pinecone/core-2020-05-10-deduplication huggingface dataset:
Relationship between imaging biomarkers, age, progression and symptom severity in Alzheimer's disease.

The early diagnostic value of glucose hypometabolism and atrophy as potential neuroimaging biomarkers of mild cognitive impairment (MCI) and Alzheimer's disease (AD) have been extensively explored using [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) and structural magnetic resonance imaging (MRI). The vast majority of previous imaging studies neglected the effects of single factors, such as age, symptom severity or time to conversion in MCI thus limiting generalisability of results across studies. Here, we investigated the impact of these factors on metabolic and structural differences. FDG-PET and MRI data from AD patients (n = 80), MCI converters (n = 65) and MCI non-converters (n = 64) were compared to data of healthy subjects (n = 79). All patient groups were split into subgroups by age, time to conversion (for MCI), or symptom severity and compared to the control group. AD patients showed a strongly age-dependent pattern, with younger patients showing significantly more extensive reductions in gray matter volume and glucose utilisation. In the MCI converter group, the amount of glucose utilisation reduction was linked to the time to conversion but not to atrophy. Our findings indicate that FDG-PET might be more closely linked to future cognitive decline whilst MRI being more closely related to the current cognitive state reflects potentially irreversible damage
Trajectory of neutron$-$neutron$-^{18}C$ excited three-body state

The trajectory of the first excited Efimov state is investigated by using a
renormalized zero-range three-body model for a system with two bound and one
virtual two-body subsystems. The approach is applied to $n-n-^{18}$C, where the
$n-n$ virtual energy and the three-body ground state are kept fixed. It is
shown that such three-body excited state goes from a bound to a virtual state
when the $n-^{18}$C binding energy is increased. Results obtained for the
$n-^{19}$C elastic cross-section at low energies also show dominance of an
$S-$matrix pole corresponding to a bound or virtual Efimov state. It is also
presented a brief discussion of these findings in the context of ultracold atom
physics with tunable scattering lengths
Heterotic twistor-string theory

We reformulate twistor-string theory as a heterotic string based on a twisted
(0,2) model. The path integral localizes on holomorphic maps, while the (0,2)
moduli naturally correspond to the states of N=4 super Yang-Mills and conformal
supergravity under the Penrose transform. We show how the standard
twistor-string formulae of scattering amplitudes as integrals over the space of
curves in supertwistor space may be obtained from our model. The corresponding
string field theory gives rise to a twistor action for N=4 conformal
supergravity coupled to super Yang-Mills. The model helps to explain how the
twistor-strings of Witten and Berkovits are related and clarifies various
aspects of each of these models.Comment: 45 page
PeV scale Left-Right symmetry and baryon asymmetry of the Universe

We study the cosmology of two versions of supersymmetric Left-Right symmetric
model. The scale of the $B-L$ symmetry breaking in these models is naturally
low, $10^4 - 10^6$ GeV. Spontaneous breakdown of parity is accompanied by a
first order phase transition. We simulate the domain walls of the phase
transition and show that they provide requisite conditions, specifically, $CP$
violating phase needed for leptogenesis. Additionally soft resonant
leptogenesis is conditionally viable in the two models considered. Some of the
parameters in the soft supersymmetry breaking terms are shown to be constrained
from these considerations. It is argued that the models may be testable in
upcoming collider and cosmology experiments.Comment: 25 pages, 2 figures, revtex4, minor clarifications, references added,
  conclusion remains same, to appear in Nuclear Physics
MAGIC observation of the GRB 080430 afterglow\ud

Context. Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of gamma-ray bursts during the prompt phase, i.e. the initial burst of high-energy radiation, and during the long-lasting afterglows. In spite of many successes in interpreting these phenomena, there are still several open key questions about the fundamental emission processes, their energetics and the environment. Aims. Independently of specific gamma-ray burst theoretical recipes, spectra in the GeV/TeV range are predicted to be remarkably simple, being satisfactorily modeled with power-laws, and therefore offer a very valuable tool to probe the extragalactic background light distribution. Furthermore, the simple detection of a component at very-high energies, i.e. at similar to 100GeV, would solve the ambiguity about the importance of various possible emission processes, which provide barely distinguishable scenarios at lower energies. Methods. We used the results of the MAGIC telescope observation of the moderate resdhift (z similar to 0.76) GRB 080430 at energies above about 80 GeV, to evaluate the perspective for late-afterglow observations with ground based GeV/TeV telescopes. Results. We obtained an upper limit of F(95% CL) = 5.5 x 10(-11) erg cm(-2) s(-1) for the very-high energy emission of GRB 080430, which cannot set further constraints on the theoretical scenarios proposed for this object also due to the difficulties in modeling the low-energy afterglow. Nonetheless, our observations show that Cherenkov telescopes have already reached the required sensitivity to detect the GeV/TeV emission of GRBs at moderate redshift (z less than or similar to 0.8), provided the observations are carried out at early times, close to the onset of their afterglow phase.\u
Linear maps on k^I, and homomorphic images of infinite direct product
  algebras

Let k be an infinite field, I an infinite set, V a k-vector-space, and
g:k^I\to V a k-linear map. It is shown that if dim_k(V) is not too large (under
various hypotheses on card(k) and card(I), if it is finite, respectively
countable, respectively < card(k)), then ker(g) must contain elements
(u_i)_{i\in I} with all but finitely many components u_i nonzero.
  These results are used to prove that any homomorphism from a direct product
\prod_I A_i of not-necessarily-associative algebras A_i onto an algebra B,
where dim_k(B) is not too large (in the same senses) must factor through the
projection of \prod_I A_i onto the product of finitely many of the A_i, modulo
a map into the subalgebra \{b\in B | bB=Bb=\{0\}\}\subseteq B.
  Detailed consequences are noted in the case where the A_i are Lie algebras.Comment: 14 pages. Lemma 6 has been strengthened, with resulting strengthening
  of other results. Some typos etc. have been correcte
Searching for dark matter in X-rays: how not to check the dark matter
  origin of a spectral feature

In a recent preprint entitled "Searching for dark matter in X-rays: how to
check the dark matter origin of a spectral feature" [arXiv:1001.0644v1], the
authors have claimed that some archival X-ray data could be used to rule out
dark matter in the form of 5-keV sterile neutrinos at the level of 20 sigma.
Unfortunately, the limit was derived incorrectly. We point out the shortcomings
of this analysis and show that the tentative detection of a spectral feature
consistent with a 5-keV sterile neutrino is not in contradiction with existing
limits. Future observations of dwarf spheroidal galaxies will test this
hypothesis.Comment: 5 pages; response to arXiv:1001.0644v
Kochen-Specker theorem studied with neutron interferometer

The Kochen-Specker theorem theoretically shows evidence of the
incompatibility of noncontextual hidden variable theories with quantum
mechanics. Quantum contextuality is a more general concept than quantum
non-locality which is quite well tested in experiments by using Bell
inequalities. Within neutron interferometry we performed an experimental test
of the Kochen-Specker theorem with an inequality, which identifies quantum
contextuality, by using spin-path entanglement in a single neutron system. Here
entanglement is achieved not between different particles, but between degrees
of freedom, i.e., between spin and path degree of freedom. Appropriate
combinations of the spin analysis and the position of the phase shifter allow
an experimental verification of the violation of an inequality of the
Kochen-Specker theorem. The observed value of (2.291 +/- 0.008), which is above
the threshold of 1, clearly shows that quantum mechanical predictions cannot be
reproduced by noncontextual hidden variable theories.Comment: 5 pages, 3 figure
The mass-loss return from evolved stars to the Large Magellanic Cloud
  III. Dust properties for carbon-rich asymptotic giant branch stars

We present a 2Dust model for the dust shell around a LMC long-period variable
(LPV) previously studied as part of the OGLE survey. OGLE LMC LPV 28579 (SAGE
J051306.40-690946.3) is a carbon-rich asymptotic giant branch (AGB) star for
which we have photometry and spectra from the Spitzer SAGE and SAGE-Spec
programs along with UBVIJHK_s photometry. By modeling this source, we obtain a
baseline set of dust properties to be used in the construction of a grid of
models for carbon stars. We reproduce its spectral energy distribution using a
mixture of AmC and SiC (15% by mass). The grain sizes are distributed according
to the KMH model. The best-fit model has an optical depth of 0.28 for the shell
at the peak of the SiC feature, with R_in~1430 R_sun or 4.4 R_star. The
temperature at this inner radius is 1310 K. Assuming an expansion velocity of
10 km s^-1, we obtain a dust mass-loss rate of 2.5x10^-9 M_sun yr-1. We
calculate a 15% variation in this rate by testing the fit sensitivity against
variation in input parameters. We also present a simple model for the molecular
gas in the extended atmosphere that could give rise to the 13.7 \mu m feature
seen in the spectrum. We find that a combination of CO and C_2H_2 gas at an
excitation temperature of about 1000 K and column densities of 3x10^21 cm^-2
and 10^19 cm^-2 respectively are able to reproduce the observations. Given that
the excitation temperature is close to T_dust(R_in), most of the molecular
contribution probably arises from the inner shell region. The luminosity
corresponding to the first epoch of SAGE observations is 6580 L_sun. For an
effective temperature of about 3000 K, this implies a stellar mass of 1.5-2
M_sun and an age of 1-2.5 Gyr. For a gas:dust ratio of 200, we obtain a gas
mass-loss rate of 5.0x10^-7 M_sun yr^-1, consistent with the gas mass-loss
rates estimated from the period, color and 8 \mu m flux of the source.Comment: 14 pages, 5 figures, accepted for publication in Astronomy &
  Astrophysic
SDSS J162520.29+120308.7 - a new SU UMa star in the period gap

We report results of an extensive world-wide observing campaign devoted to
the recently discovered dwarf nova SDSS J162520.29+120308.7 (SDSS J1625). The
data were obtained during the July 2010 eruption of the star and in August and
September 2010 when the object was in quiescence. During the July 2010
superoutburst SDSS J1625 clearly displayed superhumps with a mean period of
$P_{\rm sh}=0.095942(17)$ days ($138.16 \pm 0.02$ min) and a maximum amplitude
reaching almost 0.4 mag. The superhump period was not stable, decreasing very
rapidly at a rate of $\dot P = -1.63(14)\cdot 10^{-3}$ at the beginning of the
superoutburst and increasing at a rate of $\dot P = 2.81(20)\cdot 10^{-4}$ in
the middle phase. At the end of the superoutburst it stabilized around the
value of $P_{\rm sh}=0.09531(5)$ day. During the first twelve hours of the
superoutburst a low-amplitude double wave modulation was observed whose
properties are almost identical to early superhumps observed in WZ Sge stars.
The period of early superhumps, the period of modulations observed temporarily
in quiescence and the period derived from radial velocity variations are the
same within measurement errors, allowing us to estimate the most probable
orbital period of the binary to be $P_{\rm orb}=0.09111(15)$ days ($131.20 \pm
0.22$ min). This value clearly indicates that SDSS J1625 is another dwarf nova
in the period gap. Knowledge of the orbital and superhump periods allows us to
estimate the mass ratio of the system to be $q\approx 0.25$. This high value
poses serious problems both for the thermal and tidal instability (TTI) model
describing the behaviour of dwarf novae and for some models explaining the
origin of early superhumps.Comment: 10 pages, 13 figures, accepted for publication in A&
Jet Flavour Identification at the CLIC Multi-TeV e+e- Collider

Jet flavour identification in multi-TeV e+e- collisions is expected to
provide insights on new phenomena at scales beyond those probed by the LHC. The
anticipated high track density and jet collimation represent a new challenge to
jet tagging algorithms. A method, based on the sampling of the jet charged
multiplicity, sensitive to the long decay length and large decay multiplicity
of heavy flavour hadrons is proposed and the expected performances for the
tagging of e+e- -> bb events at 3 TeV are discussed.Comment: 4 pages, 2 figures, to appear in the proceedings of the 5th Int.
  Linear Colliders Workshop - LCWS2000, Fermilab, October 200
Vector Meson Mass Corrections at O(a^2) in PQChPT with Wilson and
  Ginsparg-Wilson quarks

We derive the mixed as well as unmixed lattice heavy meson chiral Lagrangian
up to order O(a^2), with Wilson and Ginsparg-Wilson fermions. We consider two
flavor partially quenched QCD and calculate vector meson mass corrections up to
order O(a^2), including the corrections associated with the violation of
rotational O(4) symmetry down to the hypercubic group. Our calculations also
include the one-loop, phenomenological contribution from the \rho -> \pi\pi
decay channel. The final result is a chiral-continuum extrapolation formula
with model dependent coefficients from which one can recover the physical \rho
meson mass from the large amount of current lattice data. As a verification of
our result, the chiral-continuum extrapolation formula is compared with that
used in numerical simulations.Comment: 11 pages, REVTeX, minor revision in tex
Validity Of The Vafa-Witten Proof On Absence Of Spontaneous Parity
  Breaking In QCD

The vacuum energy response of a quantum field theory is studied as a function
of complex external fields coupled to the symmetry-breaking observables of the
theory. It is found that the energy density is insensitive to spontaneous
symmetry breaking effects along a special direction in the complex plane. In
particular, in the case of vector-like gauge theories such as QCD, the change
in energy generated by coupling to pure-gluonic parity-odd operators is always
a growing function of the external fields along the real axis, independent of
the mode in which symmetry is realized. In light of this, although there is
little doubt that parity is not spontaneously broken in massive QCD, the
validity of the Vafa and Witten proof is, however, questionable.Comment: conclusions are more carefully worded, 5 pages, Revtex4, no figur
Strangeness-changing scalar form factors

We derive expressions for strangeness-changing scalar form factors, which
incorporate known theoretical constraints both at low and high energies. Their
leading behaviour in the limit of a large number of colours is calculated from
the resonance chiral Lagrangian. A set of short-distance constraints on the
scalar resonance couplings is obtained, imposing the form factors to vanish at
infinite momentum transfer. Making use of previous results on S-wave KPi
scattering [1], and a coupled--channel dispersion-relation analysis, the KPi,
KEta and KEta' scalar form factors are calculated up to 2 GeV. These scalar
form factors are a key ingredient in the determination of the corresponding
scalar spectral function which is important in the extraction of the mass of
the strange quark from QCD sum rules as well as hadronic tau decays.Comment: 40 pages, 10 figures, 2 table
Renormalization of the Cabibbo-Kobayashi-Maskawa Matrix in Standard
  Model

We have investigated the present renormalization prescriptions of
Cabibbo-Kobayashi-Maskawa (CKM) matrix, and found there is still not an
integrated prescription to all loop levels. In this paper We propose a new
prescription which is designed for all loop levels in the present perturbative
theory. This new prescription will keep the unitarity of the bare CKM matrix
and make the amplitude of an arbitrary physical process involving quark mixing
convergent and gauge independent.Comment: 4 pages, has been revise
Analyzing and Modeling the Performance of the HemeLB Lattice-Boltzmann
  Simulation Environment

We investigate the performance of the HemeLB lattice-Boltzmann simulator for
cerebrovascular blood flow, aimed at providing timely and clinically relevant
assistance to neurosurgeons. HemeLB is optimised for sparse geometries,
supports interactive use, and scales well to 32,768 cores for problems with ~81
million lattice sites. We obtain a maximum performance of 29.5 billion site
updates per second, with only an 11% slowdown for highly sparse problems (5%
fluid fraction). We present steering and visualisation performance measurements
and provide a model which allows users to predict the performance, thereby
determining how to run simulations with maximum accuracy within time
constraints.Comment: Accepted by the Journal of Computational Science. 33 pages, 16
  figures, 7 table
Enhanced J/Psi-pair production from double parton scatterings in
  nucleus-nucleus collisions at the Large Hadron Collider

A generic expression of double-parton scattering cross sections in
high-energy nucleus-nucleus (A-A) collisions is derived as a function of the
corresponding single-parton hard cross sections and of the A-A event
centrality. We consider the case of prompt-J/psi production in lead-lead
(Pb-Pb) at the CERN Large Hadron Collider and find that about 20% (35%) of the
J/psi events in minimum-bias (most central) collisions contain a second J/psi
from double parton interactions. In Pb-Pb at 5.5 TeV, in the absence of
final-state effects, about 240 double-J/psi events are expected per unit
midrapidity and per inverse-nanobarn in the dilepton decay modes. The
implications of double-J/psi production on the interpretation of the observed
J/psi suppression in A-A collisions are discussed.Comment: 7 pages, 3 figures, 1 tabl
Nonzero |U_e3| from Charged Lepton Corrections and the Atmospheric
  Neutrino Mixing Angle

After the successful determination of the reactor neutrino mixing angle
\theta_13 ~ 0.16 \neq 0, a new feature suggested by the current neutrino
oscillation data is a sizeable deviation of the atmospheric neutrino mixing
angle \theta_23 from \pi/4. Using the fact that the neutrino mixing matrix U =
U_e^\dagger U_\nu, where U_e and U_\nu result from the diagonalisation of the
charged lepton and neutrino mass matrices, and assuming that U_\nu has a i)
bimaximal (BM), ii) tri-bimaximal (TBM) form, or else iii) corresponds to the
conservation of the lepton charge L' = L_e - L_\mu - L_\tau (LC), we
investigate quantitatively what are the minimal forms of U_e, in terms of
angles and phases it contains, that can provide the requisite corrections to
U_\nu so that \theta_13, \theta_23 and the solar neutrino mixing angle
\theta_12 have values compatible with the current data. Two possible orderings
of the 12 and the 23 rotations in U_e, "standard" and "inverse", are
considered. The results we obtain depend strongly on the type of ordering. In
the case of "standard" ordering, in particular, the Dirac CP violation phase
\delta, present in U, is predicted to have a value in a narrow interval around
i) \delta ~ \pi in the BM (or LC) case, ii) \delta ~ 3\pi/2 or \pi/2 in the TBM
case, the CP conserving values \delta = 0, \pi, 2\pi being excluded in the TBM
case at more than 4\sigma. In the addendum we discuss the implications of the
latest 2013 data.Comment: 35 pages, 10 figures. Version 3: addendum with an update of the
  results based on global analyses including the 2013 data (pages 31-35
The KeV Majoron as Dark Matter Particle

We consider a very weakly interacting KeV majoron as dark matter particle
(DMP), which provides both the critical density $\rho_{cr} = 1.88 \times
10^{-29} h^{2}$ $g/cm^{3}$ and the galactic scale $M_{gal}$ $\sim
m^{3}_{Pl}/m^{2}_{J} \sim 10^{12} M_{\odot} (m_{J}/1 KeV)^{-2}$ for galaxy
formation. The majoron couples to leptons only through some new "directly
interacting particles", called DIPS, and this provides the required smallness
of the coupling constants. If the masses of these DIPS are greater than the
scale $V_s$ characterizing the spontaneous violation of the global lepton
symmetry they are absent at the corresponding phase transition ($T \sim V_s$)
and the majorons are produced during the phase transition, never being in
thermal equilibrium during the history of the universe. In the alternative case
$m_{DIP} < V_{s}$ the majorons can be for a short period in thermal
equilibrium. This scenario is not forbidden by nucleosynthesis and gives a
reasonable growth factor for the density fluctuations compatible with COBE. A
possible signature is an X-ray line at $E_\gamma = \frac{m_J}{2}$, produced by
the decay $J \to \gamma + \gamma$. A model is described which realizes the
possibility of the KeV majoron as DMP and may also lead to observable rates for
decays such as $\mu \ra e \gamma$ and $\mu \ra 3e$.Comment: 13 pages, 3 figures available upon request, FTUV/93-35, late
Herschel/PACS Survey of protoplanetary disks in Taurus/Auriga --
  Observations of [OI] and [CII], and far infrared continuum

The Herschel Space Observatory was used to observe ~ 120 pre-main-sequence
stars in Taurus as part of the GASPS Open Time Key project. PACS was used to
measure the continuum as well as several gas tracers such as [OI] 63 \mu m,
[OI] 145 \mu m, [CII] 158 \mu m, OH, H2O and CO. The strongest line seen is
[OI] at 63 \mu m. We find a clear correlation between the strength of the [OI]
63 \mu m line and the 63 \mu m continuum for disk sources. In outflow sources,
the line emission can be up to 20 times stronger than in disk sources,
suggesting that the line emission is dominated by the outflow. The tight
correlation seen for disk sources suggests that the emission arises from the
inner disk ($<$ 50 AU) and lower surface layers of the disk where the gas and
dust are coupled. The [OI] 63 \mu m is fainter in transitional stars than in
normal Class II disks. Simple SED models indicate that the dust responsible for
the continuum emission is colder in these disks, leading to weaker line
emission. [CII] 158 \mu m emission is only detected in strong outflow sources.
The observed line ratios of [OI] 63 \mu m to [OI] 145 \mu m are in the regime
where we are insensitive to the gas-to-dust ratio, neither can we discriminate
between shock or PDR emission. We detect no Class III object in [OI] 63 \mu m
and only three in continuum, at least one of which is a candidate debris disk.Comment: 84 pages, 14 figures, 5 tables. Accepted by Ap
$U(1)_{B-L}$ extra-natural inflation with Standard Model on a brane

The interrelation between inflationary cosmology and new physics beyond the
Standard Model (SM) is studied in a $U(1)_{B-L}$ extension of the SM embedded
in a (4+1)-dimensional spacetime. In the scenario we study, the inflaton arises
from the Wilson loop of the $U(1)_{B-L}$ gauge group winding an
extra-dimensional cycle. Particular attention is paid to the coupling between
the inflaton and SM particles that are confined on a brane localised in the
extra dimension. We find that the inflaton decay channels are rather restricted
in this scenario and the resulting reheating temperature is relatively low.Comment: 1+14 page