg} f=\text{deg} g+1$ is obtained. It is shown that there exist Liénard systems that possess more complicated invariant algebraic curves than it was supposed before. As an example, all irreducible invariant algebraic curves for the Liénard differential system with $\text{deg} f=3$, $\text{deg} g=2$ are obtained. All these results seem to be new.
- Jan Gospodaric, Artem Kuzmenko, Anna Pimenov, Christian Huber, Dieter Suess, Stefan Rotter, Andrei PimenovMar 22 2018 physics.optics arXiv:1803.07894v1The advancement of 3D-printing opens up a new way of constructing affordable custom terahertz (THz) components due to suitable printing resolution and THz transparency of polymer materials. We present a way of calculating, designing and fabricating a THz waveplate that phase-modulates an incident THz beam (\lambda=2.14 mm) in order to create a predefined intensity profile of the optical wavefront on a distant image plane. Our calculations were performed for two distinct target intensities with the use of a modified Gerchberg-Saxton algorithm. The resulting phase-modulating profiles were used to model the polyactide elements, which were printed out with a commercially available 3D-printer. The results were tested in an THz experimental setup equipped with a scanning option and they showed good agreement with theoretical predictions.
- Mar 22 2018 astro-ph.SR arXiv:1803.07893v1A novel time--frequency technique, called the synchrosqueezing transform (SST), is used to investigate the midterm periodic variations of magnetic fields on the solar surface. The Magnetic Plage Strength Index (MPSI) and the Mount Wilson Sunspot Index (MWSI), measured daily by the Mount Wilson Observatory between 1970 January 19 and 2012 January 22, are selected. The short-, mid, and longer-term periodicities are represented and decomposed by the SST with hardly any mode mixing. This demonstrates that the SST is a useful time--frequency analysis technique to characterize the periodic modes of helioseismic data. Apart from the fundamental modes of the annual periodicity, $\sim$27 day rotational cycle and $\sim$11 year solar cycle, the SST reveals several midterm periodicities in the two magnetic activity indices, specifically, $\sim$157 day (i.e., Rieger-type periodicity), and $\sim$1.3 and 1.7 years. The periodic modes, with 116.4 and 276.2 day periodicity in the MPSI, with 108.5 and 251.6 day periodicity in the MWSI, and the 157.7 day periodicity in the two indices, are in better accord with those significant periodicities derived from the Rossby waves theoretical model. This study suggests that the modes are caused by the Rossby waves. For the 1.30 and 1.71 year periodicity of the MPSI, and the 1.33 and 1.67 year periodicity of the MWSI, our analysis infers that they are related to those periodicity with the same timescale in the interior of the Sun and in the high atmospheric layers.
- Sohaib Younis, Claus Weiland, Robert Hoehndorf, Stefan Dressler, Thomas Hickler, Bernhard Seeger, Marco SchmidtMar 22 2018 q-bio.PE arXiv:1803.07892v1Herbaria worldwide are housing a treasure of 100s of millions of herbarium specimens, which are increasingly being digitized in recent years and thereby made more easily accessible to the scientific community. At the same time, deep learning algorithms are rapidly improving pattern recognition from images and these techniques are more and more being applied to biological objects. We are using digital images of herbarium specimens in order to identify taxa and traits of these collection objects by applying convolutional neural networks (CNN). Images of the 1000 species most frequently documented by herbarium specimens on GBIF have been downloaded and combined with morphological trait data, preprocessed and divided into training and test datasets for species and trait recognition. Good performance in both domains is promising to use this approach in future tools supporting taxonomy and natural history collection management.
- Muons have been accelerated by using a radio frequency accelerator for the first time. Negative muonium atoms (Mu$^-$), which are bound states of positive muons ($\mu^+$) and two electrons, are generated from $\mu^+$'s through the electron capture process in an aluminum degrader. The generated Mu$^-$'s are initially electrostatically accelerated and injected into a radio frequency quadrupole linac (RFQ). In the RFQ, the Mu$^-$'s are accelerated to 89 keV. The accelerated Mu$^-$'s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.
- Mar 22 2018 physics.class-ph arXiv:1803.07889v1The expression for the intensity of the electromagnetic field radiation is derived in the approximation next to the dipole one. The presented approach is based on fundamental equations from the introductory course on classical electrodynamics and straightforward mathematical transformations.
- Mar 22 2018 physics.soc-ph cond-mat.stat-mech arXiv:1803.07888v1We study the epidemic SIR model where each agent (susceptible, infected, or recovered) is able to move by performing a random walk with displacements $v$ and thus creating a different random geometric network at each iteration. Each susceptible agent can become infected with an infection rate $b$ and each infected agent becomes recovered with an immunization rate $c$, where $b+c=1$. We perform nonequilibrium Monte Carlo simulations in order to observe the effect of $v$ on the phase transition between the active and absorbing phases considering an interaction distance $\delta$, i.e., each agent interacts only with the neighbors that are at distance $\delta$ from it. We take into account the asynchronous updating scheme and compare our results with the standard SIR model. We found that for $v>0$ destroys the phase transition at $c=c_0$ and creates a line of phase transition points in the $v$ dependent $(c,\delta)$ space.
- We continue to investigate the properties of the earlier defined functions fm and gm, which depend on an initial arithmetic function f0. In this papers values of f0 are the Fine numbers. We investigate functions fi; gi; (i = 1; 2; 3; 4). For each function, we derive an explicit formula and give a combinatorial interpretation. It appears that g2 and g3 are well-known combinatoric object called the Catalan triangles. We finish with an identity consisting of ten items.
- Mar 22 2018 q-bio.MN arXiv:1803.07886v1The Turing patterning mechanism is believed to underly the formation of repetitive structures in development, such as zebrafish stripes and mammalian digits, but it has proved difficult to isolate the specific biochemical species responsible for pattern formation. Meanwhile, synthetic biologists have designed Turing systems for implementation in cell colonies, but none have yet led to visible patterns in the laboratory. In both cases, the relationship between underlying chemistry and emergent biology remains mysterious. To help resolve the mystery, this article asks the question: what kinds of biochemical systems can generate Turing patterns? We find general conditions for Turing pattern inception -- the ability to generate unstable patterns from random noise -- which may lead to the ultimate formation of stable patterns, depending on biochemical non-linearities. We find that a wide variety of systems can generate stable Turing patterns, including several which are currently unknown, such as two-species systems composed of two self-activators, and systems composed of a short-range inhibitor and a long-range activator. We furthermore find that systems which are widely believed to generate stable patterns may in fact only generate unstable patterns, which ultimately converge to spatially-homogeneous concentrations. Our results suggest that a much wider variety of systems than is commonly believed could be responsible for observed patterns in development, or could be good candidates for synthetic patterning networks.
- Mar 22 2018 math.PR arXiv:1803.07885v1In this note we consider stochastic heat equation with general additive Gaussian noise. Our aim is to derive some necessary and sufficient conditions on the Gaussian noise in order to solve the corresponding heat equation. We investigate this problem invoking two different methods, respectively based on variance computations and on path-wise considerations in Besov spaces. We are going to see that, as anticipated, both approaches lead to the same necessary and sufficient condition on the noise. In addition, the path-wise approach brings out regularity results for the solution.
- This article focuses on parabolic equations with rough diffusion coefficients which are ill-posed in the classical sense of distributions due to the presense of a singular forcing. Inspired by the philosophy of rough paths and regularity structures, we introduce a notion of modelled distribution which is suitable in this context. We prove two general tools for reconstruction and integration, as well as a product lemma which is tailor made for the reconstruction of the rough diffusion operator. This yields a partially automated deterministic theory, which we apply to obtain an existence and uniqueness theory for parabolic equations with rough diffusion coefficients and a singular forcing in the negative parabolic Hölder space of order larger than $-\frac{3}{2}$.
- Mar 22 2018 q-bio.NC arXiv:1803.07883v1Selfridge, along with Sutherland and Marr provided some of the earliest proposals for how to program computers to recognize shapes. Their emphasis on filtering for contour features, especially the orientation of boundary segments, was reinforced by the Nobel Prize winning work of Hubel & Wiesel who discovered that neurons in primary visual cortex selectively respond as a function of contour orientation. Countless investigators and theorists have continued to build on this approach. These models are often described as neuromorphic, which implies that the computational methods are based on biologically plausible principles. Recent work from the present lab has challenged the emphasis on orientation selectivity and the use of neural network principles. The goal of the present report is not to relitigate those issues, but to provide an alternative concept for encoding of shape information that may be useful to neuromorphic modelers.
- We study doubly stochastic operators with zero entropy. We generalize three famous theorems: the Rokhlin's theorem on genericity of zero entropy, the Kushnirenko's theorem on equivalence of discrete spectrum and nullity and the Halmos-von Neumann's theorem on representation of maps with discrete spectrum as group rotations.
- We unravel the correlated non-equilibrium dynamics of a mass balanced Bose-Fermi mixture in a one-dimensional optical lattice upon quenching an imposed harmonic trap from strong to weak confinement. Regarding the system's ground state, the competition between the inter and intraspecies interaction strength gives rise to the immiscible and miscible phases characterized by negligible and complete overlap of the constituting atomic clouds respectively. The resulting dynamical response depends strongly on the initial phase and consists of an expansion of each cloud and an interwell tunneling dynamics. For varying quench amplitude and referring to a fixed phase a multitude of response regimes is unveiled, being richer within the immiscible phase, which are described by distinct expansion strengths and tunneling channels. During the bosonic (fermionic) expansion the predominantly occupied wells show a correlated (anti-correlated) behavior and are incoherent as well as two-body anti-correlated among each other. Finally, the dependence of the response strength on the potential barrier height and the mass ratio of the components is discussed.
- Mar 22 2018 math.AC arXiv:1803.07880v1The Cohen-Macaulay property of a graph arising from a poset has been studied by various authors. In this article, we study the Cohen-Macaulay property of a graph arising from a family of reflexive and antisymmetric relations on a set. We use this result to find classes of multipartite graphs which are Cohen-Macaulay.
- A large fraction of the electronic health records consists of clinical measurements collected over time, such as blood tests, which provide important information about the health status of a patient. These sequences of clinical measurements are naturally represented as time series, characterized by multiple variables and the presence of missing data, which complicate analysis. In this work, we propose a surgical site infection detection framework for patients undergoing colorectal cancer surgery that is completely unsupervised, hence alleviating the problem of getting access to labelled training data. The framework is based on powerful kernels for multivariate time series that account for missing data when computing similarities. Our approach show superior performance compared to baselines that have to resort to imputation techniques and performs comparable to a supervised classification baseline.
- Mar 22 2018 physics.chem-ph arXiv:1803.07878v1We present and test an approximate method for the semiclassical calculation of vibrational spectra. The approach is based on the mixed time-averaging semiclassical initial value representation method, which is simplified to a form that contains a filter to remove contributions from approximately harmonic environmental degrees of freedom. This filter comes at no additional numerical cost, and it has no negative effect on the accuracy of peaks from the anharmonic system of interest. The method is successfully tested for a model Hamiltonian, and then applied to the study of the frequency shift of iodine in a krypton matrix. Using a hierarchic model with up to 108 normal modes included in the calculation, we show how the dynamical interaction between iodine and krypton yields results for the lowest excited iodine peaks that reproduce experimental findings to a high degree of accuracy.
- One of the key processes in Agriculture is quality measurement throughout the transportation of grains along its complex supply chain. This procedure is suitable for failures, such as delays to final destinations, poor monitoring, and frauds. To address the grain quality measurement challenge through the transportation chain, novel technologies, such as Distributed Ledger and Blockchain, can bring more efficiency and resilience to the process. Particularly, Blockchain is a new type of distributed database in which transactions are securely appended using cryptography and hashed pointers. Those transactions can be generated and ruled by special network-embedded software -- known as smart contracts -- that may be public to all nodes of the network or may be private to a specific set of peer nodes. This paper analyses the implementation of Blockchain technology targeting grain quality assurance tracking in a real scenario. Preliminary results support a potential demand for a Blockchain-based certification that would lead to an added valuation of around 15% for GM-free soy in the scope of a Grain Exporter Business Network in Brazil.
- Mar 22 2018 cond-mat.stat-mech arXiv:1803.07876v1The elastic backbone is the set of all shortest paths. We found a new phase transition at $p_{eb}$ above the classical percolation threshold at which the elastic backbone becomes dense. At this transition in $2d$ its fractal dimension is $1.750\pm 0.003$, and one obtains a novel set of critical exponents $\beta_{eb} = 0.50\pm 0.02$, $\gamma_{eb} = 1.97\pm 0.05$, and $\nu_{eb} = 2.00\pm 0.02$ fulfilling consistent critical scaling laws. Interestingly, however, the hyperscaling relation is violated. Using Binder's cumulant, we determine, with high precision, the critical probabilities $p_{eb}$ for the triangular and tilted square lattice for site and bond percolation. This transition describes a sudden rigidification as a function of density when stretching a damaged tissue.
- Observations of planets throughout our Solar System have revealed that the Earth is not alone in possessing natural, inter-annual atmospheric cycles. The equatorial middle atmospheres of the Earth, Jupiter and Saturn all exhibit a remarkably similar phenomenon - a vertical, cyclic pattern of alternating temperatures and zonal (east-west) wind regimes that propagate slowly downwards with a well-defined multi-Earth-year period. Earth's Quasi-Biennial Oscillation (QBO, observed in the lower stratospheres with an average period of 28 months) is one of the most regular, repeatable cycles exhibited by our climate system, and yet recent work has shown that this regularity can be disrupted by events occurring far away from the equatorial region, an example of a phenomenon known as atmospheric teleconnection. Here we reveal that Saturn's equatorial Quasi-Periodic Oscillation (QPO, with a ~15-year period) can also be dramatically perturbed. An intense springtime storm erupted at Saturn's northern mid-latitudes in December 2010, spawning a gigantic hot vortex in the stratosphere at $40^\circ$N that persisted for 3 years. Far from the storm, the Cassini temperature measurements showed a dramatic $\sim10$-K cooling in the 0.5-5 mbar range across the entire equatorial region, disrupting the regular QPO pattern and significantly altering the middle-atmospheric wind structure, suggesting an injection of westward momentum into the equatorial wind system from waves generated by the northern storm. Hence, as on Earth, meteorological activity at mid-latitudes can have a profound effect on the regular atmospheric cycles in the tropics, demonstrating that waves can provide horizontal teleconnections between the phenomena shaping the middle atmospheres of giant planets.
- Mobile relaying is emerged as a promising technique to assist wireless communication, driven by the rapid development of unmanned aerial vehicles (UAVs). In this paper, we study secure transmission in a four-node (source, destination, mobile relay, and eavesdropper) system, wherein we focus on maximizing the secrecy rate via jointly optimizing the relay trajectory and the source/relay transmit power. Nevertheless, due to the coupling of the trajectory designing and the power allocating, the secrecy rate maximization (SRM) problem is intractable to solve. Accordingly, we propose an alternating optimization (AO) approach, wherein the trajectory designing and the power allocating are tackled in an alternating manner. Unfortunately, the trajectory designing is a nonconvex problem, and thus is still hard to solve. To circumvent the nonconvexity, we exploit sequential convex programming (SCP) to derive an iterative algorithm, which is proven to converge to a Karush-Kuhn-Tucker (KKT) point of the trajectory design problem. The simulation results demonstrate the efficacy of the joint power and trajectory design in improving the secrecy throughput.
- Mar 22 2018 astro-ph.HE arXiv:1803.07873v1The collapsar model was proposed to explain the long-duration gamma-ray bursts (GRBs), while the short GRBs are associated with the mergers of compact objects. In the first case, mainly the energetics of the events is consistent with the proposed progenitor models, while the duration, time variability, as well as the afterglow emission may shed some light on the detailed properties of the collapsing massive stars. In the latter case, the recent discovery of the binary neutron star (NS-NS) merger in the gravitational wave observation made by LIGO (GW170817), and the detection of associated electromagnetic counterparts, for the first time gave a direct proof of the NS-NS merger being a progenitor of a short GRB. In general, all GRBs are believed to be powered by accretion through a rotationally supported torus, or by fast rotation of a compact object. For long ones, the rotation of the progenitor star is a key property in order to support accretion over relatively long activity periods, and also to sustain the rotation of the black hole itself. The latter is responsible for ejection of the relativistic jets, which are powered due to the extraction of the BH rotational energy, mitigated by the accretion torus and magnetic fields. The jets must break through the stellar envelope though, which poses a question on the efficiency of this process. Similar mechanisms of powering the jet ejection may act in short GRBs, which in this case may freely propagate through the interstellar medium. The power of the jets launched from the rotating black hole is at first associated mostly with the magnetic Poynting flux, and then at large distances it is transferred to the kinetic and finally radiative energy of the expanding shells.
- Mar 22 2018 astro-ph.HE arXiv:1803.07871v1External cosmic rays impinging upon circumstellar disks associated with young stellar objects provide an important source of ionization, and as such, play an important role in disk evolution and planet formation. However, these incoming cosmic rays are affected by a variety of physical processes internal to stellar/disk systems, including modulation by turbulent magnetic fields. Globally, these fields naturally provide both a funneling effect, where cosmic rays from larger volumes are focused into the disk region, and a magnetic mirroring effect, where cosmic rays are repelled due to the increasing field strength. This paper considers cosmic ray propagation in the presence of a turbulent spiral magnetic field, analogous to that produced by the Solar wind. The interaction of this wind with the interstellar medium defines a transition radius, analogous to the Heliopause, which provides the outer boundary to this problem. We construct a new coordinate system where one coordinate follows the spiral magnetic field lines and consider magnetic perturbations to the field in the perpendicular directions. The presence of magnetic turbulence replaces the mirroring points with a distribution of values and moves the mean location outward. Our results thus help quantify the degree to which cosmic ray fluxes are reduced in circumstellar disks by the presence of magnetic field structures that are shaped by stellar winds. The new coordinate system constructed herein should also be useful in other astronomical applications.
- Mar 22 2018 cs.NE arXiv:1803.07870v1Classification of multivariate time series (MTS) has been tackled with a large variety of methodologies and applied to a wide range of scenarios. Among the existing approaches, reservoir computing (RC) techniques, which implement a fixed and high-dimensional recurrent network to process sequential data, are computationally efficient tools to generate a vectorial, fixed-size representation of the MTS, which can be further processed by standard classifiers. Building upon previous works, in this paper we describe and compare several advanced RC-based approaches to generate unsupervised MTS representations, with a specific focus on their capability of yielding an accurate classification. Our main contribution is a new method to encode the MTS within the parameters of a linear model, trained to predict a low-dimensional embedding of the reservoir dynamics. We also study the combination of this representation technique when enhanced with a more complex bidirectional reservoir and non-linear readouts, such as deep neural networks with both fixed and flexible activation functions. We compare with state-of-the-art recurrent networks, standard RC approaches and time series kernels on multiple classification tasks, showing that the proposed algorithms can achieve superior classification accuracy, while being vastly more efficient to train.
- Mar 22 2018 cond-mat.other arXiv:1803.07869v1Supersaturated superfluid 3He-4He liquid mixture, separating into the 3He-concentrated c-phase and 3He-diluted d-phase, represents a unique possibility for studying macroscopic quantum nucleation and quantum phase-separation kinetics in binary mixtures at low temperatures down to absolute zero. One of possible heterogeneous mechanisms for the phase separation of supersaturated d-phase is associated with superfluidity of this phase and with a possible existence of quantized vortices playing a role of nucleation sites for the c-phase of liquid mixture. We analyze the growth dynamics of vortex core filled with the c-phase and determine the temperature behavior of c-phase nucleation rate and the crossover temperature between the classical and quantum nucleation mechanisms.
- A network model is considered where Poisson distributed base stations transmit to $N$ power-domain non-orthogonal multiple access (NOMA) users (UEs) each that employ successive interference cancellation (SIC) for decoding. We propose three models for the clustering of NOMA UEs and consider two different ordering techniques for the NOMA UEs: mean signal power-based and instantaneous signal-to-intercell-interference-and-noise-ratio-based. For each technique, we present a signal-to-interference-and-noise ratio analysis for the coverage of the typical UE. We plot the rate region for the two-user case and show that neither ordering technique is consistently superior to the other. We propose two efficient algorithms for finding a feasible resource allocation that maximize the cell sum rate $\mathcal{R}_{\rm tot}$, for general $N$, constrained to: 1) a minimum rate $\mathcal{T}$ for each UE, 2) identical rates for all UEs. We show the existence of: 1) an optimum $N$ that maximizes the constrained $\mathcal{R}_{\rm tot}$ given a set of network parameters, 2) a critical SIC level necessary for NOMA to outperform orthogonal multiple access. The results highlight the importance in choosing the network parameters $N$, the constraints, and the ordering technique to balance the $\mathcal{R}_{\rm tot}$ and fairness requirements. We also show that interference-aware UE clustering can significantly improve performance.
- Mar 22 2018 math.FA arXiv:1803.07865v1We study continuity properties on modulation spaces for $\tau$-pseudodifferential operators with symbols $a$ in Wiener amalgam spaces. We obtain boundedness results for $\tau \in (0,1)$ whereas, in the end-points $\tau=0$ and $\tau=1$, the corresponding operators are in general unbounded. Furthermore, for $\tau \in (0,1)$, we exhibit a function of $\tau$ which is an upper bound for the operator norm. The continuity properties of $\tau$-pseudodifferential operators, for any $\tau\in [0,1]$, with symbols $a$ in modulation spaces are well known. Here we find an upper bound for the operator norm which does not depend on the parameter $\tau \in [0,1]$, as expected. Key ingredients are uniform continuity estimates for $\tau$-Wigner distributions.
- Mar 22 2018 eess.SP arXiv:1803.07864v1Privacy-preserving smart meter control strategies proposed in the literature so far make some ideal assumptions such as instantaneous control without delay, lossless energy storage systems etc. In this paper, we present a one-step-ahead predictive control strategy using Bayesian risk to measure and control privacy leakage with an energy storage system. The controller estimates energy state using a three-circuit energy storage model to account for steady-state energy losses. With numerical experiments, the controller is evaluated with real household consumption data using a state-of-the-art adversarial algorithm. Results show that the state estimation of the energy storage system significantly affects the controller's performance. The results also show that the privacy leakage can be effectively reduced using an energy storage system but at the expense of energy loss.
- Mar 22 2018 cond-mat.supr-con arXiv:1803.07863v1We observed a novel voltage peak in the proximity effect induced superconducting gold (Au) nanowire while cooling the sample through the superconducting transition temperature. The voltage peak turned into dip in the warming process. The voltage peak (or dip) was found to be closely related to the emergence (vanishing) of the proximity induced superconductivity in the Au nanowire. The amplitude of the voltage signal depends on the temperature scanning rate and it cannot be detected when the temperature is changed slower than 0.03 K/min. This transient feature suggests the non-equilibrium property of the effect. The voltage peak could be understood by Ginzburg-Landau model as a combined result of the emergence of Cooper pairs with relatively lower free energy in W contact and the non-equilibrium diffusion of Cooper pairs and quasiparticles.
- Mar 22 2018 math.NA arXiv:1803.07861v1In this paper, we analyse the long-time behaviour of the extended RKN (ERKN) integrators when solving highly oscillatory Hamiltonian systems with a slowly varying, solution-dependent high frequency. It is proved that a symmetric ERKN integrator approximately conserves a modified action and a modified total energy over long time intervals by using the technique of varying-frequency modulated Fourier expansion developed in Numer. Math. 134 (2016) by Hairer and Lubich. An illustrative numerical experiment is carried out and the numerical results support the theoretical analysis presented in this paper. As a byproduct of this work, similar long-time behaviour is investigated for an RKN method.
- H. -R. Chen, K. -Y. Lin, P. -K. Chen, N. -C. Chiu, J. -B. Wang, C. -A. Chen, P. -P. Huang, S. -K. Yip, Yuki Kawaguchi, Y. -J. LinMar 22 2018 cond-mat.quant-gas arXiv:1803.07860v1We demonstrate coupling between the atomic spin and orbital-angular-momentum (OAM) of the atom's center-of-mass motion in a Bose-Einstein condensate (BEC). The coupling is induced by Raman-dressing lasers with a Laguerre-Gaussian beam, and creates coreless vortices in a $F=1$ $^{87}$Rb spinor BEC. We observe correlations between spin and OAM in the dressed state and characterize the spin texture; the result is in good agreement with the theory. In the presence of the Raman field our dressed state is stable for 0.1~s or longer, and it decays due to collision-induced relaxations. As we turn off the Raman beams, the vortex cores in the bare spin $|m_F=1\rangle$ and $|-1\rangle$ split. These spin-OAM coupled systems with the Raman-dressing approach have great potentials in exploring new topological textures and quantum states.
- Intrinsic stochasticity can induce highly non-trivial effects on dynamical systems, including stochastic and coherence resonance, noise induced bistability, noise-induced oscillations, to name but a few. In this paper we revisit a mechanism first investigated in the context of neuroscience by which relatively small demographic (intrinsic) fluctuations can lead to the emergence of avalanching behavior in systems that are deterministically characterized by a single stable fixed point (up state). The anomalously large response of such systems to stochasticity stems (or is strongly associated with) the existence of a "non-normal" stability matrix at the deterministic fixed point, which may induce the system to be "reactive". Here, we further investigate this mechanism by exploring the interplay between non-normality and intrinsic (demographic) stochasticity, by employing a number of analytical and computational approaches. We establish, in particular, that the resulting dynamics in this type of systems cannot be simply derived from a scalar potential but, additionally, one needs to consider a curl flux which describes the essential non-equilibrium nature of this type of noisy non-normal systems. Moreover, we shed further light on the origin of the phenomenon, introduce the novel concept of "non-linear reactivity", and rationalize of the observed the value of the emerging avalanche exponents.
- We use certain special prehomogeneous representations of algebraic groups in order to construct aCM vector bundles, possibly Ulrich, on certain families of hypersurfaces. Among other results, we show that a general cubic hypersurface of dimension seven admitsan indecomposable Ulrich bundle of rank nine, and that a general cubic fourfold admits an unsplit aCM bundle of rank six.
- Mar 22 2018 physics.hist-ph physics.pop-ph arXiv:1803.07855v1This essay demonstrates the key role of Astronomy in the Botticelli's Venus and Mars-NG915 painting, to date only very partially understood. Worthwhile coincidences among the principles of the Ficinian philosophy, the historical characters involved and the compositional elements of the painting, show how the astronomical knowledge of that time strongly influenced this masterpiece. First, Astronomy provides its precise dating since Botticelli used the astronomical ephemerides of his time, albeit preserving a mythological meaning, and a clue for his signature. Second, it allows the correlation among the Botticelli's creative intention, the historical facts and the astronomical phenomena such as the heliacal rising of planet Venus in conjunction with the Aquarius constellation dating back to the earliest representations of Venus in Mesopotamian culture. This work not only bears a significant value for the history of science and art, but, in the current era of three-dimensional mapping of billion stars about to be delivered by Gaia, states the role of astronomical heritage in Western culture. Finally, following the same method, a precise astronomical dating for the famous Primavera painting is suggested.
- Mar 22 2018 cond-mat.mtrl-sci arXiv:1803.07854v1Boltzmann transport calculations based on band structures generated with density functional theory (DFT) are often used in the discovery and analysis of thermoelectric materials. In standard implementations, such calculations require dense ${\it k}$-point sampling of the Brillouin zone and are therefore typically limited to the generalized gradient approximation (GGA), whereas more accurate methods such as hybrid functionals would have been preferable. GGA variants, however, generally underestimate the band gap. While premature onset of minority carriers can be avoided with scissor corrections, the band gap also affects the band curvature. In this study, we resolved the ${\it k}$-point sampling issue in hybrid-functional based calculations by extending our recently developed ${\it k}\cdot\tilde{{\it p}}$ interpolation scheme [Comput. Mater. Sci. 134, 17 (2017)] to non-local one-electron potentials and spin-orbit coupling. The Seebeck coefficient generated based on hybrid functionals were found to agree better than GGA with experimental data for GaAs, InP, and PbTe. For PbTe, even the choice of hybrid functional has bearing on the interpretation of experimental data, which we attribute to the description of valley convergence of the valence band.
- Mar 22 2018 math.GR arXiv:1803.07853v1It is proved in [J. Group Theory, \bf 10 (2007), 859-866] that if $G$ is a finite $p$-group such that $(G,Z(G))$ is a Camina pair, then $|G|$ divides $|\Aut(G)|$. We give a very short and elementary proof of this result.
- Mar 22 2018 math.AP arXiv:1803.07852v1In this note, we establish sharp regularity for solutions to the following generalized $p$- Poisson equation $$-\ div\ \big(\langle A∇u,∇u\rangle^\fracp-22A∇u\big)=-\ div\ \mathbfh+f.$$ in the plane (i.e. in $\mathbb{R}^n=\mathbb{R}^2$) for $p>2$ in the presence of Dirichlet as well as Neumann boundary conditions and with $\mathbf{h}\in C^{1-n/q}$, $f\in L^q$, $2=n<q\leq\infty$. The regularity assumptions on the principal part $A$ as well as that on the Dirichlet/Neumann conditions are exactly the same as in the linear case and therefore sharp (see Remark 2.5 below). Our main results Theorem 2.3 and Theorem 2.4 should be thought of as the boundary analogues of the sharp interior regularity result established in the recent interesting paper [1] in the case of \beginequation\labele0 -\ div\ (|∇u|^p-2 ∇u) =f \endequation for more general variable coefficient operators and with an additional divergence term.
- G. P. Smith, C. P. L. Berry, M. Bianconi, W. M. Farr, M. Jauzac, R. J. Massey, J. Richard, A. Robertson, K. Sharon, A. Vecchio, J. VeitchMar 22 2018 astro-ph.CO gr-qc arXiv:1803.07851v1Discovery of strongly-lensed gravitational wave (GW) sources will unveil binary compact objects at higher redshifts and lower intrinsic luminosities than is possible without lensing. Such systems will yield unprecedented constraints on the mass distribution in galaxy clusters, measurements of the polarization of GWs, tests of General Relativity, and constraints on the Hubble parameter. Excited by these prospects, and intrigued by the presence of so-called "heavy black holes" in the early detections by LIGO-Virgo, we commenced a search for strongly-lensed GWs and possible electromagnetic counterparts in the latter stages of the second LIGO observing run (O2). Here, we summarise our calculation of the detection rate of strongly-lensed GWs, describe our review of BBH detections from O1, outline our observing strategy in O2, summarize our follow-up observations of GW170814, and discuss the future prospects of detection.
- Mar 22 2018 q-bio.QM arXiv:1803.07850v1Identification of patients at high risk for readmission could help reduce morbidity and mortality as well as healthcare costs. Most of the existing studies on readmission prediction did not compare the contribution of data categories. In this study we analyzed relative contribution of 90,101 variables across 398,884 admission records corresponding to 163,468 patients, including patient demographics, historical hospitalization information, discharge disposition, diagnoses, procedures, medications and laboratory test results. We established an interpretable readmission prediction model based on Logistic Regression in scikit-learn, and added the available variables to the model one by one in order to analyze the influences of individual data categories on readmission prediction accuracy. Diagnosis related groups (c-statistic increment of 0.0933) and discharge disposition (c-statistic increment of 0.0269) were the strongest contributors to model accuracy. Additionally, we also identified the top ten contributing variables in every data category.
- Menglei Zhou, Zheng Cao, Askar Abdikamalov, Dimitry Ayzenberg, Cosimo Bambi, Leonardo Modesto, Sourabh NampalliwarMar 22 2018 gr-qc astro-ph.HE arXiv:1803.07849v1Recently, two of us have found a family of singularity-free rotating black hole solutions in Einstein's conformal gravity. These spacetimes are characterized by three parameters: the black hole mass $M$, the black hole spin angular momentum $J$, and a parameter $L$ that is not specified by the theory but can be expected to be proportional to the black hole mass $M$. The Kerr black hole solution of Einstein's gravity is recovered for $L = 0$. In a previous paper, we showed that X-ray data of astrophysical black holes require $L/M < 1.2$. In the present paper, we report the results of a more sophisticated analysis. We apply the X-ray reflection model \sc relxill\_nk to \textslNuSTAR and \textslSwift data of the supermassive black hole in 1H0707-495. We find the constraint $L/M < 0.45$ (90% confidence level).
- We investigate the nonperturbative degrees of freedom of a class of weakly nonlocal gravitational theories that have been proposed as an ultraviolet completion of general relativity. At the perturbative level, it is known that the degrees of freedom of nonlocal gravity are the same of the Einstein--Hilbert theory around any maximally symmetric spacetime. We prove that, at the nonperturbative level, the degrees of freedom are actually eight in four dimensions, contrary to what one might guess on the basis of the "infinite number of derivatives" present in the action. Six of these degrees of freedom may play a role at large scales and on curved backgrounds. We also propose a criterion to select the form factor almost uniquely.
- Mar 22 2018 physics.ins-det physics.atom-ph arXiv:1803.07846v1We report on a 2x2 array of radio-frequency atomic magnetometers in magnetic induction tomography configuration. Active detection, localization, and real-time tracking of conductive, non-magnetic targets are demonstrated in air and saline water. Penetration in different media and detection are achieved thanks to the sensitivity and tunability of the sensors, and to the active nature of magnetic induction probing. We obtained a 100% success rate for automatic detection and 93% success rate for automatic localization in air and water, up to 190 mm away from the sensors' plane (100 mm underwater). We anticipate magnetic induction tomography with arrays of atomic magnetometers finding applications in civil engineering and maintenance, oil&gas industry, geological surveys, marine science, archeology, search and rescue, and security and surveillance.

Using Automatic Refactoring to Improve Energy Efficiency of Android Apps

Luis Cruz Mar 16 2018 15:34 UTCDan Elton Mar 16 2018 04:36 UTC

Comments are appreciated. Message me here or on twitter @moreisdifferent

Code is open source and available at :

[https://github.com/delton137/PIMD-F90][1][1]: https://github.com/delton137/PIMD-F90

Danial Dervovic Mar 01 2018 12:08 UTC

...(continued)Hello again Māris, many thanks for your patience. Your comments and questions have given me much food for thought, and scope for an amended version of the paper -- please see my responses below.

Please if any of the authors of [AST17 [arXiv:1712.01609](https://arxiv.org/abs/1712.01609)] have any fu

igorot Feb 28 2018 05:19 UTC

The Igorots built an [online community][1] that helps in the exchange, revitalization, practice, and learning of indigenous culture. It is the first and only Igorot community on the web.

[1]: https://www.igorotage.com/

Beni Yoshida Feb 13 2018 19:53 UTC

...(continued)This is not a direct answer to your question, but may give some intuition to formulate the problem in a more precise language. (And I simplify the discussion drastically). Consider a static slice of an empty AdS space (just a hyperbolic space) and imagine an operator which creates a particle at some

Abhinav Deshpande Feb 10 2018 15:42 UTC

...(continued)I see. Yes, the epsilon ball issue seems to be a thorny one in the prevalent definition, since the gate complexity to reach a target state from any of a fixed set of initial states depends on epsilon, and not in a very nice way (I imagine that it's all riddled with discontinuities). It would be inte

Elizabeth Crosson Feb 10 2018 05:49 UTC

...(continued)Thanks for the correction Abhinav, indeed I meant that the complexity of |psi(t)> grows linearly with t.

Producing an arbitrary state |phi> exactly is also too demanding for the circuit model, by the well-known argument that given any finite set of gates, the set of states that can be reached i

Abhinav Deshpande Feb 09 2018 20:21 UTC

...(continued)Elizabeth, interesting comment! Did you mean to say that the complexity of $U(t)$ increases linearly with $t$ as opposed to exponentially?

Also, I'm confused about your definition. First, let us assume that the initial state is well defined and is $|\psi(0)\rangle $.

If you define the complexit

Elizabeth Crosson Feb 08 2018 04:27 UTC

...(continued)The complexity of a state depends on the dynamics that one is allowed to use to generate the state. If we restrict the dynamics to be "evolving according a specific Hamiltonian H" then we immediately have that the complexity of U(t) = exp(i H t) grows exponentially with t, up until recurrences that

Danial Dervovic Feb 05 2018 15:03 UTC

...(continued)Thank you Māris for the extremely well thought-out and articulated points here.

I think this very clearly highlights the need to think explicitly about the precompute time if using the lifting to directly simulate the quantum walk, amongst other things.

I wish to give a well-considered respons

- Supported by Silverpond.