Miracle-dz/UniFAR-FTUs huggingface dataset:
A Retrospective Approximation Approach for Smooth Stochastic Optimization

Stochastic Gradient (SG) is the defacto iterative technique to solve stochastic optimization (SO) problems with a smooth (non-convex) objective $f$ and a stochastic first-order oracle. SG's attractiveness is due in part to its simplicity of executing a single step along the negative subsampled gradient direction to update the incumbent iterate. In this paper, we question SG's choice of executing a single step as opposed to multiple steps between subsample updates. Our investigation leads naturally to generalizing SG into Retrospective Approximation (RA) where, during each iteration, a"deterministic solver"executes possibly multiple steps on a subsampled deterministic problem and stops when further solving is deemed unnecessary from the standpoint of statistical efficiency. RA thus rigorizes what is appealing for implementation -- during each iteration,"plug in"a solver, e.g., L-BFGS line search or Newton-CG, as is, and solve only to the extent necessary. We develop a complete theory using relative error of the observed gradients as the principal object, demonstrating that almost sure and $L_1$ consistency of RA are preserved under especially weak conditions when sample sizes are increased at appropriate rates. We also characterize the iteration and oracle complexity (for linear and sub-linear solvers) of RA, and identify a practical termination criterion leading to optimal complexity rates. To subsume non-convex $f$, we present a certain"random central limit theorem"that incorporates the effect of curvature across all first-order critical points, demonstrating that the asymptotic behavior is described by a certain mixture of normals. The message from our numerical experiments is that the ability of RA to incorporate existing second-order deterministic solvers in a strategic manner might be important from the standpoint of dispensing with hyper-parameter tuning.
Randomization-based joint central limit theorem and efficient covariate adjustment in randomized block 2K factorial experiments

Randomized block factorial experiments are widely used in industrial engineering, clinical trials, and social science. Researchers often use a linear model and analysis of covariance to analyze experimental results; however, limited studies have addressed the validity and robustness of the resulting inferences because assumptions for a linear model might not be justified by randomization in randomized block factorial experiments. In this paper, we establish a new finite population joint central limit theorem for usual (unadjusted) factorial effect estimators in randomized block $2^K$ factorial experiments. Our theorem is obtained under a randomization-based inference framework, making use of an extension of the vector form of the Wald--Wolfowitz--Hoeffding theorem for a linear rank statistic. It is robust to model misspecification, numbers of blocks, block sizes, and propensity scores across blocks. To improve the estimation and inference efficiency, we propose four covariate adjustment methods. We show that under mild conditions, the resulting covariate-adjusted factorial effect estimators are consistent, jointly asymptotically normal, and generally more efficient than the unadjusted estimator. In addition, we propose Neyman-type conservative estimators for the asymptotic covariances to facilitate valid inferences. Simulation studies and a clinical trial data analysis demonstrate the benefits of the covariate adjustment methods.
Fully constrained, high-resolution shock-capturing, formulation of the Einstein-fluid equations in 
2+1
 dimensions

Four components of the axisymmetric Einstein equations in 2+1 dimensions with negative cosmological constant can be written as ∇aM = . and ∇aJ = . , where the dots stand for stress-energy terms, and M and J are scalars. In vacuum, they reduce to the constant mass and angular momentum parameters of the BTZ solution of the same name. The integrability conditions for the Einstein equations give rise to two conserved stress-energy currents ∇aj (M) = 0 and ∇aj (J) = 0. The angular momentum current is just the Noether current due to axisymmetry, but the mass current is unexpected in the presence of rotation. The conserved quantity M exists in all dimensions in spherical symmetry, known as the Misner-Sharp, Hawking or Kodama mass, but in 2+1 dimensions M exists also in axisymmetry, even with rotation. We use M and J to give a fully constrained formulation of the axisymmetric Einstein equations in 2 + 1 dimensions, where the Einstein equations are solved by explicit integration from the centre along time slices. We use the two conserved matter currents in the construction of a high-resolution shock-capturing formulation of the Einstein-perfect fluid system, in which M and J momentum are then exactly conserved by construction. We demonstrate convergence of the code in the test cases of generic dispersion and collapse and stable and unstable rotating stars.
ANONYMOUS ASSERTIONS

Abstract This paper addresses how the anonymity of an assertion affects the epistemological dimension of its production by speakers, and its reception by hearers. After arguing that anonymity does have implications in both respects, I go on to argue that at least some of these implications derive from a warranted diminishment in speakers' and hearers' expectations of one another when there are few mechanisms for enforcing the responsibilities attendant to speech. As a result, I argue, anonymous assertions do not carry the same ‘promise’ of the speaker's relevant epistemic authoritativeness that ordinary assertions do. If this is correct, the phenomenon of anonymity provides us with a lesson regarding ordinary assertions: their aptness for engendering belief in others, and so for communicating knowledge, depends in general on the very publicness of the act of assertion itself.
Mean Field Contest with Singularity

We formulate a mean field game where each player stops a privately observed Brownian motion with absorption. Players are ranked according to their level of stopping and rewarded as a function of their relative rank. There is a unique mean field equilibrium, and it is shown to be the limit of associated n-player games. Conversely, the mean field strategy induces n-player ε-Nash equilibria for any continuous reward function—but not for discontinuous ones. In a second part, we study the problem of a principal who can choose how to distribute a reward budget over the ranks and aims to maximize the performance of the median player. The optimal reward design (contract) is found in closed form, complementing the merely partial results available in the n-player case. We then analyze the quality of the mean field design when used as a proxy for the optimizer in the n-player game. Surprisingly, the quality deteriorates dramatically as n grows. We explain this with an asymptotic singularity in the induced n-player equilibrium distributions.
Pebble Trapping in Vortices: Three-dimensional Simulations

Disk vortices have been heralded as promising routes for planet formation due to their ability to trap significant amounts of pebbles. While the gas motions and trapping properties of two-dimensional vortices have been studied in enough detail in the literature, pebble trapping in three dimensions has received less attention, due to the higher computational demand. Here we use the Pencil Code to study 3D vortices generated by convective overstability and the trapping of solids within them. The gas is unstratified whereas the pebbles settle to the midplane due to vertical gravity. We find that for pebbles of normalized friction times of St=0.05 and St=1 , and dust-to-gas ratio ε=0.01 , the vortex column in the midplane is strongly perturbed. Yet when the initial dust-to-gas ratio is decreased the vortices remain stable and function as efficient pebble traps. Streaming instability is triggered even for the lowest dust-to-gas ratio ( ε0=10−4 ) and smallest pebble sizes ( St=0.05 ) we assumed, showing a path for planetesimal formation in vortex cores from even extremely subsolar metallicity. To estimate if the reached overdensities can be held together solely by their own gravity we estimate the Roche density at different radii. Depending on disk model and radial location of the pebble clump we do reach concentrations higher than the Roche density. We infer that if self-gravity was included for the pebbles then gravitational collapse would likely occur.
Spatial- and Range- ISLR Trade-Off in MIMO Radar Via Waveform Correlation Optimization

This paper aims to design a set of transmit waveforms in cognitive colocated Multi-Input Multi-Output (MIMO) radar systems considering the simultaneous minimization of spatial- and the range- Integrated Sidelobe Level Ratio (ISLR). The design problem is formulated as a bi-objective Pareto optimization under practical constraints on the waveforms, namely total transmit power, peak-to-average-power ratio (PAR), constant modulus, and discrete phase alphabet. A Coordinate Descent (CD) based approach, called UNIQUE, is proposed in which at every single variable update of the algorithm we obtain the solution of the uni-variable optimization problems. The novelty of the paper comes from deriving a flexible waveform design problem applicable for the emerging 4D imaging MIMO radars with application to automotive radar systems. The simultaneous optimization leads to a trade-off between the two ISLRs and the simulation results illustrate significantly improved trade-off offered by the proposed methodologies.
A feedback model of the edge tone, using the adjoint Orr–Sommerfeld equation

Abstract The description of the feedback mechanism is one of the crucial points in the understanding of self-sustained flow oscillations, such as the edge tone or the cavity tone. In this paper a new model for the edge tone, using linear adjoint modes is proposed for low speeds, when acoustic effects are negligible. The two crucial points of the model are (i) a new relationship between the jet oscillation and the generated vortex at the edge tip and (ii) a new model for the effect of the generated vortex on the oscillation. The frequency corresponding to the optimum open-loop gain of the feedback mechanism was compared with experimental data and good agreement was found.
Unsupervised Pretraining for Object Detection by Patch Reidentification

Unsupervised representation learning achieves promising performances in pre-training representations for object detectors. However, previous approaches are mainly designed for image-level classiﬁcation, leading to suboptimal detection performance. To bridge the performance gap, this work proposes a simple yet effective representation learning method for object detection, named patch re-identiﬁcation (Re-ID), which can be treated as a contrastive pretext task to learn location-discriminative representation unsu-pervisedly, possessing appealing advantages compared to its counterparts. Firstly , unlike fully-supervised person Re-ID that matches a human identity in different camera views, patch Re-ID treats an important patch as a pseudo identity and contrastively learns its correspondence in two different image views, where the pseudo identity has different translations and transformations, enabling to learn discriminative features for object detection. Secondly , patch Re-ID is performed in D eeply U nsupervised manner to learn multi-level representations, appealing to object detection. Thirdly , extensive experiments show that our method sig-niﬁcantly outperforms its counterparts on COCO in all settings, such as different training iterations and data percentages. For example, Mask R-CNN initialized with our representation surpasses MoCo v2 and even its fully-supervised counterparts in all setups of training iterations ( e.g . 2.1 and 1.1 mAP improvement compared to MoCo v2 in 12k and 90k iterations respectively). Code will be released at https://github.com/dingjiansw101/DUPR .
Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

We present deep (265 ks) Chandra X-ray observations of PSO J352.4034−15.3373, a quasar at z = 5.831 that, with a radio-to-optical flux ratio of R > 1000, is one of the radio-loudest quasars in the early universe and is the only quasar with observed extended radio jets of kiloparsec scale at z ≳ 6. Modeling the X-ray spectrum of the quasar with a power law, we find a best fit of Γ=1.99−0.28+0.29 , leading to an X-ray luminosity of L2–10=1.26−0.33+0.45×1045ergs−1 and an X-ray to UV brightness ratio of α OX = −1.45 ± −0.11. We identify a diffuse structure 50 kpc (∼8″) to the NW of the quasar along the jet axis that corresponds to a 3σ enhancement in the angular density of emission and can be ruled out as a background fluctuation with a probability of P = 0.9985. While with few detected photons the spectral fit of the structure is uncertain, we find that it has a luminosity of L 2–10 ∼ 1044 erg s−1. These observations therefore potentially represent the most distant quasar jet yet seen in X-rays. We find no evidence for excess X-ray emission where the previously reported radio jets are seen (which have an overall linear extent of 0.″28), and a bright X-ray point source located along the jet axis to the SE is revealed by optical and NIR imaging to not be associated with the quasar.
Fragmentation in the massive G31.41+0.31 protocluster

Context. ALMA observations at 1.4 mm and ~0. ′′2 (~750 au) angular resolution of the Main core in the high-mass star-forming region G31.41+0.31 have revealed a puzzling scenario. On the one hand, the continuum emission looks very homogeneous and the core appears to undergo solid-body rotation, suggesting a monolithic core stabilized by the magnetic field; on the other hand, rotation and infall speed up toward the core center, where two massive embedded free-free continuum sources have been detected, pointing to an unstable core having undergone fragmentation. Aims. To establish whether the Main core is indeed monolithic or if its homogeneous appearance is due to a combination of large dust opacity and low angular resolution, we carried out millimeter observations at higher angular resolution and different wavelengths. Methods. We carried out ALMA observations at 1.4 mm and 3.5 mm that achieved angular resolutions of ~0. ′′1 (~375 au) and ~0. ′′075 (~280 au), respectively. VLA observations at 7 mm and 1.3 cm at even higher angular resolution, ~0. ′′05 (~190 au) and ~0. ′′07 (~260 au), respectively, were also carried out to better study the nature of the free-free continuum sources detected in the core. Results. The millimeter continuum emission of the Main core has been clearly resolved into at least four sources, A, B, C, and D, within 1″, indicating that the core is not monolithic. The deconvolved radii of the dust emission of the sources, estimated at 3.5 mm, are ~400–500 au; their masses range from ~15 to ~26 M⊙; and their number densities are several 109 cm−3. Sources A and B, located closer to the center of the core and separated by ~750 au, are clearly associated with two free-free continuum sources, likely thermal radio jets, and are brightest in the core. The spectral energy distribution of these two sources and their masses and sizes are similar and suggest a common origin. Source C has not been detected at centimeter wavelengths, while source D has been clearly detected at 1.3 cm. Source D is likely the driving source of an E–W SiO outflow previously detected in the region, which suggests that the free-free emission might be coming from a radio jet. Conclusions. The observations have confirmed that the Main core in G31 is collapsing, that it has undergone fragmentation, and that its homogeneous appearance previously observed at short wavelengths is a consequence of both high dust opacity and insufficient angular resolution. The low level of fragmentation together with the fact that the core is moderately magnetically supercritical, suggests that G31 could have undergone a phase of magnetically regulated evolution characterized by a reduced fragmentation efficiency, eventually leading to the formation of a small number of relatively massive dense cores.
Pufferfish: Communication-efficient Models At No Extra Cost

To mitigate communication overheads in distributed model training, several studies propose the use of compressed stochastic gradients, usually achieved by sparsification or quantization. Such techniques achieve high compression ratios, but in many cases incur either significant computational overheads or some accuracy loss. In this work, we present Pufferfish, a communication and computation efficient distributed training framework that incorporates the gradient compression into the model training process via training low-rank, pre-factorized deep networks. Pufferfish not only reduces communication, but also completely bypasses any computation overheads related to compression, and achieves the same accuracy as state-of-the-art, off-the-shelf deep models. Pufferfish can be directly integrated into current deep learning frameworks with minimum implementation modification. Our extensive experiments over real distributed setups, across a variety of large-scale machine learning tasks, indicate that Pufferfish achieves up to 1.64x end-to-end speedup over the latest distributed training API in PyTorch without accuracy loss. Compared to the Lottery Ticket Hypothesis models, Pufferfish leads to equally accurate, small-parameter models while avoiding the burden of"winning the lottery". Pufferfish also leads to more accurate and smaller models than SOTA structured model pruning methods.
A nonorthogonal tight-binding model for hydrocarbon molecules and nanostructures

In spirit of extended-Hückel approximations, we have developed a nonorthogonal tight-binding total energy model for hydrocarbons with only a few adjustable parameters. Our model reproduces the geometry structures, binding energies, on-site charge transfer and vibrational frequencies of a variety of hydrocarbon molecules reasonably well. Comparative calculations on carbon fullerenes and nanotubes using tight-binding model and density functional theory demonstrate the potential of applying this model to large scale simulations of carbon nanostructures.
Spezifische Mitose-Auslösung in normaler Rattenleber durch Serum von partiell hepatektomierten Ratten

Durch intraperitoneale Injektion von Serum partiell hepatektomierter Ratten in normale Ratten lassen sich regelmäßig Mitosen in der Leber normaler Ratten auslösen. Der mitoseauslösende Faktor ist nicht dialysabel und wirkt nicht mitose-auslösend auf das Parotis-Gewebe.
the release of InsulIn-lIke Growth f actor - I BY ovarIan Granulosa cells of PreGnant sows after lead and Mercur Y adMInIstratIon in Vitro

lead (Pb) and mercury (Hg) are reproductive and developmental toxicants even at very low doses. the general objective of this study was to examine the secretory activity of porcine ovarian granulosa cells of pregnant sows after the lead and mercury in vitro administration. ovarian granulosa cells were incubated with/without lead acetate, mercury chloride and follicle-stimulating hormone (FSH) for 18 hours. A maximal dose of Pb(CH 3 Coo) 2 . 3H 2 o/ HgCl 2 was 0.5 mg ml -1 ; group A - 0.25 mg.ml -1 , group B - 0.083 mg.ml -1 , group C - 0.063 mg.ml -1 , group D - 0.046 mg.ml -1 ; in case of FSH: group E - 1.0 ng.ml -1 , group G - 100 ng.ml -1 . Group F received FSH (1.0 ng.ml -1 ), lead acetate (0.083 mg.ml -1 ) and mercury chloride (0.083 mg.ml -1 ); group H received FSH (100 ng.ml -1 ), lead acetate (0.063 mg.ml -1 ) and mercury chloride (0.063 mg.ml -1 ). Concentrations of �GF–� were determined in 25–100 µL incubation medium by RIA. In our study a significant release of IGF-I by ovarian granulosa cells from pregnant sows was revealed after lead administration at doses of 0.5 mg.ml -1 and 0.25 mg.ml -1 . No significant changes at doses of 0.083 mg.ml -1 , 0.063 mg.ml -1 and 0.046 mg.ml -1 were demonstrated. �GF-� was stimulated by the Hg addition at dose of 0.083 mg.ml -1 . the con centrations 0.25 mg.ml -1 , 0.063 mg.ml -1 and 0.046 mg.ml -1 did not affect the release of
Hydrogen Production by Solar Thermochemical Water-Splitting/Methane-Reforming Process

Two different routes of solar thermochemical hydrogen production are reviewed. One is two-step water splitting cycle by using a metal-oxide redox pair. The first step is based on the thermal reduction of metal oxide, which is a highly endothermic process driven by concentrated solar thermal energy. The second step involves water decomposition with the thermally-reduced metal oxide. The first thermal reduction process requires very-high temperatures, which may be realized in sun-belt regions. Another hydrogen production route is solar reforming of natural gas (methane), which can convert methane to hydrogen via calorie-upgrading by using concentrated solar thermal energy. Solar reforming is currently the most advanced solar thermochemical process in sun belt. There is also possibility for the solar reforming to be applied for worldwide solar concentrating facilities where direct insolation is weaker than that in sun belt. Our experimental studies to improve the relevant catalytic technologies are shown and discussed.Copyright © 2003 by ASME
Theory of light absorption and non-radiative transitions in F-centres

A quantitative theory for the shapes of the absorption bands of F-centres is given on the basis of the Franck-Condon principle. Underlying the treatment are two simplifying assumptions: namely, (a) that the lattice can be approximately treated as a dielectric continuum; (b) that in obtaining the vibrational wave functions for the lattice, the effect of the F-centre can be considered as that of a static charge distribution. Under these assumptions, it is shown that the absorption constant as a function of frequency and temperature can be expressed in terms of the Bessel functions with imaginary arguments. The theoretical curves for the absorption constant compare very favourably with the experimental curves for all temperatures. Also considered in the paper are the probabilities of non-radiative transitions, which are important in connexion with the photo-conductivity observed following light absorption by F-centres. The treatment given differs from the qualitative considerations hitherto in one important aspect, namely, the strength of the coupling between the electron and the lattice is taken into account. The adiabatic wave functions for the F-centre electron required for the discussion are obtained by perturbation methods. The probability for an excited F-centre to return to its ground state by non-radiative transitions is shown to be negligible; similar transitions to the conduction band are, however, important if the excited state is separated from the conduction band by not much more than 0·1 eV. The temperature dependence of such transitions is complicated, but, for a wide range of temperatures, resembles e-w/kT. Tentative estimates show that the result is Consistent with the observed steep drop of the photo-conductive current with temperature.