pinecone/core-2020-05-10-deduplication huggingface dataset:
Formation of S0 galaxies through mergers. V. Antitruncated stellar discs
  resulting from major mergers

Lenticular galaxies (S0s) are more likely to host antitruncated (Type-III)
stellar discs than galaxies of later Hubble types. Major mergers are popularly
considered too violent mechanisms to form these breaks. We have investigated
whether major mergers can result into S0-like remnants with realistic
antitruncated stellar discs or not. We have analysed 67 relaxed S0 and E/S0
remnants resulting from dissipative N-body simulations of major mergers from
the GalMer database. We have simulated realistic R-band surface brightness
profiles of the remnants to identify those with antitruncated stellar discs.
Their inner and outer discs and the breaks are quantitatively characterized to
compare with real data. Nearly 70% of our S0-like remnants are antitruncated,
meaning that major mergers that result in S0s have a high probability of
producing Type-III stellar discs. Our remnants lie on top of the extrapolations
of the observational trends (towards brighter magnitudes and higher break
radii) in several photometric diagrams. In scale-free photometric diagrams,
simulations and observations overlap and the remnants reproduce the
observational trends, so the physical mechanism after antitruncations is highly
scalable. We have found novel photometric scaling relations between the
characteristic parameters of the antitruncations in real S0s, which are also
reproduced by our simulations. The trends in all the photometric planes can be
derived from three basic scaling relations that real and simulated Type-III S0s
fulfill: h_i \prop R_brkIII, h_o \prop R_brkIII, and mu_brkIII \prop R_brkIII,
where h_i and h_o are the scalelenghts of the inner and outer discs, and
mu_brkIII and R_brkIII are the surface brightness and radius of the breaks.
Mayor mergers provide a feasible mechanism to form realistic antitruncated S0
galaxies (abridged).Comment: Published in Astronomy & Astrophysics. 31 pages, 17 figures. Language
  corrections by the journal included in this new version. Title change
Detecting the Upturn of the Solar $^8$B Neutrino Spectrum with LENA

LENA (Low Energy Neutrino Astronomy) has been proposed as a next generation
50 kt liquid scintillator detector. The large target mass allows a high
precision measurement of the solar $^8$B neutrino spectrum, with an
unprecedented energy threshold of 2 MeV. Hence, it can probe the MSW-LMA
prediction for the electron neutrino survival probability in the transition
region between vacuum and matter-dominated neutrino oscillations. Based on
Monte Carlo simulations of the solar neutrino and the corresponding background
spectra, it was found that the predicted upturn of the solar $^8$B neutrino
spectrum can be detected with 5 sigma significance after 5 y
The Heisenberg Matrix Formulation of Quantum Field Theory

Heisenberg's matrix formulation of quantum mechanics can be generalized to
relativistic systems by evolving in light-front time tau = t+z/c. The spectrum
and wavefunctions of bound states, such as hadrons in quantum chromodynamics,
can be obtained from matrix diagonalization of the light-front Hamiltonian on a
finite dimensional light-front Fock basis defined using periodic boundary
conditions in the light-front space coordinates. This method, discretized
light-cone quantization (DLCQ), preserves the frame-independence of the front
form even at finite resolution and particle number. Light-front quantization
can also be used in the Hamiltonian form to construct an event generator for
high energy physics reactions at the amplitude level. The light-front partition
function, summed over exponentially-weighted light-front energies, has simple
boost properties which may be useful for studies in heavy ion collisions. I
also review recent work which shows that the structure functions measured in
deep inelastic lepton scattering are affected by final-state rescattering, thus
modifying their connection to light-front probability distributions. In
particular, the shadowing of nuclear structure functions is due to destructive
interference effects from leading-twist diffraction of the virtual photon,
physics not included in the nuclear light-front wavefunctions.Comment: Invited talk presented at the Symposium on the Centennial of Werner
  Heisenberg: Works And Impact, Bamberg, Germany, 26-30 September 200
The gauge invariance of the non-Abelian Chern-Simons action for D-branes
  revisited

We present an elegant method to prove the invariance of the Chern-Simons part
of the non-Abelian action for N coinciding D-branes under the R-R and NS-NS
gauge transformations, by carefully defining what is meant by a background
gauge transformation in the non-Abelian world volume action. We study as well
the invariance under massive gauge transformations of the massive Type IIA
supergravity and show that no massive dielectric couplings are necessary to
achieve this invariance. We show that this result is consistent with (massive)
T-duality from the non-Abelian action for N D9-branes.Comment: Latex, 11 pages. v2: reference added. v3: minor changes and typos
  corrected. version to appear in Phys. Lett.
Enhanced Gauge Symmetry in Type II and F-Theory Compactifications:
  Dynkin Diagrams from Polyhedra

We explain the observation by Candelas and Font that the Dynkin diagrams of
nonabelian gauge groups occurring in type IIA and F-theory can be read off from
the polyhedron $\Delta^*$ that provides the toric description of the Calabi-Yau
manifold used for compacification. We show how the intersection pattern of
toric divisors corresponding to the degeneration of elliptic fibers follows the
ADE classification of singularities and the Kodaira classification of
degenerations. We treat in detail the cases of elliptic K3 surfaces and K3
fibered threefolds where the fiber is again elliptic. We also explain how even
the occurrence of monodromy and non-simply laced groups in the latter case is
visible in the toric picture. These methods also work in the fourfold case.Comment: 26 pages, LaTeX2e, 17 figures, references adde
Non-commutative Pieri operators on posets

We consider graded representations of the algebra NC of noncommutative
symmetric functions on the Z-linear span of a graded poset P. The matrix
coefficients of such a representation give a Hopf morphism from a Hopf algebra
HP generated by the intervals of P to the Hopf algebra of quasi-symmetric
functions. This provides a unified construction of quasi-symmetric generating
functions from different branches of algebraic combinatorics, and this
construction is useful for transferring techniques and ideas between these
branches. In particular we show that the (Hopf) algebra of Billera and Liu
related to Eulerian posets is dual to the peak (Hopf) algebra of Stembridge
related to enriched P-partitions, and connect this to the combinatorics of the
Schubert calculus for isotropic flag manifolds.Comment: LaTeX 2e, 22 pages Minor corrections, updated references. Complete
  and final version, to appear in issue of J. Combin. Th. Ser. A dedicated to
  G.-C. Rot
High pt Measurements at the CERN SPS

The current experimental situation concerning high pt observables at the CERN
SPS is reviewed. Recent data from the NA45, NA49 and NA57 collaborations are
discussed and compared to earlier measurements by WA98 and NA45 at the same
center-of-mass energies, as well as to measurements at the higher energies by
the RHIC experiments. The observables include new p+p, A+A spectra, nuclear
modification factors (R_AA, R_CP), two particle azimuthal correlations, and
baryon to meson ratios at moderately high pt. Generally, the interpretation of
the SPS data suffers from the lack of reliable baseline measurements (p+p and
p+A). However, the overall picture that is emerging suggests that already at
SPS energies medium effects similar to those observed at RHIC are present.Comment: Invited plenary talk at the Hard Probes Conference Asilomar, CA, June
  9-16, 2006, to be published in Nucl. Phys.
Coherent two pion photoproduction on 12C

We develop the formalism for coherent two pion photoproduction in nuclei and
perform actual calculations of cross sections for $\pi^-\pi^+$ and $\pi^0\pi^0$
photoproduction on $^{12}C$. We find that due to the isospin symmetry the cross
section for $\pi^0\pi^0$ production is very small and has a maximum when the
pions propagate together. However, the kinematical region where the energies
and polar angles of the two $\pi^0$ mesons are equal and their relative
azimuthal angle $\phi=180^0$ is forbidden. Conversely in the $\pi^-\pi^+$
production the pions prefer to have a relative azimuthal angle 180$^0$ and the
production of the pions propagating together is suppressed. The dominant
one-body mechanism in both channels is related to the excitation of the
$\Delta$ isobar. Hence the reaction can serve as a source of information about
$\Delta$'s properties in nucleus. We have found that the reaction is sensitive
to effects of the pion and $\Delta$ renormalization in the nuclear medium,
similar to those found in the coherent $(\gamma,\pi^0)$ reaction, but magnified
because of the presence of the two pions.Comment: 17 pages LATEX and 11 postscript figure
Kv2 dysfunction after peripheral axotomy enhances sensory neuron responsiveness to sustained input.

This article is available on the publishers website via Open AccessPeripheral nerve injuries caused by trauma are associated with increased sensory \ud
      neuron excitability and debilitating chronic pain symptoms. Axotomy-induced\ud
      alterations in the function of ion channels are thought to largely underlie the\ud
      pathophysiology of these phenotypes. Here, we characterise the mRNA distribution \ud
      of Kv2 family members in rat dorsal root ganglia (DRG) and describe a link\ud
      between Kv2 function and modulation of sensory neuron excitability. Kv2.1 and\ud
      Kv2.2 were amply expressed in cells of all sizes, being particularly abundant in \ud
      medium-large neurons also immunoreactive for neurofilament-200. Peripheral\ud
      axotomy led to a rapid, robust and long-lasting transcriptional Kv2\ud
      downregulation in the DRG, correlated with the onset of mechanical and thermal\ud
      hypersensitivity. The consequences of Kv2 loss-of-function were subsequently\ud
      investigated in myelinated neurons using intracellular recordings on ex vivo DRG \ud
      preparations. In naive neurons, pharmacological Kv2.1/Kv2.2 inhibition by\ud
      stromatoxin-1 (ScTx) resulted in shortening of action potential (AP)\ud
      after-hyperpolarization (AHP). In contrast, ScTx application on axotomized\ud
      neurons did not alter AHP duration, consistent with the injury-induced Kv2\ud
      downregulation. In accordance with a shortened AHP, ScTx treatment also reduced\ud
      the refractory period and improved AP conduction to the cell soma during high\ud
      frequency stimulation. These results suggest that Kv2 downregulation following\ud
      traumatic nerve lesion facilitates greater fidelity of repetitive firing during\ud
      prolonged input and thus normal Kv2 function is postulated to limit neuronal\ud
      excitability. In summary, we have profiled Kv2 expression in sensory neurons and \ud
      provide evidence for the contribution of Kv2 dysfunction in the generation of\ud
      hyperexcitable phenotypes encountered in chronic pain states
Evidence for Dark Matter Self-Interactions via Collisionless Shocks in
  Cluster Mergers

While dark matter self-interactions may solve several problems with structure
formation, so far only the effects of two-body scatterings of dark matter
particles have been considered. We show that, if a subdominant component of
dark matter is charged under an unbroken $U(1)$ gauge group, collective dark
plasma effects need to be taken into account to understand its dynamics. Plasma
instabilities can lead to collisionless dark matter shocks in galaxy cluster
mergers which might have been already observed in the Abell 3827 and 520
clusters. As a concrete model we propose a thermally produced dark pair plasma
of vectorlike fermions. In this scenario the interacting dark matter component
is expected to be separated from the stars and the non-interacting dark matter
halos in cluster collisions. In addition, the missing satellite problem is
softened, while constraints from all other astrophysical and cosmological
observations are avoided.Comment: Matches the version to be published in Physics Letters
Universal features of Lifshitz Green's functions from holography

We examine the behavior of the retarded Green's function in theories with
Lifshitz scaling symmetry, both through dual gravitational models and a direct
field theory approach. In contrast with the case of a relativistic CFT, where
the Green's function is fixed (up to normalization) by symmetry, the generic
Lifshitz Green's function can a priori depend on an arbitrary function
$\mathcal G(\hat\omega)$, where $\hat\omega=\omega/|\vec k|^z$ is the
scale-invariant ratio of frequency to wavenumber, with dynamical exponent $z$.
Nevertheless, we demonstrate that the imaginary part of the retarded Green's
function (i.e. the spectral function) of scalar operators is exponentially
suppressed in a window of frequencies near zero. This behavior is universal in
all Lifshitz theories without additional constraining symmetries. On the
gravity side, this result is robust against higher derivative corrections,
while on the field theory side we present two $z=2$ examples where the
exponential suppression arises from summing the perturbative expansion to
infinite order.Comment: 32 pages, 4 figures, v2: reference added, v3: fixed bug in
  bibliograph
Two Particle-in-Grid Realisations on Spacetrees

The present paper studies two particle management strategies for dynamically
adaptive Cartesian grids at hands of a particle-in-cell code. One holds the
particles within the grid cells, the other within the grid vertices. The
fundamental challenge for the algorithmic strategies results from the fact that
particles may run through the grid without velocity constraints. To facilitate
this, we rely on multiscale grid representations. They allow us to lift and
drop particles between different spatial resolutions. We call this cell-based
strategy particle in tree (PIT). Our second approach assigns particles to
vertices describing a dual grid (PIDT) and augments the lifts and drops with
multiscale linked cells.
  Our experiments validate the two schemes at hands of an electrostatic
particle-in-cell code by retrieving the dispersion relation of Langmuir waves
in a thermal plasma. They reveal that different particle and grid
characteristics favour different realisations. The possibility that particles
can tunnel through an arbitrary number of grid cells implies that most data is
exchanged between neighbouring ranks, while very few data is transferred
non-locally. This constraints the scalability as the code potentially has to
realise global communication. We show that the merger of an analysed tree
grammar with PIDT allows us to predict particle movements among several levels
and to skip parts of this global communication a priori. It is capable to
outperform several established implementations based upon trees and/or
space-filling curves
Design Strategies for Self-Assembly of Discrete Targets

Both biological and artificial self-assembly processes can take place by a
range of different schemes, from the successive addition of identical building
blocks, to hierarchical sequences of intermediates, all the way to the fully
addressable limit in which each component is unique. In this paper we introduce
an idealized model of cubic particles with patterned faces that allows
self-assembly strategies to be compared and tested. We consider a simple
octameric target, starting with the minimal requirements for successful
self-assembly and comparing the benefits and limitations of more sophisticated
hierarchical and addressable schemes. Simulations are performed using a hybrid
dynamical Monte Carlo protocol that allows self-assembling clusters to
rearrange internally while still providing Stokes-Einstein-like diffusion of
aggregates of different sizes. Our simulations explicitly capture the
thermodynamic, dynamic and steric challenges typically faced by self-assembly
processes, including competition between multiple partially-completed
structures. Self-assembly pathways are extracted from the simulation
trajectories by a fully extendable scheme for identifying structural fragments,
which are then assembled into history diagrams for successfully completed
target structures. For the simple target, a one-component assembly scheme is
most efficient and robust overall, but hierarchical and addressable strategies
can have an advantage under some conditions if high yield is a priority.Comment: 15 pages, 15 figure
Effect of stress level on the high temperature deformation and fracture mechanisms of Ti-45Al-2Nb-2Mn-0.8 vol. pct TiB²: an 'In Situ' experimental study

The effect of the applied stress on the deformation and crack nucleation and propagation mechanisms of a gamma-TiAl intermetallic alloy (Ti-45Al-2Nb-2Mn (at. pct)-0.8 vol. pct TiB2) was examined by means of in situ tensile (constant strain rate) and tensile-creep (constant load) experiments performed at 973 K (700 °C) using a scanning electron microscope. Colony boundary cracking developed during the secondary stage in creep tests at 300 and 400 MPa and during the tertiary stage of the creep tests performed at higher stresses. Colony boundary cracking was also observed in the constant strain rate tensile test. Interlamellar ledges were only found during the tensile-creep tests at high stresses (sigma > 400 MPa) and during the constant strain rate tensile test. Quantitative measurements of the nature of the crack propagation path along secondary cracks and along the primary crack indicated that colony boundaries were preferential sites for crack propagation under all the conditions investigated. The frequency of interlamellar cracking increased with stress, but this fracture mechanism was always of secondary importance. Translamellar cracking was only observed along the primary crack.Funding from the Spanish Ministry of Science and Innovation through projects (MAT2009-14547-C02-01 and MAT2009-14547-C02-02) is acknowledged. The Madrid Regional Government partially supported this project through the ESTRUMAT grant (P2009/MAT-1585). CJB acknowledges the support from the Spanish Ministry of Education for his sabbatical stay in Madrid (SAB2009-0045).Publicad
The M31 pixel lensing plan campaign : macho lensing and self-lensing signals

A.G. was supported by NSF grant AST-1103471. M.D. is thankful to Qatar National Research Fund (QNRF), member of Qatar Foundation, for support by grant NPRP 09-476-1-078. P.J. acknowledges support by the Swiss National Science Foundation.We present the final analysis of the observational campaign carried out by the PLAN (Pixel Lensing Andromeda) collaboration to detect a dark matter signal in form of MACHOs through the microlensing effect. The campaign consists of about 1 month/year observations carried out over 4 years (2007-2010) at the 1.5 m Cassini telescope in Loiano (Astronomical Observatory of BOLOGNA, OAB) plus 10 days of data taken in 2010 at the 2 m Himalayan Chandra Telescope monitoring the central part of M31 (two fields of about 13′ × 12.′6). We establish a fully automated pipeline for the search and the characterization of microlensing flux variations. As a result, we detect three microlensing candidates. We evaluate the expected signal through a full Monte Carlo simulation of the experiment completed by an analysis of the detection efficiency of our pipeline. We consider both "self lensing" and "MACHO lensing" lens populations, given by M31 stars and dark matter halo MACHOs, in M31 and the Milky Way, respectively. The total number of events is consistent with the expected self-lensing rate. Specifically, we evaluate an expected signal of about two self-lensing events. As for MACHO lensing, for full 0.5(10-2) M☉ MACHO halos, our prediction is for about four (seven) events. The comparatively small number of expected MACHO versus self-lensing events, together with the small number statistics at our disposal, do not enable us to put strong constraints on that population. Rather, the hypothesis, suggested by a previous analysis, on the MACHO nature of OAB-07-N2, one of the microlensing candidates, translates into a sizeable lower limit for the halo mass fraction in form of the would-be MACHO population, f, of about 15% for 0.5 M☉ MACHOs.Publisher PDFPeer reviewe
Congenital prosopagnosia: multistage anatomical and functional deficits in face processing circuitry

Face recognition is a primary social skill which
depends on a distributed neural network. A pronounced
face recognition deficit in the absence of any lesion is seen
in congenital prosopagnosia. This study investigating 24
congenital prosopagnosic subjects and 25 control subjects
aims at elucidating its neural basis with fMRI and voxelbased
morphometry. We found a comprehensive behavioral
pattern, an impairment in visual recognition for faces
and buildings that spared long-term memory for faces with
negative valence. Anatomical analysis revealed diminished
gray matter density in the bilateral lingual gyrus, the right
middle temporal gyrus, and the dorsolateral prefrontal
cortex. In most of these areas, gray matter density correlated
with memory success. Decreased functional activation
was found in the left fusiform gyrus, a crucial area for
face processing, and in the dorsolateral prefrontal cortex,
whereas activation of the medial prefrontal cortex was
enhanced. Hence, our data lend strength to the hypothesis
that congenital prosopagnosia is explained by network
dysfunction and suggest that anatomic curtailing of visual
processing in the lingual gyrus plays a substantial role. The
dysfunctional circuitry further encompasses the fusiform
gyrus and the dorsolateral prefrontal cortex, which may
contribute to their difficulties in long-term memory for
complex visual information. Despite their deficits in face
identity recognition, processing of emotion related information
is preserved and possibly mediated by the medial
prefrontal cortex. Congenital prosopagnosia may, therefore,
be a blueprint of differential curtailing in networks of
visual cognition
Telomerase Is Essential for Zebrafish Heart Regeneration.

After myocardial infarction in humans, lost cardiomyocytes are replaced by an irreversible fibrotic scar. In contrast, zebrafish hearts efficiently regenerate after injury. Complete regeneration of the zebrafish heart is driven by the strong proliferation response of its cardiomyocytes to injury. Here we show that, after cardiac injury in zebrafish, telomerase becomes hyperactivated, and telomeres elongate transiently, preceding a peak of cardiomyocyte proliferation and full organ recovery. Using a telomerase-mutant zebrafish model, we found that telomerase loss drastically decreases cardiomyocyte proliferation and fibrotic tissue regression after cryoinjury and that cardiac function does not recover. The impaired cardiomyocyte proliferation response is accompanied by the absence of cardiomyocytes with long telomeres and an increased proportion of cardiomyocytes showing DNA damage and senescence characteristics. These findings demonstrate the importance of telomerase function in heart regeneration and highlight the potential of telomerase therapy as a means of stimulating cell proliferation upon myocardial infarction