Miracle-dz/UniFAR-FTUs huggingface dataset:
A formula for crossing probabilities of critical systems inside polygons

In this article, we use our results from Flores and Kleban (2015 Commun. Math. Phys. 333 389–434, 2015 Commun. Math. Phys. 333 435–81, 2015 Commun. Math. Phys. 333 597–667, 2015 Commun. Math. Phys. 333 669–715) to generalize known formulas for crossing probabilities. Prior crossing results date back to Cardy’s prediction of a formula for the probability that a percolation cluster in two dimensions connects the left and right sides of a rectangle at the percolation critical point in the continuum limit (Cardy 1992 J. Phys. A: Math. Gen. 25 L201–6). Here, we predict a new formula for crossing probabilities of a continuum limit loop-gas model on a planar lattice inside a 2N-sided polygon. In this model, boundary loops exit and then re-enter the polygon through its vertices, with exactly one loop passing once through each vertex, and these loops join the vertices pairwise in some specified connectivity through the polygon’s exterior. The boundary loops also connect the vertices through the interior, which we regard as a crossing event. For particular values of the loop fugacity, this formula specializes to FK cluster (resp. spin cluster) crossing probabilities of a critical Q-state random cluster (resp. Potts) model on a lattice inside the polygon in the continuum limit. This includes critical percolation as the Q = 1 random cluster model. These latter crossing probabilities are conditioned on a particular side-alternating free/fixed (resp. fluctuating/fixed) boundary condition on the polygon’s perimeter, related to how the boundary loops join the polygon’s vertices pairwise through the polygon’s exterior in the associated loop-gas model. For Q∈{2,3,4}, we compare our predictions of these random cluster (resp. Potts) model crossing probabilities in a rectangle (N = 2) and in a hexagon (N = 3) with high-precision computer simulation measurements. We find that the measurements agree with our predictions very well for Q∈{2,3} and reasonably well if Q = 4.
The EDGE–CALIFA survey: validating stellar dynamical mass models with CO kinematics

Deriving circular velocities of galaxies from stellar kinematics can provide an estimate of their total dynamical mass, provided a contribution from the velocity dispersion of the stars is taken into account. Molecular gas (e.g., CO) on the other hand, is a dynamically cold tracer and hence acts as an independent circular velocity estimate without needing such a correction. In this paper we test the underlying assumptions of three commonly used dynamical models, deriving circular velocities from stellar kinematics of 54 galaxies (S0-Sd) that have observations of both stellar kinematics from the CALIFA survey, and CO kinematics from the EDGE survey. We test the Asymmetric Drift Correction (ADC) method, as well as Jeans, and Schwarzschild models. The three methods each reproduce the CO circular velocity at 1Re to within 10%. All three methods show larger scatter (up to 20%) in the inner regions (R < 0.4Re) which may be due to an increasingly spherical mass distribution (which is not captured by the thin disk assumption in ADC), or non-constant stellar M/L ratios (for both the JAM and Schwarzschild models). This homogeneous analysis of stellar and gaseous kinematics validates that all three models can recover Mdyn at 1Re to better than 20%, but users should be mindful of scatter in the inner regions where some assumptions may break down.
Relaxing the parity conditions of asymptotically flat gravity

Four-dimensional asymptotically flat spacetimes at spatial infinity are defined from first principles without imposing parity conditions or restrictions on the Weyl tensor. The Einstein–Hilbert action is shown to be a correct variational principle when it is supplemented by an anomalous counterterm which breaks asymptotic translation, supertranslation and logarithmic translation invariance. Poincaré transformations as well as supertranslations and logarithmic translations are associated with finite and conserved charges which represent the asymptotic symmetry group. Lorentz charges as well as logarithmic translations transform anomalously under a change of regulator. Lorentz charges are generally nonlinear functionals of the asymptotic fields but reduce to well-known linear expressions when parity conditions hold. We also define a covariant phase space of asymptotically flat spacetimes with parity conditions but without restrictions on the Weyl tensor. In this phase space, the anomaly plays classically no dynamical role. Supertranslations are pure gauge and the asymptotic symmetry group is the expected Poincaré group.
THE BLACK HOLE MASS–STELLAR VELOCITY DISPERSION RELATIONSHIP FOR QUASARS IN THE SLOAN DIGITAL SKY SURVEY DATA RELEASE 7

We assess evolution in the MBH–σ* relationship for quasars in the Sloan Digital Sky Survey Data Release 7 for the redshift range 0.1 < z < 1.2. We estimate the black hole mass, MBH, using the “photoionization method,” with the broad Hβ or Mg ii emission line and the quasar continuum luminosity. For the stellar velocity dispersion, we use the narrow [O iii] or [O ii] emission line as a surrogate. This study is a follow-up to an earlier study in which we investigated evolution in the MBH–σ* relationship in quasars from Data Release 3. The greatly increased number of quasars in our new sample has allowed us to break our lower-redshift subsample into black hole mass bins and probe the MBH–σ* relationship for constant black hole mass. The MBH–σ* relationship for the highest-mass (MBH > 109.0 M☉) and lowest-mass (MBH < 107.5 M☉) black holes appears to evolve significantly; however, most or all of this apparent evolution can be accounted for by various observational biases due to intrinsic scatter in the relationship and to uncertainties in observed quantities. The MBH–σ* relationship for black holes in the middle mass range (107.5 < MBH < 109.0 M☉) shows minimal change with redshift. The overall results suggest a limit of ±0.2 dex on any evolution in the MBH–σ* relationship for quasars out to z ≈ 1 compared with the relationship observed in the local universe. Intrinsic scatter may also provide a plausible way to reconcile the wide range of results of several different studies of the black hole–galaxy relationships.
HD 98800: a most unusual debris disc

The dynamics of planetesimals in the circumbinary debris disc of the quadruple star system HD 98800 are investigated. Evolving a spherical shell of test particles from a million years ago to the present day indicates that both coplanar and retrograde warped discs could exist, as well as a high-inclination halo of material. Significant gaps are seen in the discs, as well as unexpected regions of stability due to the retrograde nature of the stellar orbits. Despite a viewing angle almost perpendicular to the direction of the warp of the planetesimal disc it is still intersected by the line of sight for eccentricities of the outer orbit of 0.5 or less.
What Happens When Ratings Shopping is Visible? Evidence from Unaccepted Ratings Disclosure *

: Ratings shopping is a well-documented cause for ratings inflation by credit rating agencies (CRAs). But the extent of ratings shopping by issuers, and the CRA’s propensity to cater to the demand of inflated ratings by issuers is unobservable, making it difficult for market participants to undo it. In this paper, we exploit a unique setting in India, a regulation that requires CRAs to disclose ratings unaccepted by issuers. We ask whether these disclosures influence ratings shopping, and consequently ratings inflation. We find that the disclosure requirements result in a decline in ratings shopping, defined in a narrow form wherein issuers seek ratings from multiple CRAs and then strategically decide whether to report their ratings. We also find that, in the post-regulation period, issuers are more likely to approach a smaller CRA; and that this leads to an unintended increase in ratings shopping in a broad form, wherein issuers strategically choose the CRAs that will give them a better rating. These results are consistent with the view that the enhanced disclosure requirements produced unintended effects, and that they did not achieve their objectives of reducing shopping and ratings inflation. Wang seminar MIT Asia Conference, NSE-NYU Conference, University of Western Australia, ISB Accounting Conference, CAFRAL for their helpful comments and suggestions. We acknowledge the financial of detailed rating criteria, including on default recognition, and explaining the use of financial ratios; disclosure of eligibility requirements of auditors for conducting internal audits of CRAs; laying out the roles and responsibilities of the rating analysts; policies regarding non-cooperation by the issuer; standardization of press release after assigning a rating; publishing rating history of all instruments of the issuer rated by CRA in the past three years and withdrawn ratings. Our results suggest that the pressure on CRAs to generate business has a greater impact on rating quality than the disciplining role of disclosures. We argue that “shopping” can be viewed in a narrow sense or a broad sense. Our findings indicate that SEBI’s additional disclosure requirement has deterred shopping in the narrow sense, by which we mean obtaining a rating and then strategically deciding whether to accept it. But if we regard ratings shopping in a broader sense, we see that issuers can continue to shop for ratings by other means, for example, by discerning through informal conversations what rating a particular CRA is likely to give and choosing CRAs more likely to provide better ratings.
The analytic conformal compactification of the Schwarzschild spacetime

Among the coordinates used to construct a conformal compactification of the Schwarzschild spacetime, none of them simultaneously extend smoothly both through an event horizon and beyond null infinity. To construct such coordinates, instead of starting with the Kruskal–Szekeres coordinates, we assume direct analytic transformation between Schwarzschild and compactified coordinates and determine their behavior on the event horizon and at null infinity. We then propose an example of such coordinates and illustrate the way they cover the conformally extended Schwarzschild spacetime as well as their suitability for numerical applications.
THE ORBIT OF THE STAR S2 AROUND SGR A* FROM VERY LARGE TELESCOPE AND KECK DATA

Two recent papers (Ghez et al. 2008; Gillessen et al. 2009) have estimated the mass of and the distance to the massive black hole (MBH) in the center of the Milky Way using stellar orbits. The two astrometric data sets are independent and yielded consistent results, even though the measured positions do not match when simply overplotting the two sets. In this Letter, we show that the two sets can be brought to excellent agreement with each other when we allow for a small offset in the definition of the reference frame of the two data sets. The required offsets in the coordinates and velocities of the origin of the reference frames are consistent with the uncertainties given in Ghez et al. The so-combined data set allows for a moderate improvement of the statistical errors of the mass of and the distance to Sgr A*, but the overall accuracies of these numbers are dominated by systematic errors and the long-term calibration of the reference frame. We obtain R0 = 8.28 ± 0.15|stat ± 0.29|sys kpc and MMBH = 4.30 ± 0.20|stat ± 0.30|sys × 106 M☉ as best estimates from a multi-star fit.
Precocity Threat

As the modern workforce becomes more age diverse and career ascension less contingent upon seniority, workers interact regularly with professionals younger than them who enjoy a higher level of occupational status than them (e.g., younger bosses, department superstars). Researchers have long theorized that these age counter-normative relationships are fraught with unique interpersonal challenges (i.e., communication, bonding, power struggles) that hinder job performance. Despite this theoretical consensus however, evidence supporting this claim has been mixed. Departing from prior relational perspectives, we build on social comparison theories and envy to propose that exposure to younger, higher status workers triggers precocity threat: an unfavorable self-reflective process that reduces one’s aspiration to reach a similar professional outcome and undercut one’s career investment, ultimately denting job performance. Using a host of methods to establish causal inference, we find consistent evidence of precocity threat across a longitudinal, archival U.S. professional sport dataset (N = 5,093), a matched quasi-experiment at a Latin American financial institution (N = 2,573 and N = 2,842), and a pre-registered online experiment with a diverse sample of U.K.-based workers (N = 1,112). These findings provide the first robust causal evidence of the negative effects of age counter-normative interactions at the workplace, show the ubiquity of precocity threat in contemporary organizations, and introduce a self-reflective mechanism that helps clarify when the negative relational processes theorized in prior work might take effect. Precocity threat illustrates the subtle ways in which the new age landscape of modern workplaces shapes the everyday productivity of today’s workforce.
Evaluating GANs using Efﬁcient Real-World Estimate (Project Report - CSC2515)

Evaluation of generative models is a crucial task, and many metrics today ignore the reverse KL divergence component due to an existing difﬁculty in obtaining the real-world density estimate p r from the limited number of samples available. In this work, we propose a MCMC sampling method using Metropolis-Hastings algorithm for obtaining samples from p r as learned by the discriminator D of a GAN, using samples from the generator G . We improve upon an existing rejection sampling approach with respect to a higher acceptance percentage and less samples rejected around the modes. We show how this can be used to evaluate a metric containing a reverse KLD component, rather than adhering to a log-likelihood metric, which seems unfair for models like GANs which intend to minimize the Jenson-Shannon divergence in their loss function. This method can also be used for monitoring how well the generator has been trained with respect to the real-world estimate of the discriminator.
Phase-coherent transport in catalyst-free vapor phase deposited Bi2Se3 crystals

Free-standing Bi$_2$Se$_3$ single crystal flakes of variable thickness are grown using a catalyst-free vapor-solid synthesis and are subsequently transferred onto a clean Si$^{++}$/SiO$_2$ substrate where the flakes are contacted in Hall bar geometry. Low temperature magneto-resistance measurements are presented which show a linear magneto-resistance for high magnetic fields and weak anti-localization (WAL) at low fields. Despite an overall strong charge carrier tunability for thinner devices, we find that electron transport is dominated by bulk contributions for all devices. Phase coherence lengths $\l_\phi$ as extracted from WAL measurements increase linearly with increasing electron density exceeding $1 \mu $m at 1.7 K. While $\l_\phi$ is in qualitative agreement with electron electron interaction-induced dephasing, we find that spin flip scattering processes limit $\l_\phi$ at low temperatures.
Relative Feedback Increases Disparities in Eﬀort and Performance in Crowdsourcing Contests: Evidence from a Quasi-Experiment on Topcoder

Rankings and leaderboards are often used in crowdsourcing contests and online communities to motivate individual contributions but feedback based on social comparison can also have negative eﬀects. Here, we study the unequal eﬀects of such feedback on individual eﬀort and performance for individuals of diﬀerent ability. We hypothesize that the eﬀects of social comparison diﬀer for top performers and bottom performers in a way that the inequality between the two increases. We use a quasi-experimental design to test our predictions with data from Topcoder, a large online crowdsourcing platform that publishes computer programming contests. We ﬁnd that in contests where the submitted code is evaluated against others’ submissions, rather than using an absolute scale, top performers increase their eﬀort while bottom performers decrease it. As a result, relative scoring leads to better outcomes for those at the top but lower engagement for bottom performers. Our ﬁndings expose an important but overlooked drawback from using gamiﬁed competitions, rankings, and relative evaluations, with potential implications for crowdsourcing markets, online learning environments, online communities, and organizations in general.
Rubber friction on (apparently) smooth lubricated surfaces

We study rubber sliding friction on hard lubricated surfaces. We show that even if the hard surface appears smooth to the naked eye, it may exhibit short-wavelength roughness, which may make the dominant contribution to rubber friction. That is, the observed sliding friction is mainly due to the viscoelastic deformations of the rubber by the counterface surface asperities. The results presented are of great importance for rubber sealing and other rubber applications involving (apparently) smooth surfaces.
Risk Prediction of Opioid Use Disorder (OUD) using Electronic Health Records

The opioid epidemic has emerged as a public health crisis, attracting increasing nationwide attention. Electronic health records (EHRs) provide rich resources to investigate and predict the risk of opioid use disorder (OUD) in real-world settings due to its diversity of data types and wide range of information. In this dissertation, I conducted three studies to investigate the association between OUD and different f actors i n E HR, i ncluding d emographics, c omorbidity, laboratory test results, medications, and opioid prescription, and develop predictive models to predict OUD risk using features from EHR data. In Manuscript 1, we used penalized logistic regression models to predict OUD in the emergency department in order to handle the large number of predictors and imbalanced classes for OUD in EHR data. We presented the prediction performance of Lasso logistic regression, Firth logistic regression, Firth logistic regression with intercept-correction (FLIC), and Firth logistic regression with added covariate (FLAC) and show how physical and mental comorbidity contributed to the risk of opioid misuse in the emergency department. In Manuscript 2, a shared parameter joint model for longitudinal and timeto-event data was built to investigate the association between longitudinal opioid prescription dosages and time to OUD onset after patients’ first opioid prescription from emergency department. Results from the models suggested a weak positive association between longitudinal opioid prescription dosage and the OUD onset. We also tested how the shared parameter model can handle data missing at random in a simulation study shown in Appendix B. In Manuscript 3, we proposed a conditional Gated Recurrent Unit with decay rate (GRU-D) model to predict the risk of opioid dependence and abuse using both static features, like demographics and disease history, and temporal features, such as laboratory test results during the entire visit. The GRU-D model allows us to capture the patterns of temporal features even though the measurements in EHR are collected irregularly or missing due to practical issues. We presented and discussed the predictive performance of our proposed conditional GRU-D with a GRU-D model with only temporal features and a GRU-D model with static features added at first time step. In addition, we investigated the feature importance using Leave-One-Covariate-Out (LOCO) approach. The top 15 most important predictors was presented, covering static features, such as insurance type, race, anxiety history, and also temporal features, such as blood test results, and medication use.
Evidence for a Cool Disk and Inhomogeneous Coronae from Wide-Band Temporal Spectroscopy of Cygnus X-1 with Suzaku

Unified X-ray spectral and timing studies of Cygnus X-1 in the low/hard and hard intermediate state were conducted in a model-independent manner, using broadband Suzaku data acquired on 25 occasions from 2005 to 2009 with a total exposure of ~ 450 ks. The unabsorbed 0.1--500 keV source luminosity changed over 0.8--2.8% of the Eddington limit for 14.8 solar masses. Variations on short (1--2 seconds) and long (days to months) time scales require at least three separate components: a constant component localized below ~2 keV, a broad soft one dominating in the 2--10 keV range, and a hard one mostly seen in 10--300 keV range. In view of the truncated disk/hot inner flow picture, these are respectively interpreted as emission from the truncated cool disk, a soft Compton component, and a hard Compton component. Long-term spectral evolution can be produced by the constant disk increasing in temperature and luminosity as the truncation radius decreases. The soft Compton component likewise increases, but the hard Compton does not, so that the spectrum in the hard intermediate state is dominated by the soft Compton component; on the other hand, the hard Compton component dominates the spectrum in the dim low/hard state, probably associated with a variable soft emission providing seed photons for the Comptonization.
Residents Perceptions of the Economic Impacts of Hosting Mega Sports Events: A Cross-Sectional Study of Host Cities of AFCON 2022 in Cameroon

: Economic incentives often constitute the thrust of galvanizing local community support for mega sports events. The purpose of this study was to explore the perceptions of residents of the AFCON 2022 host cities on the economic impacts of the mega sports event on their lives and the city. The cross-sectional study employed a quantitative research paradigm through the use of a questionnaire in collecting 1683 duly completed responses from residents of the five AFCON 2022 host cities. Participants were randomly selected among residents who expressed willingness to take part in the study and descriptive and exploratory data analysis was performed on the data. The analysis revealed that the respondents place great importance on the security situation in the country and perceive economic benefits to be related to the security situation. It is therefore concluded that to derive maximum economic benefits from AFCON 2022, the government needed to have found a speedy way to resolve the ongoing armed conflict. Practical and policy implications are discussed, particularly the development of inclusive policies that would bring more women into the economic mainstream and the combating of poverty with systematic policy instruments, rather than with a once-off event such as the AFCON mega event.