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arxiv_dataset-56001409.7575 | Effect of LOS/NLOS Propagation on Area Spectral Efficiency and Energy
Efficiency of Small-Cells
cs.NI
In this paper we investigate the effect of Line-of-Sight (LOS) and
Non-Line-of-Sight (NLOS) propagation on the Area Spectral Efficiency (ASE) and
on the energy efficiency of dense small-cell networks. We show that including
both LOS and NLOS propagation in the path-loss model provides a completely
different picture of the behaviours of ASE and energy efficiency than what
would be observed in case of either LOS or NLOS propagation only. In
particular, with combined LOS/NLOS path-loss, the ASE exhibits superlinear and
sublinear behaviour at low and high cell densities, respectively. In addition,
the energy efficiency as a function of the cell density has a global maximum
and is not a monotonically increasing function like in case of LOS or NLOS
propagation only. Based on our findings, we claim that Line-of-Sight (LOS) and
Non-Line-of-Sight (NLOS) propagations play an important role in studying the
performance of extremely dense small-cell networks.
| arxiv topic:cs.NI |
arxiv_dataset-56011409.7675 | A derivation of the optimal answer-copying index and some applications
math.ST stat.AP stat.TH
Multiple-choice exams are frequently used as an efficient and objective
method to assess learning but they are more vulnerable to answer-copying than
tests based on open questions. Several statistical tests (known as indices in
the literature) have been proposed to detect cheating; however, to the best of
our knowledge they all lack mathematical support that guarantees optimality in
any sense. We partially fill this void by deriving the uniform most powerful
(UMP) under the assumption that the response distribution is known. In
practice, however, we must estimate a behavioral model that yields a response
distribution for each question. We calculate the empirical type-I and type-II
error rates for several indices that assume different behavioral models using
simulations based on real data from twelve nationwide multiple-choice exams
taken by 5th and 9th graders in Colombia. We find that the index with the
highest power among those studied, subject to the restriction of preserving the
type-I error, is one based on the work of Wollack (1997) and Linden and
Sotaridona (2006) and is superior to the indices studied and developed by
Wesolowsky (2000) and Frary, Tideman, and Watts (1977). We compare the results
of applying this index to all 12 exams and find that examination rooms with
stricter proctoring have a lower level of copying. Finally, a Bonferroni
correction to control for the false positive rate is proposed to detect massive
cheating.
| arxiv topic:math.ST stat.AP stat.TH |
arxiv_dataset-56021409.7775 | Quantum optics: Push-button photon entanglement
physics.pop-ph quant-ph
A source of entangled photons that emits one, and only one, pair of photons
on demand has now been realized in a semiconductor chip. The solid-state source
will be a useful resource for experiments in optical quantum information.
| arxiv topic:physics.pop-ph quant-ph |
arxiv_dataset-56031409.7875 | Randomness Requirement on CHSH Bell Test in the Multiple Run Scenario
quant-ph
The Clauser-Horne-Shimony-Holt inequality test is widely used as a mean of
invalidating the local deterministic theories and a tool of device independent
quantum cryptographic tasks. There exists a randomness (freewill) loophole in
the test, which is widely believed impossible to be closed perfectly. That is,
certain random inputs are required for the test. Following a randomness
quantification method used in literature, we investigate the randomness
required in the test under various assumptions. By comparing the results, one
can conclude that the key to make the test result reliable is to rule out
correlations between multiple runs.
| arxiv topic:quant-ph |
arxiv_dataset-56041409.7975 | The smallest singular value of random rectangular matrices with no
moment assumptions on entries
math.PR
Let $\delta>1$ and $\beta>0$ be some real numbers. We prove that there are
positive $u,v,N_0$ depending only on $\beta$ and $\delta$ with the following
property: for any $N,n$ such that $N\ge \max(N_0,\delta n)$, any $N\times n$
random matrix $A=(a_{ij})$ with i.i.d. entries satisfying
$\sup\limits_{\lambda\in {\mathbb R}}{\mathbb P}\bigl\{|a_{11}-\lambda|\le
1\bigr\}\le 1-\beta$ and any non-random $N\times n$ matrix $B$, the smallest
singular value $s_n$ of $A+B$ satisfies ${\mathbb P}\bigl\{s_n(A+B)\le
u\sqrt{N}\bigr\}\le \exp(-vN)$. The result holds without any moment assumptions
on distribution of the entries of $A$.
| arxiv topic:math.PR |
arxiv_dataset-56051409.8075 | Mechanism of r-mode stability in young rapidly rotating pulsars
astro-ph.HE astro-ph.SR nucl-th
We demonstrate that stability of r-modes in young rapidly rotating pulsars
might be explained if one takes into account strong medium modifications of the
nucleon-nucleon interaction because of the softening of pionic degrees of
freedom in dense nucleon matter. Presence of the efficient direct Urca
processes is not required. Within our model the most rapidly rotating observed
young pulsar PSR J0537-6910 should have the mass $\geq 1.8M_{\odot}$.
| arxiv topic:astro-ph.HE astro-ph.SR nucl-th |
arxiv_dataset-56061409.8175 | Kinetic Model of Mass Exchange with Dynamic Arrhenius Transition Rates
cond-mat.stat-mech cond-mat.mtrl-sci
We study a nonlinear kinetic model of mass exchange between interacting
grains. The transition rates follow the Arrhenius equation with an activation
energy that depends on the grain mass. We show that the activation parameter
can be absorbed in the initial conditions for the grain masses, and that the
total mass is conserved. We obtain numerical solutions of the coupled,
nonlinear, ordinary differential equations of mass exchange for the two-grain
system, and we compare them with approximate theoretical solutions in specific
neighborhoods of the phase space. Using phase plane methods, we determine that
the system exhibits regimes of diffusive and growth-decay (reverse diffusion)
kinetics. The equilibrium states are determined by the mass equipartition and
separation nullcline curves. If the transfer rates are perturbed by white
noise, numerical simulations show that the system still exhibits diffusive and
growth-decay regimes, although the noise can reverse the sign of equilibrium
mass difference. Finally, we present theoretical analysis and numerical
simulations of a system with many interacting grains. Diffusive and
growth-decay regimes are established as well, but the approach to equilibrium
is considerably slower. Potential applications of the mass exchange model
involve coarse-graining during sintering and wealth exchange in econophysics.
| arxiv topic:cond-mat.stat-mech cond-mat.mtrl-sci |
arxiv_dataset-56071409.8275 | Elastic Nanocomputation in an Ideal Brain (1p abstract + 36 pages + 49
endnotes)
q-bio.NC
This explanation of what a brain is and does rests on informational first
principles, because information theory, like its parent theory thermodynamics,
is mathematically sacrosanct, itself resting on real-valued probability.Just as
thermodynamics has enabled hyper-potent physical technologies from the internal
combustion engine to the hydrogen bomb, so information theory has enabled
hyper-persuasive technologies, from color television to addictive video games.
Only a theory of what a brain is and does based on those same principles makes
legible and transparent the mechanisms by which such hyper-persuasion works. In
information-theoretic terms, a brain is a specialized real-valued real-time 3D
processor detecting discontinuities in spacetime outside itself and
reconstituting in itself a continuous reality based on them. This continuous
approach is difficult to reconcile with any computational architecture based on
separate neurons, and in fact the vast discrepancy in efficiency (of order at
least a hundred million) between those architectures constitutes the
calculations of this paper. This remarkable signal-processing requires strong
prior hypotheses embedded in 3D edge-detecting algorithms, priors which
unfortunately also open an unpatchable security hole to automated persuasion.
So a 3D model of the brain is essential for understanding how and why
persuasive technologies alter our perception of reality, and for protecting us
against systemic, systematic cognitive manipulation.
| arxiv topic:q-bio.NC |
arxiv_dataset-56081409.8375 | Parameterization of Deformed Nuclei for Glauber Modeling in Relativistic
Heavy Ion Collisions
nucl-th hep-ph
The density distributions of large nuclei are typically modeled with a
Woods-Saxon distribution characterized by a radius $R_{0}$ and skin depth $a$.
Deformation parameters $\beta$ are then introduced to describe non-spherical
nuclei using an expansion in spherical harmonics
$R_{0}(1+\beta_2Y^0_2+\beta_4Y^0_4)$. But when a nucleus is non-spherical, the
$R_{0}$ and $a$ inferred from electron scattering experiments that integrate
over all nuclear orientations cannot be used directly as the parameters in the
Woods-Saxon distribution. In addition, the $\beta_2$ values typically derived
from the reduced electric quadrupole transition probability B(E2)$\uparrow$ are
not directly related to the $\beta_2$ values used in the spherical harmonic
expansion. B(E2)$\uparrow$ is more accurately related to the intrinsic
quadrupole moment $Q_{0}$ than to $\beta_2$. One can however calculate $Q_0$
for a given $\beta_2$ and then derive B(E2)$\uparrow$ from $Q_0$. In this paper
we calculate and tabulate the $R_0$, $a$, and $\beta_2$ values that when used
in a Woods-Saxon distribution, will give results consistent with electron
scattering data. We then present calculations of the eccentricity
$\varepsilon_2$ and $\varepsilon_3$ with the new and old parameters. We
demonstrate that $\varepsilon_3$ is particularly sensitive to $a$ and argue
that using the incorrect value of $a$ has important implications for the
extraction of $\eta/s$ from the QGP created in Heavy Ion collisions.
| arxiv topic:nucl-th hep-ph |
arxiv_dataset-56091409.8475 | On the temporal decay of solutions to the two-dimensional nematic liquid
crystal flows
math.AP
We consider the temporal decay estimates for weak solutions to the
two-dimensional nematic liquid crystal flows, and we show that the energy norm
of a global weak solution has non-uniform decay \begin{align*}
\|u(t)\|_{L^{2}}+\|\nabla d(t)\|_{L^{2}}\rightarrow 0\quad \text{ as }
t\rightarrow \infty, \end{align*} under suitable conditions on the initial
data. We also show the exact rate of the decay (uniform decay) of the energy
norm of the global weak solution.
| arxiv topic:math.AP |
arxiv_dataset-56101409.8575 | Absence of Red Structural Color in Photonic Glasses, Bird Feathers and
Certain Beetles
cond-mat.soft physics.optics
Colloidal glasses, bird feathers, and beetle scales can all show structural
colors arising from short-ranged spatial correlations between scattering
centers. Unlike the structural colors arising from Bragg diffraction in ordered
materials like opals, the colors of these photonic glasses are independent of
orientation, owing to their disordered, isotropic microstructures. However,
there are few examples of photonic glasses with angle-independent red colors in
nature, and colloidal glasses with particle sizes chosen to yield structural
colors in the red show weak color saturation. Using scattering theory, we show
that the absence of angle-independent red color can be explained by the
tendency of individual particles to backscatter light more strongly in the
blue. We discuss how the backscattering resonances of individual particles
arise from cavity-like modes, and how they interact with the structural
resonances to prevent red. Finally, we use the model to develop design rules
for colloidal glasses with red, angle-independent structural colors.
| arxiv topic:cond-mat.soft physics.optics |
arxiv_dataset-56111409.8675 | Disordered and interacting parabolic semimetals in two and three
dimensions
cond-mat.str-el cond-mat.dis-nn
A clean noninteracting parabolic semimetal is characterized by quadratic band
touching between the conduction and the valence bands at isolated diabolic
points in the Brillouin zone and describes a fermionic quantum critical system
with dynamic exponent z=2. We consider the stability of such a semimetal
against electronic interaction and quenched disorder using a perturbative
renormalization group analysis for two and three spatial dimensions. For the
noninteracting problem infinitesimally weak disorder leads to an Anderson
insulator and a diffusive metal respectively in two and three dimensions. On
the other hand, the long range Coulomb interaction causes an excitonic
instability for the clean interacting problem towards a broken symmetry ground
state in both dimensions. Our weak coupling analysis of the combined effects of
disorder and interaction suggests the competition between a broken symmetry and
a disorder controlled metallic or insulating states, but is inadequate for
describing the quantum phase transitions among them. We discuss the relevance
of our results for bilayer graphene and some 227 iridate compounds, and
identify these materials as promising candidates for exploring novel disorder
and interaction controlled quantum critical phenomena.
| arxiv topic:cond-mat.str-el cond-mat.dis-nn |
arxiv_dataset-56121410.0099 | Coalescence and meeting times on $n$-block Markov chains
math.PR math.DS
We consider finite state, discrete-time, mixing Markov chains $(V,P)$, where
$V$ is the state space and $P$ is transition matrix. To each such chain
$(V,P)$, we associate a sequence of chains $(V_n,P_n)$ by coding trajectories
of $(V,P)$ according to their overlapping $n$-blocks. The chain $(V_n,P_n)$,
called the $n$-block Markov chain associated to $(V,P)$, may be considered an
alternate version of $(V,P)$ having memory of length $n$. Along such a sequence
of chains, we characterize the asymptotic behavior of coalescence times and
meeting times as $n$ tends to infinity. In particular, we define an algebraic
quantity $L(V,P)$ depending only on $(V,P)$, and we show that if the
coalescence time on $(V_n,P_n)$ is denoted by $C_n$, then the quantity
$\frac{1}{n} \log C_n$ converges in probability to $L(V,P)$ with exponential
rate. Furthermore, we fully characterize the relationship between $L(V,P)$ and
the entropy of $(V,P)$.
| arxiv topic:math.PR math.DS |
arxiv_dataset-56131410.0199 | Isotropic star in low-mass X-ray binaries and X-ray pulsars
gr-qc
We present a model for compact stars in the low mass X-ray binaries(LMXBs)
and X-ray pulsars using a metric given by John J. Matese and Patrick G. Whitman
\citep{Matese and Whitman1980}. Here the field equations are reduced to a
system of two algebraic equations considering the isotropic pressure. Compact
star candidates 4U 1820-30(radius=10km) in LMXBs, and Her X-1(radius=7.7km),
SAX J 1808.4-3658(SS1)(radius=7.07km) and SAX J 1808.4-3658(SS2)(radius=6.35km)
in X-ray pulsars satisfy all the energy conditions, TOV-equation and stability
condition. From our model, we have derived mass($M$), central
density($\rho_{0}$), suface density($\rho_{b}$), central pressure($p_{0}$),
surface pressure($p_{b}$) and surface red-shift($Z_{s}$) of the above mentioned
stars, which are very much consistant with the observed/reported datas\citep{N.
K. Glendenning1997,Gondek2000}. We have also observe the adiabatic
index($\gamma$>4/3) of the above steller objects.
| arxiv topic:gr-qc |
arxiv_dataset-56141410.0299 | Asymptotic Expansions for High-Contrast Linear Elasticity
math.NA math.AP
We study linear elasticity problems with high contrast in the coefficients
using asymptotic limits recently introduced. We derive an asymptotic expansion
to solve heterogeneous elasticity problems in terms of the contrast in the
coefficients. We study the convergence of the expansion in the $H^1$ norm.
| arxiv topic:math.NA math.AP |
arxiv_dataset-56151410.0399 | 2D Schr\"odinger Equation with Mixed Potential in Noncommutaive Complex
space
quant-ph
We obtain exact solutions of the 2D Schr\"odinger equation for Hydrogen atom
with the lenear and Harmonic Potentials in noncommutative complex space, using
the Power-series expansion method. Hence we can say that the Schr\"odinger
equation in noncommutative complex space describes to the particles with spin
(1/2)in an external uniform magnitic field. Where the noncommutativity play the
role of magnetic field with created the total magnetic moment of particle with
spin 1/2, who in turn shifted the spectrum of energy. Such effects are similar
to the Zeeman splitting in a commutative space.
| arxiv topic:quant-ph |
arxiv_dataset-56161410.0499 | Reflecting random flights
math.PR
We consider random flights in $\mathbb{R}^d$ reflecting on the surface of a
sphere $\mathbb{S}^{d-1}_R,$ with center at the origin and with radius $R,$
where reflection is performed by means of circular inversion. Random flights
studied in this paper are motions where the orientation of the deviations are
uniformly distributed on the unit-radius sphere $\mathbb{S}^{d-1}_1$.
We obtain the explicit probability distributions of the position of the
moving particle when the number of changes of direction is fixed and equal to
$n\geq 1$. We show that these distributions involve functions which are
solutions of the Euler-Darboux-Poisson equation. The unconditional probability
distributions of the reflecting random flights are obtained by suitably
randomizing $n$ by means of a fractional-type Poisson process.
Random flights reflecting on hyperplanes according to the optical reflection
form are considered and the related distributional properties derived.
| arxiv topic:math.PR |
arxiv_dataset-56171410.0599 | Geomagnetic field intensity in the middle jurassic - oligocene
physics.geo-ph
The present paper summarizes results of the studies on the intensity of
geomagnetic field in the (167 - 23) Ma interval by sedimentary rocks of the
Russian Plate and adjacent territories. The joint analysis of the data
paleointensity obtained by sedimentary and thermomagnetized (from PINT12) rocks
within this temporal interval is conducted. It is shown that the changes of the
paleointensity were occurred chaotically. Alternating bursts and periods of
quiet regime of the geomagnetic field are typical for intermittent processes
and is a characteristic of the geological interval Jurassic-beginning of
Paleogene. The distributions of the paleointensity corresponding to different
intervals of geologic time were investigated. It is revealed that the
cumulative distribution function (CDF) of the paleointensity values is best
approximated by a power function. The indices of the power functions varied
depending on geologic time intervals.The analysis of the paleomagnetic data
suggests that the medium in which the geomagnetic field is generated is
turbulent. Turbulence in the Earth's liquid core is enhanced in the Cretaceous
compared with Jurassic and Paleogene.
| arxiv topic:physics.geo-ph |
arxiv_dataset-56181410.0699 | An abstract continuity theorem of the Lyapunov exponents
math.DS math-ph math.FA math.MP math.PR
We devise an abstract, modular scheme to prove continuity of the Lyapunov
exponents for a general class of linear cocycles. The main assumption is the
availability of appropriate large deviation type (LDT) estimates which are
uniform in the data. We provide a modulus of continuity that depends explicitly
on the sharpness of the LDT estimate. Our method uses an inductive procedure
based on the deterministic, general Avalanche Principle in [4]. The main
advantage of this approach, besides the fact that it provides quantitative
estimates, is its versatility, as it applies to quasi-periodic cocycles (one
and multivariable torus translations), to random cocycles (i.i.d. and Markov
systems) and to any other types of base dynamics as long as appropriate LDT
estimates are satisfied. Moreover, compared to other available quantitative
results for quasi-periodic or random cocycles, this method allows for weaker
assumptions.
This is a draft of a chapter in our forthcoming research monograph [4].
| arxiv topic:math.DS math-ph math.FA math.MP math.PR |
arxiv_dataset-56191410.0799 | Optimization of radiation hardness and charge collection of edgeless
silicon pixel sensors for photon science
physics.ins-det
Recent progress in active-edge technology of silicon sensors enables the
development of large-area tiled silicon pixel detectors with small dead space
between modules by utilizing edgeless sensors. Such technology has been proven
in successful productions of ATLAS and Medipix-based silicon pixel sensors by a
few foundries. However, the drawbacks of edgeless sensors are poor radiation
hardness for ionizing radiation and non-uniform charge collection by edge
pixels. In this work, the radiation hardness of edgeless sensors with different
polarities has been investigated using Synopsys TCAD with X-ray
radiation-damage parameters implemented. Results show that if no conventional
guard ring is present, none of the current designs are able to achieve a high
breakdown voltage (typically < 30 V) after irradiation to a dose of ~10 MGy. In
addition, a charge-collection model has been developed and was used to
calculate the charges collected by the edge pixels of edgeless sensors when
illuminated with X-rays. The model takes into account the electric field
distribution inside the pixel sensor, the absorption of X-rays, drift and
diffusion of electrons and holes, charge sharing effect, and threshold settings
in ASICs. It is found that the non-uniform charge collection of edge pixels is
caused by the strong bending of electric field and the non-uniformity depends
on bias voltage, sensor thickness and distance from active edge to the last
pixel ("edge space"). In particular, the last few pixels close to the active
edge of the sensor are not sensitive to low-energy X-rays (< 10 keV) especially
for sensors with thicker Si and smaller edge space. The results from the model
calculation have been compared to measurements and good agreement was obtained.
The model has been used to optimize the edge design.
| arxiv topic:physics.ins-det |
arxiv_dataset-56201410.0899 | The holographic supersymmetric Renyi entropy in five dimensions
hep-th
We compute the supersymmetric Renyi entropy across an entangling three-sphere
for five-dimensional superconformal field theories using localization. For a
class of USp(2N) gauge theories we construct a holographic dual 1/2 BPS black
hole solution of Euclidean Romans F(4) supergravity. The large N limit of the
gauge theory results agree perfectly with the supergravity computations.
| arxiv topic:hep-th |
arxiv_dataset-56211410.0999 | Quantum criticality of the sub-Ohmic spin-boson model within displaced
Fock states
quant-ph
The spin-boson model is analytically studied using displaced Fock states
(DFS) without discretization of the continuum bath. In the orthogonal displaced
Fock basis, the ground-state wavefunction can be systematically improved in a
controllable way. Interestingly, the zeroth-order DFS reproduces exactly the
well known Silbey-Harris results. In the framework of the second-order DFS, the
magnetization and the entanglement entropy are exactly calculated. It is found
that the magnetic critical exponent $\beta$ is converged to $0.5$ in the whole
sub-Ohmic bath regime $0<s<1$, compared with that by the exactly solvable
generalized Silbey-Harris ansatz. It is strongly suggested that the system with
sub-Ohmic bath is always above its upper critical dimension, in sharp contrast
with the previous findings. This is the first evidence of the violation of the
quantum-classical Mapping for $% 1/2<s<1$.
| arxiv topic:quant-ph |
arxiv_dataset-56221410.1099 | Linear-optical generation of eigenstates of the two-site XY model
quant-ph
Much of the anticipation accompanying the development of a quantum computer
relates to its application to simulating dynamics of another quantum system of
interest. Here we study the building blocks for simulating quantum spin systems
with linear optics. We experimentally generate the eigenstates of the XY
Hamiltonian under an external magnetic field. The implemented quantum circuit
consists of two CNOT gates, which are realized experimentally by harnessing
entanglement from a photon source and by applying a CPhase gate. We tune the
ratio of coupling constants and magnetic field by changing local parameters.
This implementation of the XY model using linear quantum optics might open the
door to the future studies of quenching dynamics using linear optics.
| arxiv topic:quant-ph |
arxiv_dataset-56231410.1199 | Could the Vegard strains govern extrinsic size effects in nanoparticles?
cond-mat.mtrl-sci cond-mat.mes-hall
In the paper we propose a theoretical model that takes into account Vegard
strains and perform a detailed quantitative comparison of the theoretical
results with experimental ones for quasispherical nanoparticles, which reveal
the essential (about 100 K) increase of the transition temperature in spherical
nanoparticles in comparison with bulk crystals. The average radius of
nanoparticles was about 25 nm, they consist of K(Ta,Nb)O3 solid solution, where
KTaO3 is a quantum paraelectric, while KNbO3 is a ferroelectric.From the
comparison between the theory and experiment we unambiguously established the
leading contribution of Vegard strains into the extrinsic size effect in
ferroelectric nanoparticles. We determined the dependence of Vegard strains on
the content of Nb and reconstructed the Curie temperature dependence on the
content of Nb using this dependence. Appeared that the dependence of the Curie
temperature on the Nb content becomes nonmonotonic one for the small (< 20 nm)
elongated K(Ta,Nb)O3 nanoparticles. We established that the accumulation of
intrinsic and extrinsic defects near the surface can play the key role in the
physical origin of extrinsic size effect in ferroelecric nanoparticles and
govern its main features.
| arxiv topic:cond-mat.mtrl-sci cond-mat.mes-hall |
arxiv_dataset-56241410.1299 | Double-Fock Superposition Interferometry for Differential Diagnosis of
Decoherence
quant-ph
Interferometric signals are degraded by decoherence, which encompasses
dephasing, mixing and any distinguishing which-path information. These three
paradigmatic processes are fundamentally different, but, for coherent,
single-photon and $N00N$-states, they degrade interferometric visibility in the
very same way, which impedes the diagnosis of the cause for reduced visibility
in a single experiment. We introduce a versatile formalism for many-boson
interferometry based on double-sided Feynman diagrams, which we apply to a
protocol for differential decoherence diagnosis: Twin-Fock states |N,N> with $N
\ge 2$ reveal to which extent decoherence is due to path distinguishability or
to mixing, while double-Fock superpositions $|N:M> = (|N,M> + |M,N>)/\sqrt{2} $
with $N > M >0$ additionally witness the degree of dephasing. Hence,
double-Fock superposition interferometry permits the differential diagnosis of
decoherence processes in a single experiment, indispensable for the assessment
of interferometers.
| arxiv topic:quant-ph |
arxiv_dataset-56251410.1399 | Test Beam Campaigns for the CMS Phase I Upgrade Pixel Readout Chip
physics.ins-det hep-ex
The current CMS silicon pixel detector as the innermost component of the CMS
experiment is performing well at LHC design luminosity, but would be subject to
severe inefficiencies at LHC peak luminosities of 2x10e34 cm^-2 s^-1.
Therefore, an upgrade of the CMS pixel detector is planned, including a new
readout chip. The chip design comprises additional on-chip buffer cells as well
as high-speed data links and low-threshold comparators in the pixel cells. With
these changes the upgraded pixel detector will be able to maintain or even
improve the efficiency of the current detector at the increased requirements
imposed by high luminosities and pile-up.
The effects of these design changes on e.g. position resolution and charge
collection efficiency were studied in detail using a precision tracking
telescope at the DESY test beam facilities. The high telescope track resolution
enables precise studies of tracking efficiency, charge sharing and collection
even within single pixel cells of the device under test.
This publication focuses on the improved performance and capabilities of the
new pixel readout chip and summarizes results from test beam campaigns with
both unirradiated and irradiated devices. The functionality of the chip design
with its improved charge threshold, redesigned data transmission and buffering
scheme has been verified.
| arxiv topic:physics.ins-det hep-ex |
arxiv_dataset-56261410.1499 | Exact solution of a (2 + 1) dimensional anisotropic star in Finch and
Skea spacetime
physics.gen-ph
We provide a new class of interior solution of a (2 + 1) dimensional
anisotropic star in Finch and Skea spacetime corresponding to the BTZ black
hole. We have developed the model by considering the MIT bag model EOS and a
particular ansatz for the metric function $ g_{rr}$ proposed by Finch and Skea
\cite{FS}. Our model is free from central singularity and satisfied all the
physical requirements for the acceptability of the model.
| arxiv topic:physics.gen-ph |
arxiv_dataset-56271410.1599 | Accelerated Multiple Precision Matrix Multiplication using Strassen's
Algorithm and Winograd's Variant
math.NA cs.NA
The Strassen algorithm and Winograd's variant accelerate matrix
multiplication by using fewer arithmetic operations than standard matrix
multiplication. Although many papers have been published to accelerate single-
as well as double-precision matrix multiplication by using these algorithms, no
research to date has been undertaken to accelerate multiple precision matrix
multiplication. In this paper, we propose a multiple precision matrix
multiplication program for matrices of any size and test its performance. We
also reveal special properties of our program through its application to LU
decomposition.
| arxiv topic:math.NA cs.NA |
arxiv_dataset-56281410.1699 | Mumford-Shah and Potts Regularization for Manifold-Valued Data with
Applications to DTI and Q-Ball Imaging
math.NA cs.CV math.OC physics.med-ph
Mumford-Shah and Potts functionals are powerful variational models for
regularization which are widely used in signal and image processing; typical
applications are edge-preserving denoising and segmentation. Being both
non-smooth and non-convex, they are computationally challenging even for scalar
data. For manifold-valued data, the problem becomes even more involved since
typical features of vector spaces are not available. In this paper, we propose
algorithms for Mumford-Shah and for Potts regularization of manifold-valued
signals and images. For the univariate problems, we derive solvers based on
dynamic programming combined with (convex) optimization techniques for
manifold-valued data. For the class of Cartan-Hadamard manifolds (which
includes the data space in diffusion tensor imaging), we show that our
algorithms compute global minimizers for any starting point. For the
multivariate Mumford-Shah and Potts problems (for image regularization) we
propose a splitting into suitable subproblems which we can solve exactly using
the techniques developed for the corresponding univariate problems. Our method
does not require any a priori restrictions on the edge set and we do not have
to discretize the data space. We apply our method to diffusion tensor imaging
(DTI) as well as Q-ball imaging. Using the DTI model, we obtain a segmentation
of the corpus callosum.
| arxiv topic:math.NA cs.CV math.OC physics.med-ph |
arxiv_dataset-56291410.1799 | Including birefringence into time evolution of CMB: current and future
constraints
astro-ph.CO
We introduce birefringence effects within the propagation history of CMB,
considering the two cases of a constant effect and of an effect that increases
linearly in time, as the rotation of polarization induced by birefringence
accumulates during photon propagation. Both cases result into a mixing of E and
B modes before lensing effects take place, thus leading to the fact that
lensing is acting on spectra that are already mixed because of birefringence.
Moreover, if the polarization rotation angle increases during propagation,
birefringence affects more the large scales that the small scales. We put
constraints on the two cases using data from WMAP 9yr and BICEP 2013 and
compare these results with the constraints obtained when the usual procedure of
rotating the final power spectra is adopted, finding that this dataset
combination is unable to distinguish between effects, but it nevertheless hints
for a non vanishing value of the polarization rotation angle. We also forecast
the sensitivity that will be obtained using data from Planck and PolarBear,
highlighting how this combination is capable to rule out a vanishing
birefringence angle, but still unable to distinguish the different scenarios.
Nevertheless, we find that the combination of Planck and PolarBear is sensitive
enough to highlight the existence of degeneracies between birefringence
rotation and gravitational lensing of CMB photons, possibly leading to false
detection of non standard lensing effects if birefringence is neglected.
| arxiv topic:astro-ph.CO |
arxiv_dataset-56301410.1899 | Transparent boundary conditions in a Discontinuous Galerkin Trefftz
method
math.NA
The modeling and simulation of electromagnetic wave propagation is often
accompanied by a restriction to bounded domains which requires the introduction
of artificial boundaries. The corresponding boundary conditions should be
chosen in order to minimize parasitic reflections. In this paper, we
investigate a new type of transparent boundary condition for a discontinuous
Galerkin Trefftz finite element method. The choice of a particular basis
consisting of polynomial plane waves allows us to split the electromagnetic
field into components with a well specified direction of propagation. The
reflections at the artificial boundaries are then reduced by penalizing
components of the field incoming into the space-time domain of interest. We
formally introduce this concept, discuss its realization within the
discontinuous Galerkin framework, and demonstrate the performance of the
resulting approximations by numerical tests. A comparison with first order
absorbing boundary conditions, that are frequently used in practice, is made.
For a proper choice of basis functions, we observe spectral convergence in our
numerical test and an overall dissipative behavior for which we also give some
theoretical explanation.
| arxiv topic:math.NA |
arxiv_dataset-56311410.1999 | Ag adatoms on Si(111)5x2-Au surface
cond-mat.mes-hall
Using scanning tunneling microscopy together with the first-principles
density functional theory calculations we study structural properties of the
Si(111)5x2-Au surface covered by Ag adatoms. The STM topography data show that
a submonolayer coverage of Ag does not lead to a well-ordered adatom chain
structure with a periodicity 5x4, as it was observed for Si, Pb and In adatoms.
Instead of that, we observe Ag adatoms located in different nonequivalent
positions within the unit cell, which confirms the electronic nature of
stabilization of the Si(111)5x2-Au surface. Moreover, the DFT calculations give
five different structural models of the Si(111)5x2-Au/Ag surface. All the
models are almost degenerate in energy, which further supports the above
scenario.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-56321410.2099 | FlavorKit: a brief overview
hep-ph
We give a brief overview of FlavorKit, a kit for the study of flavor
observables beyond the standard model. In contrast to previous flavor codes,
FlavorKit is not restricted to a single model, but can be used to obtain
predictions for flavor observables in a wide range of models. FlavorKit can be
used in two different ways. The basic usage of FlavorKit allows for the
computation of a large number of lepton and quark flavor observables, using
generic analytical expressions for the Wilson coefficients of the relevant
operators. The setup is based on the public codes SARAH and SPheno, and thus
allows for the analytical and numerical computation of the observables in the
model defined by the user. If necessary, the user can also go beyond the basic
usage and define his own operators and/or observables. For this purpose, a
Mathematica package called PreSARAH has been developed. This tool uses FeynArts
and FormCalc to compute generic expressions for the required Wilson
coefficients at the tree- and 1-loop levels. Similarly, the user can easily
implement new observables. With all these tools properly combined, the user can
obtain analytical and numerical results for the observables of his interest in
the model of his choice.
| arxiv topic:hep-ph |
arxiv_dataset-56331410.2199 | Expanding and expansive time-dependent dynamics
math.DS
In this paper, time-dependent dynamical systems given by sequences of maps
are studied. For systems built from expanding C^2-maps on a compact Riemannian
manifold M with uniform bounds on expansion factors and derivatives, we provide
formulas for the metric and topological entropy. If we only assume that the
maps are C^1, but act in the same way on the fundamental group of M, we can
show the existence of an equi-conjugacy to an autonomous system, implying a
full variational principle for the entropy. Finally, we introduce the notion of
strong uniform expansivity that generalizes the classical notion of positive
expansivity, and we prove time-dependent analogues of some well-known results.
In particular, we generalize Reddy's result which states that a positively
expansive system locally expands distances in an equivalent metric.
| arxiv topic:math.DS |
arxiv_dataset-56341410.2299 | Testing the Zee-Babu model via neutrino data, lepton flavour violation
and direct searches at the LHC
hep-ph
We discuss how the Zee-Babu model can be tested combining information from
neutrino data, low-energy experiments and direct searches at the LHC. We update
previous analysis in the light of the recent measurement of the neutrino mixing
angle $\theta_{13}$, the new MEG limits on $\mu \rightarrow e \gamma$, the
lower bounds on doubly-charged scalars coming from LHC data, and, of course,
the discovery of a 125 GeV Higgs boson by ATLAS and CMS. In particular, we find
that the new singly- and doubly-charged scalars are accessible at the second
run of the LHC, yielding different signatures depending on the neutrino
hierarchy and on the values of the phases. We also discuss in detail the
stability of the potential.
| arxiv topic:hep-ph |
arxiv_dataset-56351410.2399 | On the interior regularity criteria of the 3-D Navier-Stokes equations
involving two velocity components
math.AP
We present some interior regularity criteria of the 3-D Navier-Stokes
equations involving two components of the velocity. These results in particular
imply that if the solution is singular at one point, then at least two
components of the velocity have to blow up at the same point.
| arxiv topic:math.AP |
arxiv_dataset-56361410.2499 | Energy conservation and dissipation properties of time-integration
methods for the nonsmooth elastodynamics with contact
math.NA
This research report is devoted to the study of the conservation and the
dissipation properties of the mechanical energy of several time--integration
methods dedicated to the elasto--dynamics with unilateral contact. Given that
the direct application of the standard schemes as the Newmark schemes or the
generalized--$\alpha$ schemes leads to energy blow-up, we study two schemes
dedicated to the time--integration of nonsmooth systems with contact: the
Moreau--Jean scheme and the nonsmooth generalized--$\alpha$ scheme. The energy
conservation and dissipation properties of the Moreau--Jean is firstly shown.
In a second step, the nonsmooth generalized--$\alpha$ scheme is studied by
adapting the previous works of Krenk and H{\o}gsberg in the context of
unilateral contact. Finally, the known properties of the Newmark and the
Hilber--Hughes--Taylor (HHT) scheme in the unconstrained case are extended
without any further assumptions to the case with contact.
| arxiv topic:math.NA |
arxiv_dataset-56371410.2599 | Estimates of the cosmic gamma-ray flux at PeV to EeV energies from the
EAS-MSU experiment data
astro-ph.HE
Archival EAS-MSU data are searched for anomalous muonless events which may be
caused by primary gamma rays with energies between 10^15 eV and 10^18 eV. We
consider a refined sample of high-quality data and confirm the previously
reported detection of a non-zero gamma-ray flux at ~5x10^16 eV with a similar
flux value but at somewhat lower statistical significance, corresponding to the
depletion of the sample. We present upper limits on the flux below and above
these energies, including the first constraints in the range (10^17-10^18) eV
never studied by any other experiment.
| arxiv topic:astro-ph.HE |
arxiv_dataset-56381410.2699 | A simple view of the heavy-tailed sales distributions and application to
the box-office grosses of U.S. movies
physics.soc-ph
This letter treats of the power-law distribution of the sales of items. We
propose a simple stochastic model which expresses a selling process of an item.
This model produces a stationary power-law distribution, whose power-law
exponent is analytically derived. Next we compare the model with an actual data
set of movie income. We focus on the return on investment (ROI), defined as the
gross income divided by the production budget. We confirm that the power-law
exponent of ROI distribution can be estimated from the ratios of income between
two adjoining weeks, as predicted by the model analysis. Moreover, exponential
decay of weekly income is observed both in the model and actual income.
Therefore, the proposed model is simple enough, but it can quantitatively
describe the power-law sales distribution.
| arxiv topic:physics.soc-ph |
arxiv_dataset-56391410.2799 | Effect of annealing on the charge-voltage characteristics of the
SrBi2(Ta,Nb)2O9 films
cond-mat.mtrl-sci
The effect of changes of the Nb content and annealing on charge vs. voltage
and current vs. voltage characteristics of SrBi2(Ta,Nb)2O9 film was studied
theoretically and experimentally. Theoretical modeling, which takes into
account the mobile charged donors impact on the features of charge vs. voltage
and current vs. voltage characteristics of ferroelectric semiconductor films,
revealed the changes of conductivity value and ferroelectric parameters. The
results of theoretical analysis and experimental results are in qualitative
agreement.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-56401410.2899 | The Event Horizon Telescope: exploring strong gravity and accretion
physics
astro-ph.HE astro-ph.IM
The Event Horizon Telescope (EHT), a global sub-millimeter wavelength very
long baseline interferometry array, is now resolving the innermost regions
around the supermassive black holes Sgr A* and M87. Using black hole images
from both simple geometric models and relativistic magnetohydrodynamical
accretion flow simulations, we perform a variety of experiments to assess the
promise of the EHT for studying strong gravity and accretion physics during the
stages of its development. We find that (1) the addition of the LMT and ALMA
along with upgraded instrumentation in the "Complete" stage of the EHT allow
detection of the photon ring, a signature of Kerr strong gravity, for predicted
values of its total flux; (2) the inclusion of coherently averaged closure
phases in our analysis dramatically improves the precision of even the current
array, allowing (3) significantly tighter constraints on plausible accretion
models and (4) detections of structural variability at the levels predicted by
the models. While observations at 345 GHz circumvent problems due to
interstellar electron scattering in line-of-sight to the galactic center, short
baselines provided by CARMA and/or the LMT could be required in order to
constrain the overall shape of the accretion flow. Given the systematic
uncertainties in the underlying models, using the full complement of two
observing frequencies (230 and 345 GHz) and sources (Sgr A* and M87) may be
critical for achieving transformative science with the EHT experiment.
| arxiv topic:astro-ph.HE astro-ph.IM |
arxiv_dataset-56411410.2999 | Kepler-432 b: a massive planet in a highly eccentric orbit transiting a
red giant
astro-ph.EP
We report the first disclosure of the planetary nature of Kepler-432 b (aka
Kepler object of interest KOI-1299.01). We accurately constrained its mass and
eccentricity by high-precision radial velocity measurements obtained with the
CAFE spectrograph at the CAHA 2.2-m telescope. By simultaneously fitting these
new data and Kepler photometry, we found that Kepler-432 b is a dense
transiting exoplanet with a mass of Mp = 4.87 +/- 0.48 MJup and radius of Rp =
1.120 +/- 0.036 RJup. The planet revolves every 52.5 d around a K giant star
that ascends the red giant branch, and it moves on a highly eccentric orbit
with e = 0.535 +/- 0.030. By analysing two NIR high-resolution images, we found
that a star is located at 1.1 from Kepler-432, but it is too faint to cause
significant effects on the transit depth. Together with Kepler-56 and
Kepler-91, Kepler-432 occupies an almost-desert region of parameter space,
which is important for constraining the evolutionary processes of planetary
systems.
| arxiv topic:astro-ph.EP |
arxiv_dataset-56421410.3099 | Radiation drag in the field of a non-spherical source
astro-ph.HE gr-qc
The motion of a test particle in the gravitational field of a non-spherical
source endowed with both mass and mass quadrupole moment is investigated when a
test radiation field is also present. The background is described by the
Erez-Rosen solution, which is a static spacetime belonging to the Weyl class of
solutions to the vacuum Einstein's field equations, and reduces to the familiar
Schwarzschild solution when the quadrupole parameter vanishes. The radiation
flux has a fixed but arbitrary (non-zero) angular momentum. The interaction
with the radiation field is assumed to be Thomson-like, i.e., the particles
absorb and re-emit radiation, thus suffering for a friction-like drag force.
Such an additional force is responsible for the Poynting-Robertson effect,
which is well established in the framework of Newtonian gravity and has been
recently extended to the general theory of relativity. The balance between
gravitational attraction, centrifugal force and radiation drag leads to the
occurrence of equilibrium circular orbits which are attractors for the
surrounding matter for every fixed value of the interaction strength. The
presence of the quadrupolar structure of the source introduces a further degree
of freedom: there exists a whole family of equilibrium orbits parametrized by
the quadrupole parameter, generalizing previous works. This scenario is
expected to play a role in the context of accretion matter around compact
objects.
| arxiv topic:astro-ph.HE gr-qc |
arxiv_dataset-56431410.3199 | Applied Neural Cross-Correlation into the Curved Trajectory Detection
Process for Braitenberg Vehicles
cs.RO
Curved Trajectory Detection (CTD) process could be considered among
high-level planned capabilities for cognitive agents, has which been acquired
under aegis of embedded artificial spiking neuronal circuits. In this paper,
hard-wired implementation of the cross-correlation, as the most common
comparison-driven scheme for both natural and artificial bionic constructions
named Depth Detection Module(DDM), has been taken into account. It is
manifestation of efficient handling upon epileptic seizures due to application
of both excitatory and inhibitory connections within the circuit structure.
Presented traditional analytic approach of the cross-correlation computation
with regard to our neural mapping technique and the acquired traced precision
have been turned into account for coherent accomplishments of the
aforementioned design in perspective of the desired accuracy upon high-level
cognitive reactions. Furthermore, the proposed circuit could be fitted into the
scalable neuronal network of the CTD, properly. Simulated denouements have been
captured based on the computational model of PIONEER mobile robot to verify
characteristics of the module, in detail.
| arxiv topic:cs.RO |
arxiv_dataset-56441410.3299 | Quarkonia suppression in PbPb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV
hep-ph nucl-th
We estimate the modification of quarkonia yields due to different processes
in the medium produced in Pb+Pb collisions at LHC energy. The quarkonia and
heavy flavour cross sections calculated up to next-to-leading order (NLO) are
used in the study. Shadowing corrections are obtained with the NLO EPS09
parametrization. A kinetic model is employed which incorporates quarkonia
suppression inside a QGP, suppression due to hadronic comovers, and
regeneration from charm pairs. The quarkonia dissociation cross section due to
gluon collisions has been considered and the regeneration rate has been
obtained using the principle of detailed balance. The modification in quarkonia
yields due to collisions with hadronic comovers has been estimated assuming
that the comovers are pions. The manifestations of these effects on the nuclear
modification factors for both $J/\psi$ and $\Upsilon$ in different kinematic
regions has been demonstrated for Pb+Pb collisions at $\sqrt{s_{_{NN}}}$ = 2.76
TeV in comparison with the measurements. Both the suppression and regeneration
due to a deconfined medium strongly affect the low and intermediate $p_T$
range. The large observed suppression of $J/\psi$ at $p_T~>$ 10 GeV/$c$ exceeds
the estimates of suppression by gluon dissociation.
| arxiv topic:hep-ph nucl-th |
arxiv_dataset-56451410.3399 | From DeWitt initial condition to Cosmological Quantum Entanglement
gr-qc hep-th
A gravity-anti-gravity (GaG) odd linear dilaton action offers an eternal
inflation evolution governed by the unified (cosmological constant plus
radiation) equation of state $\rho-3P=4\Lambda$. At the mini superspace level,
a 'two-particle' variant of the no-boundary proposal, notably 'one-particle'
energy dependent, is encountered. While a GaG-odd wave function can only host a
weak Big Bang boundary condition, albeit for any $k$, a strong Big Bang
boundary condition requires a GaG-even entangled wave function, and singles out
$k=0$ flat space. The locally most probable values for the cosmological scale
factor and the dilaton field form a grid
$\{a^2,a\phi\}\sim\sqrt{4n_1+1}\pm\sqrt{4n_2+1}$.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-56461410.3499 | The spectroscopic Hertzsprung-Russell diagram of Galactic massive stars
astro-ph.SR
The distribution of stars in the Hertzsprung-Russell diagram narrates their
evolutionary history and directly assesses their properties. Placing stars in
this diagram however requires the knowledge of their distances and interstellar
extinctions, which are often poorly known for Galactic stars. The spectroscopic
Hertzsprung-Russell diagram (sHRD) tells similar evolutionary tales, but is
independent of distance and extinction measurements. Based on spectroscopically
derived effective temperatures and gravities of almost 600 stars, we derive for
the first time the observational distribution of Galactic massive stars in the
sHRD. While biases and statistical limitations in the data prevent detailed
quantitative conclusions at this time, we see several clear qualitative trends.
By comparing the observational sHRD with different state-of-the-art stellar
evolutionary predictions, we conclude that convective core overshooting may be
mass-dependent and, at high mass ($\geq 15\,M_\odot$), stronger than previously
thought. Furthermore, we find evidence for an empirical upper limit in the sHRD
for stars with $T_{\rm{eff}}$ between 10000 and 32000 K and, a strikingly large
number of objects below this line. This over-density may be due to inflation
expanding envelopes in massive main-sequence stars near the Eddington limit.
| arxiv topic:astro-ph.SR |
arxiv_dataset-56471410.3599 | On the missing second generation AGB stars in NGC6752
astro-ph.SR
[Abridged] In recent years the view of Galactic globular clusters as simple
stellar populations has changed dramatically, as it is now thought that
basically all GCs host multiple stellar populations, each with its own chemical
abundance pattern and colour-magnitude diagram sequence. Recent spectroscopic
observations of asymptotic giant branch stars in the GC NGC6752 have disclosed
a low [Na/Fe] abundance for the whole sample, suggesting that they are all
first-generation stars, and that all second-generation stars fail to reach the
AGB in this cluster. A scenario proposed to explain these observations invokes
strong mass loss in second-generation horizontal branch stars possibly induced
by the metal enhancement associated to radiative levitation. This enhanced mass
loss would prevent second generation stars from reaching the AGB phase, thus
explaining at the same time the low value of the ratio between HB and AGB stars
(the R_2 parameter) observed in NGC6752. We have critically discussed this
scenario, finding that the required mass-loss rates are of the order of 10^{-9}
Mo/yr, significantly higher than current theoretical and empirical constraints.
By making use of synthetic HB simulations, we demonstrate that our modelling
predicts correctly the R_2 parameter for NGC6752, without the need to invoke
very efficient mass loss during the core He-burning stage. Our simulations for
NGC6752 HB predict however the presence of a significant fraction - at the
level of about 50% - second generation stars along the cluster AGB. We conclude
that there is no simple explanation for the lack of second generation stars in
the spectroscopically surveyed sample, although the interplay between mass loss
(with low rates) and radiative levitation may play a role in explaining this
puzzle.
| arxiv topic:astro-ph.SR |
arxiv_dataset-56481410.3699 | A graph Laplacian regularization for hyperspectral data unmixing
cs.CV
This paper introduces a graph Laplacian regularization in the hyperspectral
unmixing formulation. The proposed regularization relies upon the construction
of a graph representation of the hyperspectral image. Each node in the graph
represents a pixel's spectrum, and edges connect spectrally and spatially
similar pixels. The proposed graph framework promotes smoothness in the
estimated abundance maps and collaborative estimation between homogeneous areas
of the image. The resulting convex optimization problem is solved using the
Alternating Direction Method of Multipliers (ADMM). A special attention is
given to the computational complexity of the algorithm, and Graph-cut methods
are proposed in order to reduce the computational burden. Finally, simulations
conducted on synthetic data illustrate the effectiveness of the graph Laplacian
regularization with respect to other classical regularizations for
hyperspectral unmixing.
| arxiv topic:cs.CV |
arxiv_dataset-56491410.3799 | A new look at the cosmic ray positron fraction
astro-ph.HE
The positron fraction in cosmic rays was found to be a steadily increasing in
function of energy, above $\sim$ 10 GeV. This behaviour contradicts standard
astrophysical mechanisms, in which positrons are secondary particles, produced
in the interactions of primary cosmic rays during the propagation in the
interstellar medium. The observed anomaly in the positron fraction triggered a
lot of excitement, as it could be interpreted as an indirect signature of the
presence of dark matter species in the Galaxy. Alternatively, it could be
produced by nearby astrophysical sources, such as pulsars. Both hypotheses are
probed in this work in light of the latest AMS-02 positron fraction
measurements. The transport of the primary and secondary positrons in the
Galaxy is described using a semi-analytic two-zone model. MicrOMEGAs is used to
model the positron flux generated by dark matter species. The description of
the positron fraction from astrophysical sources is based on the pulsar
observations included in the ATNF catalogue. We find that the mass of the
favoured dark matter candidates is always larger than 500 GeV. The only dark
matter species that fulfils the numerous gamma ray and cosmic microwave
background bounds is a particle annihilating into four leptons through a light
scalar or vector mediator, with a mixture of tau (75%) and electron (25%)
channels, and a mass between 0.5 and 1 TeV. The positron anomaly can also be
explained by a single astrophysical source and a list of five pulsars from the
ATNF catalogue is given. Those results are obtained with the cosmic ray
transport parameters that best fit the B/C ratio. Uncertainties in the
propagation parameters turn out to be very significant. In the WIMP
annihilation cross section to mass plane for instance, they overshadow the
error contours derived from the positron data.
| arxiv topic:astro-ph.HE |
arxiv_dataset-56501410.3899 | Optimal Scheduling of Electric Vehicles Charging in low-Voltage
Distribution Systems
cs.SY
Uncoordinated charging of large-scale electric vehicles (EVs) will have a
negative impact on the secure and economic operation of the power system,
especially at the distribution level. Given that the charging load of EVs can
be controlled to some extent, research on the optimal charging control of EVs
has been extensively carried out. In this paper, two possible smart charging
scenarios in China are studied: centralized optimal charging operated by an
aggregator and decentralized optimal charging managed by individual users.
Under the assumption that the aggregators and individual users only concern the
economic benefits, new load peaks will arise under time of use (TOU) pricing
which is extensively employed in China. To solve this problem, a simple
incentive mechanism is proposed for centralized optimal charging while a
rolling-update pricing scheme is devised for decentralized optimal charging.
The original optimal charging models are modified to account for the developed
schemes. Simulated tests corroborate the efficacy of optimal scheduling for
charging EVs in various scenarios.
| arxiv topic:cs.SY |
arxiv_dataset-56511410.3999 | Systematic trend of water vapour absorption in red giant atmospheres
revealed by high resolution TEXES 12 micron spectra
astro-ph.SR
The structures of the outer atmospheres of red giants are very complex. The
notion of large optically thick molecular spheres around the stars (MOLspheres)
has been invoked in order to explain e.g. spectro-interferometric observations.
However, high-resolution spectra in the mid-IR do not easily fit into this
picture. They rule out any large sphere of water vapour in LTE surrounding red
giants. Our aim here is to investigate high-resolution, mid-infrared spectra
for a range of red giants, from early-K to mid M. We have recorded 12 microns
spectra of 10 well-studied bright red giants, with TEXES on the IRTF. We find
that all giants in our study cooler than 4300 K, spanning a range of effective
temperatures, show water absorption lines stronger than expected. The strengths
of the lines vary smoothly with spectral type. We identify several spectral
features in the wavelength region that undoubtedly are formed in the
photosphere. From a study of water-line ratios of the stars, we find that the
excitation temperatures, in the line-forming regions, are several hundred
Kelvin lower than expected from a classical photospheric model. This could
either be due to an actually lower temperature structure in the outer regions
of the photospheres caused by, for example, extra cooling, or due to non-LTE
level populations, affecting the source function and line opacities. We have
demonstrated that these diagnostically interesting water lines are a general
feature of red giants across spectral types, and we argue for a general
explanation of their formation rather than explanations requiring specific
properties. Since the water lines are neither weak (filled in by emission) nor
appear in emission, as predicted by LTE MOLsphere models in their simplest
forms, the evidence for the existence of such large optically-thick, molecular
spheres enshrouding the stars is weakened. (abbreviated)
| arxiv topic:astro-ph.SR |
arxiv_dataset-56521410.4099 | An upper bound on the k-modem illumination problem
cs.CG
A variation on the classical polygon illumination problem was introduced in
[Aichholzer et. al. EuroCG'09]. In this variant light sources are replaced by
wireless devices called k-modems, which can penetrate a fixed number k, of
"walls". A point in the interior of a polygon is "illuminated" by a k-modem if
the line segment joining them intersects at most k edges of the polygon. It is
easy to construct polygons of n vertices where the number of k-modems required
to illuminate all interior points is Omega(n/k). However, no non-trivial upper
bound is known. In this paper we prove that the number of k-modems required to
illuminate any polygon of n vertices is at most O(n/k). For the cases of
illuminating an orthogonal polygon or a set of disjoint orthogonal segments, we
give a tighter bound of 6n/k + 1. Moreover, we present an O(n log n) time
algorithm to achieve this bound.
| arxiv topic:cs.CG |
arxiv_dataset-56531410.4199 | The Occurrence and Architecture of Exoplanetary Systems
astro-ph.EP
The basic geometry of the Solar System -- the shapes, spacings, and
orientations of the planetary orbits -- has long been a subject of fascination
as well as inspiration for planet formation theories. For exoplanetary systems,
those same properties have only recently come into focus. Here we review our
current knowledge of the occurrence of planets around other stars, their
orbital distances and eccentricities, the orbital spacings and mutual
inclinations in multiplanet systems, the orientation of the host star's
rotation axis, and the properties of planets in binary-star systems.
| arxiv topic:astro-ph.EP |
arxiv_dataset-56541410.4299 | Open chemical reaction networks, steady-state loads and Braess-like
paradox
physics.chem-ph physics.bio-ph
Open chemical reaction systems involve matter-exchange with the surroundings.
As a result, species can accumulate inside a system during the course of the
reaction. We study the role of network topology in governing the concentration
build-up inside a fixed reaction volume at steady state, particularly focusing
on the effect of additional paths. The problem is akin to that in traffic
networks where an extra route, surprisingly, can increase the overall travel
time. This is known as the Braess' paradox. Here, we report chemical analogues
of such a paradox in suitably chosen reaction networks, where extra reaction
step(s) can inflate the total concentration, denoted as `load', at steady
state. It is shown that, such counter-intuitive behavior emerges in a
qualitatively similar pattern in networks of varying complexities. We then
explore how such extra routes affect the load in a biochemical scheme of uric
acid degradation. From a thorough analysis of this network, we propose a
functional role of some decomposition steps that can trim the load, indicating
the importance of the latter in the evolution of reaction mechanisms in living
matter.
| arxiv topic:physics.chem-ph physics.bio-ph |
arxiv_dataset-56551410.4399 | Constrained Runs algorithm as a lifting operator for the Boltzmann
equation
cs.CE
Lifting operators play an important role in starting a kinetic Boltzmann
model from given macroscopic information. The macroscopic variables need to be
mapped to the distribution functions, mesoscopic variables of the Boltzmann
model. A well-known numerical method for the initialization of Boltzmann models
is the Constrained Runs algorithm. This algorithm is used in literature for the
initialization of lattice Boltzmann models, special discretizations of the
Boltzmann equation. It is based on the attraction of the dynamics toward the
slow manifold and uses lattice Boltzmann steps to converge to the desired
dynamics on the slow manifold. We focus on applying the Constrained Runs
algorithm to map density, average flow velocity, and temperature, the
macroscopic variables, to distribution functions. Furthermore, we do not
consider only lattice Boltzmann models. We want to perform the algorithm for
different discretizations of the Boltzmann equation and consider a standard
finite volume discretization.
| arxiv topic:cs.CE |
arxiv_dataset-56561410.4499 | Spectral Noise Correlations of an Ultrafast Frequency Comb
quant-ph
Cavity-based noise detection schemes are combined with ultrafast pulse
shaping as a means to diagnose the spectral correlations of both the amplitude
and phase noise of an ultrafast frequency comb. The comb is divided into ten
spectral regions, and the distribution of noise as well as the correlations
between all pairs of spectral regions are measured against the quantum limit.
These correlations are then represented in the form of classical noise
matrices, which furnish a complete description of the underlying comb dynamics.
Their eigendecomposition reveals a set of theoretically predicted, decoupled
noise modes that govern the dynamics of the comb. Finally, the matrices contain
the information necessary to deduce macroscopic noise properties of the comb.
| arxiv topic:quant-ph |
arxiv_dataset-56571410.4599 | Non-parametric Bayesian Learning with Deep Learning Structure and Its
Applications in Wireless Networks
cs.LG cs.NE cs.NI stat.ML
In this paper, we present an infinite hierarchical non-parametric Bayesian
model to extract the hidden factors over observed data, where the number of
hidden factors for each layer is unknown and can be potentially infinite.
Moreover, the number of layers can also be infinite. We construct the model
structure that allows continuous values for the hidden factors and weights,
which makes the model suitable for various applications. We use the
Metropolis-Hastings method to infer the model structure. Then the performance
of the algorithm is evaluated by the experiments. Simulation results show that
the model fits the underlying structure of simulated data.
| arxiv topic:cs.LG cs.NE cs.NI stat.ML |
arxiv_dataset-56581410.4699 | Deceleration of molecules in a supersonic beam by the optical field in a
low-finesse cavity
physics.atom-ph physics.atm-clus quant-ph
We study the dynamics of a supersonic molecular beam in a low-finesse optical
cavity and demonstrate that most molecules in the beam can be decelerated to
zero central velocity by the intracavity optical field in a process analogous
to electrostatic Stark deceleration. We show that the rapid switching of the
optical field for slowing the molecules is automatically generated by the
cavity-induced dynamics. We further show that $\sim1\%$ of the molecules can be
optically trapped at a few millikelvin in the same cavity.
| arxiv topic:physics.atom-ph physics.atm-clus quant-ph |
arxiv_dataset-56591410.4799 | Simulation of Black Hole Collisions in Asymptotically AdS Spacetimes
hep-th gr-qc nucl-th
We present results from the evolution of spacetimes that describe the merger
of asymptotically global AdS black holes in 5D with an SO(3) symmetry. Prompt
scalar field collapse provides us with a mechanism for producing distinct
trapped regions on the initial slice, associated with black holes initially at
rest. We evolve these black holes towards a merger, and follow the subsequent
ring-down. The boundary stress tensor of the dual CFT is conformally related to
a stress tensor in Minkowski space which inherits an axial symmetry from the
bulk SO(3). We compare this boundary stress tensor to its hydrodynamic
counterpart with viscous corrections of up to second order, and compare the
conformally related stress tensor to ideal hydrodynamic simulations in
Minkowski space, initialized at various time slices of the boundary data. Our
findings reveal far-from-hydrodynamic behavior at early times, with a
transition to ideal hydrodynamics at late times.
| arxiv topic:hep-th gr-qc nucl-th |
arxiv_dataset-56601410.4899 | Non-Gaussian features from Excited Squeezed Vacuum State
quant-ph
In this work, we introduce a non-Gaussian quantum state named excited
squeezed vacuum state (ESVS), which can be ustilized to describe quantum light
field emitted from the multiphoton quantum process occurred in some restricted
quantum systems. We investigate its nonclassical properties such as Wigner
distribution in phase space, photon number distribution, the second-order
autocorrelation and the quadrature fluctuations. By virtue of the
Hilbert-Schmidt distance method, we quantify the non-Gaussianity of the ESVS.
Due to the similar photon statistics, we examine the fidelity between the ESVS
and the photon-subtraction squeezed vacuum state (PSSVS), and then find the
optimal fidelity by monitoring the relevant parameters.
| arxiv topic:quant-ph |
arxiv_dataset-56611410.4999 | Sparticle Mass Hierarchies, Simplified Models from SUGRA Unification,
and Benchmarks for LHC Run-II SUSY Searches
hep-ph hep-ex
Sparticle mass hierarchies contain significant information regarding the
origin and nature of supersymmetry breaking. The hierarchical patterns are
severely constrained by electroweak symmetry breaking as well as by the
astrophysical and particle physics data. They are further constrained by the
Higgs boson mass measurement. The sparticle mass hierarchies can be used to
generate simplified models consistent with the high scale models. In this work
we consider supergravity models with universal boundary conditions for soft
parameters at the unification scale as well as supergravity models with
nonuniversalities and delineate the list of sparticle mass hierarchies for the
five lightest sparticles. Simplified models can be obtained by a truncation of
these, retaining a smaller set of lightest particles. The mass hierarchies and
their truncated versions enlarge significantly the list of simplified models
currently being used in the literature. Benchmarks for a variety of
supergravity unified models appropriate for SUSY searches at future colliders
are also presented. The signature analysis of two benchmark models has been
carried out and a discussion of the searches needed for their discovery at LHC
RUN-II is given. An analysis of the spin independent neutralino-proton cross
section exhibiting the Higgs boson mass dependence and the hierarchical
patterns is also carried out. It is seen that a knowledge of the spin
independent neutralino-proton cross section and the neutralino mass will narrow
down the list of the allowed sparticle mass hierarchies. Thus dark matter
experiments along with analyses for the LHC Run-II will provide strong clues to
the nature of symmetry breaking at the unification scale.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-56621410.5099 | Identifying features in spike trains using binless similarity measures
q-bio.NC
Neurons in the central nervous system communicate with each other with the
help of series of Action Potentials, or spike trains. Various studies have
shown that neurons encode information in different features of spike trains,
such as the fine temporal structure, mean firing rate, synchrony etc. An
important step in understanding the encoding of information by neurons, is to
obtain a reliable measure of correlation between different spike trains. In
this paper, two new binless similarity measures for spike trains are proposed.
The performance of the new measures are compared with some existing measures in
their ability to detect important features of spike trains, such as their
firing rate, sensitivity to bursts and common periods of silence and detecting
synchronous activity.
| arxiv topic:q-bio.NC |
arxiv_dataset-56631410.5199 | Series expansion for the Fourier transform of a rational function in
three dimensions
math-ph cond-mat.quant-gas math.MP
In Rashba-Dresselhaus spin-orbit coupled systems, the calculation of Green's
function requires the knowledge of the inverse Fourier transform of rational
function $P(p)/Q(p)$, where $P(p)$ takes the values $1$ and $p^{2}$, and where
\[ Q(p)=(p^{2}-\zeta)^{2}- \alpha^{2}(p_{1}^{2}+p_{2}^{2})-\beta^{2} \] with
suitable parameters $\alpha$, $\beta\geq0$, $\zeta\in\mathbb{C}$. While a
two-dimensional problem, with $p=(p_{1},p_{2})$, has been recently solved [J.
Br\"{u}ning et al, J. Phys. A: Math. Theor. 40 (2007)], its three-dimensional
analogue, with $p=(p_{1},p_{2},p_{3})$, remains open. In this paper, a
hypergeometric series expansion for the triple integral is provided.
Convergence of the series dependent on the parameters is studied in detail.
| arxiv topic:math-ph cond-mat.quant-gas math.MP |
arxiv_dataset-56641410.5299 | Self-averaging characteristics of spectral fluctuations
nlin.CD
The spectral form factor as well as the two-point correlator of the density
of (quasi-)energy levels of individual quantum dynamics are not self-averaging.
Only suitable smoothing turns them into useful characteristics of spectra. We
present numerical data for a fully chaotic kicked top, employing two types of
smoothing: one involves primitives of the spectral correlator, the second a
small imaginary part of the quasi-energy. Self-averaging universal (like the
CUE average) behavior is found for the smoothed correlator, apart from noise
which shrinks like $1\over\sqrt N$ as the dimension $N$ of the quantum Hilbert
space grows. There are periodically repeated quasi-energy windows of
correlation decay and revival wherein the smoothed correlation remains finite
as $N\to\infty$ such that the noise is negligible. In between those windows
(where the CUE averaged correlator takes on values of the order ${1\over N^2}$)
the noise becomes dominant and self-averaging is lost. We conclude that the
noise forbids distinction of CUE and GUE type behavior. Surprisingly, the
underlying smoothed generating function does not enjoy any self-averaging
outside the range of its variables relevant for determining the two-point
correlator (and certain higher-order ones). --- We corroborate our numerical
findings for the noise by analytically determining the CUE variance of the
smoothed single-matrix correlator.
| arxiv topic:nlin.CD |
arxiv_dataset-56651410.5399 | Metal-Insulator Transition and Lattice Instability of Paramagnetic V2O3
cond-mat.str-el
We determine the electronic structure and phase stability of paramagnetic
V$_2$O$_3$ at the Mott-Hubbard metal-insulator phase transition, by employing a
combination of an ab initio method for calculating band structures with
dynamical mean-field theory. The structural transformation associated with the
metal-insulator transition is found to occur upon a slight expansion of the
lattice volume by $\sim 1.5$ %, in agreement with experiment. Our results show
that the structural change precedes the metal-insulator transition, implying a
complex interplay between electronic and lattice degrees of freedom at the
transition. Electronic correlations and full charge self-consistency are found
to be crucial for a correct description of the properties of V$_2$O$_3$.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-56661410.5499 | Location Verification Systems Under Spatially Correlated Shadowing
cs.IT math.IT
The verification of the location information utilized in wireless
communication networks is a subject of growing importance. In this work we
formally analyze, for the first time, the performance of a wireless Location
Verification System (LVS) under the realistic setting of spatially correlated
shadowing. Our analysis illustrates that anticipated levels of correlated
shadowing can lead to a dramatic performance improvement of a Received Signal
Strength (RSS)-based LVS. We also analyze the performance of an LVS that
utilizes Differential Received Signal Strength (DRSS), formally proving the
rather counter-intuitive result that a DRSS-based LVS has identical performance
to that of an RSS-based LVS, for all levels of correlated shadowing. Even more
surprisingly, the identical performance of RSS and DRSS-based LVSs is found to
hold even when the adversary does not optimize his true location. Only in the
case where the adversary does not optimize all variables under her control, do
we find the performance of an RSS-based LVS to be better than a DRSS-based LVS.
The results reported here are important for a wide range of emerging wireless
communication applications whose proper functioning depends on the authenticity
of the location information reported by a transceiver.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-56671410.5599 | Chaotic properties of spin lattices near second-order phase transitions
nlin.CD cond-mat.stat-mech
We perform a numerical investigation of the Lyapunov spectra of chaotic
dynamics in lattices of classical spins in the vicinity of second-order
ferromagnetic and antiferromagnetic phase transitions. On the basis of this
investigation, we identify a characteristic of the shape of the Lyapunov
spectra, the "G-index", which exhibits a sharp peak as a function of
temperature at the phase transition, provided the order parameter is capable of
sufficiently strong dynamic fluctuations. As a part of this work, we also
propose a general numerical algorithm for determining the temperature in
many-particle systems, where kinetic energy is not defined.
| arxiv topic:nlin.CD cond-mat.stat-mech |
arxiv_dataset-56681410.5699 | Symmetric operads in abstract symmetric spectra
math.AT math.AG math.KT
This paper sets up the foundations for derived algebraic geometry,
Goerss--Hopkins obstruction theory, and the construction of commutative ring
spectra in the abstract setting of operadic algebras in symmetric spectra in an
(essentially) arbitrary model category.
We show that one can do derived algebraic geometry a la To\"en--Vezzosi in an
abstract category of spectra. We also answer in the affirmative a question of
Goerss and Hopkins by showing that the obstruction theory for operadic algebras
in spectra can be done in the generality of spectra in an (essentially)
arbitrary model category. We construct strictly commutative simplicial ring
spectra representing a given cohomology theory and illustrate this with a
strictly commutative motivic ring spectrum representing higher order products
on Deligne cohomology.
These results are obtained by first establishing Smith's stable positive
model structure for abstract spectra and then showing that this category of
spectra possesses excellent model-theoretic properties: we show that all
colored symmetric operads in symmetric spectra valued in a symmetric monoidal
model category are admissible, i.e., algebras over such operads carry a model
structure. This generalizes the known model structures on commutative ring
spectra and E-infinity ring spectra in simplicial sets or motivic spaces. We
also show that any weak equivalence of operads in spectra gives rise to a
Quillen equivalence of their categories of algebras. For example, this extends
the familiar strictification of E-infinity rings to commutative rings in a
broad class of spectra, including motivic spectra. We finally show that
operadic algebras in Quillen equivalent categories of spectra are again Quillen
equivalent.
| arxiv topic:math.AT math.AG math.KT |
arxiv_dataset-56691410.5799 | Primitive permutation groups and derangements of prime power order
math.GR
Let $G$ be a transitive permutation group on a finite set of size at least
$2$. By a well known theorem of Fein, Kantor and Schacher, $G$ contains a
derangement of prime power order. In this paper, we study the finite primitive
permutation groups with the extremal property that the order of every
derangement is an $r$-power, for some fixed prime $r$. First we show that these
groups are either almost simple or affine, and we determine all the almost
simple groups with this property. We also prove that an affine group $G$ has
this property if and only if every two-point stabilizer is an $r$-group. Here
the structure of $G$ has been extensively studied in work of Guralnick and
Wiegand on the multiplicative structure of Galois field extensions, and in
later work of Fleischmann, Lempken and Tiep on $r'$-semiregular pairs.
| arxiv topic:math.GR |
arxiv_dataset-56701410.5899 | A Fast and Scalable Method for A-Optimal Design of Experiments for
Infinite-dimensional Bayesian Nonlinear Inverse Problems
math.OC stat.CO stat.ME
We address the problem of optimal experimental design (OED) for Bayesian
nonlinear inverse problems governed by PDEs. The goal is to find a placement of
sensors, at which experimental data are collected, so as to minimize the
uncertainty in the inferred parameter field. We formulate the OED objective
function by generalizing the classical A-optimal experimental design criterion
using the expected value of the trace of the posterior covariance. We seek a
method that solves the OED problem at a cost (measured in the number of forward
PDE solves) that is independent of both the parameter and sensor dimensions. To
facilitate this, we construct a Gaussian approximation to the posterior at the
maximum a posteriori probability (MAP) point, and use the resulting covariance
operator to define the OED objective function. We use randomized trace
estimation to compute the trace of this (implicitly defined) covariance
operator. The resulting OED problem includes as constraints the PDEs
characterizing the MAP point, and the PDEs describing the action of the
covariance operator to vectors. The sparsity of the sensor configurations is
controlled using sparsifying penalty functions. We elaborate our OED method for
the problem of determining the sensor placement to best infer the coefficient
of an elliptic PDE. Adjoint methods are used to compute the gradient of the
PDE-constrained OED objective function. We provide numerical results for
inference of the permeability field in a porous medium flow problem, and
demonstrate that the number of PDE solves required for the evaluation of the
OED objective function and its gradient is essentially independent of both the
parameter and sensor dimensions. The number of quasi-Newton iterations for
computing an OED also exhibits the same dimension invariance properties.
| arxiv topic:math.OC stat.CO stat.ME |
arxiv_dataset-56711410.5999 | Diamagnetism and the dispersion of the magnetic permeability
cond-mat.other
It is well known that the usual Kramers--Kronig relations for the relative
permeability function $\mu(\omega)$ are not compatible with diamagnetism
($\mu(0)<1$) and a positive imaginary part ($\text{Im}\,\mu(\omega)>0$ for
$\omega>0$). We demonstrate that a certain physical meaning can be attributed
to $\mu$ for all frequencies, and that in the presence of spatial dispersion,
$\mu$ does not necessarily tend to 1 for high frequencies $\omega$ and fixed
wavenumber $\mathbf k$. Taking the asymptotic behavior into account,
diamagnetism can be compatible with Kramers--Kronig relations even if the
imaginary part of the permeability is positive. We provide several examples of
diamagnetic media and metamaterials for which $\mu(\omega,\mathbf k)\not\to 1$
as $\omega\to\infty$.
| arxiv topic:cond-mat.other |
arxiv_dataset-56721410.6099 | Model-Independent Production of a Top-Philic Resonance at the LHC
hep-ph hep-ex
We investigate the collider phenomenology of a color-singlet vector
resonance, which couples to the heaviest quarks, the top quarks, but very
weakly to the rest of the fermions in the Standard Model. We find that the
dominant production of such a resonance does not appear at the tree level -- it
rather occurs at the one-loop level in association with an extra jet.
Signatures like t anti-t plus jets readily emerge as a result of the subsequent
decay of the resonance into a pair of top quarks. Without the additional jet,
the resonance can still be produced off-shell, which gives a sizeable
contribution at low masses. The lower top quark multiplicity of the loop
induced resonance production facilitates its reconstruction as compared to the
tree level production that gives rise to more exotic signatures involving three
or even four top quarks in the final state. For all these cases, we discuss the
constraints on the resonance production stemming from recent experimental
measurements in the top quark sector. We find that the top-philic vector
resonance remains largely unconstrained for the majority of the parameter
space, although this will be scrutinized closely in the Run 2 phase of the LHC.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-56731410.6199 | The strong Kervaire invariant problem in dimension 62
math.AT math.GT
Using a Toda bracket computation $\langle \theta_4, 2, \sigma^2\rangle$ due
to Daniel C. Isaksen [11], we investigate the $45$-stem more thoroughly. We
prove that $\theta_4^2=0$ using a $4$-fold Toda bracket. By [2], this implies
that $\theta_5$ exists and there exists a $\theta_5$ such that $2\theta_5=0$.
Based on $\theta_4^2=0$, we simplify significantly the $9$-cell complex
construction in [1] to a $4$-cell complex, which leads to another proof that
$\theta_5$ exists.
| arxiv topic:math.AT math.GT |
arxiv_dataset-56741410.6299 | A few remarks on bounded operators on topological vector spaces
math.FA
We give a few observations on different types of bounded operators on a
topological vector space X and their relations with compact operators on X. In
particular, we investigate when these bounded operators coincide with compact
operators. We also consider similar types of bounded bilinear mappings between
topological vector spaces. Some properties of tensor product operators between
locally convex spaces are established. In the last part of the paper we deal
with operators on topological Riesz spaces.
| arxiv topic:math.FA |
arxiv_dataset-56751410.6399 | Negative magnetoresistivity in chiral fluids and holography
hep-th cond-mat.str-el hep-ph
In four dimensions Weyl fermions possess a chiral anomaly which leads to
several special features in the transport phenomena, such as the negative
longitudinal magnetoresistivity. In this paper, we study its inverse, the
longitudinal magnetoconductivity, in the case of a chiral anomalous system with
a background magnetic field B using the linear response method in the
hydrodynamic limit and from holography. Our hydrodynamic results show that in
general we need to have energy, momentum and charge dissipations to get a
finite DC longitudinal magnetoconductivity due to the existence of the chiral
anomaly. Applying the formula that we get from hydrodynamics to the holographic
system in the probe limit, we find that the result in the hydrodynamic regime
matches that calculated from holography via Kubo formula. The holographic
result shows that in an intermediate regime of B there is naturally a negative
magnetoresistivity which decreases as 1/B. At small B direct calculations in
the holographic system suggest that holography provides a new explanation for
the small B positive magnetoresistivity behavior seen in experiment, i.e. the
small B behavior comes from the quantum critical conductivity being affected by
the chiral anomaly.
| arxiv topic:hep-th cond-mat.str-el hep-ph |
arxiv_dataset-56761410.6499 | The contact theorem for charged fluids: from planar to curved geometries
cond-mat.stat-mech cond-mat.soft
When a Coulombic fluid is confined between two parallel charged plates, an
exact relation links the difference of ionic densities at contact with the
plates, to the surface charges of these boundaries. It no longer applies when
the boundaries are curved, and we work out how it generalizes when the fluid is
confined between two concentric spheres (or cylinders), in two and in three
space dimensions. The analysis is thus performed within the cell model picture.
The generalized contact relation opens the possibility to derive new exact
expressions, of particular interest in the regime of strong coulombic
couplings. Some emphasis is put on cylindrical geometry, for which we discuss
in depth the phenomenon of counter-ion evaporation/condensation, and obtain
novel results. Good agreement is found with Monte Carlo simulation data.
| arxiv topic:cond-mat.stat-mech cond-mat.soft |
arxiv_dataset-56771410.6599 | Modeling-based determination of physiological parameters of systemic
VOCs by breath gas analysis: a pilot study
q-bio.QM
In this paper we develop a simple two compartment model which extends the
Farhi equation to the case when the inhaled concentration of a volatile organic
compound (VOC) is not zero. The model connects the exhaled breath concentration
of systemic VOCs with physiological parameters such as endogenous production
rates and metabolic rates. Its validity is tested with data obtained for
isoprene and inhaled deuterated isoprene-D5.
| arxiv topic:q-bio.QM |
arxiv_dataset-56781410.6699 | Backgrounds and sensitivity of the NEXT double beta decay experiment
physics.ins-det hep-ex nucl-ex
NEXT (Neutrino Experiment with a Xenon TPC) is a neutrinoless double-beta
(\beta \beta 0\nu) decay experiment that will operate at the Canfranc
Underground Laboratory (LSC). It is an electroluminescent high-pressure gaseous
xenon Time Projection Chamber (TPC) with separate read-out planes for
calorimetry and tracking. Energy resolution and background suppression are the
two key features of any neutrinoless double beta decay experiment. NEXT has
both good energy resolution (<1% FWHM) at the Q value of $^{136} $Xe and an
extra handle for background identification provided by track reconstruction.
With the background model of NEXT, based on the detector simulation and the
evaluation of the detector radiopurity, we can determine the sensitivity to a
measurement of the \beta\beta 2\nu\ mode in NEW and to a \beta\beta 0\nu\
search in NEXT100. In this way we can predict the background rate of $
5\times10^{-4}\ $counts/(keV kg yr), and a sensitivity to the Majorana neutrino
mass down to 100 meV after a 5-years run of NEXT100.
| arxiv topic:physics.ins-det hep-ex nucl-ex |
arxiv_dataset-56791410.6799 | Physical Conditions in the X-ray Emission-line Gas in NGC 1068
astro-ph.GA
We present a detailed, photoionization modeling analysis of
XMM-Newton/Reflection Grating Spectrometer observations of the Seyfert 2 galaxy
NGC 1068. The spectrum, previously analyzed by Kinkhabwala et al. (2002),
reveals a myriad of soft-Xray emission lines, including those from H- and
He-like carbon, nitrogen, oxygen, and neon, and M- and L-shell iron. As noted
in the earlier analysis, based on the narrowness of the radiative recombination
continua, the electron temperatures in the emission-line gas are consistent
with photoionization, rather than collisional ionization. The strengths of the
carbon and nitrogen emission lines, relative to those of oxygen, suggest
unusual elemental abundances, which we attribute to star-formation history of
the host galaxy. Overall, the emission-lines are blue-shifted with respect to
systemic, with radial velocities ~ 160 km/s, similar to that of [O III] 5007,
and thus consistent with the kinematics and orientation of the optical
emission-line gas and, hence, likely part of an AGN-driven outflow. We were
able to achieve an acceptable fit to most of the strong emission-lines with a
two-component photoionization model, generated with Cloudy. The two components
have ionization parameters and column densities of logU = -0.05 and 1.22, and
logN(H) = 20.85 and 21.2, and covering factors of 0.35 and 0.84, respectively.
The total mass of the X-ray gas is roughly of an order of magnitude greater
than the mass of ionized gas determined from optical and near-IR spectroscopy,
which indicates that it may be the dominant component of the narrow line
region. Furthermore, we suggest that the medium which produces the
scattered/polarized optical emission in NGC~1068 possesses similar physical
characteristics to those of the more highly-ionized of the X-ray model
components.
| arxiv topic:astro-ph.GA |
arxiv_dataset-56801410.6899 | Bose-Einstein condensate strings
gr-qc astro-ph.HE cond-mat.other hep-ph
We consider the possible existence of gravitationally bound general
relativistic strings consisting of Bose-Einstein condensate (BEC) matter which
is described, in the Newtonian limit, by the zero temperature time-dependent
nonlinear Schr\"odinger equation (the Gross-Pitaevskii equation), with
repulsive interparticle interactions. In the Madelung representation of the
wave function, the quantum dynamics of the condensate can be formulated in
terms of the classical continuity equation and the hydrodynamic Euler
equations. In the case of a condensate with quartic nonlinearity, the
condensates can be described as a gas with two pressure terms, the interaction
pressure, which is proportional to the square of the matter density, and the
quantum pressure, which is without any classical analogue though, when the
number of particles in the system is high enough, the latter may be neglected.
Assuming cylindrical symmetry, we analyze the physical properties of the BEC
strings in both the interaction pressure and quantum pressure dominated limits,
by numerically integrating the gravitational field equations. In this way we
obtain a large class of stable stringlike astrophysical objects, whose basic
parameters (mass density and radius) depend sensitively on the mass and
scattering length of the condensate particle, as well as on the quantum
pressure of the Bose-Einstein gas.
| arxiv topic:gr-qc astro-ph.HE cond-mat.other hep-ph |
arxiv_dataset-56811410.6999 | Anomalous magnetic ground state in LaAlO3/SrTiO3 interface probed by
transport through nanowires
cond-mat.mes-hall cond-mat.str-el cond-mat.supr-con
Resistance as a function of temperature down to 20mK and magnetic fields up
to 18T for various carrier concentrations is measured for nanowires made from
the SrTiO3/LaAlO3 interface using a hard mask shadow deposition technique. The
narrow width of the wires (of the order of 50nm) allows us to separate out the
magnetic effects from the dominant superconducting ones at low magnetic fields.
At this regime hysteresis loops are observed along with the superconducting
transition. From our data analysis we find that the magnetic order probed by
the giant magnetoresistance (GMR) effect vanishes at TCurie = 954 mK. This
order is not a simple ferromagnetic state but consists of domains with opposite
magnetization having a preferred in-plane orientation.
| arxiv topic:cond-mat.mes-hall cond-mat.str-el cond-mat.supr-con |
arxiv_dataset-56821410.7099 | Rationality of motivic zeta function and cut-and-paste problem
math.AG
Assuming the positive solution to the Cut-and-paste problem we prove that the
motivic zeta function remains irrational after inverting L.
| arxiv topic:math.AG |
arxiv_dataset-56831410.7199 | The stickiness of micrometer-sized water-ice particles
astro-ph.EP
Water ice is one of the most abundant materials in dense molecular clouds and
in the outer reaches of protoplanetary disks. In contrast to other materials
(e.g., silicates) water ice is assumed to be stickier due to its higher
specific surface energy, leading to faster or more efficient growth in mutual
collisions. However, experiments investigating the stickiness of water ice have
been scarce, particularly in the astrophysically relevant micrometer-size
region and at low temperatures. In this work, we present an experimental setup
to grow aggregates composed of $\mathrm{\mu}$m-sized water-ice particles, which
we used to measure the sticking and erosion thresholds of the ice particles at
different temperatures between $114 \, \mathrm{K}$ and $260 \, \mathrm{K}$. We
show with our experiments that for low temperatures (below $\sim 210 \,
\mathrm{K}$), $\mathrm{\mu}$m-sized water-ice particles stick below a threshold
velocity of $9.6 \, \mathrm{m \, s^{-1}}$, which is approximately ten times
higher than the sticking threshold of $\mathrm{\mu}$m-sized silica particles.
Furthermore, erosion of the grown ice aggregates is observed for velocities
above $15.3 \, \mathrm{m \, s^{-1}}$. A comparison of the experimentally
derived sticking threshold with model predictions is performed to determine
important material properties of water ice, i.e., the specific surface energy
and the viscous relaxation time. Our experimental results indicate that the
presence of water ice in the outer reaches of protoplanetary disks can enhance
the growth of planetesimals by direct sticking of particles.
| arxiv topic:astro-ph.EP |
arxiv_dataset-56841410.7299 | Scaling behavior of the thermopower of the archetypical heavy-fermion
metal $\rm{YbRh_2Si_2}$
cond-mat.str-el
We reveal and explain a scaling behavior of the thermopower $S/T$ exhibiting
by the archetypical heavy-fermion (HF) metal $\rm{YbRh_2Si_2}$ under the
application of magnetic field $B$ at temperatures $T$. We show that the same
scaling is demonstrated by such different HF compounds as $\beta$-${\rm
YbAlB_4}$ and the strongly correlated layered cobalt oxide $\rm
[BiBa_{0.66}K_{0.36}O_{2}]CoO_{2}$. Using $\rm{YbRh_2Si_2}$ as an example, we
demonstrate that the scaling behavior of $S/T$ is violated at the
antiferromagnetic phase transition, while both the residual resistivity
$\rho_0$ and the density of states $N$ experience jumps at the phase
transition, making the thermopower experience two jumps and change its sign.
Our elucidation is based on flattening of the single-particle spectrum that
profoundly affects $\rho_0$ and $N$. To depict the main features of the $S/T$
behavior, we construct the $T-B$ schematic phase diagram of $\rm{YbRh_2Si_2}$.
Our calculated $S/T$ for the HF compounds are in good agreement with
experimental facts and support our observations.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-56851410.7399 | Constraining duty cycles through a Bayesian technique
astro-ph.IM astro-ph.HE
The duty cycle (DC) of astrophysical sources is generally defined as the
fraction of time during which the sources are active. However, DCs are
generally not provided with statistical uncertainties, since the standard
approach is to perform Monte Carlo bootstrap simulations to evaluate them,
which can be quite time consuming for a large sample of sources. As an
alternative, considerably less time-consuming approach, we derived the
theoretical expectation value for the DC and its error for sources whose state
is one of two possible, mutually exclusive states, inactive (off) or flaring
(on), as based on a finite set of independent observational data points.
Following a Bayesian approach, we derived the analytical expression for the
posterior, the conjugated distribution adopted as prior, and the expectation
value and variance. We applied our method to the specific case of the
inactivity duty cycle (IDC) for supergiant fast X-ray transients. We also
studied IDC as a function of the number of observations in the sample. Finally,
we compare the results with the theoretical expectations. We found excellent
agreement with our findings based on the standard bootstrap method. Our
Bayesian treatment can be applied to all sets of independent observations of
two-state sources, such as active galactic nuclei, X-ray binaries, etc. In
addition to being far less time consuming than bootstrap methods, the
additional strength of this approach becomes obvious when considering a
well-populated class of sources ($N_{\rm src} \geq 50$) for which the prior can
be fully characterized by fitting the distribution of the observed DCs for all
sources in the class, so that, through the prior, one can further constrain the
DC of a new source by exploiting the information acquired on the DC
distribution derived from the other sources. [Abridged]
| arxiv topic:astro-ph.IM astro-ph.HE |
arxiv_dataset-56861410.7499 | Ultrafast THz Faraday Rotation in Graphene
cond-mat.mtrl-sci cond-mat.mes-hall
Terahertz (THz) Faraday rotation measurements were performed to investigate
carrier dynamics in p-type CVD graphene. We used static and time-resolved
polarization-sensitive THz transmission measurements in a magnetic field to
probe free carriers in GaAs, InP and Graphene. Static measurements probe the
equilibrium carrier density and momentum scattering rate. Time-resolved
(optical pump/THz probe) measurements probe the change in these quantities
following photoexcitation. In a typical CVD graphene sample we found that 0.5ps
following photoexcitation with 1*10^13 photons/cm2 pulses at 800nm the
effective hole scattering time decreased from 37fs to 34.5fs, while the carrier
concentration increased from 2.0*10^12/cm2 to 2.04*10^12/cm2, leading to a
transient decrease in the conductivity of the film.
| arxiv topic:cond-mat.mtrl-sci cond-mat.mes-hall |
arxiv_dataset-56871410.7599 | Approximate Noether gauge symmetries of Bardeen model
gr-qc
We investigate the approximate Noether gauge symmetries of the geodesic
Lagrangian for the Bardeen spacetime model. This is accommodated by a set of
new approximate Noether gauge symmetry relations for the perturbed geodesic
Lagrangian in the spacetime. A detailed analysis to the spacetime of Bardeen
model up to third-order approximate Noether gauge symmetries is presented.
| arxiv topic:gr-qc |
arxiv_dataset-56881410.7699 | Energy conservation for a radiating charge in classical electrodynamics
physics.class-ph
It is shown that the well-known disparity in classical electrodynamics
between the power radiated in electromagnetic fields and the power-loss, as
calculated from the radiation reaction on a charge undergoing a non-uniform
motion, is successfully resolved when a proper distinction is made between
quantities expressed in terms of a "real time" and those expressed in terms of
a retarded time. It is shown that the expression for the real-time radiative
power loss from a charged particle is somewhat different from the familiar
Larmor's formula, or in a relativistic case, from Li\'{e}nard's formula.
| arxiv topic:physics.class-ph |
arxiv_dataset-56891410.7799 | Dynamic Model Averaging in Large Model Spaces Using Dynamic Occam's
Window
stat.CO q-fin.ST
Bayesian model averaging has become a widely used approach to accounting for
uncertainty about the structural form of the model generating the data. When
data arrive sequentially and the generating model can change over time, Dynamic
Model Averaging (DMA) extends model averaging to deal with this situation.
Often in macroeconomics, however, many candidate explanatory variables are
available and the number of possible models becomes too large for DMA to be
applied in its original form. We propose a new method for this situation which
allows us to perform DMA without considering the whole model space, but using a
subset of models and dynamically optimizing the choice of models at each point
in time. This yields a dynamic form of Occam's window. We evaluate the method
in the context of the problem of nowcasting GDP in the Euro area. We find that
its forecasting performance compares well that of other methods.
Keywords: Bayesian model averaging; Model uncertainty; Nowcasting; Occam's
window.
| arxiv topic:stat.CO q-fin.ST |
arxiv_dataset-56901410.7899 | Incidences between points and generalized spheres over finite fields and
related problems
math.CO
Let $\mathbb{F}_q$ be a finite field of $q$ elements where $q$ is a large odd
prime power and $Q =a_1 x_1^{c_1}+...+a_dx_d^{c_d}\in
\mathbb{F}_q[x_1,...,x_d]$, where $2\le c_i\le N$, $\gcd(c_i,q)=1$, and $a_i\in
\mathbb{F}_q$ for all $1\le i\le d$. A $Q$-sphere is a set of the form $\lbrace
x\in \mathbb{F}_q^d | Q(x-b)=r\rbrace$, where $b\in \mathbb{F}_q^d, r\in
\mathbb{F}_q$. We prove bounds on the number of incidences between a point set
$\mathcal{P}$ and a $Q$-sphere set $\mathcal{S}$, denoted by
$I(\mathcal{P},\mathcal{S})$, as the following.
$$| I(\mathcal{P},\mathcal{S})-\frac{|\mathcal{P}||\mathcal{S}|}{q}|\le
q^{d/2}\sqrt{|\mathcal{P}||\mathcal{S}|}.$$
We prove this estimate by studying the spectra of directed graphs. We also
give a version of this estimate over finite rings $\mathbb{Z}_q$ where $q$ is
an odd integer. As a consequence of the above bounds, we give an estimate for
the pinned distance problem. In Sections $4$ and $5$, we prove a bound on the
number of incidences between a random point set and a random $Q$-sphere set in
$\mathbb{F}_q^d$. We also study the finite field analogues of some
combinatorial geometry problems, namely, the number of generalized isosceles
triangles, and the existence of a large subset without repeated generalized
distances.
| arxiv topic:math.CO |
arxiv_dataset-56911410.7999 | Spectral dimensions from the spectral action
hep-th
The generalised spectral dimension $D_{ S}(T)$ provides a powerful tool for
comparing different approaches to quantum gravity. In this work, we apply this
formalism to the classical spectral actions obtained within the framework of
almost-commutative geometry. Analysing the propagation of spin-0, spin-1 and
spin-2 fields, we show that a non-trivial spectral dimension arises already at
the classical level. The effective field theory interpretation of the spectral
action yields plateau-structures interpolating between a fixed spin-independent
$D_{ S}(T) = d_S$ for short and $D_{ S}(T) = 4$ for long diffusion times $T$.
Going beyond effective field theory
the spectral dimension is completely dominated by the high-momentum
properties of the spectral action, yielding $D_{ S}(T)=0$ for all spins. Our
results support earlier claims that high-energy bosons do not propagate.
| arxiv topic:hep-th |
arxiv_dataset-56921410.8099 | Analyzing User Activities, Demographics, Social Network Structure and
User-Generated Content on Instagram
cs.SI physics.soc-ph
Instagram is a relatively new form of communication where users can instantly
share their current status by taking pictures and tweaking them using filters.
It has seen a rapid growth in the number of users as well as uploads since it
was launched in October 2010. Inspite of the fact that it is the most popular
photo sharing application, it has attracted relatively less attention from the
web and social media research community. In this paper, we present a
large-scale quantitative analysis on millions of users and pictures we crawled
over 1 month from Instagram. Our analysis reveals several insights on Instagram
which were never studied before: 1) its social network properties are quite
different from other popular social media like Twitter and Flickr, 2) people
typically post once a week, and 3) people like to share their locations with
friends. To the best of our knowledge, this is the first in-depth analysis of
user activities, demographics, social network structure and user-generated
content on Instagram.
| arxiv topic:cs.SI physics.soc-ph |
arxiv_dataset-56931410.8199 | Some classification results for generalized q-gaussian algebras
math.OA
To any trace preserving action $\sigma: G \curvearrowright A$ of a countable
discrete group on a finite von Neumann algebra $A$ and any orthogonal
representation $\pi:G \to \mathcal O(\ell^2_{\mathbb{R}}(G))$, we associate the
generalized q-gaussian von Neumann algebra $A \rtimes_{\sigma}
\Gamma_q^{\pi}(G,K)$, where $K$ is an infinite dimensional separable Hilbert
space. Specializing to the cases of $\pi$ being trivial or given by
conjugation, we then prove that if $G \curvearrowright A = L^{\infty}(X)$, $G'
\curvearrowright B = L^{\infty}(Y)$ are p.m.p. free ergodic rigid actions, the
commutator subgroups $[G,G]$, $[G',G']$ are ICC, and $G, G'$ belong to a fairly
large class of groups (including all non-amenable groups having the Haagerup
property), then $A \rtimes \Gamma_q(G,K) = B \rtimes \Gamma_q(G',K')$ implies
that $\mathcal R(G \curvearrowright A)$ is stably isomorphic to $\mathcal R(G'
\curvearrowright B)$, where $\mathcal R(G \curvearrowright A), \mathcal R(G'
\curvearrowright B)$ are the countable, p.m.p. equivalence relations
implemented by the actions of $G$ and $G'$ on $A$ and $B$, respectively. Using
results of D. Gaboriau and S. Popa we construct continuously many pair-wise
non-isomorphic von Neumann algebras of the form $L^{\infty}(X) \rtimes
\Gamma_q(\mathbb{F}_n,K)$, for suitable free ergodic rigid p.m.p. actions
$\mathbb{F}_n \curvearrowright X$.
| arxiv topic:math.OA |
arxiv_dataset-56941410.8299 | The Whitham Equation as a Model for Surface Water Waves
physics.flu-dyn math-ph math.MP
The Whitham equation was proposed as an alternate model equation for the
simplified description of uni-directional wave motion at the surface of an
inviscid fluid. As the Whitham equation incorporates the full linear dispersion
relation of the water wave problem, it is thought to provide a more faithful
description of shorter waves of small amplitude than traditional long wave
models such as the KdV equation.
In this work, we identify a scaling regime in which the Whitham equation can
be derived from the Hamiltonian theory of surface water waves. The Whitham
equation is integrated numerically, and it is shown that the equation gives a
close approximation of inviscid free surface dynamics as described by the Euler
equations. The performance of the Whitham equation as a model for free surface
dynamics is also compared to two standard free surface models: the KdV and the
BBM equation. It is found that in a wide parameter range of amplitudes and
wavelengths, the Whitham equation performs on par with or better than both the
KdV and BBM equations.
| arxiv topic:physics.flu-dyn math-ph math.MP |
arxiv_dataset-56951410.8399 | X-ray absorption spectroscopy study of the electronic and magnetic
proximity effects in YBa$_2$Cu$_3$O$_{7}$/La$_{2/3}$Ca$_{1/3}$MnO$_3$ and
La$_{2-x}$Sr$_x$CuO$_4$/La$_{2/3}$Ca$_{1/3}$MnO$_3$ multilayers
cond-mat.str-el cond-mat.mtrl-sci
With x-ray absorption spectroscopy we investigated the orbital reconstruction
and the induced ferromagnetic moment of the interfacial Cu atoms in
YBa$_2$Cu$_3$O$_{7}$/La$_{2/3}$Ca$_{1/3}$MnO$_3$ (YBCO/LCMO) and
La$_{2-x}$Sr$_{x}$CuO$_4$/La$_{2/3}$Ca$_{1/3}$MnO$_3$ (LSCO/LCMO) multilayers.
We demonstrate that these electronic and magnetic proximity effects are coupled
and are common to these cuprate/manganite multilayers. Moreover, we show that
they are closely linked to a specific interface termination with a direct
Cu-O-Mn bond. We furthermore show that the intrinsic hole doping of the cuprate
layers and the local strain due to the lattice mismatch between the cuprate and
manganite layers are not of primary importance. These findings underline the
central role of the covalent bonding at the cuprate/manganite interface in
defining the spin-electronic properties.
| arxiv topic:cond-mat.str-el cond-mat.mtrl-sci |
arxiv_dataset-56961410.8499 | Dynamics and Control of Infections on Social Networks
q-bio.QM q-bio.PE stat.AP
Random mixing in host populations has been a convenient simplifying
assumption in the study of epidemics, but neglects important differences in
contact rates within and between population groups. For HIV/AIDS, the
assumption of random mixing is inappropriate for epidemics that are
concentrated in groups of people at high risk, including female sex workers
(FSW) and their male clients (MCF), injection drug users (IDU) and men who have
sex with men (MSM). To find out who transmits infection to whom and how that
affects the spread and containment of infection remains a major empirical
challenge in the epidemiology of HIV/AIDS. Here we develop a technique, based
on the routine sampling of infection in linked population groups, which shows
how an Asian HIV/AIDS epidemic began in FSW, was propagated mainly by IDU, and
ultimately generated most cases among the female partners of MCF (FPM).
Calculation of the case reproduction numbers within and between groups, and for
the whole network, provides insights into control that cannot be deduced simply
from observations on the prevalence of infection. Specifically, the per capita
rate of HIV transmission was highest from FSW to MCF, and most HIV infections
occurred in FPM, but the number of infections in the whole network is best
reduced by interrupting transmission to and from IDU. This network analysis can
be used to guide HIV/AIDS interventions based on needle exchange, condom
distribution and antiretroviral therapy. The method requires only routine data
and could be applied to infections in other populations.
| arxiv topic:q-bio.QM q-bio.PE stat.AP |
arxiv_dataset-56971410.8599 | Charge Symmetry Breaking in the Nucleon and Parity Violating Elastic
Electron-Proton Scattering
nucl-th hep-ph nucl-ex
The basic facts of charge symmetry breaking (CSB) phenomena are reviewed. The
relevance of CSB to parity-violating electron-proton scattering experiments
that seek to extract strange elastic form factors is discussed.
Experimentalists have stated and written that the current uncertainty in our
knowledge of CSB limits the ability to push further on the strange form
factors. I discuss recent calculations using relativistic chiral perturbation
theory and realistic values of strong coupling constants which show that the
uncertainties due to lack of knowledge of CSB are at least ten times smaller
than present experimental uncertainties. Estimates of CSB effects are made for
the JLab Qweak and Mainz P2 experiments.
| arxiv topic:nucl-th hep-ph nucl-ex |
arxiv_dataset-56981410.8699 | Validation of the Frequency Modulation technique applied to the
pulsating delta Sct - gamma Dor eclipsing binary star KIC 8569819
astro-ph.SR
KIC 8569819 is an eclipsing binary star with an early F primary and G
secondary in a 20.85-d eccentric orbit. The primary is a delta Sct - gamma Dor
star pulsating in both p modes and g modes. Using 4 years of Kepler Mission
photometric data we independently model the light curve using the traditional
technique with the modelling code PHOEBE, and we study the orbital
characteristics using the new frequency modulation (FM) technique. We show that
both methods provide the equivalent orbital period, eccentricity and argument
of periastron, thus illustrating and validating the FM technique. In the
amplitude spectrum of the p-mode pulsations we also discovered an FM signal
compatible with a third body in the system, a low mass M dwarf in an 861-d
orbit around the primary pair. However, the eclipses show no timing variations,
indicating that the FM signal is a consequence of the intrinsic change in
pulsation frequency, thus providing a cautionary tale. Our analysis shows the
potential of the FM technique using {\it Kepler} data, and we discuss the
prospects to detect planets and brown dwarfs in Kepler data for A and F stars
even in the absence of transits and with no spectroscopic radial velocity
curves. This opens the possibility of finding planets orbiting hotter stars
that cannot be found by traditional techniques.
| arxiv topic:astro-ph.SR |
arxiv_dataset-56991410.8799 | Reduction of colored noise in excitable systems to white noise and
dynamic boundary conditions
q-bio.NC cond-mat.stat-mech
A recent study on the effect of colored driving noise on the escape from a
metastable state derives an analytic expression of the transfer function of the
leaky integrate-and-fire neuron model subject to colored noise. Here we present
an alternative derivation of the results, taking into account time-dependent
boundary conditions explicitly. This systematic approach may facilitate future
extensions beyond first order perturbation theory. The analogy of the quantum
harmonic oscillator to the LIF neuron model subject to white noise enables a
derivation of the well known transfer function simpler than the original
approach. We offer a pedagogical presentation including all intermediate steps
of the calculations.
| arxiv topic:q-bio.NC cond-mat.stat-mech |
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