Miracle-dz/UniFAR-FTUs huggingface dataset:
Statistical Properties of Paired Fixed Fields

The initial conditions of cosmological simulations are commonly drawn from a Gaussian ensemble. The limited number of modes inside simulations gives rise to sample variance: statistical fluctuations that limit the accuracy of the simulation predictions. Fixed fields offer an alternative initialization strategy; they have the same power spectrum as Gaussian fields but no intrinsic amplitude scatter. Paired fixed fields consist of two fixed fields with opposite phases that cancel phase correlations. We study the statistical properties of those fields for 19 different quantities at different redshifts through a large set of 600 N-body and 530 state-of-the-art magnetohydrodynamic simulations. We find that paired fixed simulations do not introduce a bias on any of the examined quantities. We quantify the statistical improvement brought by these simulations on different power spectra—matter, halos, cold dark matter, gas, stars, galaxies, and magnetic fields—finding that they can reduce their variance by factors as large as 106. We quantify the improvement achieved by fixing and by pairing, showing that sample variance can be highly suppressed by pairing after fixing. Paired fixed simulations do not change the scatter in quantities such as the probability distribution function or the halo, void, or stellar mass functions. We argue that procedures aiming at reducing the sample variance of those quantities are unlikely to work. Our results show that paired fixed simulations do not affect either mean relations or scatter of galaxy properties and suggest that the information embedded in one-point statistics is highly complementary to that in clustering.
The Direct Detection and Characterization of M-dwarf Planets Using Light Echoes

Exoplanets orbiting M-dwarf stars are a prime target in the search for life in the universe. M-dwarf stars are active, with powerful flares that could adversely impact prospects for life, though there are counter-arguments. Here, we turn flaring to advantage and describe ways in which it can be used to enhance the detectability of planets, in the absence of transits or a coronagraph, significantly expanding the accessible discovery and characterization space. Flares produce brief bursts of intense luminosity, after which the star dims. Due to the light travel time between the star and planet, the planet receives the high-intensity pulse, which it re-emits through scattering (a light echo) or intrinsic emission when the star is much fainter, thereby increasing the planet’s detectability. The planet’s light-echo emission can potentially be discriminated from that of the host star by means of a time delay, Doppler shift, spatial shift, and polarization, each of which can improve the contrast of the planet to the star. Scattered light can reveal the albedo spectrum of the planet to within a size scale factor, and is likely to be polarized. Intrinsic emission mechanisms include fluorescent pumping of multiple molecular hydrogen and neutral oxygen lines by intense Lyα and Lyβ flare emission, recombination radiation of ionized and photodissociated species, and atmospheric processes such as terrestrial upper atmosphere airglow and near-infrared hydroxyl emission. We discuss the feasibility of detecting light echoes and find that light echo detection is possible under favorable circumstances.
“Micro” Extrathyroidal Extension in Risk Stratification for Papillary Thyroid Carcinoma: Should It Be in the Intermediate-Risk or High-Risk Group? A Single-Center Retrospective Study

Introduction Currently, there is no consensus on the specific effect of Extrathyroidal Extension (ETE) on prognosis. The purpose of our study was to study the relationship between different states of ETE and its disease-free survival rate and to determine the basic standard of Micro ETE (tumor extends through capsule only) in risk stratification. Material and Methods We conducted a retrospective and single-center study that included the clinical data of all papillary thyroid carcinoma (PTC) patients with ETE in our hospital from 2013 to 2017 and followed them up after rigorous screening. According to ETE state, it is divided into four groups: Microscopic, Micro, Minimal, Macro. Kaplan–Meier method was used to calculate disease-free survival (DFS). Log-rank test was used to compare the differences between the groups and to polt the survival curves. P<0.05 was considered statistically significant. Micro ETE was included in different risk stratification subgroups and their DFS was compared. Results A total of 436 patients were included: Microscopic group N=50 (11.47%), Micro group N=74 (16.97%), Minimal group N=135 (30.96%), and Macro group N=177 (40.60%). The frequency of ETE was in strap muscles N=191, trachea N=114, laryngeal recurrent nerve N=92, and capsule N=74, etc. The 5-year DFS rate in Micro group was 95.3%, higher than that in Macro group (P<0.05). The 5-year DFS rate of Micro ETE was 90.0% in the intermediate-risk group and 84.9% in the high-risk group when Micro ETE was included in different risk stratification subgroups. Conclusion Micro ETE deserves more attention, has a batter prognosis than Macro ETE, and may have little effect on recurrence. It seems more appropriate to treat Micro ETE as the intermediate-risk group in risk stratification.
Information and computation: Classical and quantum aspects

Quantum theory has found a new field of application in the realm of information and computation during recent years. This paper reviews how quantum physics allows information coding in classically unexpected and subtle nonlocal ways, as well as information processing with an efficiency largely surpassing that of the present and foreseeable classical computers. Some notable aspects of classical and quantum information theory will be addressed here. Quantum teleportation, dense coding, and quantum cryptography are discussed as examples of the impact of quanta on the transmission of information. Quantum logic gates and quantum algorithms are also discussed as instances of the improvement made possible in information processing by a quantum computer. Finally the authors provide some examples of current experimental realizations for quantum computers and future prospects.
Highly damped quasinormal modes of Kerr black holes

Motivated by recent suggestions that highly damped black hole quasinormal modes (QNM's) may provide a link between classical general relativity and quantum gravity, we present an extensive computation of highly damped QNM's of Kerr black holes. We perform the computation using two independent numerical codes based on Leaver's continued fraction method. We do not limit our attention to gravitational modes, thus filling some gaps in the existing literature. As already observed by Berti and Kokkotas, the frequency of gravitational modes with $l=m=2$ tends to ${\ensuremath{\omega}}_{R}=2\ensuremath{\Omega},$ $\ensuremath{\Omega}$ being the angular velocity of the black hole horizon. We show that, if Hod's conjecture is valid, this asymptotic behavior is related to reversible black hole transformations. Other highly damped modes with $mg0$ that we computed do not show a similar behavior. The real part of modes with $l=2$ and $ml0$ seems to asymptotically approach a constant value ${\ensuremath{\omega}}_{R}\ensuremath{\simeq}\ensuremath{-}m\ensuremath{\varpi},$ $\ensuremath{\varpi}\ensuremath{\simeq}0.12$ being (almost) independent of a. For any perturbing field, trajectories in the complex plane of QNM's with $m=0$ show a spiraling behavior, similar to the one observed for Reissner-Nordstr\"om black holes. Finally, for any perturbing field, the asymptotic separation in the imaginary part of consecutive modes with $mg0$ is given by $2\ensuremath{\pi}{T}_{H}$ ${(T}_{H}$ being the black hole temperature). We conjecture that for all values of l and $mg0$ there is an infinity of modes tending to the critical frequency for superradiance $({\ensuremath{\omega}}_{R}=m)$ in the extremal limit. Finally, we study in some detail modes branching off the so-called ``algebraically special frequency'' of Schwarzschild black holes. For the first time we find numerically that QNM multiplets emerge from the algebraically special Schwarzschild modes, confirming a recent speculation.
Probing the Radio Loud/Quiet AGN dichotomy with quasar clustering

We investigate the clustering properties of 45441 radio-quiet quasars (RQQs) and 3493 radio-loud quasars (RLQs) drawn from a joint use of the Sloan Digital Sky Survey (SDSS) and Faint Images of the Radio Sky at 20 cm (FIRST) surveys in the range $0.3<z<2.3$. This large spectroscopic quasar sample allow us to investigate the clustering signal dependence on radio-loudness and black hole (BH) virial mass. We find that RLQs are clustered more strongly than RQQs in all the redshift bins considered. We find a real-space correlation length of $r_{0}=6. 59_{-0.24}^{+0.33}\,h^{-1}\,\textrm{Mpc}$ and $r_{0}=10. 95_{-1.58}^{+1.22}\,h^{-1}\,\textrm{Mpc}$ {\normalsize{}for} RQQs and RLQs, respectively, for the full redshift range. This implies that RLQs are found in more massive host haloes than RQQs in our samples, with mean host halo masses of $\sim4.9\times10^{13}\,h^{-1}\,M_{\odot}$ and $\sim1.9\times10^{12}\,h^{-1}\,M_{\odot}$, respectively. Comparison with clustering studies of different radio source samples indicates that this mass scale of $\gtrsim1\times10^{13}\,h^{-1}\,M_{\odot}$ is characteristic for the bright radio-population, which corresponds to the typical mass of galaxy groups and galaxy clusters. The similarity we find in correlation lengths and host halo masses for RLQs, radio galaxies and flat-spectrum radio quasars agrees with orientation-driven unification models. Additionally, the clustering signal shows a dependence on black hole (BH) mass, with the quasars powered by the most massive BHs clustering more strongly than quasars having less massive BHs. We suggest that the current virial BH mass estimates may be a valid BH proxies for studying quasar clustering. We compare our results to a previous theoretical model that assumes that quasar activity
‘The bread and butter of a difficult profession’: mentoring as a resource for teacher stress

ABSTRACT Teacher stress continues to threaten the stability of the U.S. teaching workforce, but teacher mentoring, an increasingly prevalent type of teacher support, may uniquely support teachers with their risk-for-stress. The current study investigated how teacher mentoring experiences differ based on vulnerability to stress and teacher experience level. Semi-structured focus groups were conducted and analysed using the Consensual Qualitative Research (CQR) method. Results include five emergent domains indicating that teachers viewed mentoring as overwhelmingly supportive of their instructional needs, regardless of their stress risk or experience level. New and experienced teachers also shared similar experiences regarding the social emotional support that mentoring can provide. However, differing trends emerged between risk-for-stress groups in their reports of mentoring qualities and challenges, which may signal the need for differentiating mentoring supports based on teacher stress levels.
Combined results on b-hadron production rates, lifetimes, oscillations and semileptonic decays

Combined results on b-hadron lifetimes, b-hadron production rates B{sub d}{sup 0}--Anti-B{sub d}{sup 0} and B{sub s}{sup 0}--Anti-B{sub s}{sup 0} oscillations, the decay width difference between the mass eigenstates of the B{sub s}{sup 0}--Anti-B{sub s}{sup 0} system, and the values of the CKM matrix elements {vert_bar}V{sub cb}{vert_bar} and {vert_bar}V{sub ub}{vert_bar} are obtained from published and preliminary measurements available in Summer 99 from the ALEPH, CDF, DELPHI, L3, OPAL and SLD Collaborations.
Modelling redshift space distortion in the post-reionization H i 21-cm power spectrum

The post-reionization ${\rm HI}$ 21-cm signal is an excellent candidate for precision cosmology, this however requires accurate modelling of the expected signal. Sarkar et al. (2016) have simulated the real space ${\rm HI}$ 21-cm signal, and have modelled the ${\rm HI}$ power spectrum as $P_{{\rm HI}}(k)=b^2 P(k)$ where $P(k)$ is the dark matter power spectrum and $b(k)$ is a (possibly complex) scale dependent bias for which fitting formulas have been provided. This paper extends these simulations to incorporate redshift space distortion and predict the expected redshift space ${\rm HI}$ 21-cm power spectrum $P^s_{{\rm HI}}(k_{\perp},k_{\parallel})$ using two different prescriptions for the ${\rm HI}$ distributions and peculiar velocities. We model $P^s_{{\rm HI}}(k_{\perp},k_{\parallel})$ assuming that it is the product of $P_{{\rm HI}}(k)=b^2 P(k)$ with a Kaiser enhancement term and a Finger of God (FoG) damping which has $\sigma_p$ the pair velocity dispersion as a free parameter. Considering several possibilities for the bias and the damping profile, we find that the models with a scale dependent bias and a Lorentzian damping profile best fit the simulated $P^s_{{\rm HI}}(k_{\perp},k_{\parallel})$ over the entire range $1 \le z \le 6$. The best fit value of $\sigma_p$ falls approximately as $(1+z)^{-m}$ with $m=2$ and $1.2$ respectively for the two different prescriptions. The model predictions are consistent with the simulations for $k < 0.3 \, {\rm Mpc}^{-1}$ over the entire $z$ range for the monopole $P^s_0(k)$, and at $z \le 3$ for the quadrupole $P^s_2(k)$. At $z \ge 4$ the models underpredict $P^s_2(k)$ at large $k$, and the fit is restricted to $k < 0.15 \, {\rm Mpc}^{-1}$.
Oort spike comets with large perihelion distances

The complete sample of large-perihelion nearly-parabolic comets discovered during the period 1901-2010 is studied starting from their orbit determination. Next, an orbital evolution that includes three perihelion passages (previous-observed-next) is investigated where a full model of Galactic perturbations and perturbations from passing stars have been incorporated. We show that the distribution of planetary perturbations suffered by actual large-perihelion comets during their passage through the Solar system has a deep, unexpected minimum around zero which indicates a lack of "almost unperturbed" comets. By a series of simulations we show that this deep well is moderately resistant to some diffusion of orbital elements of analysed comets. It seems reasonable to state that the observed stream of these large-perihelion comets experienced a series of specific planetary configurations when passing through the planetary zone. An analysis of the past dynamics of these comets clearly shows that dynamically new comets may appear only when their original semimajor axes are greater than 20 000 au. However, only for semimajor axes longer than 40 000 au dynamically old comets are completely not present. We demonstrated that the observed $1/a_{\rm ori}$ distribution exhibits a local minimum separating dynamically new from dynamically old comets. Long-term dynamical studies reveal a large variety of orbital behaviour. Several interesting examples of action of passing stars are also described, in particular the impact of Gliese 710 which will pass close to the Sun in the future. However, none of the obtained stellar perturbations is sufficient to change the dynamical status of analysed comets.
Topological Charge of U(1) Instantons

Non-singular instantons are shown to exist on noncommutative R^4 even with a U(1) gauge group. Their existence is primarily due to the noncommutativity of the space. The relation between U(1) instantons on noncommutative R^4 and the projection operators acting on the representation space of the noncommutative coordinates is reviewed. The integer number of instantons on the noncommutative R^4 can be understood as the winding number of the U(1) gauge field as well as the dimension of the projection on the representation space.
Entanglement of Quantum Evolutions

The notion of entanglement can be naturally extended from quantum-states to the level of general quantum evolutions. This is achieved by considering multi-partite unitary transformations as elements of a multi-partite Hilbert space and then extended to general quantum operations. We show some connection between this entanglement and the entangling capabilities of the quantum evolution.
Skyrmion clusters from Bloch lines in ferromagnetic films

Conditions under which various skyrmion objects emerge in experiments on thin magnetic films remain largely unexplained. We investigate numerically centrosymmetric spin lattices in films of finite thickness with ferromagnetic exchange, magnetic anisotropy, and dipole-dipole interaction. Evolution of labyrinth domains into compact topological structures on application of the magnetic field is found to be governed by the configuration of Bloch lines inside domain walls. Depending on the combination of Bloch lines, the magnetic domains evolve into individual skyrmions, biskyrmions, or more complex topological objects. While the geometry of such objects is sensitive to the parameters, their topological charge is uniquely determined by the topological charge of Bloch lines inside the magnetic domain from which the object emerges.
Quasi-periodic Counter-propagating Fast Magnetosonic Wave Trains from Neighboring Flares: SDO/AIA Observations and 3D MHD Modeling

Since their discovery by the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) in the extreme ultraviolet, rapid (phase speeds of ∼1000 km s−1), quasi-periodic, fast-mode propagating (QFP) wave trains have been observed accompanying many solar flares. They typically propagate in funnel-like structures associated with the expanding magnetic field topology of the active regions (ARs). The waves provide information on the associated flare pulsations and the magnetic structure through coronal seismology (CS). The reported waves usually originate from a single localized source associated with the flare. Here we report the first detection of counter-propagating QFPs associated with two neighboring flares on 2013 May 22, apparently connected by large-scale, trans-equatorial coronal loops. We present the first results of a 3D MHD model of counter-propagating QFPs in an idealized bipolar AR. We investigate the excitation, propagation, nonlinearity, and interaction of the counter-propagating waves for a range of key model parameters, such as the properties of the sources and the background magnetic structure. In addition to QFPs, we also find evidence of trapped fast- (kink) and slow-mode waves associated with the event. We apply CS to determine the magnetic field strength in an oscillating loop during the event. Our model results are in qualitative agreement with the AIA-observed counter-propagating waves and used to identify the various MHD wave modes associated with the observed event, providing insights into their linear and nonlinear interactions. Our observations provide the first direct evidence of counter-propagating fast magnetosonic waves that can potentially lead to turbulent cascade and carry significant energy flux for coronal heating in low-corona magnetic structures.
On Characterization of Second-Order Asymptotic Optimality Under Asymmetric Loss Functions: Loss Coefficient Vector and Admissibility

Our main concern is on second-order asymptotic optimality theory of estimators under asymmetric loss functions. It is shown that the problem of comparing two estimators under asymmetric loss functions is completely characterized by the pair of three qualities characteristic to the loss function, which is called the loss coefficient vector. The loss coefficient vector is calculated for some familiar asymmetric loss function, including the linear loss and the LINEX loss. Furthermore, we discuss the second-order admissibility of estimators. A sufficient and necessary condition for an estimator to be second-order admissible is given and a method to construct some second-order admissible estimators is proposed.
Ruling out 3 keV warm dark matter using 21 cm EDGES data

Weakly interacting cold dark matter (CDM) particles, which are otherwise extremely successful in explaining various cosmological observations, exhibit a number of problems on small scales. One possible way of solving these problems is to invoke (so-called) warm dark matter (WDM) particles with masses $m_x \sim$ keV. Since the formation of structure is delayed in such WDM models, it is natural to expect that they can be constrained using observations related to the first stars, e.g., the 21 cm signal from cosmic dawn. In this work, we use a detailed galaxy formation model, Delphi, to calculate the 21 cm signal at high-redshifts and compare this to the recent EDGES observations. We find that while CDM and 5 keV WDM models can obtain a 21 cm signal within the observed redshift range, reproducing the amplitude of the observations requires the introduction of an excess radio background. On the other hand, WDM models with $m_x \leq 3$ keV can be ruled out since they are unable to match either the redshift range or the amplitude of the EDGES signal, irrespective of the parameters used. Comparable to values obtained from the low-redshift Lyman Alpha forest, our results extend constraints on the WDM particle to an era inaccessible by any other means; additional forthcoming 21 cm data from the era of cosmic dawn will be crucial in refining such constraints.
Tensor non-gaussianities from non-minimal coupling to the inflaton

Tensor non-Gaussianity represents an important future probe of the physics of inflation. Inspired by recent works, we elaborate further on the possibility of significant primordial tensor non-Gaussianities sourced by extra fields during inflation. Unitarity constraints limit the impact of extra (spinning) particle content by means of a lower bound on the corresponding mass spectrum. For spin-2 particles, this takes the form of the well-known Higuchi bound. Massive (m≳ H) particles will typically decay during inflation unless they are non-minimally coupled to the inflaton sector: the inflating field “lifts” the dynamics of the extra field(s), effectively getting around the limits imposed by unitarity. There exist several models that realize such a mechanism, but we focus here on the set-up of [1] where, through an EFT approach, one is able to capture the essential features common to an entire class of theories. In the presence of an extra massive spin-2 particle, the interactions in the tensor sector mimic very closely those in the scalar sector of quasi-single-field inflationary models. We calculate the tensor bispectrum in different configurations and extract its dependence on the extra tensor sound speed. We show in detail how one may obtain significant tensor non-Gaussianities whose shape-function interpolates between local and equilateral, depending on the mass of the extra field. We also estimate the LISA response functions to a tensor bispectrum supporting the intermediate-type shapes we find.
Information exchange through secret vertical contracts

We study a common agency problem in which two downstream firms, who are local monopolists and receive private demand signals, offer secret menus of two-part tariff contracts to their common supplier. While direct communication is not possible, they may still exchange their information through signal-contingent menus of vertical contracts. We show that a perfect Bayesian equilibrium exists in which information is transmitted, and downstream firms obtain nearly the first-best industry surplus. The use of both fixed charges and slotting fees is necessary for such a result. Our analysis provides a novel explanation for the use of slotting fees in vertical contracting based on its value as an information transmission device.