cssi/SciSciGPT-SciSciNet huggingface dataset:
18F-labeled biomolecules for PET studies in the neurosciences

Abstract 18F, a positron emitting isotope of fluorine, has a half-life of 110 min and a positron energy of 0.635 MeV. Positron emission tomography (PET), in conjunction with appropriate radiotracers labeled with 18F, has been used to assess functional activity, biochemical transformations and drug pharmacokinetics and pharmacodynamics in the human and animal body. The PET method, 18F-labeling of organic molecules, and some of the applications of 18F-labeled compounds in the neurosciences (brain and heart) are described.
Medical Subject Heading (MeSH) annotations illuminate maize genetics and evolution

High-density marker panels and/or whole-genome sequencing, coupled with advanced phenotyping pipelines and sophisticated statistical methods, have dramatically increased our ability to generate lists of candidate genes or regions that are putatively associated with phenotypes or processes of interest. However, the speed with which we can validate genes, or even make reasonable biological interpretations about the principles underlying them, has not kept pace. A promising approach that runs parallel to explicitly validating individual genes is analyzing a set of genes together and assessing the biological similarities among them. This is often achieved via gene ontology analysis, a powerful tool that involves evaluating publicly available gene annotations. However, additional resources such as Medical Subject Headings (MeSH) can also be used to evaluate sets of genes to make biological interpretations. In this manuscript, we describe utilizing MeSH terms to make biological interpretations in maize. MeSH terms are assigned to PubMed-indexed manuscripts by the National Library of Medicine, and can be directly mapped to genes to develop gene annotations. Once mapped, these terms can be evaluated for enrichment in sets of genes or similarity between gene sets to provide biological insights. Here, we implement MeSH analyses in five maize datasets to demonstrate how MeSH can be leveraged by the maize and broader crop-genomics community. We demonstrate that MeSH terms can be effectively leveraged to generate hypotheses and make biological interpretations in maize, and we provide a pipeline that enables the use of MeSH terms in other plant species.
Long-range magnetic ordering in iron jarosites prepared by redox-based hydrothermal methods.

The iron jarosites, plumbojarosite, Pb0.5Fe3(OH)6(SO4)2, argentojarosite, AgFe3(OH)6(SO4)2, and thallium jarosite, TlFe3(OH)6(SO4)2, along with the selenate-capped jarosite analogues of potassium, KFe3(OH)6(SeO4)2, and rubidium, RbFe3(OH)6(SeO4)2, have been prepared in their analytically pure forms by employing redox-based hydrothermal methods. The crystal structures of these materials have been determined, and all are found to be essentially isostructrual including Pb0.5Fe3(OH)6(SO4)2, which is distinct from the structure reported for naturally mined samples. All iron jarosites show long-range order (LRO), signified by a sharp transition temperature, TN, which falls in the narrow temperature range of 61.4 ± 5 K. The mechanism responsible for this ordering has been established by examining magnetostructural correlations for the jarosites possessing various interlayer cation and capping groups. We show that all magnetic properties of jarosites, including LRO, find their origin in the basic magnetic unit, t...
Palladium-Catalyzed Reactions of N-Allylbenzotriazoles with Amines: Intramolecular Allylamination Routes to 2-Vinylpyrrolidines and 2-Vinylpiperidines

Reactions of allylbenzotriazole (4a−d) with 1-bromo-3-chloropropane, 1-bromo-2-methyl-3-chloropropane, epibromohydrin (8), and 1-bromo-4-chlorobutane afforded the corresponding α-substituted allylb...
One prophage WO gene rescues cytoplasmic incompatibility in Drosophila melanogaster.

Wolbachia are maternally inherited, intracellular bacteria at the forefront of vector control efforts to curb arbovirus transmission. In international field trials, the cytoplasmic incompatibility (CI) drive system of wMel Wolbachia is deployed to replace target vector populations, whereby a Wolbachia-induced modification of the sperm genome kills embryos. However, Wolbachia in the embryo rescue the sperm genome impairment, and therefore CI results in a strong fitness advantage for infected females that transmit the bacteria to offspring. The two genes responsible for the wMel-induced sperm modification of CI, cifA and cifB, were recently identified in the eukaryotic association module of prophage WO, but the genetic basis of rescue is unresolved. Here we use transgenic and cytological approaches to demonstrate that maternal cifA expression independently rescues CI and nullifies embryonic death caused by wMel Wolbachia in Drosophila melanogaster. Discovery of cifA as the rescue gene and previously one of two CI induction genes establishes a “Two-by-One” model that underpins the genetic basis of CI. Results highlight the central role of prophage WO in shaping Wolbachia phenotypes that are significant to arthropod evolution and vector control.
Phosphoric acid mediated tautomerism of imines: addition of a secondary enamine intermediate to aldehydes

Abstract A phosphoric acid derivative has been shown to promote the addition between an imine and several aldehyde substrates through an enamine intermediate to give cross-aldol condensation products. The reaction scope and preliminary mechanistic investigations will be presented.
Chemistry of Gold in Molten Alkali Metal Polychalcophosphate Fluxes. Synthesis and Characterization of the Low-Dimensional Compounds A3AuP2Se8 (A = K, Rb, Cs), A2Au2P2Se6 (A = K, Rb), A2AuPS4 (A = K, Rb, Cs), and AAuP2S7 (A = K, Rb)

The reaction of Au with a molten mixture of A2Q/P2Q5/Q (Q = S, Se) produced the quaternary compounds A3AuP2Se8 (A = K, Rb, Cs) (I−III), A2Au2P2Se6 (A = K, Rb) (IV, V), A2AuPS4 (A = K, Rb, Cs) (VI−V...
G Protein–Coupled Estrogen Receptor Is Not Required for Sex Determination or Ovary Function in Zebrafish

Estrogens regulate vertebrate development and function through binding to nuclear estrogen receptors α and β (ERα and ERβ) and the G protein-coupled estrogen receptor (GPER). Studies in mutant animal models demonstrated that ERα and ERβ are required for normal ovary development and function. However, the degree to which GPER signaling contributes to ovary development and function is less well understood. Previous studies using cultured fish oocytes found that estradiol inhibits oocyte maturation in a GPER-dependent manner, but whether GPER regulates oocyte maturation in vivo is not known. To test the hypothesis that GPER regulates oocyte maturation in vivo, we assayed ovary development and function in gper mutant zebrafish. We found that homozygous mutant gper embryos developed into male and female adults with normal sex ratios. Adult mutant fish exhibited normal secondary sex characteristics and fertility. Additionally, mutant ovaries were histologically normal. We observed no differences in the number of immature versus mature oocytes in mutant versus wild-type ovaries from both young and aged adults. Furthermore, expression of genes associated with sex determination and ovary function was normal in gper mutant ovaries compared with wild type. Our findings suggest that GPER is not required for sex determination, ovary development, or fertility in zebrafish.
Asymmetric Hydrogenation of o-Alkoxy-Substituted Arylenamides

A series of (2-alkoxyaryl)glycinols have been prepared in up to 97.8% ee by asymmetric hydrogenation with cationic rhodium Me-BPE or Me-DuPhos complexes. Others have shown that the presence of ortho substituents on related α-arylenamides causes a decrease in enantioselectivity. However, in this study it was found that o-alkoxy α-arylenamides were reduced with high enantioselectivity irrespective of substituent size.
A Simple and Efficient l-Prolinamide-Catalyzed α-Selenenylation Reaction of Aldehydes

An efficient and simple l-prolinamide-catalyzed α-selenenylation reaction of aldehydes with N-(phenylseleno)phthalimide has been developed for the efficient preparation of α-phenylselenoaldehydes. ...
Endogenous protection from ischemic brain injury by preconditioned monocytes

Exposure to low-dose lipopolysaccharide (LPS) before cerebral ischemia is neuroprotective in stroke models, a phenomenon termed preconditioning (PC). Although it is well established that LPS-PC induces central and peripheral immune responses, the cellular mechanisms modulating ischemic injury remain unclear. Here, we investigated the role of immune cells in the brain protection afforded by PC and tested whether monocytes may be reprogrammed by ex vivo LPS exposure, thus modulating inflammatory injury after cerebral ischemia in male mice. We found that systemic injection of low-dose LPS induces a Ly6Chi monocyte response that protects the brain after transient middle cerebral artery occlusion (MCAO) in mice. Remarkably, adoptive transfer of monocytes isolated from preconditioned mice into naive mice 7 h after transient MCAO reduced brain injury. Gene expression and functional studies showed that IL-10, inducible nitric oxide synthase, and CCR2 in monocytes are essential for neuroprotection. This protective activity was elicited even if mouse or human monocytes were exposed ex vivo to LPS and then injected into male mice after stroke. Cell-tracking studies showed that protective monocytes are mobilized from the spleen and reach the brain and meninges, where they suppress postischemic inflammation and neutrophil influx into the brain parenchyma. Our findings unveil a previously unrecognized subpopulation of splenic monocytes capable of protecting the brain with an extended therapeutic window and provide the rationale for cell therapies based on the delivery of autologous or allogeneic protective monocytes in patients after ischemic stroke.SIGNIFICANCE STATEMENT Inflammation is a key component of the pathophysiology of the brain in stroke, a leading cause of death and disability with limited therapeutic options. Here, we investigate endogenous mechanisms of protection against cerebral ischemia. Using lipopolysaccharide (LPS) preconditioning (PC) as an approach to induce ischemic tolerance in mice, we found generation of neuroprotective monocytes within the spleen, from which they traffic to the brain and meninges, suppressing postischemic inflammation. Importantly, systemic LPS-PC can be mimicked by adoptive transfer of in vitro-preconditioned mouse or human monocytes at translational relevant time points after stroke. This model of neuroprotection may facilitate clinical efforts to increase the efficacy of BM mononuclear cell treatments in acute neurological diseases such as cerebral ischemia.
Facile acidic hydrolysis and displacement reactions of 2‐chloro‐and 2,9‐dichloro‐1,10‐phenanthroline

Treatment of 2-chloro- or 2,9-dichloro-1,10-phenanthroline with aqueous HBr or aqueous H2SO4 at 120°C yielded 1,10-phenanthroline-2(1H)-one or 1,10-dihydro-1,10-phenanthroline-2,9-dione, respectively. The hydrolysis of 2,9-dichloro-1,10-phenanthroline with 37% aqueous HC1 led to the half hydrolyzed amide and the bis-amide. Under comparable reactions conditions, using aqueous HBr, H2SO4 or HC1, 2-chloropyridine was found to be hydrolytically stable. On the other hand, 2-chloro- or 2,9-dichloro-1,10-phenanthroline on heating with 57% aqueous HI afforded the HI salts of 2-iodo- or 2,9-diiodo-1,10-phenanthroline, which could be isolated. These salts on treatment with aqueous ammonium hydroxide led to good yields of 2-iodo- and 2, 9-diiodo-1,10-phenanthroline, respectively. Treatment of 2-chloropyridine with 57% aqueous HI under similar reaction conditions led to 2-iodopyridine in a 10% conversion.
Replacement of the 1‘,4‘-Phenylene Region in 5,10-Dideaza-5,6,7,8-tetrahydrofolic Acid (DDATHF) by 4,5,6,7-Tetrahydrobenzo[c]thiophene and 4,5,6,7-Tetrahydroisobenzofuran Nuclei

Two new analogs of DDATHF, in which the 1‘,4‘-phenylene unit is replaced by 4,5,6,7-tetrahydrobenzo[c]thiophene and 4,5,6,7-tetrahydroisobenzofuran nuclei, have been prepared and evaluated for in v...
Condensed-phase products in heterogeneous reactions: N2O5, ClONO2, and HNO3 reacting on ice films at 185 K

Heterogeneous reactions are important in a wide variety of chemical processes. In many cases reactions on a surface will change both the physical and chemical characteristics of the surface, which in turn will change the surface reactivity toward further gas/surface collisions. As a case study of relevance to the atmosphere, we have investigated the reactions of the NOy species ClONO2, N2O5, and HNO3 on thin ice films representative of water-ice polar stratospheric clouds (type II PSCs). Although these species are known to produce HNO3 upon reacting with the ice surface, the phase, composition, and state of adsorption (physical versus chemical) of the surface reaction product are not known. These reactions were studied using a Knudsen cell reactor to probe heterogeneous reaction rates, mass spectrometry to identify gas-phase reactants and products, and FTIR reflection−absorption spectroscopy to probe the phase and composition of the condensed phase. Under ice frost point conditions at 185 K, each NOy spec...
Rapid, microwave-assisted synthesis of N1-substituted 3-amino-1,2,4-triazoles

Abstract A robust, regioselective synthesis of 3-amino-1,2,4-triazoles is described. This reaction employs a key intermediate 2, which is coupled to carboxylic acids in good yields to afford intermediates 3a–d. These entities, in turn, react with a variety of hydrazines or hydrazine hydrochlorides to provide proposed intermediates 4a–j, which under microwave conditions cyclize to the desired 3-amino-1,2,4-triazoles (compounds 5a–j). This approach permits the rapid synthesis of regioselective N1-substituted 3-amino-1,2,4-triazoles, and is shown to afford a variety of such compounds in 34–70% isolated yields.
Highly stereoselective synthesis of trans,trans-4-aryl-2,3-oxetanedimethanols: Preparation of oxetanocin a analogues

A short (5-step) synthesis of the oxetanocin A analogues 12a and 12b has been accomplished, with very good stereoselectivity in the key iodocyclization step.
Reductive aromatization of quinols: synthesis of the C-arylglycoside nucleus of the papulacandins and chaetiacandin.

Nucleophilic 1,2-addition of lithiated glycal 9b to functionalized quinone 7 provided, after reductive aromatization, C-arylglycoside 11b. Treatment with mCPBA afforded the tricyclic papulacandin framework. Alternatively, hydroboration gave the chaetiacandin nucleus.
Sharpless Asymmetric Dihydroxylation of 5-Aryl-2-vinylfurans: Application to the Synthesis of the Spiroketal Moiety of Papulacandin D

Using the Sharpless catalytic asymmetric dihydroxylation reaction on 5-aryl-2-vinylfurans, diols are produced in high enantioexcess. The resulting diols can be efficiently transformed into the spiroketal ring precursor of the antifungal compound papulacandin D. Stereoselective reduction of this precursor followed by a diastereoselective dihydroxylation completes the synthesis of a mannopyranoside isomer of a papulacandin derivative.
A New Series of Oxygen-Deficient Perovskites in the NaTixNb1-xO3-0.5x System: Synthesis, Crystal Chemistry, and Energetics

A series of perovskites with the compositions NaTixNb1-xO3-0.5x (0 ≤ x ≤ 0.2) has been synthesized for the first time using the sol−gel method. Combined Rietveld analysis of powder neutron and X-ra...
A route to artificial glycoconjugates and oligosaccharides via enzymatically resolved glycals: Dramatic effects of the handedness of the sugar domain upon the properties of an anthracycline drug

Racemic, fully synthetic glycals of considerable structural variety may be kinetically resolved via enzymatically mediated transesterification using Lipase PS-30 from Pseudamanas cepacia as catalyst and vinyl acetate as acyl donor. This methodology provides convenient access to a pool of optically enricfed D- and L-glycals. These glycals may be employed as building blocks, both as glycosyl donors and glycosyl acceptors, to generate artificial oligosaccharides
Modeling of solidification microstructure evolution in laser powder bed fusion fabricated 316L stainless steel using combined computational fluid dynamics and cellular automata

Abstract This work presents a novel modeling framework combining computational fluid dynamics (CFD) and cellular automata (CA), to predict the solidification microstructure evolution of laser powder bed fusion (PBF) fabricated 316 L stainless steel. A CA model is developed which is based on the modified decentered square method to improve computational efficiency. Using this framework, the fluid dynamics of the melt pool flow in the laser melting process is found to be mainly driven by the competing Marangoni force and the recoil pressure on the liquid metal surface. Evaporation occurs at the front end of the laser spot. The initial high temperature occurs in the center of the laser spot. However, due to Marangoni force, which drives high-temperature liquid flowing to low-temperature region, the highest temperature region shifts to the front side of the laser spot where evaporation occurs. Additionally, the recoil pressure pushes the liquid metal downward to form a depression zone. The simulated melt pool depths are compared well with the experimental data. Additionally, the simulated solidification microstructure using the CA model is in a good agreement with the experimental observation. The simulations show that higher scan speeds result in smaller melt pool depth, and lack-of-fusion pores can be formed. Higher laser scan speed also leads to finer grain size, larger laser-grain angle, and higher columnar grain contents, which are consistent with experimental observations. This model can be potentially used as a tool to optimize the metal powder bed fusion process, through generating desired microstructure and resultant material properties.
Curvature pinching estimate and singularities of the Ricci flow

In this paper, we first derive a pinching estimate on the traceless Ricci curvature in term of scalar curvature and Weyl tensor under the Ricci flow. Then we apply this estimate to study finite-time singularity behavior. We show that if the scalar curvature is uniformly bounded, then the Weyl tensor has to blow up, as a consequence, the corresponding singularity model must be Ricci flat with non-vanishing Weyl tensor.
Avoiding Fractional Powers over the Natural Numbers

We study the lexicographically least infinite $a/b$-power-free word on the alphabet of non-negative integers. Frequently this word is a fixed point of a uniform morphism, or closely related to one. For example, the lexicographically least $7/4$-power-free word is a fixed point of a $50847$-uniform morphism. We identify the structure of the lexicographically least $a/b$-power-free word for three infinite families of rationals $a/b$ as well many "sporadic" rationals that do not seem to belong to general families. To accomplish this, we develop an automated procedure for proving $a/b$-power-freeness for morphisms of a certain form, both for explicit and symbolic rational numbers $a/b$. Finally, we establish a connection to words on a finite alphabet. Namely, the lexicographically least $27/23$-power-free word is in fact a word on the finite alphabet $\{0, 1, 2\}$, and its sequence of letters is $353$-automatic.
Covariance models on the surface of a sphere: when does it matter?

There is a growing interest in developing covariance functions for processes on the surface of a sphere because of the wide availability of data on the globe. Utilizing the one-to-one mapping between the Euclidean distance and the great circle distance, isotropic and positive definite functions in a Euclidean space can be used as covariance functions on the surface of a sphere. This approach, however, may result in physically unrealistic distortion on the sphere especially for large distances. We consider several classes of parametric covariance functions on the surface of a sphere, defined with either the great circle distance or the Euclidean distance, and investigate their impact upon spatial prediction. We fit several isotropic covariance models to simulated data as well as real data from National Center for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis on the sphere. We demonstrate that covariance functions originally defined with the Euclidean distance may not be adequate for some global data. Copyright © 2015 John Wiley & Sons, Ltd.
Regular supercuspidal representations

We show that, in good residual characteristic, most supercuspidal representations of a tamely ramified reductive p-adic group G arise from pairs (S,\theta), where S is a tame elliptic maximal torus of G, and \theta is a character of S satisfying a simple root-theoretic property. We then give a new expression for the roots of unity that appear in the Adler-DeBacker-Spice character formula for these supercuspidal representations and use it to show that this formula bears a striking resemblance to the character formula for discrete series representations of real reductive groups. Led by this, we explicitly construct the local Langlands correspondence for these supercuspidal representations and prove stability and endoscopic transfer in the case of toral representations. In large residual characteristic this gives a construction of the local Langlands correspondence for almost all supercuspidal representations of reductive p-adic groups.
Schur dynamics of the Schur processes

Abstract We construct discrete time Markov chains that preserve the class of Schur processes on partitions and signatures. One application is a simple exact sampling algorithm for q volume -distributed skew plane partitions with an arbitrary back wall. Another application is a construction of Markov chains on infinite Gelfand–Tsetlin schemes that represent deterministic flows on the space of extreme characters of the infinite-dimensional unitary group.
Fast Local Voltage Control Under Limited Reactive Power: Optimality and Stability Analysis

High penetration of distributed energy resources presents several challenges and opportunities for voltage regulation in power distribution systems. A local reactive power (VAR) control framework will be developed that can fast respond to voltage mismatch and address the robustness issues of (de-)centralized approaches against communication delays and noises. Using local bus voltage measurements, the proposed gradient-projection based schemes explicitly account for the VAR limit of every bus, and are proven convergent to a surrogate centralized problem with proper parameter choices. This optimality result quantifies the capability of local VAR control without requiring any real-time communications. The proposed framework and analysis generalize earlier results on the droop VAR control design, which may suffer from under-utilization of VAR resources in order to ensure stability. Numerical tests have demonstrated the validity of our analytical results and the effectiveness of proposed approaches implemented on realistic three-phase systems.
Concise complexity analyses for trust region methods

Concise complexity analyses are presented for simple trust region algorithms for solving unconstrained optimization problems. In contrast to a traditional trust region algorithm, the algorithms considered in this paper require certain control over the choice of trust region radius after any successful iteration. The analyses highlight the essential algorithm components required to obtain certain complexity bounds. In addition, a new update strategy for the trust region radius is proposed that offers a second-order complexity bound.
Circle actions and scalar curvature

We construct metrics of positive scalar curvature on manifolds with circle actions. One of our main results is that there exist $S^1$-invariant metrics of positive scalar curvature on every $S^1$-manifold which has a fixed point component of codimension 2. As a consequence we can prove that there are non-invariant metrics of positive scalar curvature on many manifolds with circle actions. Results from equivariant bordism allow us to show that there is an invariant metric of positive scalar curvature on the connected sum of two copies of a simply connected semi-free $S^1$-manifold $M$ of dimension at least six provided that $M$ is not $\text{spin}$ or that $M$ is $\text{spin}$ and the $S^1$-action is of odd type. If $M$ is spin and the $S^1$-action of even type then there is a $k>0$ such that the equivariant connected sum of $2^k$ copies of $M$ admits an invariant metric of positive scalar curvature if and only if a generalized $\hat{A}$-genus of $M/S^1$ vanishes.
Climbing the Kaggle Leaderboard by Exploiting the Log-Loss Oracle

In the context of data-mining competitions (e.g., Kaggle, KDDCup, ILSVRC Challenge), we show how access to an oracle that reports a contestant's log-loss score on the test set can be exploited to deduce the ground-truth of some of the test examples. By applying this technique iteratively to batches of $m$ examples (for small $m$), all of the test labels can eventually be inferred. In this paper, (1) We demonstrate this attack on the first stage of a recent Kaggle competition (Intel & MobileODT Cancer Screening) and use it to achieve a log-loss of $0.00000$ (and thus attain a rank of #4 out of 848 contestants), without ever training a classifier to solve the actual task. (2) We prove an upper bound on the batch size $m$ as a function of the floating-point resolution of the probability estimates that the contestant submits for the labels. (3) We derive, and demonstrate in simulation, a more flexible attack that can be used even when the oracle reports the accuracy on an unknown (but fixed) subset of the test set's labels. These results underline the importance of evaluating contestants based only on test data that the oracle does not examine.
Exact results on O (alpha**2) single bremsstrahlung corrections to low angle Bhabha scattering at LEP / SLC energies

In this thesis exact results on O(alpha^2) single bremsstrahlung corrections to low angle Bhabha scattering at LEP/SLC energies are given. The calculation represents the last outstanding theoretical second order subleading electroweak contribution for that process, needed to determine the experimental luminosity at second generation LEP detectors below the 0.1% precision threshold. The exact, fully differential result is obtained by employing analytical as well as computer-algebraic methods and includes terms up to O(0.05%) relative to the Born cross section. The initial output of over 20,000 terms could be reduced to 90, only 18 of which are shown to be numerically relevant and for which a simple logarithmic ansatz is derived, that is in remarkable agreement with the complete answer. Strong consistency checks are performed, including Ward-Takahashi identities and tests on the right infrared limit according to the Yennie, Frautschi and Suura program. Monte Carlo results for the integrated cross section are compared with existing calculations in the leading logarithmic approximation for a chosen set of experimental cuts. The size of the missing subleading terms is found to be small but non negligible in the context of setting stringent limits on Standard Model predictions and thus its realm of validity.
Preperiodic portraits for unicritical polynomials over a rational function field

Let $K$ be an algebraically closed field of characteristic zero, and let $\mathcal{K} := K(t)$ be the rational function field over $K$. For each $d \ge 2$, we consider the unicritical polynomial $f_d(z) := z^d + t \in \mathcal{K}[z]$, and we ask the following question: If we fix $\alpha \in \mathcal{K}$ and integers $M \ge 0$, $N \ge 1$, and $d \ge 2$, does there exist a place $\mathfrak{p} \in \operatorname{Spec} K[t]$ such that, modulo $\mathfrak{p}$, the point $\alpha$ enters into an $N$-cycle after precisely $M$ steps under iteration by $f_d$? We answer this question completely, concluding that the answer is generally affirmative and explicitly giving all counterexamples. This extends previous work by the author in the case that $\alpha$ is a constant point.
Coarse differentiation and quantitative nonembeddability for Carnot groups

Abstract We give lower bound estimates for the macroscopic scale of coarse differentiability of Lipschitz maps from a Carnot group with the Carnot–Caratheodory metric ( G , d c c ) to a few different classes of metric spaces. Using this result, we derive lower bound estimates for quantitative nonembeddability of Lipschitz embeddings of G into a metric space ( X , d X ) if X is either an Alexandrov space with nonpositive or nonnegative curvature, a superreflexive Banach space, or another Carnot group that does not admit a biLipschitz homomorphic embedding of G. For the same targets, we can further give lower bound estimates for the biLipschitz distortion of every embedding f : B ( n ) → X , where B ( n ) is the ball of radius n of a finitely generated nonabelian torsion-free nilpotent group G. We also prove an analogue of Bourgain's discretization theorem for Carnot groups and show that Carnot groups have nontrivial Markov convexity. These give the first examples of metric spaces that have nontrivial Markov convexity but cannot biLipschitzly embed into Banach spaces of nontrivial Markov convexity.
Spectral Feature Mapping with MIMIC Loss for Robust Speech Recognition

For the task of speech enhancement, local learning objectives are agnostic to phonetic structures helpful for speech recognition. We propose to add a global criterion to ensure de-noised speech is useful for downstream tasks like ASR. We first train a spectral classifier on clean speech to predict senone labels. Then, the spectral classifier is joined with our speech enhancer as a noisy speech recognizer. This model is taught to imitate the output of the spectral classifier alone on clean speech. This mimic loss is combined with the traditional local criterion to train the speech enhancer to produce de-noised speech. Feeding the de-noised speech to an off-the-shelf Kaldi training recipe for the CHiME- 2 corpus shows significant improvements in WER.
p-adic periods and derived de Rham cohomology

We construct p-adic period map using derived de Rham cohomology of Illusie and give a simple proof of Fontaine's C_{dR} conjecture.
Model-free imitation learning with policy optimization

In imitation learning, an agent learns how to behave in an environment with an unknown cost function by mimicking expert demonstrations. Existing imitation learning algorithms typically involve solving a sequence of planning or reinforcement learning problems. Such algorithms are therefore not directly applicable to large, high-dimensional environments, and their performance can significantly degrade if the planning problems are not solved to optimality. Under the apprenticeship learning formalism, we develop alternative model-free algorithms for finding a parameterized stochastic policy that performs at least as well as an expert policy on an unknown cost function, based on sample trajectories from the expert. Our approach, based on policy gradients, scales to large continuous environments with guaranteed convergence to local minima.
Lanczos-based Low-Rank Correction Method for Solving the Dyson Equation in Inhomogenous Dynamical Mean-Field Theory

Abstract Inhomogeneous dynamical mean-field theory has been employed to solve many interesting strongly interacting problems from transport in multilayered devices to the properties of ultracold atoms in a trap. The main computational step, especially for large systems, is the problem of calculating the inverse of a large sparse matrix to solve Dyson's equation and determine the local Green's function at each lattice site from the corresponding local self-energy. We present a new e_cient algorithm, the Lanczos-based low-rank algorithm, for the calculation of the inverse of a large sparse matrix which yields this local (imaginary time) Green's function. The Lanczos-based low-rank algorithm is based on a domain decomposition viewpoint, but avoids explicit calculation of Schur complements and relies instead on low-rank matrix approximations derived from the Lanczos algorithm, for solving the Dyson equation. We report at least a 25-fold improvement of performance compared to explicit decomposition (such as sparse LU) of the matrix inverse. We also report that scaling relative to matrix sizes, of the low-rank correction method on the one hand and domain decomposition methods on the other, are comparable.
Representation stability for families of linear subspace arrangements

Abstract Church–Ellenberg–Farb [8] used the language of FI-CHA to identify certain sequences of hyperplane arrangements with S n -actions that satisfy cohomological representation stability. Here we vastly extend their results, and define when a collection of arrangements is “finitely generated”. Using this notion we get stability results to: • General linear subspace arrangements, not necessarily of hyperplanes. • A wide class of group actions, replacing FI by a general category C. We show that the cohomology of such collections of arrangements satisfies a strong form of representation stability, with many concrete applications. For example, this implies that their Betti numbers are always given by certain polynomials. For this purpose we use the theory of representation stability for quite general classes of groups, developed in a [17] . We apply this theory to get classical cohomological stability of quotients of linear subspace arrangements with coefficients in certain constructible sheaves.
Micromagnetic simulations with periodic boundary conditions: Hard-soft nanocomposites

Abstract We developed a micromagnetic method for modeling magnetic systems with periodic boundary conditions along an arbitrary number of dimensions. The main feature is an adaptation of the Ewald summation technique for evaluation of long-range dipolar interactions. The method was applied to investigate the hysteresis process in hard-soft magnetic nanocomposites with various geometries. The dependence of the results on different micromagnetic parameters was studied. We found that for layered structures with an out-of-plane hard phase easy axis the hysteretic properties are very sensitive to the strength of the interlayer exchange coupling, as long as the spontaneous magnetization for the hard phase is significantly smaller than for the soft phase. The origin of this behavior was discussed. Additionally, we investigated the soft phase size optimizing the energy product of hard-soft nanocomposites.
Generalization of ERM in Stochastic Convex Optimization: The Dimension Strikes Back

In stochastic convex optimization the goal is to minimize a convex function $F(x) \doteq \E_{f\sim D}[f(x)]$ over a convex set $\K \subset \R^d$ where $D$ is some unknown distribution and each $f(\cdot)$ in the support of $D$ is convex over $\K$. The optimization is based on i.i.d.~samples $f^1,f^2,\ldots,f^n$ from $D$. A common approach to such problems is empirical risk minimization (ERM) that optimizes $F_S(x) \doteq \frac{1}{n}\sum_{i\leq n} f^i(x)$. Here we consider the question of how many samples are necessary for ERM to succeed and the closely related question of uniform convergence of $F_S$ to $F$ over $\K$. We demonstrate that in the standard $\ell_p/\ell_q$ setting of Lipschitz-bounded functions over a $\K$ of bounded radius, ERM requires sample size that scales linearly with the dimension $d$. This nearly matches standard upper bounds and improves on $\Omega(\log d)$ dependence proved for $\ell_2/\ell_2$ setting in (Shalev-Shwartz et al. 2009). In stark contrast, these problems can be solved using dimension-independent number of samples for $\ell_2/\ell_2$ setting and $\log d$ dependence for $\ell_1/\ell_\infty$ setting using other approaches. We also demonstrate that for a more general class of range-bounded (but not Lipschitz-bounded) stochastic convex programs an even stronger gap appears already in dimension 2.
Sums of products of polynomials in few variables: lower bounds and polynomial identity testing

We study the complexity of representing polynomials as a sum of products of polynomials in few variables. More precisely, we study representations of the form [EQUATION] such that each Qij is an arbitrary polynomial that depends on at most s variables. We prove the following results. Over fields of characteristic zero, for every constant μ such that 0 ≤ μ < 1, we give an explicit family of polynomials {PN}, where PN is of degree n in N = nO(1) variables, such that any representation of the above type for PN with s = Nμ requires [EQUATION]. This strengthens a recent result of Kayal and Saha [17] which showed similar lower bounds for the model of sums of products of linear forms in few variables. It is known that any asymptotic improvement in the exponent of the lower bounds (even for [EQUATION]) would separate VP and VNP [17]. We obtain a deterministic subexponential time blackbox polynomial identity testing (PIT) algorithm for circuits computed by the above model when T and the individual degree of each variable in P are at most logO(1) N and s ≤ Nμ for any constant μ < 1/2. We get quasipolynomial running time when s < logO(1) N. The PIT algorithm is obtained by combining our lower bounds with the hardness-randomness tradeoffs developed in [6, 14]. To the best of our knowledge, this is the first nontrivial PIT algorithm for this model (even for the case s = 2), and the first nontrivial PIT algorithm obtained from lower bounds for small depth circuits.
Geometric In-Hand Regrasp Planning: Alternating Optimization of Finger Gaits and In-Grasp Manipulation

This paper explores the problem of autonomous, in-hand regrasping-the problem of moving from an initial grasp on an object to a desired grasp using the dexterity of a robot's fingers. We propose a planner for this problem which alternates between finger gaiting, and in-grasp manipulation. Finger gaiting enables the robot to move a single finger to a new contact location on the object, while the remaining fingers stably hold the object. In-grasp manipulation moves the object to a new pose relative to the robot's palm, while maintaining the contact locations between the hand and object. Given the object's geometry (as a mesh), the hand's kinematic structure, and the initial and desired grasps, we plan a sequence of finger gaits and object reposing actions to reach the desired grasp without dropping the object. We propose an optimization based approach and report in-hand regrasping plans for 5 objects over 5 in-hand regrasp goals each. The plans generated by our planner are collision free and guarantee kinematic feasibility.
The combinatorics of directed planar trees

Abstract We give a geometric realization of the polyhedra governed by the structure of associative algebras with co-inner products, or more precisely, governed by directed planar trees. Our explicit realization of these polyhedra, which include the associahedra in a special case, shows in particular that these polyhedra are homeomorphic to balls. We also calculate the number of vertices of the lowest generalized associahedra, giving appropriate generalizations of the Catalan numbers.
On isomorphisms of certain functors for Cherednik algebras

Bezrukavnikov and Etingof introduced some functors between the cate- gories O for rational Cherednik algebras. Namely, they defined two induction functors Indb,indand two restriction functors Resb,res�. They conjectured that one has functor isomorphisms Indbind�,Resbres�. The goal of this paper is to prove this conjecture.
Learning FRAME models using CNN filters

The convolutional neural network (ConvNet or CNN) has proven to be very successful in many tasks such as those in computer vision. In this conceptual paper, we study the generative perspective of the discriminative CNN. In particular, we propose to learn the generative FRAME (Filters, Random field, And Maximum Entropy) model using the highly expressive filters pre-learned by the CNN at the convolutional layers. We show that the learning algorithm can generate realistic and rich object and texture patterns in natural scenes. We explain that each learned model corresponds to a new CNN unit at a layer above the layer of filters employed by the model. We further show that it is possible to learn a new layer of CNN units using a generative CNN model, which is a product of experts model, and the learning algorithm admits an EM interpretation with binary latent variables.
Resonance asymptotics for asymptotically hyperbolic manifolds with warped-product ends

We study the spectral theory of asymptotically hyperbolic manifolds with ends of warped-product type. Our main result is an upper bound on the resonance counting function with a geometric constant expressed in terms of the respective Weyl constants for the core of the manifold and the base manifold defining the ends.
Feature Selective Anchor-Free Module for Single-Shot Object Detection

We motivate and present feature selective anchor-free (FSAF) module, a simple and effective building block for single-shot object detectors. It can be plugged into single-shot detectors with feature pyramid structure. The FSAF module addresses two limitations brought up by the conventional anchor-based detection: 1) heuristic-guided feature selection; 2) overlap-based anchor sampling. The general concept of the FSAF module is online feature selection applied to the training of multi-level anchor-free branches. Specifically, an anchor-free branch is attached to each level of the feature pyramid, allowing box encoding and decoding in the anchor-free manner at an arbitrary level. During training, we dynamically assign each instance to the most suitable feature level. At the time of inference, the FSAF module can work independently or jointly with anchor-based branches. We instantiate this concept with simple implementations of anchor-free branches and online feature selection strategy. Experimental results on the COCO detection track show that our FSAF module performs better than anchor-based counterparts while being faster. When working jointly with anchor-based branches, the FSAF module robustly improves the baseline RetinaNet by a large margin under various settings, while introducing nearly free inference overhead. And the resulting best model can achieve a state-of-the-art 44.6% mAP, outperforming all existing single-shot detectors on COCO.
Counterexamples to the Local Solvability of Monge-Ampère Equations in the Plane

In this paper, we present C ∞ examples of degenerate hyperbolic and mixed type Monge-Ampere equations in the plane, which do not admit a local C 3 solution.
Low Complexity Antenna Selection for Low Target Rate Users in Dense Cloud Radio Access Networks

We propose a low complexity antenna selection algorithm for low target rate users in cloud radio access networks. The algorithm consists of two phases. In the first phase, each remote radio head (RRH) determines whether to be included in a candidate set by using a predefined selection threshold. In the second phase, RRHs are randomly selected within the candidate set made in the first phase. To analyze the performance of the proposed algorithm, we model RRHs’ and users’ locations by a homogeneous Poisson point process, whereby the signal-to-interference ratio (SIR) complementary cumulative distribution function is derived. By approximating the derived expression, an approximate optimum selection threshold that maximizes the SIR coverage probability is obtained. Using the obtained threshold, we characterize the performance of the algorithm in an asymptotic regime, where the RRH density goes to infinity. The obtained threshold is then modified depending on various algorithm options. A distinguishable feature of the proposed algorithm is that the algorithm complexity keeps constant independent to the RRH density, so that a user is able to connect to a network without heavy computation at baseband units.
Almost) practical tree codes

We consider the problem of stabilizing an unstable plant driven by bounded noise over a digital noisy communication link, a scenario at the heart of networked control. To stabilize such a plant, one needs real-time encoding and decoding with an error probability profile that decays exponentially with the decoding delay. The works of Schulman and Sahai over the past two decades have developed the notions of tree codes and anytime capacity, and provided the theoretical framework for studying such problems. Nonetheless, there has been little practical progress in this area due to the absence of explicit constructions of tree codes with efficient encoding and decoding algorithms. Recently, linear time-invariant tree codes were proposed to achieve the desired result under maximum-likelihood decoding. In this work, we take one more step towards practicality, by showing that these codes can be efficiently decoded using sequential decoding algorithms, up to some loss in performance (and with some practical complexity caveats). We supplement our theoretical results with numerical simulations that demonstrate the effectiveness of the decoder in a control system setting.
Exploiting Symmetry for Discrete-Time Reachability Computations

We present a method of computing backward reachable sets for nonlinear discrete-time control systems possessing continuous symmetries. The starting point is a dynamic game formulation of reachability analysis where control inputs aim to maintain the state variables within a target tube despite disturbances. Our method exploits symmetry to compute the reachable sets in a lower-dimensional space, enabling a significant computational speedup. To achieve this, we present a general method for symmetry reduction based on the Cartan frame, which simplifies the dynamic programming iteration without algebraic manipulation of the state update equations. We illustrate the results by computing a backward reachable set for a 6-D reach-avoid game of two Dubins vehicles.
Baryons in/and Lattice QCD

Anchoring our understanding of low-energy nuclear and hadronic physics to the fundamental theory of strong interactions, QCD, remains and outstanding challenge for physicists. Lattice QCD and chiral perturbation theory are the most powerful theoretical tools we have at our disposal to make this connection. These tools share a symbiotic relationship as chiral perturbation theory is used to understand the light quark mass dependence of observables, while lattice QCD is used to determine the values of the unknown operator coefficients appearing in the chiral Lagrangian. In this talk, I review our present understanding of select single baryon properties from lattice QCD and chiral perturbation theory, highlighting some of the challenges and discussing some unresolved puzzles.
The geometry of purely loxodromic subgroups of right-angled Artin groups

We prove that finitely generated purely loxodromic subgroups of a right-angled Artin group A(Γ) fulfill equivalent conditions that parallel characterizations of convex cocompactness in mapping class groups Mod(S). In particular, such subgroups are quasiconvex in A(Γ). In addition, we identify a milder condition for a finitely generated subgroup of A(Γ) that guarantees it is free, undistorted, and retains finite generation when intersected with A(Λ) for subgraphs Λ of Γ. These results have applications to both the study of convex cocompactness in Mod(S) and the way in which certain groups can embed in right-angled Artin groups.
A sharp lower bound on the polygonal isoperimetric deficit

It is shown that the isoperimetric deficit of a convex polygon P admits a lower bound in terms of the variance of the radii of P , the area of P , and the variance of the barycentric angles of P . The proof involves circulant matrix theory and a Taylor expansion of the deficit on a compact manifold.