Miracle-dz/UniFAR-FTUs huggingface dataset:
Quantum corrections to quartic inflation with a non-minimal coupling: metric vs. Palatini

We study models of quartic inflation where the inflaton field ϕ is coupled non-minimally to gravity, ξ ϕ2 R, and perform a study of quantum corrections in curved space-time at one-loop level. We specifically focus on comparing results between the metric and Palatini theories of gravity. Transformation from the Jordan to the Einstein frame gives different results for the two formulations and by using an effective field theory expansion we derive the appropriate β-functions and the renormalisation group improved effective potentials in curved space for both cases in the Einstein frame. In particular, we show that in both formalisms the Einstein frame depends on the order of perturbation theory but that the flatness of the potential is unaltered by quantum corrections.
Expanding profit and power. The National Union of Road Transport Workers in Nigeria

ABSTRACT This article explores the power exercised by the National Union of Road Transport Workers (NURTW) over the transport workers in Lagos (Nigeria). With the privatisation of transport and the regulation of motor parks transferred from local governments to NURTW, the union has been able to expand the power of unionist leaders who have developed new managerial techniques to increase their own profits. The NURTW case reflects the adaptation of neoliberal norms within a union at the expense of its workers. The article suggests that union power over workers is as necessary a field of research as the recent renewal on power resources approach exploring the capacity of unions to empower workers.
An Ultradeep Chandra Catalog of X-Ray Point Sources in the Galactic Center Star Cluster

We present an updated catalog of X-ray point sources in the inner 500″ (∼20 pc) of the Galactic center (GC), where the nuclear star cluster (NSC) stands, based on a total of ∼4.5 Ms of Chandra observations taken from 1999 September to 2013 April. This ultradeep data set offers unprecedented sensitivity for detecting X-ray sources in the GC, down to an intrinsic 2–10 keV luminosity of 1.0 × 1031 erg s−1. A total of 3619 sources are detected in the 2–8 keV band, among which ∼3500 are probable GC sources and ∼1300 are new identifications. The GC sources collectively account for ∼20% of the total 2–8 keV flux from the inner 250″ region where detection sensitivity is the greatest. Taking advantage of this unprecedented sample of faint X-ray sources that primarily traces the old stellar populations in the NSC, we revisit global source properties, including long-term variability, cumulative spectra, luminosity function, and spatial distribution. Based on the equivalent width and relative strength of the iron lines, we suggest that in addition to the arguably predominant population of magnetic cataclysmic variables (CVs), nonmagnetic CVs contribute substantially to the detected sources, especially in the lower-luminosity group. On the other hand, the X-ray sources have a radial distribution closely following the stellar mass distribution in the NSC, but much flatter than that of the known X-ray transients, which are presumably low-mass X-ray binaries (LMXBs) caught in outburst. This, together with the very modest long-term variability of the detected sources, strongly suggests that quiescent LMXBs are a minor (less than a few percent) population.
How Black Holes Grow

A summary of how black holes grow in full, non-linear general relativity is presented. Specifically, a notion of "dynamical horizons" is introduced and expressions of fluxes of energy and angular momentum carried by gravitational waves across these horizons are obtained. Fluxes are local and the energy flux is positive. Change in the horizon area is related to these fluxes. The flux formulae also give rise to balance laws analogous to the ones obtained by Bondi and Sachs at null infinity and provide generalizations of the first and second laws of black hole mechanics.
Determinants of Hotel Brand Image: A Unified Model of Customer-Based Brand Equity

This study aims to find the factors affecting the brand image of hotels applying a unified model of customer-based brand equity. Additionally, it tests the moderating effect of tourism management in the relationship between the determining factors and brand image of hotels. Responses were gathered from the customers of some selected Bangladeshi hotels in four and five-star category using a multi-stage sampling procedure. The partial least square structural equation modeling (PLS-SEM) was used to test the hypotheses of this study. Corporate social responsibility was found to be the most significant, followed by brand superiority, brand association, brand awareness, and brand resonance. It was found that the relationship between brand superiority and brand image was moderated by tourism management; the relationship between brand resonance and brand image was also found to be moderated by tourism management. The findings of this study bear implications both in theoretical and practical aspects. differentiate a particular brand from the competing ones. Then brand awareness can be formed by brand attributes which might influence brand image. Organizations can form brand associations by providing appealing benefits which create favorable image. Strong brand image can also be built through active brand attachment resulting from brand resonance. The present study also found that CSR practices by the hotels also play a critical role in creating favorable image in the minds of the customers which might help build strong brand image. The proposed model also suggests that better tourism management can be an important platform for building favorable brand image for the hospitality industry.
Revisiting the Tale of Hercules: How Stars Orbiting the Lagrange Points Visit the Sun

We propose a novel explanation for the Hercules stream consistent with recent measurements of the extent and pattern speed of the Galactic bar. We have adapted a made-to-measure dynamical model tailored for the Milky Way to investigate the kinematics of the solar neighborhood (SNd). The model matches the 3D density of the red clump giant stars (RCGs) in the bulge and bar as well as stellar kinematics in the inner Galaxy, with a pattern speed of 39 km s−1 kpc−1. Cross-matching this model with the Gaia DR1 TGAS data combined with RAVE and LAMOST radial velocities, we find that the model naturally predicts a bimodality in the U–V-velocity distribution for nearby stars which is in good agreement with the Hercules stream. In the model, the Hercules stream is made of stars orbiting the Lagrange points of the bar which move outward from the bar’s corotation radius to visit the SNd. While the model is not yet a quantitative fit of the velocity distribution, the new picture naturally predicts that the Hercules stream is more prominent inward from the Sun and nearly absent only a few 100 pc outward of the Sun, and plausibly explains that Hercules is prominent in old and metal-rich stars.
Penrose junction conditions extended: impulsive waves with gyratons

We generalize the classical junction conditions for constructing impulsive gravitational waves by the Penrose "cut and paste" method. Specifically, we study nonexpanding impulses which propagate in spaces of constant curvature with any value of the cosmological constant (that is Minkowski, de Sitter, or anti-de Sitter universes) when additional off-diagonal metric components are present. Such components encode a possible angular momentum of the ultra-relativistic source of the impulsive wave - the so called gyraton. We explicitly derive and analyze a specific transformation that relates the distributional form of the metric to a new form which is (Lipschitz) continuous. Such a transformation automatically implies an extended version of the Penrose junction conditions. It turns out that the conditions for identifying points of the background spacetime across the impulse are the same as in the original Penrose "cut and paste" construction, but their derivatives now directly represent the influence of the gyraton on the axial motion of test particles. Our results apply both for vacuum and nonvacuum solutions of Einstein's field equations, and can also be extended to other theories of gravity.
Survival status and predictors of mortality among mechanically ventilated COVID-19 patients in Addis Ababa COVID-19 Care Centers, Ethiopia: A survival analysis

Background: The COVID-19 pandemic has caused stress on the health care system of many countries worldwide. To accommodate the growing number of critically ill patients requiring mechanical ventilation, hospitals expanded and tried to meet overwhelming demands. Despite this, outcomes of patients after mechanical ventilation were devastating, with high mortality rates. Therefore, this study investigated the survival status and predictors of mortality among mechanically ventilated COVID-19 patients. Methods: A retrospective cohort study was applied on the patient charts of 496 critically ill and mechanically ventilated COVID-19 patients at intensive care units of Addis Ababa COVID-19 Care Centers from September 2020 to October 2021. Data were collected using a data extraction checklist and entered into Epi data manager. Then, data were transferred to STATA V-14 for cleaning and analysis. The cox-proportional hazard regression model was used for analysis. Covariates with p-value ≤0.20 in the bivariate analysis were fitted to multivariate analysis after the model fitness test. Finally, statistical significance was decided at p-value <0.05, and hazard ratios were used to determine the strength of associations. Results: Of the 496 patients, 63.3% had died. The incidence rate of mortality was 56.7 (95% CI: 50.80, 63.37) per 1,000 person-days of observation, with 5534 person-day observations recorded. Advanced age (>60 years old) (adjusted hazard ratio (AHR)=1.86; 95% CI: 1.09, 3.15) and being invasively ventilated (AHR=2.02; 95% CI: 1.25, 3.26) were associated with increased risk of mortality. Furthermore, presence of diabetes (AHR=1.50; 95% CI: 1.09, 2.08), shock (AHR=1.99; 95% CI: 1.12, 3.52), and delirium (AHR=1.60; 95% CI: 1.05, 2.44) were significantly associated with increased mortality. Conclusions: Clear directions are needed in the recommendation of non-invasive versus invasive ventilation, especially among elderly patients. The controversy of when to intubate (early versus late) needs to be clarified as well. Early detection and prompt management of shock is paramount.
Physics of the Merging Clusters Cygnus A, A3667, and A2065

We present ASCA gas temperature maps of the nearby merging galaxy clusters Cygnus A, A3667, and A2065. Cygnus A appears to have a particularly simple merger geometry that allows an estimate of the subcluster collision velocity from the observed temperature variations. We estimate it to be ~2000 km s-1. Interestingly, this is similar to the free-fall velocity that the two Cygnus A subclusters should have achieved at the observed separation, suggesting that the merger has been effective in dissipating the kinetic energy of gas halos into thermal energy, without channeling its major fraction elsewhere (e.g., into turbulence). In A3667 we may be observing a spatial lag between the shock front seen in the X-ray image and the corresponding rise of the electron temperature. A lag of the order of hundreds of kiloparsecs is possible because of the combination of thermal conduction and a finite electron-ion equilibration time. Forthcoming better spatial resolution data will allow a direct measurement of these phenomena in the cluster gas using such lags. A2065 has gas density peaks coincident with two central galaxies. A merger with the collision velocity estimated from the temperature map should have swept away such peaks if the subcluster total mass distributions had flat cores in the centers. The fact that the peaks have survived (or quickly reemerged) suggests that the gravitational potential is also strongly peaked. Finally, the observed specific entropy variations in A3667 and Cygnus A indicate that energy injection from a single major merger may be of the order of the full thermal energy of the gas. We hope that these order-of-magnitude estimates will encourage further work on hydrodynamic simulations, as well as a more quantitative representation of the simulation results, in anticipation of the Chandra and XMM data.
Phenomenology of jet physics in the BFKL formalism at NLO

We study jet physics in the high energy regime of QCD. Based on the NLO BFKL equation, we construct a vertex for the production of a jet at central rapidity in k_T-factorization. A jet algorithm is introduced, and we take special care of the separation of multi-Regge and quasi-multi-Regge kinematics. The connection with the energy scale of the evolution is investigated in detail. The result is discussed for two situations: scattering of highly virtual photons, which requires a symmetric energy scale to separate the impact factors from the gluon Green's function, and hadron-hadron collisions, where a non-symmetric scale choice is needed. For the second case we are able to define a NLO unintegrated gluon density, valid in the small-x regime, and give the evolution equation for this density as well. In the second part, we examine the angular decorrelation of Mueller-Navelet jets. Using an operator formalism in the space of anomalous dimension and conformal spin, we implement the NLO BFKL Green's function to study the rapidity dependence of angular decorrelations. We incorporate the necessary summation of collinearly enhanced corrections beyond NLO accuracy. We compare our results with data from the Tevatron ppbar-collider and provide predictions for the LHC as well. We also extend our study to the angular decorrelation between a forward jets and the electron in deep inelastic ep scattering. The angular decorrelation has not been measured in DIS so far, but we give theoretical results for this observable which already implement the experimental cuts.
Symmetries at the black hole horizon

We determine the asymptotic symmetry group of Killing horizons by choosing Gaussian null coordinates in the neighbourhood of the horizon and boundary conditions that respect the leading order terms in the metric. The analysis divides naturally into the two cases of subextremal and extremal horizons. In general, we find rather involved asymptotic symmetry generators that nevertheless involve supertranslations and Killing vectors on the compact horizon. The most striking observation is the difference in the dependence on the coordinate along the horizon; we relate this to the redshift effect for subextremal horizons. We consider the spherically symmetric case as a special and illuminating example.
Extended [C I] and 13CO (5 → 4) Emission in M17SW

We mapped a 13 × 22 pc region in emission from 492 GHz [C I] and, for the first time, 551 GHz 13CO (5 → 4) in the giant molecular cloud M17SW. The morphologies of the [C I] and 13CO emission are strikingly similar. The extent and intensity of the [C I] and 13CO (5 → 4) emission is explained as arising from photodissociation regions on the surfaces of embedded molecular clumps. Modeling of the 13CO (5 → 4) emission in comparison to 13CO (1 → 0) indicates a temperature gradient across the cloud, peaking to at least 63 K near the M17 ionization front and decreasing to at least 20 K at the western edge of the cloud. We see no correlation between gas density and column density. The beam-averaged column density of C I in the core is 1 × 1018 cm-2, and the mean column density ratio N(C I)/N(CO) is about 0.4. The variations of N(C I)/N(CO) with position in M17SW indicate a similar clump size distribution throughout the cloud.
On the Statistics of Acceleration and Loss of Relativistic Electrons in the Outer Radiation Belt: A Superposed Epoch Analysis

We investigate the response of the outer Van Allen belt electrons to various types of solar wind and magnetospheric disturbances. We use electron phase space density calculations as well as concurrent Pc5 and chorus wave activity observations in the outer belt during the Van Allen Probes era to compare 20 electron enhancement and 8 depletion events. Results indicate that the combined effect of magnetopause shadowing and outward diffusion driven by Pc5 waves is present in both groups of events. Furthermore, in the case of enhancement events, the synergy of enhanced seed population levels and chorus activity—due to the enhanced substorm activity—can effectively replenish the losses of relativistic electrons, while inward diffusion can further accelerate them.
On the Generation Mechanism of Electromagnetic Cyclotron Waves in the Solar Wind: Statistical Results from Wind Observations

Electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency are frequently observed in the solar wind, yet their generation mechanism is still an open question. Based on the Wind data from 2005−2015, this paper carries out a statistical study on the plasma characteristics associated with the occurrence of ECWs. The probability density distributions (PDDs) of proton temperature anisotropy (T⊥/T∥) and proton parallel beta (β∥) are investigated, where ⊥ and ∥ refer to perpendicular and parallel to the background magnetic field, respectively. The PDDs depend on solar wind types as well as wave polarizations, and those for ECWs with left-handed (LH) polarization exhibit considerable differences from the PDDs for ambient solar winds. The distributions of occurrence rates of LH ECWs in (β∥, T⊥/T∥) space show a tendency that the occurrence rates increase with proton temperature anisotropies. The β∥ with the maximum of occurrence rates is near 0.1 when T⊥/T∥ > 1, while it is around 1 when T⊥/T∥ < 1. The presence of alpha−proton differential flow with large kinetic energy corresponds to a much higher occurrence rate as well as the domination of LH polarization of ECWs. Based on these observations and existing theories, we propose that the proton cyclotron and parallel firehose instabilities with effects of alpha−proton differential flow are likely responsible for the local generation of LH ECWs in the solar wind. The generation mechanism of right-handed (RH) ECWs seems to be complicated and more discussions are needed in future research.
Clocking the Evolution of Post-starburst Galaxies: Methods and First Results

Detailed modeling of the recent star formation histories (SFHs) of post-starburst (or “E+A”) galaxies is impeded by the degeneracy between the time elapsed since the starburst ended (post-burst age), the fraction of stellar mass produced in the burst (burst strength), and the burst duration. To resolve this issue, we combine GALEX ultraviolet photometry, SDSS photometry and spectra, and new stellar population synthesis models to fit the SFHs of 532 post-starburst galaxies. In addition to an old stellar population and a recent starburst, 48% of the galaxies are best fit with a second recent burst. Lower stellar mass galaxies (log M⋆/M☉ < 10.5) are more likely to experience two recent bursts, and the fraction of their young stellar mass is more strongly anticorrelated with their total stellar mass. Applying our methodology to other, younger post-starburst samples, we identify likely progenitors to our sample and examine the evolutionary trends of molecular gas and dust content with post-burst age. We discover a significant (4σ) decline, with a 117–230 Myr characteristic depletion time, in the molecular gas to stellar mass fraction with the post-burst age. The implied rapid gas depletion rate of 2–150 M☉ yr−1 cannot be due to current star formation, given the upper limits on the current star formation rates in these post-starbursts. Nor are stellar winds or supernova feedback likely to explain this decline. Instead, the decline points to the expulsion or destruction of molecular gas in outflows, a possible smoking gun for active galactic nucleus feedback.
On the Homology of the Schur Complex

The theory of Schur complexes in a characteristic free setting has w x shown, since its appearance ABW , to be useful in the study of finite free resolutions of determinantal ideals. Its development has gone beyond the original goal and now we have a collection of very interesting problems on characteristic-free representaw x tion theory of the general linear group AB . As a result of this, all the efforts made to develop the theory have a representation theoretic flavor, w x and besides the results on acyclicity of Schur complexes given in ABW , there is not much else in the literature. In this paper we study the vanishing behavior of the homology of the Schur complexes L w, associl ated to a partition l and an R-linear map w : G a F between finitely generated free R-modules, where rank G s n F m s rank F and R is a commutative noetherian ring. In this sense Boffi has studied the homology w x m of L f , and L f , where f is a generic alternating map B . Ž1 . Žm.
Mott-insulator–to–superfluid transition in the Bose-Hubbard model: A strong-coupling approach

We present a strong-coupling expansion of the Bose-Hubbard model which describes both the superfluid and the Mott phases of ultracold bosonic atoms in an optical lattice. By performing two successive Hubbard-Stratonovich transformations of the intersite hopping term, we derive an effective action which provides a suitable starting point to study the strong-coupling limit of the Bose-Hubbard model. This action can be analyzed by taking into account Gaussian fluctuations about the mean-field approximation as in the Bogoliubov theory of the weakly interacting Bose gas. In the Mott phase, we reproduce results of previous mean-field theories and also calculate the momentum distribution function. In the superfluid phase, we find a gapless spectrum and compare our results with the Bogoliubov theory.
Interpretation of deep counts of radio sources

A new determination of the local radio luminosity function of galaxies allows it to be concluded that unevolving low-luminosity sources cannot account for the observed flattening of the normalized differential source counts below mJy levels. Nor can this feature be produced by the evolving populations that dominate the counts at higher flux densities. The local radio luminosities of spiral galaxies are too low to contribute significantly to the counts above 1 mJy, even in the presence of evolution consistent with the observational constraints; thus the blue galaxy population observed by Kron, Koo, and Windhorst (1985) up to greater than or equal to 10 mJy can hardly be identified with normal spiral galaxies. On the other hand, it is shown that evolving starburst/interacting galaxies can easily account for all the data available so far. The inferred evolution time scale (about 20-25 percent of the Hubble time) is within the expected range for gas consumption in starburst galaxies. 36 references.