cssi/SciSciGPT-SciSciNet huggingface dataset:
Practical Synthesis of Spirocyclic Bis-C,C-glycosides. Mechanistic Models in Explanation of Rearrangement Stereoselectivity and the Bifurcation of Reaction Pathways

The susceptibility of glycal-derived carbinols to acid-catalyzed ring expansion is described. In the systems prepared from cyclopentanone, Ferrier ionization precedes the pinacol-like Wagner−Meerwein shift, thermodynamic control operates, and high stereoselectivity is seen if a C(6) substituent is present. In contrast, the adducts to cyclobutanone exhibit release of ring strain under kinetically controlled conditions and intercept the oxonium species reversibly formed via direct proton transfer. The results show that the substituents positioned on the glycal ring have a pronounced influence on whether a chair-like or twist-boat transition state geometry is adopted primarily. The composite reaction profiles reveal for the first time the fundamental importance of exothermicity and of substitution in these spiro glycosidation reactions. Since optical activity is preserved in all instances, the utility of this chemistry for the synthesis of bis-C,C-glycosides and more complex oxacyclics appears promising.
Infrared and computational investigation of vanadium-substituted Keggin [PVnW12-nO40](n+3)- polyoxometallic anions.

This study investigates complex salts of [PW12O40]3-, [PVW11O40]4-, [PV2W10O40]5-, and [PV3W9O40]6- Keggin anions using Fourier transform infrared spectroscopy under ambient atmospheric and high-vacuum conditions and by computational methods. A detailed vibrational study suggests that the presence and amount of vanadium in these anions can be tested quickly and reliably with the help of infrared spectroscopy because the salts of these anions exhibit distinctly different infrared absorption signatures (particularly in the 1025−1250 cm-1 region, where the P−O stretch is surrounded by a set of complex vibrations involving V−O and W−O bonds). Investigation of these salts with different countercations suggests that the overall appearance of the spectra, and thus the ability to use infrared as a diagnostic tool to identify the presence and number of vanadium atoms in Keggin structure anions, is not affected significantly. Last, it is shown that all the structures investigated are extremely stable across a wide ...
An Ab Initio Study of the Geometry and Rotational Barrier of 4- Phenylimidazole

The molecular design of several synthetic artificial enzymes, which mimic the action of the serine proteaseα-chymotrypsin, incorporates the phenylimidazole molecular fragment to play the role of the His-57 residue in the native enzyme active site. Study of these artificial enzymes by molecular modeling techniques requires accurate torsional force field parameters for the phenylimidazole interring bond. This, in turn, requires accurate characterization of the barrier to rotation around this bond. Previous semiempirical calculations of this rotational barrier have neglected geometry optimization of the molecule at the points along the rotational pathway. The 4-phenylimidazole rotational barrier (5.6 kcal mol−1] presented here was obtained by full ab initio geometry optimization at the 3–21G level at each of the points along the rotational pathway.
Secondary–secondary diamine catalysts for the enantioselective Michael addition of cyclic ketones to nitroalkenes

Abstract Secondary–secondary diamines derived from S-proline are efficient catalysts for the ketone–nitroalkene Michael addition reaction. The stereoselectivity of the Michael addition is dependant on the pKa of the N-substituted aminomethyl pendant in these diamines. N′-Aryl aminomethyl pyrrolidines provide γ-nitroketones with moderate to good enantiomeric excess (65–92%). Removal of the hydrogen-bond donor group by N-methylation results in a dramatic reduction of enantioselectivity (average ee 6%).
Enantioselective synthesis of cyclic allylboronates by Mo-catalyzed asymmetric ring-closing metathesis (ARCM). A one-pot protocol for net catalytic enantioselective cross metathesis

Mo-catalyzed asymmetric ring-closing metathesis (ARCM) reactions are used to synthesize cyclic allylboronates of high optical purity (89% ee to >98% ee). A one-pot procedure involving formation of allylboronates, Mo-catalyzed ARCM and functionalization of the optically enriched cyclic allylboronates constitutes net asymmetric cross metathesis (ACM). Structural modification of ARCM products include reactions with aldehydes to afford optically enriched compounds that bear quaternary carbon centers with excellent diastereoselectivity. These studies emphasize the significance of the availability of chiral Mo-based complex as a class of chiral metathesis catalysts that frequently complement one another in terms of reactivity and selectivity.
Paradigm Shift in Sensorimotor Control Research and Brain Machine Interface Control: The Influence of Context on Sensorimotor Representations.

Neural activity in the primary motor cortex (M1) is known to correlate with movement related variables including kinematics and dynamics. Our recent work, which we believe will lead to a paradigm shift in sensorimotor research, has shown that in addition to these movement related variables, activity in M1, and the primary somatosensory cortex (S1), are also modulated by context, such as value, during both active movement and movement observation. Here we expand on the investigation of reward modulation in M1, showing that reward level changes the neural tuning function of M1 units to both kinematic as well as dynamic related variables. In addition, we show that this reward-modulated activity is present during brain machine interface (BMI) control. We suggest that by taking into account these context dependencies of M1 modulation, we can produce more robust BMIs. Toward this goal, we demonstrate that we can classify reward expectation from M1 on a movement-by-movement basis under BMI control and use this to gate multiple linear BMI decoders toward improved offline performance. These findings demonstrate that it is possible and meaningful to design a more accurate BMI decoder that takes reward and context into consideration. Our next step in this development will be to incorporate this gating system, or a continuous variant of it, into online BMI performance.
Fallen Pillars: The past, present, and future population dynamics of a rare, specialist coral-algal symbiosis

With ongoing changes in climate, rare and ecologically specialized species are at increased risk of extinction. In sessile foundation fauna that reproduce asexually via fragmentation of existing colonies, the number of colonies does not reflect the number of genets and thus can obscure genotypic diversity. Colonies that are the product of fragmentation are not visually distinguishable from colonies that stem from sexual recruits. For this reason, molecular markers are necessary to assess genotypic variation and population structure in clonal organisms such as reef-building corals and their endosymbiotic dinoflagellates. For the rare Caribbean pillar coral, Dendrogyra cylindrus, and its endosymbiotic dinoflagellate, Breviolum dendrogyrum, we use de novo microsatellite markers to infer past demographic changes, describe modern population structure, and quantify the frequency of asexual reproduction. Our analyses show that D. cylindrus comprises three distinct populations across the Greater Caribbean whereas the symbiont could be differentiated into four populations, indicating barriers to gene flow differ between host and symbiont. In Florida, host and symbiont populations reproduced mainly asexually, yielding lower genotypic diversity than predicted from census size. When multiple coral ramets were present, they often associated with the same clonal strain of B. dendrogyrum, pointing to the high fidelity of this relationship. Models of past demographic events revealed no evidence for historical changes in population sizes, consistent with the paleontological record of D. cylindrus indicating it has been rare for hundreds of thousands of years. The most recent global thermal stress event triggered a severe disease outbreak among D. cylindrus in Florida, resulting in a severe population decline. Projections indicate a high likelihood that this species will become extinct in the Northern Greater Caribbean within a few decades. The ecosystem consequences of losing rare coral species and their symbionts with increasingly frequent extreme warming events are not known but require urgent study.
An Asymmetric Route to the Conanine BCDE Ring System. A Formal Total Synthesis of (+)-Conessine

The first enantioselective synthesis of the known (+)-conessine precursor (+)-benzohydrindan 23 from the chiral nonracemic bicyclic lactam 1 is described. The key transformation was the highly diastereoselective (3 + 2) cycloaddition of azomethine ylide 11a to lactam 7 in order to construct the pyrrolidine E ring system at any early stage in the synthesis. The requisite pyrrolidine methyl group at C-21 was stereoselectively installed late in the synthesis by lithiation of N-Boc-pyrrolidine intermediate 20 with sec-BuLi/TMEDA followed by quenching at −90 °C with iodomethane, furnishing the tetracyclic pyrrolidine 21. Reduction of t-Boc 21 with lithium aluminum hydride affords (+)-N-methyl tetracycle 23 in a concise 13-step synthesis from 1.
Objective versus Self‐Reported Energy Intake Changes During Low‐Carbohydrate and Low‐Fat Diets

Objective This study aimed to compare self-reported with objective measurements of energy intake changes (∆EI) during a 1-year weight-loss intervention with subjects randomized to low-carbohydrate versus low-fat diets. Methods Repeated body weight measurements were used as inputs to an objective mathematical model to calculate ∆EIModel and to compare with self-reported energy intake changes assessed by repeated 24-hour recalls (∆EIRecall ). Results ∆EIRecall indicated a relatively persistent state of calorie restriction of ~500 to 600 kcal/d at 3, 6, and 12 months with no significant differences between the diets. ∆EIModel demonstrated large early decreases in calorie intake > 800 kcal/d followed by an exponential return to ~100 kcal/d below baseline at the end of the year. Accounting for self-reported physical activities did not materially affect the results. Discrepancies between ∆EIModel and ∆EIRecall became progressively greater over time. The low-carbohydrate diet resulted in ∆EIModel that was 162 ± 53 kcal/d lower than the low-fat diet over the first 3 months (P = 0.002), but no significant diet differences were found thereafter. Conclusions Self-reported ∆EI measurements were inaccurate. Model-based calculations of ∆EI found that instructions to follow the low-carbohydrate diet resulted in greater calorie restriction than the low-fat diet in the early phases of the intervention, but these diet differences were not sustained.
A mild, chemoselective, one-pot synthesis of δ-keto α-cyano esters by organocatalysis

Abstract A sequential condensation of α-cyano esters, aldehydes, and ketones with catalytic amount of pyrrolidine/HOAc at room temperature has been developed. This method offers a chemoselective, one-pot cascade access to δ-keto α-cyano esters with moderate to good yields under mild conditions.
Lewis acid-promoted carbonyl addition of lithium (α-carbalkoxyvinyl)cuprates to aldehydes provides a novel asymmetric synthesis of β,β-disubstituted α-(hydroxyalkyl)acrylates

Abstract A new anionic addition process has been developed for the asymmetric synthesis of unusual Baylis-Hillman adducts, β,β-disubstituted α-(hydroxyalkyl)acrylates. The new process involves conjugate addition of R 2 CuLi to β-substituted α,β-acetylenic ester to give lithium (α-carbalkoxyvinyl)cuprate which was then subjected to the carbonyl addition to aldehyde promoted by Et 2 AlCl. Modest to good diastereoselectivity (50.0 – 87.7 % de) has been obtained by using (1R,2S,5R)-(−)-menthol as the chiral auxiliary (59.0 – 94.0 % yield). The absolute configuration was unambiguously assigned by transforming the product to methyl (R)-α-methoxyphenylacetate.
Identification of an impurity in synthetically prepared GAZT: 4″,5″-dehydro-GAZT

A minor impurity was recorded by hplc during the final purification of synthetically prepared samples of the 5′-0-glucuronide of azidothymidine (GAZT). Following isolation of a small quantity of this impurity by hplc, elucidation of the structure was undertaken. A combination of two-dimensional nmr methods in conjunction with infrared spectroscopy and mass spectrometry were utilized to unequivocally identify the impurity as the 4″,5″-dehydro-5′-O-glucuronide of AZT (DGAZT).
Efficient formation of novel and versatile building blocks from mucohalic acids: new substitute for tetronic acid and γ-alkylidenebutenolide

Abstract Novel and useful building blocks were synthesized efficiently by DABCO mediated highly selective dehalogenation of Knoevenagel aldol adducts of mucochloric acid and mucobromic acid. These new compounds were found to undergo palladium catalyzed C–C bond forming reactions (Suzuki and Sonogashira cross-coupling) in high yields.
Enantioenriched acid, ester, and ketone β-phenyl homoenolate synthetic equivalents from N-Boc-N-(p-methoxyphenyl)cinnamylamine

Abstract Oxidation of the β-substituted highly enantioenriched aldehydes obtained by hydrolysis of the 3,3-disubstituted enecarbamates affords enantioenriched β-substituted acids and esters. Lithiation of enantioenriched 3,3-disubstituted enecarbamates and subsequent reaction with electrophiles provides vinylically substituted enecarbamates. The use of benzyl and alkyl halide electrophiles affords α-substituted enecarbamates, which can be hydrolyzed to provide enantioenriched β-substituted ketones. Reaction of the lithiated intermediate with ketones affords oxazolidinones, which can be reductively ring-opened with DIBAL and hydrolyzed to provide enantioenriched β-substituted, α′-hydroxy ketones. These transformations demonstrate that the enantioselective lithiation of N -Boc- N -( p -methoxyphenyl)cinnamylamine provides a reactive intermediate which can be a ketone, acid, or ester homoenolate synthon.
Asymmetric Allylation, Crotylation, and Cinnamylation of N-Heteroaryl Hydrazones

A new class of N-heteroaryl hydrazones has been developed as an alternative to N-acylhydrazones and 2-aminophenol-derived imines in asymmetric allylation, crotylation, and cinnamylation reactions with chiral allylchlorosilanes. The hydrazones are readily and inexpensively prepared, perform well in the allylation chemistry, and more importantly, the product hydrazides may be smoothly reduced by Pd(OH)2-catalyzed hydrogenation to reveal the corresponding amine products.
Cation−Cation Interactions in Sr5(UO2)20(UO6)2O16(OH)6(H2O)6 and Cs(UO2)9U3O16(OH)5

Two novel U6+ compounds, Sr5(UO2)20(UO6)2O16(OH)6(H2O)6 (SrFm) and Cs(UO2)9U3O16(OH)5 (CsFm), have been synthesized by mild hydrothermal reactions. The structures of SrFm (orthorhombic, C2221, a = 11.668(1), b = 21.065 (3), c = 13.273 A, V = 3532.5(1) A3, Z = 2) and CsFm (trigonal, R3c, a = 11.395(2), c = 43.722(7) A, V = 4916.7(1) A3, Z = 6) are rare examples of uranyl compounds that contain cation-cation interactions where an O atom of one uranyl ion is directly linked to another uranyl ion. Both structures are complex frameworks. SrFm contains sheets of polyhedra that are linked through cation-cation interactions with uranyl ions located between the sheets. CsFm possesses an unusually complex framework of vertex- and edge-sharing U6+ polyhedra that incorporates cation-cation interactions.
Zeolite: An efficient catalyst for the synthesis of various heterocyclic compounds

Abstract A novel heterogeneous catalytic method to synthesize various heterocyclic compounds of biological interest, aminobenzisothiazole [2a-h] and 1,3-thiazine derivatives [4, 6] , using an environmentally attractive solid catalyst, zeolite, is described.
Superelectrophiles in heterocyclic ring-forming reactions

Superelectrophiles are multiply charged cationic species which may exhibit remarkable reactivities towards weak nucleophiles. Since their discovery in the 1970s, many novel synthetic methodologies have been developed using superelectrophiles. In the following Account, superelectrophilic ring-forming reaction will be examined, specifically those reaction which produce heterocyclic systems.
Microsatellite primer development for the invasive perennial herb Gypsophila paniculata (Caryophyllaceae).

Premise of the Study Gypsophila paniculata (baby's breath; Caryophyllaceae) is a herbaceous perennial that has invaded much of northern and western United States and Canada, outcompeting and crowding out native and endemic species. Microsatellite primers were developed to analyze the genetic structure of invasive populations. Methods and Results We identified 16 polymorphic nuclear microsatellite loci for G. paniculata out of 73 loci that successfully amplified from a primer library created using Illumina sequencing technology. Microsatellite primers were developed to amplify di-, tri-, and tetranucleotide repeats and tested in three invasive populations in Michigan. Conclusions These markers will be useful in characterizing the genetic structure of invasive populations throughout North America to aid targeted management efforts, and in native Eurasian populations to better understand invasion history. Five of these developed primers also amplified in G. elegans.
Accuracy of robotic coil positioning during transcranial magnetic stimulation.

Objective Robotic positioning systems for transcranial magnetic stimulation (TMS) promise improved accuracy and stability of coil placement, but there is limited data on their performance. Investigate the usability, accuracy, and limitations of robotic coil placement with a commercial system, ANT Neuro, in a TMS study. Approach 21 subjects underwent a total of 79 TMS sessions corresponding to 160 hours under robotic coil control. Coil position and orientation were monitored concurrently through an additional neuronavigation system. Main results Robot setup took on average 14.5 min. The robot achieved low position and orientation error with median 3.54 mm (overall, 1.34 mm without coil-head spacing) and 3.48°. The error increased over time at a rate of 0.4%/minute for both position and orientation. Significance Robotic TMS systems can provide accurate and stable coil position and orientation in long TMS sessions. Lack of pressure feedback and of manual adjustment of all coil degrees of freedom were limitations of this robotic system.
Transient Thresholding: A Mechanism Enabling Noncooperative Transcriptional Circuitry to Form a Switch

Threshold generation in fate-selection circuits is often achieved through deterministic bistability, which requires cooperativity (i.e., nonlinear activation) and associated hysteresis. However, the Tat positive-feedback loop that controls HIV’s fate decision between replication and proviral latency lacks self-cooperativity and deterministic bistability. Absent cooperativity, it is unclear how HIV can temporarily remain in an off-state long enough for the kinetically slower epigenetic silencing mechanisms to act—expression fluctuations should rapidly trigger active positive feedback and replication, precluding establishment of latency. Here, using flow cytometry and single-cell imaging, we find that the Tat circuit exhibits a transient activation threshold. This threshold largely disappears after ∼40 h—accounting for the lack of deterministic bistability—and promoter activation shortens the lifetime of this transient threshold. Continuous differential equation models do not recapitulate this phenomenon. However, chemical reaction (master equation) models where the transcriptional transactivator and promoter toggle between inactive and active states can recapitulate the phenomenon because they intrinsically create a single-molecule threshold transiently requiring excess molecules in the inactive state to achieve at least one molecule (rather than a continuous fractional value) in the active state. Given the widespread nature of promoter toggling and transcription factor modifications, transient thresholds may be a general feature of inducible promoters.
Hydroxylammonium Nitrate Species in a Monopropellant Electrospray Plume

A mixture of 1-ethyl-3-methylimidazolium ethyl sulfate ([Emim][EtSO4]) and hydroxylammonium nitrate (HAN) is an energetic monopropellant potentially suitable in a multimode chemical-electric microt...
Is There Information Content in Information Acquisition

ABSTRACT In this study, we examine whether investors' actions to acquire accounting information are predictive of future firm performance because these actions partially reveal investors' private e...
Proper homotopy types and Z-boundaries of spaces admitting geometric group actions

Abstract We extend several techniques and theorems from geometric group theory so they apply to geometric actions on arbitrary proper metric ARs (absolute retracts). Previous versions often required actions on CW complexes, manifolds, or proper CAT(0) spaces, or else included a finite-dimensionality hypothesis. We remove those requirements, providing proofs that simultaneously cover all of the usual variety of spaces. A second way that we generalize earlier results is by eliminating a freeness requirement often placed on the group actions. In doing so, we allow for groups with torsion. The main theorems are new in that they generalize results found in the literature, but a significant aim is expository. Toward that end, brief but reasonably comprehensive introductions to the theories of ANRs (absolute neighborhood retracts) and Z -sets are included, as well as a much shorter introduction to shape theory. Here is a sampling of the theorems proved here. Theorem. If quasi-isometric groups G and H act geometrically on proper metric ARs X and Y , resp., then X is proper homotopy equivalent to Y . Theorem. If quasi-isometric groups G and H act geometrically on proper metric ARs X and Y , resp., and Y can be compactified to a Z -structure Y ¯ , Z for H , then the same boundary can be added to X to obtain a Z -structure for G . Theorem. If quasi-isometric groups G and H admit Z -structures X ¯ , Z 1 and Y ¯ , Z 2 , resp., then Z 1 and Z 2 are shape equivalent.
Categorical Lagrangian Grassmannians and Brauer–Picard groups of pointed fusion categories

Abstract We analyze the action of the Brauer–Picard group of a pointed fusion category on the set of Lagrangian subcategories of its center. Using this action we compute the Brauer–Picard groups of pointed fusion categories associated to several classical finite groups. As an application, we construct examples of weakly group-theoretical fusion categories.
Formulas for Chebotarev densities of Galois extensions of number fields

We generalize the Chebotarev density formulas of Dawsey (Res Number Theory 3:27, 2017) and Alladi (J Number Theory 9:436–451, 1977) to the setting of arbitrary finite Galois extensions of number fields L / K. In particular, if \(C \subset G = {{\mathrm{Gal}}}(L/K)\) is a conjugacy class, then we establish that the Chebotarev density is the following limit of partial sums of ideals of K: $$\begin{aligned} -\lim _{X\rightarrow \infty } \sum _{\begin{array}{c} 2\le N(I)\le X \\ I \in S(L/K; C) \end{array}} \frac{\mu _K(I)}{N(I)} = \frac{|C|}{|G|}, \end{aligned}$$ where \(\mu _K(I)\) denotes the generalized Mobius function and S(L / K; C) is the set of ideals \(I\subset \mathcal {O}_K\) such that I has a unique prime divisor \(\mathfrak {p}\) of minimal norm and the Artin symbol \(\left[ \frac{L/K}{\mathfrak {p}}\right] \) is C. To obtain this formula, we generalize several results from classical analytic number theory, as well as Alladi’s concept of duality for minimal and maximal prime divisors, to the setting of ideals in number fields.
Signal Recovery on Graphs: Fundamental Limits of Sampling Strategies

This paper builds theoretical foundations for the recovery of a newly proposed class of smooth graph signals, approximately bandlimited graph signals, under three sampling strategies: uniform sampling, experimentally designed sampling, and active sampling. We then state minimax lower bounds on the maximum risk for the approximately bandlimited class under these three sampling strategies and show that active sampling cannot fundamentally outperform experimentally designed sampling. We propose a recovery strategy to compare uniform sampling with experimentally designed sampling. As the proposed recovery strategy lends itself well to statistical analysis, we derive the exact mean square error for each sampling strategy. To study convergence rates, we introduce two types of graphs and find that 1) the proposed recovery strategy achieves the optimal rates; and 2) the experimentally designed sampling fundamentally outperforms uniform sampling for Type-2 class of graphs. To validate our proposed recovery strategy, we test it on five specific graphs: a ring graph with $k$ nearest neighbors, an Erdős–Renyi graph, a random geometric graph, a small-world graph, and a power-law graph and find that experimental results match the proposed theory well. This paper also presents a comprehensive explanation for when and why sampling for semi-supervised learning with graphs works.
Deep Reinforcement Learning for Resource Allocation in V2V Communications

In this article, we develop a decentralized resource allocation mechanism for vehicle-to- vehicle (V2V) communications based on deep reinforcement learning. Each V2V link is supported by an autonomous "agent", which makes its decisions to find the optimal sub-band and power level for transmission without requiring or having to wait for global information. Hence, the proposed method is decentralized, with minimum transmission overhead. From the simulation results, each agent can effectively learn how to satisfy the stringent latency constraints on V2V links while minimizing the interference to vehicle-to-infrastructure (V2I) communications.
OSTSC: Over Sampling for Time Series Classification in R

The OSTSC package is a powerful oversampling approach for classifying univariant, but multinomial time series data in R. This vignette provides a brief overview of the oversampling methodology implemented by the package. A tutorial of the OSTSC package is provided. We begin by providing three test cases for the user to quickly validate the functionality in the package. To demonstrate the performance impact of OSTSC, we then provide two medium size imbalanced time series datasets. Each example applies a TensorFlow implementation of a Long Short-Term Memory (LSTM) classifier - a type of a Recurrent Neural Network (RNN) classifier - to imbalanced time series. The classifier performance is compared with and without oversampling. Finally, larger versions of these two datasets are evaluated to demonstrate the scalability of the package. The examples demonstrate that the OSTSC package improves the performance of RNN classifiers applied to highly imbalanced time series data. In particular, OSTSC is observed to increase the AUC of LSTM from 0.543 to 0.784 on a high frequency trading dataset consisting of 30,000 time series observations.
Stable Optimal Control and Semicontractive Dynamic Programming

We consider discrete-time infinite horizon deterministic optimal control problems with nonnegative cost per stage, and a destination that is cost free and absorbing. The classical linear-quadratic regulator problem is a special case. Our assumptions are very general, and allow the possibility that the optimal policy may not be stabilizing the system, e.g., may not reach the destination either asymptotically or in a finite number of steps. We introduce a new unifying notion of stable feedback policy, based on perturbation of the cost per stage, which in addition to implying convergence of the generated states to the destination, quantifies the speed of convergence. We consider the properties of two distinct cost functions: $J^*$, the overall optimal, and $\hat J$, the restricted optimal over just the stable policies. Different classes of stable policies (with different speeds of convergence) may yield different values of $\hat J$. We show that for any class of stable policies, $\hat J$ is a solution of Bel...
Note on the Union-Closed Sets Conjecture

The union-closed sets conjecture states that if a finite family of sets $\mathcal{A} \neq \{\varnothing\}$ is union-closed, then there is an element which belongs to at least half the sets in $\mathcal{A}$. In 2001, D. Reimer showed that the average set size of a union-closed family, $\mathcal{A}$, is at least $\frac{1}{2} \log_2 |\mathcal{A}|$. In order to do so, he showed that all union-closed families satisfy a particular condition, which in turn implies the preceding bound. Here, answering a question raised in the context of T. Gowers' polymath project on the union-closed sets conjecture, we show that Reimer's condition alone is not enough to imply that there is an element in at least half the sets.
Fourier-stable subrings in the Chow rings of abelian varieties

We study subrings in the Chow ring $\CH^*(A)_{\Q}$ of an abelian variety $A$, stable under the Fourier transform with respect to an arbitrary polarization. We prove that by taking Pontryagin products of classes of dimension $\le 1$ one gets such a subring. We also show how to construct finite-dimensional Fourier-stable subrings in $\CH^*(A)_{\Q}$. Another result concerns the relation between the Pontryagin product and the usual product on the $\CH^*(A)_{\Q}$. We prove that the operator of the usual product with a cycle is a differential operator with respect to the Pontryagin product and compute its order in terms of the Beauville's decomposition of $\CH^*(A)_{\Q}$.
MOCCA: mirrored convex/concave optimization for nonconvex composite functions

Many optimization problems arising in high-dimensional statistics decompose naturally into a sum of several terms, where the individual terms are relatively simple but the composite objective function can only be optimized with iterative algorithms. In this paper, we are interested in optimization problems of the form F(Kx) + G(x), where K is a fixed linear transformation, while F and G are functions that may be nonconvex and/or nondifferentiable. In particular, if either of the terms are nonconvex, existing alternating minimization techniques may fail to converge; other types of existing approaches may instead be unable to handle nondifferentiability. We propose the mocca (mirrored convex/concave) algorithm, a primal/dual optimization approach that takes a local convex approximation to each term at every iteration. Inspired by optimization problems arising in computed tomography (CT) imaging, this algorithm can handle a range of nonconvex composite optimization problems, and offers theoretical guarantees for convergence when the overall problem is approximately convex (that is, any concavity in one term is balanced out by convexity in the other term). Empirical results show fast convergence for several structured signal recovery problems.
Semi-supervised convolutional neural networks for human activity recognition

Labeled data used for training activity recognition classifiers are usually limited in terms of size and diversity. Thus, the learned model may not generalize well when used in real-world use cases. Semi-supervised learning augments labeled examples with unlabeled examples, often resulting in improved performance. However, the semi-supervised methods studied in the activity recognition literatures assume that feature engineering is already done. In this paper, we lift this assumption and present two semi-supervised methods based on convolutional neural networks (CNNs) to learn discriminative hidden features. Our semi-supervised CNNs learn from both labeled and unlabeled data while also performing feature learning on raw sensor data. In experiments on three real world datasets, we show that our CNNs outperform supervised methods and traditional semi-supervised learning methods by up to 18% in mean F1-score (F m ).
An Improved Convergence Analysis of Cyclic Block Coordinate Descent-type Methods for Strongly Convex Minimization

The cyclic block coordinate descent-type (CBCD-type) methods have shown remarkable computational performance for solving strongly convex minimization problems. Typical applications include many popular statistical machine learning methods such as elastic-net regression, ridge penalized logistic regression, and sparse additive regression. Existing optimization literature has shown that the CBCD-type methods attain iteration complexity of $O(p\cdot\log(1/\epsilon))$, where $\epsilon$ is a pre-specified accuracy of the objective value, and $p$ is the number of blocks. However, such iteration complexity explicitly depends on $p$, and therefore is at least $p$ times worse than those of gradient descent methods. To bridge this theoretical gap, we propose an improved convergence analysis for the CBCD-type methods. In particular, we first show that for a family of quadratic minimization problems, the iteration complexity of the CBCD-type methods matches that of the gradient descent methods in term of dependency on $p$ (up to a $\log^2 p$ factor). Thus our complexity bounds are sharper than the existing bounds by at least a factor of $p/\log^2p$. We also provide a lower bound to confirm that our improved complexity bounds are tight (up to a $\log^2 p$ factor) if the largest and smallest eigenvalues of the Hessian matrix do not scale with $p$. Finally, we generalize our analysis to other strongly convex minimization problems beyond quadratic ones
Loops in SU(2) and factorization

We discuss analytic issues associated with a refinement of triangular factorization for the loop group of SU(2). This factorization is of interest because (1) Toeplitz determinants factor in the associated coordinates, and (2) the factorization is intimately related to the critical degree of smoothness for loops, W1/2,L2.
An efficient adaptive sparse grid collocation method through derivative estimation

Abstract For uncertainty propagation of highly complex and/or nonlinear problems, one must resort to sample-based non-intrusive approaches (Le Maitre and Knio, 2010). In such cases, minimizing the number of function evaluations required to evaluate the response surface is of paramount importance. Sparse grid approaches have proven effective in reducing the number of sample evaluations. For example, the discrete projection collocation method has the notable feature of exhibiting fast convergence rates when approximating smooth functions; however, it lacks the ability to accurately and efficiently track response functions that exhibit fluctuations, abrupt changes or discontinuities in very localized regions of the input domain. On the other hand, the piecewise linear collocation interpolation approach can track these localized variations in the response surface efficiently, but it converges slowly in the smooth regions. The proposed methodology, building on an existing work on adaptive hierarchical sparse grid collocation algorithm (Ma and Zabaras, 2009), is able to track localized behavior while also avoiding unnecessary function evaluations in smoother regions of the stochastic space by using a finite difference based one-dimensional derivative evaluation technique in all the dimensions. This derivative evaluation technique leads to faster convergence in the smoother regions than what is achieved in the existing collocation interpolation approaches. Illustrative examples show that this method is well suited to high-dimensional stochastic problems, and that stochastic elliptic problems with stochastic dimension as high as 100 can be dealt with effectively.
Effects of sapphire nitridation and growth temperature on the epitaxial growth of hexagonal boron nitride on sapphire

This paper reports on the epitaxial growth of hexagonal boron nitride (hBN) films on sapphire substrates in a cold wall chemical vapor deposition (CVD) system where different sapphire nitridation and hBN growth temperatures were employed. A thin and amorphous nitridated layer was formed at a low temperature (850 °C), which enabled subsequent epitaxial hBN growth at 1350 °C. The influences of the sapphire nitridation temperature and the growth temperature on the film quality were analyzed by x-ray diffraction (XRD) measurements. Higher than optimum nitridation and growth temperatures improve the crystalline quality of the nitridated layer, but does not favor the epitaxial growth of hBN. hBN films grown at the optimum conditions exhibit the c-lattice constant of 6.66 A from the XRD θ–2θ scan and the characteristic in plane stretching vibration at 1370.5 cm−1 from Raman spectroscopy. X-ray photoelectron spectroscopy analysis confirmed the formation of stoichiometric hBN films with excellent uniformity.
Representation growth in positive characteristic and conjugacy classes of maximal subgroups

We study the representation growth of alternating and symmetric groups in positive characteristic and restricted representation growth for the finite groups of Lie type. We show that the number of representations of dimension at most n is bounded by a low-degree polynomial in n. As a consequence, we show that the number of conjugacy classes of maximal subgroups of a finite almost simple group G is at most O((log|G|)3).
A localization theorem and boundary regularity for a class of degenerate Monge–Ampere equations

Abstract We consider degenerate Monge–Ampere equations of the type det D 2 u = f in Ω , f ∼ d ∂ Ω α near ∂ Ω , where d ∂ Ω represents the distance to the boundary of the domain Ω and α > 0 is a positive power. We obtain C 2 estimates at the boundary under natural conditions on the boundary data and the right-hand side. Similar estimates in two dimensions were obtained by J.X. Hong, G. Huang and W. Wang in [3] .
Accurate Qubit Control with Single Flux Quantum Pulses

A longstanding goal of quantum-computer architecture is to integrate control circuitry in a fault-tolerant and compact manner that will facilitate future scalable designs. In this paper, authors propose using resonant trains of single flux quantum pulses to produce fidelities in excess of 99.9% for 20-ns gate times. The pulses provide one sharp kick per qubit oscillation period, analogous to pumping up a rider on a swing by giving one short push per cycle.
Planning with Verbal Communication for Human-Robot Collaboration

Human collaborators coordinate effectively their actions through both verbal and non-verbal communication. We believe that the the same should hold for human-robot teams. We propose a formalism that enables a robot to decide optimally between taking a physical action toward task completion and issuing an utterance to the human teammate. We focus on two types of utterances: verbal commands, where the robot asks the human to take a physical action, and state-conveying actions, where the robot informs the human about its internal state, which captures the information that the robot uses in its decision making. Human subject experiments show that enabling the robot to issue verbal commands is the most effective form of communicating objectives, while retaining user trust in the robot. Communicating information about the robot’s state should be done judiciously, since many participants questioned the truthfulness of the robot statements when the robot did not provide sufficient explanation about its actions.
Investigation of Using Disentangled and Interpretable Representations for One-shot Cross-lingual Voice Conversion.

We study the problem of cross-lingual voice conversion in non-parallel speech corpora and one-shot learning setting. Most prior work require either parallel speech corpora or enough amount of training data from a target speaker. However, we convert an arbitrary sentences of an arbitrary source speaker to target speaker's given only one target speaker training utterance. To achieve this, we formulate the problem as learning disentangled speaker-specific and context-specific representations and follow the idea of [1] which uses Factorized Hierarchical Variational Autoencoder (FHVAE). After training FHVAE on multi-speaker training data, given arbitrary source and target speakers' utterance, we estimate those latent representations and then reconstruct the desired utterance of converted voice to that of target speaker. We investigate the effectiveness of the approach by conducting voice conversion experiments with varying size of training utterances and it was able to achieve reasonable performance with even just one training utterance. We also examine the speech representation and show that World vocoder outperforms Short-time Fourier Transform (STFT) used in [1]. Finally, in the subjective tests, for one language and cross-lingual voice conversion, our approach achieved significantly better or comparable results compared to VAE-STFT and GMM baselines in speech quality and similarity.
Quantum gravity: a quantum-first approach

A “quantum-first” approach to gravity is described, where rather than quantizing gen- eral relativity, one seeks to formulate the physics of gravity within a quantum-mechanical framework with suitably general postulates. Important guides are the need for appropri- ate mathematical structure on Hilbert space, and correspondence with general relativity and quantum field theory in weak-gravity situations. A basic physical question is that of “Einstein separability:” how to define mutually independent subsystems, e.g. through localization. Standard answers via tensor products or operator algebras conflict with prop- erties of gravity, as is seen in the correspondence limit; this connects with discussions of “soft hair.” Instead, gravitational behavior suggests a networked Hilbert space structure. This structure plus unitarity provide important clues towards a quantum formulation of gravity.
Scattering for wave maps exterior to a ball

Abstract We consider 1-equivariant wave maps from R t × ( R x 3 ∖ B ) → S 3 where B is a ball centered at 0, and ∂ B gets mapped to a fixed point on S 3 . We show that 1-equivariant maps of degree zero scatter to zero irrespective of their energy. For positive degrees, we prove asymptotic stability of the unique harmonic maps in the energy class determined by the degree.
Action of Clifford Algebra on the Space of Sequences of Transfer Operators

We deduce from a determinant identity on quantum transfer matrices of generalized quantum integrable spin chain model their generating functions. We construct the isomorphism of Clifford algebra modules of sequences of transfer matrices and the boson space of symmetric functions. As an application, tau-functions of transfer matrices immediately arise from classical tau-functions of symmetric functions.
The homogeneous spectrum of Milnor–Witt K-theory

Abstract For any field F (of characteristic not equal to 2), we determine the Zariski spectrum of homogeneous prime ideals in K ⁎ M W ( F ) , the Milnor–Witt K-theory ring of F. As a corollary, we recover Lorenz and Leicht's classical result on prime ideals in the Witt ring of F. Our computation can be seen as a first step in Balmer's program for studying the tensor triangular geometry of the stable motivic homotopy category.
Rational group actions on affine PI-algebras

Let R be an affine PI-algebra over an algebraically closed field k and let G be an affine algebraic k-group that acts rationally by algebra automorphisms on R.F orR prime and G a torus, we show that R has only finitely many G-prime ideals if and only if the action of G on the centre of R is multiplicity free. This extends a standard result on affine algebraic G-varieties. Under suitable hypotheses on R and G, we also prove a PI-version of a well-known result on spherical varieties and a version of Schelter's catenarity theorem for G-primes. 2000 Mathematics Subject Classification. 16R30, 16W22.
Verifying and Synthesizing Constant-Resource Implementations with Types

Side channel attacks have been used to extract critical data such as encryption keys and confidential user data in a variety of adversarial settings. In practice, this threat is addressed by adhering to a constant-time programming discipline, which imposes strict constraints on the way in which programs are written. This introduces an additional hurdle for programmers faced with the already difficult task of writing secure code, highlighting the need for solutions that give the same source-level guarantees while supporting more natural programming models. We propose a novel type system for verifying that programs correctly implement constant-resource behavior. Our type system extends recent work on automatic amortized resource analysis (AARA), a set of techniques that automatically derive provable upper bounds on the resource consumption of programs. We devise new techniques that build on the potential method to achieve compositionality, precision, and automation. A strict global requirement that a program always maintains constant resource usage is too restrictive for most practical applications. It is sufficient to require that the program's resource behavior remain constant with respect to an attacker who is only allowed to observe part of the program's state and behavior. To account for this, our type system incorporates information flow tracking into its resource analysis. This allows our system to certify programs that need to violate the constant-time requirement in certain cases, as long as doing so does not leak confidential information to attackers. We formalize this guarantee by defining a new notion of resource-aware noninterference, and prove that our system enforces it. Finally, we show how our type inference algorithm can be used to synthesize a constant-time implementation from one that cannot be verified as secure, effectively repairing insecure programs automatically. We also show how a second novel AARA system that computes lower bounds on resource usage can be used to derive quantitative bounds on the amount of information that a program leaks through its resource use. We implemented each of these systems in Resource Aware ML, and show that it can be applied to verify constant-time behavior in a number of applicationsincluding encryption and decryption routines, database queries, and other resource-aware functionality.
Typical blocks of Lie superalgebras in prime characteristic

For a type I basic classical Lie superalgebra , we establish an equivalence between typical blocks of categories of U χ(&#x1d524;)-modules and -modules. We then deduce various consequences from the equivalence.
Fields of moduli of three-point G-covers with cyclic p-Sylow, I

We examine in detail the stable reduction of Galois covers of the projective line over a complete discrete valuation field of mixed characteristic (0, p), where G has a cyclic p-Sylow subgroup of order p^n. If G is further assumed to be p-solvable (i.e., G has no nonabelian simple composition factors with order divisible by p), we obtain the following consequence: Suppose f: Y --> P^1 is a three-point G-Galois cover defined over the complex numbers. Then the nth higher ramification groups above p for the upper numbering of the (Galois closure of the) extension K/Q vanish, where K is the field of moduli of f. This extends work of Beckmann and Wewers. Additionally, we completely describe the stable model of a general three-point Z/p^n-cover, where p > 2.