pinecone/core-2020-05-10-deduplication huggingface dataset:
General non-rotating perfect-fluid solution with an abelian spacelike $C_3$ including only one isometry

The general solution for non-rotating perfect-fluid spacetimes admitting one Killing vector and two conformal (non-isometric) Killing vectors spanning an abelian three-dimensional conformal algebra (C_3) acting on spacelike hypersurfaces is presented. It is of Petrov type D; some properties of the family such as matter contents are given. This family turns out to be an extension of a solution recently given in \cite{SeS} using completely different methods. The family contains Friedman-Lemaître-Robertson-Walker particular cases and could be useful as a test for the different FLRW perturbation schemes. There are two very interesting limiting cases, one with a non-abelian G_2 and another with an abelian G_2 acting non-orthogonally transitively on spacelike surfaces and with the fluid velocity non-orthogonal to the group orbits. No examples are known to the authors in these classes
On First Order Formalism in String Theory

We consider the first order formalism in string theory, providing a new
off-shell description of the nontrivial backgrounds around an "infinite
metric". The OPE of the vertex operators, corresponding to the background
fields in some "twistor representation", and conditions of conformal invariance
results in the quadratic equation for the background fields, which appears to
be equivalent to the Einstein equations with a Kalb-Ramond B-field and a
dilaton. Using a new representation for the Einstein equations with B-field and
dilaton we find a new class of solutions including the plane waves for metric
(graviton) and the B-field. We discuss the properties of these background
equations and main features of the BRST operator in this approach.Comment: LaTeX2e, 18 pages, Phys. Lett. B, in press, corrected typo
Search for R-Parity Violating Production of Single Sneutrinos in $e^{+}e^{-}$ Collisions at $\sqrt{s}$ = 189-209 GeV

A search for single sneutrino production under the assumption that $R$-parity is violated via a single dominant $LL\bar{E}$ coupling is presented. This search considers the process ${\rm e} \gamma \;{\smash{\mathop{\rightarrow}}}\;\tilde{\nu}\ell$ and is performed using the data collected by the ALEPH detector at centre-of-mass energies from 189\,GeV up to 209\,GeV corresponding to an integrated luminosity of 637.1\,$\mathrm{pb}^{-1}$. The numbers of observed candidate events are in agreement with Standard Model expectations and 95\% confidence level upper limits on five of the $LL\bar{E}$ couplings are given as a function of the assumed sneutrino mass
A New Orientifold of C^2/Z_N and Six-dimensional RG Fixed Points

We discuss the consistency conditions of a novel orientifold projection of
type IIB string theory on C^2/Z_N singularities, in which one mods out by the
combined action of world-sheet parity and a geometric operation which exchanges
the two complex planes. The field theory on the world-volume of D5-brane probes
defines a family of six-dimensional RG fixed points, which had been previously
constructed using type IIA configurations of NS-branes and D6-branes in the
presence of O6-planes. Both constructions are related by a T-duality
transforming the set of NS-branes into the C^2/Z_N singularity. We also
construct additional models, where both the standard and the novel orientifold
projections are imposed. They have an interesting relation with orientifolds of
D_K singularities, and provide the T-duals of certain type IIA configurations
containing both O6- and O8-planes.Comment: Latex, 18 pages Repot-no: IASSNS-HEP-99/9
Hyperkaehler structures and infinite-dimensional Grassmannians

In this paper, we describe an example of a hyperkaehler quotient of a Banach
manifold by a Banach Lie group. Although the initial manifold is not
diffeomorphic to a Hilbert manifold (not even to a manifold modelled on a
reflexive Banach space), the quotient space obtained is a Hilbert manifold,
which can furthermore be identified either with the cotangent space of a
connected component of the restricted Grassmannian or with a natural
complexification of this connected component, thus proving that these two
manifolds are isomorphic hyperkaehler manifolds. In addition, Kaehler
potentials are computed using Kostant-Souriau's theory of prequantization.Comment: The title was initially `Hyperkahler structures on the cotangent
  bundle of the restricted grassmannian and on a natural complexification of
  the restricted grassmannian'. This version includes minor change
Multifragmentation of very heavy nuclear systems (III): fragment
  velocity correlations and event topology at freeze-out

Kinetic energy spectra and fragment velocity correlations, simulated by means
of stochastic mean-field calculations, are successfully confronted with
experimental data for single multifragmenting sources prepared at the same
excitation energy per nucleon in 32 AMeV 129Xe+natSn and 36 AMeV 155Gd+natU
central collisions. Relying thus on simulations, average freeze-out times of
200-240 fm/c are estimated The corresponding spatial distributions of fragments
are more compact for the lighter system (~3-4V\_0 vs ~8V\_0).Comment: 20 pages; 9 figures; To be published in Nuclear Physics
Finite approximations to coherent choice.

This paper studies and bounds the effects of approximating loss functions and credal sets on choice functions, under very weak assumptions. In particular, the credal set is assumed to be neither convex nor closed. The main result is that the effects of approximation can be bounded, although in general, approximation of the credal set may not always be practically possible. In case of pairwise choice, I demonstrate how the situation can be improved by showing that only approximations of the extreme points of the closure of the convex hull of the credal set need to be taken into account, as expected
Does generating examples aid proof production ?

Many mathematics education researchers have suggested that asking learners to generate examples of mathematical concepts is an effective way of learning about novel concepts. To date, however, this suggestion has limited empirical support. We asked undergraduate students to study a novel concept by either tackling example generation tasks or reading worked solutions to these tasks. Contrary to suggestions in the literature, we found no advantage for the example generation group on subsequent proof production tasks. From a second study, we found that undergraduate students overwhelmingly adopt a trial and error approach to example generation and suggest that different example generation strategies may result in different learning gains. We conclude by arguing that the teaching strategy of example generation is not yet understood well enough to be a viable pedagogical recommendation
The HI Tully-Fisher Relation of Early-Type Galaxies

We study the HI K-band Tully-Fisher relation and the baryonic Tully-Fisher
relation for a sample of 16 early-type galaxies, taken from the ATLAS3D sample,
which all have very regular HI disks extending well beyond the optical body (>
5 R_eff). We use the kinematics of these disks to estimate the circular
velocity at large radii for these galaxies. We find that the Tully-Fisher
relation for our early-type galaxies is offset by about 0.5-0.7 magnitudes from
the relation for spiral galaxies. The residuals with respect to the spiral
Tully-Fisher relation correlate with estimates of the stellar mass-to-light
ratio, suggesting that the offset between the relations is mainly driven by
differences in stellar populations. We also observe a small offset between our
Tully-Fisher relation with the relation derived for the ATLAS3D sample based on
CO data representing the galaxies' inner regions (< 1 R_eff). This indicates
that the circular velocities at large radii are systematically 10% lower than
those near 0.5-1 R_eff, in line with recent determinations of the shape of the
mass profile of early-type galaxies. The baryonic Tully-Fisher relation of our
sample is distinctly tighter than the standard one, in particular when using
mass-to-light ratios based on dynamical models of the stellar kinematics. We
find that the early-type galaxies fall on the spiral baryonic Tully-Fisher
relation if one assumes M/L_K = 0.54 M_sun/L_sun for the stellar populations of
the spirals, a value similar to that found by recent studies of the dynamics of
spiral galaxies. Such a mass-to-light ratio for spiral galaxies would imply
that their disks are 60-70% of maximal. Our analysis increases the range of
galaxy morphologies for which the baryonic Tully-Fisher relations holds,
strengthening previous claims that it is a more fundamental scaling relation
than the classical Tully-Fisher relation.Comment: Accepted for publication in Astronomy & Astrophysic
When cheaper is better: Fee determination in the market for equity mutual funds

In this paper, we develop a model of the market for equity mutual funds that captures three key characteristics of this market. First, there is competition among funds. Second, fund managers’ ability is not observed by investors before making their investment decisions. Third, some investors do not make optimal use of all available information. The main results of the paper are that (1) price competition is compatible with positive mark-ups in equilibrium, and (2) worse-performing funds set fees that are greater or equal to those set by better-performing funds. These predictions are supported by available empirical evidence.Publicad
Measurement of vacuum pressure with a magneto-optical trap : a pressure-rise method

This research was supported by UK EPSRC grant GR/T08272/01, IOP Scotland and the Leverhulme Trust Research Project Grant RPG-2013-074.The lifetime of an atom trap is often limited by the presence of residual background gases in the vacuum chamber. This leads to the lifetime being inversely proportional to the pressure. Here we use this dependence to estimate the pressure and to obtain pressure rate-of-rise curves, which are commonly used in vacuum science to evaluate the performance of a system. We observe different rates of pressure increase in response to different levels of outgassing in our system. Therefore we suggest that this is a sensitive method which will find useful applications in cold atom systems, in particular where the inclusion of a standard vacuum gauge is impractical.PostprintPeer reviewe
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 8 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three leptons and missing transverse momentum is presented. The analysis is based on 20.3 fb−1 of s√ = 8 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with the Standard Model expectations and limits are set in R-parity-conserving phenomenological Minimal Supersymmetric Standard Models and in simplified supersymmetric models, significantly extending previous results. For simplified supersymmetric models of direct chargino (χ˜±1) and next-to-lightest neutralino (χ˜02) production with decays to lightest neutralino (χ˜01) via either all three generations of sleptons, staus only, gauge bosons, or Higgs bosons, (χ˜±1) and (χ˜02) masses are excluded up to 700 GeV, 380 GeV, 345 GeV, or 148 GeV respectively, for a massless (χ˜01)
Absorption cross-sections of hole polarons in glassy and β-phase polyfluorene

Absorption induced by electrochemically injected holes is studied in poly-9,9-dioctylfluorene (PFO) films. Injected charges form positive polarons which are delocalised over four fluorene units in the glassy phase and about seven fluorene units in its β-phase. Polaron absorption cross-sections at the 640 nm peak are similar to the published values of chemically reduced oligofluorenes in solution. The absorption cross-section of polaron in the β-phase at 470 nm is about eight times smaller than the stimulated emission cross-section derived from published data. This indicates that β-phase-rich PFO is an attractive candidate for a light-emitting layer in double-heterostructure organic laser diodes.F. Montilla is grateful for financial support provided by Ministerio de Economía y Competitividad (Ramón y Cajal RYC1463/06 and José Castillejo JC2009-00227 Programs). We are also grateful to the Engineering and Physical Sciences Research Council for financial support
Contemporaneous observations of the radio galaxy NGC 1275 from radio to very high energy gamma-rays

Aims. The radio galaxy NGC 1275, recently identified as a very high energy (VHE, >100 GeV) gamma-ray emitter by MAGIC, is one of the few non-blazar active galactic nuclei detected in the VHE regime. The purpose of this work is to better understand the origin of the gamma-ray emission and locate it within the galaxy. Methods. We studied contemporaneous multifrequency observations of NGC 1275 and modeled the overall spectral energy distribution. We analyzed unpublished MAGIC observations carried out between October 2009 and February 2010, and the previously published observations taken between August 2010 and February 2011. We studied the multiband variability and correlations by analyzing data of Fermi-LAT in the 100 MeV-100 GeV energy band, as well as Chandra (X-ray), KVA (optical), and MOJAVE (radio) data taken during the same period. Results. Using customized Monte Carlo simulations corresponding to early MAGIC stereoscopic data, we detect NGC 1275 also in the earlier MAGIC campaign. The flux level and energy spectra are similar to the results of the second campaign. The monthly light curse above 100 GeV shows a hint of variability at the 3.6 sigma level. In the Fermi-LAT hand, both flux and spectral shape variabilities are reported. The optical light curve is also variable and shows a clear correlation with the gamma-ray flux above 100 MeV. In radio, three compact components are resolved in the innermost part of the jet. One of these components shows a similar trend as the Fermi-LAT and KVA light curves. The gamma-ray spectra measured simultaneously with MAGIC and Fermi-LAT from 100 MeV to 650 GeV can be well fitted either by a log-parabola or by a power-law with a subexponential cutoff for the two observation campaigns. A single-zone synchrotron-self-Compton model, with an electron spectrum following a power-law with an exponential cutoff, can explain the broadband spectral energy distribution and the multifrequency behavior of the source. However, this model suggests an untypical low bulk-Lorentz factor or a velocity alignment closer to the line of sight than the parsec-scale radio jet
Nearby supernova host galaxies from the CALIFA Survey

We use optical integral field spectroscopy (IFS) of nearby supernova (SN) host galaxies (0.005 < z < 0.03) provided by the Calar Alto Legacy Integral Field Area (CALIFA) Survey with the goal of finding correlations in the environmental parameters at the location of different SN types. In this first study of a series we focus on the properties related with star formation (SF). We recover the sequence in association of different SN types to the star-forming regions by using several indicators of the ongoing and recent SF related to both the ionized gas and the stellar populations. While the total ongoing SF is on average the same for the three SN types, SNe Ibc/IIb tend to occur closer to star-forming regions and in higher SF density locations than SNe II and SNe Ia; the latter shows the weakest correlation. SNe Ia host galaxies have masses that are on average similar to 0.3-0.8 dex higher than those of the core collapse (CC) SNe hosts because the SNe Ia hosts contain a larger fraction of old stellar populations. Using the recent SN Ia delay-time distribution and the SFHs of the galaxies, we show that the SN Ia hosts in our sample are expected to produce twice as many SNe Ia as the CC SN hosts. Since both types occur in hosts with a similar SF rate and hence similar CC SN rate, this can explain the mass difference between the SN Ia and CC SN hosts, and reinforces the finding that at least part of the SNe Ia originate from very old progenitors. By comparing the mean SFH of the eight least massive galaxies with that of the massive SF SN Ia hosts, we find that the low-mass galaxies formed their stars during a longer time (0.65%, 24.46%, and 74.89% in the intervals 0-0.42 Gyr, 0.42-2.4 Gyr, and >2.4 Gyr, respectively) than the massive SN Ia hosts (0.04%, 2.01%, and 97.95% in these intervals). We estimate that the low-mass galaxies produce ten times fewer SNe Ia and three times fewer CC SNe than the high-mass group. Therefore the ratio between the number of CC SNe and SNe Ia is expected to increase with decreasing galaxy mass. CC SNe tend to explode at positions with younger stellar populations than the galaxy average, but the galaxy properties at SNe Ia locations are one average the same as the global galaxy properties
The Gaia-ESO survey: metallicity of the chamaeleon i star-forming region

Context. Recent metallicity determinations in young open clusters and star-forming regions suggest that the latter may be characterized by a slightly lower metallicity than the Sun and older clusters in the solar vicinity. However, these results are based on small  statistics and inhomogeneous analyses. The Gaia-ESO Survey is observing and homogeneously analyzing large samples of stars in several young clusters and star-forming regions, hence allowing us to further investigate this issue.\ud
Aims. We present a new metallicity determination of the Chamaeleon I star-forming region, based on the products distributed in the first internal release of the Gaia-ESO Survey.\ud
Methods. 48 candidate members of Chamaeleon I have been observed with the high-resolution spectrograph UVES. We use the surface gravity, lithium line equivalent width and position in the Hertzsprung-Russell diagram to confirm the cluster members and we use the iron abundance to derive the mean metallicity of the region.\ud
Results. Out of the 48 targets, we confirm 15 high probability members. Considering the metallicity measurements for 9 of them, we find that the iron abundance of Chamaeleon I is slightly subsolar with a mean value [Fe/H]= −0.08 ± 0.04 dex. This result is in agreement with the metallicity determination of other nearby star-forming regions and suggests that the chemical pattern of the youngest stars in the solar neighborhood is indeed more metal-poor than the Sun. We argue that this evidence may be related to the chemical distribution of the Gould Belt that contains most of the nearby star-forming regions and young clusters
Multiple orthogonal polynomials of mixed type: Gauss-Borel factorization and the multi-component 2D Toda hierarchy

Multiple orthogonality is considered in the realm of a Gauss-Borel factorization problem for a semi-infinite moment matrix. Perfect combinations of weights and a finite Borel measure are constructed in terms of M-Nikishin systems. These perfect combinations ensure that the problem of mixed multiple orthogonality has a unique solution, that can be obtained from the solution of a Gauss-Borel factorization problem for a semi-infinite matrix, which plays the role of a moment matrix. This leads to sequences of multiple orthogonal polynomials, their duals and second kind functions. It also gives the corresponding linear forms that are bi-orthogonal to the dual linear forms. Expressions for these objects in terms of determinants from the moment matrix are given, recursion relations are found, which imply a multi-diagonal Jacobi type matrix with snake shape, and results like the ABC theorem or the Christoffel-Darboux formula are re-derived in this context (using the factorization problem and the generalized Hankel symmetry of the moment matrix). The connection between this description of multiple orthogonality and the multi-component 2D Toda hierarchy, which can be also understood and studied through a Gauss-Borel factorization problem, is discussed. Deformations of the weights, natural for M-Nikishin systems, are considered and the correspondence with solutions to the integrable hierarchy, represented as a collection of Lax equations, is explored. Corresponding Lax and Zakharov-Shabat matrices as well as wave functions and their adjoints are determined. The construction of discrete flows is discussed in terms of Miwa transformations which involve Darboux transformations for the multiple orthogonality conditions. The bilinear equations are derived and the tau-function representation of the multiple orthogonality is given
Morphological parameters of a Spitzer survey of stellar structure in galaxies

The morphology of galaxies can be quantified to some degree using a set of scale-invariant parameters. Concentration (C), asymmetry (A), smoothness (S), the Gini index (G), the relative contribution of the brightest pixels to the second-order moment of the flux (M_20), ellipticity (E), and the Gini index of the second-order moment (G_M ) have all been applied to morphologically classify galaxies at various wavelengths. Here, we present a catalog of these parameters for the Spitzer Survey of stellar structure in Galaxies, a volume-limited, near-infrared (NIR) imaging survey of nearby galaxies using the 3.6 and 4.5 μm channels of the Infrared Array Camera on board the Spitzer Space Telescope. Our goal is to provide a reference catalog of NIR quantified morphology for high-redshift studies and galaxy evolution models with enough detail to resolve stellar mass morphology. We explore where normal, non-interacting galaxies—those typically found on the Hubble tuning fork—lie in this parameter space and show that there is a tight relation between concentration (C_82) and M_20 for normal galaxies. M_20 can be used to classify galaxies into earlier and later types (i.e., to separate spirals from irregulars). Several criteria using these parameters exist to select systems with a disturbed morphology, i.e., those that appear to be undergoing a tidal interaction. We examine the applicability of these criteria to Spitzer NIR imaging. We find that four relations, based on the parameters A and S, G and M_20, G_M,  C, and M_20, respectively, select outliers in morphological parameter space, but each selects different subsets of galaxies. Two criteria (G_M > 0.6, G > –0.115 × M_20 + 0.384) seem most appropriate to identify possible mergers and the merger fraction in NIR surveys. We find no strong relation between lopsidedness and most of these morphological parameters, except for a weak dependence of lopsidedness on concentration and M_20
The clinical and biological impact of new pathogen inactivation technologies on platelet concentrates.

Since 1990, several techniques have been developed to photochemically inactivate pathogens in platelet concentrates, potentially leading to safer transfusion therapy. The three most common methods are amotosalen/UVA (INTERCEPT Blood System), riboflavin/UVA-UVB (MIRASOL PRT), and UVC (Theraflex-UV). We review the biology of pathogen inactivation methods, present their efficacy in reducing pathogens, discuss their impact on the functional aspects of treated platelets, and review clinical studies showing the clinical efficiency of the pathogen inactivation methods and their possible toxicity
Coherent J/psi photoproduction in ultra-peripheral Pb-Pb collisions at root s(NN)=2.76 TeV

The ALICE Collaboration has made the first measurement at the LHC of J/psi photoproduction in ultra-peripheral Pb-Pb collisions at root s(NN) = 2.76 TeV. The J/psi is identified via its dimuon decay in the forward rapidity region with the muon spectrometer for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 55 mu b(-1). The cross section for coherent J/psi production in the rapidity interval -3.6 < y < -2.6 is measured to be d sigma(coh)(J/psi)/dy = 1.00 +/- 0.18(stat)(-0.26)(+0.24)(syst) mb. The result is compared to theoretical models for coherent J/psi production and found to be in good agreement with those models which include nuclear gluon shadowing