Miracle-dz/UniFAR-FTUs huggingface dataset:
A transition mechanism for the spontaneous axisymmetric intensification of tropical cyclones

AbstractA mechanism for the transition of tropical cyclones (TCs) to the spontaneous rapid intensification (RI) phase is proposed based on numerical results of a three-dimensional full-physics model. The intensification phase of the simulated TC is divided into three subphases according to the rate of intensification: 1) a slowly intensifying phase, 2) an RI phase, and 3) an adjustment phase toward the quasi-steady state. The evolution of a TC vortex is diagnosed by the energy budget analysis and the degree of axisymmetric structure of the TC vortex, and the simulated TC is determined to be axisymmetrized 12 h before the onset of RI. It is found that equivalent potential temperature θe in the lowest layer suddenly increases inside the radius of maximum azimuthally averaged horizontal wind rma after the TC becomes nearly axisymmetric. Forward trajectory analyses revealed that the enhanced convective instability in the TC core region where the eyewall subsequently forms results from the increased inertial s.
Totally non-congruence Veech groups

Veech groups are discrete subgroups of SL(2, R) which play an important role in the theory of translation surfaces. For a special class of translation surfaces called origamis or square-tiled surfaces their Veech groups are subgroups of finite index of SL(2, Z). We show that each stratum of the space of translation surfaces contains infinitely many origamis whose Veech group is a totally non congruence group, i.e. it surjects to SL(2, Z/nZ) for any n.
Deformations of pairs of rational curves and quintic threefolds

This is one of a series of papers ([2], [3], [4]) that study the pairs of curves and hypersurfaces under the same motif: a fundamental property on the first order deformations of the pairs (Lemma 1.4, (1) below) has an effect on the normal bundle of the rational curves on the hypersurfaces. Each paper solves an independent problem with the same condition (Lemma 1.4), which addresses only one aspect of the normal bundles. In this paper, we let $X_0$ be a generic quintic threefolds in projective space $\mathbf P^4$ over complex numbers, and $C_0$ an immersed rational curve on $X_0$. We prove $$H^1(N_{c_0/X_0})=0,$$ where $c_0: \mathbf P^1\to X_0$ is the immersion of $\mathbf P^1$.
Ramosin: The First Antibacterial Peptide Identified on Bolitoglossa ramosi Colombian Salamander

The discovery and improvements of antimicrobial peptides (AMPs) have become an alternative to conventional antibiotics. They are usually small and heat-stable peptides, exhibiting inhibitory activity against Gram-negative and Gram-positive bacteria. In this way, studies on broad-spectrum AMPs found in amphibians with the remarkable capability to regenerate a wide array of tissues are of particular interest in the search for new strategies to treat multidrug-resistant bacterial strains. In this work, the use of bioinformatic approaches such as sequence alignment with Fasta36 and prediction of antimicrobial activity allowed the identification of the Ramosin peptide from the de novo assembled transcriptome of the plethodontid salamander Bolitoglossa ramosi obtained from post-amputation of the upper limb tissue, heart, and intestine samples. BLAST analysis revealed that the Ramosin peptide sequence is unique in Bolitoglossa ramosi. The peptide was chemically synthesized, and physicochemical properties were characterized. Furthermore, the in vitro antimicrobial activity against relevant Gram-positive and Gram-negative human pathogenic bacteria was demonstrated. Finally, no effect against eukaryotic cells or human red blood cells was evidenced. This is the first antibacterial peptide identified from a Colombian endemic salamander with interesting antimicrobial properties and no hemolytic activity.
The LMMP for log canonical 3-folds in char $p$

We prove that one can run the log minimal model program for log canonical $3$-fold pairs in characteristic $p>5$. In particular we prove the Cone Theorem, Contraction Theorem, the existence of flips and the existence of log minimal models for pairs with log divisor numerically equivalent to an effective divisor. These follow from our main results, which are that certain log minimal models are good.
Bounding the covolume of lattices in products

We study lattices in a product $G=G_{1}\times \cdots \times G_{n}$ of non-discrete, compactly generated, totally disconnected locally compact (tdlc) groups. We assume that each factor is quasi just-non-compact, meaning that $G_{i}$ is non-compact and every closed normal subgroup of $G_{i}$ is discrete or cocompact (e.g. $G_{i}$ is topologically simple). We show that the set of discrete subgroups of $G$ containing a fixed cocompact lattice $\unicode[STIX]{x1D6E4}$ with dense projections is finite. The same result holds if $\unicode[STIX]{x1D6E4}$ is non-uniform, provided $G$ has Kazhdan’s property (T). We show that for any compact subset $K\subset G$ , the collection of discrete subgroups $\unicode[STIX]{x1D6E4}\leqslant G$ with $G=\unicode[STIX]{x1D6E4}K$ and dense projections is uniformly discrete and hence of covolume bounded away from $0$ . When the ambient group $G$ is compactly presented, we show in addition that the collection of those lattices falls into finitely many $\operatorname{Aut}(G)$ -orbits. As an application, we establish finiteness results for discrete groups acting on products of locally finite graphs with semiprimitive local action on each factor. We also present several intermediate results of independent interest. Notably it is shown that if a non-discrete, compactly generated quasi just-non-compact tdlc group $G$ is a Chabauty limit of discrete subgroups, then some compact open subgroup of $G$ is an infinitely generated pro- $p$ group for some prime $p$ . It is also shown that in any Kazhdan group with discrete amenable radical, the lattices form an open subset of the Chabauty space of closed subgroups.
Weak integral conditions for BMO

We study the question of how much one can weaken the defining condition of BMO. Specifically, we show that if $Q$ is a cube in $\mathbb{R}^n$ and $h:[0,\infty)\to[0,\infty)$ is such that $h(t)\underset{t\to\infty}{\longrightarrow}\infty,$ then $$ \sup_{J \text{subcube} Q} \frac1{|J|}\int_J h(|\varphi-\frac1{|J|} \int_J\varphi |)<\infty \Longrightarrow \varphi\in BMO(Q). $$ Under some additional assumptions on $h$ we obtain estimates on $\|\varphi\|_{BMO}$ in terms of the supremum above. We also show that even though the condition $h(t)\underset{t\to\infty}{\longrightarrow}\infty$ is not necessary for this implication to hold, it becomes necessary if one considers the dyadic BMO.
Entropy of embedded surfaces in quasi-fuchsian manifolds

We compare critical exponent for quasi-Fuchsian groups acting on the hyperbolic 3-space, $\mathbb{H}^3$, and on invariant disks embedded in $\mathbb{H}^3$. We give a rigidity theorem for all embedded surfaces when the action is Fuchsian and a rigidity theorem for negatively curved surfaces when the action is quasi-Fuchsian.
The Neupert Effect in Active Stellar Coronae: Chromospheric Evaporation and Coronal Heating in the dMe Flare Star Binary UV Ceti

Evidence for coronal heating by chromospheric evaporation in flares of active dMe stars is presented through observations of the Neupert effect in high-frequency microwaves and soft X-rays. The Neupert effect, as originally found in solar flares, manifests itself in a close similarity between the soft X-ray light curve and the time integral of the simultaneous microwave light curve. It is interpreted as the signature of the accumulation of hot plasma due to heating by accelerated electrons in the chromosphere. We used the ROSAT and ASCA soft X-ray observatories and the Very Large Array (VLA) radio telescope (at 6 cm and 3.6 cm wavelengths) to monitor simultaneously the nearby dMe flare star binary Gliese 65 A+ B = UV Ceti during 9 hours on each of two consecutive days. We find several weakly polarized radio events that start contemporaneously (within a few minutes) with X-ray flares and then peak and decay as the X-ray flares develop gradually. A striking similarity to the temporal evolution of solar gradual events is found. We argue that the Neupert effect is best observed in relatively hard bands of the soft X-ray emission, but that its presence can be inferred from the much softer bands commonly used for stellar observations by use of the solar analogy. Together with spectral hardness observations of soft X-rays, the data suggest the operation of chromospheric evaporation on UV Cet. The observations thus indicate a causal relation between the nonthermal and thermal energies of the underlying electron populations. We find that stellar flares are, relative to solar flares, X-ray-weak. The ratio between the total energy radiated into the radio and the soft X-ray bands closely matches the corresponding ratio between the quiescent luminosities of active stars, perhaps implying similar mechanisms and similar efficiencies for the quiescent emission and for larger, single flares. Estimating the total kinetic energy in the electrons from the radio flux, we find that only a part is observed in soft X-rays, a discrepancy well known from solar flares.
Jsj Decompositions of Groups

This is an account of the theory of JSJ decompositions of finitely generated groups, as developed in the last twenty years or so. We give a simple general definition of JSJ decompositions (or rather of their Bass-Serre trees), as maximal universally elliptic trees. In general, there is no preferred JSJ decomposition, and the right object to consider is the whole set of JSJ decompositions, which forms a contractible space: the JSJ deformation space. We prove that JSJ decompositions exist for any finitely presented group $G$, without any assumption on edge groups. When edge groups are slender, we describe flexible vertices of JSJ decompositions as quadratically hanging extensions of 2-orbifold groups. Similar results hold in the presence of acylindricity, in particular for splittings of torsion-free CSA groups over abelian groups, and splittings of relatively hyperbolic groups over virtually cyclic or parabolic subgroups. Using trees of cylinders, we obtain canonical JSJ trees (which are invariant under automorphisms). We introduce the compatibility JSJ decomposition, replacing the property of being universally elliptic by the stronger property of being universally compatible. This yields a canonical compatibility JSJ tree, not just a deformation space. We show that it exists when $G$ is finitely presented. We give many examples, and we work throughout with relative decompositions (certain subgroups are required to be elliptic in all trees under consideration).
A2BCD: An Asynchronous Accelerated Block Coordinate Descent Algorithm With Optimal Complexity

In this paper, we propose the Asynchronous Accelerated Nonuniform Randomized Block Coordinate Descent algorithm (A2BCD), the first asynchronous Nesterov-accelerated algorithm that achieves optimal complexity. This parallel algorithm solves the unconstrained convex minimization problem, using p computing nodes which compute updates to shared solution vectors, in an asynchronous fashion with no central coordination. Nodes in asynchronous algorithms do not wait for updates from other nodes before starting a new iteration, but simply compute updates using the most recent solution information available. This allows them to complete iterations much faster than traditional ones, especially at scale, by eliminating the costly synchronization penalty of traditional algorithms. We first prove that A2BCD converges linearly to a solution with a fast accelerated rate that matches the recently proposed NU_ACDM, so long as the maximum delay is not too large. Somewhat surprisingly, A2BCD pays no complexity penalty for using outdated information. We then prove lower complexity bounds for randomized coordinate descent methods, which show that A2BCD (and hence NU_ACDM) has optimal complexity to within a constant factor. We confirm with numerical experiments that A2BCD outperforms NU_ACDM, which is the current fastest coordinate descent algorithm, even at small scale. We also derive and analyze a second-order ordinary differential equation, which is the continuous-time limit of our algorithm, and prove it converges linearly to a solution with a similar accelerated rate.
Wedge locality and asymptotic commutativity

In this paper, we study twist deformed quantum field theories obtained by combining the Wightman axiomatic approach with the idea of spacetime noncommutativity. We prove that the deformed fields with deformation parameters of opposite sign satisfy the condition of mutual asymptotic commutativity, which was used earlier in nonlocal quantum field theory as a substitute for relative locality. We also present an improved proof of the wedge localization property discovered for the deformed fields by Grosse and Lechner, and we show that the deformation leaves the asymptotic behavior of the vacuum expectation values in spacelike directions substantially unchanged.
Higher-order moments of velocity fluctuations in the wake of a short stack

The effect of jet velocity relative to the crossflow velocity on the higher-order moments of velocity fluctuations characteristics in the wake of stack is reported in this study. The cross-flow Reynolds number was ReD = 2.3×104 and the jet-to-cross-flow velocity ratio was varied from R = 0 to 3. The stack was partially immersed in a flat-plate turbulent boundary layer, with a boundary layer thickness-to-stack-height ratio of δ/H = 0.5 at the location of the stack. The skewness factor, flatness factor and triple correlations are found to be influenced by the flow regime. The deviation of skewness and flatness factors from the Gaussian fluctuation values of zero and 3 are more pronounced outside the wake centre region due to the presence of the separated shear layers and vortex structures. The high values of the skewness and flatness factors for all values of velocity ratio within the vicinity of the stack free end are related to the tip vortex structures near the stack free end which decrease in strength as the value of R increases. In addition, the separated shear layers from both sides of the stack contribute to the high values observed away from the wake centreline.
Crossover phenomena in the critical behavior for long-range models with power-law couplings

This is a short review of the two papers on the $x$-space asymptotics of the critical two-point function $G_{p_c}(x)$ for the long-range models of self-avoiding walk, percolation and the Ising model on $\mathbb{Z}^d$, defined by the translation-invariant power-law step-distribution/coupling $D(x)\propto|x|^{-d-\alpha}$ for some $\alpha>0$. Let $S_1(x)$ be the random-walk Green function generated by $D$. We have shown that $\bullet~~S_1(x)$ changes its asymptotic behavior from Newton ($\alpha>2$) to Riesz ($\alpha<2$), with log correction at $\alpha=2$; $\bullet~~G_{p_c}(x)\sim\frac{A}{p_c}S_1(x)$ as $|x|\to\infty$ in dimensions higher than (or equal to, if $\alpha=2$) the upper critical dimension $d_c$ (with sufficiently large spread-out parameter $L$). The model-dependent $A$ and $d_c$ exhibit crossover at $\alpha=2$. The keys to the proof are (i) detailed analysis on the underlying random walk to derive sharp asymptotics of $S_1$, (ii) bounds on convolutions of power functions (with log corrections, if $\alpha=2$) to optimally control the lace-expansion coefficients $\pi_p^{(n)}$, and (iii) probabilistic interpretation (valid only when $\alpha\le2$) of the convolution of $D$ and a function $\varPi_p$ of the alternating series $\sum_{n=0}^\infty(-1)^n\pi_p^{(n)}$. We outline the proof, emphasizing the above key elements for percolation in particular.
GNSS Ocean Bistatic Statistical Scattering in the Time-Varying Regime: Simulation and Model Validation

This work develops around the problem of modeling statistics and correlation properties of the Global Navigation Satellite System (GNSS) L-band signal scattered by the moving ocean surface, presented in the companion article by Principe et al. (2021). The modeling work is here completed by deriving an effective method for simulation of the received signal as well as by making a validation study based on simulated and real data. The simulation of the stochastic process embedding the design statistical properties, the temporal correlation model and the system and surface parameters is intricate, in general, and provides a useful tool for researchers interested in modeling and simulation of GNSS reflected signals from a time-evolving sea surface. The GNSS received waveforms after 1 ms coherent integration are simulated and the correlation properties of the specular and near-specular points are compared to the theoretical model and to results from real data. Real raw data were collected during an aircraft mission in the Gulf of Finland and in a spaceborne scenario with Cyclone Global Navigation Satellite System (CYGNSS) satellites. Comparisons show good agreement among simulations, model, and real data, and demonstrate that the estimated correlation time of the GNSS-R signal fits real data with higher accuracy with respect to the case in which sea correlation is not accounted, especially when the receiving platform velocity is moderate.
Political ethnography and Russian studies in a time of conflict

ABSTRACT As reliable and unfiltered access to Russia and Russians becomes a fraught issue for social scientists who wish to conduct surveys, focus groups, do ethnographies, or interview elite actors, the war presents scholars with an opportunity to reflect on questions of what data collection means, and on better communication between quantitative and qualitative scholars. Similarly, it forces us confront the extractive and colonial nature of knowledge production; the war reveals how social science has always relied on, but not really acknowledged, the labor of native scholars, but can no longer ignore indigenously produced work, particularly qualitative research. In this review piece, the author highlights both blind spots in the potential communication between political scientists and other social scientists, and already-existing points of connection that can be further expanded, precisely because of, not despite the war.
Variational multiscale proper orthogonal decomposition: Navier‐stokes equations

We develop a variational multiscale proper orthogonal decomposition (POD) reduced‐order model (ROM) for turbulent incompressible Navier‐Stokes equations. Under two assumptions on the underlying finite element approximation and the generation of the POD basis, the error analysis of the full discretization of the ROM is presented. All error contributions are considered: the spatial discretization error (due to the finite element discretization), the temporal discretization error (due to the backward Euler method), and the POD truncation error. Numerical tests for a three‐dimensional turbulent flow past a cylinder at Reynolds number Re = 1000 show the improved physical accuracy of the new model over the standard Galerkin and mixing‐length POD ROMs. The high computational efficiency of the new model is also showcased. Finally, the theoretical error estimates are confirmed by numerical simulations of a two‐dimensional Navier‐Stokes problem. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 641–663, 2014
Related Reflections to the Axioms of Separation in Semigroups with Topologies and Some Applications

In this paper we study the reflections of the category of topological and semitopological semigroups on the category of the class of topological spaces satisfying separation axioms $T_{0}$, $T_{1}$, $T_{2}$, $T_{3}$ and regular and we apply its properties for to find conditions under which a topological semigroup has the Souslin property.
Adjoint functor theorems for ∞ ‐categories

Adjoint functor theorems give necessary and sufficient conditions for a functor to admit an adjoint. In this paper, we prove general adjoint functor theorems for functors between ∞ ‐categories. One of our main results is an ∞ ‐categorical generalization of Freyd's classical General Adjoint Functor Theorem. As an application of this result, we recover Lurie's adjoint functor theorems for presentable ∞ ‐categories. We also discuss the comparison between adjunctions of ∞ ‐categories and homotopy adjunctions, and give a treatment of Brown representability for ∞ ‐categories based on Heller's purely categorical formulation of the classical Brown representability theorem.
Path-by-path uniqueness of infinite-dimensional stochastic differential equations

Consider the stochastic differential equation $\mathrm dX_t = -A X_t \,\mathrm dt + f(t, X_t) \,\mathrm dt + \mathrm dB_t$ in a (possibly infinite-dimensional) separable Hilbert space, where $B$ is a cylindrical Brownian motion and $f$ is a just measurable, bounded function. If the components of $f$ decay to 0 in a faster than exponential way we establish path-by-path uniqueness for mild solutions of this stochastic differential equation. This extends A. M. Davie's result from $\mathbb R^d$ to Hilbert space-valued stochastic differential equations.
Hasse–Schmidt derivations versus classical
 derivations

In this paper we survey the notion and basic results on multivariate Hasse--Schmidt derivations over arbitrary commutative algebras and we associate to such an object a family of classical derivations. We study the behavior of these derivations under the action of substitution maps and we prove that, in characteristic $0$, the original multivariate Hasse--Schmidt derivation can be recovered from the associated family of classical derivations. Our constructions generalize a previous one by M. Mirzavaziri in the case of a base field of characteristic $0$.
Degenerations of Ruijsenaars-van Diejen operator and q-Painleve equations

It is known that the Painleve VI is obtained by connection preserving deformation of some linear differential equations, and the Heun equation is obtained by a specialization of the linear differential equations. We inverstigate degenerations of the Ruijsenaars-van Diejen difference opearators and show difference analogues of the Painleve-Heun correspondence.
The galaxy two-point correlation function down to V = 26 magnitudes on 0°.5 scales

We extend the measurement of the galaxy angular two-point correlation function ω(θ) down to V∼26 mag on scales θ≤0°. 45. For this, we used the Palomar 200 inch (5.08 m) Four-Shooter CCD-array to image two deep radio-optical survey regions (0.2 deg 2 ) with contiguous mosaics in Gunn gri, yielding in total ∼60,000 faint galaxies down to V∼26 mag. Here, we present the first results for one mosaic in Gunn g.
Large Deviation Multifractal Analysis of a Process Modeling TCP CUBIC

Multifractal characteristics of the Internet traffic have been discovered and discussed in several research papers so far. However, the origin of this phenomenon is still not fully understood. It has been proven that the congestion control mechanism of the Internet transport protocol, i.e., the mechanism of TCP Reno can generate multifractal traffic properties. Nonetheless, TCP Reno does not exist in today's network any longer, surprisingly traffic multifractality has still been observed. In this paper we give the theoretical proof that TCP CUBIC, which is the default TCP version in the Linux world, can generate multifractal traffic. We give the multifractal spectrum of TCP CUBIC traffic and compare it with the multifractal spectrum of TCP Reno traffic. Moreover, we present the multifractal spectrum for a more general model, where TCP CUBIC and TCP Reno are special cases. Our results also show that TCP CUBIC produces less bursty traffic than TCP Reno.