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arxiv_dataset-42001304.0867 | Cylindrical model structures
math.CT math.AT
We build a model structure from the simple point of departure of a structured
interval in a monoidal category - more generally, a structured cylinder and a
structured co-cylinder in a category.
| arxiv topic:math.CT math.AT |
arxiv_dataset-42011304.0967 | Basic geometric proof of the relation between dimensionality of a
regular simplex and its dihedral angle
math.HO
The formula for the dihedral angle of the simplex of n dimensions,
arccos(1/n), is derived using classical geometry.
| arxiv topic:math.HO |
arxiv_dataset-42021304.1067 | Collective allocation of science funding: from funding agencies to
scientific agency
physics.soc-ph cs.DL
Public agencies like the U.S. National Science Foundation (NSF) and the
National Institutes of Health (NIH) award tens of billions of dollars in annual
science funding. How can this money be distributed as efficiently as possible
to best promote scientific innovation and productivity? The present system
relies primarily on peer review of project proposals. In 2010 alone, NSF
convened more than 15,000 scientists to review 55,542 proposals. Although
considered the scientific gold standard, peer review requires significant
overhead costs, and may be subject to biases, inconsistencies, and oversights.
We investigate a class of funding models in which all participants receive an
equal portion of yearly funding, but are then required to anonymously donate a
fraction of their funding to peers. The funding thus flows from one participant
to the next, each acting as if he or she were a funding agency themselves. Here
we show through a simulation conducted over large-scale citation data (37M
articles, 770M citations) that such a distributed system for science may yield
funding patterns similar to existing NIH and NSF distributions, but may do so
at much lower overhead while exhibiting a range of other desirable features.
Self-correcting mechanisms in scientific peer evaluation can yield an efficient
and fair distribution of funding. The proposed model can be applied in many
situations in which top-down or bottom-up allocation of public resources is
either impractical or undesirable, e.g. public investments, distribution
chains, and shared resource management.
| arxiv topic:physics.soc-ph cs.DL |
arxiv_dataset-42031304.1167 | Gravitational collapse in Ho\v{r}ava-Lifshitz theory
hep-th gr-qc
We study gravitational collapse of a spherical fluid in nonrelativistic
general covariant theory of the Ho\v{r}ava-Lifshitz gravity with the
projectability condition and an arbitrary coupling constant $\lambda$, where
$|\lambda - 1|$ characterizes the deviation of the theory from general
relativity in the infrared limit. The junction conditions across the surface of
a collapsing star are derived under the (minimal) assumption that the junctions
be mathematically meaningful in terms of distribution theory. When the
collapsing star is made of a homogeneous and isotropic perfect fluid, and the
external region is described by a stationary spacetime, the problem reduces to
the matching of six independent conditions. If the perfect fluid is
pressureless (a dust fluid), it is found that the matching is also possible. In
particular, in the case $\lambda = 1$, the external spacetime is described by
the Schwarzschild (anti-) de Sitter solution written in Painlev\'e-Gullstrand
coordinates. In the case $\lambda \not= 1$, the external spacetime is static
but not asymptotically flat. Our treatment can be easily generalized to other
versions of Ho\v{r}ava-Lifshitz gravity or, more generally, to any theory of
higher-order derivative gravity.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-42041304.1267 | Analysis of bibliometric indicators for individual scholars in a large
data set
physics.soc-ph cs.DL
Citation numbers and other quantities derived from bibliographic databases
are becoming standard tools for the assessment of productivity and impact of
research activities. Though widely used, still their statistical properties
have not been well established so far. This is especially true in the case of
bibliometric indicators aimed at the evaluation of individual scholars, because
large-scale data sets are typically difficult to be retrieved. Here, we take
advantage of a recently introduced large bibliographic data set, Google Scholar
Citations, which collects the entire publication record of individual scholars.
We analyze the scientific profile of more than 30,000 researchers, and study
the relation between the h-index, the number of publications and the number of
citations of individual scientists. While the number of publications of a
scientist has a rather weak relation with his/her h-index, we find that the
h-index of a scientist is strongly correlated with the number of citations that
she/he has received so that the number of citations can be effectively be used
as a proxy of the h-index. Allowing for the h-index to depend on both the
number of citations and the number of publications, we find only a minor
improvement.
| arxiv topic:physics.soc-ph cs.DL |
arxiv_dataset-42051304.1367 | The Effects of Inhomogeneities within Colliding Flows on the Formation
and Evolution of Molecular Clouds
astro-ph.GA
Observational evidence from local star-forming regions mandates that star
formation occurs shortly after, or even during, molecular cloud formation.
Models of the formation of molecular clouds in large-scale converging flows
have identified the physical mechanisms driving the necessary rapid
fragmentation. They also point to global gravitational collapse driving
supersonic turbulence in molecular clouds. Previous cloud formation models have
focused on turbulence generation, gravitational collapse, magnetic fields, and
feedback. Here, we explore the effect of structure in the flow on the resulting
clouds and the ensuing gravitational collapse. We compare two extreme cases,
one with a collision between two smooth streams, and one with streams
containing small clumps. We find that structured converging flows lead to a
delay of local gravitational collapse ("star formation"). Thus, more gas has
time to accumulate, eventually leading to a strong global collapse, and thus to
a high star formation rate. Uniform converging flows fragment hydrodynamically
early on, leading to the rapid onset of local gravitational collapse and an
overall low sink formation rate.
| arxiv topic:astro-ph.GA |
arxiv_dataset-42061304.1467 | Dimension Independent Matrix Square using MapReduce
cs.DS cs.DC math.SP
We compute the singular values of an $m \times n$ sparse matrix $A$ in a
distributed setting, without communication dependence on $m$, which is useful
for very large $m$. In particular, we give a simple nonadaptive sampling scheme
where the singular values of $A$ are estimated within relative error with
constant probability. Our proven bounds focus on the MapReduce framework, which
has become the de facto tool for handling such large matrices that cannot be
stored or even streamed through a single machine.
On the way, we give a general method to compute $A^TA$. We preserve singular
values of $A^TA$ with $\epsilon$ relative error with shuffle size
$O(n^2/\epsilon^2)$ and reduce-key complexity $O(n/\epsilon^2)$. We further
show that if only specific entries of $A^TA$ are required and $A$ has
nonnegative entries, then we can reduce the shuffle size to $O(n \log(n) / s)$
and reduce-key complexity to $O(\log(n)/s)$, where $s$ is the minimum cosine
similarity for the entries being estimated. All of our bounds are independent
of $m$, the larger dimension. We provide open-source implementations in Spark
and Scalding, along with experiments in an industrial setting.
| arxiv topic:cs.DS cs.DC math.SP |
arxiv_dataset-42071304.1567 | Blind Men and the Elephant: Detecting Evolving Groups In Social News
cs.SI cs.IR physics.soc-ph
We propose an automated and unsupervised methodology for a novel
summarization of group behavior based on content preference. We show that graph
theoretical community evolution (based on similarity of user preference for
content) is effective in indexing these dynamics. Combined with text analysis
that targets automatically-identified representative content for each
community, our method produces a novel multi-layered representation of evolving
group behavior. We demonstrate this methodology in the context of political
discourse on a social news site with data that spans more than four years and
find coexisting political leanings over extended periods and a disruptive
external event that lead to a significant reorganization of existing patterns.
Finally, where there exists no ground truth, we propose a new evaluation
approach by using entropy measures as evidence of coherence along the evolution
path of these groups. This methodology is valuable to designers and managers of
online forums in need of granular analytics of user activity, as well as to
researchers in social and political sciences who wish to extend their inquiries
to large-scale data available on the web.
| arxiv topic:cs.SI cs.IR physics.soc-ph |
arxiv_dataset-42081304.1667 | Spinning dark matter halos promote bar formation
astro-ph.CO
Stellar bars are the most common non-axisymmetric structures in galaxies and
their impact on the evolution of disc galaxies at all cosmological times can be
significant. Classical theory predicts that stellar discs are stabilized
against bar formation if embedded in massive spheroidal dark matter halos.
However, dark matter halos have been shown to facilitate the growth of bars
through resonant gravitational interaction. Still, it remains unclear why some
galaxies are barred and some are not. In this study, we demonstrate that
co-rotating (i.e., in the same sense as the disc rotating) dark matter halos
with spin parameters in the range of $0 \le \lambda_{\mathrm{dm}} \le 0.07$ -
which are a definite prediction of modern cosmological models - promote the
formation of bars and boxy bulges and therefore can play an important role in
the formation of pseudobulges in a kinematically hot dark matter dominated disc
galaxies. We find continuous trends for models with higher halo spins: bars
form more rapidly, the forming slow bars are stronger, and the final bars are
longer. After 2 Gyrs of evolution, the amplitude of the bar mode in a model
with $\lambda_{\mathrm{dm}} = 0.05$ is a factor of ~6 times higher, A_2/A_0 =
0.23, than in the non-rotating halo model. After 5 Gyrs, the bar is ~ 2.5 times
longer. The origin of this trend is that more rapidly spinning (co-rotating)
halos provide a larger fraction of trailing dark matter particles that lag
behind the disc bar and help growing the bar by taking away its angular
momentum by resonant interactions. A counter-rotating halo suppresses the
formation of a bar in our models. We discuss potential consequences for forming
galaxies at high-redshift and present day low mass galaxies which have
converted only a small fraction of their baryons into stars.
| arxiv topic:astro-ph.CO |
arxiv_dataset-42091304.1767 | On time and space double-slit experiments
quant-ph
Time double-slit interference experiments have been achieved and presented as
complementary to spatial double-slit interference experiments, providing a
further confirmation of the wave-particle duality. Numerical solutions of the
free particle time dependent Schr\"odinger equation were presented as
explanation of the experimental results, but have been objected to on the basis
that the standard non relativistic quantum theory does not have the property of
coherence in time. In this note the theoretical and experimental results are
derived in a schematic but analytic solution of the TDSE with appropiate
initial boundary conditions. The particular boundary conditions are justified
by the experimental setups that actually result in having only a single
electron at any given time in the double-slit arrangement; and consequently
achieve the construction of double peak single electron wave packets. The
progressive complementarity of "which-path" ("which-time") information and
"space interference" ("oscillating time transient") pattern build up is also
exhibited.
| arxiv topic:quant-ph |
arxiv_dataset-42101304.1867 | Geometrical scaling in high energy collisions and its breaking
hep-ph
We analyze geometrical scaling (GS) in Deep Inelstic Scattering at HERA and
in pp collisions at the LHC energies and in NA61/SHINE experiment. We argue
that GS is working up to relatively large Bjorken $x \sim 0.1$. This allows to
study GS in negative pion multiplicity $p_{\rm T}$ distributions at NA61/SHINE
energies where clear sign of scaling violations is seen with growing rapidity
when one of the colliding partons has Bjorekn $x \ge 0.1$.
| arxiv topic:hep-ph |
arxiv_dataset-42111304.1967 | Deep and Wide Photometry of Two Open Clusters NGC 1245 and NGC 2506:
Dynamical Evolution and Halo
astro-ph.GA
We studied the structure of two old open clusters, NGC 1245 and NGC 2506,
from a wide and deep VI photometry data acquired using the CFH12K CCD camera at
CFHT. We devised a new method for assigning cluster membership probability to
individual stars using both spatial positions and positions in the
colour-magnitude diagram. From analyses of the luminosity functions at several
cluster-centric radii and the radial surface density profiles derived from
stars with different luminosity ranges, we found that the two clusters are
dynamically relaxed to drive significant mass segregation and evaporation of
some fraction of low-mass stars. There seems to be a signature of tidal tail in
NGC 1245 but the signal is too low to be confirmed.
| arxiv topic:astro-ph.GA |
arxiv_dataset-42121304.2067 | Relative variables of the exact fermion-antifermion bound state
wave-function in the Schwinger Model
hep-th
The exact Bethe-Salpeter amplitude for the fermion-antifermion bound state in
the Schwinger Model is investigated. The dependence on the relative time and
position in the center-of-mass frame in all contributing instanton sectors is
analyzed. The same is accomplished for the relative energy and momentum
variables. Several interesting properties of the amplitude are revealed. The
explicit threshold structure is demonstrated.
| arxiv topic:hep-th |
arxiv_dataset-42131304.2167 | Canonical transformations for fermions in superanalysis
math-ph math.MP
Canonical transformations (Bogoliubov transformations) for fermions with an
infinite number of degrees of freedom are studied within a calculus of
superanalysis. A continuous representation of the orthogonal group is
constructed on a Grassmann module extension of the Fock space. The pull-back of
these operators to the Fock space yields a unitary ray representation of the
group that implements the Bogoliubov transformations.
| arxiv topic:math-ph math.MP |
arxiv_dataset-42141304.2267 | Reentrant cluster glass behavior in La2CoMnO6 nanoparticles
cond-mat.mtrl-sci
Magnetic study on La2CoMnO6 nanoparticles revealed multiple magnetic
transitions at 218 K, 135 K and below 38 K and the nature of the low
temperature transition was unclear [J Appl Phys 111, 024102 2012]. Presence of
mixed valance states of Co and Mn has been confirmed from the XPS measurement
and its presence along with antisite disorder affects in reducing the
saturation magnetization of the nanoparticles. The zero field cooled and field
cooled bifurcation in dc magnetization, relaxation in zero field cooled
magnetization and large enhancement in coercive field below the glassy
temperature has been discussed. Frequency dependence of ac susceptibility using
power law has revealed cluster glass behavior. Further, the dc field
superimposed on ac susceptibility and absence of memory effect in ac
susceptibility has suggested the existence of non interacting clusters
comprising of competing interactions below 38 K. Competing magnetic
interactions due to the presence of mixed valances and antisite disorder found
to establish a reentered cluster glassy state in the nanoparticles.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-42151304.2367 | Utility-Based Control for Computer Vision
cs.CV cs.AI cs.SY
Several key issues arise in implementing computer vision recognition of world
objects in terms of Bayesian networks. Computational efficiency is a driving
force. Perceptual networks are very deep, typically fifteen levels of
structure. Images are wide, e.g., an unspecified-number of edges may appear
anywhere in an image 512 x 512 pixels or larger. For efficiency, we dynamically
instantiate hypotheses of observed objects. The network is not fixed, but is
created incrementally at runtime. Generation of hypotheses of world objects and
indexing of models for recognition are important, but they are not considered
here [4,11]. This work is aimed at near-term implementation with parallel
computation in a radar surveillance system, ADRIES [5, 15], and a system for
industrial part recognition, SUCCESSOR [2]. For many applications, vision must
be faster to be practical and so efficiently controlling the machine vision
process is critical. Perceptual operators may scan megapixels and may require
minutes of computation time. It is necessary to avoid unnecessary sensor
actions and computation. Parallel computation is available at several levels of
processor capability. The potential for parallel, distributed computation for
high-level vision means distributing non-homogeneous computations. This paper
addresses the problem of task control in machine vision systems based on
Bayesian probability models. We separate control and inference to extend the
previous work [3] to maximize utility instead of probability. Maximizing
utility allows adopting perceptual strategies for efficient information
gathering with sensors and analysis of sensor data. Results of controlling
machine vision via utility to recognize military situations are presented in
this paper. Future work extends this to industrial part recognition for
SUCCESSOR.
| arxiv topic:cs.CV cs.AI cs.SY |
arxiv_dataset-42161304.2467 | Evolutionary Design of Digital Circuits Using Genetic Programming
cs.NE
For simple digital circuits, conventional method of designing circuits can
easily be applied. But for complex digital circuits, the conventional method of
designing circuits is not fruitfully applicable because it is time-consuming.
On the contrary, Genetic Programming is used mostly for automatic program
generation. The modern approach for designing Arithmetic circuits, commonly
digital circuits, is based on Graphs. This graph-based evolutionary design of
arithmetic circuits is a method of optimized designing of arithmetic circuits.
In this paper, a new technique for evolutionary design of digital circuits is
proposed using Genetic Programming (GP) with Subtree Mutation in place of
Graph-based design. The results obtained using this technique demonstrates the
potential capability of genetic programming in digital circuit design with
limited computer algorithms. The proposed technique, helps to simplify and
speed up the process of designing digital circuits, discovers a variation in
the field of digital circuit design where optimized digital circuits can be
successfully and effectively designed.
| arxiv topic:cs.NE |
arxiv_dataset-42171304.2567 | Discrepancies in the Monte Carlo simulations of propagation of
ultra-high energy cosmic-ray photons in the geomagnetic field
astro-ph.IM astro-ph.HE
The discrepancies in the results produced by the two most commonly used Monte
Carlo programs for simulation of propagation of ultra-high energy cosmic ray
photons in the presence of the geomagnetic field are presented. Although
photons have not yet been discovered in the cosmic ray flux at highest
energies, the capabilities of the present cosmic ray detectors make their
discovery possible, according to the predictions of conventional models, within
the next few years. It is therefore necessary to have a reliable and well
maintained software for relevant simulations. The results of this paper are
important for simulations of propagation of photons at energies above 10^19 eV.
Photons of such high energies might interact with the geomagnetic field giving
rise to a cascade of particles even above the atmosphere. This effect is called
a "preshower effect". The preshower effect is important for air shower
evolution and has to be accounted for in full Monte Carlo simulations of
propagation of highest energy cosmic-ray photons. In this paper we compare the
two most frequently used Monte Carlo codes for preshower simulations:
PRESHOWER, used as a stand-alone program or as a part of CORSIKA, and MaGICS,
used as a part of AIRES.
| arxiv topic:astro-ph.IM astro-ph.HE |
arxiv_dataset-42181304.2667 | Measurement-based classical computation
quant-ph
Measurement-based quantum computation (MBQC) is a model of quantum
computation, in which computation proceeds via adaptive single qubit
measurements on a multi-qubit quantum state. It is computationally equivalent
to the circuit model. Unlike the circuit model, however, its classical analog
is little studied. Here we present a classical analog of MBQC whose
computational complexity presents a rich structure. To do so, we identify
uniform families of quantum computations (refining the circuits introduced by
Bremner, Jozsa and Shepherd in Proc. R. Soc. A 467, 459 (2011)) whose output is
likely hard to exactly simulate (sample) classically. We demonstrate that these
circuit families can be efficiently implemented in the MBQC model without
adaptive measurement, and thus can be achieved in a classical analog of MBQC
whose resource state is a probability distribution which has been created
quantum mechanically. Such states (by definition) violate no Bell inequality,
but nevertheless exhibit non-classicality when used as a computational resource
- an imprint of their quantum origin.
| arxiv topic:quant-ph |
arxiv_dataset-42191304.2767 | The Higgs mass from a String-Theoretic Perspective
hep-th hep-ph
The Higgs quartic coupling has now been indirectly measured at the
electroweak scale. Assuming no new low-scale physics, its running is known and,
together with gauge and Yukawa couplings, it is a crucial new piece of
information constraining UV completions of the Standard Model. In particular,
supersymmetry broken at an intermediate or high energy scale with tan(beta)=1
(i.e. lambda=0) is consistent with present data and has an independent
theoretical appeal. We analyze the possible string-theoretic motivations for
tan(beta)=1 (including both the shift-symmetry and the more economical variant
of a Z_2 symmetry) in a Higgs sector realized on either 6- or 7-branes. We
identify specific geometries where lambda ~ 0 may arise naturally and specify
the geometrical problems which need to be solved to determine its precise value
in the generic case. We then analyze the radiative corrections to lambda.
Finally we show that, in contrast to naive expectations, lambda<0 at the SUSY
breaking scale is also possible. Specifically, string theory may produce an
MSSM plus chiral singlet at a very high scale, which immediately breaks to a
non-SUSY Standard Model with lambda<0. This classically unstable theory then
becomes metastable through running towards the IR.
| arxiv topic:hep-th hep-ph |
arxiv_dataset-42201304.2867 | Guidelines to the Problem of Location Management and Database
Architecture for the Next Generation Mobile Networks
cs.NI cs.DB
In near future, anticipated large number of mobile users may introduce very
large centralized databases and increase end-to-end delays in location
registration and call delivery on HLR-VLR database and will become infeasible.
After observing several problems we propose some guidelines. Multitree
distributed database, high throughput index structure, memory oriented database
organization are used. Location management guidelines for moving user in
overlapping network, neighbor discovery protocol (NDP), and global roaming rule
are adopted. Analytic model and examples are presented to evaluate the
efficiency of proposed guidelines.
| arxiv topic:cs.NI cs.DB |
arxiv_dataset-42211304.2967 | Log-majorization of the moduli of the eigenvalues of a matrix polynomial
by tropical roots
math.SP math.NA
We show that the sequence of moduli of the eigenvalues of a matrix polynomial
is log-majorized, up to universal constants, by a sequence of "tropical roots"
depending only on the norms of the matrix coefficients. These tropical roots
are the non-differentiability points of an auxiliary tropical polynomial, or
equivalently, the opposites of the slopes of its Newton polygon. This extends
to the case of matrix polynomials some bounds obtained by Hadamard, Ostrowski
and P\'olya for the roots of scalar polynomials. We also obtain new bounds in
the scalar case, which are accurate for "fewnomials" or when the tropical roots
are well separated.
| arxiv topic:math.SP math.NA |
arxiv_dataset-42221304.3067 | Precession-tracking coordinates for simulations of
compact-object-binaries
gr-qc
Binary black hole simulations with black hole excision using spectral methods
require a coordinate transformation into a co-rotating coordinate system where
the black holes are essentially at rest. This paper presents and discusses two
coordinate transformations that are applicable to precessing binary systems,
one based on Euler angles, the other on quaternions. Both approaches are found
to work well for binaries with moderate precession, i.e. for cases where the
orientation of the orbital plane changes by much less than 90 degrees. For
strong precession, performance of the Euler-angle parameterization
deteriorates, eventually failing for a 90 degree change in orientation because
of singularities in the parameterization ("gimbal lock"). In contrast, the
quaternion representation is invariant under an overall rotation, and handles
any orientation of the orbital plane as well as the Euler-angle technique
handles non-precessing binaries.
| arxiv topic:gr-qc |
arxiv_dataset-42231304.3167 | Dynamics of the solar tachocline III: Numerical solutions of the Gough
and McIntyre model
astro-ph.SR
We present the first numerical simulations of the solar interior to exhibit a
tachocline consistent with the Gough and McIntyre (1998) model. We find
nonlinear, axisymmetric, steady-state numerical solutions in which: (1) a
large-scale primordial field is confined within the radiation zone by
downwelling meridional flows that are gyroscopically pumped in the convection
zone (2) the radiation zone is in almost-uniform rotation, with a rotation rate
consistent with observations (3) the bulk of the tachocline is magnetic free,
in thermal-wind balance and in thermal equilibrium and (4) the interaction
between the field and the flows takes place within a very thin magnetic
boundary layer, the tachopause, located at the bottom of the tachocline. We
show that the thickness of the tachocline scales with the amplitude of the
meridional flows exactly as predicted by Gough and McIntyre. We also determine
the parameter conditions under which such solutions can be obtained, and
provide a simple explanation for the failure of previous numerical attempts at
reproducing the Gough and McIntyre model. Finally, we discuss the implications
of our findings for future numerical models of the solar interior, and for
future observations of the Sun and other stars.
| arxiv topic:astro-ph.SR |
arxiv_dataset-42241304.3267 | Current Status and Future Potential of Nuclide Discoveries
nucl-ex nucl-th
Presently about 3000 different nuclei are known with about another 3000-4000
predicted to exist. A review of the discovery of the nuclei, the present status
and the possibilities for future discoveries are presented.
| arxiv topic:nucl-ex nucl-th |
arxiv_dataset-42251304.3367 | Analysis of a rate-adaptive reconciliation protocol and the effect of
the leakage on the secret key rate
quant-ph cs.IT math.IT
Quantum key distribution performs the trick of growing a secret key in two
distant places connected by a quantum channel. The main reason is that the
legitimate users can bound the information gathered by the eavesdropper. In
practical systems, whether because of finite resources or external conditions,
the quantum channel is subject to fluctuations. A rate adaptive information
reconciliation protocol, that adapts to the changes in the communication
channel, is then required to minimize the leakage of information in the
classical postprocessing.
We consider here the leakage of a rate-adaptive information reconciliation
protocol. The length of the exchanged messages is larger than that of an
optimal protocol; however, we prove that the min-entropy reduction is limited.
The simulation results, both on the asymptotic and in the finite-length regime,
show that this protocol allows to increase the amount of distillable secret
key.
| arxiv topic:quant-ph cs.IT math.IT |
arxiv_dataset-42261304.3467 | An effective network reduction approach to find the dynamical repertoire
of discrete dynamic networks
q-bio.MN cond-mat.dis-nn physics.bio-ph
Discrete dynamic models are a powerful tool for the understanding and
modeling of large biological networks. Although a lot of progress has been made
in developing analysis tools for these models, there is still a need to find
approaches that can directly relate the network structure to its dynamics. Of
special interest is identifying the stable patterns of activity, i.e., the
attractors of the system. This is a problem for large networks, because the
state space of the system increases exponentially with network size. In this
work we present a novel network reduction approach that is based on finding
network motifs that stabilize in a fixed state. Notably, we use a topological
criterion to identify these motifs. Specifically, we find certain types of
strongly connected components in a suitably expanded representation of the
network. To test our method we apply it to a dynamic network model for a type
of cytotoxic T cell cancer and to an ensemble of random Boolean networks of
size up to 200. Our results show that our method goes beyond reducing the
network and in most cases can actually predict the dynamical repertoire of the
nodes (fixed states or oscillations) in the attractors of the system.
| arxiv topic:q-bio.MN cond-mat.dis-nn physics.bio-ph |
arxiv_dataset-42271304.3567 | Growth of balls in the universal cover of surfaces and graphs
math.DG
In this paper, we prove uniform lower bounds on the volume growth of balls in
the universal covers of Riemannian surfaces and graphs. More precisely, there
exists a constant $\delta>0$ such that if $(M,hyp)$ is a closed hyperbolic
surface and $h$ another metric on $M$ with $\area(M,h)\leq \delta \area(M,hyp)$
then for every radius $R\geq 1$ the universal cover of $(M,h)$ contains an
$R$-ball with area at least the area of an $R$-ball in the hyperbolic plane.
This positively answers a question of L. Guth for surfaces. We also prove an
analog theorem for graphs.
| arxiv topic:math.DG |
arxiv_dataset-42281304.3667 | Chaos on the conveyor belt
nlin.CD physics.class-ph physics.comp-ph physics.pop-ph
The dynamics of a spring-block train placed on a moving conveyor belt is
investigated both by simple experiments and computer simulations. The first
block is connected by spring to an external static point, and due to the
dragging effect of the belt the blocks undergo complex stick-slip dynamics. A
qualitative agreement with the experimental results can only be achieved by
taking into account the spatial inhomogeneity of the friction force on the
belt's surface, modeled as noise. As a function of the velocity of the conveyor
belt and the noise strength, the system exhibits complex, self-organized
critical, sometimes chaotic dynamics and phase transition-like behavior. Noise
induced chaos and intermittency is also observed. Simulations suggest that the
maximum complexity of the dynamical states is achieved for a relatively small
number of blocks, around five.
| arxiv topic:nlin.CD physics.class-ph physics.comp-ph physics.pop-ph |
arxiv_dataset-42291304.3767 | A Taxonomy of Performance Assurance Methodologies and its Application in
High Performance Computer Architectures
cs.PF
This paper presents a systematic approach to the complex problem of high
confidence performance assurance of high performance architectures based on
methods used over several generations of industrial microprocessors. A taxonomy
is presented for performance assurance through three key stages of a product
life cycle-high level performance, RTL performance, and silicon performance.
The proposed taxonomy includes two components-independent performance assurance
space for each stage and a correlation performance assurance space between
stages. It provides a detailed insight into the performance assurance space in
terms of coverage provided taking into account capabilities and limitations of
tools and methodologies used at each stage. An application of the taxonomy to
cases described in the literature and to high performance Intel architectures
is shown. The proposed work should be of interest to manufacturers of high
performance microprocessor/chipset architectures and has not been discussed in
the literature.
| arxiv topic:cs.PF |
arxiv_dataset-42301304.3867 | Demazure Character Formulas for Generalized Kac--Moody Algebras
math.RT math.QA
For a dominant integral weight $lambda $, we introduce a family of $U_q ^+
(mathfrak{g})$-submodules $V_w (lambda)$ of the irreducible highest weight $U_q
(mathfrak{g})$-module $V(lambda)$ of highest weight $lambda $ for a generalized
Kac--Moody algebra $mathfrak{g}$. We prove that the module $V_w (lambda)$ is
spanned by its global basis, and then give a character formula for $V_w
(lambda)$, which generalizes the Demazure character formula for ordinary
Kac--Moody algebras.
| arxiv topic:math.RT math.QA |
arxiv_dataset-42311304.3967 | Phonon-induced dynamic resonance energy transfer
quant-ph cond-mat.mes-hall
In a network of interacting quantum systems achieving fast coherent energy
transfer is a challenging task. While quantum systems are susceptible to a wide
range of environmental factors, in many physical settings their interactions
with quantized vibrations, or phonons, of a supporting structure are the most
prevalent. This leads to noise and decoherence in the network, ultimately
impacting the energy-transfer process. In this work, we introduce a novel type
of coherent energy-transfer mechanism for quantum systems, where phonon
interactions are able to actually enhance the energy transfer. Here, a shared
phonon interacts with the systems and dynamically adjusts their resonances,
providing remarkable directionality combined with quantum speed- up. We call
this mechanism phonon-induced dynamic resonance energy transfer and show that
it enables long-range coherent energy transport even in highly disordered
systems.
| arxiv topic:quant-ph cond-mat.mes-hall |
arxiv_dataset-42321304.4067 | Square roots of Hamiltonian Diffeomorphisms
math.SG math.DS
In this article we prove that on any closed symplectic manifold there exists
an arbitrarily $C^\infty$-small Hamiltonian diffeomorphism not admitting a
square root.
| arxiv topic:math.SG math.DS |
arxiv_dataset-42331304.4167 | Intrinsic periodicity: the forgotten lesson of quantum mechanics
quant-ph hep-ph hep-th
Wave-particle duality, together with the concept of elementary particles, was
introduced by de Broglie in terms of intrinsically "periodic phenomena".
However, after nearly 90 years, the physical origin of such undulatory
mechanics remains unrevealed. We propose a natural realization of the de
Broglie "periodic phenomenon" in terms of harmonic vibrational modes associated
to space-time periodicities. In this way we find that, similarly to a vibrating
string or a particle in a box, the intrinsic recurrence imposed as a constraint
to elementary particles represents a fully consistent quantization condition.
The resulting classical cyclic dynamics formally match ordinary relativistic
Quantum Mechanics in both the canonical and Feynman formulations. Interactions
are introduced in a geometrodynamical way, similarly to general relativity, by
simply considering that variations of kinematical state can be equivalently
described in terms of modulations of space-time recurrences, as known from
undulatory mechanics. We present this novel quantization prescription from a
historical prospective.
| arxiv topic:quant-ph hep-ph hep-th |
arxiv_dataset-42341304.4267 | Inclusion Logic and Fixed Point Logic
cs.LO
We investigate the properties of Inclusion Logic, that is, First Order Logic
with Team Semantics extended with inclusion dependencies. We prove that
Inclusion Logic is equivalent to Greatest Fixed Point Logic, and we prove that
all union-closed first-order definable properties of relations are definable in
it. We also provide an Ehrenfeucht-Fra\"iss\'e game for Inclusion Logic, and
give an example illustrating its use.
| arxiv topic:cs.LO |
arxiv_dataset-42351304.4367 | Fast simulation method for parameter reconstruction in optical metrology
physics.optics physics.comp-ph
A method for automatic computation of parameter derivatives of numerically
computed light scattering signals is demonstrated. The finite-element based
method is validated in a numerical convergence study, and it is applied to
investigate the sensitivity of a scatterometric setup with respect to
geometrical parameters of the scattering target. The method can significantly
improve numerical performance of design optimization, parameter reconstruction,
sensitivity analysis, and other applications.
| arxiv topic:physics.optics physics.comp-ph |
arxiv_dataset-42361304.4467 | On the Glitch Evolution of Pulsars
astro-ph.HE astro-ph.SR
Observations of pulsar glitches remain a powerful tool for studying the
interior of neutron stars. Many of the observed glitch properties are shown to
result from the evolution of glitches in the different manifestations of
neutron stars. Specifically, the type of glitches associated with the Crab and
Vela pulsars are explained by this model. We are, also, able to adequately
account for the absence, or very low rate, of glitches among the youngest and
the very old pulsars.
| arxiv topic:astro-ph.HE astro-ph.SR |
arxiv_dataset-42371304.4567 | Multiple-Antenna Interference Network with Receive Antenna Joint
Processing and Real Interference Alignment
cs.IT math.IT
In this paper, the degrees of freedom (DoF) regions of constant coefficient
multiple antenna interference channels are investigated. First, we consider a
$K$-user Gaussian interference channel with $M_k$ antennas at transmitter $k$,
$1\le k\le K$, and $N_j$ antennas at receiver $j$, $1\le j\le K$, denoted as a
$(K,[M_k],[N_j])$ channel. Relying on a result of simultaneous Diophantine
approximation, a real interference alignment scheme with joint receive antenna
processing is developed. The scheme is used to obtain an achievable DoF region.
The proposed DoF region includes two previously known results as special cases,
namely 1) the total DoF of a $K$-user interference channel with $N$ antennas at
each node, $(K, [N], [N])$ channel, is $NK/2$; and 2) the total DoF of a $(K,
[M], [N])$ channel is at least $KMN/(M+N)$. We next explore
constant-coefficient interference networks with $K$ transmitters and $J$
receivers, all having $N$ antennas. Each transmitter emits an independent
message and each receiver requests an arbitrary subset of the messages.
Employing the novel joint receive antenna processing, the DoF region for this
set-up is obtained. We finally consider wireless X networks where each node is
allowed to have an arbitrary number of antennas. It is shown that the joint
receive antenna processing can be used to establish an achievable DoF region,
which is larger than what is possible with antenna splitting. As a special case
of the derived achievable DoF region for constant coefficient X network, the
total DoF of wireless X networks with the same number of antennas at all nodes
and with joint antenna processing is tight while the best inner bound based on
antenna splitting cannot meet the outer bound. Finally, we obtain a DoF region
outer bound based on the technique of transmitter grouping.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-42381304.4667 | The Baker-Campbell-Hausdorff formula and the Zassenhaus formula in
synthetic differential geometry
math.DG
After the torch of Anders Kock [Taylor series calculus for ring objects of
line type, Journal of Pure and Applied Algebra, 12 (1978), 271-293], we will
establish the Baker-Campbell-Hausdorff formula as well as the Zassenhaus
formula in the theory of Lie groups.
| arxiv topic:math.DG |
arxiv_dataset-42391304.4767 | Multiple solutions for a NLS equation with critical growth and magnetic
field
math.AP
In this paper, we are concerned with the multiplicity of nontrivial solutions
for the following class of complex problems $$ (-i\nabla - A(\mu x))^{2}u= \mu
|u|^{q-2}u + |u|^{2^{*}-2}u \ \mbox{in} \ \Omega, \ \ \ \ u \in
H^{1}_{0}(\Omega,\mathbb{C}), $$ where $\Omega \subset \mathbb{R}^{N} (N \geq
4)$ is a bounded domain with smooth boundary. Using the Lusternik-Schnirelman
theory, we relate the number of solutions with the topology of $\Omega$.
| arxiv topic:math.AP |
arxiv_dataset-42401304.4867 | Multiplicative structures on algebraic K-theory
math.KT math.CT
Algebraic K-theory is the stable homotopy theory of homotopy theories, and it
interacts with algebraic structures accordingly. In particular, we prove the
Deligne Conjecture for algebraic K-theory.
| arxiv topic:math.KT math.CT |
arxiv_dataset-42411304.4967 | An Emerging Coherent Picture of Red Supergiant Supernova Explosions
astro-ph.CO
Three lines of evidence indicate that in the most common type of core
collapse supernovae, the energy deposited in the ejecta by the exploding core
is approximately proportional to the progenitor mass cubed. This results stems
from an observed uniformity of light curve plateau duration, a correlation
between mass and ejecta velocity, and the known correlation between luminosity
and velocity. This result ties in analytical and numerical models together with
observations, providing us with clues as to the mechanism via which the
explosion of the core deposits a small fraction of its energy into the hurled
envelope.
| arxiv topic:astro-ph.CO |
arxiv_dataset-42421304.5067 | Trees of manifolds as boundaries of spaces and groups
math.GR math.GT
We show that trees of manifolds, the topological spaces introduced by
Jakobsche, appear as boundaries at infinity of various spaces and groups. In
particular, they appear as Gromov boundaries of some hyperbolic groups, of
arbitrary dimension, obtained by the procedure of strict hyperbolization. We
also recognize these spaces as boundaries of arbitrary Coxeter groups with
manifold nerves, and as Gromov boundaries of the fundamental groups of singular
spaces obtained from some finite volume hyperbolic manifolds by cutting off
their cusps and collapsing the resulting boundary tori to points.
| arxiv topic:math.GR math.GT |
arxiv_dataset-42431304.5167 | Chiral Y-junction of Luttinger liquid wires at strong coupling:
fermionic representation
cond-mat.str-el
We calculate the conductances of a three-terminal junction set-up of spinless
Luttinger liquid wires threaded by a magnetic flux, allowing for different
interaction strength g_3 != g in the third wire. We employ the fermionic
representation in the scattering state picture, allowing for a direct
calculation of the linear response conductances, without the need of
introducing contact resistances at the connection points to the outer ideal
leads. The matrix of conductances is parametrized by three variables. For these
we derive coupled renormalization group (RG) equations, by summing up infinite
classes of contributions in perturbation theory. The resulting general
structure of the RG equations may be employed to describe junctions with an
arbitrary number of wires and arbitrary interaction strength in each wire. The
fixed point structure of these equations (for the chiral Y-junction) is
analyzed in detail. For repulsive interaction (g,g_3>0) there is only one
stable fixed point, corresponding to the complete separation of the wires. For
attractive interaction (g<0 and/or g_3<0) four fixed points are found, the
stability of which depends on the interaction strength. We confirm our previous
weak-coupling result of lines of fixed points for special values of the
interaction parameters reaching into the strong coupling domain. We find new
fixed points not discussed before, even at the symmetric line g=g_3, at
variance with the results of Oshikawa et al. The pair tunneling phenomenon
conjectured by the latter authors is not found by us.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-42441304.5267 | Organization of strongly interacting directed polymer liquids in the
presence of stringent constraints
cond-mat.soft cond-mat.stat-mech
The impact of impenetrable obstacles on the energetics and equilibrium
structure of strongly repulsive directed polymers is investigated. As a result
of the strong interactions, regions of severe polymer depletion and excess are
found in the vicinity of the obstacle, and the associated free-energy cost is
found to scale quadratically with the average polymer density. The
polymer-polymer interactions are accounted for via a sequence of
transformations: from the 3D line liquid to a 2D fluid of Bose particles to a
2D composite fermion fluid and, finally, to a 2D one-component plasma. The
results presented here are applicable to a range of systems consisting of
noncrossing directed lines.
| arxiv topic:cond-mat.soft cond-mat.stat-mech |
arxiv_dataset-42451304.5367 | Molecular Environments of SNRs
astro-ph.GA astro-ph.HE
There are about 70 Galactic supernova remnants (SNRs) that are now confirmed
or suggested to be in physical contact with molecular clouds (MCs) with six
kinds of evidence of multiwavelength observations. Recent detailed CO-line
spectroscopic mappings of a series of SNRs reveal them to be in cavities of
molecular gas, implying the roles the progenitors may have played. We predict a
linear correlation between the wind bubble sizes of main-sequence OB stars in a
molecular environment and the stellar masses and discuss its implication for
supernova progenitors. The molecular environments of SNRs can serve as a good
probe for the gamma-rays arising from the hadronic interaction of the
accelerated protons, and this paper also discusses the gamma-ray emission from
MCs illuminated by diffusive protons that escape from SNR shocks.
| arxiv topic:astro-ph.GA astro-ph.HE |
arxiv_dataset-42461304.5467 | Spin nematic states in spin-1 antiferromagnets with easy-axis anisotropy
cond-mat.str-el
It is well known that spin nematic phases can appear in either frustrated
magnets or in those described by Hamiltonians with large exotic non-Heisenberg
terms like biquadratic exchange. We show in the present study that
non-frustrated spin-1 1D, 2D and 3D antiferromagnets with single-ion easy-axis
anisotropy can show nematic phases in strong magnetic field. For 1D case we
support our analytical results by numerical ones.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-42471304.5567 | Band-Like Transport in High Mobility Unencapsulated Single-Layer MoS2
Transistors
cond-mat.mes-hall cond-mat.mtrl-sci
Ultra-thin MoS2 has recently emerged as a promising two-dimensional
semiconductor for electronic and optoelectronic applications. Here, we report
high mobility (>60 cm2/Vs at room temperature) field-effect transistors that
employ unencapsulated single-layer MoS2 on oxidized Si wafers with a low level
of extrinsic contamination. While charge transport in the sub-threshold regime
is consistent with a variable range hopping model, monotonically decreasing
field-effect mobility with increasing temperature suggests band-like transport
in the linear regime. At temperatures below 100 K, temperature-independent
mobility is limited by Coulomb scattering, whereas, at temperatures above 100
K, phonon-limited mobility decreases as a power law with increasing
temperature.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-42481304.5667 | Counting Permutations Modulo Pattern-Replacement Equivalences for
Three-Letter Patterns
math.CO
We study a family of equivalence relations on $S_n$, the group of
permutations on $n$ letters, created in a manner similar to that of the Knuth
relation and the forgotten relation. For our purposes, two permutations are in
the same equivalence class if one can be reached from the other through a
series of pattern-replacements using patterns whose order permutations are in
the same part of a predetermined partition of $S_c$.
When the partition is of $S_3$ and has one nontrivial part and that part is
of size greater than two, we provide formulas for the number of classes created
in each previously unsolved case. When the partition is of $S_3$ and has two
nontrivial parts, each of size two (as do the Knuth and forgotten relations),
we enumerate the classes for $13$ of the $14$ unresolved cases. In two of these
cases, enumerations arise which are the same as those yielded by the Knuth and
forgotten relations. The reasons for this phenomenon are still largely a
mystery.
| arxiv topic:math.CO |
arxiv_dataset-42491304.5767 | Cohomology of n-ary-Nambu-Lie superalgebras and super_1 3-algebra
math.RA
The purpose of this paper is define the representation and the cohomology of
n-ary-Nambu-Lie superalgebras. Morever we study extensions and provide the
computation of the derivations and second cohomology group of super w_1
3-algebra
| arxiv topic:math.RA |
arxiv_dataset-42501304.5867 | Equivariant cycles and cancellation for motivic cohomology
math.AG math.AT
We introduce a Bredon motivic cohomology theory for smooth schemes defined
over a field and equipped with an action by a finite group. These cohomology
groups are defined for finite dimensional representations as the
hypercohomology of complexes of equivariant correspondences in the equivariant
Nisnevich topology. We generalize the theory of presheaves with transfers to
the equivariant setting and prove a Cancellation Theorem.
| arxiv topic:math.AG math.AT |
arxiv_dataset-42511304.5967 | Bayesian Nonparametric Estimation of Milky Way Model Parameters Using a
New Matrix-Variate Gaussian Process Based Method
stat.AP
In this paper we develop an inverse Bayesian approach to find the value of
the unknown model parameter vector that supports the real (or test) data, where
the data comprises measurements of a matrix-variate variable. The method is
illustrated via the estimation of the unknown Milky Way feature parameter
vector, using available test and simulated (training) stellar velocity data
matrices. The data is represented as an unknown function of the model
parameters, where this high-dimensional function is modelled using a
high-dimensional Gaussian Process (${\cal GP}$). The model for this function is
trained using available training data and inverted by Bayesian means, to
estimate the sought value of the model parameter vector at which the test data
is realised. We achieve a closed-form expression for the posterior of the
unknown parameter vector and the parameters of the invoked ${\cal GP}$, given
test and training data. We perform model fitting by comparing the observed data
with predictions made at different summaries of the posterior probability of
the model parameter vector. As a supplement, we undertake a leave-one-out cross
validation of our method.
| arxiv topic:stat.AP |
arxiv_dataset-42521304.6067 | Invasive Computing - Common Terms and Granularity of Invasion
cs.OS
Future MPSoCs with 1000 or more processor cores on a chip require new means
for resource-aware programming in order to deal with increasing imperfections
such as process variation, fault rates, aging effects, and power as well as
thermal problems. On the other hand, predictable program executions are
threatened if not impossible if no proper means of resource isolation and
exclusive use may be established on demand. In view of these problems and
menaces, invasive computing enables an application programmer to claim for
processing resources and spread computations to claimed processors dynamically
at certain points of the program execution.
Such decisions may be depending on the degree of application parallelism and
the state of the underlying resources such as utilization, load, and
temperature, but also with the goal to provide predictable program execution on
MPSoCs by claiming processing resources exclusively as the default and thus
eliminating interferences and creating the necessary isolation between multiple
concurrently running applications. For achieving this goal, invasive computing
introduces new programming constructs for resource-aware programming that
meanwhile, for testing purpose, have been embedded into the parallel computing
language X10 as developed by IBM using a library-based approach.
This paper presents major ideas and common terms of invasive computing as
investigated by the DFG Transregional Collaborative Research Centre TR89.
Moreoever, a reflection is given on the granularity of resources that may be
requested by invasive programs.
| arxiv topic:cs.OS |
arxiv_dataset-42531304.6167 | Convolution properties of some harmonic mappings in the right-half plane
math.CV
Dorff, proved in [2] that the convolution of two harmonic right-half plane
mappings is convex in the direction of real axis provided that the convolution
is locally univalent and sense preserving. Later, it was shown in [3] that the
condition of locally univalent and sense preserving can be dropped in some
special cases. In this paper, we generalize the main result from [3].
| arxiv topic:math.CV |
arxiv_dataset-42541304.6267 | LBT/LUCIFER near-infrared spectroscopy of PV Cephei. An outbursting
young stellar object with an asymmetric jet
astro-ph.SR
We present a detailed spectroscopic investigation of the young eruptive star
PV Cep, to improve our understanding of its nature and characterise its
circumstellar environment after its last outburst in 2004. The analysis of our
medium-resolution spectroscopy in the near-IR (0.9-2.35 um), collected in 2012
at the Large Binocular Telescope with the IR spectrograph LUCIFER, allows us to
infer the main stellar parameters (visual extinction, accretion luminosity,
mass accretion and ejection rates), and model the inner disc, jet, and wind.
The NIR spectrum displays several strong emission lines associated with
accretion/ejection activity and circumstellar environment. Our analysis shows
that the brightness of PV Cep is fading, as well as the mass accretion rate
(2x10^-7 Msun/yr^-1 in 2012 vs ~5x10^-6 Msun/yr^-1 in 2004), which is more than
one order of magnitude lower than in the outburst phase. Among the several
emission lines, only the [FeII] intensity increased after the outburst. The
observed [FeII] emission delineates blue- and red-shifted lobes, both with
high- and low-velocity components, which trace an asymmetric jet and wind,
respectively. The observed emission in the jet has a dynamical age of ~8 years,
indicating that it was produced during the last outburst. The mass ejection
rate in both lobes is 1.5x10^-7 Msun/yr^-1, approximately matching the high
accretion rate observed during and immediately after the outburst . The
observed jet/outflow asymmetries are consistent with an inhomogeneous medium.
Our modelling of the CO emission hints at a small-scale gaseous disc ring,
extending from ~0.2-0.4 AU to ~3 AU from the source, with an inner temperature
of ~3000 K. Our HI lines modelling indicates that most of the observed emission
comes from an expanding disc wind at Te=10000 K. The line profiles are strongly
affected by scattering, disc screening, and outflow self-absorption.
| arxiv topic:astro-ph.SR |
arxiv_dataset-42551304.6367 | CF2 White Paper: Status and Prospects of The VERITAS Indirect Dark
Matter Detection Program
astro-ph.HE
In this white paper, submitted as a part of Snowmass 2013 (subgroup CF2), we
examine the current status and future prospects of the VERITAS indirect dark
matter detection program. The VERITAS array of imaging atmospheric Cherenkov
telescopes (IACTs), sensitive in the 0.1-50 TeV regime, is in the process of
completing a multi-year program aimed at detecting signatures of neutralino
dark matter. This program is spread out over a range of astrophysical targets
which can potentially yield definitive signatures of neutralino
self-annihilation such as dwarf spheroidal galaxies (dSphs) and the center of
the Milky Way galaxy. While the program is still in progress, initial results
on dSphs have produced very competitive upper limits on the thermally averaged
cross-section of neutralino self-annihilation as well as strongly constraining
leptophillic dark matter models (such as those inferred from the PAMELA and AMS
positron fraction results). As the program continues over the next 5 years,
VERITAS observations will yield some of the strongest constraints available
from IACTs, pushing down the limit on the thermally averaged cross-section of
neutralino self-annihilation to the expected natural thermal relic scale.
| arxiv topic:astro-ph.HE |
arxiv_dataset-42561304.6467 | LP=>: Extending LP with a strong conditional operator
math.LO
We augment LP with a strong conditional operator, to yield a logic we call
"strong LP," or LP=>. The resulting logic can speak of consistency in more
discriminating ways, but introduces new possibilities for trivializing
paradoxes.
| arxiv topic:math.LO |
arxiv_dataset-42571304.6567 | Flexural mode of graphene on a substrate
cond-mat.mes-hall
Out of plane vibrations are suppressed in graphene layers placed on a
substrate. These modes, in suspended samples, are relevant for the
understanding of properties such as the resistivity, the thermal expansion
coefficient, and other. We present a general framework for the study of the
properties of out of plane modes in graphene on different substrates. We use
the model to estimate the substrate induced changes in the thermal expansion
coefficient, or in the temperature dependence of the resistivity.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-42581304.6667 | Competing effects of interactions in the adsorbed and activated states
on surface diffusion at low temperatures
cond-mat.stat-mech
The competing influence of two types of interactions on surface diffusion is
investigated: one of them, epsilon, acts between adsorbed particles, while the
other one, eta, between activated and adsorbed particles. To this end, a
specific lattice-gas model on a triangular, square, and hexagonal lattice is
considered with an attractive epsilon and an attractive or repulsive eta, both
restricted to nearest neighbors. For all three lattices the influence is
qualitatively the same. Namely, when eta is neglected, then epsilon is shown to
decelerate diffusion with a rate exponential in epsilon and inverse
temperature. Moreover, when eta is present and epsilon is fixed, then a
sufficiently attractive eta (relative to epsilon) accelerates diffusion
exponentially fast in eta and inverse temperature. However, quite surprisingly,
a repulsive or slightly attractive eta has practically no effect on diffusion.
Finally, when eta is set proportional to epsilon via a parameter $a$, surface
diffusion is exponentially accelerated (decelerated) for $a$ above (below) a
threshold value equal to 4, 5/4, and 7/8 for the three lattices. Thus, an eta
of strength comparable to epsilon is enough to boost diffusion on the square
and hexagonal lattices, while an eta of a rather large strength is needed for
the boost on the triangular lattice.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-42591304.6767 | Casimir Momentum of a Chiral Molecule in a Magnetic Field
quant-ph physics.chem-ph
In a classical description, a neutral, polarizable object acquires a kinetic
momentum when exposed to crossed electric and magnetic fields. In the presence
of only a magnetic field no such momentum exists classically, although it is
symmetry-allowed for an object lacking mirror symmetry. We perform a full QED
calculation to show that the quantum vacuum coupled to a chiral molecule
provides a kinetic "Casimir" momentum directed along the magnetic field,
proportional to its rotatory power and the fine structure constant.
| arxiv topic:quant-ph physics.chem-ph |
arxiv_dataset-42601304.6867 | Stability of the classical type of relative equilibria of a rigid body
in the J2 problem
astro-ph.EP
The motion of a point mass in the J2 problem is generalized to that of a
rigid body in a J2 gravity field. The linear and nonlinear stability of the
classical type of relative equilibria of the rigid body, which have been
obtained in our previous paper, are studied in the framework of geometric
mechanics with the second-order gravitational potential. Non-canonical
Hamiltonian structure of the problem, i.e., Poisson tensor, Casimir functions
and equations of motion, are obtained through a Poisson reduction process by
means of the symmetry of the problem. The linear system matrix at the relative
equilibria is given through the multiplication of the Poisson tensor and
Hessian matrix of the variational Lagrangian. Based on the characteristic
equation of the linear system matrix, the conditions of linear stability of the
relative equilibria are obtained. The conditions of nonlinear stability of the
relative equilibria are derived with the energy-Casimir method through the
projected Hessian matrix of the variational Lagrangian. With the stability
conditions obtained, both the linear and nonlinear stability of the relative
equilibria are investigated in details in a wide range of the parameters of the
gravity field and the rigid body. We find that both the zonal harmonic J2 and
the characteristic dimension of the rigid body have significant effects on the
linear and nonlinear stability. Similar to the classical attitude stability in
a central gravity field, the linear stability region is also consisted of two
regions that are analogues of the Lagrange region and the DeBra-Delp region
respectively. The nonlinear stability region is the subset of the linear
stability region in the first quadrant that is the analogue of the Lagrange
region. Our results are very useful for the studies on the motion of natural
satellites in our solar system.
| arxiv topic:astro-ph.EP |
arxiv_dataset-42611304.6967 | Tunnelling current through fractional quantum Hall interferometers
cond-mat.mes-hall cond-mat.str-el
We calculate the tunnelling current through a Fabry-P\'{e}rot interferometer
in the fractional quantum Hall regime. Within linear response theory (weak
tunnelling but arbitrary source-drain voltage) we find a general expression for
the current due to tunnelling of quasiparticles in terms of Carlson's $R$
function. Our result is valid for fractional quantum Hall states with an edge
theory consisting of a charged channel and any number of neutral channels, with
possibly different edge velocities and different chiralities. We analyse the
case with a single neutral channel in detail, which applies for instance to the
edge of the Moore-Read state. In addition we consider an asymmetric
interferometer with different edge lengths between the point contacts on
opposite edges, and we study the behaviour of the current as a function of
varying edge length. Recent experiments attempted to measure the Aharanov-Bohm
effect by changing the area inside the interferometer using a plunger gate.
Theoretical analyses of these experiments have so far not taken into account
the accompanying change in the edge lengths. We show that the tunnelling
current exhibits multiple osculations as a function of this edge length, with
frequencies proportional to the injected edge current and inversely
proportional to the edge velocities. In particular the edge velocities can be
measured by looking at the Fourier spectrum of the edge current. We provide a
numerical scheme to calculate and plot the $R$ function, and include sample
plots for a variety of edge states with parameter values which are
experimentally relevant.
| arxiv topic:cond-mat.mes-hall cond-mat.str-el |
arxiv_dataset-42621304.7067 | Detecting regularities on grammar-compressed strings
cs.DS
We solve the problems of detecting and counting various forms of regularities
in a string represented as a Straight Line Program (SLP). Given an SLP of size
$n$ that represents a string $s$ of length $N$, our algorithm compute all runs
and squares in $s$ in $O(n^3h)$ time and $O(n^2)$ space, where $h$ is the
height of the derivation tree of the SLP. We also show an algorithm to compute
all gapped-palindromes in $O(n^3h + gnh\log N)$ time and $O(n^2)$ space, where
$g$ is the length of the gap. The key technique of the above solution also
allows us to compute the periods and covers of the string in $O(n^2 h)$ time
and $O(nh(n+\log^2 N))$ time, respectively.
| arxiv topic:cs.DS |
arxiv_dataset-42631304.7167 | To see or not to see: Imaging surfactant coated nano--particles using
HIM and SEM
cond-mat.mtrl-sci
Nano--particles are of great interest in fundamental and applied research.
However, their accurate visualization is often difficult and the interpretation
of the obtained images can be complicated. We present a comparative scanning
electron microscopy and helium ion microscopy study of
cetyltrimethylammonium--bromide (CTAB) coated gold nano--rods. Using both
methods we show how the gold core as well as the surrounding thin CTAB shell
can selectively be visualized. This allows for a quantitative determination of
the dimensions of the gold core or the CTAB shell. The obtained CTAB shell
thickness of 1.0 nm--1.5 nm is in excellent agreement with earlier results
using more demanding and reciprocal space techniques.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-42641304.7267 | Polylogarithms, Multiple Zeta Values and Superstring Amplitudes
hep-th hep-ph math.NT
A formalism is provided to calculate tree amplitudes in open superstring
theory for any multiplicity at any order in the inverse string tension. We
point out that the underlying world-sheet disk integrals share substantial
properties with color-ordered tree amplitudes in Yang-Mills field theories. In
particular, we closely relate world-sheet integrands of open-string tree
amplitudes to the Kawai-Lewellen-Tye representation of supergravity amplitudes.
This correspondence helps to reduce the singular parts of world-sheet disk
integrals -including their string corrections- to lower-point results. The
remaining regular parts are systematically addressed by polylogarithm
manipulations.
| arxiv topic:hep-th hep-ph math.NT |
arxiv_dataset-42651304.7367 | Lambda Determinants
math.CO
In this paper we prove a homogenous generalization of the lambda determinant
formula of Mills, Robbins and Rumsey. In our formula the parameters depends on
two indices. Our result also extends a recent formula of Di Francesco.
| arxiv topic:math.CO |
arxiv_dataset-42661304.7467 | Heavy quark spin selection rules in meson-antimeson states
hep-ph hep-ex hep-lat nucl-th
In the heavy quark limit, we discuss the spin of the charm-anticharm pair
$J_{c\bar{c}}$ in an S-wave meson-antimeson molecule or resonance. One finds
two cases that $J_{c\bar{c}}$ cannot be 0: (a) $J=|j_2-j_4|-1$ or $J=j_2+j_4+1$
where $J$ is the total spin of the system and $j_2$ ($j_4$) is the total
angular momentum of the light degree of freedom in a charmed meson (antimeson);
(b) $J^C=1^+,2^-,3^+,...$, if the two different mesons belong to the same
doublet. The decays to spin-singlet charmonium states are suppressed when one
of the two conditions is satisfied. We discuss constrained decay properties for
selected systems.
| arxiv topic:hep-ph hep-ex hep-lat nucl-th |
arxiv_dataset-42671304.7567 | Integrable model for density-modulated quantum condensates: solitons
passing through a soliton lattice
cond-mat.quant-gas cond-mat.supr-con nlin.PS nlin.SI
An integrable model possessing inhomogeneous ground states is proposed as an
effective model of non-uniform quantum condensates such as supersolids and
Fulde--Ferrell--Larkin--Ovchinnikov superfluids. The model is a higher-order
analog of the nonlinear Schr\"odinger equation. We derive an $n$-soliton
solution via the inverse scattering theory with elliptic-functional background,
and reveal various kinds of soliton dynamics such as dark soliton billiards,
dislocations, gray solitons, and envelope solitons. We also provide the exact
bosonic and fermionic quasiparticle eigenstates and clarify their tunneling
phenomena. The solutions are expressed by a determinant of theta functions.
| arxiv topic:cond-mat.quant-gas cond-mat.supr-con nlin.PS nlin.SI |
arxiv_dataset-42681304.7667 | Magneto-Josephson effects and Majorana bound states in quantum wires
cond-mat.mes-hall cond-mat.supr-con
A prominent signature of Majorana bound states is the exotic Josephson
effects they produce, the classic example being a fractional Josephson current
with 4\pi periodicity in the phase difference across the junction. Recent work
established that topological insulator edges support a novel `magneto-Josephson
effect', whereby a dissipationless current exhibits 4\pi-periodic dependence
also on the relative orientation of the Zeeman fields in the two banks of the
junction. Here, we explore the magneto-Josephson effect in junctions based on
spin-orbit coupled quantum wires. In contrast to the topological insulator
case, the periodicities of the magneto-Josephson effect no longer follow from
an exact superconductor-magnetism duality of the Hamiltonian. We employ
numerical calculations as well as analytical arguments to identify the domain
configurations that display exotic Josephson physics for quantum-wire
junctions, and elucidate the characteristic differences with the corresponding
setups for topological insulators edges. To provide guidance to experiments, we
also estimate the magnitude of the magneto-Josephson effects in realistic
parameter regimes, and compare the Majorana-related contribution to the
coexisting 2\pi-periodic effects emerging from non-Majorana states.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con |
arxiv_dataset-42691304.7767 | Ubah?: Voting pattern in a sectarianized post-information-monopoly
population I. predictions from a simple projection model
physics.soc-ph
We predict the results of the upcoming elections in Malaysia using a
projective model for a sectarianized post-information-monopoly population.
| arxiv topic:physics.soc-ph |
arxiv_dataset-42701304.7867 | Spontaneous Clustering via Minimum \gamma-divergence
stat.ME
We propose a new method for clustering based on the local minimization of the
\gamma-divergence, which we call the spontaneous clustering. The greatest
advantage of the proposed method is that it automatically detects the number of
clusters that adequately reflect the data structure. In contrast, exiting
methods such as K-means, fuzzy c-means, and model based clustering need to
prescribe the number of clusters. We detect all the local minimum points of the
\gamma-divergence, which are defined as the centers of clusters. A necessary
and sufficient condition for the \gamma-divergence to have the local minimum
points is also derived in a simple setting. A simulation study and a real data
analysis are performed to compare our proposal with existing methods.
| arxiv topic:stat.ME |
arxiv_dataset-42711304.7967 | Noetherian quotients of the algebra of partial difference polynomials
and Grobner bases of symmetric ideals
math.AC math.AP
In this paper we develop a Grobner bases theory for ideals of partial
difference polynomials with constant or non-constant coefficients. In
particular, we introduce a criterion providing the finiteness of such bases
when a difference ideal contains elements with suitable linear leading
monomials. This can be explained in terms of Noetherianity of the corresponding
quotient algebra. Among these Noetherian quotients we find finitely generated
polynomial algebras where the action of suitable finite dimensional commutative
algebras and in particular finite abelian groups is defined. We obtain
therefore a consistent Grobner bases theory for ideals that possess such
symmetries.
| arxiv topic:math.AC math.AP |
arxiv_dataset-42721304.8067 | Semistar operations and standard closure operations
math.AC
Let $R$ be a commutative ring. It is shown that there is an order isomorphism
between a popular class of finite type closure operations on the ideals of $R$
and the poset of semistar operations of finite type.
| arxiv topic:math.AC |
arxiv_dataset-42731305.0032 | Construction of PMDS and SD Codes extending RAID 5
cs.IT math.IT
A construction of Partial Maximum Distance Separable (PMDS) and Sector-Disk
(SD) codes extending RAID 5 with two extra parities is given, solving an open
problem. Previous constructions relied on computer searches, while our
constructions provide a theoretical solution to the problem.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-42741305.0132 | Entangler via Electromagnetically Induced Transparency with Atomic
Ensembles
quant-ph
We present an efficient and convenient scheme to entangle multiple optical
fields via electromagnetically induced transparency in an atomic ensemble. The
atomic spin wave, produced through electromagnetically induced transparency in
the Lambda-type configuration in an atomic ensemble, can be described by a Bose
operator and acts as the entangler. By using the entangler, any desired number
of nondegenerate narrow-band continuous-variable entangled fields, in
principle, can be generated through stimulated Raman scattering processes,
which holds great promise for applications in scalable quantum communication
and quantum networks.
| arxiv topic:quant-ph |
arxiv_dataset-42751305.0232 | Radiation fields in star-forming galaxies: the disk, thin disk and bulge
astro-ph.CO
We provide and describe a library of diffuse stellar radiation fields in
spiral galaxies derived using calculations of the transfer of stellar radiation
from the main morphological components - disks, thin disks, and bulges -
through the dusty interstellar medium. These radiation fields are
self-consistent with the solutions for the integrated panchromatic spectral
energy distributions (SEDs) previously presented using the same model. Because
of this, observables calculated from the radiation fields, such as gamma-ray or
radio emission, can be self-consistently combined with the solutions for the
ultraviolet/optical/submillimeter SEDs, thus expanding the range of
applicability of the radiation transfer model to a broader range of wavelengths
and physical quantities. We also give analytic solutions for radiation fields
in optically thin stellar disks, in stellar disks with one dust disk and in
stellar disks with two dust disks. The analytic solutions for the direct light
are exact and can be used as benchmarks. The analytic solutions with scattering
are only approximate, becoming exact only in the extreme optically thick limit.
We find strongly contrasting solutions for the spatial distribution of the
radiation fields for disks, thin disks and bulges. For bulges we find a strong
dependence of the radiation fields on Sersic index.
| arxiv topic:astro-ph.CO |
arxiv_dataset-42761305.0332 | Volume term of work of critical nucleus formation in terms of chemical
potential difference relative to equilibrium one
physics.chem-ph cond-mat.stat-mech
The work of formation of a critical nucleus is sometimes written as
W=n{\Delta}{\mu}+{\gamma}A. The first term W_{vol}=n{\Delta}{\mu} is called the
volume term and the second term {\gamma}A the surface term with {\gamma} being
the interfacial tension and A the area of the nucleus. Nishioka and Kusaka [J.
Chem. Phys. 96 (1992) 5370] derived W_{vol}=n{\Delta}{\mu} with
n=V_{\beta}/v_{\beta} and
{\Delta}{\mu}={\mu}_{\beta}(T,p_{\alpha})-{\mu}_{\alpha}(T,p_{\alpha}) by
rewriting W_{vol}=-(p_{\beta}-p_{\alpha})V_{\beta} by integrating the
isothermal Gibbs-Duhem relation for an incompressible {\beta} phase, where
{\alpha} and {\beta} represent the parent and nucleating phases, V_{\beta} is
the volume of the nucleus, v_{\beta}, which is constant, the molecular volume
of the {\beta} phase, {\mu}, T, and p denote the chemical potential, the
temperature, and the pressure, respectively. We note here that
{\Delta}{\mu}={\mu}_{\beta}(T,p_{\alpha})-{\mu}_{\alpha}(T,p_{\alpha}) is, in
general, not a directly measurable quantity. In this paper, we have rewritten
W_{vol}=-(p_{\beta}-p_{\alpha})V_{\beta} in terms of {\mu}_{re}-{\mu}_{eq},
where {\mu}_{re} and {\mu}_{eq} are the chemical potential of the reservoir
(equaling that of the real system, common to the {\alpha} and {\beta} phases)
and that at equilibrium. Here, the quantity {\mu}_{re}-{\mu}_{eq} is the
directly measurable supersaturation. The obtained form is similar to but
slightly different from W_{vol}=n{\Delta}{\mu}.
| arxiv topic:physics.chem-ph cond-mat.stat-mech |
arxiv_dataset-42771305.0432 | Symmetries and gravitational Chern-Simons Lagrangian terms
hep-th gr-qc
We consider some general consequences of adding pure gravitational
Chern-Simons term to manifestly diff-covariant theories of gravity. Extending
the result of a previous paper we enlarge the class of metrics for which the
inclusion of a gCS term in the action does not affect solutions and
corresponding physical quantities. In the case in which such solutions describe
black holes (of general horizon topology) we show that the black hole entropy
is also unchanged. We arrive at these conclusions by proving three general
theorems and studying their consequences. One of the theorems states that the
contribution of the gravitational Chern-Simons to the black hole entropy is
invariant under local rescaling of the metric.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-42781305.0532 | Exponential asymptotics for line solitons in two-dimensional periodic
potentials
nlin.PS
As a first step toward a fully two-dimensional asymptotic theory for the
bifurcation of solitons from infinitesimal continuous waves, an analytical
theory is presented for line solitons, whose envelope varies only along one
direction, in general two-dimensional periodic potentials. For this
two-dimensional problem, it is no longer viable to rely on a certain recurrence
relation for going beyond all orders of the usual multi-scale perturbation
expansion, a key step of the exponential asymptotics procedure previously used
for solitons in one-dimensional problems. Instead, we propose a more direct
treatment which not only overcomes the recurrence-relation limitation, but also
simplifies the exponential asymptotics process. Using this modified technique,
we show that line solitons with any rational line slopes bifurcate out from
every Bloch-band edge; and for each rational slope, two line-soliton families
exist. Furthermore, line solitons can bifurcate from interior points of Bloch
bands as well, but such line solitons exist only for a couple of special line
angles due to resonance with the Bloch bands. In addition, we show that a
countable set of multi-line-soliton bound states can be constructed
analytically. The analytical predictions are compared with numerical results
for both symmetric and asymmetric potentials, and good agreement is obtained.
| arxiv topic:nlin.PS |
arxiv_dataset-42791305.0632 | The CP-matrix completion problem
math.OC
A symmetric matrix $C$ is completely positive (CP) if there exists an
entrywise nonnegative matrix $B$ such that $C=BB^T$. The CP-completion problem
is to study whether we can assign values to the missing entries of a partial
matrix (i.e., a matrix having unknown entries) such that the completed matrix
is completely positive. We propose a semidefinite algorithm for solving general
CP-completion problems, and study its properties. When all the diagonal entries
are given, the algorithm can give a certificate if a partial matrix is not
CP-completable, and it almost always gives a CP-completion if it is
CP-completable. When diagonal entries are partially given, similar properties
hold. Computational experiments are also presented to show how CP-completion
problems can be solved.
| arxiv topic:math.OC |
arxiv_dataset-42801305.0732 | Order of convexity of Integral Transforms and Duality
math.CV
Recently, Ali et al defined the class $\mathcal{W}_{\beta}(\alpha, \gamma)$
consisting of functions $f$ which satisfy $$\Re
e^{i\phi}\left((1-\alpha+2\gamma)\frac{f(z)}{z}+(\alpha-2\gamma)f'(z)+\gamma
zf''(z)-\beta\right)>0,$$ for all $z\in E=\left\{z : |z|<1\right\}$ and for
$\alpha, \gamma\geq0$ and $\beta<1$, $\phi\in \mathbb{R}$ (the set of reals).
For $f\in{\mathcal{W}_{\beta}(\alpha, \gamma)}$, they discussed the convexity
of the integral transform
$$V_{\lambda}(f)(z):=\int_{0}^{1}\lambda(t)\frac{f(tz)}{t}dt,$$ where $\lambda$
is a non-negative real-valued integrable function satisfying the condition
$\displaystyle\int_{0}^{1}\lambda(t)dt=1$. The aim of present paper is to find
conditions on $\lambda(t)$ such that $V_{\lambda}(f)$ is convex of order
$\delta$ ($0\leq\delta\leq1/2$) whenever $f\in{\mathcal{W}}_{\beta}(\alpha,
\gamma)$. As applications, we study various choices of $\lambda(t)$, related to
classical integral transforms.
| arxiv topic:math.CV |
arxiv_dataset-42811305.0832 | Implicit contractive maps in ordered metric spaces
math.GN
Further extensions are given to the fixed point result (for implicit
contractions) due to Altun and Simsek [Fixed Point Th. Appl., Volume 2010,
Article ID 621469]. Some connections with related statements in the area due to
Agarwal, El-Gebeily and O'Regan [Appl. Anal., 87 (2008), 109-116] are also
discussed. Finally, the old approach in Turinici [An. St. Univ. "A. I. Cuza"
Iasi, 22 (1976), 177-180] is presented, for historical reasons.
| arxiv topic:math.GN |
arxiv_dataset-42821305.0932 | Negative Conditional Entropy of Post-Selected States
quant-ph
We define a quantum entropy conditioned on post-selection which has the von
Neumann entropy of pure states as a special case. This conditional entropy can
take negative values which is consistent with part of a quantum system
containing less information than the whole which can be in a pure state. The
definition is based on generalised density operators for postselected
ensembles. The corresponding density operators are consistent with the quantum
generalisation of classical conditional probabilities following Dirac s
formalism of quasiprobability distributions.
| arxiv topic:quant-ph |
arxiv_dataset-42831305.1032 | Structural properties of dense hard spheres near random close packing
cond-mat.soft
We numerically study structural properties of mechanically stable packings of
hard spheres (HS), in a wide range of packing fractions $0.53 \le \phi \le
0.72$. Detailed structural information is obtained from the analysis of
orientational order parameters, which clearly reveals a disorder-order phase
transition at the random close packing (RCP) density, $\phi_{\rm c} \simeq
0.64$. Above $\phi_{\rm c}$ the crystalline nuclei form 3D-like clusters, which
upon further desification, transform into alternating planar-like layers. We
also find that particles with icosahedral symmetry survive only in a narrow
density range in the vicinity of the RCP transition.
| arxiv topic:cond-mat.soft |
arxiv_dataset-42841305.1132 | iota Horologi, the first coronal activity cycle in a young solar-like
star
astro-ph.SR astro-ph.EP
Context: The shortest chromospheric (Ca II H&K) activity cycle (1.6 yr) has
been recently discovered in the young (~600 Myr) solar-like star iota Hor.
Coronal X-ray activity cycles have only been discovered in a few stars other
than the Sun, all of them with an older age and a lower activity level than
iota Hor. Aims: We intended to find the X-ray coronal counterpart of the
chromospheric cycle for i Hor. This represents the first X-ray cycle observed
in an active star, as well as the paradigm of the first coronal cycles in the
life of a solar-like star. Methods: We monitored i Hor with XMM-Newton
observations spanning almost two years. The spectra of each observation are fit
with two-temperature coronal models to study the long-term variability of the
star. Results: We find a cyclic behavior in X-rays very similar to the
contemporaneous chromospheric cycle. The continuous chromospheric monitoring
for more than three cycle lengths shows a trend toward decreasing amplitude,
apparently modulated by a longer term trend. The second cycle is disrupted
prior to reaching its maximum, followed by a brief episode of chaotic
variability before the cyclic behavior resumes, only to be disrupted again
after slightly more than one cycle. Conclusions: We confirm the presence of an
activity cycle of ~1.6 yr in i Hor both in X-rays and Ca II H&K. It is likely
subject to the modulation of a longer, not yet constrained second cycle. The
1.6 yr cycle is the shortest coronal one observed to date, and i Hor represents
the most active star for which a coronal activity cycle has been found. This
cycle is probably representative of the first coronal cycles in the life of a
solar-like star, at the age when life started on Earth.
| arxiv topic:astro-ph.SR astro-ph.EP |
arxiv_dataset-42851305.1232 | Bayesian Modeling and MCMC Computation in Linear Logistic Regression for
Presence-only Data
stat.CO stat.OT
Presence-only data are referred to situations in which, given a censoring
mechanism, a binary response can be observed only with respect to on outcome,
usually called \textit{presence}. In this work we present a Bayesian approach
to the problem of presence-only data based on a two levels scheme. A
probability law and a case-control design are combined to handle the double
source of uncertainty: one due to the censoring and one due to the sampling. We
propose a new formalization for the logistic model with presence-only data that
allows further insight into inferential issues related to the model. We
concentrate on the case of the linear logistic regression and, in order to make
inference on the parameters of interest, we present a Markov Chain Monte Carlo
algorithm with data augmentation that does not require the a priori knowledge
of the population prevalence. A simulation study concerning 24,000 simulated
datasets related to different scenarios is presented comparing our proposal to
optimal benchmarks.
| arxiv topic:stat.CO stat.OT |
arxiv_dataset-42861305.1332 | Counting common perpendicular arcs in negative curvature
math.DG math.DS
Let $D^-$ and $D^+$ be properly immersed closed locally convex subsets of a
Riemannian manifold with pinched negative sectional curvature. Using mixing
properties of the geodesic flow, we give an asymptotic formula as $t\to+\infty$
for the number of common perpendiculars of length at most $t$ from $D^-$ to
$D^+$, counted with multiplicities, and we prove the equidistribution in the
outer and inner unit normal bundles of $D^-$ and $D^+$ of the tangent vectors
at the endpoints of the common perpendiculars. When the manifold is compact
with exponential decay of correlations or arithmetic with finite volume, we
give an error term for the asymptotic. As an application, we give an asymptotic
formula for the number of connected components of the domain of discontinuity
of Kleinian groups as their diameter goes to $0$.
| arxiv topic:math.DG math.DS |
arxiv_dataset-42871305.1432 | Pressure fluctuations in isotropic solids and fluids
cond-mat.soft
Comparing isotropic solids and fluids at either imposed volume or pressure we
investigate various correlations of the instantaneous pressure and its ideal
and excess contributions. Focusing on the compression modulus K it is
emphasized that the stress fluctuation representation of the elastic moduli may
be obtained directly (without a microscopic displacement field) by comparing
the stress fluctuations in conjugated ensembles. This is made manifest by
computing the Rowlinson stress fluctuation expression K_row of the compression
modulus for NPT-ensembles. It is shown theoretically and numerically that
K_row|P = P_id (2 - P_id/K) with P_id being the ideal pressure contribution.
| arxiv topic:cond-mat.soft |
arxiv_dataset-42881305.1532 | Relations between Projected Emittances and Eigenemittances
physics.acc-ph math-ph math.MP
We give necessary and sufficient conditions that two sets of positive real
numbers must satisfy in order to be realizable as eigenemittances and projected
emittances of a beam matrix. The information provided by these conditions sets
limits on what one can to achieve when designing a beam line to perform
advanced emittance manipulations.
| arxiv topic:physics.acc-ph math-ph math.MP |
arxiv_dataset-42891305.1632 | Non-perturbative Massive Solutions in Gravitational Higgs Mechanism
hep-th gr-qc
We construct exact non-perturbative massive solutions in the gravitational
Higgs mechanism. They confirm the conclusions of arXiv:1102.4991, which are
based on non-perturbative Hamiltonian analysis for the relevant metric degrees
of freedom, that while perturbatively unitarity may not be evident, no negative
norm state is present in the full nonlinear theory. The non-perturbative
massive solutions do not appear to exhibit instabilities and describe vacuum
configurations which are periodic in time, including purely longitudinal
solutions with isotropic periodically expanding and contracting spatial
dimensions, "cosmological strings" with only one periodically expanding and
contracting spatial dimension, and also purely non-longitudinal ("traceless")
periodically expanding and contracting solutions with constant spatial volume.
As an aside we also discuss massive solutions in New Massive Gravity. While
such solutions are present in the linearized theory, we argue that already at
the next-to-linear (quadratic) order in the equations of motion (and, more
generally, for weak-field configurations) there are no massive solutions.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-42901305.1732 | Tuning the electronic properties of J_eff=1/2 correlated semimetal in
epitaxial perovskite SrIrO3
cond-mat.str-el cond-mat.mtrl-sci
We investigated the electronic properties of epitaxially stabilized
perovskite SrIrO3 and demonstrated the effective strain-control on its
electronic structure. Comprehensive transport measurements showed that the
strong spin-orbit coupling renders a novel semimetallic phase for the J_eff=1/2
electrons rather than an ordinary correlated metal, elucidating the nontrivial
mechanism underlying the dimensionality-controlled metal-insulator transition
in iridates. The electron-hole symmetry of this correlated semimetal was found
to exhibit drastic variation when subject to bi-axial strain. Under compressive
strain, substantial electron-hole asymmetry is observed in contrast to the
tensile side, where the electron and hole effective masses are comparable,
illustrating the susceptivity of the J_eff=1/2 to structural distortion.
Tensile strain also shrinks the Fermi surface, indicative of an increasing
degree of correlation which is consistent with optical measurements. These
results pave a pathway to investigate and manipulate the electronic states in
spin-orbit-coupled correlated oxides, and lay the foundation for constructing
5d transition metal heterostructures.
| arxiv topic:cond-mat.str-el cond-mat.mtrl-sci |
arxiv_dataset-42911305.1832 | Probing atom-surface interactions by diffraction of Bose-Einstein
condensates
physics.atom-ph
In this article we analyze the Casimir-Polder interaction of atoms with a
solid grating and an additional repulsive interaction between the atoms and the
grating in the presence of an external laser source. The combined potential
landscape above the solid body is probed locally by diffraction of
Bose-Einstein condensates. Measured diffraction efficiencies reveal information
about the shape of the Casimir-Polder interaction and allow us to discern
between models based on a pairwise-summation (Hamaker) approach and Lifshitz
theory.
| arxiv topic:physics.atom-ph |
arxiv_dataset-42921305.1932 | Gravitational Waveforms for Precessing, Quasi-circular Binaries via
Multiple Scale Analysis and Uniform Asymptotics: The Near Spin Alignment Case
gr-qc astro-ph.CO
We calculate analytical gravitational waveforms in the time- and
frequency-domain for precessing quasi-circular binaries with spins of arbitrary
magnitude, but nearly aligned with the orbital angular momentum. We first
derive an analytical solution to the precession equations by expanding in the
misalignment angle and using multiple scale analysis to separate timescales. We
then use uniform asymptotic expansions to analytically Fourier transform the
time-domain waveform, thus extending the stationary-phase approximation, which
fails when precession is present. The resulting frequency-domain waveform
family has a high overlap with numerical waveforms obtained by direct
integration of the post-Newtonian equations of motion and discrete Fourier
transformations. Such a waveform family lays the foundations for the accurate
inclusion of spin precession effects in analytical gravitational waveforms, and
thus, it can aid in the detection and parameter estimation of gravitational
wave signals from the inspiral phase of precessing binary systems.
| arxiv topic:gr-qc astro-ph.CO |
arxiv_dataset-42931305.2032 | Condensation and jumping relay of droplets on lotus leaf
physics.flu-dyn cond-mat.soft
Dynamic behavior of micro water droplet condensed on a lotus leaf with
two-tier roughness is studied. Under laboratory environment, the contact angle
of the micro droplet on single micro papilla increases smoothly from 80 deg to
160 deg during the growth of condensed water. The best-known "self-clean"
phenomenon, will be lost. A striking observation is the out-of-plane jumping
relay of condensed droplets triggered by falling droplets, as well as its
sustained speed obtained in continuous jumping relays, enhance the automatic
removal of dropwise condensation without the help from any external force. The
surface tension energy dissipation is the main reason controlling the critical
size of jumping droplet and its onset velocity of rebounding.
| arxiv topic:physics.flu-dyn cond-mat.soft |
arxiv_dataset-42941305.2132 | Role of HIV RNA structure in recombination and speciation: romping in
purine A, keeps HTLV away
q-bio.GN
Extreme enrichment of the human immunodeficiency virus (HIV-1) RNA genome for
the purine A parallels the mild purine-loading of the RNAs of most organisms.
This should militate against loop-loop "kissing" interactions between the
structured viral genome and structured host RNAs, which can generate segments
of double-stranded RNA sufficient to trigger intracellular alarms. However,
human T cell leukaemia virus (HTLV-1), with the potential to invade the same
host cell, shows extreme enrichment for the pyrimidine C. Assuming the low GC%
HIV and the high GC% HTLV-1 to share a common ancestor, it was postulated that
differences in GC% arose to prevent homologous recombination between these
emerging lentiviral species. Sympatrically isolated by this intracellular
reproductive barrier, prototypic HIV-1 seized the AU-rich (low GC%) high ground
(thus committing to purine A rather than purine G). Prototypic HTLV-1 forwent
this advantage and evolved an independent evolutionary strategy. Evidence
supporting this hypothesis since its elaboration in the 1990s is growing. The
conflict between the needs to encode accurately both a protein, and nucleic
acid structure, is often resolved in favour of the nucleic acid because, apart
from regulatory roles, structure is critical for recombination. However, above
a sequence difference threshold, structure (and hence recombination) is
impaired. New species can then arise.
| arxiv topic:q-bio.GN |
arxiv_dataset-42951305.2232 | Two simple finite element methods for Reissner--Mindlin plates with
clamped boundary condition
math.NA
We present two simple finite element methods for the discretization of
Reissner--Mindlin plate equations with {\em clamped} boundary condition. These
finite element methods are based on discrete Lagrange multiplier spaces from
mortar finite element techniques. We prove optimal a priori error estimates for
both methods.
| arxiv topic:math.NA |
arxiv_dataset-42961305.2332 | On 1/f^alpha power laws originating from linear neuronal cable theory:
power spectral densities of the soma potential, transmembrane current and
single-neuron contribution to the EEG
physics.bio-ph q-bio.NC
Power laws, that is, power spectral densities (PSDs) exhibiting 1/f^alpha
behavior for large frequencies f, have commonly been observed in neural
recordings. Power laws in noise spectra have not only been observed in
microscopic recordings of neural membrane potentials and membrane currents, but
also in macroscopic EEG (electroencephalographic) recordings. While complex
network behavior has been suggested to be at the root of this phenomenon, we
here demonstrate a possible origin of such power laws in the biophysical
properties of single neurons described by the standard cable equation. Taking
advantage of the analytical tractability of the so called ball and stick neuron
model, we derive general expressions for the PSD transfer functions for a set
of measures of neuronal activity: the soma membrane current, the current-dipole
moment (corresponding to the single-neuron EEG contribution), and the soma
membrane potential. These PSD transfer functions relate the PSDs of the
respective measurements to the PSDs of the noisy input currents. With
homogeneously distributed input currents across the neuronal membrane we find
that all PSD transfer functions express asymptotic high-frequency 1/f^alpha
power laws. The corresponding power-law exponents are analytically identified
as alpha_inf^I = 1/2 for the soma membrane current, alpha_inf^p = 3/2 for the
current-dipole moment, and alpha_inf^V = 2 for the soma membrane potential.
These power-law exponents are found for arbitrary combinations of uncorrelated
and correlated noisy input current (as long as both the dendrites and the soma
receive some uncorrelated input currents). Comparison with available data
suggests that the apparent power laws observed in experiments may stem from
uncorrelated current sources, presumably intrinsic ion channels, which are
homogeneously distributed across the neural membranes and themselves exhibit
...
| arxiv topic:physics.bio-ph q-bio.NC |
arxiv_dataset-42971305.2432 | Small Support Equilibria in Large Games
cs.GT
In this note we provide a new proof for the results of Lipton et al. on the
existence of an approximate Nash equilibrium with logarithmic support size.
Besides its simplicity, the new proof leads to the following contributions:
1. For n-player games, we improve the bound on the size of the support of an
approximate Nash equilibrium.
2. We generalize the result of Daskalakis and Papadimitriou on small
probability games from the two-player case to the general n-player case.
3. We provide a logarithmic bound on the size of the support of an
approximate Nash equilibrium in the case of graphical games.
| arxiv topic:cs.GT |
arxiv_dataset-42981305.2532 | Learning Policies for Contextual Submodular Prediction
cs.LG stat.ML
Many prediction domains, such as ad placement, recommendation, trajectory
prediction, and document summarization, require predicting a set or list of
options. Such lists are often evaluated using submodular reward functions that
measure both quality and diversity. We propose a simple, efficient, and
provably near-optimal approach to optimizing such prediction problems based on
no-regret learning. Our method leverages a surprising result from online
submodular optimization: a single no-regret online learner can compete with an
optimal sequence of predictions. Compared to previous work, which either learn
a sequence of classifiers or rely on stronger assumptions such as
realizability, we ensure both data-efficiency as well as performance guarantees
in the fully agnostic setting. Experiments validate the efficiency and
applicability of the approach on a wide range of problems including manipulator
trajectory optimization, news recommendation and document summarization.
| arxiv topic:cs.LG stat.ML |
arxiv_dataset-42991305.2632 | Multiple lattice tiles and Riesz bases of exponentials
math.CA
Suppose $\Omega\subseteq\RR^d$ is a bounded and measurable set and $\Lambda
\subseteq \RR^d$ is a lattice. Suppose also that $\Omega$ tiles multiply, at
level $k$, when translated at the locations $\Lambda$. This means that the
$\Lambda$-translates of $\Omega$ cover almost every point of $\RR^d$ exactly
$k$ times. We show here that there is a set of exponentials $\exp(2\pi i t\cdot
x)$, $t\in T$, where $T$ is some countable subset of $\RR^d$, which forms a
Riesz basis of $L^2(\Omega)$. This result was recently proved by Grepstad and
Lev under the extra assumption that $\Omega$ has boundary of measure 0, using
methods from the theory of quasicrystals. Our approach is rather more
elementary and is based almost entirely on linear algebra. The set of
frequencies $T$ turns out to be a finite union of shifted copies of the dual
lattice $\Lambda^*$. It can be chosen knowing only $\Lambda$ and $k$ and is the
same for all $\Omega$ that tile multiply with $\Lambda$.
| arxiv topic:math.CA |
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