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arxiv_dataset-32001202.1326 | A New Model of Chemical Bonding in Ionic Melts
cond-mat.mtrl-sci physics.chem-ph
We developed a new physical model to predict macroscopic properties of
inorganic molten systems using a realistic description of inter-atomic
interactions. Unlike the conventional approach, which tends to overestimate
viscosity by several times, our systems consist of a set of ions with an
admixture of neutral atoms. The neutral atom subsystem is a consequence of the
covalent/ionic state reduction, occurring in the liquid phase. Comparison of
the calculated macroscopic properties (shear viscosity and self-diffusion
constants) with the experiment demonstrates good performance of our model. The
presented approach is inspired by a significant degree of covalent interaction
between the alkali and chlorine atoms, predicted by the coupled cluster theory.
| arxiv topic:cond-mat.mtrl-sci physics.chem-ph |
arxiv_dataset-32011202.1426 | Approximate Bayesian Computation for Astronomical Model Analysis: A Case
Study in Galaxy Demographics and Morphological Transformation at High
Redshift
astro-ph.IM astro-ph.CO
"Approximate Bayesian Computation" (ABC) represents a powerful methodology
for the analysis of complex stochastic systems for which the likelihood of the
observed data under an arbitrary set of input parameters may be entirely
intractable-the latter condition rendering useless the standard machinery of
tractable likelihood-based, Bayesian statistical inference (e.g. conventional
Markov Chain Monte Carlo simulation; MCMC). In this article we demonstrate the
potential of ABC for astronomical model analysis by application to a case study
in the morphological transformation of high redshift galaxies. To this end we
develop, first, a stochastic model for the competing processes of merging and
secular evolution in the early Universe; and second, through an ABC-based
comparison against the observed demographics of massive (M_gal > 10^11 M_sun)
galaxies (at 1.5 < z < 3) in the CANDELS/EGS dataset we derive posterior
probability densities for the key parameters of this model. The "Sequential
Monte Carlo" (SMC) implementation of ABC exhibited herein, featuring both a
self-generating target sequence and self-refining MCMC kernel, is amongst the
most efficient of contemporary approaches to this important statistical
algorithm. We highlight as well through our chosen case study the value of
careful summary statistic selection, and demonstrate two modern strategies for
assessment and optimisation in this regard. Ultimately, our ABC analysis of the
high redshift morphological mix returns tight constraints on the evolving
merger rate in the early Universe and favours major merging (with disc survival
or rapid reformation) over secular evolution as the mechanism most responsible
for building up the first generation of bulges in early-type disks.
| arxiv topic:astro-ph.IM astro-ph.CO |
arxiv_dataset-32021202.1526 | Quantum phases of disordered flatband lattice fractional quantum Hall
systems
cond-mat.str-el
By numerical exact diagonalization techniques, we obtain the quantum phase
diagram of the lattice fractional quantum Hall (FQH) systems in the presence of
quenched disorder. By implementing an array of local potential traps
representing the disorder, we show that the system undergoes a series of
quantum phase transitions as the disorder and/or the interaction is tuned. As
the strength of potential traps is increased, the FQH state turns into a
compressible liquid, and then into a topologically trivial insulator. We use
numerically calculated energy gap, quantum degeneracy, Chern number,
entanglement spectrum, and fidelity to identify various quantum phases. The
connection to continuum FQH effects is also discussed.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-32031202.1626 | Phase Separation with Anisotropic Coherency Strain
cond-mat.mtrl-sci physics.chem-ph
We consider the effects of anisotropic coherency strain (due to lattice
mismatch) on phase separation in intercalation materials, motivated by the
high-rate Li-ion battery material \fepo. Using a phase-field model coupled to
elastic stresses, we analyze spinodal decomposition (linear instability of the
homogeneous state) as well as nonlinear evolution of the phase pattern at
constant mean filling. We consider fully anisotropic coherency strain and focus
on the novel case of simultaneous expansion and contraction along different
crystal axis, as in the case of \fepo, which leads to tilted, striped phase
boundaries in equilibrium.
| arxiv topic:cond-mat.mtrl-sci physics.chem-ph |
arxiv_dataset-32041202.1726 | Magneto-transport in a quantum network: Evidence of a mesoscopic switch
cond-mat.mes-hall
We investigate magneto-transport properties of a $\theta$ shaped three-arm
mesoscopic ring where the upper and lower sub-rings are threaded by
Aharonov-Bohm fluxes $\phi_1$ and $\phi_2$, respectively, within a
non-interacting electron picture. A discrete lattice model is used to describe
the quantum network in which two outer arms are subjected to binary alloy
lattices while the middle arm contains identical atomic sites. It is observed
that the presence of the middle arm provides localized states within the band
of extended regions and lead to the possibility of switching action from a high
conducting state to a low conducting one and vice versa. This behavior is
justified by studying persistent current in the network. Both the total current
and individual currents in three separate branches are computed by using
second-quantized formalism and our idea can be utilized to study magnetic
response in any complicated quantum network. The nature of localized
eigenstates are also investigated from probability amplitudes at different
sites of the quantum device.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-32051202.1826 | The KELT-South Telescope
astro-ph.IM astro-ph.EP
The Kilodegree Extremely Little Telescope (KELT) project is a survey for new
transiting planets around bright stars. KELT-South is a small-aperture,
wide-field automated telescope located at Sutherland, South Africa. The
telescope surveys a set of 26 degree by 26 degree fields around the southern
sky, and targets stars in the range of 8 < V < 10 mag, searching for transits
by Hot Jupiters. This paper describes the KELT-South system hardware and
software and discusses the quality of the observations. We show that KELT-South
is able to achieve the necessary photometric precision to detect transits of
Hot Jupiters around solar-type main-sequence stars.
| arxiv topic:astro-ph.IM astro-ph.EP |
arxiv_dataset-32061202.1926 | The formation of the Halpha line in the solar chromosphere
astro-ph.SR
We use state-of-the-art radiation-MHD simulations and 3D non-LTE radiative
transfer computations to investigate \Halpha\ line formation in the solar
chromosphere and apply the results of this investigation to develop the
potential of \Halpha\ as diagnostic of the chromosphere.
We show that one can accurately model \Halpha\ line formation assuming
statistical equilibrium and complete frequency redistribution provided the
computation of the model atmosphere included non-equilibrium ionization of
hydrogen, and the Lyman-$\alpha$ and Lyman-$\beta$ line profiles are described
by Doppler profiles.
We find that 3D radiative transfer is essential in modeling hydrogen lines
due to the low photon destruction probability in \Halpha. The \Halpha\ opacity
in the upper chromosphere is mainly sensitive to the mass density and only
weakly sensitive to temperature.
We find that the \Halpha\ line-core intensity is correlated with the average
formation height: the larger the average formation height, the lower the
intensity. The line-core width is a measure of the gas temperature in the
line-forming region. The fibril-like dark structures seen in \Halpha\ line-core
images computed from our model atmosphere are tracing magnetic field lines.
These structures are caused by field-aligned ridges of enhanced chromospheric
mass density that raise their average formation height, and therefore makes
them appear dark against their deeper-formed surroundings. We compare with
observations, and find that the simulated line-core widths are very similar to
the observed ones, without the need for additional microturbulence.
| arxiv topic:astro-ph.SR |
arxiv_dataset-32071202.2026 | A quantum genetic algorithm with quantum crossover and mutation
operations
cs.NE quant-ph
In the context of evolutionary quantum computing in the literal meaning, a
quantum crossover operation has not been introduced so far. Here, we introduce
a novel quantum genetic algorithm which has a quantum crossover procedure
performing crossovers among all chromosomes in parallel for each generation. A
complexity analysis shows that a quadratic speedup is achieved over its
classical counterpart in the dominant factor of the run time to handle each
generation.
| arxiv topic:cs.NE quant-ph |
arxiv_dataset-32081202.2126 | Discovery of Main-Belt Comet P/2006 VW139 by Pan-STARRS1
astro-ph.EP
Main belt asteroid (300163) 2006 VW139 (later designated P/2006 VW139) was
discovered to exhibit comet-like activity by the Pan-STARRS1 survey telescope
using automated point-spread-function analyses performed by PS1's Moving Object
Processing System. Deep follow-up observations show both a short (\sim 10")
antisolar dust tail and a longer (\sim 60") dust trail aligned with the
object's orbit plane, similar to the morphology observed for another main-belt
comet, P/2010 R2 (La Sagra), and other well-established comets, implying the
action of a long-lived, sublimation-driven emission event. Photometry showing
the brightness of the near-nucleus coma remaining constant over \sim 30 days
provides further evidence for this object's cometary nature, suggesting it is
in fact a main-belt comet, and not a disrupted asteroid. A spectroscopic search
for CN emission was unsuccessful, though we find an upper limit CN production
rate of Q_CN < 1.3x10^24 mol/s, from which we infer a water production rate of
Q_H2O < 10^26 mol/s. We also find an approximately linear optical spectral
slope of 7.2%/1000A, similar to other cometary dust comae. Numerical
simulations indicate that P/2006 VW139 is dynamically stable for > 100 Myr,
while a search for a potential asteroid family around the object reveals a
cluster of 24 asteroids within a cutoff distance of 68 m/s. At 70 m/s, this
cluster merges with the Themis family, suggesting that it could be similar to
the Beagle family to which another main-belt comet, 133P/Elst-Pizarro, belongs.
| arxiv topic:astro-ph.EP |
arxiv_dataset-32091202.2226 | The Cauchy Singular Integral Operator on Weighted Variable Lebesgue
Spaces
math.FA math.CA
Let $p:\R\to(1,\infty)$ be a globally log-H\"older continuous variable
exponent and $w:\R\to[0,\infty]$ be a weight. We prove that the Cauchy singular
integral operator $S$ is bounded on the weighted variable Lebesgue space
$L^{p(\cdot)}(\R,w)=\{f:fw\in L^{p(\cdot)}(\R)\}$ if and only if the weight $w$
satisfies \[ \sup_{-\infty<a<b<\infty}
\frac{1}{b-a}\|w\chi_{(a,b)}\|_{p(\cdot)}\|w^{-1}\chi_{(a,b)}\|_{p'(\cdot)}<\infty
\quad (1/p(x)+1/p'(x)=1). \]
| arxiv topic:math.FA math.CA |
arxiv_dataset-32101202.2326 | Qutrit Magic State Distillation
quant-ph
Magic state distillation (MSD) is a purification protocol that plays a
central role in fault tolerant quantum computation. Repeated iteration of the
steps of a MSD protocol, generates pure single non-stabilizer states, or magic
states, from multiple copies of a mixed resource state using stabilizer
operations only. Thus mixed resource states promote the stabilizer operations
to full universality. Magic state distillation was introduced for qubit-based
quantum computation, but little has been known concerning MSD in higher
dimensional qudit-based computation. Here, we describe a general approach for
studying MSD in higher dimensions. We use it to investigate the features of a
qutrit MSD protocol based on the 5-qutrit stabilizer code. We show that this
protocol distills non-stabilizer magic states, and identify two types of
states, that are attractors of this iteration map. Finally, we show how these
states may be converted, via stabilizer circuits alone, into a state suitable
for state injected implementation of a non-Clifford phase gate, enabling
non-Clifford unitary computation.
| arxiv topic:quant-ph |
arxiv_dataset-32111202.2426 | Massive particles and unitarity cuts
hep-ph
We present an extension of the spinor integration formalism of one loop
amplitudes from the double-cut to the single-cut case. This technique can be
applied for the computation of the tadpole coefficients. Moreover we describe
an off-shell continuation of one loop amplitudes that allows a finite
evaluation of the unitarity cuts in the channel of a single massive external
fermion.
| arxiv topic:hep-ph |
arxiv_dataset-32121202.2526 | Micro-canonical thermodynamics: Why does heat flow from hot to cold
cond-mat.stat-mech math.DS nlin.CD
We show how to use a central limit approximation for additive co-cycles to
describe non-equilibrium and far from equilibrium thermodynamic behavior. We
consider first two weakly coupled Hamiltonian dynamical systems initially at
different micro-canonical temperatures. We describe a stochastic model where
the energy-transfer between the two systems is considered as a random variable
satisfying a central limit approximation. We show that fluctuations in energy
observables are linearly related to the heat-transfer (dissipation). As a
result, on average, heat flows from hot to cold. We also consider the far from
equilibrium situation of a non-Hamiltonian thermostatted system as in Evans et
al. {\em Phys.\ Rev.\ Lett.} {\bf 71}, 2401 (1993). Applying the same central
limit approximation we re-derive their relation for the violation of the 2nd
law of thermodynamics. We note that time-reversal symmetry is not used in our
derivation.
| arxiv topic:cond-mat.stat-mech math.DS nlin.CD |
arxiv_dataset-32131202.2626 | Development of a high-sensitivity torsion balance to investigate the
thermal Casimir force
quant-ph cond-mat.mtrl-sci
We report development of a high-sensitivity torsion balance to measure the
thermal Casimir force. Special emphasis is placed on experimental
investigations of a possible surface electric force originating from surface
patch potentials that have been recently noticed by several experimental
groups. By gaining a proper understanding of the actual contribution of the
surface electric force in real materials, we aim to undertake precision force
measurements to resolve the Casimir force at finite temperature in real metals,
as well as in other semiconducting materials, such as graphene.
| arxiv topic:quant-ph cond-mat.mtrl-sci |
arxiv_dataset-32141202.2726 | An apparatus for immersing trapped ions into an ultracold gas of neutral
atoms
physics.atom-ph cond-mat.quant-gas quant-ph
We describe a hybrid vacuum system in which a single ion or a well defined
small number of trapped ions (in our case Ba$^+$ or Rb$^+$) can be immersed
into a cloud of ultracold neutral atoms (in our case Rb). This apparatus allows
for the study of collisions and interactions between atoms and ions in the
ultracold regime. Our setup is a combination of a Bose-Einstein condensation
(BEC) apparatus and a linear Paul trap. The main design feature of the
apparatus is to first separate the production locations for the ion and the
ultracold atoms and then to bring the two species together. This scheme has
advantages in terms of stability and available access to the region where the
atom-ion collision experiments are carried out. The ion and the atoms are
brought together using a moving 1-dimensional optical lattice transport which
vertically lifts the atomic sample over a distance of 30$\,$cm from its
production chamber into the center of the Paul trap in another chamber. We
present techniques to detect and control the relative position between the ion
and the atom cloud.
| arxiv topic:physics.atom-ph cond-mat.quant-gas quant-ph |
arxiv_dataset-32151202.2826 | Error Floor Approximation for LDPC Codes in the AWGN Channel
cs.IT math.IT
This paper addresses the prediction of error floors of low-density
parity-check (LDPC) codes with variable nodes of constant degree in the
additive white Gaussian noise (AWGN) channel. Specifically, we focus on the
performance of the sum-product algorithm (SPA) decoder formulated in the
log-likelihood ratio (LLR) domain. We hypothesize that several published error
floor levels are due to the manner in which decoder implementations handled the
LLRs at high SNRs. We employ an LLR-domain SPA decoder that does not saturate
near-certain messages and find the error rates of our decoder to be lower by at
least several orders of magnitude. We study the behavior of trapping sets (or
near-codewords) that are the dominant cause of the reported error floors.
We develop a refined linear model, based on the work of Sun and others, that
accurately predicts error floors caused by elementary tapping sets for
saturating decoders. Performance results of several codes at several levels of
decoder saturation are presented.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-32161202.2926 | Detection of Calendar-Based Periodicities of Interval-Based Temporal
Patterns
cs.DB
We present a novel technique to identify calendar-based (annual, monthly and
daily) periodicities of an interval-based temporal pattern. An interval-based
temporal pattern is a pattern that occurs across a time-interval, then
disappears for some time, again recurs across another time-interval and so on
and so forth. Given the sequence of time-intervals in which an interval-based
temporal pattern has occurred, we propose a method for identifying the extent
to which the pattern is periodic with respect to a calendar cycle. In
comparison to previous work, our method is asymptotically faster. We also show
an interesting relationship between periodicities across different levels of
any hierarchical timestamp (year/month/day, hour/minute/second etc.).
| arxiv topic:cs.DB |
arxiv_dataset-32171202.3026 | Updated study of the $\eta_c$ and $\eta_c^\prime$ decays into light
vector mesons
hep-ph hep-ex nucl-th
We re-investigate the exclusive decays of $\eta_c$ and $\eta_c^\prime$ to a
pair of light vector mesons, i.e. $\eta_c (\eta_c')\to VV$. The long-distance
intermediate meson loop (IML) effects are evaluated as a non-perturbative
mechanism in addition to the short-distance $c\bar{c}$ annihilation
contributions. We show that both processes can be reasonably well constrained
with the help of the available experimental data. Since $\eta_c$ and $\eta_c'$
are the spin-0 partners of $J/\psi$ and $\psi'$, respectively, our study is
useful for gaining insights into the pQCD helicity selection rule violations in
charmonium decays and the long-standing "$\rho\pi$ puzzle".
| arxiv topic:hep-ph hep-ex nucl-th |
arxiv_dataset-32181202.3126 | Sheaf Structures On a Class of Noncommutative Spectra
math.RA
We introduce a class of noncommutative spectra and give the sheaf structure
on the class of noncommutative spectra.
| arxiv topic:math.RA |
arxiv_dataset-32191202.3226 | Simultaneous B'V'R' Monitoring of BL Lacertae Object S5~0716+714 and
Detection of Inter-Band Time Delay
astro-ph.HE
We present the results of our optical monitoring of the BL Lac object S5
0716+714 on seven nights in 2006 December. The monitoring was carried out
simultaneously at three optical wavelengths with a novel photometric system.
The object did not show large-amplitude internight variations during this
period. Intranight variations were observed on four nights and probably on one
more. Strong bluer-when-brighter chromatism was detected on both intranight and
internight timescales. The intranight variation amplitude decreases in the
wavelength sequence of B', R', and V'. Cross correlation analyses revealed that
the variability at the $B'$ and $V'$ bands lead that at the $R'$ band by about
30 minutes on one night.
| arxiv topic:astro-ph.HE |
arxiv_dataset-32201202.3326 | Duality relations in a two-path interferometer with an asymmetric beam
splitter
quant-ph
We investigate quantitatively the wave-particle duality in a general
Mach-Zehnder interferometer setup with an asymmetric beam splitter. The
asymmetric beam splitter introduces additional a priori which-path knowledge,
which is different for a particle detected at one output port of the
interferometer and a particle detected at the other. Accordingly, the fringe
visibilities of the interference patterns emerging at the two output ports are
also different. Hence, in sharp contrast with the symmetric case, here we
should concentrate on one output port and distinguish two possible paths taken
by the particles detected at that port among four paths. It turns out that two
nonorthogonal unsharp observables are measured jointly in this setup. We apply
the condition for joint measurability of these unsharp observables to obtain a
trade-off relation between the fringe visibility of the interference pattern
and the which-path distinguishability.
| arxiv topic:quant-ph |
arxiv_dataset-32211202.3426 | Asymptotic properties of ground states of scalar field equations with a
vanishing parameter
math.AP math-ph math.MP nlin.PS
We study the leading order behaviour of positive solutions of the equation
-\Delta u +\varepsilon u-|u|^{p-2}u+|u|^{q-2}u=0,\qquad x\in\R^N, where $N\ge
3$, $q>p>2$ and when $\varepsilon>0$ is a small parameter. We give a complete
characterization of all possible asymptotic regimes as a function of $p$, $q$
and $N$. The behavior of solutions depends sensitively on whether $p$ is less,
equal or bigger than the critical Sobolev exponent $p^\ast=\frac{2N}{N-2}$. For
$p<p^\ast$ the solution asymptotically coincides with the solution of the
equation in which the last term is absent. For $p>p^\ast$ the solution
asymptotically coincides with the solution of the equation with
$\varepsilon=0$. In the most delicate case $p=p^\ast$ the asymptotic behaviour
of the solutions is given by a particular solution of the critical
Emden--Fowler equation, whose choice depends on $\varepsilon$ in a nontrivial
way.
| arxiv topic:math.AP math-ph math.MP nlin.PS |
arxiv_dataset-32221202.3526 | Quaternary-singlet State of Spin-1 Bosons in Optical Lattice
cond-mat.quant-gas
We present the quantum ground state properties of $^{23}$Na spinor
condensates, which is confined in a periodic or double-well potential and
subject to a magnetic dipole-dipole interaction between nearby wells. A novel
singlet state arise in the system and can be discussed in explicit form. Caused
by the competition between the intra-site spin exchange interactions and the
inter-site dipole-dipole interactions, this quaternary-singlet\ state is a
entangled state formed by at lest four particles and vanish the total spin.
This is distinct from the direct product of the two conventional singlet pairs.
| arxiv topic:cond-mat.quant-gas |
arxiv_dataset-32231202.3626 | Unveiling hidden properties of young star clusters: differential
reddening, star-formation spread and binary fraction
astro-ph.GA
Usually, important parameters of young, low-mass star clusters are very
difficult to obtain by means of photometry, especially when differential
reddening and/or binaries occur in large amounts. We present a semi-analytical
approach that, applied to the Hess diagram of a young star cluster, is able to
retrieve the values of mass, age, star-formation spread, distance modulus,
foreground and differential reddening, and binary fraction. The global
optimisation method known as adaptive simulated annealing (ASA) is used to
minimise the residuals between the observed and simulated Hess diagrams of a
star cluster. The simulations are realistic and take the most relevant
parameters of young clusters into account. Important features of the
simulations are: a normal (Gaussian) differential reddening distribution, a
time-decreasing star-formation rate, the unresolved binaries, and the smearing
effect produced by photometric uncertainties on Hess diagrams. Free parameters
are: cluster mass, age, distance modulus, star-formation spread, foreground and
differential reddening, and binary fraction.
| arxiv topic:astro-ph.GA |
arxiv_dataset-32241202.3726 | Active Semi-Supervised Learning using Submodular Functions
cs.LG stat.ML
We consider active, semi-supervised learning in an offline transductive
setting. We show that a previously proposed error bound for active learning on
undirected weighted graphs can be generalized by replacing graph cut with an
arbitrary symmetric submodular function. Arbitrary non-symmetric submodular
functions can be used via symmetrization. Different choices of submodular
functions give different versions of the error bound that are appropriate for
different kinds of problems. Moreover, the bound is deterministic and holds for
adversarially chosen labels. We show exactly minimizing this error bound is
NP-complete. However, we also introduce for any submodular function an
associated active semi-supervised learning method that approximately minimizes
the corresponding error bound. We show that the error bound is tight in the
sense that there is no other bound of the same form which is better. Our
theoretical results are supported by experiments on real data.
| arxiv topic:cs.LG stat.ML |
arxiv_dataset-32251202.3826 | A new approach to asymptotics of Maclaurin coefficients of algebraic
functions
math.CO
We propose a general method for deriving asymptotics of the Maclaurin series
coefficients of algebraic functions that is based on a procedure of K. V.
Safonov and multivariate singularity analysis. We test the feasibility of this
this approach by experimenting on several examples.
| arxiv topic:math.CO |
arxiv_dataset-32261202.3926 | Exploring Geometric Shapes with Touch
cs.HC
We propose a new technique to help users to explore geometric shapes without
vision. This technique is based on a guidance using directional cues with a pin
array. This is an alternative to the usual technique that consists of raising
the pins corresponding to dark pixels around the cursor. In this paper we
compare the exploration of geometric shapes with our new technique in unimanual
and bimanual conditions. The users made fewer errors in unimanual condition
than in bimanual condition. However they did not explore the shapes more
quickly and there was no difference in confidence in their answer.
| arxiv topic:cs.HC |
arxiv_dataset-32271202.4026 | Accurate reconstruction of insertion-deletion histories by statistical
phylogenetics
q-bio.PE q-bio.GN q-bio.QM
The Multiple Sequence Alignment (MSA) is a computational abstraction that
represents a partial summary either of indel history, or of structural
similarity. Taking the former view (indel history), it is possible to use
formal automata theory to generalize the phylogenetic likelihood framework for
finite substitution models (Dayhoff's probability matrices and Felsenstein's
pruning algorithm) to arbitrary-length sequences. In this paper, we report
results of a simulation-based benchmark of several methods for reconstruction
of indel history. The methods tested include a relatively new algorithm for
statistical marginalization of MSAs that sums over a stochastically-sampled
ensemble of the most probable evolutionary histories. For mammalian
evolutionary parameters on several different trees, the single most likely
history sampled by our algorithm appears less biased than histories
reconstructed by other MSA methods. The algorithm can also be used for
alignment-free inference, where the MSA is explicitly summed out of the
analysis. As an illustration of our method, we discuss reconstruction of the
evolutionary histories of human protein-coding genes.
| arxiv topic:q-bio.PE q-bio.GN q-bio.QM |
arxiv_dataset-32281202.4126 | Hyperfunctions and Spectral Zeta Functions of Laplacians on Self-Similar
Fractals
math-ph math.MP
We investigate the spectral zeta function of fractal differential operators
such as the Laplacian on the unbounded (i.e., infinite) Sierpinski gasket and a
self-similar Sturm-Liouville operator associated with a fractal self-similar
measure on the half-line. In the latter case, C. Sabot discovered the relation
between the spectrum of this operator and the iteration of a rational map of
several complex variables, called the renormalization map. We obtain a
factorization of the spectral zeta function of such an operator, expressed in
terms of the Dirac delta hyperfunction, a geometric zeta function, and the zeta
function associated with the dynamics of the corresponding renormalization map,
viewed either as a polynomial function on the complex plane (in the first case)
or (in the second case) as a polynomial on the complex projective plane. Our
first main result extends to the case of the fractal Laplacian on the unbounded
Sierpinski gasket a factorization formula obtained by the second author for the
spectral zeta function of a fractal string and later extended by A. Teplyaev to
the bounded (i.e., finite) Sierpinski gasket and some other decimable fractals.
Furthermore, our second main result generalizes these factorization formulas to
the renormalization maps of several complex variables associated with fractal
Sturm-Liouville operators. Moreover, as a corollary, in the very special case
when the underlying self-similar measure is Lebesgue measure on [0, 1], we
obtain a representation of the Riemann zeta function in terms of the dynamics
of a certain polynomial in the complex projective plane, thereby extending to
several variables an analogous result by A. Teplyaev.
| arxiv topic:math-ph math.MP |
arxiv_dataset-32291202.4226 | Two-component model in quantum statistical framework compared with
multiplicity distributions in proton-proton collisions at energies up to
$\sqrt {s}$ = 7 TeV
hep-ph hep-ex nucl-ex
Proton-proton collisions at new high energies ($\sqrt {s} =$ 2.36 and 7 TeV)
at LHC resulted into greater mean multiplicities ($<n>$) of charged particles
in the mid-rapidity region than estimated ones by different models and event
generators. Another significant observation in multiplicity data is the change
in slope in the distribution of primary charged hadrons in symmetric
pseudorapidity interval $|\eta|<$2.4. The change is most prominent with data at
$\sqrt{s} = 7$ TeV. These new observations merit further studies. We consider a
two-component model of particle production to analyze multiplicity
distributions of charged hadrons from proton-proton collisions at
centre-of-mass energies $\sqrt{s} = $ 0.9, 2.36 and 7 TeV in symmetric
pseudorapidity intervals $|\eta|$ of increasing width around the centre-of-mass
pseudorapidity $\eta_{cm} = 0$. The model, based on quantum statistical (QS)
formalism, describes multiplicity distribution by convolution of a Negative
Binomial Distribution (NBD), representing a chaotic component, and a Poisson
Distribution (PD), representing a coherent component of particle productions.
The behaviour of characteristic parameters of the model is followed by the LHC
data, while a scaling law, involving information entropy in quantum statistical
viewpoint and derived as a function of chaotic multiplicity obtained from the
two-component model, is not obeyed by the data, satisfactorily. An attempt to
match the measured multiplicity distributions and suggested convolutions with
values of characteristic parameters extracted from the data confirms
disagreement between the data and the model.
| arxiv topic:hep-ph hep-ex nucl-ex |
arxiv_dataset-32301202.4326 | Space-Constrained Interval Selection
cs.DS
We study streaming algorithms for the interval selection problem: finding a
maximum cardinality subset of disjoint intervals on the line. A deterministic
2-approximation streaming algorithm for this problem is developed, together
with an algorithm for the special case of proper intervals, achieving improved
approximation ratio of 3/2. We complement these upper bounds by proving that
they are essentially best possible in the streaming setting: it is shown that
an approximation ratio of $2 - \epsilon$ (or $3 / 2 - \epsilon$ for proper
intervals) cannot be achieved unless the space is linear in the input size. In
passing, we also answer an open question of Adler and Azar \cite{AdlerAzar03}
regarding the space complexity of constant-competitive randomized preemptive
online algorithms for the same problem.
| arxiv topic:cs.DS |
arxiv_dataset-32311202.4426 | A model for the reversal of the toroidal rotation in tokamak
physics.plasm-ph physics.flu-dyn
The transition from toroidal counter- to co- rotation in the core plasma has
been observed at L to H transition in several tokamaks. Spontaneous reversal
has also been observed in TCV beyond a threshold in the density. We develop a
model based on the following phenomenology: (1) the increase of the gradient of
the pressure triggers formation on a fast time scale of cells of convection
(similar to Rayleigh-Benard (RB), but with a single sign of vorticity); (2)
poloidal rotation is induced by the envelope of the peripheric velocity of the
convection cells; via the baroclinic term the gradients of temperature and
density sustain the poloidal rotation against the decay due to the parallel
viscosity; (3) the fast increase of poloidal flow induces a high time
derivative of the radial electric field; (4) the neoclassical polarization
creates a series of parallel accelerations (kiks on each bounce) of the trapped
ions, leading to an increase of the toroidal precession or to its reversal; the
source of energy is the work done by the radial electric field. (5) the
diffusion transfers on resistive scale the toroidal momentum from the trapped
ions to the untrapped ones. The correlated interactions are examined and the
estimated time scales are found to be compatible with the observations.
| arxiv topic:physics.plasm-ph physics.flu-dyn |
arxiv_dataset-32321202.4526 | Dynamics of superconducting nanowires shunted with an external resistor
cond-mat.mes-hall cond-mat.supr-con
We present the first study of superconducting nanowires shunted with an
external resistor, geared towards understanding and controlling coherence and
dissipation in nanowires. The dynamics is probed by measuring the evolution of
the V-I characteristics and the distributions of switching and retrapping
currents upon varying the shunt resistor and temperature. Theoretical analysis
of the experiments indicates that as the value of the shunt resistance is
decreased, the dynamics turns more coherent presumably due to stabilization of
phase-slip centers in the wire and furthermore the switching current approaches
the Bardeen's prediction for equilibrium depairing current. By a detailed
comparison between theory and experimental, we make headway into identifying
regimes in which the quasi-one-dimensional wire can effectively be described by
a zero-dimensional circuit model analogous to the RCSJ (resistively and
capacitively shunted Josephson junction) model of Stewart and McCumber. Besides
its fundamental significance, our study has implications for a range of
promising technological applications.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con |
arxiv_dataset-32331202.4626 | The \v{C}erny conjecture
cs.DM
A word $w$ of letters on edges of underlying graph $\Gamma$ of deterministic
finite automaton (DFA) is called synchronizing if $w$ sends all states of the
automaton to a unique state. J. \v{C}erny discovered in 1964 a sequence of
$n$-state complete DFA possessing a minimal synchronizing word of length
$(n-1)^2$. The hypothesis, well known today as the \v{C}erny conjecture, claims
that it is also precise upper bound on the length of such a word for a complete
DFA. The hypothesis was formulated in 1966 by Starke. The problem has motivated
great and constantly growing number of investigations and generalizations. To
prove the conjecture, we use algebra w on a special class of row monomial
matrices (one unit and rest zeros in every row), induced by words in the
alphabet of labels on edges. These matrices generate a space with respect to
the mentioned operation. The proof is based on connection between length of
words $u$ and dimension of the space generated by solutions $L_x$ of matrix
equation $M_uL_x=M_s$ for synchronizing word $s$, as well as on the relation
between ranks of $M_u$ and $L_x$.
| arxiv topic:cs.DM |
arxiv_dataset-32341202.4726 | A first-principles investigation on the effects of magnetism on the Bain
transformation of $\alpha$-phase FeNi systems
cond-mat.mtrl-sci
The effects of magnetism on the Bain transformation of $\alpha$-phase FeNi
systems are investigated by using the full potential linearized augmented plane
wave (FLAPW) method based on the generalized gradient approximation (GGA). We
found that Ni impurity in bcc Fe increases the lattice constant in
ferromagnetic (FM) states, but not in the nonmagnetic (NM) states. The shear
modulus $G$ and Young's modulus $E$ of bcc Fe are also increased by raising the
concentration of nickel. All the compositions considered show high shear
anisotropy and the ratio of the bulk to shear modulus is greater than 1.75
implying ductility. The mean sound velocities in the $[100]$ directions are
greater than in the $[110]$ directions. The Bain transformation, which is a
component of martensitic transformation, has also been studied to reveal that
Ni$_{x}$Fe$_{1-x}$ alloys are elastically unstable in the NM states, but not so
in the FM states. The electronic structures explain these results in terms of
the density of states at the Fermi level. It is evident that magnetism cannot
be neglected when dealing with the Bain transformation in iron and its alloys.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-32351202.4826 | Global characterization of seismic noise with broadband seismometers
physics.geo-ph
In this paper, we present an analysis of seismic spectra that were calculated
from all broadband channels (BH?) made available through IRIS, NIED F-net and
Orfeus servers covering the past five years and beyond. A general
characterization of the data is given in terms of spectral histograms and
data-availability plots. We show that the spectral information can easily be
categorized in time and regions. Spectral histograms indicate that seismic
stations exist in Africa, Australia and Antarctica that measure spectra
significantly below the global low-noise models above 1 Hz. We investigate
world-wide coherence between the seismic spectra and other data sets like
proximity to cities, station elevation, earthquake frequency, and wind speeds.
Elevation of seismic stations in the US is strongly anti-correlated with
seismic noise near 0.2 Hz and again above 1.5 Hz. Urban settlements are shown
to produce excess noise above 1 Hz, but correlation curves look very different
depending on the region. It is shown that wind speeds can be strongly
correlated with seismic noise above 0.1 Hz, whereas earthquakes produce seismic
noise that shows most clearly in correlation around 80 mHz.
| arxiv topic:physics.geo-ph |
arxiv_dataset-32361202.4926 | Attractor Solutions in f(T) Cosmology
physics.gen-ph
In this paper, we explore the cosmological implications of interacting dark
energy model in a torsion based gravity namely $f(T)$. Assuming dark energy
interacts with dark matter and radiation components, we examine the stability
of this model by choosing different forms of interaction terms. We consider
three different forms of dark energy: cosmological constant, quintessence and
phantom energy. We then obtain several attractor solutions for each dark energy
model interacting with other components. This model successfully explains the
coincidence problem via the interacting dark energy scenario.
| arxiv topic:physics.gen-ph |
arxiv_dataset-32371202.5026 | Forms representing forms and linear spaces on hypersurfaces
math.NT
A generalisation of Waring's problem, considered first by Arkhipov and
Karatsuba, is the question of representing not an integer, but a given
polynomial, as a sum of powers of linear polynomials. We investigate a related
problem and prove a Hasse principle for the number of identical representations
of a set of given forms by homogeneous polynomials of general shape. The result
leads to sizeable improvements for estimates of the number of linear spaces on
the intersection of hypersurfaces.
| arxiv topic:math.NT |
arxiv_dataset-32381202.5126 | Influence of a magnetic guide field on wakefield acceleration
physics.plasm-ph
Enhancement of the trapping and optimization of the beam quality are two key
issues of Laser Wake Field Acceleration (LWFA). The influence of stochastic
acceleration on the trapping of electrons is compared to the one of cold
injection. It is shown that when considering a high intensity wave perturbed by
a low intensity counter-propagating wave, in the non-linear blowout regime, the
influence of the colliding pulses polarizations (either parallel linear or
positive circular) on the beam quality seems weak when the electron density is
below $\sim 10^{-3}$ critical density. The effect of a homogenous constant
magnetic field $B_0$, parallel to the direction of propagation of the pump
pulse, is studied in the blowout regime. Transverse currents are generated at
the rim of the bubble, which results in the amplification of the $B_0$ field at
the rear of the bubble. Without $B_0$ field the beam periodically explodes and
re-confines, this phenomenon is suppressed when $B_0$ reaches some threshold,
which is a function of the laser pulses parameters (intensity, waist,
duration). Therefore the dynamics of the beam is modified, its maximum energy
is slightly boosted and above all transverse emittance reduced. Moreover the
low energy tail, observed in the non magnetized case, can be completely
suppressed leading to very sharp mono-energetic beam when $B_0$ is applied. If
the available $B_0$ field is limited then one has to fine-tune the
spatio-temporal shape and intensity of the colliding pulse in order to get an
acute control on the beam quality.
| arxiv topic:physics.plasm-ph |
arxiv_dataset-32391202.5226 | Confined Dirac Particles in Constant and Tilted Magnetic Field
hep-th cond-mat.mes-hall math-ph math.MP quant-ph
We study the confinement of charged Dirac particles in 3+1 space-time due to
the presence of a constant and tilted magnetic field. We focus on the nature of
the solutions of the Dirac equation and on how they depend on the choice of
vector potential that gives rise to the magnetic field. In particular, we
select a "Landau gauge" such that the momentum is conserved along the direction
of the vector potential yielding spinor wavefunctions, which are localized in
the plane containing the magnetic field and normal to the vector potential.
These wave functions are expressed in terms of the Hermite polynomials. We
point out the relevance of these findings to the relativistic quantum Hall
effect and compare with the results obtained for a constant magnetic field
normal to the plane in 2+1 dimensions.
| arxiv topic:hep-th cond-mat.mes-hall math-ph math.MP quant-ph |
arxiv_dataset-32401202.5326 | Observing trajectories with weak measurements in quantum systems in the
semiclassical regime
quant-ph
We propose a scheme allowing to observe the evolution of a quantum system in
the semiclassical regime along the paths generated by the propagator. The
scheme relies on performing consecutive weak measurements of the position. We
show how weak trajectories" can be extracted from the pointers of a series of
measurement devices having weakly interacted with the system. The properties of
these "weak trajectories" are investigated and illustrated in the case of a
time-dependent model system.
| arxiv topic:quant-ph |
arxiv_dataset-32411202.5426 | Hard analysis meets critical knots (Stationary points of the Moebius
energy are smooth)
math.AP
We prove that if a curve parametrized by arc length is a stationary point of
the Moebius energy introduced by Jun O'Hara, then it is smooth whenever the
Moebius energy is finite. Our methods, interestingly, only rely on purely
analytical arguments, entirely without using Moebius invariance. Furthermore,
the techniques involved are not fundamentally restricted to one-dimensional
domains, but are generalizable to arbitrary dimensions.
| arxiv topic:math.AP |
arxiv_dataset-32421202.5526 | Shockley model description of surface states in topological insulators
cond-mat.str-el cond-mat.mes-hall
We show that the surface states in topological insulators can be understood
based on a well-known Shockley model, a one-dimensional tight-binding model
with two atoms per elementary cell, connected via alternating tunneling
amplitudes. We generalize the one-dimensional model to the three-dimensional
case corresponding to the sequence of layers connected via the amplitudes,
which depend on the in-plane momentum p = (p_x,p_y). The Hamiltonian of the
model is described a (2 x 2) Hamiltonian with the off-diagonal element t(k,p)
depending also on the out-of-plane momentum k. We show that the complex
function t(k,p) defines the properties of the surface states. The surface
states exist for the in-plane momenta p, where the winding number of the
function t(k,p) is non-zero as k is changed from 0 to 2pi. The sign of the
winding number defines the sublattice on which the surface states are
localized. The equation t(k,p)=0 defines a vortex line in the three-dimensional
momentum space. The projection of the vortex line on the two-dimensional
momentum p space encircles the domain where the surface states exist. We
illustrate how our approach works for a well-known TI model on a diamond
lattice. We find that different configurations of the vortex lines are
responsible for the "weak" and "strong" topological insulator phases. The phase
transition occurs when the vortex lines reconnect from spiral to circular form.
We discuss the Shockley model description of Bi_2Se_3 and the applicability of
the continuous approximation for the description of the topological edge
states. We conclude that the tight-binding model gives a better description of
the surface states.
| arxiv topic:cond-mat.str-el cond-mat.mes-hall |
arxiv_dataset-32431202.5626 | Some Characterizations of a Normal Subgroup of a Group
math.GR
Let G be a group and H be a subgroup of G which is either finite or of finite
index in G. In this note, we give some characterizations for normality of H in
G. As a consequence we get a very short and elementary proof of the Main
Theorem of [5], which avoids the use of the classification of finite simple
groups
| arxiv topic:math.GR |
arxiv_dataset-32441202.5726 | Mean-field equations for higher-order quantum statistical models : an
information geometric approach
quant-ph cond-mat.stat-mech
This work is a simple extension of \cite{NNjpa}. We apply the concepts of
information geometry to study the mean-field approximation for a general class
of quantum statistical models namely the higher-order quantum Boltzmann
machines (QBMs). The states we consider are assumed to have at most third-order
interactions with deterministic coupling coefficients. Such states, taken
together, can be shown to form a quantum exponential family and thus can be
viewed as a smooth manifold. In our work, we explicitly obtain naive mean-field
equations for the third-order classical and quantum Boltzmann machines and
demonstrate how some information geometrical concepts, particularly,
exponential and mixture projections used to study the naive mean-field
approximation in \cite{NNjpa} can be extended to a more general case. Though
our results do not differ much from those in \cite{NNjpa}, we emphasize the
validity and the importance of information geometrical point of view for higher
dimensional classical and quantum statistical models.
| arxiv topic:quant-ph cond-mat.stat-mech |
arxiv_dataset-32451202.5826 | Proceedings 7th Workshop on Model-Based Testing
cs.SE
This volume contains the proceedings of the Seventh Workshop on Model-Based
Testing (MBT 2012), which was held on 25 March, 2012 in Tallinn, Estonia, as a
satellite event of the European Joint Conferences on Theory and Practice of
Software, ETAPS 2012.
The workshop is devoted to model-based testing of both software and hardware.
Model-based testing uses models describing the required behavior of the system
under consideration to guide such efforts as test selection and test results
evaluation. Testing validates the real system behavior against models and
checks that the implementation conforms to them, but is capable also to find
errors in the models themselves.
The first MBT workshop was held in 2004, in Barcelona. At that time MBT
already had become a hot topic, but the MBT workshop was the first event
devoted mostly to this topic. Since that time the area has generated enormous
scientific interest, and today there are several specialized workshops and more
broad conferences on software and hardware design and quality assurance
covering model based testing. MBT has become one of the most powerful system
analysis tools, one of the latest hot topic related is applying MBT in security
analysis and testing. MBT workshop tries to keep up with current trends. In
2012 "industrial paper" category was added to the program and two industrial
papers were accepted by the program committee.
| arxiv topic:cs.SE |
arxiv_dataset-32461202.5926 | Second-order Price Dynamics: Approach to Equilibrium with Perpetual
Arbitrage
q-fin.GN
The notion that economies should normally be in equilibrium is by now
well-established; equally well-established is that economies are almost never
precisely in equilibrium. Using a very general formulation, we show that under
dynamics that are second-order in time a price system can remain away from
equilibrium with permanent and repeating opportunities for arbitrage, even when
a damping term drives the system towards equilibrium. We also argue that
second-order dynamic equations emerge naturally when there are heterogeneous
economic actors, some behaving as active and knowledgeable arbitrageurs, and
others using heuristics. The essential mechanism is that active arbitrageurs
are able to repeatedly benefit from the suboptimal heuristics that govern most
economic behavior.
| arxiv topic:q-fin.GN |
arxiv_dataset-32471202.6026 | The electromagnetic model of short GRBs, the nature of prompt tails,
supernova-less long GRBs and highly efficient episodic accretion
astro-ph.HE
Many short GRBs show prompt tails lasting up to hundreds of seconds that can
be energetically dominant over the initial sub-second spike. In this paper we
develop an electromagnetic model of short GRBs that explains the two stages of
the energy release, the prompt spike and the prompt tail. The key ingredient of
the model is the recent discovery that an isolated black hole can keep its open
magnetic flux for times much longer than the collapse time and, thus, can
spin-down electromagnetically, driving the relativistic wind.
First, the merger is preceded by an electromagnetic precursor wind. If a
fraction of the wind power is converted into pulsar-like coherent radio
emission, this may produce an observable radio burst of few milliseconds.
At the active stage of the merger, two neutron stars produces a black hole
surrounded by an accretion torus in which the amplified magnetic field extracts
the rotational energy of the black hole and drives an axially-collimated
electromagnetic wind. For observers nearly aligned with the orbital normal this
is seen as a classical short GRB.
After the accretion of the torus, the isolated black hole keeps the open
magnetic flux and drives the equatorially (not axially) collimated outflow,
which is seen by an observer at intermediate polar angles as a prompt tail. The
tail carries more energy than the prompt spike, but its emission is de-boosted
for observers along the orbital normal. Observers in the equatorial plane miss
the prompt spike and interpret the prompt tail as an energetic supernova-less
long GRB.
We also demonstrate that episodic accretion onto the BH of magnetized clouds
that carry non-zero magnetic flux can be highly efficient in extracting the
spin energy of the BH, producing the outflows with the power exceeding the
average accretion power.
| arxiv topic:astro-ph.HE |
arxiv_dataset-32481202.6126 | Constraint-Based Heuristic On-line Test Generation from
Non-deterministic I/O EFSMs
cs.SE
We are investigating on-line model-based test generation from
non-deterministic output-observable Input/Output Extended Finite State Machine
(I/O EFSM) models of Systems Under Test (SUTs). We propose a novel
constraint-based heuristic approach (Heuristic Reactive Planning Tester (xRPT))
for on-line conformance testing non-deterministic SUTs. An indicative feature
of xRPT is the capability of making reasonable decisions for achieving the test
goals in the on-line testing process by using the results of off-line bounded
static reachability analysis based on the SUT model and test goal
specification. We present xRPT in detail and make performance comparison with
other existing search strategies and approaches on examples with varying
complexity.
| arxiv topic:cs.SE |
arxiv_dataset-32491202.6226 | Suzaku X-Ray Observation of the Dwarf Nova Z Camelopardalis at the Onset
of an Optical Outburst
astro-ph.HE
We present the result of a Suzaku X-ray spectroscopic observation of the
dwarf nova Z Camelopardalis, which was conducted by chance at the onset of an
optical outburst. We used the X-ray Imaging Spectrometer (a 38 ks exposure) and
the Hard X-ray Detector (34 ks) to obtain a 0.35-40 keV spectrum
simultaneously. Spectral characteristics suggest that the source was in the
X-ray quiescent state despite being in the rising phase of an outburst in the
optical band. The spectrum shows a clear signature of circumstellar absorption
in excess of interstellar absorption and the reprocessed emission features of
Fe fluorescence and Compton scattering. The extra absorption is explained due
to partial coverage by either neutral or ionized matter. We found a spectral
change during the observation, which is attributable only to the change in the
circumstellar absorption. Such an X-ray spectral variation is reported for the
first time in dwarf novae. We speculate that the variation in the circumstellar
absorption is interpreted as a time-varying disk wind or geometrically flaring
disk around the white dwarf during the propagation of a heat wave inward along
the accretion disk at the beginning of the outburst, in which optical outburst
and X-ray quiescent states co-exist.
| arxiv topic:astro-ph.HE |
arxiv_dataset-32501202.6326 | Parallel processing in immune networks
q-bio.CB cond-mat.dis-nn cond-mat.stat-mech physics.bio-ph
In this work we adopt a statistical mechanics approach to investigate basic,
systemic features exhibited by adaptive immune systems. The lymphocyte network
made by B-cells and T-cells is modeled by a bipartite spin-glass, where,
following biological prescriptions, links connecting B-cells and T-cells are
sparse. Interestingly, the dilution performed on links is shown to make the
system able to orchestrate parallel strategies to fight several pathogens at
the same time; this multitasking capability constitutes a remarkable, key
property of immune systems as multiple antigens are always present within the
host. We also define the stochastic process ruling the temporal evolution of
lymphocyte activity, and show its relaxation toward an equilibrium measure
allowing statistical mechanics investigations. Analytical results are compared
with Monte Carlo simulations and signal-to-noise outcomes showing overall
excellent agreement. Finally, within our model, a rationale for the
experimentally well-evidenced correlation between lymphocytosis and
autoimmunity is achieved; this sheds further light on the systemic features
exhibited by immune networks.
| arxiv topic:q-bio.CB cond-mat.dis-nn cond-mat.stat-mech physics.bio-ph |
arxiv_dataset-32511202.6426 | Semi-analytic method for slow light photonic crystal waveguide design
physics.optics
We present a semi-analytic method to calculate the dispersion curves and the
group velocity of photonic crystal waveguide modes in two-dimensional
geometries. We model the waveguide as a homogenous strip, surrounded by
photonic crystal acting as diffracting mirrors. Following conventional
guided-wave optics, the properties of the photonic crystal waveguide may be
calculated from the phase upon propagation over the strip and the phase upon
reflection. The cases of interest require a theory including the specular order
and one other diffracted reflected order. The computational advantages let us
scan a large parameter space, allowing us to find novel types of solutions.
| arxiv topic:physics.optics |
arxiv_dataset-32521202.6526 | State Concentration Exponent as a Measure of Quickness in Kauffman-type
Networks
cond-mat.dis-nn nlin.AO
We study the dynamics of randomly connected networks composed of binary
Boolean elements and those composed of binary majority vote elements. We
elucidate their differences in both sparsely and densely connected cases. The
quickness of large network dynamics is usually quantified by the length of
transient paths, an analytically intractable measure. For discrete-time
dynamics of networks of binary elements, we address this dilemma with an
alternative unified framework by using a concept termed state concentration,
defined as the exponent of the average number of t-step ancestors in state
transition graphs. The state transition graph is defined by nodes corresponding
to network states and directed links corresponding to transitions. Using this
exponent, we interrogate the dynamics of random Boolean and majority vote
networks. We find that extremely sparse Boolean networks and majority vote
networks with arbitrary density achieve quickness, owing in part to long-tailed
in-degree distributions. As a corollary, only relatively dense majority vote
networks can achieve both quickness and robustness.
| arxiv topic:cond-mat.dis-nn nlin.AO |
arxiv_dataset-32531202.6626 | Adiabatic state preparation of interacting two-level systems
cond-mat.mes-hall quant-ph
We consider performing adiabatic rapid passage (ARP) using frequency-swept
driving pulses to excite a collection of interacting two-level systems. Such a
model arises in a wide range of many-body quantum systems, such as cavity QED
or quantum dots, where a nonlinear component couples to light. We analyze the
one-dimensional case using the Jordan-Wigner transformation, as well as the
mean field limit where the system is described by a Lipkin-Meshkov-Glick
Hamiltonian. These limits provide complementary insights into the behavior of
many-body systems under ARP, suggesting our results are generally applicable.
We demonstrate that ARP can be used for state preparation in the presence of
interactions, and identify the dependence of the required pulse shapes on the
interaction strength. In general interactions increase the pulse bandwidth
required for successful state transfer, introducing new restrictions on the
pulse forms required.
| arxiv topic:cond-mat.mes-hall quant-ph |
arxiv_dataset-32541203.0041 | Matrix-valued orthogonal polynomials related to (SU(2)\times
SU(2),diag), II
math.CA math.RT
In a previous paper we have introduced matrix-valued analogues of the
Chebyshev polynomials by studying matrix-valued spherical functions on
SU(2)\times SU(2). In particular the matrix-size of the polynomials is
arbitrarily large. The matrix-valued orthogonal polynomials and the
corresponding weight function are studied. In particular, we calculate the
LDU-decomposition of the weight where the matrix entries of L are given in
terms of Gegenbauer polynomials. The monic matrix-valued orthogonal polynomials
P_n are expressed in terms of Tirao's matrix-valued hypergeometric function
using the matrix-valued differential operator of first and second order to
which the P_n's are eigenfunctions. From this result we obtain an explicit
formula for coefficients in the three-term recurrence relation satisfied by the
polynomials P_n. These differential operators are also crucial in expressing
the matrix entries of P_nL as a product of a Racah and a Gegenbauer polynomial.
We also present a group theoretic derivation of the matrix-valued differential
operators by considering the Casimir operators corresponding to SU(2)\times
SU(2).
| arxiv topic:math.CA math.RT |
arxiv_dataset-32551203.0141 | Continuous Percolation Phase Transitions of Two-dimensional Lattice
Networks under a Generalized Achlioptas Process
cond-mat.stat-mech
The percolation phase transitions of two-dimensional lattice networks under a
generalized Achlioptas process (GAP) are investigated. During the GAP, two
edges are chosen randomly from the lattice and the edge with minimum product of
the two connecting cluster sizes is taken as the next occupied bond with a
probability $p$. At $p=0.5$, the GAP becomes the random growth model and leads
to the minority product rule at $p=1$. Using the finite-size scaling analysis,
we find that the percolation phase transitions of these systems with $0.5 \le p
\le 1$ are always continuous and their critical exponents depend on $p$.
Therefore, the universality class of the critical phenomena in two-dimensional
lattice networks under the GAP is related to the probability parameter $p$ in
addition.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-32561203.0241 | Observations of Cool-Star Magnetic Fields
astro-ph.SR astro-ph.IM
Cool stars like the Sun harbor convection zones capable of producing
substantial surface magnetic fields leading to stellar magnetic activity. The
influence of stellar parameters like rotation, radius, and age on cool-star
magnetism, and the importance of the shear layer between a radiative core and
the convective envelope for the generation of magnetic fields are keys for our
understanding of low-mass stellar dynamos, the solar dynamo, and also for other
large-scale and planetary dynamos. Our observational picture of cool-star
magnetic fields has improved tremendously over the last years. Sophisticated
methods were developed to search for the subtle effects of magnetism, which are
difficult to detect particularly in cool stars. With an emphasis on the
assumptions and capabilities of modern methods used to measure magnetism in
cool stars, I review the different techniques available for magnetic field
measurements. I collect the analyses on cool-star magnetic fields and try to
compare results from different methods, and I review empirical evidence that
led to our current picture of magnetic fields and their generation in cool
stars and brown dwarfs.
| arxiv topic:astro-ph.SR astro-ph.IM |
arxiv_dataset-32571203.0341 | Modeling Multi-Wavelength Stellar Astrometry. III. Determination of the
Absolute Masses of Exoplanets and Their Host Stars
astro-ph.SR
Astrometric measurements of stellar systems are becoming significantly more
precise and common, with many ground and space-based instruments and missions
approaching 1 microarcsecond precision. We examine the multi-wavelength
astrometric orbits of exoplanetary systems via both analytical formulae and
numerical modeling. Exoplanets have a combination of reflected and thermally
emitted light that cause the photocenter of the system to shift increasingly
farther away from the host star with increasing wavelength. We find that, if
observed at long enough wavelengths, the planet can dominate the astrometric
motion of the system, and thus it is possible to directly measure the orbits of
both the planet and star, and thus directly determine the physical masses of
the star and planet, using multi-wavelength astrometry. In general, this
technique works best for, though is certainly not limited to, systems that have
large, high-mass stars and large, low-mass planets, which is a unique parameter
space not covered by other exoplanet characterization techniques. Exoplanets
that happen to transit their host star present unique cases where the physical
radii of the planet and star can be directly determined via astrometry alone.
Planetary albedos and day-night contrast ratios may also be probed via this
technique due to the unique signature they impart on the observed astrometric
orbits. We develop a tool to examine the prospects for near-term detection of
this effect, and give examples of some exoplanets that appear to be good
targets for detection in the K to N infrared observing bands, if the required
precision can be achieved.
| arxiv topic:astro-ph.SR |
arxiv_dataset-32581203.0441 | Existence, uniqueness and a priori estimates for a non linear
integro-differential equation
math-ph cond-mat.dis-nn cond-mat.supr-con math.MP q-bio.NC
The paper deals with the explicit calculus and the properties of the
fundamental solution K of a parabolic operator related to a semilinear equation
that models reaction diffusion systems with excitable kinetics. The initial
value problem in all of the space is analyzed together with continuous
dependence and a priori estimates of the solution. These estimates show that
the asymptotic behavior is determined by the reaction mechanism. Moreover it's
possible a rigorous singular perturbation analysis for discussing travelling
waves with their characteristic times.
| arxiv topic:math-ph cond-mat.dis-nn cond-mat.supr-con math.MP q-bio.NC |
arxiv_dataset-32591203.0541 | Hypothesis Testing and Decision Theoretic Approach for Fault Detection
in Wireless Sensor Networks
cs.NI stat.AP
Sensor networks aim at monitoring their surroundings for event detection and
object tracking. But due to failure or death of sensors, false signal can be
transmitted. In this paper, we consider the problem of fault detection in
wireless sensor network (WSN), in particular, addressing both the noise-related
measurement error and sensor fault simultaneously in fault detection. We assume
that the sensors are placed at the center of a square (or hexagonal) cell in
region of interest (ROI) and, if the event occurs, it occurs at a particular
cell of the ROI. We propose fault detection schemes that take into account
error probabilities into the optimal event detection process. We develop the
schemes under the consideration of Neyman-Pearson test and Bayes test.
| arxiv topic:cs.NI stat.AP |
arxiv_dataset-32601203.0641 | A simple proof of Schmidt-Summerer's inequality
math.NT
In this paper we give a simple proof of an inequality for intermediate
Diophantine exponents obtained recently by W. M. Schmidt and L. Summerer.
| arxiv topic:math.NT |
arxiv_dataset-32611203.0741 | Unbiased flux calibration methods for spectral-line radio observations
astro-ph.IM
Position and frequency switching techniques used for the removal of the
bandpass dependence of radio astronomical spectra are presented and discussed
in detail. Both methods are widely used, although the frequency dependence of
the system temperature and/or noise diode is often neglected. This leads to
systematic errors in the calibration that potentially have a significant impact
on scientific results, especially when using large-bandwidth receivers or
performing statistical analyses. We present methods to derive an unbiased
calibration using a noise diode, which is part of many heterodyne receivers. We
compare the proposed methods and describe the advantages and bottlenecks of the
various approaches. Monte Carlo simulations are used to qualitatively
investigate both systematics and the error distribution of the reconstructed
flux estimates about the correct flux values for the new methods but also the
'classical' case. Finally, the determination of the frequency-dependent noise
temperature of the calibration diode using hot-cold measurements or
observations of well-known continuum sources is also briefly discussed.
| arxiv topic:astro-ph.IM |
arxiv_dataset-32621203.0841 | How much could we cover a set by c.e sets?
cs.FL cs.CC
"How much c.e. sets could cover a given set?" in this paper we are going to
answer this question. Also, in this approach some old concepts come into a new
arrangement. The major goal of this article is to introduce an appropriate
definition for this purpose. Introduction In Computability Theory (Recursion
Theory) in the first step we wish to recognize the sets which could be
enumerated by Turing machines (equivalently, algorithms) and in the next step
we will compare these sets by some reasonable order (Like Turing degree). Also
sometimes with some extra information (Oracles) a class of non c.e. sets show
the same behavior as c.e. sets (Post hierarchy and related theorems). Here we
try another approach: "Let A be an arbitrary set and we wish to recognize how
much this set might be covered by a c.e. set?" Although in some sense this
approach could be seen in some definitions of Recursion Theory, but at the best
of our knowledge it didn't considered as an approach yet, even though it is
able to shed a light on some subjects of Computability of sets. Defining this
approach is not quite straightforward and there are some obstacles to define
them. To overcome these difficulties we modify the definitions. We have an
alternative problem here when we consider recursive sets and not c.e. sets. In
this case, the problem would be: "Let A be an arbitrary set and we wish to know
that how much this set might be covered by a recursive Set?" Here, we try the
first definition and the first problem.
| arxiv topic:cs.FL cs.CC |
arxiv_dataset-32631203.0941 | Charge-exchange emission in the starburst galaxies M82 and NGC3256
astro-ph.HE
Charge-exchange (CE) emission produces features which are detectable with the
current X-ray instrumentation in the brightest near galaxies. We describe these
aspects in the observed X-ray spectra of the star forming galaxies M82 and NGC
3256, from the Suzaku and XMM-Newton telescopes. Emission from both ions (O, C)
and neutrals (Mg, Si) is recognised. We also describe how microcalorimeter
instrumentation on future missions will improve CE observations.
| arxiv topic:astro-ph.HE |
arxiv_dataset-32641203.1041 | LHC Discovery Potential for Non-Standard Higgs Bosons in the 3b Channel
hep-ph
In a variety of well motivated models, such as two Higgs Doublet Models
(2HDMs) and the Minimal Supersymmetric Standard Model (MSSM), there are neutral
Higgs bosons that have significantly enhanced couplings to b-quarks and tau
leptons in comparison to those of the SM Higgs. These so called non-standard
Higgs bosons could be copiously produced at the LHC in association with b
quarks, and subsequently decay into b-quark pairs. However, this production
channel suffers from large irreducible QCD backgrounds. We propose a new search
strategy for non-standard neutral Higgs bosons at the 7 TeV LHC in the 3b's
final state topology. We perform a simulation of the signal and backgrounds,
using state of the art tools and methods for different sets of selection cuts,
and conclude that neutral Higgs bosons with couplings to b-quarks of about 0.3
or larger, and masses up to 400 GeV, could be seen with a luminosity of 30
fb^{-1}. In the case of the MSSM we also discuss the complementarity between
the 3b channel and the inclusive tau pair channel in exploring the
supersymmetric parameter space.
| arxiv topic:hep-ph |
arxiv_dataset-32651203.1141 | Superburst with Outburst from EXO 1745-248 in Terzan 5 with MAXI
astro-ph.HE
MAXI/GSC detected a superburst from EXO 1745-248 in the globular cluster
Terzan 5 on 2011 October 24. The GSC light curve shows an exponential decay
with an e-folding time of 0.3 day. The spectra are consistent with the
blackbody radiation, whose temperature is 2.2 keV and 1.2 keV at MJD 55858.56
and 55859.20, respectively. The fluence is $1.4 \times 10^{42}$ erg in 2-20 keV
assuming 8.7 kpc distance. The sphere radius of the blackbody and its
luminosity are estimated to be 6.2 km and $1.1 \times 10^{38}$ erg s$^{-1}$,
respectively, from the spectral fitting at the flux peak. Those e-folding time,
temperature, softening, fluence, and radius are typical of superbursts from the
low-mass X-ray binaries. The superburst was followed by an outburst 28 hours
after the superburst onset. The outburst lasted for 5 days and the fluence was
$4.3 \times 10^{42}$ erg. The instability of the accretion disk caused by the
superburst would be an explanation for the outburst, whereas the mass accretion
of the matter evaporated from surface of the companion star by the superburst
would be another possibility.
| arxiv topic:astro-ph.HE |
arxiv_dataset-32661203.1241 | Three particles in a finite volume
hep-lat hep-ph nucl-th
Within the non-relativistic potential scattering theory, we derive a
generalized version of the L\"uscher formula, which includes three-particle
inelastic channels. Faddeev equations in a finite volume are discussed in
detail. It is proved that, even in the presence of the three-particle
intermediate states, the discrete spectrum in a finite box is determined by the
infinite-volume elements of the scattering S-matrix up to corrections,
exponentially suppressed at large volumes.
| arxiv topic:hep-lat hep-ph nucl-th |
arxiv_dataset-32671203.1341 | Associated production of charged Higgs bosons and top quarks with POWHEG
hep-ph hep-ex
The associated production of charged Higgs bosons and top quarks at hadron
colliders is an important discovery channel to establish the existence of a
non-minimal Higgs sector. Here, we present details of a next-to-leading order
(NLO) calculation of this process using the Catani-Seymour dipole formalism and
describe its implementation in POWHEG, which allows to match NLO calculations
to parton showers. Numerical predictions are presented using the PYTHIA parton
shower and are compared to those obtained previously at fixed order, to a
leading order calculation matched to the PYTHIA parton shower, and to a
different NLO calculation matched to the HERWIG parton shower with MC@NLO. We
also present numerical predictions and theoretical uncertainties for various
Two Higgs Doublet Models at the Tevatron and LHC.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-32681203.1441 | Boundedness of fractional integral operators with rough kernels on
weighted Morrey spaces
math.CA
Let $M_{\Omega,\alpha}$ and $T_{\Omega,\alpha}$ be the fractional maximal and
integral operators with rough kernels, where $0<\alpha<n$. In this paper, we
shall study the continuity properties of $M_{\Omega,\alpha}$ and
$T_{\Omega,\alpha}$ on the weighted Morrey spaces $L^{p,\kappa}(w)$. The
boundedness of their commutators with BMO functions is also obtained.
| arxiv topic:math.CA |
arxiv_dataset-32691203.1541 | On Murayama's theorem on extensor properties of G-spaces of given orbit
types
math.GT math.GN
We develop a method of extending actions of compact transformation groups
which is then applied to the problem of preservation of equivariant extensor
property by passing to a subspace of given orbit types.
| arxiv topic:math.GT math.GN |
arxiv_dataset-32701203.1641 | Exploring the unusually high black hole-to-bulge mass ratios in NGC4342
and NGC4291: the asynchronous growth of bulges and black holes
astro-ph.CO
We study two nearby, early-type galaxies, NGC4342 and NGC4291, that host
unusually massive black holes relative to their low stellar mass. The observed
black hole-to-bulge mass ratios of NGC4342 and NGC4291 are ~6.9% and ~1.9%,
respectively, which significantly exceed the typical observed ratio of ~0.2%.
As a consequence of the exceedingly large black hole-to-bulge mass ratios,
NGC4342 and NGC4291 are ~5.1 sigma and ~3.4 sigma outliers from the M_BH -
M_bulge scaling relation, respectively. In this paper, we explore the origin of
the unusually high black hole-to-bulge mass ratio. Based on Chandra X-ray
observations of the hot gas content of NGC4342 and NGC4291, we compute
gravitating mass profiles, and conclude that both galaxies reside in massive
dark matter halos, which extend well beyond the stellar light. The presence of
dark matter halos around NGC4342 and NGC4291 and a deep optical image of the
environment of NGC4342 indicate that tidal stripping, in which >90% of the
stellar mass was lost, cannot explain the observed high black hole-to-bulge
mass ratios. Therefore, we conclude that these galaxies formed with low stellar
masses, implying that the bulge and black hole did not grow in tandem. We also
find that the black hole mass correlates well with the properties of the dark
matter halo, suggesting that dark matter halos may play a major role in
regulating the growth of the supermassive black holes.
| arxiv topic:astro-ph.CO |
arxiv_dataset-32711203.1741 | Gradient flows with jumps associated with nonlinear Hamilton-Jacobi
equations with jumps
math.AP
We analyze gradient flows with jumps generated by a finite set of complete
vector fields in involution using some Radon measures $u\in \mathcal{U}_a$ as
admissible perturbations. Both the evolution of a bounded gradient flow
$\{x^u(t,\l)\in B(x^*,3\g)\subseteq \mbn: \,t\in[0,T],\,\l\in B(x^*,2\g)\}$ and
the unique solution $\l=\psi^u(t,x)\in B(x^*,2\g)\subseteq \mbn$ of integral
equation $x^u(t,\l)=x\in B(x^*,\g), \,t\in[0,T]$, are described using the
corresponding gradient representation associated with flow and Hamilton-jacobi
equations.
| arxiv topic:math.AP |
arxiv_dataset-32721203.1841 | Low power sessile droplet actuation via modulated surface acoustic waves
physics.flu-dyn
Low power actuation of sessile droplets is of primary interest for portable
or hybrid lab-on-a-chip and harmless manipulation of biofluids. In this paper,
we show that the acoustic power required to move or deform droplets via surface
acoustic waves can be substantially reduced through the forcing of the drops
inertio-capillary modes of vibrations. Indeed, harmonic, superharmonic and
subharmonic (parametric) excitation of these modes are observed when the high
frequency acoustic signal (19.5 MHz) is modulated around Rayleigh-Lamb
inertio-capillary frequencies. This resonant behavior results in larger
oscillations and quicker motion of the drops than in the non-modulated case.
| arxiv topic:physics.flu-dyn |
arxiv_dataset-32731203.1941 | A New Extensive Library of Synthetic Stellar Spectra from PHOENIX
Atmospheres and its Application to Fitting VLT MUSE Spectra
astro-ph.SR
We present a new library of synthetic spectra based on the stellar atmosphere
code PHOENIX. It covers the wavelength range from 500{\AA} to 55000{\AA} with a
resolution of R=500000 in the optical and near IR, R=100000 in the IR and
{\Delta}{\lambda}=0.1{\AA} in the UV. The parameter space covers
2300K<=Teff<=8000K, 0.0<=log(g)<=6.0, -4.0<=[Fe/H]<=+1.0 and
-0.3<=[{\alpha}/Fe]<=+0.8. The library is work-in-progress and going to be
extended to at least Teff=25000K. We use a new self-consistent way of
describing the microturbulence for our model atmospheres. The entire library of
synthetic spectra will be available for download. Futhermore we present a
method for fitting spectra, especially designed to work with the new 2nd
generation VLT instrument MUSE. We show that we can determine stellar
parameters (Teff, log(g), [Fe/H] and [{\alpha}/Fe]) and even single element
abundances.
| arxiv topic:astro-ph.SR |
arxiv_dataset-32741203.2041 | Towards MAC/Anycast Diversity in IEEE 802.11n MIMO Networks
cs.NI
Opportunistic Routing (OR) is a novel routing technique for wireless mesh
networks that exploits the broadcast nature of the wireless medium. OR combines
frames from multiple receivers and therefore creates a form of Spatial
Diversity, called MAC Diversity. The gain from OR is especially high in
networks where the majority of links has a high packet loss probability. The
updated IEEE 802.11n standard improves the physical layer with the ability to
use multiple transmit and receive antennas, i.e. Multiple-Input and
Multiple-Output (MIMO), and therefore already offers spatial diversity on the
physical layer, i.e. called Physical Diversity, which improves the reliability
of a wireless link by reducing its error rate. In this paper we quantify the
gain from MAC diversity as utilized by OR in the presence of PHY diversity as
provided by a MIMO system like 802.11n. We experimented with an IEEE 802.11n
indoor testbed and analyzed the nature of packet losses. Our experiment results
show negligible MAC diversity gains for both interference-prone 2.4 GHz and
interference-free 5 GHz channels when using 802.11n. This is different to the
observations made with single antenna systems based on 802.11b/g, as well as in
initial studies with 802.11n.
| arxiv topic:cs.NI |
arxiv_dataset-32751203.2141 | Sur la cohomologie non ramifi\'ee en degr\'e trois d'un produit
math.AG math.NT
Let F be a finite field and let C be a smooth projective curve over F. For
some smooth projective surfaces X over F we establish that the third unramified
cohomology of the product of X and C vanishes. This applies in particular to
geometrically rational surfaces.
Soit F un corps fini et soit C une courbe projective et lisse sur F. Pour
certaines surfaces projectives et lisses X sur F on \'etablit la nullit\'e du
troisi\`eme groupe de cohomologie non ramifi\'ee du produit de X et C. Cela
s'applique en particulier aux surfaces g\'eom\'etriquement rationnelles.
| arxiv topic:math.AG math.NT |
arxiv_dataset-32761203.2241 | Model-Checking of Linear-Time Properties Based on Possibility Measure
cs.LO
We study the LTL model-checking in possibilistic Kripke structure using
possibility measure. First, the notion of possibilistic Kripke structure and
the related possibility measure are introduced, then model-checking of
reachability and repeated reachability linear-time properties in finite
possibilistic Kripke structure are studied. Standard safety property and
-regular property in possibilistic Kripke structure are introduced, the
verification of regular safety property and -regular property using finite
automata are thoroughly studied. It has been shown that the verification of
regular safety property and -regular property in finite possibilistic Kripke
structure can be transformed into the verification of reachability property and
repeated reachability property in the product possibilistic Kripke structure
introduced in this paper. Several examples are given to illustrate the methods
presented in the paper.
| arxiv topic:cs.LO |
arxiv_dataset-32771203.2341 | Replica theory of the rigidity of structural glasses
cond-mat.soft cond-mat.dis-nn cond-mat.stat-mech
We present a first principle scheme to compute the rigidity, i. e. the
shear-modulus of structural glasses at finite temperatures using the cloned
liquid theory, which combines the replica theory and the liquid theory. With
the aid of the replica method which enables disentanglement of thermal
fluctuations in liquids into intra-state and inter-state fluctuations, we
extract the rigidity of metastable amorphous solid states in the supercooled
liquid and glass phases. The result can be understood intuitively without
replicas. As a test case, we apply the scheme to the supercooled and glassy
state of a binary mixture of soft-spheres. The result compares well with the
shear-modulus obtained by a previous molecular dynamic simulation. The rigidity
of metastable states is significantly reduced with respect to the instantaneous
rigidity, namely the Born term, due to non-affine responses caused by
displacements of particles inside cages at all temperatures down to T=0. It
becomes nearly independent of temperature below the Kauzmann temperature T_K.
At higher temperatures in the supercooled liquid state, the non-affine
correction to the rigidity becomes stronger suggesting melting of the
metastable solid state. Inter-state part of the static response implies jerky,
intermittent stress-strain curves with static analogue of yielding at
mesoscopic scales.
| arxiv topic:cond-mat.soft cond-mat.dis-nn cond-mat.stat-mech |
arxiv_dataset-32781203.2441 | Widely-tunable mid-IR frequency comb source based on difference
frequency generation
physics.optics
We report on a mid-infrared frequency comb source of unprecedented tunability
covering the entire 3-10 {\mu}m molecular fingerprint region. The system is
based on difference frequency generation in a GaSe crystal pumped by a 151 MHz
Yb:fiber frequency comb. The process was seeded with Raman shifted solitons
generated in a highly nonlinear suspended-core fiber with the same source.
Average powers up to 1.5 mW were achieved at 4.7 {\mu}m wavelength.
| arxiv topic:physics.optics |
arxiv_dataset-32791203.2541 | On the Hodge-Newton filtration for p-divisible groups with additional
structures
math.NT
We prove that, for a $p$-divisible group with additional structures over a
complete valuation ring of rank one $O_K$ with mixed characteristic $(0,p)$, if
the Newton polygon and the Hodge polygon of its special fiber possess a non
trivial contact point, which is a break point for the Newton polygon, then it
admits a "Hodge-Newton filtration" over $O_K$. The proof is based on the
theories of Harder-Narasimhan filtration of finite flat group schemes and
admissible filtered isocrystals. We then apply this result to the study of some
larger class of Rapoport-Zink spaces and Shimura varieties than those studied
previously by Mantovan, and confirm some new cases of Harris's conjecture.
| arxiv topic:math.NT |
arxiv_dataset-32801203.2641 | Internal Relativity
gr-qc
General relativity differs from other forces in nature in that it can be made
to disappear locally. This is the essence of the equivalence principle. In
general relativity the equivalence principle is implemented using differential
geometry. The connection that comes from a metric is used to glue together the
different gravity-free Minkowski spaces. In this article we argue that there is
another way to implement the equivalence principle. In this new way it is not
different Minkowski spaces that are connected but different vacua of an
underlying solid-state like model. One advantage of this approach to gravity is
that one can start with a quantum mechanical model so that the question of how
to arrive at a quantum theory of gravity does not arise. We show how the
gravitational constant can be calculated in this setup.
| arxiv topic:gr-qc |
arxiv_dataset-32811203.2741 | On (non-)local-connectivity of some Julia sets
math.DS math.CV
This article deals with the question of local connectivity of the Julia set
of polynomials and rational maps. It essentially presents conjectures and
questions.
| arxiv topic:math.DS math.CV |
arxiv_dataset-32821203.2841 | Trade-off between cost and goodput in wireless: Replacing transmitters
with coding
cs.NI
We study the cost of improving the goodput, or the useful data rate, to user
in a wireless network. We measure the cost in terms of number of base stations,
which is highly correlated to the energy cost as well as capital and
operational costs of a network provider.We show that increasing the available
bandwidth, or throughput, may not necessarily lead to increase in goodput,
particularly in lossy wireless networks in which TCP does not perform well. As
a result, much of the resources dedicated to the user may not translate to high
goodput, resulting in an inefficient use of the network resources. We show that
using protocols such as TCP/NC, which are more resilient to erasures and
failures in the network, may lead to a goodput commensurate the throughput
dedicated to each user. By increasing goodput, users' transactions are
completed faster; thus, the resources dedicated to these users can be released
to serve other requests or transactions. Consequently, we show that translating
efficiently throughput to goodput may bring forth better connection to users
while reducing the cost for the network providers.
| arxiv topic:cs.NI |
arxiv_dataset-32831203.2941 | GPU-based Monte Carlo dust radiative transfer scheme applied to AGN
astro-ph.CO
A three dimensional parallel Monte Carlo (MC) dust radiative transfer code is
presented. To overcome the huge computing time requirements of MC treatments,
the computational power of vectorized hardware is used, utilizing either
multi-core computer power or graphics processing units. The approach is a
self-consistent way to solve the radiative transfer equation in arbitrary dust
configurations. The code calculates the equilibrium temperatures of two
populations of large grains and stochastic heated polycyclic aromatic
hydrocarbons (PAH). Anisotropic scattering is treated applying the
Heney-Greenstein phase function. The spectral energy distribution (SED) of the
object is derived at low spatial resolution by a photon counting procedure and
at high spatial resolution by a vectorized ray-tracer. The latter allows
computation of high signal-to-noise images of the objects at any frequencies
and arbitrary viewing angles. We test the robustness of our approach against
other radiative transfer codes. The SED and dust temperatures of one and two
dimensional benchmarks are reproduced at high precision. We utilize the
Lucy-algorithm for the optical thin case where the Poisson noise is high, the
iteration free Bjorkman & Wood method to reduce the calculation time, and the
Fleck & Canfield diffusion approximation for extreme optical thick cells. The
code is applied to model the appearance of active galactic nuclei (AGN) at
optical and infrared wavelengths. The AGN torus is clumpy and includes fluffy
composite grains of various sizes made-up of silicates and carbon. The
dependence of the SED on the number of clumps in the torus and the viewing
angle is studied. The appearance of the 10 micron silicate features in
absorption or emission is discussed. The SED of the radio loud quasar 3C 249.1
is fit by the AGN model and a cirrus component to account for the far infrared
emission.
| arxiv topic:astro-ph.CO |
arxiv_dataset-32841203.3041 | Kaluza-Klein gauge and minimal integrable extension of OSp(4|6)/(SO(1,3)
x U(3)) sigma-model
hep-th
Basing upon experience from performing double-dimensional reduction of the
D=11 supermembrane on AdS_4 x S^7 background to Type IIA superstring on AdS_4 x
CP^3 we introduce Kaluza-Klein (partial) kappa-symmetry gauge as a vanishing
condition of the contribution to the D=11 supervielbein components tangent to
D=10 space-time proportional to the differential of the coordinate
parametrizing compact 11-th space-time dimension, that is identified with the
supermembrane world-volume compact dimension. For AdS_4 x S^7 supermembrane
Kaluza-Klein gauge removes half Grassmann coordinates associated with 8
space-time supersymmetries, broken by the AdS_4 x CP^3 superbackground, by
imposing D=3 (anti-)Majorana condition on them. The consideration relies on the
realization of osp(4|8) isometry superalgebra of the AdS_4 x S^7
superbackground as D=3 N=8 superconformal algebra. Requiring further vanishing
of the D=10 dilaton leaves in the sector of broken supersymmetries just two
Grassmann coordinates organized into D=3 (anti-)Majorana spinor that defines
minimal SL(2,R)-covariant extension of the OSp(4|6)/(SO(1,3)x U(3))
sigma-model. Among 4 possibilities of such a minimal extension we consider in
detail one, that corresponds to picking out D=3 Majorana coordinate related to
broken Poincare supersymmetry, and show that the AdS_4 x CP^3 superstring
equations of motion in this partial kappa-symmetry gauge are integrable. Also
the relation between the OSp(4|6)/(SO(1,3) x U(3)) sigma-model and the AdS_4 x
CP^3 superstring is revisited.
| arxiv topic:hep-th |
arxiv_dataset-32851203.3141 | BMSSM Higgses at 125 GeV
hep-ph
The BMSSM framework is an effective theory approach that encapsulates a
variety of extensions beyond the MSSM with which it shares the same field
content. The lightest Higgs mass can be much heavier than in the MSSM without
creating a tension with naturalness or requiring superheavy stops. The
phenomenology of the Higgs sector is at the same time much richer. We
critically review the properties of a Higgs with mass around 125GeV in this
model. In particular, we investigate how the rates in the important inclusive 2
photons channel, the 2 photons + 2 jets and the ZZ to 4 leptons (and/or WW) can
be enhanced or reduced compared to the standard model and what kind of
correlations between these rates are possible. We consider both a vanilla model
where stops have moderate masses and do not mix and a model with large mixing
and a light stop. We show that in both cases there are scenarios that lead to
enhancements in these rates at a mass of 125GeV corresponding either to the
lightest Higgs or the heaviest CP-even Higgs of the model. In all of these
scenarios we study the prospects of finding other signatures either of the
125GeV Higgs or those of the heavier Higgses. In most cases the $\oo{\tau}\tau$
channels are the most promising. Exclusion limits from the recent LHC Higgs
searches are folded in our analyses while the tantalising hints for a Higgs
signal at 125GeV are used as an example of how to constrain the BMSSM and/or
direct future searches.
| arxiv topic:hep-ph |
arxiv_dataset-32861203.3241 | Dynamics of periodic node states on a model of static networks with
repeated-averaging rules
physics.soc-ph cond-mat.stat-mech cs.SI
We introduce a simple model of static networks, where nodes are located on a
ring structure, and two accompanying dynamic rules of repeated averaging on
periodic node states. We assume nodes can interact with neighbors, and will add
long-range links randomly. The number of long-range links, E, controls
structures of these networks, and we show that there exist many types of fixed
points, when E is varied. When E is low, fixed points are mostly diverse
states, in which node states are diversely populated; on the other hand, when E
is high, fixed points tend to be dominated by converged states, in which node
states converge to one value. Numerically, we observe properties of fixed
points for various E's, and also estimate points of the transition from diverse
states to converged states for four different cases. This kind of simple
network models will help us understand how diversities that we encounter in
many systems of complex networks are sustained, even when mechanisms of
averaging are at work,and when they break down if more long-range connections
are added.
| arxiv topic:physics.soc-ph cond-mat.stat-mech cs.SI |
arxiv_dataset-32871203.3341 | A Comparison of the Embedding Method to Multi-Parametric Programming,
Mixed-Integer Programming, Gradient-Descent, and Hybrid Minimum Principle
Based Methods
math.OC cs.SY
In recent years, the embedding approach for solving switched optimal control
problems has been developed in a series of papers. However, the embedding
approach, which advantageously converts the hybrid optimal control problem to a
classical nonlinear optimization, has not been extensively compared to
alternative solution approaches. The goal of this paper is thus to compare the
embedding approach to multi-parametric programming, mixed-integer programming
(e.g., CPLEX), and gradient-descent based methods in the context of five
recently published examples: a spring-mass system, moving-target tracking for a
mobile robot, two-tank filling, DC-DC boost converter, and skid-steered
vehicle. A sixth example, an autonomous switched 11-region linear system, is
used to compare a hybrid minimum principle method and traditional numerical
programming. For a given performance index for each case, cost and solution
times are presented. It is shown that there are numerical advantages of the
embedding approach: lower performance index cost (except in some instances when
autonomous switches are present), generally faster solution time, and
convergence to a solution when other methods may fail. In addition, the
embedding method requires no ad hoc assumptions (e.g., predetermined mode
sequences) or specialized control models. Theoretical advantages of the
embedding approach over the other methods are also described: guaranteed
existence of a solution under mild conditions, convexity of the embedded hybrid
optimization problem (under the customary conditions on the performance index),
solvability with traditional techniques (e.g., sequential quadratic
programming) avoiding the combinatorial complexity in the number of
modes/discrete variables of mixed-integer programming, applicability to affine
nonlinear systems, and no need to explicitly assign discrete/mode variables to
autonomous switches.
| arxiv topic:math.OC cs.SY |
arxiv_dataset-32881203.3441 | Hydrodynamic interactions of colloidal spheres under shear flow
cond-mat.soft cond-mat.stat-mech
Particles that are immersed in a fluid exchange momentum via the fluid, hence
their Brownian motion is correlated. By means of multiparticle-collision
dynamics simulations we study the interactions between two colloidal beads in a
sheared fluid suspension. Recently, this topic has been addressed in
experiments on colloidal particles trapped by optical tweezers in a
microfluidic device [PRL, 103, 230602 (2009)] and theoretically by means of a
Langevin model [Eur. Phys. J E, 33, 313 (2010)]. Although we neglect the
rotational degrees of freedom of the colloids, and employ a very simple
coupling between the colloids and the flow field, we can reproduce the
experimental data and partly explain why it differs from theory.
| arxiv topic:cond-mat.soft cond-mat.stat-mech |
arxiv_dataset-32891203.3541 | A Tale of Dwarfs and Giants: Using a z=1.62 Cluster to Understand How
the Red Sequence Grew Over The Last 9.5 Billion Years
astro-ph.CO
We study the red sequence in a cluster of galaxies at z=1.62 and follow its
evolution over the intervening 9.5 Gyr to the present day. Using deep YJKs
imaging with the HAWK-I instrument on the VLT we identify a tight red sequence
and construct its rest-frame i-band luminosity function (LF). There is a marked
deficit of faint red galaxies in the cluster that causes a turnover in the LF.
We compare the red sequence LF to that for clusters at z<0.8 correcting the
luminosities for passive evolution. The shape of the cluster red sequence LF
does not evolve between z=1.62 and z=0.6 but at z<0.6 the faint population
builds up significantly. Meanwhile, between z=1.62 to 0.6 the inferred total
light on the red sequence grows by a factor of about 2 and the bright end of
the LF becomes more populated. We construct a simple model for red sequence
evolution that grows the red sequence in total luminosity and matches the
constant LF shape at z>0.6. In this model the cluster accretes blue galaxies
from the field that are then quenched and subsequently allowed to merge. We
find that 3--4 mergers among cluster galaxies during the 4 Gyr between z=1.62
and z=0.6 matches the observed luminosity function evolution between the two
redshifts. The inferred merger rate is consistent with other studies of this
cluster. Our result supports the picture that galaxy merging during the major
growth phase of massive clusters is an important process in shaping the red
sequence population at all luminosities.
| arxiv topic:astro-ph.CO |
arxiv_dataset-32901203.3641 | Inclusive J/psi production in pp collisions at sqrt(s) = 2.76 TeV
hep-ex
The ALICE Collaboration has measured inclusive J/psi production in pp
collisions at a center of mass energy sqrt(s)=2.76 TeV at the LHC. The results
presented in this Letter refer to the rapidity ranges |y|<0.9 and 2.5<y<4 and
have been obtained by measuring the electron and muon pair decay channels,
respectively. The integrated luminosities for the two channels are L^e_int=1.1
nb^-1 and L^mu_int=19.9 nb^-1, and the corresponding signal statistics are
N_J/psi^e+e-=59 +/- 14 and N_J/psi^mu+mu-=1364 +/- 53. We present
dsigma_J/psi/dy for the two rapidity regions under study and, for the forward-y
range, d^2sigma_J/psi/dydp_t in the transverse momentum domain 0<p_t<8 GeV/c.
The results are compared with previously published results at sqrt(s)=7 TeV and
with theoretical calculations.
| arxiv topic:hep-ex |
arxiv_dataset-32911203.3741 | A decomposition theorem for binary matroids with no prism minor
math.CO
The prism graph is the dual of the complete graph on five vertices with an
edge deleted, $K_5\backslash e$. In this paper we determine the class of binary
matroids with no prism minor. The motivation for this problem is the 1963
result by Dirac where he identified the simple 3-connected graphs with no minor
isomorphic to the prism graph. We prove that besides Dirac's infinite families
of graphs and four infinite families of non-regular matroids determined by
Oxley, there are only three possibilities for a matroid in this class: it is
isomorphic to the dual of the generalized parallel connection of $F_7$ with
itself across a triangle with an element of the triangle deleted; it's rank is
bounded by 5; or it admits a non-minimal exact 3-separation induced by the
3-separation in $P_9$. Since the prism graph has rank 5, the class has to
contain the binary projective geometries of rank 3 and 4, $F_7$ and $PG(3, 2)$,
respectively. We show that there is just one rank 5 extremal matroid in the
class. It has 17 elements and is an extension of $R_{10}$, the unique splitter
for regular matroids. As a corollary, we obtain Dillon, Mayhew, and Royle's
result identifying the binary internally 4-connected matroids with no prism
minor [5].
| arxiv topic:math.CO |
arxiv_dataset-32921203.3841 | Coupling between whistler waves and slow-mode solitary waves
physics.plasm-ph
The interplay between electron-scale and ion-scale phenomena is of general
interest for both laboratory and space plasma physics. In this paper we
investigate the linear coupling between whistler waves and slow magnetosonic
solitons through two-fluid numerical simulations. Whistler waves can be trapped
in the presence of inhomogeneous external fields such as a density hump or hole
where they can propagate for times much longer than their characteristic time
scale, as shown by laboratory experiments and space measurements. Space
measurements have detected whistler waves also in correspondence to magnetic
holes, i.e., to density humps with magnetic field minima extending on
ion-scales. This raises the interesting question of how ion-scale structures
can couple to whistler waves. Slow magnetosonic solitons share some of the main
features of a magnetic hole. Using the ducting properties of an inhomogeneous
plasma as a guide, we present a numerical study of whistler waves that are
trapped and transported inside propagating slow magnetosonic solitons.
| arxiv topic:physics.plasm-ph |
arxiv_dataset-32931203.3941 | On the Unlikeliness of Multi-Field Inflation: Bounded Random Potentials
and our Vacuum
hep-th astro-ph.CO
Based on random matrix theory, we compute the likelihood of saddles and
minima in a class of random potentials that are softly bounded from above and
below, as required for the validity of low energy effective theories. Imposing
this bound leads to a random mass matrix with non-zero mean of its entries. If
the dimensionality of field-space is large, inflation is rare, taking place
near a saddle point (if at all), since saddles are more likely than minima or
maxima for common values of the potential. Due to the boundedness of the
potential, the latter become more ubiquitous for rare low/large values
respectively. Based on the observation of a positive cosmological constant, we
conclude that the dimensionality of field-space after (and most likely during)
inflation has to be low if no anthropic arguments are invoked, since the
alternative, encountering a metastable deSitter vacuum by chance, is extremely
unlikely.
| arxiv topic:hep-th astro-ph.CO |
arxiv_dataset-32941203.4041 | When the Cut Condition is Enough: A Complete Characterization for
Multiflow Problems in Series-Parallel Networks
cs.DM cs.DS
Let $G=(V,E)$ be a supply graph and $H=(V,F)$ a demand graph defined on the
same set of vertices. An assignment of capacities to the edges of $G$ and
demands to the edges of $H$ is said to satisfy the \emph{cut condition} if for
any cut in the graph, the total demand crossing the cut is no more than the
total capacity crossing it. The pair $(G,H)$ is called \emph{cut-sufficient} if
for any assignment of capacities and demands that satisfy the cut condition,
there is a multiflow routing the demands defined on $H$ within the network with
capacities defined on $G$. We prove a previous conjecture, which states that
when the supply graph $G$ is series-parallel, the pair $(G,H)$ is
cut-sufficient if and only if $(G,H)$ does not contain an \emph{odd spindle} as
a minor; that is, if it is impossible to contract edges of $G$ and delete edges
of $G$ and $H$ so that $G$ becomes the complete bipartite graph $K_{2,p}$, with
$p\geq 3$ odd, and $H$ is composed of a cycle connecting the $p$ vertices of
degree 2, and an edge connecting the two vertices of degree $p$. We further
prove that if the instance is \emph{Eulerian} --- that is, the demands and
capacities are integers and the total of demands and capacities incident to
each vertex is even --- then the multiflow problem has an integral solution. We
provide a polynomial-time algorithm to find an integral solution in this case.
In order to prove these results, we formulate properties of tight cuts (cuts
for which the cut condition inequality is tight) in cut-sufficient pairs. We
believe these properties might be useful in extending our results to planar
graphs.
| arxiv topic:cs.DM cs.DS |
arxiv_dataset-32951203.4141 | Counting systems and the First Hilbert problem
math.GM
The First Hilbert problem is studied in this paper by applying two
instruments: a new methodology distinguishing between mathematical objects and
mathematical languages used to describe these objects; and a new numeral system
allowing one to express different infinite numbers and to use these numbers for
measuring infinite sets. Several counting systems are taken into consideration.
It is emphasized in the paper that different mathematical languages can
describe mathematical objects (in particular, sets and the number of their
elements) with different accuracies. The traditional and the new approaches are
compared and discussed.
| arxiv topic:math.GM |
arxiv_dataset-32961203.4241 | Anderson Localization in Disordered Vibrating Rods
nlin.CD cond-mat.dis-nn cond-mat.mes-hall quant-ph
We study, both experimentally and numerically, the Anderson localization
phenomenon in torsional waves of a disordered elastic rod, which consists of a
cylinder with randomly spaced notches. We find that the normal-mode wave
amplitudes are exponentially localized as occurs in disordered solids. The
localization length is measured using these wave amplitudes and it is shown to
decrease as a function of frequency. The normal-mode spectrum is also measured
as well as computed, so its level statistics can be analyzed. Fitting the
nearest-neighbor spacing distribution a level repulsion parameter is defined
that also varies with frequency. The localization length can then be expressed
as a function of the repulsion parameter. There exists a range in which the
localization length is a linear function of the repulsion parameter, which is
consistent with Random Matrix Theory. However, at low values of the repulsion
parameter the linear dependence does not hold.
| arxiv topic:nlin.CD cond-mat.dis-nn cond-mat.mes-hall quant-ph |
arxiv_dataset-32971203.4341 | Rydberg crystallization detection by statistical means
cond-mat.quant-gas physics.atom-ph quant-ph
We investigate an ensemble of atoms which can be excited into a Rydberg
state. Using a disordered quantum Ising model, we perform a numerical
simulation of the experimental procedure and calculate the probability
distribution function $P(M)$ to create a certain number of Rydberg atoms $M$,
as well as their pair correlation function. Using the latter, we identify the
critical interaction strength above which the system undergoes a phase
transition to a Rydberg crystal. We then show that this phase transition can be
detected using $P(M)$ alone.
| arxiv topic:cond-mat.quant-gas physics.atom-ph quant-ph |
arxiv_dataset-32981203.4441 | Novel Bose-Einstein Interference in the Passage of a Fast Particle in a
Dense Medium
hep-ph nucl-th quant-ph
When an energetic particle collides coherently with many medium particles at
high energies, the Bose-Einstein symmetry with respect to the interchange of
the exchanged virtual bosons leads to a destructive interference of the Feynman
amplitudes in most regions of the phase space but a constructive interference
in some other regions of the phase space. As a consequence, the recoiling
medium particles have a tendency to come out collectively along the direction
of the incident fast particle, each carrying a substantial fraction of the
incident longitudinal momentum. Such an interference appearing as collective
recoils of scatterers along the incident particle direction may have been
observed in angular correlations of hadrons associated with a high-$p_T$
trigger in high-energy AuAu collisions at RHIC.
| arxiv topic:hep-ph nucl-th quant-ph |
arxiv_dataset-32991203.4541 | Entangled symmetries explain without QCD dynamics CP violation in
neutral B to Kpi decays; not in charged B decays Unexpected isospin relations
in charged and neutral decays,
hep-ph
Simple flavor symmetry argument without QCD dynamics shows why CP violation
observed in neutral $B$ to $K\pi$ decays is absent in charged B decays where
tree diagram final state has two $u$ quarks satisfying Pauli principle.
Entanglement preserves short range symmetry correlations after separation into
two mesons. Pauli principle and symmetries require totally flavor-symmetric
tree diagram final state. $\pi \pi$ isospin state with I=2 already is flavor
symmetric and suffers no symmetry constraint. Strange flavor-symmetric state
with V spin V=2 is linear combination of $K\pi$ and $K \eta$ with probability
only (1/4) for $K\pi$. Tree diagram suppression by factor 4 not present in
neutral decays explains negligible tree-penguin interference and CP violation
in charged decays. Detailed full symmetry analysis shows constraints from
space-inversion, charge conjugation, Pauli antisymmetrization and flavor
symmetry. Two antiquarks produced at same space point by tree diagram have even
parity. Even parity final state requires even parity, even space symmetry and
color-spin antisymmetry for two $u$ quarks. Color-singlet spin-singlet final
state requires color-spin antisymmetry and therefore flavor symmetry for
two-antiquark wave function. Flavor symmetric $\bar u \bar d$ and $\bar u \bar
s$ antiquark pairs have isospin I=1 and V-spin V =1. Generalized charge
conjugation invariance requires I=2 for $\pi\pi$ tree diagram and V = 2 for
$K\pi$. Penguin decays give I = 1/2 final state and no CP violation.
Experiments confirm surprising predictions from tree suppression factor not
noted in previous analyzes. I=1/2 violations seen only in relation between
charged and neutral decays together with no I=3/2 components in each individual
decay. Common treatments using $\pi \pi$ data fail to fit $K\pi$ data.
| arxiv topic:hep-ph |
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