Miracle-dz/UniFAR-FTUs huggingface dataset:
Kundt solutions of Minimal Massive 3D Gravity

We construct Kundt solutions of Minimal Massive Gravity theory and show that, similar to Topologically Massive Gravity (TMG), most of them are constant scalar invariant (CSI) spacetimes, that correspond to deformations of round and warped (A)dS. We also find an explicit non-CSI Kundt solution at the merger point. Finally, we give their algebraic classification with respect to the traceless Ricci tensor (Segre classification) and show that their Segre-types match with the types of their counterparts in TMG.
On the moduli part of the Kawamata-Kodaira canonical bundle formula

It is conjectured that the moduli b-divisor of the Kawamata-Kodaira canonical bundle formula associated to a klt-trivial fibration $(X,B)\to Z$ is semi-ample. In this paper, we show the semi-ampleness of an arbitrarily small perturbation of the moduli b-divisor by a fixed appropriate divisor which roughly speaking comes from a section of $K_X+B$. We apply the above result to settle a conjecture of Fujino and Gongyo: if $f\colon X\to Z$ is a smooth surjective morphism of smooth projective varieties with $-K_X$ semi-ample, then $-K_Z$ is also semi-ample. We list several counter-examples to show that this fails without the smoothness assumption on $f$.
Sub-photospheric Shocks in Relativistic Explosions

This paper examines the mechanism of internal shocks in opaque relativistic outflows, in particular in cosmological gamma-ray bursts. The shocks produce neutrino emission and affect the observed photospheric radiation from the explosion. They develop from internal compressive waves and can be of different types depending on the composition of the outflow. (1) Shocks in “photon gas,” with negligible plasma inertia, have a unique structure determined by the force-free condition—zero radiation flux in the plasma rest frame. Radiation dominance over plasma inertia suppresses the formation of collisionless shocks mediated by collective electromagnetic fields. (2) If the outflow is sufficiently magnetized, a strong collisionless subshock develops, which is embedded in a thicker radiation-mediated structure. (3) Waves in outflows with a free neutron component lead to dissipation through nuclear collisions. At large optical depths, shocks have a thickness comparable to the neutron free path, with embedded radiation-mediated and collisionless subshocks. The paper also presents first-principles simulations of magnetized flows filled with photons, demonstrating the formation of shocks and their structure. Simple estimates show that magnetized sub-photospheric shocks are efficient producers of photons and have a great impact on the observed photospheric radiation. The shock structure changes as the outflow expands toward its photosphere. The dissipation is accompanied by strong pair creation, and the -dressed shock carries the photosphere with it up to two decades in radius, emitting a strong pulse of nonthermal radiation.
The Journal of the Southern Association for Information Systems The

Informed by theories of technological innovation, this paper develops and empirically tests a web disclosure adoption model. In order to test the model, a questionnaire was administered to a sample of 775 organizations in an eight-county regional area in the Northeastern United States. Results reveal that Chief Executive Officer (CEO) and organizational characteristics are related to web disclosure adoption. Specifically, there is more disclosure of performance information online when the CEO believes that the web is useful for promoting transparency and accountability, when the organization views the web as a communication or strategic tool, when more employees have technical expertise, and when the board of directors is more supportive of web technology. We found more web disclosure of financial information when the organization possesses the technological readiness for web disclosure. This paper contributes to research by identifying the main factors that facilitate web disclosure adoption in nonprofit contexts.
Locally Helical Surfaces have bounded twisting

A topologically minimal surface may be isotoped into a normal form with respect to a fixed triangulation. If the intersection with each tetrahedron is simply connected, then the pieces of this normal form are triangles, quadrilaterals, and helicoids. Helical pieces can have any number of positive or negative twists. We show here that the net twisting of the helical pieces of any such surface in a given triangulated 3-manifold is bounded.
Open/closed string duality and relativistic fluids

We propose an open/closed string duality in general backgrounds extending previous ideas about open string completeness by Ashoke Sen. Our proposal sets up a general version of holography that works in gravity as a tomographic principle. We argue, in particular, that previous expectations of a supergravity/Dirac-Born-Infeld (DBI) correspondence are naturally embedded in this conjecture and can be tested in a well-defined manner. As an example, we consider the correspondence between open string field theories on extremal D-brane setups in flat space in the large-N, large 't Hooft limit, and asymptotically flat solutions in ten-dimensional type II supergravity. We focus on a convenient long-wavelength regime, where specific effects of higher-spin open string modes can be traced explicitly in the dual supergravity computation. For instance, in this regime we show how the full abelian DBI action arises from supergravity as a straightforward reformulation of relativistic hydrodynamics. In the example of a (2+1)-dimensional open string theory this reformulation involves an abelian Hodge duality. We also point out how different deformations of the DBI action, related to higher-derivative corrections and non-abelian effects, can arise in this context as deformations in corresponding relativistic hydrodynamics.
Distinguishing mutant pretzel knots in concordance

We prove that many pretzel knots of the form $P(2n,m,-2n\pm1,-m)$ are not topologically slice, even though their positive mutants $P(2n, -2n\pm1, m, -m)$ are ribbon. We use the sliceness obstruction of Kirk and Livingston related to the twisted Alexander polynomials associated to prime power cyclic covers of knots.
The Canadian Cluster Comparison Project: weak lensing masses and SZ scaling relations†

The Canadian Cluster Comparison Project is a comprehensive multi-wavelength survey targeting 50 massive X-ray selected clusters of galaxies to examine baryonic tracers of cluster mass and to probe the cluster-to-cluster variation in the thermal properties of the hot intracluster medium. In this paper we present the weak lensing masses, based on the analysis of deep wide-field imaging data obtained using the CanadaFrance-Hawaii-Telescope. The final sample includes two additional clusters that were located in the field-of-view. We take these masses as our reference for the comparison of cluster properties at other wavelengths. In this paper we limit the comparison to published measurements of the Sunyaev-Zel’dovich effect. We find that this signal correlates well with the projected lensing mass, with an intrinsic scatter of 12±5% at � r2500, demonstrating it is an excellent proxy for cluster mass.
Role of SrTiO 3 phonon penetrating into thin FeSe films in the enhancement of superconductivity

The significant role of interfacial coupling in the enhancement of superconductivity in FeSe films on ${\mathrm{SrTiO}}_{3}$ has been widely recognized, but the explicit origin of this coupling is yet to be identified. Here, by surface phonon measurements using high-resolution electron energy loss spectroscopy, we found the electric field generated by Fuchs-Kliewer (F-K) phonon modes of ${\mathrm{SrTiO}}_{3}$ can penetrate into FeSe films and strongly interact with the electrons therein. The mode-specific electron-phonon coupling constant for the $\ensuremath{\sim}92$ meV F-K phonon is $\ensuremath{\sim}0.25$ in single-layer FeSe on ${\mathrm{SrTiO}}_{3}$. With increasing FeSe thickness, the penetrating field intensity decays exponentially, which matches well the observed exponential decay of the superconducting gap. It is unambiguously shown that the ${\mathrm{SrTiO}}_{3}$ F-K phonon penetrating into FeSe is essential for interfacial superconductivity enhancement.
Extreme blazars as counterparts of IceCube astrophysical neutrinos

We explore the correlation of $\gamma$-ray emitting blazars with IceCube neutrinos by using three very recently completed, and independently built, catalogues and the latest neutrino lists. We introduce a new observable, namely the number of neutrino events with at least one $\gamma$-ray counterpart, $N_{\nu}$. In all three catalogues we consistently observe a positive fluctuation of $N_{\nu}$ with respect to the mean random expectation at a significance level of $0.4 - 1.3$ per cent. This applies only to extreme blazars, namely strong, very high energy $\gamma$-ray sources of the high energy peaked type, and implies a model-independent fraction of the current IceCube signal $\sim 10 - 20$ per cent. An investigation of the hybrid photon -- neutrino spectral energy distributions of the most likely candidates reveals a set of $\approx 5$ such sources, which could be linked to the corresponding IceCube neutrinos. Other types of blazars, when testable, give null correlation results. Although we could not perform a similar correlation study for Galactic sources, we have also identified two (further) strong Galactic $\gamma$-ray sources as most probable counterparts of IceCube neutrinos through their hybrid spectral energy distributions. We have reasons to believe that our blazar results are not constrained by the $\gamma$-ray samples but by the neutrino statistics, which means that the detection of more astrophysical neutrinos could turn this first hint into a discovery.
STAR-FORMING ACTIVITY IN THE H ii REGIONS ASSOCIATED WITH THE IRAS 17160–3707 COMPLEX

We present a multiwavelength investigation of star formation activity toward the southern H ii regions associated with IRAS 17160–3707, located at a distance of 6.2 kpc with a bolometric luminosity of 8.3 × 105 L⊙. The ionized gas distribution and dust clumps in the parental molecular cloud are examined in detail using measurements at infrared, submillimeter and radio wavelengths. The radio continuum images at 1280 and 610 MHz obtained using the Giant Metrewave Radio Telescope reveal the presence of multiple compact sources as well as nebulous emission. At submillimeter wavelengths, we identify seven dust clumps and estimate their physical properties such as temperature: 24–30 K, mass: 300–4800 M⊙ and luminosity: 9–317 × 102 L⊙ using modified blackbody fits to the spectral energy distributions (SEDs) between 70 and 870 μm. We find 24 young stellar objects (YSOs) in the mid-infrared, with a few of them coincident with the compact radio sources. The SEDs of the YSOs have been fitted by the Robitaille models and the results indicate that those having radio compact sources as counterparts host massive objects in early evolutionary stages with best fit age ≤0.2 Myr. We compare the relative evolutionary stages of clumps using various signposts such as masers, ionized gas, presence of YSOs and infrared nebulosity, and find six massive star-forming clumps and one quiescent clump. Of the former, five are in a relatively advanced stage and one in an earlier stage.
X-ray spectral variability of LINERs selected from the Palomar sample

Context. Variability is a general property of active galactic nuclei (AGN). The way in which these changes occur at X-rays is not yet clearly understood. In the particular case of low-ionization nuclear emission line region (LINER) nuclei, variations on the timescales from months to years have been found for some objects, but the main driver of these changes is still debated. Aims. The main purpose of this work is to investigate the X-ray variability in LINERs, including the main driver of these variations, and to search for possible differences between type 1 and 2 objects. Methods. We examined the 18 LINERs in the Palomar sample with data retrieved from the Chandra and/or XMM-Newton archives that correspond to observations gathered at different epochs. All the spectra for the same object were fitted simultaneously to study long-term variations. The nature of the variability patterns were studied by allowing different parameters to vary during the spectral fit. Whenever possible, short-term variations from the analysis of the light curves and long-term UV variability were studied. Results. Short-term variations are not reported in X-rays. Three LINERs are classified as non-AGN candidates in X-rays, all of them are Compton-thick candidates; none of them show variations at these frequencies, and two of them vary in the UV. Long-term X-ray variations were analyzed in 12 out of 15 AGN candidates; about half of them showed variability (7 out of the 12). At UV frequencies, most of the AGN candidates with available data are variable (five out of six). Thus, 13 AGN candidates are analyzed at UV and/or X-rays, ten of which are variable at least in one energy band. None of the three objects that do not vary in X-rays have available UV data. This means that variability on long-timescales is very common in LINERs. These X-ray variations are mainly driven by changes in the nuclear power, while changes in absorptions are found only for NGC 1052. We do not find any difference between type 1 and 2 LINERs, neither in the number of variable cases (three out of five type 1 and four out of seven type 2 LINERs), nor in the nature of the variability pattern. We find indications of an anticorrelation between the slope of the power law, Γ, and the Eddington ratio. Conclusions. LINERs are definitely variable sources irrespective of whether they are classified as optical type 1 or 2. Their BH masses, accretion rates, and variability timescales place them in the same plane as more powerful AGN at X-rays. However, our results suggest that the accretion mechanism in LINERs may be different. UV variations of some type 2 LINERs were found, this could support the hypothesis of a torus that disappears at low luminosities.
Journal of Number Theory

Twisted A -harmonic sums are partial sums of a class of zeta values introduced by the ﬁrst author. We prove some new identities for such sums and we deduce properties of analogues of ﬁnite zeta values in the framework of the Carlitz module. In the theory of ﬁnite multiple zeta values as introduced by Kaneko and Zagier, ﬁnite zeta values are all zero and there is no known non-zero ﬁnite multiple zeta value. In the Carlitzian setting the phenomenology is diﬀerent as we can deduce, from our results, the irrationality of certain ﬁnite zeta values. © 2018 Elsevier Inc. All rights reserved.
The complex distribution of recently formed stars. Bimodal stellar clustering in the star-forming region NGC 346

We present a detailed stellar clustering analysis with the a pplication of the two-point correlation function on distinct young stellar ensembles. Our aim is to understand how stellar systems are assembled at the earliest stages of their format ion. Our object of interest is the star-forming region NGC 346 in the Small Magellanic Cloud. It is a young stellar system wellrevealed from its natal environment, comprising complete samples of pre‐main-sequence and upper main-sequence stars, very close to their formation. We apply a comprehensive characterization of the autocorrelation function for both cent rally condensed stellar clusters and self-similar stellar distributions through numerical sim ulations of stellar ensembles. We interpret the observed autocorrelation function of NGC 346 on the basis of these simulations. We find that it can be best explained as the combination of two d istinct stellar clustering designs, a centrally concentrated, dominant at the central pa rt of the star-forming region, and an extended self-similar distribution of stars across the c omplete observed field. The cluster component, similar to non-truncated young star clusters, is determined to have a core radius of � 2.5 pc and a density profile index of � 2.3. The extended fractal component is found with our simulations to have a fractal dimension of � 2.3, identical to that found for the interstellar medium, in agreement to hierarchy induced by turbulence. This suggests that the stellar clustering at a time very near to birth behaves in a complex manner. It is the combined result of the star formation process regulated by turbulence and the early dynamical evolution induced by the gravitational potential of condensed stellar cluste rs.
Triangulation of refined families

We prove the global triangulation conjecture for families of refined p-adic representations under a mild condition. That is, for a refined family, the associated family of (phi, Gamma)-modules admits a global triangulation on a Zariski open and dense subspace of the base that contains all regular non-critical points. We also determine a large class of points which belongs to the locus of global triangulation. Furthermore, we prove that all the specializations of a refined family are trianguline. In the case of the Coleman-Mazur eigencurve, our results provide the key ingredient for showing its properness in a subsequent work.
Far-infrared line emission from high-redshift galaxies

By combining high resolution, radiative transfer cosmological simulations of z~6 galaxies with a sub-grid multi-phase model of their interstellar medium we derive the expected intensity of several far infrared (FIR) emission lines ([C II] 158 micron, [O I] 63 micron, and [N II] 122 micron) for different values of the gas metallicity, Z. For Z = Z_sun the [C II] spectrum is very complex due to the presence of several emitting clumps of individual size < 3 kpc; the peak is displaced from the galaxy center by ~100 km/s. While the [O I] spectrum is also similarly displaced, the [N II] line comes predominantly from the central ionized regions of the galaxy. When integrated over ~500 km/s, the [C II] line flux is 185 mJy km/s; 95% of such flux originates from the cold (T~250 K) H I phase, and only 5% from the warm (T~5000 K) neutral medium. The [O I] and [N II] fluxes are ~6 and ~90 times lower than the [C II] one, respectively. By comparing our results with observations of Himiko, the most extended and luminous Lyman Alpha Emitter (LAE) at z = 6.6, we find that the gas metallicity in this source must be sub-solar. We conclude that the [C II] line from z~6 galaxies is detectable by the ALMA full array in 1.9 < t_ON < 7.7 hr observing time, depending on Z.
n/p-harmonic maps: Regularity for the sphere case

Abstract. We introduce n/-harmonic maps as critical points of the energy where pointwise , for the N-sphere and . This energy combines the non-local behaviour of the fractional harmonic maps introduced by Rivière and the first author with the degenerate arguments of the n-Laplacian. In this setting, we will prove Hölder continuity.
Copositive criteria and boundedness of the scalar potential

To understand physics beyond the Standard Model (SM) it is important to have the precise knowledge of Higgs boson and top quark masses as well as strong coupling. Recently discovered new boson which is likely to be the SM Higgs with mass 123-127 GeV has a submissive impact on the stability of the new physics beyond standard model (BSM). The beyond standard model scenarios that include many scalar fields posses scalar potential with many quartic couplings. Due to the complicated structures of such scalar potentials it is indeed difficult to adjudge the stability of the vacuum. Thus one needs to formulate a proper prescription for computing the vacuum stability criteria. In this paper we have used the idea of copositive matrices to deduce the conditions that guarantee the boundedness of the scalar potential. We have discussed the basic idea behind the copositivity and then used that to determine the vacuum stability criteria for the Left-Right symmetric models with doublet, and triplet scalars and Type-II seesaw. As this idea is based on the strong mathematical arguments it helps to compute simple and unique stability criteria embracing the maximum allowed parameter space.
The UK Infrared Telescope M33 monitoring project – III. Feedback from dusty stellar winds in the central square kiloparsec

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. In this third paper of the series, we measure the dust production and rates of mass loss by the pulsating Asymptotic Giant Branch (AGB) stars and red supergiants. To this aim, we combined our time-averaged nearIR photometry with the multi-epoch mid-IR photometry obtained with the Spitzer Space Telescope. The mass-loss rates are seen to increase with increasing strength of pulsation and with increasing bolometric luminosity. Low-mass stars lose most of their mass through stellar winds, but even super-AGB stars and red supergiants lose � 40% of their mass via a dusty stellar wind. More than three-quarters of the dust return is oxygenous. We construct a 2-D map of the mass-return rate, showing a radial decline but also local enhancements due to agglomerations of massive stars. We estimate a total mass-loss rate of 0.004–0.005 M⊙ yr −1 kpc −2 , increasing to � 0.006 M⊙ yr −1 kpc −2 when accounting for eruptive mass loss (e.g., supernovae); comparing this to the current star formation rate of � 0.03 M⊙ yr −1 kpc −2 we conclude that star formation in the central region of M33 can only be sustained if gas is accreted from further out in the disc or from circum-galactic regions.
Accretion and jet power in active galactic nuclei

The classical diagrams of radio loudness and jet power as a function of mass and accretion rate of the central spacetime singularity in active galactic nuclei are reanalyzed by including the data of the recently discovered powerful relativistic jets in Narrow-Line Seyfert 1 Galaxies. The results are studied in the light of the known theories of relativistic jets, indicating that, although the Blandford-Znajek mechanism is sufficient to explain the power radiated by BL Lac Objects, it fails to completely account for the power from quasars and Narrow-Line Seyfert 1 Galaxies. This favors the scenario outlined by Cavaliere & D'Elia of a composite jet, with a magnetospheric core plus a hydromagnetic component emerging when the accretion power increases and the disk becomes radiation-pressure dominated. A comparison with Galactic compact objects is also made, finding some striking similarities, indicating that since neutron stars are low-mass jet systems analogous to black holes, Narrow-Line Seyfert 1 Galaxies are low-mass counterparts of blazars.
Lattice Vibrational Modes and Raman Scattering Spectra of Strained Phosphorene

Strain is prominent in fabricated samples of two-dimensional semiconductors and it also serves as an exploitable tool for engineering their properties. However, quantifying strain and characterizing its spatially inhomogeneous distribution across a material are challenging tasks. Here, we report the lattice vibrational modes and corresponding Raman spectra of strained monolayer black phosphorus (phosphorene) by first-principles simulations. We show that frequencies of vibrational modes of phosphorene and their Raman scattering peaks exhibit substantial and distinct shifts according to the types and size of strain. Therefore, combined with high spatial-resolution Raman scattering measurements, our calculated results can quantify strain distributions in phosphorene. This information is essential for understanding structures of future large-scale fabrication and strain engineering of phosphorene.