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arxiv_dataset-44001306.5216 | Modification to Darcy model for high pressure and high velocity
applications and associated mixed finite element formulations
cs.NA
The Darcy model is based on a plethora of assumptions. One of the most
important assumptions is that the Darcy model assumes the drag coefficient to
be constant. However, there is irrefutable experimental evidence that
viscosities of organic liquids and carbon-dioxide depend on the pressure.
Experiments have also shown that the drag varies nonlinearly with respect to
the velocity at high flow rates. In important technological applications like
enhanced oil recovery and geological carbon-dioxide sequestration, one
encounters both high pressures and high flow rates. It should be emphasized
that flow characteristics and pressure variation under varying drag are both
quantitatively and qualitatively different from that of constant drag.
Motivated by experimental evidence, we consider the drag coefficient to depend
on both the pressure and velocity. We consider two major modifications to the
Darcy model based on the Barus formula and Forchheimer approximation. The
proposed modifications to the Darcy model result in nonlinear partial
differential equations, which are not amenable to analytical solutions. To this
end, we present mixed finite element formulations based on least-squares
formalism and variational multiscale formalism for the resulting governing
equations. The proposed modifications to the Darcy model and its associated
finite element formulations are used to solve realistic problems with relevance
to enhanced oil recovery. We also study the competition between the nonlinear
dependence of drag on the velocity and the dependence of viscosity on the
pressure. To the best of the authors' knowledge such a systematic study has not
been performed.
| arxiv topic:cs.NA |
arxiv_dataset-44011306.5316 | Hamilton cycles in almost distance-hereditary graphs
math.CO
Let $G$ be a graph on $n\geq 3$ vertices. A graph $G$ is almost
distance-hereditary if each connected induced subgraph $H$ of $G$ has the
property $d_{H}(x,y)\leq d_{G}(x,y)+1$ for any pair of vertices $x,y\in V(H)$.
A graph $G$ is called 1-heavy (2-heavy) if at least one (two) of the end
vertices of each induced subgraph of $G$ isomorphic to $K_{1,3}$ (a claw) has
(have) degree at least $n/2$, and called claw-heavy if each claw of $G$ has a
pair of end vertices with degree sum at least $n$. Thus every 2-heavy graph is
claw-heavy. In this paper we prove the following two results: (1) Every
2-connected, claw-heavy and almost distance-hereditary graph is Hamiltonian.
(2) Every 3-connected, 1-heavy and almost distance-hereditary graph is
Hamiltonian. In particular, the first result improves a previous theorem of
Feng and Guo. Both results are sharp in some sense.
| arxiv topic:math.CO |
arxiv_dataset-44021306.5416 | Pairing Effect on Spectral Statistics of Even and Odd Mass Nuclei
nucl-th
The interplay of pairing is explored for the spectral statistics of nuclear
systems with emphasis on the nearest neighbor spacing distributions by
employing the kernel density and maximum likelihood estimation techniques.
Different sequences prepared by all the available empirical data for low-lying
energy levels of even and odd-mass nuclei in the 34 < A < 206 mass region. A
deviation to more regular dynamics is apparent for even-mass nuclei in compare
to odd-mass ones, and there are suggestions of effects due to unclosed proton
shells on more chaotic dynamics.
| arxiv topic:nucl-th |
arxiv_dataset-44031306.5516 | Some Generalization of Hadamard's type Inequalities through
Differentiability for s-Convex Function and their Applications
math.FA math.CA
In this paper, a general form of integral inequalities of Hermite-Hadamard's
type through differentiability for s-Convex function in second sense and whose
all derivatives are absolutely continuous are established. The generalized
integral inequalities contributes some better estimates than some already
presented. The inequalities are then applied to numerical integration and some
special means.
| arxiv topic:math.FA math.CA |
arxiv_dataset-44041306.5616 | Approximate controllability for a 2D Grushin equation with potential
having an internal singularity
math.OC math.AP
This paper is dedicated to approximate controllability for Grushin equation
on the rectangle $(x,y) \in (-1,1) \times (0,1)$ with an inverse square
potential. This model corresponds to the heat equation for the Laplace-Beltrami
operator associated to the Grushin metric on $\mathbb{R}^2$, studied by Boscain
and Laurent. The operator is both degenerate and singular on the line $\{ x=0
\}$.
The approximate controllability is studied through unique continuation of the
adjoint system. For the range of singularity under study, approximate
controllability is proved to hold whatever the degeneracy is.
Due to the internal inverse square singularity, a key point in this work is
the study of well-posedness. An extension of the singular operator is designed
imposing suitable transmission conditions through the singularity.
Then, unique continuation relies on the Fourier decomposition of the 2D
solution in one variable and Carleman estimates for the 1D heat equation solved
by the Fourier components. The Carleman estimate uses a suitable Hardy
inequality.
| arxiv topic:math.OC math.AP |
arxiv_dataset-44051306.5716 | On the global existence solution for a chemotaxis model
math.AP math.FA
This paper has been withdrawn by the authors. We consider the
attraction-repulsion chemotaxis system (3 complicated PDEs system) under
homogeneous Neumann boundary conditions in a bounded domain {\Omega} with
smooth boundary, then the classical solutions to the system are
uniformly-in-time bounded. After the local existence and uniqueness of
solutions was proved, some priory estimates and proves will be established for
the global existence of solutions (see the complete abstract in the PDF version
of paper).
| arxiv topic:math.AP math.FA |
arxiv_dataset-44061306.5816 | Problem of Time: Facets and Machian Strategy
gr-qc
The Problem of Time is that `time' in each of ordinary quantum theory and
general relativity are mutually incompatible notions. This causes difficulties
in trying to put these two theories together to form a theory of Quantum
Gravity. The Problem of Time has 8 facets in canonical approaches. I clarify
that all but one of these facets already occur at the classical level, and
reconceptualize and re-name some of these facets as follows.The Frozen
Formalism Problem becomes Temporal Relationalism, the Thin Sandwich Problem
becomes Configurational Relationalism, via the notion of Best Matching. The
Problem of Observables becomes the Problem of Beables, and the Functional
Evolution Problem becomes the Constraint Closure Problem. I also outline how
each of the Global and Multiple-Choice Problems of Time have their own
plurality of facets.
This article additionally contains a local resolution to the Problem of Time
at the conceptual level and which is actually realizable for the relational
triangle and minisuperspace models. This resolution is, moreover, Machian, and
has three levels: classical, semiclassical and a combined
semiclassical-histories-timeless records scheme. I end by delineating the
current frontiers of this program toward resolution of the Problem of Time in
the cases of full GR and of slightly inhomogeneous cosmology.
| arxiv topic:gr-qc |
arxiv_dataset-44071306.5916 | Jahn-Teller, polarity and insulator-to-metal transition in BiMnO3 at
high pressure
cond-mat.mtrl-sci
The interaction of coexisting structural instabilities in multiferroic
materials gives rise to intriguing coupling phenomena and extraordinarily rich
phase diagrams, both in bulk materials and strained thin films. Here we
investigate the multiferroic BiMnO3 with its peculiar 6s2 electrons and four
interacting mechanisms: electric polarity, octahedra tilts, magnetism, and
cooperative Jahn-Teller distortion. We have probed structural transitions under
high pressure by synchrotron x-ray diffraction and Raman spectroscopy up to 60
GPa. We show that BiMnO3 displays under pressure a rich sequence of five phases
with a great variety of structures and properties, including a metallic phase
above 53 GPa and, between 37 and 53 GPa, a strongly elongated monoclinic phase
that allows ferroelectricity, which contradicts the traditional expectation
that ferroelectricity vanishes under pressure. Between 7 and 37 GPa, the Pnma
structure remains remarkably stable but shows a reduction of the Jahn-Teller
distortion in a way that differs from the behavior observed in the archetypal
orthorhombic Jahn-Teller distorted perovskite LaMnO3.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-44081306.6016 | Triaxial Cosmological Haloes and the Disc of Satellites
astro-ph.CO astro-ph.GA
We construct simple triaxial generalisations of Navarro-Frenk-White haloes.
The models have elementary gravitational potentials, together with a density
that is cusped like 1/r at small radii and falls off like 1/r^3 at large radii.
The ellipticity varies with radius in a manner that can be tailored to the
user's specification. The closed periodic orbits in the planes perpendicular to
the short and long axes of the model are well-described by epicyclic theory,
and can be used as building blocks for long-lived discs. As an application, we
carry out the simulations of thin discs of satellites in triaxial dark halo
potentials. This is motivated by the recent claims of an extended, thin disc of
satellites around the M31 galaxy with a vertical rms scatter of ~12 kpc and a
radial extent of ~ 300 kpc (Ibata et al. 2013). We show that a thin satellite
disc can persist over cosmological times if and only if it lies in the planes
perpendicular to the long or short axis of a triaxial halo, or in the
equatorial or polar planes of a spheroidal halo. In any other orientation, then
the disc thickness doubles on ~5 Gyr timescales and so must have been born with
an implausibly small vertical scaleheight.
| arxiv topic:astro-ph.CO astro-ph.GA |
arxiv_dataset-44091306.6116 | Distributed Estimation and Detection with Bounded Transmissions over
Gaussian Multiple Access Channels
cs.DC cs.IT math.IT
A distributed inference scheme which uses bounded transmission functions over
a Gaussian multiple access channel is considered. When the sensor measurements
are decreasingly reliable as a function of the sensor index, the conditions on
the transmission functions under which consistent estimation and reliable
detection are possible is characterized. For the distributed estimation
problem, an estimation scheme that uses bounded transmission functions is
proved to be strongly consistent provided that the variance of the noise
samples are bounded and that the transmission function is one-to-one. The
proposed estimation scheme is compared with the amplify-and-forward technique
and its robustness to impulsive sensing noise distributions is highlighted. In
contrast to amplify-and-forward schemes, it is also shown that bounded
transmissions suffer from inconsistent estimates if the sensing noise variance
goes to infinity. For the distributed detection problem, similar results are
obtained by studying the deflection coefficient. Simulations corroborate our
analytical results.
| arxiv topic:cs.DC cs.IT math.IT |
arxiv_dataset-44101306.6216 | Null Killing vectors and geometry of null strings in Einstein spaces
gr-qc
Einstein complex spacetimes admitting null Killing or null homothetic Killing
vectors are studied. These vectors define totally null and geodesic 2-surfaces
called the null strings or twistor surfaces. Geometric properties of these null
strings are discussed. It is shown, that spaces considered are hyperheavenly
spaces (HH-spaces) or, if one of the parts of the Weyl tensor vanishes,
heavenly spaces (H-spaces). The explicit complex metrics admitting null Killing
vectors are found. Some Lorentzian and ultrahyperbolic slices of these metrics
are discussed.
| arxiv topic:gr-qc |
arxiv_dataset-44111306.6316 | An Effect System for Algebraic Effects and Handlers
cs.PL cs.LO
We present an effect system for core Eff, a simplified variant of Eff, which
is an ML-style programming language with first-class algebraic effects and
handlers. We define an expressive effect system and prove safety of operational
semantics with respect to it. Then we give a domain-theoretic denotational
semantics of core Eff, using Pitts's theory of minimal invariant relations, and
prove it adequate. We use this fact to develop tools for finding useful
contextual equivalences, including an induction principle. To demonstrate their
usefulness, we use these tools to derive the usual equations for mutable state,
including a general commutativity law for computations using non-interfering
references. We have formalized the effect system, the operational semantics,
and the safety theorem in Twelf.
| arxiv topic:cs.PL cs.LO |
arxiv_dataset-44121306.6416 | The optical counterpart to the X-ray transient IGR J18245-2452 in the
globular cluster M28
astro-ph.SR astro-ph.HE
We report on the identification of the optical counterpart to the recently
detected INTEGRAL transient IGR J18245-2452 in the Galactic globular cluster
M28. From the analysis of a multi epoch HST dataset we have identified a
strongly variable star positionally coincident with the radio and Chandra X-ray
sources associated to the INTEGRAL transient. The star has been detected during
both a quiescent and an outburst state. In the former case it appears as a
faint, unperturbed main sequence star, while in the latter state it is about
two magnitudes brighter and slightly bluer than main sequence stars. We also
detected Halpha excess during the outburst state, suggestive of active
accretion processes by the neutron star.
| arxiv topic:astro-ph.SR astro-ph.HE |
arxiv_dataset-44131306.6516 | Electron acceleration by coherent laser pulse echelons in periodic
plasma structures
physics.plasm-ph physics.acc-ph
We consider a possibilty to use an echelon of mutually coherent laser pulses
generated by the emerging CAN (Coherent Amplification Network) technology for
direct particle acceleration in periodic plasma structures. The plasma
structure survives a single shot only. However, due to it's simplicity and
projected very low production costs, the structure can be replaced for every
laser shot at a kiloherz repetition rate. We discuss resonant and free
streaming configurations. The resonant plasma structures can trap energy of
longer laser pulses but are limited to moderate laser intensities of about
10^{14}\,{\rm W/cm^{2}} and are very sensitive to the structure quality. The
free streaming configurations can survive laser intensities above 10^{18}\,{\rm
W/cm^{2}} for several tens of femtoseconds so that sustained accelerating rates
well above {\rm TeV/m} are feasible. In our full electromagnetic relativistic
particle-in-cell (PIC) simulations we show a test electron bunch gaining up to
120\,{\rm GeV} over a distance of 5.3\,{\rm cm} only.
| arxiv topic:physics.plasm-ph physics.acc-ph |
arxiv_dataset-44141306.6616 | $\Psi$ and $\Upsilon$ Production In pp Collisions at 7.0 TeV
hep-ph
This is an extension of recent studies [arXiv:1207.3296] for $\Upsilon(nS)$
and $\Psi(1S,2S)$ production at the LHC in pp collisions, $\sqrt{s}$=7.0 GeV,
with the ALICE detector.
| arxiv topic:hep-ph |
arxiv_dataset-44151306.6716 | Earliest Stages of Protocluster Formation: Substructure and Kinematics
of Starless Cores in Orion
astro-ph.GA
We study the structure and kinematics of nine 0.1 pc-scale cores in Orion
with the IRAM 30-m telescope and at higher resolution eight of the cores with
CARMA, using CS(2-1) as the main tracer. The single-dish moment zero maps of
the starless cores show single structures with central column densities ranging
from 7 to 42 times 10^23 cm^-2 and LTE masses from 20 solar masses to 154 solar
masses. However, at the higher CARMA resolution (5 arcsec), all of the cores
except one fragment into 3 - 5 components. The number of fragments is small
compared to that found in some turbulent fragmentation models, although
inclusion of magnetic fields may reduce the predicted fragment number and
improve the model agreement. This result demonstrates that fragmentation from
parsec-scale molecular clouds to sub-parsec cores continues to take place
inside the starless cores. The starless cores and their fragments are embedded
in larger filamentary structures, which likely played a role in the core
formation and fragmentation. Most cores show clear velocity gradients, with
magnitudes ranging from 1.7 to 14.3 km/s/pc. We modeled one of them in detail,
and found that its spectra are best explained by a converging flow along a
filament toward the core center; the gradients in other cores may be modeled
similarly. We infer a mass inflow rate of ~ 2 x 10^{-3} Msolar/yr, which is in
principle high enough to overcome radiation pressure and allow for massive star
formation. However, the core contains multiple fragments, and it is unclear
whether the rapid inflow would feed the growth of primarily a single massive
star or a cluster of lower mass objects. We conclude that fast, supersonic
converging flow along filaments play an important role in massive star and
cluster formation.
| arxiv topic:astro-ph.GA |
arxiv_dataset-44161306.6816 | Entanglement of four qubit systems: a geometric atlas with polynomial
compass I (the finite world)
math-ph math.AG math.MP math.RT quant-ph
We investigate the geometry of the four qubit systems by means of algebraic
geometry and invariant theory, which allows us to interpret certain entangled
states as algebraic varieties. More precisely we describe the nullcone, i.e.,
the set of states annihilated by all invariant polynomials, and also the so
called third secant variety, which can be interpreted as the generalization of
GHZ-states for more than three qubits. All our geometric descriptions go along
with algorithms which allow us to identify any given state in the nullcone or
in the third secant variety as a point of one of the 47 varieties described in
the paper. These 47 varieties correspond to 47 non-equivalent entanglement
patterns, which reduce to 15 different classes if we allow permutations of the
qubits.
| arxiv topic:math-ph math.AG math.MP math.RT quant-ph |
arxiv_dataset-44171306.6916 | The Linear US-uP Relation in Shock-Wave Physics
cond-mat.mtrl-sci physics.chem-ph
A linear relation between shock velocity US and particle velocity UP is often
regarded as the "typical" or "standard" material response in the shock-wave
literature. It has even been proposed that this linearity follows from some
kind of universal equation of state (EOS) principle. This report presents a
theoretical analysis of this issue and a survey of the Hugoniot data for all
the elements. It demonstrates that linearity follows from the fact that US-UP
plots are rather insensitive to material properties, not from any universal
EOS. The effects of pressure and material properties on the shock response are
more easily seen and analyzed by plotting UF = US - UP as a function of UP. The
data survey shows that linear behavior is only observed in 20% of all the
elements and is not at all universal.
| arxiv topic:cond-mat.mtrl-sci physics.chem-ph |
arxiv_dataset-44181307.0072 | Log Analysis Techniques using Clustering in Network Forensics
cs.CY cs.CR
Internet crimes are now increasing. In a row with many crimes using
information technology, in particular those using Internet, some crimes are
often carried out in the form of attacks that occur within a particular agency
or institution. To be able to find and identify the types of attacks, requires
a long process that requires time, human resources and utilization of
information technology to solve these problems. The process of identifying
attacks that happened also needs the support of both hardware and software as
well. The attack happened in the Internet network can generally be stored in a
log file that has a specific data format. Clustering technique is one of
methods that can be used to facilitate the identification process. Having
grouped the data log file using K-means clustering technique, then the data is
grouped into three categories of attack, and will be continued with the
forensic process that can later be known to the source and target of attacks
that exist in the network. It is concluded that the framework proposed can help
the investigator in the trial process.
| arxiv topic:cs.CY cs.CR |
arxiv_dataset-44191307.0172 | Observing remnants by fermions' tunneling
gr-qc hep-th
The standard Hawking formula predicts the complete evaporation of black
holes. In this paper, we introduce effects of quantum gravity into fermions'
tunneling from Reissner-Nordstrom and Kerr black holes. The quantum gravity
effects slow down the increase of Hawking temperatures. This property naturally
leads to a residue mass in black hole evaporation. The corrected temperatures
are affected by the quantum numbers of emitted fermions. Meanwhile, the
temperature of the Kerr black hole is a function of $\theta$ due to the
rotation.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-44201307.0272 | Informational correlation between two parties of a quantum system: short
spin-1/2 chains with XY Hamiltonian
quant-ph
We introduce the informational correlation $E^{AB}$ between two interacting
quantum subsystems $A$ and $B$ of a quantum system as the number of arbitrary
parameters $\varphi_i$ of a unitary transformation $U^A$ (locally performed on
the subsystem $A$) which may be detected in the subsystem $B$ by the local
measurements. This quantity indicates whether the state of the subsystem $B$
may be effected by means of the unitary transformation applied to the subsystem
$A$. Emphasize that $E^{AB}\neq E^{BA}$ in general. The informational
correlations in systems with tensor product initial states are studied in more
details. In particular, it is shown that the informational correlation may be
changed by the local unitary transformations of the subsystem $B$. However,
there is some non-reducible part of $E^{AB}(t)$ which may not be decreased by
any unitary transformation of the subsystem $B$ at a fixed time instant $t$.
Two examples of the informational correlations between two parties of the four
node spin-1/2 chain are studied.
| arxiv topic:quant-ph |
arxiv_dataset-44211307.0372 | Anderson localization of a Majorana fermion
cond-mat.mes-hall cond-mat.supr-con
Isolated Majorana fermion states can be produced at the boundary of a
topological superconductor in a quasi-one-dimensional geometry. If such a
superconductor is connected to a disordered quantum wire, the Majorana fermion
is spread into the wire, subject to Anderson localization. We study this effect
in the limit of a thick wire with broken time-reversal and spin-rotational
symmetries. With the use of a supersymmetric nonlinear sigma model, we
calculate the average local density of states in the wire as a function of
energy and of the distance from the interface with the superconductor. Our
results may be qualitatively explained by the repulsion of states from the
Majorana level and by Mott hybridization of localized states.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con |
arxiv_dataset-44221307.0472 | Metal-Rich PNe in the Outer Reaches of M31
astro-ph.GA
Spectroscopic data of two relatively [O III]-luminous-PNe have been obtained
with the 10.4-m Gran Telescopio Canarias. M174 and M2496 are each ~1 degree
from the center of M31 along opposite sides of its minor axis. The ensemble of
these two distant PNe plus 16 similarly luminous outer-disk PNe published
earlier (Kwitter et al. 2012 & 2013) forms a homogeneous group in luminosity,
metal content, progenitor mass, age, and kinematics. The main factual findings
of our work are: (1) O/H (and other low-mass alpha elements and their ratios to
O) is uniformly solar-like in all 18 PNe <12+log(O/H)> = 8.62 +/- 0.14); (2)
the general sky distribution and kinematics of the ensemble much more closely
resemble the rotation pattern of the classical disk of M31 than its halo or
bulge; (3) the O/H gradient is surprisingly flat beyond R_g ~30 kpc, and may be
flat throughout the entire range of R_g covered in the full study. The PNe are
too metal-rich to be bona fide members of M31's disk or halo, and (4) the
abundance patterns of the sample are distinct from those in the spiral galaxies
M33, M81, and NGC 300. Using standard PN age diagnostic methods (which are
readily challengeable) we suggest that all of the PNe formed -2 GY ago in a
starburst of metal-rich ISM that followed an M31-M33 encounter about 3 GY ago.
We review supporting evidence from stellar studies. Other more prosaic
explanations, such as dwarf galaxy assimilation, are unlikely.
| arxiv topic:astro-ph.GA |
arxiv_dataset-44231307.0572 | On the time scales in the approach to equilibrium of macroscopic quantum
systems
cond-mat.stat-mech quant-ph
We prove two theorems concerning the time evolution in general isolated
quantum systems. The theorems are relevant to the issue of the time scale in
the approach to equilibrium. The first theorem shows that there can be
pathological situations in which the relaxation takes an extraordinarily long
time, while the second theorem shows that one can always choose an equilibrium
subspace the relaxation to which requires only a short time for any initial
state.
| arxiv topic:cond-mat.stat-mech quant-ph |
arxiv_dataset-44241307.0672 | Coxeter groups and their quotients arising from cluster algebras
math.CO math.GR
In a recent paper, Barot and Marsh presented an explicit construction of
presentation of a finite Weyl group by any seed of corresponding cluster
algebra, i.e. by any diagram mutation-equivalent to an orientation of a Dynkin
diagram with given Weyl group. Extending their construction to the affine case,
we obtain presentations for all affine Coxeter groups. Furthermore, we
generalize the construction to the settings of diagrams arising from
unpunctured triangulated surfaces and orbifolds, which leads to presentations
of corresponding groups as quotients of numerous distinct Coxeter groups.
| arxiv topic:math.CO math.GR |
arxiv_dataset-44251307.0772 | How to Build an RSS Feed using ASP
cs.OH
RSS is a XML based format. The Current popular version of RSS is RSS version
2.0. The purpose of adding an RSS feed to your site is to show if anything new
is added to the site. For example, if a new article or blog or news item is
added to your site that should automatically appear in the RSS feed so that the
visitors/ RSS readers will automatically get updated about this new addition.
The RSS feed is also called RSS channel.
There are two main elements of the RSS XML file, one is the header or channel
element that describes the details about the site/feeder and other is the body
or item element that describes the consists of individual articles/entries
updated in the site. As the format of the RSS feed file is pretty simple, it
can be coded in any language, ASP, PHP or anything of that sort. We will build
an RSS feeder using classical ASP (Active Server Pages) code in this article.
| arxiv topic:cs.OH |
arxiv_dataset-44261307.0872 | Maximization of recursive utilities under convex portfolio constraints
math.PR q-fin.PM
We study a robust maximization problem from terminal wealth and consumption
under a convex constraints on the portfolio. We state the existence and the
uniqueness of the consumption-investment strategy by studying the associated
quadratic backward stochastic differential equation (BSDE in short). We
characterize the optimal control by using the duality method and deriving a
dynamic maximum principle.
| arxiv topic:math.PR q-fin.PM |
arxiv_dataset-44271307.0972 | From complete to partial flags in geometric extension algebras
math.RT
A geometric extension algebra is an extension algebra of a semi-simple
perverse sheaf (allowing shifts), e.g. a push-forward of the constant sheaf
under a projective map. Particular nice situations arise for collapsings of
homogeneous vector bundle over homogeneous spaces. In this paper, we study the
relationship between partial flag and complete flag cases. Our main result is
that the locally finite modules over the geometric extension algebras are
related by a recollement. As examples, we investigate parabolic affine nil
Hecke algebras, geometric extension algebras associated to parabolic Springer
maps and an example of Reineke of a parabolic quiver-graded Hecke algebra.
| arxiv topic:math.RT |
arxiv_dataset-44281307.1072 | Suppression of the S-wave production of (3/2)^+ + (1/2)^- heavy meson
pairs in e^+e^- annihilation
hep-ph hep-ex
The heavy meson-antimeson pairs, where one is an excited $\bigl ({3 \over 2}
\bigr) ^+ $ meson and the other is a ground state $\bigl ({1 \over 2} \bigr)
^-$ meson, namely the pairs ($D_1(2420) \bar D$ + c.c.), ($D_1(2420) \bar D^*$
+ c.c.), ($D_2(2460) \bar D^*$ + c.c.) in the charm sector and ($B_1(5721) \bar
B$ + c.c.), ($B_1(5721) \bar B^*$ + c.c.), ($B_2(5747) \bar B^*$ + c.c.) in the
bottom sector, are allowed, by the quantum numbers, to be produced in the $S$
wave in $e^+e^-$ annihilation. We show, however, that such $S$-wave production
is forbidden by the heavy quark spin symmetry. Thus the yield of the considered
meson pairs in $e^+e^-$ annihilation should be significantly suppressed near
the respective thresholds. In our view, this substantially weakens the
arguments for considering the Y(4260) charmonium-like resonance as a $D_1 \bar
D$ molecular state.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-44291307.1172 | Large Spin Pumping from Epitaxial Y3Fe5O12 Thin Films to Pt and W Layers
cond-mat.mtrl-sci
Epitaxial Y3Fe5O12 thin films have been deposited by off-axis sputtering,
which exhibit excellent crystalline quality, enabling observation of large spin
pumping signals in Pt/Y3Fe5O12 and W/Y3Fe5O12 bilayers driven by cavity
ferromagnetic resonance. The inverse spin Hall voltages reach 2.10 mV and -5.26
mV in 5-mm long Pt/Y3Fe5O12 and W/Y3Fe5O12 bilayers, respectively, excited by a
radio-frequency magnetic field of 0.3 Oe. From the ferromagnetic resonance
linewidth broadening, the interfacial spin mixing conductance of 4.56E14
{\Omega}-1m-2 and 2.30E14 {\Omega}-1m-2 are obtained for Pt/Y3Fe5O12 and
W/Y3Fe5O12 bilayers, respectively.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-44301307.1272 | t3evol - Numerical Solution of Twist-three Evolution Equations
hep-ph
A program dedicated to the numerical solution of the evolution equations for
twist-three multiparton correlation functions is presented. The solutions are
obtained by direct integration on a discretized momentum fraction grid. Both
flavor nonsinglet and flavor singlet evolution (in both $C$-parity sectors) can
be addressed. Physical applications include single spin asymmetries and the
subleading twist contribution to the polarized structure function $g_2$. An
arbitrary input is accepted for the initial distributions.
| arxiv topic:hep-ph |
arxiv_dataset-44311307.1372 | Clustering of Complex Networks and Community Detection Using Group
Search Optimization
cs.NE cs.DS
Group Search Optimizer(GSO) is one of the best algorithms, is very new in the
field of Evolutionary Computing. It is very robust and efficient algorithm,
which is inspired by animal searching behaviour. The paper describes an
application of GSO to clustering of networks. We have tested GSO against five
standard benchmark datasets, GSO algorithm is proved very competitive in terms
of accuracy and convergence speed.
| arxiv topic:cs.NE cs.DS |
arxiv_dataset-44321307.1472 | On the nature of sodium excess objects. I. Data and observed trends
astro-ph.CO
Several studies have reported the presence of sodium excess objects that have
neutral atomic absorption lines at 5895A (NaD) and 8190A that are deeper than
expected based on stellar population models. van Dokkum & Conroy proposed that
low-mass stars are more prevalent in massive early-type galaxies, which may
lead to a strong NaI8190 line strength. It is, however, necessary to test this
prediction against other prominent line indices in optical wavelengths. We
newly identified roughly a thousand NaD excess objects (NEOs) based on the NaD
line strength in the redshift range 0.00<z<0.08 from the SDSS DR7. The novelty
of this work is that galaxies were carefully identified through direct visual
inspection of SDSS images, and we systematically compared the properties of
NEOs and those of a control sample of normal galaxies. Note that the majority
of galaxies with high velocity dispersion (>250km/s) show NaD excess. Most
late-type NEOs have strong Hb line strengths and significant emission lines.
This implies that the presence of ISM and/or dust contributes to the increase
in NaD line strengths observed for these galaxies. In contrast, the majority of
early-type NEOs are predominantly luminous and massive systems. However, we
find that models used to reproduce the NaI8190 line strengths that adopt a
bottom-heavy IMF are not able to reproduce the observed NaD line strengths. By
comparing the observed NaD, Mgb and Fe5270 line strengths with those of the
models, we identify a plausible range of parameters. In these models, the
majority of early-type NEOs are alpha-enhanced ([a/Fe]~0.3), metal-rich
([Z/H]~0.3) and especially Na-enhanced ([Na/Fe]~0.3). Enhanced Na abundance is
a particularly compelling hypothesis for the increase in the strength of the
NaD line index in our early-type NEOs that appear devoid of dust, both in their
SDSS images and spectra.
| arxiv topic:astro-ph.CO |
arxiv_dataset-44331307.1572 | Existence of solutions for a mathematical model related to solid-solid
phase transitions in shape memory alloys
math.AP
We consider a strongly nonlinear PDE system describing solid-solid phase
transitions in shape memory alloys. The system accounts for the evolution of an
order parameter (related to different symmetries of the crystal lattice in the
phase configurations), of the stress (and the displacement), and of the
absolute temperature. The resulting equations present several technical
difficulties to be tackled: in particular, we emphasize the presence of
nonlinear coupling terms, higher order dissipative contributions, possibly
multivalued operators. As for the evolution of temperature, a highly nonlinear
parabolic equation has to be solved for a right hand side that is controlled
only in L^1. We prove the existence of a solution for a regularized version, by
use of a time discretization technique. Then, we perform suitable a priori
estimates which allow us pass to the limit and find a weak global-in-time
solution to the system.
| arxiv topic:math.AP |
arxiv_dataset-44341307.1672 | An inelastic x-ray study of phonon broadening and charge density wave
formation in ortho-II ordered YBa2Cu3O6.54
cond-mat.supr-con
Inelastic x-ray scattering is used to investigate charge density wave (CDW)
formation and the low-energy lattice dynamics of the underdoped high
temperature superconductor ortho-II YBa2Cu3O6.54. We find that, for a
temperature ~1/3 of the CDW onset temperature (~155 K), the CDW order is static
within the resolution of the experiment, that is the inverse lifetime is less
than 0.3 meV. In the same temperature region, low-energy phonons near the
ordering wavevector of the CDW show large increases in their linewidths. This
contrasts with the usual behavior in CDW systems where the phonon anomalies are
strongest near the CDW onset temperature
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-44351307.1772 | Simpler Sequential and Parallel Biconnectivity Augmentation
cs.DS
For a connected graph, a vertex separator is a set of vertices whose removal
creates at least two components and a minimum vertex separator is a vertex
separator of least cardinality. The vertex connectivity refers to the size of a
minimum vertex separator. For a connected graph $G$ with vertex connectivity $k
(k \geq 1)$, the connectivity augmentation refers to a set $S$ of edges whose
augmentation to $G$ increases its vertex connectivity by one. A minimum
connectivity augmentation of $G$ is the one in which $S$ is minimum. In this
paper, we focus our attention on connectivity augmentation of trees. Towards
this end, we present a new sequential algorithm for biconnectivity augmentation
in trees by simplifying the algorithm reported in \cite{nsn}. The simplicity is
achieved with the help of edge contraction tool. This tool helps us in getting
a recursive subproblem preserving all connectivity information. Subsequently,
we present a parallel algorithm to obtain a minimum connectivity augmentation
set in trees. Our parallel algorithm essentially follows the overall structure
of sequential algorithm. Our implementation is based on CREW PRAM model with
$O(\Delta)$ processors, where $\Delta$ refers to the maximum degree of a tree.
We also show that our parallel algorithm is optimal whose processor-time
product is O(n) where $n$ is the number of vertices of a tree, which is an
improvement over the parallel algorithm reported in \cite{hsu}.
| arxiv topic:cs.DS |
arxiv_dataset-44361307.1872 | Intelligent Hybrid Man-Machine Translation Quality Estimation
cs.CL
Inferring evaluation scores based on human judgments is invaluable compared
to using current evaluation metrics which are not suitable for real-time
applications e.g. post-editing. However, these judgments are much more
expensive to collect especially from expert translators, compared to evaluation
based on indicators contrasting source and translation texts. This work
introduces a novel approach for quality estimation by combining learnt
confidence scores from a probabilistic inference model based on human
judgments, with selective linguistic features-based scores, where the proposed
inference model infers the credibility of given human ranks to solve the
scarcity and inconsistency issues of human judgments. Experimental results,
using challenging language-pairs, demonstrate improvement in correlation with
human judgments over traditional evaluation metrics.
| arxiv topic:cs.CL |
arxiv_dataset-44371307.1972 | Regularity of solutions to quantum master equations: A stochastic
approach
math.PR
Applying probabilistic techniques we study regularity properties of quantum
master equations (QMEs) in the Lindblad form with unbounded coefficients; a
density operator is regular if, roughly speaking, it describes a quantum state
with finite energy. Using the linear stochastic Schr\"{o}dinger equation we
deduce that solutions of QMEs preserve the regularity of the initial states
under a general nonexplosion condition. To this end, we develop the
probabilistic representation of QMEs, and we prove the uniqueness of solutions
for adjoint quantum master equations. By means of the nonlinear stochastic
Schr\"{o}dinger equation, we obtain the existence of regular stationary
solutions for QMEs, under a Lyapunov-type condition.
| arxiv topic:math.PR |
arxiv_dataset-44381307.2072 | Weak Cyclic Monotonicity and Existence of Solutions of Differential
Inclusions
math.CA math.OC
The notion of weak cyclic monotonicity of set-valued maps generalizing the
cyclic monotonicity is introduced. The existence of solutions of differential
inclusions with compact, upper semi-continuous, not necessarily convex
right-hand sides in R^n is proved for weakly cyclic monotone right-hand sides.
| arxiv topic:math.CA math.OC |
arxiv_dataset-44391307.2172 | Partition Function of Chiral Boson on 2-Torus from Floreanini-Jackiw
Lagrangian
hep-th
We revisit the problem of quantizing a chiral boson on a torus. The
conventional approach is to extract the partition function of a chiral boson
from the path integral of a non-chiral boson. Instead we compute it directly
from the chiral boson Lagrangian of Floreanini and Jackiw modified by
topological terms involving auxiliary fields. A careful analysis of the
gauge-fixing condition for the extra gauge symmetry reproduces the correct
results for the free chiral boson, and has the advantage of being applicable to
a wider class of interacting chiral boson theories.
| arxiv topic:hep-th |
arxiv_dataset-44401307.2272 | Spin injection and detection in lanthanum- and niobium-doped SrTiO3
using the Hanle technique
cond-mat.mtrl-sci cond-mat.mes-hall
There has been much interest in the injection and detection of spin polarized
carriers in semiconductors for the purposes of developing novel spintronic
devices. Here we report the electrical injection and detection of
spin-polarized carriers into Nb-doped strontium titanate (STO) single crystals
and La-doped STO epitaxial thin films using MgO tunnel barriers and the
three-terminal Hanle technique. Spin lifetimes of up to ~100 ps are measured at
room temperature and vary little as the temperature is decreased to low
temperatures. However, the mobility of the STO has a strong temperature
dependence. This behavior and the carrier doping dependence of the spin
lifetime suggest that the spin lifetime is limited by spin-dependent scattering
at the MgO/STO interfaces, perhaps related to the formation of doping induced
Ti3+. Our results reveal a severe limitation of the three-terminal Hanle
technique for measuring spin lifetimes within the interior of the subject
material.
| arxiv topic:cond-mat.mtrl-sci cond-mat.mes-hall |
arxiv_dataset-44411307.2372 | Pedestrians moving in dark: Balancing measures and playing games on
lattices
physics.soc-ph nlin.CG
We present two conceptually new modeling approaches aimed at describing the
motion of pedestrians in obscured corridors:
* a Becker-D\"{o}ring-type dynamics
* a probabilistic cellular automaton model.
In both models the group formation is affected by a threshold. The
pedestrians are supposed to have very limited knowledge about their current
position and their neighborhood; they can form groups up to a certain size and
they can leave them. Their main goal is to find the exit of the corridor.
Although being of mathematically different character, the discussion of both
models shows that it seems to be a disadvantage for the individual to adhere to
larger groups. We illustrate this effect numerically by solving both model
systems. Finally we list some of our main open questions and conjectures.
| arxiv topic:physics.soc-ph nlin.CG |
arxiv_dataset-44421307.2472 | Cosmological evolution of the cosmological plasma with interpartial
scalar interaction. II. Formulation of mathematical model
gr-qc
On the basis of the relativistic kinetic theory the relativistic statistical
systems with scalar interaction particles are investigated. The self-consistent
system of the equations describing self-gravitating plasma with interpartial
scalar interaction is formulated, macroscopical laws of preservation are
received. The closed system of the equations describing cosmological models to
which the matter is presented by plasma with interpartial scalar interaction is
received.
| arxiv topic:gr-qc |
arxiv_dataset-44431307.2572 | The holographic dilaton
hep-th hep-ph
We study a set of examples of holographic duals to theories with spontaneous
breaking of conformal invariance in different dimensions. The geometries are
domain walls interpolating between two AdS spaces, with a non-trivial
background scalar field dual to a relevant operator. We comment on a subtlety
in the low momentum expansion pointed out in arXiv:1304.3051 for the case of
background gravity and revise the dynamical gravity results of arXiv:1207.0006,
where the dilaton pole was missing in the scalar-scalar and tensor-tensor
two-point functions. We compute the energy-momentum tensor and scalar two-point
functions and show that there is indeed a massless dilaton pole.
| arxiv topic:hep-th hep-ph |
arxiv_dataset-44441307.2672 | Index Coding Problem with Side Information Repositories
cs.IT math.IT
To tackle the expected enormous increase in mobile video traffic in cellular
networks, an architecture involving a base station along with caching femto
stations (referred to as helpers), storing popular files near users, has been
proposed [1]. The primary benefit of caching is the enormous increase in
downloading rate when a popular file is available at helpers near a user
requesting that file. In this work, we explore a secondary benefit of caching
in this architecture through the lens of index coding. We assume a system with
n users and constant number of caching helpers. Only helpers store files, i.e.
have side information. We investigate the following scenario: Each user
requests a distinct file that is not found in the set of helpers nearby. Users
are served coded packets (through an index code) by an omniscient base station.
Every user decodes its desired packet from the coded packets and the side
information packets from helpers nearby. We assume that users can obtain any
file stored in their neighboring helpers without incurring transmission costs.
With respect to the index code employed, we investigate two achievable schemes:
1) XOR coloring based on coloring of the side information graph associated with
the problem and 2)Vector XOR coloring based on fractional coloring of the side
information graph. We show that the general problem reduces to a canonical
problem where every user is connected to exactly one helper under some
topological constraints. For the canonical problem, with constant number of
helpers (k), we show that the complexity of computing the best XOR/vector XOR
coloring schemes are polynomial in the number of users n. The result exploits a
special complete bi-partite structure that the side information graphs exhibit
for any finite k.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-44451307.2772 | Spectral Properties of Quantum Walks on Rooted Binary Trees
math-ph math.MP
We define coined Quantum Walks on the infinite rooted binary tree given by
unitary operators $U(C)$ on an associated infinite dimensional Hilbert space,
depending on a unitary coin matrix $C\in U(3)$, and study their spectral
properties. For circulant unitary coin matrices $C$, we derive an equation for
the Carath\'eodory function associated to the spectral measure of a cyclic
vector for $U(C)$. This allows us to show that for all circulant unitary coin
matrices, the spectrum of the Quantum Walk has no singular continuous
component. Furthermore, for coin matrices $C$ which are orthogonal circulant
matrices, we show that the spectrum of the Quantum Walk is absolutely
continuous, except for four coin matrices for which the spectrum of $U(C)$ is
pure point.
| arxiv topic:math-ph math.MP |
arxiv_dataset-44461307.2872 | Laser Probing of Neutron-Rich Nuclei in Light Atoms
nucl-ex nucl-th physics.atom-ph
The neutron-rich 6He and 8He isotopes exhibit an exotic nuclear structure
that consists of a tightly bound 4He-like core with additional neutrons
orbiting at a relatively large distance, forming a halo. Recent experimental
efforts have succeeded in laser trapping and cooling these short-lived, rare
helium atoms, and have measured the atomic isotope shifts along the 4He-6He-8He
chain by performing laser spectroscopy on individual trapped atoms. Meanwhile,
the few-electron atomic structure theory, including relativistic and QED
corrections, has reached a comparable degree of accuracy in the calculation of
the isotope shifts. In parallel efforts, also by measuring atomic isotope
shifts, the nuclear charge radii of lithium and beryllium isotopes have been
studied. The techniques employed were resonance ionization spectroscopy on
neutral, thermal lithium atoms and collinear laser spectroscopy on beryllium
ions. Combining advances in both atomic theory and laser spectroscopy, the
charge radii of these light halo nuclei have now been determined for the first
time independent of nuclear structure models. The results are compared with the
values predicted by a number of nuclear structure calculations, and are used to
guide our understanding of the nuclear forces in the extremely neutron-rich
environment.
| arxiv topic:nucl-ex nucl-th physics.atom-ph |
arxiv_dataset-44471307.2972 | Global smooth solution to the simplified Ericksen-Leslie system in
dimension three
math.AP
In this paper, we consider Cauchy problem of simplified Ericksen-Leslie
system in dimension three. We establish the unique existence of global smooth
solution under some nonlinear conditions on initial data. However, we do not
need small conditions on initial data.
| arxiv topic:math.AP |
arxiv_dataset-44481307.3072 | Polar Surface Effects on the Thermal Conductivity in ZnO Nanowires: a
Shell-Like Surface Reconstruction-Induced Preserving Mechanism
cond-mat.mtrl-sci
We perform molecular dynamics (MD) simulations to investigate the effect of
polar surfaces on the thermal transport in zinc oxide (ZnO) nanowires. We find
that the thermal conductivity in nanowires with free polar (0001) surfaces is
much higher than in nanowires that have been stabilized with reduced charges on
the polar (0001) surfaces, and also hexagonal nanowires without any transverse
polar surfaces. From normal mode analysis, we show that the higher thermal
conductivity is due to a shell-like reconstruction that occurs for the free
polar surfaces. This shell-like reconstruction suppresses twisting motion in
the nanowires such that the bending phonon modes are not scattered by the other
phonon modes, and leads to substantially higher thermal conductivity in the ZnO
nanowire with free polar surfaces. Furthermore, the auto-correlation function
of the normal mode coordinate is utilized to extract the phonon lifetime, which
leads to a concise explanation for the higher thermal conductivity in ZnO
nanowires with free polar surfaces. Our work demonstrates that ZnO nanowires
without polar surfaces, which exhibit low thermal conductivity, are more
promising candidates for thermoelectric applications than nanowires with polar
surfaces (and also high thermal conductivity).
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-44491307.3172 | A Wintgen type inequality for surfaces in 4D neutral pseudo-Riemannian
space forms and its applications to minimal immersions
math.DG
Let $M$ be a space-like surface immersed in a 4-dimensional pseudo-Riemannian
space form $R^4_2(c)$ with constant sectional curvature $c$ and index two. In
the first part of this article, we prove that the Gauss curvature $K$, the
normal curvature $K^D$, and mean curvature vector $H$ of $M$ satisfy the
general inequality: $K+K^D\geq H,H +c$. In the second part, we investigate
space-like minimal surfaces in $R^4_2(c)$ which satisfy the equality case of
the inequality identically. Several classification results in this respect are
then obtained.
| arxiv topic:math.DG |
arxiv_dataset-44501307.3272 | Approximate Cech Complexes in Low and High Dimensions
cs.CG math.AT
\v{C}ech complexes reveal valuable topological information about point sets
at a certain scale in arbitrary dimensions, but the sheer size of these
complexes limits their practical impact. While recent work introduced
approximation techniques for filtrations of (Vietoris-)Rips complexes, a
coarser version of \v{C}ech complexes, we propose the approximation of \v{C}ech
filtrations directly.
For fixed dimensional point set $S$, we present an approximation of the
\v{C}ech filtration of $S$ by a sequence of complexes of size linear in the
number of points. We generalize well-separated pair decompositions (WSPD) to
well-separated simplicial decomposition (WSSD) in which every simplex defined
on $S$ is covered by some element of WSSD. We give an efficient algorithm to
compute a linear-sized WSSD in fixed dimensional spaces. Using a WSSD, we then
present a linear-sized approximation of the filtration of \v{C}ech complex of
$S$.
We also present a generalization of the known fact that the Rips complex
approximates the \v{C}ech complex by a factor of $\sqrt{2}$. We define a class
of complexes that interpolate between \v{C}ech and Rips complexes and that,
given any parameter $\eps > 0$, approximate the \v{C}ech complex by a factor
$(1+\eps)$. Our complex can be represented by roughly $O(n^{\lceil
1/2\eps\rceil})$ simplices without any hidden dependence on the ambient
dimension of the point set. Our results are based on an interesting link
between \v{C}ech complex and coresets for minimum enclosing ball of
high-dimensional point sets. As a consequence of our analysis, we show improved
bounds on coresets that approximate the radius of the minimum enclosing ball.
| arxiv topic:cs.CG math.AT |
arxiv_dataset-44511307.3372 | Fractional decay bounds for nonlocal zero order heat equations
math.AP
In this paper we obtain bounds for the decay rate for solutions to the
nonlocal problem $\partial_t u(t,x) = \int_{\R^n} J(x,y)[u(t,y) - u(t,x)] dy$.
Here we deal with bounded kernels $J$ but with polynomial tails, that is, we
assume a lower bound of the form $J(x,y) \geq c_1|x-y|^{-(n + 2\sigma)}$, for
$|x - y| > c_2$. Our estimates takes the form $\|u(t)\|_{L^q(\R^n)} \leq C
t^{-\frac{n}{2\sigma} (1 - \frac{1}{q})}$ for $t$ large.
| arxiv topic:math.AP |
arxiv_dataset-44521307.3472 | A Set of Questions in Combinatorial and Metric Geometry
math.MG math.CO
We briefly introduce several problems: (1) a generalization of the convex
fair partition conjecture, (2) on non-trivial invariants among polyhedrons that
can be formed from the same set of face polygons, (3) two questions on
assembling rectangular tiles to form larger rectangles and (4) on convex
regions which maximize and minimize the diameter for specified area and
perimeter. For each question, we discuss partial solutions and indicate aspects
that to our knowledge, await exploration.
| arxiv topic:math.MG math.CO |
arxiv_dataset-44531307.3572 | Electroweak Measurements of Neutron Densities in CREX and PREX at JLab,
USA
nucl-ex
Measurement of the parity-violating electron scattering asymmetry is an
established technique at Jefferson Lab and provides a new opportunity to
measure the weak charge distribution and hence pin down the neutron radius in
nuclei in a relatively clean and model-independent way. This is because the Z
boson of the weak interaction couples primarily to neutrons. We will describe
the PREX and CREX experiments on ${}^{208}$Pb and ${}^{48}$Ca respectively;
these are both doubly-magic nuclei whose first excited state can be
discriminated by the high resolution spectrometers at JLab. The heavier lead
nucleus, with a neutron excess, provides an interpretation of the neutron skin
thickness in terms of properties of bulk neutron matter. For the lighter
${}^{48}$Ca nucleus, which is also rich in neutrons, microscopic nuclear theory
calculations are feasible and are sensitive to poorly constrained 3-neutron
forces.
| arxiv topic:nucl-ex |
arxiv_dataset-44541307.3672 | Transformation Method for Solving Hamilton-Jacobi-Bellman Equation for
Constrained Dynamic Stochastic Optimal Allocation Problem
q-fin.PM
In this paper we propose and analyze a method based on the Riccati
transformation for solving the evolutionary Hamilton-Jacobi-Bellman equation
arising from the stochastic dynamic optimal allocation problem. We show how the
fully nonlinear Hamilton-Jacobi-Bellman equation can be transformed into a
quasi-linear parabolic equation whose diffusion function is obtained as the
value function of certain parametric convex optimization problem. Although the
diffusion function need not be sufficiently smooth, we are able to prove
existence, uniqueness and derive useful bounds of classical H\"older smooth
solutions. We furthermore construct a fully implicit iterative numerical scheme
based on finite volume approximation of the governing equation. A numerical
solution is compared to a semi-explicit traveling wave solution by means of the
convergence ratio of the method. We compute optimal strategies for a portfolio
investment problem motivated by the German DAX 30 Index as an example of
application of the method.
| arxiv topic:q-fin.PM |
arxiv_dataset-44551307.3772 | Entanglement is Sometimes Enough
quant-ph physics.optics
For many decades the word "entanglement" has been firmly attached to the
world of quantum mechanics. So is the phrase "Bell violation". Here we show,
without contradicting quantum mechanics, that classical non-deterministic
fields also provide a natural basis for entanglement and Bell analyses.
Surprisingly, such fields are not eliminated by the Clauser-Horne-Shimony-Holt
Bell violation test as viable alternatives to quantum theory. An experimental
setup for verification is proposed.
| arxiv topic:quant-ph physics.optics |
arxiv_dataset-44561307.3872 | Bicriteria data compression
cs.IT cs.DS math.IT
The advent of massive datasets (and the consequent design of high-performing
distributed storage systems) have reignited the interest of the scientific and
engineering community towards the design of lossless data compressors which
achieve effective compression ratio and very efficient decompression speed.
Lempel-Ziv's LZ77 algorithm is the de facto choice in this scenario because of
its decompression speed and its flexibility in trading decompression speed
versus compressed-space efficiency. Each of the existing implementations offers
a trade-off between space occupancy and decompression speed, so software
engineers have to content themselves by picking the one which comes closer to
the requirements of the application in their hands. Starting from these
premises, and for the first time in the literature, we address in this paper
the problem of trading optimally, and in a principled way, the consumption of
these two resources by introducing the Bicriteria LZ77-Parsing problem, which
formalizes in a principled way what data-compressors have traditionally
approached by means of heuristics. The goal is to determine an LZ77 parsing
which minimizes the space occupancy in bits of the compressed file, provided
that the decompression time is bounded by a fixed amount (or vice-versa). This
way, the software engineer can set its space (or time) requirements and then
derive the LZ77 parsing which optimizes the decompression speed (or the space
occupancy, respectively). We solve this problem efficiently in O(n log^2 n)
time and optimal linear space within a small, additive approximation, by
proving and deploying some specific structural properties of the weighted graph
derived from the possible LZ77-parsings of the input file. The preliminary set
of experiments shows that our novel proposal dominates all the highly
engineered competitors, hence offering a win-win situation in theory&practice.
| arxiv topic:cs.IT cs.DS math.IT |
arxiv_dataset-44571307.3972 | Minimal flat Lorentzian surfaces in Lorentzian complex space forms
math.DG
In this article we study minimal flat Lorentzian surfaces in Lorentzian
complex space forms. First we prove that, for minimal flat Lorentzian surfaces
in a Lorentzian complex form, the equation of Ricci is a consequence of the
equations of Gauss and Codazzi. Then we classify minimal flat Lorentzian
surfaces in the Lorentzian complex plane ${\bf C}^2_1$. Finally, we classify
minimal flat slant surfaces in Lorentzian complex projective plane $CP^2_1$ and
in Lorentzian complex hyperbolic plane $CH^2_1$.
| arxiv topic:math.DG |
arxiv_dataset-44581307.4072 | Schwarzschild-Couder telescope for the Cherenkov Telescope Array:
Development of the Optical System
astro-ph.IM
The CTA (Cherenkov Telescope Array) is the next generation ground-based
experiment for very high-energy (VHE) gamma-ray observations. It will integrate
several tens of imaging atmospheric Cherenkov telescopes (IACTs) with different
apertures into a single astronomical instrument. The US part of the CTA
collaboration has proposed and is developing a novel IACT design with a
Schwarzschild-Couder (SC) aplanatic two mirror optical system. In comparison
with the traditional single mirror Davies-Cotton IACT the SC telescope, by
design, can accommodate a wide field-of-view, with significantly improved
imaging resolution. In addition, the reduced plate scale of an SC telescope
makes it compatible with highly integrated cameras assembled from silicon photo
multipliers. In this submission we report on the status of the development of
the SC optical system, which is part of the effort to construct a full-scale
prototype telescope of this type at the Fred Lawrence Whipple Observatory in
southern Arizona.
| arxiv topic:astro-ph.IM |
arxiv_dataset-44591307.4172 | Magellanic Cloud stars with TiO bands in emission: binary post-RGB/AGB
stars or young stellar objects?
astro-ph.SR
Fourteen stars from a sample of Magellanic Cloud objects selected to have a
mid-infrared flux excess have been found to also show TiO bands in emission.
The mid-infrared dust emission and the TiO band emission indicate that these
stars have large amounts of hot circumstellar dust and gas in close proximity
to the central star. The luminosities of the sources are typically several
thousand L_sun while the effective temperatures are 4000-8000 K. Such stars
could be post-AGB stars of mass 0.4-0.8 M_sun or pre-main-sequence stars (young
stellar objects) with masses of 7-19 M_sun. If the stars are pre-main-sequence
stars, they are substantially cooler and younger than stars at the birth line
where Galactic protostars are first supposed to become optically visible out of
their molecular clouds. They should therefore be hidden in their present
evolutionary state. The second explanation for these stars is that they are
post-AGB or post-RGB stars that have recently undergone a binary interaction
when the red giant of the binary system filled its Roche lobe. Being
oxygen-rich, they have gone through this process before becoming carbon stars.
Most of the stars vary slowly on timescales of 1000 days or more suggesting a
changing circumstellar environment. Apart from the slow variations, most stars
also show variability with periods of tens to hundreds of days. One star shows
a period that is rapidly decreasing and we speculate that this star may have
accreted a large blob of gas and dust onto a disk whose orbital radius is
shrinking rapidly. Another star has Cepheid-like pulsations of rapidly
increasing amplitude suggesting a rapid rate of evolution. Seven stars show
quasi-periodic variability and one star has a light curve similar to that of an
eclipsing binary.
| arxiv topic:astro-ph.SR |
arxiv_dataset-44601307.4272 | The Nullity Theorem for Principal Pivot Transform
math.CO
We generalize the nullity theorem of Gustafson [Linear Algebra Appl. (1984)]
from matrix inversion to principal pivot transform. Several special cases of
the obtained result are known in the literature, such as a result concerning
local complementation on graphs. As an application, we show that a particular
matrix polynomial, the so-called nullity polynomial, is invariant under
principal pivot transform.
| arxiv topic:math.CO |
arxiv_dataset-44611307.4372 | Automorphic forms for triangle groups
math.NT hep-th math.GR
For triangle groups, the (quasi-)automorphic forms are known just as
explicitly as for the modular group SL$(2,\bbZ)$. We collect these expressions
here, and then interpret them using the Halphen differential equation. We study
the arithmetic properties of their Fourier coefficients at cusps and Taylor
coefficients at elliptic fixed-points --- in both cases integrality is related
to the arithmeticity of the triangle group. As an application of our formulas,
we provide an explicit modular interpretation of periods of 14 families of
Calabi-Yau threefolds over the thrice-punctured sphere.
| arxiv topic:math.NT hep-th math.GR |
arxiv_dataset-44621307.4472 | Weighted Automata and Monadic Second Order Logic
cs.LO cs.FL
Let S be a commutative semiring. M. Droste and P. Gastin have introduced in
2005 weighted monadic second order logic WMSOL with weights in S. They use a
syntactic fragment RMSOL of WMSOL to characterize word functions (power series)
recognizable by weighted automata, where the semantics of quantifiers is used
both as arithmetical operations and, in the boolean case, as quantification.
Already in 2001, B. Courcelle, J.Makowsky and U. Rotics have introduced a
formalism for graph parameters definable in Monadic Second order Logic, here
called MSOLEVAL with values in a ring R. Their framework can be easily adapted
to semirings S. This formalism clearly separates the logical part from the
arithmetical part and also applies to word functions.
In this paper we give two proofs that RMSOL and MSOLEVAL with values in S
have the same expressive power over words. One proof shows directly that
MSOLEVAL captures the functions recognizable by weighted automata. The other
proof shows how to translate the formalisms from one into the other.
| arxiv topic:cs.LO cs.FL |
arxiv_dataset-44631307.4572 | Bose-Fermi competition in holographic metals
hep-th
We study the holographic dual of a finite density system with both bosonic
and fermionic degrees of freedom. There is no evidence for a universal
bose-dominated ground state. Instead, depending on the relative conformal
weights the preferred groundstate is either pure AdS-Reissner-Nordstrom, a
holographic superconductor, an electron star, or a novel mixed state that is
best characterized as a hairy electron star.
| arxiv topic:hep-th |
arxiv_dataset-44641307.4672 | Huge thermoelectric effects in ferromagnet-superconductor junctions in
the presence of a spin-splitting field
cond-mat.supr-con
We show that a huge thermoelectric effect can be observed by contacting a
superconductor whose density of states is spin-split by a Zeeman field with a
ferromagnet with a non-zero polarization. The resulting thermopower exceeds
$k_B/e$ by a large factor, and the thermoelectric figure of merit $ZT$ can far
exceed unity, leading to heat engine efficiencies close to the Carnot limit. We
also show that spin-polarized currents can be generated in the superconductor
by applying a temperature bias.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-44651307.4772 | Ideal hypersurfaces of Euclidean four-space
math.DG
The notion of ideal immersions was introduced by the author in 1990s. Roughly
speaking, an ideal immersion of a Riemannian manifold into a real space form is
a nice isometric immersion which produces the least possible amount of tension
from the ambient space at each point.
In this paper, we classify all ideal hypersurfaces with two distinct
principal curvatures in the Euclidean 4-space $\mathbb E^4$. Moreover, we prove
that such ideal hypersurfaces are always rigid. Furthermore, we show that
non-minimal ideal hypersurfaces with three distinct principal curvatures in
$\mathbb E^4$ are also rigid. On the other hand, we provide explicit examples
to illustrate that minimal ideal hypersurfaces with three principal curvatures
in $\mathbb E^4$ are not necessarily rigid.
| arxiv topic:math.DG |
arxiv_dataset-44661307.4872 | Spin/parity of Higgs-like particle at D0
hep-ex hep-ph
We present prospects for tests of different spin and parity hypotheses for a
particle $H$ of mass 125 GeV produced in association with a vector boson and
decaying into a pair of b-quarks. We use the combined analysis of the WH->lvbb,
ZH->llbb, and ZH-> vvbb channels based on the full Run II dataset collected at
$\sqrt s=1.96$ TeV with the \dzero\ detector at the Fermilab Tevatron collider.
| arxiv topic:hep-ex hep-ph |
arxiv_dataset-44671307.4972 | Still No Rindler Firewalls
hep-th gr-qc
There has been much discussion on the possibility of firewalls at the
horizon-scale in black hole physics, including questions regarding the presence
or absence of firewalls at apparent horizons, such as the Rindler horizon and
the horizon of the Poincar\'{e} patch of Anti-de Sitter space. We argue against
the presence of such apparent firewalls by demonstrating that one recent
argument for firewalls in black holes does not extend to these cases. We also
include some brief remarks on some claims in the recent firewall literature.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-44681307.5072 | Reanalysis of the FEROS observations of HIP 11952
astro-ph.SR astro-ph.EP
Aims. We reanalyze FEROS observations of the star HIP 11952 to reassess the
existence of the proposed planetary system. Methods. The radial velocity of the
spectra were measured by cross-correlating the observed spectrum with a
synthetic template. We also analyzed a large dataset of FEROS and HARPS
archival data of the calibrator HD 10700 spanning over more than five years. We
compared the barycentric velocities computed by the FEROS and HARPS pipelines.
Results. The barycentric correction of the FEROS-DRS pipeline was found to be
inaccurate and to introduce an artificial one-year period with a semi-amplitude
of 62 m/s. Thus the reanalysis of the FEROS data does not support the existence
of planets around HIP 11952.
| arxiv topic:astro-ph.SR astro-ph.EP |
arxiv_dataset-44691307.5172 | Evidence for X(3872) from DD* scattering on the lattice
hep-lat hep-ph
A candidate for the charmonium(like) state X(3872) is found 11 +/- 7 MeV
below the DD* threshold using dynamical Nf=2 lattice simulation with J^PC=1^++
and I=0. This is the first lattice simulation that establishes a candidate for
X(3872) in addition to the nearby scattering states D D* and J/psi omega, which
inevitably have to be present in dynamical QCD. We extract large and negative
DD* scattering length a_0=-1.7 +/- 0.4 fm and the effective range r_0=0.5 +/-
0.1 fm, but their reliable determination will have to wait for a simulation on
a larger volume. In I=1 channel, only the D D* and J/psi rho scattering states
are found and no candidate for X(3872). This is in agreement with the
interpretation that X(3872) is dominantly I=0, while its small I=1 component
arises solely from the isospin breaking and is therefore absent in our
simulation with m_u=m_d.
| arxiv topic:hep-lat hep-ph |
arxiv_dataset-44701307.5272 | Demonstration of white light cavity effect using stimulated Brillouin
scattering in a fiber loop
physics.optics
A passive white light cavity (WLC) based on a fiber resonator can be used for
high-bandwidth optical data buffering. Here, we report on experimental studies
of such a WLC, employing stimulated Brillouin scattering (SBS)for producing the
negative dispersion, using two different configurations. In one configuration,
an absorption peak produced by a Brillouin pump is used. In the other
configuration, two gain peaks produced by two separate Brillouin pumps are
employed. In each case, we see evidence of the WLC effect. However, the range
of parameters accessible experimentally limits the degree of the WLC effect
significantly. We present a theoretical analysis for the optimal combinations
of parameters, such as a high Brillouin gain coefficient and a low transmission
loss, necessary for achieving the condition of a vanishing group index, as
required for creating an ideal WLC.
| arxiv topic:physics.optics |
arxiv_dataset-44711307.5372 | A Particle-Water Based Model for Water Retention Hysteresis
cond-mat.soft
A particle-water discrete element based approach to describe water movement
in partially saturated granular media is presented and tested. Water potential
is governed by both capillary bridges, dominant at low saturations, and the
pressure of entrapped air, dominant at high saturations. The approach captures
the hysteresis of water retention during wetting and drainage by introducing
the local evolution of liquid-solid contact angles at the level of pores and
grains. Extensive comparisons against experimental data are presented. While
these are made without the involvement of any fitting parameters, the method
demonstrates relative high success by achieving a correlation coefficient of at
least 82%, and mostly above 90%. For the tested materials with relatively
mono-disperse grain size, the hysteresis of water retention during cycles of
wetting and drainage has been shown to arise from the dynamics of solid-liquid
contact angles as a function of local liquid volume changes.
| arxiv topic:cond-mat.soft |
arxiv_dataset-44721307.5472 | Visualization of superposition states and Raman processes with
two-dimensional atomic deflection
quant-ph
Deflection of atoms in \Lambda-type configuration passing through two crossed
standing light waves is proposed for probing and visualization of atomic
superposition states. For this goal, we use both the large-dispersive and
Raman-resonant regimes of atom-field interaction giving rise to a
position-dependent phase shifts of fields and perform double simultaneous
spatial measurements on an atom. In this way, it is demonstrated that the
deflection spatial patterns of atoms in \Lambda-configuration passing through
modes of standing waves are essentially modified if the atoms are initially
prepared in a coherent superposition of its low levels states as well as when
the superposition states are created during the process of deflection. The
similar results take place for the joint momentum distribution of atoms.
Further, considering both one-photon and two-photon excitation regimes of
\Lambda-atoms we also illustrate that the two-dimensional patterns of defected
atoms qualitatively reflects the efficiency of the Raman processes.
| arxiv topic:quant-ph |
arxiv_dataset-44731307.5572 | Vector bileptons and the decays $h\rightarrow \gamma\gamma,Z\gamma$
hep-ph
Takeing into account of the constraints on the relevant parameters from the
muon anomalous magnetic moment, we consider the contributions of the vector
bileptons $V^{\pm}$ and $U^{\pm\pm}$ predicted by the reduced minimal 331 model
to the Higgs decay channels $h \rightarrow \gamma \gamma$ and $Z\gamma$. Our
numerical results show that the vector bileptons can enhance the partial width
$\Gamma(h\rightarrow \gamma\gamma)$, while reduce the partial width
$\Gamma(h\rightarrow Z\gamma)$, which are anti-correlated. With reasonable
values of the relevant free parameters, the vector bileptons can explain the
$LHC$ data for the $\gamma\gamma$ signal. If the $CMS$ data persists, the value
of the free parameters $ \lambda_{2}$ and $ \lambda_{3}$ should be severe
constrained.
| arxiv topic:hep-ph |
arxiv_dataset-44741307.5672 | A scalable, fast and multichannel arbitrary waveform generator
physics.ins-det physics.atom-ph quant-ph
This article reports on development of a multichannel arbitrary waveform
generator (MAWG), which simultaneously generates arbitrary voltage waveforms on
24 independent channels with a dynamic update rate of up to 25 Msps. A
real-time execution of a single waveform and/or sequence of multiple waveforms
in succession, with a user programmable arbitrary sequence order is provided
under the control of a stand-alone sequencer circuit implemented using an FPGA.
The device is operated using an internal clock and can be synced to other
devices by means of the TTL pulses. The device can be used for output voltages
in the range of up to +-9 V with a drift rate below +-10 uV/min and a maximum
deviation less than +-300 uVpp over a period of two hours.
| arxiv topic:physics.ins-det physics.atom-ph quant-ph |
arxiv_dataset-44751307.5772 | Hermitian realizations of kappa-Minkowski spacetime
hep-th math-ph math.MP
General realizations, star products and plane waves for kappa-Minkowski
spacetime are considered. Systematic construction of general hermitian
realization is presented, with special emphasis on noncommutative plane waves
and hermitian star product. Few examples are elaborated and possible physical
applications are mentioned.
| arxiv topic:hep-th math-ph math.MP |
arxiv_dataset-44761307.5872 | Kondo effect of cobalt adatom on zigzag graphene nanoribbon
cond-mat.mes-hall
Based on ab-initio calculations we discuss Kondo effect due to Co adatom on
graphene zigzag nanoribbon. Co atom located at hollow site behaves as spin S =
1/2 impurity with dxz and dyz orbitals contributing to magnetic moment.
Dynamical correlations are analyzed with the use of complementary
approximations: mean field slave boson approach, noncrossing approximation and
equation of motion method. The impact of interplay between spin and orbital
degrees of freedom together with the effect of peculiarities of electronic and
magnetic structure of nanoribbon on many-body resonances is examined.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-44771307.5972 | Dielectric Environment Effect on Carrier Mobility of Graphene
Double-Layer Structure
cond-mat.mes-hall cond-mat.mtrl-sci
We have theoretically studied the dielectric environment effect on the
charged-impurity-limited carrier mobility of graphene double-layer structure
(GDLS) on the basis of the Boltzmann transport theory. In this system, two
graphene layers are separated by a dielectric barrier layer. It is pointed out
that the carrier mobility strongly depends on the dielectric constant of the
barrier layer when the interlayer distance becomes larger than the inverse of
the Fermi wave vector. Moreover, the conditions to improve the
charged-impurity-limited carrier mobility of the GDLS are evaluated.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-44781307.6072 | Near field of an oscillating electric dipole and cross-polarization of a
collimated beam of light: two sides of the same coin
physics.optics
We address the question of whether there exists a hidden relationship between
the near-field distribution generated by an oscillating electric dipole and the
so-called cross polarization of a collimated beam of light. We find that the
answer is affirmative by showing that the complex field distributions occurring
in both cases have a common physical origin: the requirement that the
electromagnetic fields must be transverse.
| arxiv topic:physics.optics |
arxiv_dataset-44791307.6172 | Can the coincidence problem be solved by a cosmological model of coupled
dark energy and dark matter?
astro-ph.CO
Motivated by the cosmological constant and the coincidence problems, we
consider a cosmological model where the dark sectors are interacting together
through a phenomenological decay law $\dot{\rho}_{\Lambda}=Q\rho_{\Lambda}^n$
in a FRW spacetime with spatial curvature. We show that the only value of $n$
for which the late-time matter energy density to dark energy density ratio
($r_m=\rho_m/\rho_{\Lambda}$) is constant (which could provide an explanation
to the coincidence problem) is $n=3/2$. For each value of $Q$, there are two
distinct solutions. One of them involves a spatial curvature approaching zero
at late times ($\rho_k\approx0$) and is stable when the interaction is weaker
than a critical value ${Q_0=-\sqrt{32\pi G/c^2}}$. The other one allows for a
non-negligible spatial curvature ($\rho_k\napprox0$) at late times and is
stable when the interaction is stronger than $Q_0$. We constrain the model
parameters using various observational data (SNeIa, GRB, CMB, BAO, OHD). The
limits obtained on the parameters exclude the regions where the cosmological
constant problem is significantly ameliorated and do not allow for a completely
satisfying explanation for the coincidence problem.
| arxiv topic:astro-ph.CO |
arxiv_dataset-44801307.6272 | On Axiomatization of Inconsistency Indicators for Pairwise Comparisons
cs.DM cs.GT
We examine the notion of inconsistency in pairwise comparisons and propose an
axiomatization which is independent of any method of approximation or the
inconsistency indicator definition (e.g., Analytic Hierarchy Process, AHP). It
has been proven that the eigenvalue-based inconsistency (proposed as a part of
AHP) is incorrect.
| arxiv topic:cs.DM cs.GT |
arxiv_dataset-44811307.6372 | Inventions on Soft Keyboards -- A TRIZ Based Analysis
cs.HC
The soft keyboards are onscreen representation of physical keyboard having
alphanumeric characters and other controls. The user operates the soft keyboard
with the mouse, a stylus or other pointing device. The soft keys dont have any
mechanical component.
The soft keyboards are used in many public places for informational purpose,
educational systems and financial transactional systems. A soft keyboard is
convenient in some cases where a hard keyboard is difficult to manage. The soft
keyboard is a substitute of a physical keyboard and is displayed on the screen.
It displays the same type of alphanumeric and control keys like the keys on the
actual keyboard.
There are many inventions on a soft keyboard which makes the soft keyboard
more efficient and effective. This article illustrates some inventions on soft
keyboards from US patent database.
| arxiv topic:cs.HC |
arxiv_dataset-44821307.6472 | Order, intermittency and pressure fluctuations in a system of
proliferating rods
cond-mat.soft q-bio.TO
Non-motile elongated bacteria confined in two-dimensional open micro-channels
can exhibit collective motion and form dense monolayers with nematic order if
the cells proliferate, i.e., grow and divide. Using soft molecular dynamics
simulations of a system of rods interacting through short range mechanical
forces, we study the effects of the cell growth rate, the cell aspect ratio and
of the sliding friction on nematic ordering and on pressure fluctuations in
confined environments. Our results indicate that rods with aspect ratio >3.0
reach quasi-perfect nematic states at low sliding friction. At higher
frictions, the global nematic order parameter shows intermittent fluctuations
due to sudden losses of order and the time intervals between these bursts are
power-law distributed. The pressure transverse to the channel axis can vary
abruptly in time and shows hysteresis due to lateral crowding effects. The
longitudinal pressure field is on average correlated to nematic order, but it
is locally very heterogeneous and its distribution follows an inverse
power-law, in sharp contrast with non-active granular systems. We discuss some
implications of these findings for tissue growth.
| arxiv topic:cond-mat.soft q-bio.TO |
arxiv_dataset-44831307.6572 | The 1st Fermi LAT SNR Catalog: the Impact of Interstellar Emission
Modeling
astro-ph.HE
Galactic interstellar emission contributes substantially to Fermi LAT
observations in the Galactic plane, the location of the majority of supernova
remnants (SNRs). To explore some systematic effects on SNRs' properties caused
by interstellar emission modeling, we have developed a method comparing the
official LAT interstellar emission model results to eight alternative models.
We created the eight alternative Galactic interstellar models by varying a few
input parameters to GALPROP, namely the height of the cosmic ray propagation
halo, cosmic ray source distribution in the Galaxy, and atomic hydrogen spin
temperature. We have analyzed eight representative SNRs chosen to encompass a
range of Galactic locations, extensions, and spectral properties using the
eight different interstellar emission models. We will present the results and
method in detail and discuss the implications for studies such as the 1st Fermi
LAT SNR Catalog.
| arxiv topic:astro-ph.HE |
arxiv_dataset-44841307.6672 | Lagrangian acceleration of passive tracers in statistically-steady
rotating turbulence
physics.flu-dyn
The statistical properties of the Lagrangian acceleration vector of passive
tracers in statistically-steady rotating turbulence is studied by Particle
Tracking Velocimetry. Direct effects of the background rotation are the
suppression of high-acceleration events parallel to the (vertical) rotation
axis, the enhancement of high-acceleration events for the horizontal
acceleration, and the strong amplification of the auto-correlation of the
acceleration component perpendicular to both the rotation vector \Omega\ and
local velocity vector u. The auto-correlation of the acceleration component in
the plane set up by \Omega\ and u is only mildly enhanced.
| arxiv topic:physics.flu-dyn |
arxiv_dataset-44851307.6772 | Multiwavelength observations and modeling of 1ES 1959+650 in a low flux
state
astro-ph.HE
We report on the VERITAS observations of the high-frequency peaked BL Lac
object 1ES 1959+650 in the period 2007-2011. This source is detected at TeV
energies by VERITAS at 16.4 standard deviation (sigma) significance in 7.6
hours of observation in a low flux state. A multiwavelength spectral energy
distribution (SED) is constructed from contemporaneous data from VERITAS,
Fermi-LAT, RXTE PCA, and Swift UVOT. Swift XRT data is not included in the SED
due to a lack of simultaneous observations with VERITAS. In contrast to the
orphan gamma-ray flare exhibited by this source in 2002, the X-ray flux of the
source is found to vary by an order of magnitude, while other energy regimes
exhibit less variable emission. A quasi-equilibrium synchrotron self-Compton
model with an additional external radiation field is used to describe three
SEDs corresponding to the lowest, highest, and average X-ray states. The
variation in the X-ray spectrum is modeled by changing the electron injection
spectral index, with minor adjustments of the kinetic luminosity in electrons.
This scenario produces small-scale flux variability of order >~2 in the HE (E>1
MeV) and VHE (E>100 GeV) gamma-ray regimes, which is corroborated by the
Fermi-LAT, VERITAS, and Whipple 10m telescope light curves.
| arxiv topic:astro-ph.HE |
arxiv_dataset-44861307.6872 | Effective equations for matter-wave gap solitons in higher-order
transversal states
cond-mat.quant-gas nlin.PS
We demonstrate that an important class of nonlinear stationary solutions of
the three-dimensional (3D) Gross-Pitaevskii equation (GPE) exhibiting
nontrivial transversal configurations can be found and characterized in terms
of an effective one-dimensional (1D) model. Using a variational approach we
derive effective equations of lower dimensionality for BECs in $(m,n_{r})$
transversal states (states featuring a central vortex of charge $m$ as well as
$n_{r}$ concentric zero-density rings at every $z$ plane) which provides us
with a good approximate solution of the original 3D problem. Since the
specifics of the transversal dynamics can be absorbed in the renormalization of
a couple of parameters, the functional form of the equations obtained is
universal. The model proposed finds its principal application in the study of
the existence and classification of 3D gap solitons supported by 1D optical
lattices, where in addition to providing a good estimate for the 3D wave
functions it is able to make very good predictions for the $\mu(N)$ curves
characterizing the different fundamental families. We have corroborated the
validity of our model by comparing its predictions with those from the exact
numerical solution of the full 3D GPE.
| arxiv topic:cond-mat.quant-gas nlin.PS |
arxiv_dataset-44871307.6972 | Electron-phonon coupling in cuprate and iron-based superconductors
revealed by Raman scattering
cond-mat.supr-con cond-mat.mtrl-sci cond-mat.str-el
Electron-phonon coupling (EPC) is one of the most common and fundamental
interactions in solids. It not only dominates many basic dynamic processes like
resistivity, thermal conductivity etc, but also provides the pairing glue in
conventional superconductors. But in high-temperature superconductors (HTSC),
it is still controversial whether or not EPC is in favor of paring. Despite the
controversies, many experiments have provided clear evidence for EPC in HTSC.
In this paper, we briefly review EPC in cuprate and iron-based superconducting
systems revealed by Raman scattering. We introduce how to extract the coupling
information through phonon lineshape. Then we discuss the strength of EPC in
different HTSC systems and possible factors affecting the strength. The
comparative study between Raman phonon theories and experiments allows us to
gain insight into some crucial electronic properties, especially
superconductivity. Finally we summarize and compare EPC in the two existing
HTSC systems, and discuss what role it may play in HTSC.
| arxiv topic:cond-mat.supr-con cond-mat.mtrl-sci cond-mat.str-el |
arxiv_dataset-44881307.7072 | Molecular Dynamics Simulations of Single-Layer Molybdenum Disulphide
(MoS2): Stillinger-Weber Parametrization, Mechanical Properties, and Thermal
Conductivity
cond-mat.mtrl-sci
We present a parameterization of the Stillinger-Weber potential to describe
the interatomic interactions within single-layer MoS2 (SLMoS2). The potential
parameters are fitted to an experimentally-obtained phonon spectrum, and the
resulting empirical potential provides a good description for the energy gap
and the crossover in the phonon spectrum. Using this potential, we perform
classical molecular dynamics simulations to study chirality, size, and strain
effects on the Young's modulus and the thermal conductivity of SLMoS2. We
demonstrate the importance of the free edges on the mechanical and thermal
properties of SLMoS2 nanoribbons. Specifically, while edge effects are found to
reduce the Young's modulus of SLMoS2 nanoribbons, the free edges also reduce
the thermal stability of SLMoS2 nanoribbons, which may induce melting well
below the bulk melt temperature. Finally, uniaxial strain is found to
efficiently manipulate the thermal conductivity of infinite, periodic SLMoS2.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-44891307.7172 | Structure and Dynamics of Coauthorship, Citation, and Impact within CSCW
cs.DL cs.SI physics.soc-ph
CSCW has stabilized as an interdisciplinary venue for computer, information,
cognitive, and social scientists but has also undergone significant changes in
its format in recent years. This paper uses methods from social network
analysis and bibliometrics to re-examine the structures of CSCW a decade after
its last systematic analysis. Using data from the ACM Digital Library, we
analyze changes in structures of coauthorship and citation between 1986 and
2013. Statistical models reveal significant but distinct patterns between
papers and authors in how brokerage and closure in these networks affects
impact as measured by citations and downloads. Specifically, impact is unduly
influenced by structural position, such that ideas introduced by those in the
core of the CSCW community (e.g., elite researchers) are advantaged over those
introduced by peripheral participants (e.g., newcomers). This finding is
examined in the context of recent changes to the CSCW conference that may have
the effect of upsetting the preference for contributions from the core.
| arxiv topic:cs.DL cs.SI physics.soc-ph |
arxiv_dataset-44901307.7272 | Estimation of high-resolution dust column density maps: Empirical model
fits
astro-ph.GA
Sub-millimetre dust emission is an important tracer of density N of dense
interstellar clouds. One has to combine surface brightness information at
different spatial resolutions, and specific methods are needed to derive N at a
resolution higher than the lowest resolution of the observations. Some methods
have been discussed in the literature, including a method (in the following,
method B) that constructs the N estimate in stages, where the smallest spatial
scales being derived only use the shortest wavelength maps. We propose simple
model fitting as a flexible way to estimate high-resolution column density
maps. Our goal is to evaluate the accuracy of this procedure and to determine
whether it is a viable alternative for making these maps. The new method
consists of model maps of column density (or intensity at a reference
wavelength) and colour temperature. The model is fitted using Markov chain
Monte Carlo (MCMC) methods, comparing model predictions with observations at
their native resolution. We analyse simulated surface brightness maps and
compare its accuracy with method B and the results that would be obtained using
high-resolution observations without noise. The new method is able to produce
reliable column density estimates at a resolution significantly higher than the
lowest resolution of the input maps. Compared to method B, it is relatively
resilient against the effects of noise. The method is computationally more
demanding, but is feasible even in the analysis of large Herschel maps. The
proposed empirical modelling method E is demonstrated to be a good alternative
for calculating high-resolution column density maps, even with considerable
super-resolution. Both methods E and B include the potential for further
improvements, e.g., in the form of better a priori constraints.
| arxiv topic:astro-ph.GA |
arxiv_dataset-44911307.7372 | Linking electromagnetic and gravitational radiation in coalescing binary
neutron stars
gr-qc astro-ph.HE
We expand on our study of the gravitational and electromagnetic emissions
from the late stage of an inspiraling neutron star binary as presented in Ref.
\cite{Palenzuela:2013hu}. Interactions between the stellar magnetospheres,
driven by the extreme dynamics of the merger, can yield considerable outflows.
We study the gravitational and electromagnetic waves produced during the
inspiral and merger of a binary neutron star system using a full relativistic,
resistive MHD evolution code. We show that the interaction between the stellar
magnetospheres extracts kinetic energy from the system and powers radiative
Poynting flux and heat dissipation. These features depend strongly on the
configuration of the initial stellar magnetic moments. Our results indicate
that this power can strongly outshine pulsars in binaries and have a
distinctive angular and time-dependent pattern. Our discussion provides more
detail than Ref. \cite{Palenzuela:2013hu}, showing clear evidence of the
different effects taking place during the inspiral. Our simulations include a
few milliseconds after the actual merger and study the dynamics of the magnetic
fields during the formation of the hypermassive neutron star. We also briefly
discuss the possibility of observing such emissions.
| arxiv topic:gr-qc astro-ph.HE |
arxiv_dataset-44921307.7472 | Improved Service Delivery and Cost Effective Framework for e-Governance
in India
cs.CY
In current era, the involvement of technologies like virtualization,
consolidation and cloud computing, and adoption of free and open source
software in designing and deploying e-governance that can reduce the total cost
associated with and hence the financial burden abide by the state and central
governments. The success of any e-governance project depends upon its
utilization by the intended group and so there accessibility needs to be
enhanced drastically by reengineered framework. Here, we design an Improved
Service Delivery and Cost Effective Framework for e-Governance that will be
useful for success of e-governance projects and the delivery mechanism in India
by using free and open access software for development and deployment of
e-governance applications, virtualization and consolidation techniques for
management of e-services and cloud computing for enhancing the accessibility of
services.
| arxiv topic:cs.CY |
arxiv_dataset-44931307.7572 | The algebra $U_q({\mathfrak{sl}_2})$ in disguise
math.RT math.QA
We discuss a connection between the algebra $U_q({\mathfrak{sl}_2})$ and the
tridiagonal pairs of $q$-Racah type. To describe the connection, let $x,y^{\pm
1},z$ denote the equitable generators for $U_q({\mathfrak{sl}_2})$. Let
$U^\vee_q$ denote the subalgebra of $U_q({\mathfrak{sl}_2})$ generated by
$x,y^{-1},z$. Using a tridiagonal pair of $q$-Racah type we construct two
finite-dimensional $U^\vee_q$-modules. The constructions yield two nonstandard
presentations of $U^\vee_q$ by generators and relations. These presentations
are investigated in detail.
| arxiv topic:math.RT math.QA |
arxiv_dataset-44941307.7672 | On some structures of Leibniz algebras
math.RA
Leibniz algebras are certain generalization of Lie algebras. In this paper we
survey the important results in Leibniz algebras which are analogs of
corresponding results in Lie algebras. In particular we highlight the
differences between Leibniz algebras and Lie algebras.
| arxiv topic:math.RA |
arxiv_dataset-44951307.7772 | Bulk Energization of Electrons in Solar Flares by Alfv\'en Waves
astro-ph.SR physics.plasm-ph
Bulk energization of electrons to $10\,-\,20\,$keV in solar flares is
attributed to dissipation of Alfv\'en waves that transport energy and potential
downward to an acceleration region near the chromosphere. The acceleration
involves the parallel electric field that develops in the limit of inertial
Alfv\'en waves (IAWs). A two-potential model for IAWs is used to relate the
parallel potential to the cross-field potential transported by the waves. We
identify a maximum parallel potential in terms of a maximum current density
that corresponds to the threshold for the onset of anomalous resistivity. This
maximum is of order $10\,$kV when the threshold is that for the Buneman
instability. We argue that this restricts the cross-field potential in an
Alfv\'en wave to about $10\,$kV. Effective dissipation requires a large number
of up- and down-current paths associated with multiple Alfv\'en waves. The
electron acceleration occurs in localized, transient, anomalously-conducting
regions (LTACRs) and is associated with the parallel electric field determined
by Ohm's law with an anomalous resistivity. We introduce an idealized model in
which the LTACRs are (upward-)current sheets, a few skin depths in thickness,
separated by much-larger regions of weaker return current. We show that this
model can account semi-quantitatively for bulk energization.
| arxiv topic:astro-ph.SR physics.plasm-ph |
arxiv_dataset-44961307.7872 | Generating functionals for guided self-organization
q-bio.NC nlin.AO
Time evolution equations for dynamical systems can often be derived from
generating functionals. Examples are Newton's equations of motion in classical
dynamics which can be generated within the Lagrange or the Hamiltonian
formalism. We propose that generating functionals for self-organizing complex
systems offer several advantages. Generating functionals allow to formulate
complex dynamical systems systematically and the results obtained are typically
valid for classes of complex systems, as defined by the type of their
respective generating functionals. The generated dynamical systems tend, in
addition, to be minimal, containing only few free and undetermined parameters.
We point out that two or more generating functionals may be used to define a
complex system and that multiple generating function may not, and should not,
be combined into a single overall objective function. We provide and discuss
examples in terms of adapting neural networks.
| arxiv topic:q-bio.NC nlin.AO |
arxiv_dataset-44971307.7972 | Generalization of the hypervirial and Feynman-Hellman theorems
math-ph hep-th math.MP quant-ph
Using well-known methods we generalize (hyper)virial theorems to case of
singular potential. Discussion is carried on for most general second order
differential equation, which involves all physically interesting cases, such as
Schr\"odinger and two-body Klein-Gordon equations with singular potentials.
Some physical consequences are discussed. The connection with Feynman-Hellmann
like theorems are also considered and some relevant differences are underlined.
| arxiv topic:math-ph hep-th math.MP quant-ph |
arxiv_dataset-44981307.8072 | Deep Chandra Observations of Abell 2199: the Interplay between
Merger-Induced Gas Motions and Nuclear Outbursts in a Cool Core Cluster
astro-ph.CO
We present new Chandra observations of Abell 2199 that show evidence of gas
sloshing due to a minor merger, as well as impacts of the radio source, 3C 338,
hosted by the central galaxy, NGC 6166, on the intracluster gas. The new data
are consistent with previous evidence of a Mach 1.46 shock 100" from the
cluster center, although there is still no convincing evidence for the expected
temperature jump. Other interpretations of this feature are possible, but none
is fully satisfactory. Large scale asymmetries, including enhanced X-ray
emission 200" southwest of the cluster center and a plume of low entropy,
enriched gas reaching 50" to the north of the center, are signatures of gas
sloshing induced by core passage of a merging subcluster about 400 Myr ago. An
association between the unusual radio ridge and low entropy gas are consistent
with this feature being the remnant of a former radio jet that was swept away
from the AGN by gas sloshing. A large discrepancy between the energy required
to produce the 100" shock and the enthalpy of the outer radio lobes of 3C 338
suggests that the lobes were formed by a more recent, less powerful radio
outburst. Lack of evidence for shocks in the central 10" indicates that the
power of the jet now is some two orders of magnitude smaller than when the 100"
shock was formed.
| arxiv topic:astro-ph.CO |
arxiv_dataset-44991307.8172 | Improved Median Polish Kriging for Simulation Metamodeling
cs.OH
In simulation, Median Polish Kriging is a technique used to predict
unobserved data points in two-dimensional space. The linear behavior of the
traditional Median Polish Kriging in the estimation of the mean function in a
high grid makes the interpolation of O(1) which has a low order in the
prediction and that leads to a high prediction error. Therefore, an improvement
in the estimation of the mean function has been introduced using Biharmonic
spline interpolation and the new technique has been called Improved Median
Polish Kriging (IMPK). The IMPK has been applied to the standard coal-ash data
in two-dimension. The novel method gave much better results according to the
cross validation results that were obtained when compared with the traditional
Median Polish Kriging.
| arxiv topic:cs.OH |
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