pinecone/core-2020-05-10-deduplication huggingface dataset:
Some Spacetimes with Higher Rank Killing-Stackel Tensors

By applying the lightlike Eisenhart lift to several known examples of
low-dimensional integrable systems admitting integrals of motion of
higher-order in momenta, we obtain four- and higher-dimensional Lorentzian
spacetimes with irreducible higher-rank Killing tensors. Such metrics, we
believe, are first examples of spacetimes admitting higher-rank Killing
tensors. Included in our examples is a four-dimensional supersymmetric pp-wave
spacetime, whose geodesic flow is superintegrable. The Killing tensors satisfy
a non-trivial Poisson-Schouten-Nijenhuis algebra. We discuss the extension to
the quantum regime
Schwarzschild Black Hole Quantum Statistics from Z(2) Orientation
  Degrees of Freedom and its Relations to Ising Droplet Nucleation

Generalizing previous quantum gravity results for Schwarzschild black holes
from 4 to D > 3 space-time dimensions yields an energy spectrum E_n = alpha
n^{(D-3)/(D-2)} E_P, n=1,2,..., alpha = O(1), where E_P is the Planck energy in
that space-time. This spectrum means that the quantized area A_{D-2}(n) of the
D-2 dimensional horizon has universally the form A_{D-2} = n a_{D-2}, where
a_{D-2} is essentially the (D-2)th power of the D-dimensional Planck length.
Assuming that the basic area quantum has a Z(2)-degeneracy according to its two
possible orientation degrees of freedom implies a degeneracy d_n = 2^n for the
n-th level. The energy spectrum with such a degeneracy leads to a quantum
canonical partition function which is the same as the classical grand canonical
partition function of a primitive Ising droplet nucleation model for 1st-order
phase transitions in D-2 spatial dimensions. The analogy to this model suggests
that E_n represents the surface energy of a "droplet" of n horizon quanta.
Exploiting the well-known properties of the so-called critical droplets of that
model immediately leads to the Hawking temperature and the Bekenstein-Hawking
entropy of Schwarzschild black holes. The values of temperature and entropy
appear closely related to the imaginary part of the partition function which
describes metastable statesComment: 29 pages, Latex; version to appear in Annalen der Physik (Leipzig)
  (Refs. added, a few text improvements, no changes of results
Cycle frequency in standard Rock-Paper-Scissors games: Evidence from
  experimental economics

The Rock-Paper-Scissors (RPS) game is a widely used model system in game
theory. Evolutionary game theory predicts the existence of persistent cycles in
the evolutionary trajectories of the RPS game, but experimental evidence has
remained to be rather weak. In this work we performed laboratory experiments on
the RPS game and analyzed the social-state evolutionary trajectories of twelve
populations of N=6 players. We found strong evidence supporting the existence
of persistent cycles. The mean cycling frequency was measured to be $0.029 \pm
0.009$ period per experimental round. Our experimental observations can be
quantitatively explained by a simple non-equilibrium model, namely the
discrete-time logit dynamical process with a noise parameter. Our work
therefore favors the evolutionary game theory over the classical game theory
for describing the dynamical behavior of the RPS game.Comment: 7 Page, 3 figure; Keyword: Rock-Paper-Scissors game; cycle; social
  state; population dynamics; evolutionary trajector
New solutions for the color-flavor locked strangelets

Recent publications rule out the negatively charged beta equilibrium
strangelets in ordinary phase, and the color-flavor locked (CFL) strangelets
are reported to be also positively charged. This letter presents new solutions
to the system equations where CFL strangelets are slightly negatively charged.
If the ratio of the square-root bag constant to the gap parameter is smaller
than 170 MeV, the CFL strangelets are more stable than iron and the normal
unpaired strangelets. For the same parameters, however, the positively charged
CFL strangelets are more stable.Comment: 5 pages, 4 figures, Revtex4 styl
Evidence of several dipolar quasi-invariants in Liquid Crystals

In a closed quantum system of N coupled spins with magnetic quantum number I,
there are about (2I + 1)^N constants of motion. However, the possibility of
observing such quasi-invariant (QI) states in solid-like spin systems in
Nuclear Magnetic Resonance (NMR) is not a strictly exact prediction. The aim of
this work is to provide experimental evidence of several QI, in the proton NMR
of small spin clusters, besides those already known Zeeman, and dipolar orders
(strong and weak). We explore the spin states prepared with the
Jeener-Broekaert pulse sequence by analyzing the time-domain signals yielded by
this sequence as a function of the preparation times, in a variety of dipolar
networks. We observe that the signals can be explained with two dipolar QIs
only within a range of short preparation times. At longer times the time-domain
signals have an echo-like behaviour. We study their multiple quantum coherence
content on a basis orthogonal to the z-basis and see that such states involve a
significant number of correlated spins. Then we show that the whole preparation
time-scale can only be reconstructed by assuming the occurrence of multiple QI
which we isolate experimentally
The XMM-Newton deep survey in the CDF-S VI. Obscured AGN selected as
  infrared power-law galaxies

Accretion onto SMBH is believed to occur mostly in obscured AGN. Such objects
are proving rather elusive in surveys of distant galaxies, including those at
X-ray energies. Our main goal is to determine whether the revised IRAC criteria
of Donley et al. (2012) (objects with an IR power-law spectral shape), are
effective at selecting X-ray type-2 AGN. We present the results from the X-ray
spectral analysis of 147 AGN selected by cross-correlating the highest spectral
quality ultra-deep XMM-Newton and the Spitzer/IRAC catalogues in the CDF-S.
Consequently it is biased towards sources with high S/N X-ray spectra. In order
to measure the amount of intrinsic absorption in these sources, we adopt a
simple X-ray spectral model that includes a power-law modified by intrinsic
absorption and a possible soft X-ray component. We find 21/147 sources to be
heavily absorbed but the uncertainties in their obscuring column densities do
not allow us to confirm their Compton-Thick nature without resorting to
additional criteria. Although IR power-law galaxies are less numerous in our
sample than IR non-power-law galaxies (60 versus 87 respectively), we find that
the fraction of absorbed (N_{H} > 10^{22} cm^{-2}) AGN is significantly higher
(at about 3 sigma level) for IR-power-law sources ($\sim$2/3) than for those
sources that do not meet this IR selection criteria ($\sim$1/2). This behaviour
is particularly notable at low luminosities, but it appears to be present,
although with a marginal significance, at all luminosities. We therefore
conclude that the IR power-law method is efficient in finding X-ray-absorbed
sources. We would then expect that the long-sought dominant population of
absorbed AGN is abundant among IR power-law spectral shape sources not detected
in X-rays.Comment: 13 pages, 6 figures, 5 tables, accepted to A&A (01/07/2013
Polarized Parton Distributions at an Electron-Ion Collider

We study the potential impact of inclusive deep-inelastic scattering data
from a future electron-ion collider (EIC) on longitudinally polarized parton
distribution (PDFs). We perform a PDF determination using the NNPDF
methodology, based on sets of deep-inelastic EIC pseudodata, for different
realistic choices of the electron and proton beam energies. We compare the
results to our current polarized PDF set, NNPDFpol1.0, based on a fit to
fixed-target inclusive DIS data. We show that the uncertainties on the first
moments of the polarized quark singlet and gluon distributions are
substantially reduced in comparison to NNPDFpol1.0, but also that more
measurements may be needed to ultimately pin down the size of the gluon
contribution to the nucleon spin.Comment: 11 pages, 6 figures. Two plots in Fig.5 added and discussion of
  extrapolation uncertainties expanded. Final version, published in Phys. Lett.
Measurement of the triple-differential cross section for photon + jets
  production in proton-proton collisions at sqrt(s) = 7 TeV

A measurement of the triple-differential cross section (sigma as a function
of the photon pt and eta and the jet eta) in photon + jets final states using a
data sample from proton-proton collisions at sqrt(s) = 7 TeV is presented. This
sample corresponds to an integrated luminosity of 2.14 inverse femtobarns
collected by the CMS detector at the LHC. Photons and jets are reconstructed
within a pseudorapidity range of abs(eta) < 2.5, and are required to have
transverse momenta in the range 40 < pt(gamma) < 300 GeV and pt(jet) > 30 GeV,
respectively. The measurements are compared to theoretical predictions from the
SHERPA leading-order QCD Monte Carlo event generator and the
next-to-leading-order perturbative QCD calculation from JETPHOX. The
predictions are found to be consistent with the data over most of the examined
kinematic region.Comment: Replaced with published version. Added journal reference and DO
On deformations of AdS_n x S^n supercosets

We study the deformed AdS_5 x S^5 supercoset model of arXiv:1309.5850 which
depends on one parameter kappa and has classical quantum group symmetry. We
confirm the conjecture that in the "maximal" deformation limit kappa ->
infinity this model is T-dual to "flipped" double Wick rotation of the target
space AdS_5 x S^5, i.e. dS_5 x H^5 space supported by an imaginary 5-form flux.
In the imaginary deformation limit, kappa -> i, the corresponding target space
metric is of a pp-wave type and thus the resulting light-cone gauge S-matrix
becomes relativistically invariant. Omitting non-unitary contributions of
imaginary WZ terms, we find that this tree-level S-matrix is equivalent to that
of the generalized sine-Gordon model representing the Pohlmeyer reduction of
the undeformed AdS_5 x S^5 superstring model. We also study in some detail
similar deformations of the AdS_3 x S^3 and AdS_2 x S^2 supercosets. The
bosonic part of the deformed AdS_3 x S^3 model happens to be equivalent to the
symmetric case of the sum of the Fateev integrable deformation of the SL(2) and
SU(2) principal chiral models, while in the AdS_2 x S^2 case the role of the
Fateev model is played by the 2d "sausage" model. The kappa = i limits are
again directly related to the Pohlmeyer reductions of the corresponding AdS_n x
S^n supercosets: (2,2) super sine-Gordon model and its complex sine-Gordon
analog. We also discuss possible deformations of AdS_3 x S^3 with more than one
parameter.Comment: 31 pages; v2: 33 pages, comments on unitarity and finiteness added
  and misprints corrected; v3: minor change
The degeneracy of M33 mass modelling and its physical implications

The Local Group galaxy M33 exhibits a regular spiral structure and is close
enough to permit high resolution analysis of its kinematics, making it an ideal
candidate for rotation curve studies of its inner regions. Previous studies
have claimed the galaxy has a dark matter halo with an NFW profile, based on
statistical comparisons with a small number of other profiles. We apply a
Bayesian method from our previous paper to place the dark matter density
profile in the context of a continuous, and more general, parameter space. For
a wide range of initial assumptions we find that models with inner log slope
$\gamma_{\rm in}<0.9$ are strongly excluded by the kinematics of the galaxy
unless the mass-to-light ratio of the stellar components in the $3.6\mu$m band
satisfies $\Upsilon_{3.6}\geq2$. Such a high $\Upsilon_{3.6}$ is inconsistent
with current modelling of the stellar population of M33. This suggests that M33
is a galaxy whose dark matter halo has not been significantly modified by
feedback. We discuss possible explanations of this result, including ram
pressure stripping during earlier interactions with M31.Comment: 10 pages, 10 figures. Accepted by Ap
Lifshitz Space-Times for Schroedinger Holography

We show that asymptotically locally Lifshitz space-times are holographically
dual to field theories that exhibit Schroedinger invariance. This involves a
complete identification of the sources, which describe torsional Newton-Cartan
geometry on the boundary and transform under the Schroedinger algebra. We
furthermore identify the dual vevs from which we define and construct the
boundary energy-momentum tensor and mass current and show that these obey Ward
identities that are organized by the Schroedinger algebra. We also point out
that even though the energy flux has scaling dimension larger than z+2, it can
be expressed in terms of computable vev/source pairs.Comment: 16 pages, clarifications added, typos fixed, refs update
Chronological structure of a Goedel type universe with negative
  cosmological constant

We show that the Goedel solution of five-dimensional gauged supergravity
contains either closed time-like curves through every space-time point or none
at all, dependent on the rotational parameter. In addition, we present a
deformation of that solution with a parameter kappa which characterizes the
symmetry of four-dimensional base space: for kappa = 1, 0, -1 it has spherical,
flat and hyperbolic symmetry, respectively. Also investigated are the causal
properties of the lifted solution in 10 dimensions.Comment: 10 pages, LaTeX (v2: added new references
Studies of a sample of 6C radio galaxies at redshift one; 1, Deep multi-frequency radio observations

Deep radio observations at 5 and 8 GHz are presented of a complete sample of 11 radio galaxies with redshifts 0.85 < z < 1.5, selected from the 6C sample of Eales. The radio data, taken using the VLA in A, B and C array configurations, provide a best angular resolution of 0.25'' and reach an rms noise level of order 20 microJy. Radio core candidates are detected in 8 of the 11 sources. 9 of the 11 sources display deviations from `standard double radio source' morphologies, with multiple hotspots or a hotspot withdrawn from the leading edge of the radio emission. The sources are typically polarised at the 5 to 15% level. The mean rotation measures of the individual lobes are less than 50 rad/m^2 but strong asymmetries between the two lobes indicate that the Faraday rotation does not have a Milky Way origin; rather, the distant 6C radio sources lie in a relatively dense clumpy environment. The sources are compared with the more radio powerful distant 3CR radio galaxies and with low redshift sources. The ratio of core to extended radio flux is almost independent of the radio source size and only weakly inversely correlated with the total radio power. This indicates that the high radio luminosity of the most powerful radio sources must originate in the AGN, in contrast to the suggestion that they are so luminous only due to confinement by a dense surrounding environment. Environmental effects play a secondary role. (Abridged
Balanced homodyne detection in second-harmonic generation microscopy

We demonstrate the association of two-photon nonlinear microscopy with
balanced homodyne detection for investigating second harmonic radiation
properties at nanoscale dimensions. Variation of the relative phase between
second-harmonic and fundamental beams is retrieved, as a function of the
absolute orientation of the nonlinear emitters. Sensitivity down to
approximately 3.2 photon/s in the spatio-temporal mode of the local oscillator
is obtained. This value is high enough to efficiently detect the coherent
second-harmonic emission from a single KTiOPO4 crystal of sub-wavelength size.Comment: 9 pages to appear in Applied Physics Letter
Computational modeling of transcranial direct current stimulation (tDCS) in obesity: Impact of head fat and dose guidelines☆

Recent studies show that acute neuromodulation of the prefrontal cortex with transcranial direct current stimulation (tDCS) can decrease food craving, attentional bias to food, and actual food intake. These data suggest potential clinical applications for tDCS in the field of obesity. However, optimal stimulation parameters in obese individuals are uncertain. One fundamental concern is whether a thick, low-conductivity layer of subcutaneous fat around the head can affect current density distribution and require dose adjustments during tDCS administration. The aim of this study was to investigate the role of head fat on the distribution of current during tDCS and evaluate whether dosing standards for tDCS developed for adult individuals in general are adequate for the obese population. We used MRI-derived high-resolution computational models that delineated fat layers in five human heads from subjects with body mass index (BMI) ranging from “normal-lean” to “super-obese” (20.9 to 53.5 kg/m2). Data derived from these simulations suggest that head fat influences tDCS current density across the brain, but its relative contribution is small when other components of head anatomy are added. Current density variability between subjects does not appear to have a direct and/or simple link to BMI. These results indicate that guidelines for the use of tDCS can be extrapolated to obese subjects without sacrificing efficacy and/or treatment safety; the recommended standard parameters can lead to the delivery of adequate current flow to induce neuromodulation of brain activity in the obese population
Comprehensive comparative analysis of RNA sequencing methods for degraded or low input samples

RNA-Seq is an effective method to study the transcriptome, but can be difficult to apply to scarce or degraded RNA from fixed clinical samples, rare cell populations, or cadavers. Recent studies have proposed several methods for RNA-Seq of low quality and/or low quantity samples, but their relative merits have not been systematically analyzed. Here, we compare five such methods using metrics relevant to transcriptome annotation, transcript discovery, and gene expression. Using a single human RNA sample, we constructed and sequenced ten libraries with these methods and two control libraries. We find that the RNase H method performed best for low quality RNA, and confirmed this with actual degraded samples. RNase H can even effectively replace oligo (dT) based methods for standard RNA-Seq. SMART and NuGEN had distinct strengths for low quantity RNA. Our analysis allows biologists to select the most suitable methods and provides a benchmark for future method development
Effects of parameter estimation on prediction densities: a bootstrap approach.

We use abootstrap procedure to study the impact of parameterestimation on predictiondensities, focusing on seasonal ARIMA processes with possibly non normal innovations. We compare predictiondensities obtained using the Box and Jenkins approach with bootstrapdensities which may be constructed either taking into account parameterestimation variability or using parameter estimates as if they were known parameters. By means of Monte Carlo experiments, we show that the average coverage of the intervals is closer to the nominal value when intervals are constructed incorporating parameter uncertainty. The effects of parameterestimation are particularly important for small sample sizes and when the error distribution is not Gaussian. We also analyze the effect of the estimation method on the shape of predictiondensities comparing predictiondensities constructed when the parameters are estimated by Ordinary Least Squares (OLS) and by Least Absolute Deviations (LAD). We show how, when the error distribution is not Gaussian, the average coverage and length of intervals based on LAD estimates are closer to nominal values than those based on OLS estimates. Finally, the performance of the bootstrap intervals is illustrated with two empirical examples.Acknowledgements The authors are very grateful to the referees for comments that helped to improve the paper. Also, we are grateful to Lory A. Thombs for her comments, to Eva Senra for providing the Italian IPI data and to Regina Kaiser for helping us to clean the series of outliers. Financial support was provided by the European Union project ERBCHRXCT 940514 and by projects CICYT PB95-0299, DGICYT PB96-0111 from the Spanish Government and Cátedra de Calidad BBV.Publicad
Transition State Theory for dissipative systems without a dividing
  surface

Transition State Theory is a central cornerstone in reaction dynamics. Its
key step is the identification of a dividing surface that is crossed only once
by all reactive trajectories. This assumption is often badly violated,
especially when the reactive system is coupled to an environment. The
calculations made in this way then overestimate the reaction rate and the
results depend critically on the choice of the dividing surface. In this
Letter, we study the phase space of a stochastically driven system close to an
energetic barrier in order to identify the geometric structure unambiguously
determining the reactive trajectories, which is then incorporated in a simple
rate formula for reactions in condensed phase that is both independent of the
dividing surface and exact.Comment: 4 pages, 3 figure
Rethinking human responses to sea-level rise : the Mesolithic occupation of the Channel Islands

This work provides new insights into human responses to and perceptions of sea-level rise at a time when the landscapes of north-west Europe were radically changing. These issues are investigated through a case study focused on the Channel Islands. We report on the excavation of two sites, Canal du Squez in Jersey and Lihou (GU582) in Guernsey, and the study of museum collections across the Channel Islands. We argue that people were drawn to this area as a result of the dynamic environmental processes occurring and the opportunities these created. The evidence suggests that the area was a particular focus during the Middle Mesolithic, when Guernsey and Alderney were already islands and while Jersey was a peninsula of northern France. Insularisation does not appear to have created a barrier to occupation during either the Middle or Final Mesolithic, indicating the appearance of lifeways increasingly focused on maritime voyaging and marine resources from the second half of the 9th millennium BC onwards.PostprintPeer reviewe