cssi/SciSciGPT-SciSciNet huggingface dataset:
A Two-Component System That Modulates Cyclic di-GMP Metabolism Promotes Legionella pneumophila Differentiation and Viability in Low-Nutrient Conditions

During its life cycle, the environmental pathogen Legionella pneumophila alternates between a replicative and transmissive cell type when cultured in broth, macrophages, or amoebae. Within a protozoan host, L. pneumophila further differentiates into the hardy cell type known as the mature infectious form (MIF). The second messenger cyclic di-GMP coordinates lifestyle changes in many bacterial species, but its role in the L. pneumophila life cycle is less understood. Using an in vitro broth culture model that approximates the intracellular transition from the replicative to the transmissive form, here we investigate the contribution to L. pneumophila differentiation of a two-component system (TCS) that regulates cyclic di-GMP metabolism. The TCS is encoded by lpg0278-lpg0277 and is cotranscribed with lpg0279, which encodes a protein upregulated in MIF cells. The promoter for this operon is RpoS dependent and induced in nutrient-limiting conditions that do not support replication, as demonstrated using a gfp reporter and quantitative PCR (qPCR). The response regulator of the TCS (Lpg0277) is a bifunctional enzyme that both synthesizes and degrades cyclic di-GMP. Using a panel of site-directed point mutants, we show that cyclic di-GMP synthesis mediated by a conserved GGDEF domain promotes growth arrest of replicative L. pneumophila, accumulation of pigment and poly-3-hydroxybutyrate storage granules, and viability in nutrient-limiting conditions. Genetic epistasis tests predict that the MIF protein Lpg0279 acts as a negative regulator of the TCS. Thus, L. pneumophila is equipped with a regulatory network in which cyclic di-GMP stimulates the switch from a replicative to a resilient state equipped to survive in low-nutrient environments.IMPORTANCE Although an intracellular pathogen, L. pneumophila has developed mechanisms to ensure long-term survival in low-nutrient aqueous conditions. Eradication of L. pneumophila from contaminated water supplies has proven challenging, as outbreaks have been traced to previously remediated systems. Understanding the genetic determinants that support L. pneumophila persistence in low-nutrient environments can inform design and assessment of remediation strategies. Here we characterize a genetic locus that encodes a two-component signaling system (lpg0278-lpg0277) and a putative regulator protein (lpg0279) that modulates the production of the messenger molecule cyclic di-GMP. We show that this locus promotes both L. pneumophila cell differentiation and survival in nutrient-limiting conditions, thus advancing the understanding of the mechanisms that contribute to L. pneumophila environmental resilience.
Comparative theoretical investigation of the vertical excitation energies and the electronic structure of [MoVOCl4]-: influence of basis set and geometry.

The electronic structures, geometries, and vibration frequencies of the open-shell molybdenum(V) ion, [MoOCl(4)](-), have been calculated at the extended Huckel, semiempirical ZINDO/1, ZINDO/S, and PM3(tm), as well as ab initio and DFT theoretical levels. Electronic structure calculations suggest that the expected metal-fold orbital order can be satisfied only at the DFT level. The time-dependent density functional theory (TDDFT) approach has been used for the calculation of the vertical excitation energies in the UV-vis region with different basis sets, starting geometries, and exchange-correlation functionals. A good agreement between the predicted and the experimental electronic absorption and MCD spectra of the complex, [MoOCl(4)](-), was observed when the B3LYP and B3P86 exchange-correlation functionals were used with a full electron valence double-zeta with polarization basis set for the molybdenum and 6-311G(d) for all other atoms. Similar results were obtained when the LANL2DZ effective core potential for molybdenum atom and 6-31G(d) for all other atoms were used. The best absolute deviation of 0.13 and mean deviation of 0.01 eV were calculated for the bands in the UV-vis region by B3P86, while the results for the B3LYP exchange-correlation functional were less satisfactory. Compared to polarization functions, the inclusion of diffuse functions resulted in little improvement. The calculated excitations energies and charge-transfer band intensities are found to be sensitive to the Mo=O distance and O-Mo-Cl angle.
Trimethylsilyl trifluoromethanesulfonate (TMSOTf) assisted facile deprotection of N,O-acetonides.

Employing TMSOTf as an easily available reagent, we have developed a mild and efficient method for the deprotection of both terminal and internal N,O-acetonide functionalities. Various regularly used protecting groups and common organic functional moieties were found to be unaffected by the described reaction conditions. In a few representative examples, the present method was also extended to deprotect acetonides obtained from 1,2-, and 1,3-terminal diols. The acetonide deprotection protocol described herein is expected to be a useful addition to the presently available methods for performing the above transformation.
Decarboxylative trifluoromethylation of aryl halides using well-defined copper–trifluoroacetate and –chlorodifluoroacetate precursors

Abstract New synthetic routes to (NHC)copper–trifluoroacetate and –chlorodifluoroacetate complexes were developed (NHC = N-heterocyclic carbenes) so baseline reactivity patterns could be established for the decarboxylative trifluoromethylation of organic halides. In the presence of aryl halides, loss of CO2 from these new precursors occurred at 160 °C concurrent with the formation of aryl–CF3.
Discovery of potent pyrrolidone-based HIV-1 protease inhibitors with enhanced drug-like properties.

Abstract We have developed efficient syntheses of the HIV-1 protease inhibitor 4 and its analogues, which incorporate the pyrrolidone scaffold 2 as P1–P2 moiety. Evaluation of these analogues in the HIV-1 protease enzyme assay resulted in discovery of potent and more water soluble meta-amino- and meta-hydroxy inhibitors 17b and 19b. The SAR observed in this class of PIs could be rationalized with aid of the X-ray structure of inhibitor 28 co-crystallized with the HIV-1 protease, which suggested that the polar meta- (but not para-) benzyl substituents in P2 could side-step the hydrophobic S2 enzyme active pocket by rotating the P2 moiety around its Cβ–Cγ bond. Such reorientation allows to engage the unsubstituted, hydrophobic edge of benzyl moiety in P2 in the requisite P2/S2 hydrophobic interaction, and projects polar meta-substituent into the bound water. It appears that the meta-position can be chemically derivatized without potency loss of thus resulting inhibitors, as evidenced by potent 22–26. We thus identified pyrrolidone 2-based inhibitors exemplified by 17b and 19b, which uniquely accommodate both high enzyme potency and which provide a platform for fine-tuning of drug-like properties in this class of PIs by additional chemical manipulations on the meta-position.
The synthesis of Z-allylic alcohols via palladium-mediated reactions of stannoxanes with aryl halides

Abstract The palladium-mediated reactions of stannoxanes with aryl halides affords Z-allylic alcohols in good to excellent yields. In many cases, the use of nitrobenzene as solvent dramatically improved the yields.
Matrix isolation and theoretical study of the photochemical reaction of PH3 with OVCl3 and CrCl2O2

The matrix isolation technique has been combined with theoretical calculations to identify and characterize the photoproducts in the reaction of PH3 with OVCl3 and CrCl2O2. In contrast to previous studies, HCl elimination from an initial complex is not observed. Instead, a number of product bands, some quite intense, were observed and have been assigned to phosphine oxide, H3PO, through the direct O atom transfer from the transition metal oxo compound. This identification was supported by extensive isotopic labeling, and by comparison to theoretical calculations. H3PO formed in this manner is cage-paired and interacts with the transition metal fragment (VCl3 or Cl2CrO), leading to a 113 cm-1 red-shift of the PO stretching mode relative to isolated monomeric H3PO.
New conjunctive reagents as cross-coupling partners en route to retinoid-like polyenes.

New conjunctive reagents E-2 and Z-3 can be used, after transmetalation, in Negishi couplings with vinyl and aryl iodides. The subsequently unmasked terminal alkynes can be further manipulated to arrive at retinoid-like products.
A phenome-wide examination of neural and cognitive function

This data descriptor outlines a shared neuroimaging dataset from the UCLA Consortium for Neuropsychiatric Phenomics, which focused on understanding the dimensional structure of memory and cognitive control (response inhibition) functions in both healthy individuals (130 subjects) and individuals with neuropsychiatric disorders including schizophrenia (50 subjects), bipolar disorder (49 subjects), and attention deficit/hyperactivity disorder (43 subjects). The dataset includes an extensive set of task-based fMRI assessments, resting fMRI, structural MRI, and high angular resolution diffusion MRI. The dataset is shared through the OpenfMRI project, and is formatted according to the Brain Imaging Data Structure (BIDS) standard.
Preparation and Tungsten-183 NMR Characterization of [α-1-P2W17O61]10-, [α-1-Zn(H2O)P2W17O61]8-, and [α-2-Zn(H2O)P2W17O61]8-

The preparation of the α-1 and α-2 isomers of the Wells−Dawson 17 tungsto derivatives by standard methods is accompanied by a significant proportion of the other isomer present as an impurity. In this study, the α-1 and α-2 isomers of [Zn(H2O)P2W17O61]8- have been prepared in >98% purity by reacting isomerically pure K9Li[α-1-P2W17O61] and K10[α-2-P2W17O61], respectively, with ZnCl2, while rigorously controlling the pH at 4.7. The molecules were isolated as potassium salts. For 183W NMR and 31P NMR characterization, both molecules were ion exchanged by cation-exchange chromatography, maintaining the pH at 4.7, to obtain the lithium salts. Removal of water and isolation of a solid sample of [α-1-Zn(H2O)P2W17O61]8- was achieved by lyophilization at −40 °C. The chemical shift data from 31P and 183W NMR spectroscopy of the isolated [α-1-Zn(H2O)P2W17O61]8- and [α-2-Zn(H2O)P2W17O61]8- isomers are consistent with a mixture of the α-1 and α-2 isomers reported previously;1 the molecules have the expected C1 and Cs...
Polytypism in the Nb3TeI7 system

Abstract h-Nb3TeI7 represents the first polytype to be observed in a single ternary system of the layered Nb3QX7 family (Q=S, Se, Te; X=Cl, Br, I). This compound was synthesized by stoichiometric reaction of the elements at temperatures from 600° to 800°C, and was characterized by single crystal and powder X-ray diffraction. h-Nb3TeI7 crystallizes in the Nb3SBr7 structure type: space group P3m1, a=7.642(1) A, c=6.897(1) A and V=348.82(8) A3. h-Nb3TeI7 differs from the previously reported polytype, hc-Nb3TeI7, by having a simpler anion layer stacking sequence involving fewer 2 ∞ [ Nb 3 TeI 7 ] layers per unit cell. Complete structural determinations of the new compound h-Nb3TeI7 as well as of the previously reported hc-Nb3TeI7 are included.
Dioxa-[40]decaphyrin(1.0.1.0.0.1.0.1.0.0): An analogue of turcasarin with a figure-eight structure

The synthesis and characterization of two different furan containing analogues of turcasarin, namely 46,51 -dioxa-2,11,15,20,24,33,37,42-octapropyl-turcasarin (7a) and 46,51 -dioxa-2,11,24,33-tetrapropyl-15,20,37,42-tetraethyl-16,19,38,41-tetramethyl-turcasarin (7b) are described. While 7a was found to exhibit a “figure eight” structure in solution and in the solid state, 7b is believed to adopt a different, more symmetric conformation is solution.
Methyl 4-O-β-L-galactopyranosyl-β-D-glucopyranoside (methyl β-L-lactoside)

Methyl beta-L-lactoside, C13H24O11, (II), is described by glycosidic torsion angles phi (O5Gal-C1Gal-O4Glc-C4Glc) and psi (C1Gal-O1Gal-C4Glc-C5Glc) of 93.89 (13) and -127.43 (13) degrees , respectively, where the ring atom numbering conforms to the convention in which C1 is the anomeric C atom and C6 is the exocyclic hydroxymethyl (CH2OH) C atom in both residues (Gal is galactose and Glc is glucose). Substitution of L-Gal for D-Gal in the biologically relevant disaccharide, methyl beta-lactoside [Stenutz, Shang & Serianni (1999). Acta Cryst. C55, 1719-1721], (I), significantly alters the glycosidic linkage interface. In the crystal structure of (I), one inter-residue (intramolecular) hydrogen bond is observed between atoms H3OGlc and O5Gal. In contrast, in the crystal structure of (II), inter-residue hydrogen bonds are observed between atoms H6OGlc and O5Gal, H6OGlc and O6Gal, and H3OGlc and O2Gal, with H6OGlc serving as a donor with two intramolecular acceptors.
Deletion of the creatine transporter gene in neonatal, but not adult, mice leads to cognitive deficits.

Creatine (Cr) is a guanidino compound that provides readily available phosphate pools for the regeneration of spent adenosine triphosphate (ATP). The lack of brain Cr causes moderate to severe intellectual disability, language impairment, and epilepsy. The most prevalent cause of Cr deficiency are mutations in the X-linked SLC6A8 (Creatine transporter; CrT) gene, known as CrT deficiency (CTD). One of the most critical areas that need to be addressed is whether Cr is necessary for brain development. To address this concern, the Slc6a8 gene was knocked out in either neonatal (postnatal day (P)5) or adult (P60) mice using a tamoxifen-inducible Cre recombinase driven by the human ubiquitin C (UBC) promoter. Mice were tested in the Morris water maze, novel, object recognition, and conditioned fear 60 days after Slc6a8 deletion. In addition, overnight locomotor activity was analyzed. Mice that had the gene deleted on P5 showed deficits in the Morris water maze and novel object recognition, while there were no deficits in P60 knockout mice. Interestingly, the P5 knockout mice showed hyperactivity during the dark phase; however, when examining control mice, the effect was due to the administration of tamoxifen from P5 to 10. Taken together, the results of this study show that Cr is necessary during periods of brain development involved in spatial and object learning. This study also highlights the continued importance of using proper control groups for behavioral testing.
Substituent Effects in the Intramolecular Diels−Alder Reaction of 6-Furylhexenoates

The series of furyl enone esters, 4a−c, were synthesized from furan or furfural by straightforward routes. Their thermal intramolecular Diels−Alder reactions to give the tricyclic ketones 5a−c were...
Highest weight sl_2-categorifications II: structure theory

This paper continues the study of highest weight categorical sl2-actions initi- ated in part I. We start by refining the definition given there and showing that all examples considered in part I are also highest weight categorifications in the refined sense. Then we prove that any highest weight sl2-categorification can be filtered in such a way that the suc- cessive quotients are so called basic highest weight sl2-categorifications. For a basic highest weight categorification we determine minimal projective resolutions of standard objects. We use this, in particular, to examine the structure of tilting objects in basic categorifications and to show that the Ringel duality is given by the Rickard complex. We apply some of these structural results to categories O for cyclotomic Rational Cherednik algebras. We finish by discussing open problems.
Efficient Sampling for k-Determinantal Point Processes

Determinantal Point Processes (DPPs) are elegant probabilistic models of repulsion and diversity over discrete sets of items. But their applicability to large sets is hindered by expensive cubic-complexity matrix operations for basic tasks such as sampling. In light of this, we propose a new method for approximate sampling from discrete k-DPPs. Our method takes advantage of the diversity property of subsets sampled from a DPP, and proceeds in two stages: first it constructs coresets for the ground set of items; thereafter, it efficiently samples subsets based on the constructed coresets. As opposed to previous approaches, our algorithm aims to minimize the total variation distance to the original distribution. Experiments on both synthetic and real datasets indicate that our sampling algorithm works efficiently on large data sets, and yields more accurate samples than previous approaches.
Polite Dialogue Generation Without Parallel Data

Stylistic dialogue response generation, with valuable applications in personality-based conversational agents, is a challenging task because the response needs to be fluent, contextually-relevant, ...
Asymptotic joint distribution of the extremities of a random Young diagram and enumeration of graphical partitions

Abstract An integer partition of n is a decreasing sequence of positive integers that add up to [ n ] . Back in 1979 Macdonald posed a question about the limit value of the probability that two partitions chosen uniformly at random, and independently of each other, are comparable in terms of the dominance order. In 1982 Wilf conjectured that the uniformly random partition is a size-ordered degree sequence of a simple graph with the limit probability 0. In 1997 we showed that in both, seemingly unrelated, cases the limit probabilities are indeed zero, but our method left open the problem of convergence rates. The main result in this paper is that each of the probabilities is e − 0.11 log ⁡ n / log ⁡ log ⁡ n , at most. A key element of the argument is a local limit theorem, with convergence rate, for the joint distribution of the [ n 1 / 4 − e ] tallest columns and the [ n 1 / 4 − e ] longest rows of the Young diagram representing the random partition.
Efficient Interference Management Policies for Femtocell Networks

Managing interference in a network of macrocells underlaid with femtocells presents an important, yet challenging problem. A majority of spatial (frequency/time) reuse based approaches partition the users based on coloring the interference graph, which is shown to be suboptimal. Some spatial time reuse based approaches schedule the maximal independent sets (MISs) in a cyclic, (weighted) round-robin fashion, which is inefficient for delay-sensitive applications. Our proposed policies schedule the MISs in a non-cyclic fashion, which aim to optimize any given network performance criterion for delay-sensitive applications while fulfilling minimum throughput requirements of the users. Importantly, we do not take the interference graph as given as in existing works; we propose an optimal construction of the interference graph. We prove that under certain conditions, the proposed policy achieves the optimal network performance. For large networks, we propose a low-complexity algorithm for computing the proposed policy. We show that the policy computed achieves a constant competitive ratio (with respect to the optimal network performance), which is independent of the network size, under wide range of deployment scenarios. The policy can be implemented in a decentralized manner by the users. Compared to the existing policies, our proposed policies can achieve improvement of up to 130% in large-scale deployments.
Functorial reconstruction theorems for stacks

Abstract We study the circumstances under which one can reconstruct a stack from its associated functor of isomorphism classes. This is possible surprisingly often: we show that many of the standard examples of moduli stacks are determined by their functors. Our methods seem to exhibit new anabelian-style phenomena, in the form of structures in the category of schemes that encode automorphism data in groupoids.
Dynamical Systems and Sheaves

A categorical framework for modeling and analyzing systems in a broad sense is proposed. These systems should be thought of as ‘machines’ with inputs and outputs, carrying some sort of signal that occurs through some notion of time. Special cases include continuous and discrete dynamical systems (e.g. Moore machines). Additionally, morphisms between the different types of systems allow their translation in a common framework. A central goal is to understand the systems that result from arbitrary interconnection of component subsystems, possibly of different types, as well as establish conditions that ensure totality and determinism compositionally. The fundamental categorical tools used here include lax monoidal functors, which provide a language of compositionality, as well as sheaf theory, which flexibly captures the crucial notion of time.
Soft Actor-Critic: Off-Policy Maximum Entropy Deep Reinforcement Learning with a Stochastic Actor

Model-free deep reinforcement learning (RL) algorithms have been demonstrated on a range of challenging decision making and control tasks. However, these methods typically suffer from two major challenges: very high sample complexity and brittle convergence properties, which necessitate meticulous hyperparameter tuning. Both of these challenges severely limit the applicability of such methods to complex, real-world domains. In this paper, we propose soft actor-critic, an off-policy actor-critic deep RL algorithm based on the maximum entropy reinforcement learning framework. In this framework, the actor aims to maximize expected reward while also maximizing entropy. That is, to succeed at the task while acting as randomly as possible. Prior deep RL methods based on this framework have been formulated as Q-learning methods. By combining off-policy updates with a stable stochastic actor-critic formulation, our method achieves state-of-the-art performance on a range of continuous control benchmark tasks, outperforming prior on-policy and off-policy methods. Furthermore, we demonstrate that, in contrast to other off-policy algorithms, our approach is very stable, achieving very similar performance across different random seeds.
Comparing dataset characteristics that favor the Apriori, Eclat or FP-Growth frequent itemset mining algorithms

Frequent itemset mining is a popular data mining technique. Apriori, Eclat, and FP-Growth are among the most common algorithms for frequent itemset mining. Considerable research has been performed to compare the relative performance between these three algorithms, by evaluating the scalability of each algorithm as the dataset size increases. While scalability as data size increases is important, previous papers have not examined the performance impact of similarly sized datasets that contain different itemset characteristics. This paper explores the effects that two dataset characteristics can have on the performance of these three frequent itemset algorithms. To perform this empirical analysis, a dataset generator is created to measure the effects of frequent item density and the maximum transaction size on performance. The generated datasets contain the same number of rows. This provides some insight into dataset characteristics that are conducive to each algorithm. The results of this paper's research demonstrate Eclat and FP-Growth both handle increases in maximum transaction size and frequent itemset density considerably better than the Apriori algorithm.
The Shuffle Algebra Revisited

In this paper we introduce certain new features of the shuffle algebra of [3] that will allow us to obtain explicit formulas for the isomorphism between its Drinfeld double and the elliptic Hall algebra of [1], [7]. These results are necessary for our work in [4] and [6], where they will be applied to the study of the Hilbert scheme and to computing knot invariants.
A general class of spreading processes with non-Markovian dynamics

In this paper we propose a general class of models for spreading processes we call the SI*V * model. Unlike many works that consider a fixed number of compartmental states, we allow an arbitrary number of states on arbitrary graphs with heterogeneous parameters for all nodes and edges. As a result, this generalizes an extremely large number of models studied in the literature including the MSEIV, MSEIR, MSEIS, SEIV, SEIR, SEIS, SIV, SIRS, SIR, and SIS models. Furthermore, we show how the SI*V * model allows us to model non-Poisson spreading processes letting us capture much more complicated dynamics than existing works such as information spreading through social networks or the delayed incubation period of a disease like Ebola. This is in contrast to the overwhelming majority of works in the literature that only consider dynamics that can be captured by Markov processes. After developing the stochastic model, we analyze its deterministic mean-field approximation and provide conditions for when the disease-free equilibrium is stable. Simulations illustrate our results.
On transfer operators on the circle with trigonometric weights

We study spectral properties of the transfer operators $L$ defined on the circle $\mathbb T=\mathbb R/\mathbb Z$ by $$(Lu)(t)=\frac{1}{d}\sum_{i=0}^{d-1} f\left(\frac{t+i}{d}\right)u\left(\frac{t+i}{d}\right),\ t\in\mathbb T$$ where $u$ is a function on $\mathbb T$. We focus in particular on the cases $f(t)=|\cos(\pi t)|^q$ and $f(t)=|\sin(\pi t)|^q$, which are closely related to some classical Fourier-analytic questions. We also obtain some explicit computations, particularly in the case $d=2$. Our study extends work of Strichartz \cite{Strichartz1990} and Fan and Lau \cite{FanLau1998}.
Mathematics of Topological Quantum Computing

In topological quantum computing, information is encoded in “knotted” quantum states of topological phases of matter, thus being locked into topology to prevent decay. Topological precision has been confirmed in quantum Hall liquids by experiments to an accuracy of 10^-10, and harnessed to stabilize quantum memory. In this survey, we discuss the conceptual development of this interdisciplinary field at the juncture of mathematics, physics and computer science. Our focus is on computing and physical motivations, basic mathematical notions and results, open problems and future directions related to and/or inspired by topological quantum computing.
Efficiency enhancement of ultrathin CIGS solar cells by optimal bandgap grading

Typographical errors in a few equations in [Appl. Opt.58, 6067 (2019)APOPAI0003-693510.1364/AO.58.006067] are corrected.
Hermitian-holomorphic Deligne cohomology, Deligne pairing for singular metrics, and hyperbolic metrics

We introduce a model for Hermitian holormorphic Deligne cohomology on a projective algebraic manifold which allows to incorporate singular hermitian structures along a normal crossing divisor. In the case of a projective curve, the cup-product in cohomology is shown to correspond to a generalization of the Deligne pairing to line bundles with “good” hermitian metrics in the sense of Mumford and others. A particular case is that of the tangent bundle of the curve twisted by the negative of the singularity divisor of a hyperbolic metric: its cup square (corrected by the total area) is shown to be a functional whose extrema are the metrics of constant negative curvature.
Traces of singular values of Hauptmoduln

In an important paper, Zagier proved that certain half-integral weight modular forms are generating functions for traces of polynomials in the j-function. It turns out that Zagier's work makes it possible to algorithmically compute Hilbert class polynomials using a canonical family of modular forms of weight . We generalize these results and consider Hauptmoduln for levels 1, 2, 3, 5, 7, and 13. We show that traces of singular values of polynomials in Hauptmoduln are again described by coefficients of half-integral weight modular forms. This realization makes it possible to algorithmically compute class polynomials.
Generalized test ideals, sharp F-purity, and sharp test elements

Consider a pair $(R, \ba^t)$ where $R$ is a ring of positive characteristic, $\ba$ is an ideal such that $\ba \cap R^{\circ} \neq \emptyset$, and $t > 0$ is a real number. In this situation we have the ideal $\tau_R(\ba^t)$, the generalized test ideal associated to $(R, \ba^t)$ as defined by Hara and Yoshida. We show that $\tau_R(\ba^t) \cap R^{\circ}$ is made up of appropriately defined generalized test elements which we call \emph{\ste s}. We also define a variant of $F$-purity for pairs, \emph{\sfpty}, which interacts well with \ste s and agrees with previously defined notions of $F$-purity in many common situations. We show that if $(R, \ba^t)$ is \sfp, then $\tau_R(\ba^t)$ is a radical ideal. Furthermore, by following an argument of Vassilev, we show that if $R$ is a quotient of an $F$-finite regular local ring and $(R, \ba^t)$ is \sfp, then $R/\tau_R(\ba^t)$ itself is $F$-pure. We conclude by showing that \sfpty{ }can be used to define the $F$-pure threshold. As an application we show that the $F$-pure threshold must be a rational number under certain hypotheses.
An unsupervised and customizable misspelling generator for mining noisy health-related text sources

Background Data collection and extraction from noisy text sources such as social media typically rely on keyword-based searching/listening. However, health-related terms are often misspelled in such noisy text sources due to their complex morphology, resulting in the exclusion of relevant data for studies. In this paper, we present a customizable data-centric system that automatically generates common misspellings for complex health-related terms, which can improve the data collection process from noisy text sources. Materials and methods The spelling variant generator relies on a dense vector model learned from large, unlabeled text, which is used to find semantically close terms to the original/seed keyword, followed by the filtering of terms that are lexically dissimilar beyond a given threshold. The process is executed recursively, converging when no new terms similar (lexically and semantically) to the seed keyword are found. The weighting of intra-word character sequence similarities allows further problem-specific customization of the system. Results On a dataset prepared for this study, our system outperforms the current state-of-the-art medication name variant generator with best F 1 - score of 0.69 and F 1 4 - score of 0.78. Extrinsic evaluation of the system on a set of cancer-related terms demonstrated an increase of over 67% in retrieval rate from Twitter posts when the generated variants are included. Discussion Our proposed spelling variant generator has several advantages over past spelling variant generators—(i) it is capable of filtering out lexically similar but semantically dissimilar terms, (ii) the number of variants generated is low, as many low-frequency and ambiguous misspellings are filtered out, and (iii) the system is fully automatic, customizable and easily executable. While the base system is fully unsupervised, we show how supervision may be employed to adjust weights for task-specific customizations. Conclusion The performance and relative simplicity of our proposed approach make it a much-needed spelling variant generation resource for health-related text mining from noisy sources. The source code for the system has been made publicly available for research.
Pruning and Nonparametric Multiple Change Point Detection

Change point analysis is a statistical tool to identify homogeneity within time series data. We propose a pruning approach for approximate nonparametric estimation of multiple change points. This general purpose change point detection procedure 'cp3o' applies a pruning routine within a dynamic program to greatly reduce the search space and computational costs. Existing goodness-of-fit change point objectives can immediately be utilized within the framework. We further propose novel change point algorithms by applying cp3o to two popular nonparametric goodness of fit measures: 'e-cp3o' uses E-statistics, and 'ks-cp3o' uses Kolmogorov-Smirnov statistics. Simulation studies highlight the performance of these algorithms in comparison with parametric and other nonparametric change point methods. Finally, we illustrate these approaches with climatological and financial applications.
Coxeter–Chein Loops

In 1974, Orin Chein discovered a new family of Moufang loops which are now called Chein loops. Such a loop can be created from any group W together with ℤ2 by a variation on a semidirect product. We first settle an open problem, originally proposed by Petr Vojtěchovský in 2003, by finding a minimal presentation for the Chein loop with respect to a presentation for W. We then study these loops in the case where W is a Coxeter group and show that it has what we call a Chein-Coxeter system, a small set of generators of order 2, together with a set of relations closely related to the Coxeter relations and Chein relations. In particular, even if the Moufang loop is infinite, it is finitely presented. Viewing these presentations as amalgams of loops, we then apply methods due to Blok and Hoffman to describe a family of twisted Coxeter–Chein loops.
Asking the Right Question: Inferring Advice-Seeking Intentions from Personal Narratives.

People often share personal narratives in order to seek advice from others. To properly infer the narrator’s intention, one needs to apply a certain degree of common sense and social intuition. To test the capabilities of NLP systems to recover such intuition, we introduce the new task of inferring what is the advice-seeking goal behind a personal narrative. We formulate this as a cloze test, where the goal is to identify which of two advice-seeking questions was removed from a given narrative. The main challenge in constructing this task is finding pairs of semantically plausible advice-seeking questions for given narratives. To address this challenge, we devise a method that exploits commonalities in experiences people share online to automatically extract pairs of questions that are appropriate candidates for the cloze task. This results in a dataset of over 20,000 personal narratives, each matched with a pair of related advice-seeking questions: one actually intended by the narrator, and the other one not. The dataset covers a very broad array of human experiences, from dating, to career options, to stolen iPads. We use human annotation to determine the degree to which the task relies on common sense and social intuition in addition to a semantic understanding of the narrative. By introducing several baselines for this new task we demonstrate its feasibility and identify avenues for better modeling the intention of the narrator.
What Stops Social Epidemics

Theoretical progress in understanding the dynamics of spreading processes on graphs suggests the existence of an epidemic threshold below which no epidemics form and above which epidemics spread to a significant fraction of the graph. We have observed information cascades on the social media site Digg that spread fast enough for one initial spreader to infect hundreds of people, yet end up affecting only 0.1% of the entire network. We find that two effects, previously studied in isolation, combine cooperatively to drastically limit the final size of cascades on Digg. First, because of the highly clustered structure of the Digg network, most people who are aware of a story have been exposed to it via multiple friends. This structure lowers the epidemic threshold while moderately slowing the overall growth of cascades. In addition, we find that the mechanism for social contagion on Digg points to a fundamental difference between information spread and other contagion processes: despite multiple opportunities for infection within a social group, people are less likely to become spreaders of information with repeated exposure. The consequences of this mechanism become more pronounced for more clustered graphs. Ultimately, this effect severely curtails the size of social epidemics on Digg.
Sparsely Connected and Disjointly Trained Deep Neural Networks for Low Resource Behavioral Annotation: Acoustic Classification in Couples' Therapy.

Observational studies are based on accurate assessment of human state. A behavior recognition system that models interlocutors' state in real-time can significantly aid the mental health domain. However, behavior recognition from speech remains a challenging task since it is difficult to find generalizable and representative features because of noisy and high-dimensional data, especially when data is limited and annotated coarsely and subjectively. Deep Neural Networks (DNN) have shown promise in a wide range of machine learning tasks, but for Behavioral Signal Processing (BSP) tasks their application has been constrained due to limited quantity of data. We propose a Sparsely-Connected and Disjointly-Trained DNN (SD-DNN) framework to deal with limited data. First, we break the acoustic feature set into subsets and train multiple distinct classifiers. Then, the hidden layers of these classifiers become parts of a deeper network that integrates all feature streams. The overall system allows for full connectivity while limiting the number of parameters trained at any time and allows convergence possible with even limited data. We present results on multiple behavior codes in the couples' therapy domain and demonstrate the benefits in behavior classification accuracy. We also show the viability of this system towards live behavior annotations.
Characterization of Calabi–Yau variations of Hodge structure over tube domains by characteristic forms

Sheng and Zuo’s characteristic forms are invariants of a variation of Hodge structure. We show that they characterize Gross’s canonical variations of Hodge structure of Calabi–Yau type over (Hermitian symmetric) tube domains.
A prototype of wireless power and data acquisition system for large detectors

Abstract We have developed a prototype detector and data acquisition module that incorporates wireless power and wireless data transmission techniques. The module has no electrical connections. It receives power using photovoltaic devices, and communicates control, timing, trigger, and data using the 802.11n wireless communication standard. The work is part of a study for building a large detector having many readout channels, where it is desirable to reduce the cable plant and infrastructure. The system could also be deployed in smaller detectors that require mobility or are difficult to cable due to extreme conditions. We describe the design and operation of the prototype module, including benchmark performance measurements, and discuss aspect and issues in extrapolating to a large detector system.
Group actions and covering maps in the uniform category

Abstract In Rips complexes and covers in the uniform category (Brodskiy et al. [4] ) we define, following James (1990) [9] , covering maps of uniform spaces and introduce, inspired by Berestovskii and Plaut (2007) [2] , the concept of generalized uniform covering maps. In this paper we investigate when these covering maps are induced by group actions which allows us to relate our covering maps to those in Berestovskii and Plaut (2007) [2] . Also, as an application of our results we present an exposition of Prajs' (2002) [16] homogeneous curve that is path-connected but not locally connected.
Sharp Bounds for Generalized Uniformity Testing

We study the problem of generalized uniformity testing of a discrete probability distribution: Given samples from a probability distribution p over an unknown size discrete domain Ω, we want to distinguish, with probability at least 2/3, between the case that p is uniform on some subset of Ω versus e-far, in total variation distance, from any such uniform distribution. We establish tight bounds on the sample complexity of generalized uniformity testing. In more detail, we present a computationally efficient tester whose sample complexity is optimal, within constant factors, and a matching worst-case information-theoretic lower bound. Specifically, we show that the sample complexity of generalized uniformity testing is Θ(1/(e^(4/3) ||p||_3) + 1/(e^2 ||p||_2 )).
A unified power control algorithm for multiuser detectors in large systems: Convergence and performance

A unified approach to energy-efficient power control, applicable to a large family of receivers including the matched filter, the decorrelator, the (linear) minimum-mean-square-error detector (MMSE), and the individually and jointly optimal multiuser detectors, has recently been proposed for code-division-multiple-access (CDMA) networks. This unified power control (UPC) algorithm exploits the linear relationship that has been shown to exist between the transmit power and the output signal-to-interference-plus-noise ratio (SIR) in large systems. Based on this principle and by computing the multiuser efficiency, the UPC algorithm updates the users' transmit powers in an iterative way to achieve the desired target SIR. In this paper, the convergence of the UPC algorithm is proved for the matched filter, the decorrelator, and the MMSE detector. In addition, the performance of the algorithm in finite-size systems is studied and compared with that of existing power control schemes. The UPC algorithm is particularly suitable for systems with randomly generated long spreading sequences (i.e., sequences whose period is longer than one symbol duration).
Almost purity and overconvergent Witt vectors

Abstract In a previous paper, we stated a general almost purity theorem in the style of Faltings: if R is a ring for which the Frobenius maps on finite p -typical Witt vectors over R are surjective, then the integral closure of R in a finite etale extension of R [ p − 1 ] is “almost” finite etale over R . Here, we use almost purity to lift the finite etale extension of R [ p − 1 ] to a finite etale extension of rings of overconvergent Witt vectors . The point is that no hypothesis of p -adic completeness is needed; this result thus points towards potential global analogues of p -adic Hodge theory. As an illustration, we construct ( φ , Γ ) -modules associated with Artin Motives over Q . The ( φ , Γ ) -modules we construct are defined over a base ring which seems well-suited to generalization to a more global setting; we plan to pursue such generalizations in later work.
Uniqueness of self-similar shrinkers with asymptotically conical ends

In this paper, we show the uniqueness of smooth embedded selfshrinkers asymptotic to generalized cylinders of infinite order. Also, we construct non-rotationally symmetric self-shrinking ends asymptotic to generalized cylinders with rate as fast as any given polynomial.
On the Information in Spike Timing: Neural Codes Derived from Polychronous Groups

There is growing evidence regarding the importance of spike timing in neural information processing, with even a small number of spikes carrying information, but computational models lag significantly behind those for rate coding. Experimental evidence on neuronal behavior is consistent with the dynamical and state dependent behavior provided by recurrent connections. This motivates the minimalistic abstraction investigated in this paper, aimed at providing insight into information encoding in spike timing via recurrent connections. We employ information-theoretic techniques for a simple reservoir model which encodes input spatiotemporal patterns into a sparse neural code, translating the polychronous groups introduced by Izhike-vich into codewords on which we can perform standard vector operations. We show that the distance properties of the code are similar to those for (optimal) random codes. In particular, the code meets benchmarks associated with both linear classification and capacity, with the latter scaling exponentially with reservoir size.
A Standard Zero Free Region for Rankin–Selberg L-Functions

A standard zero free region is obtained for Rankin Selberg L-functions $L(s, f\times \widetilde{f})$ where $f$ is an almost everywhere tempered Maass form on $GL(n)$ and $f$ is not necessarily self dual. The method is based on the theory of Eisenstein series generalizing a work of Sarnak.
The Dynamics of Influence Systems

Influence systems form a large class of multiagent systems designed to model how influence, broadly defined, spreads across a dynamic network. We build a general analytical framework which we then use to prove that, while Turing-complete, influence dynamics of the diffusive type is almost surely asymptotically periodic. Besides resolving the dynamics of a popular family of multiagent systems, the other contribution of this work is to introduce a new type of renormalization-based bifurcation analysis for multiagent systems.
Minimal model of Ginzburg algebras

Abstract We compute the minimal model for Ginzburg algebras associated to acyclic quivers Q. In particular, we prove that there is a natural grading on the Ginzburg algebra making it formal and quasi-isomorphic to the preprojective algebra in non-Dynkin type, and in Dynkin type is quasi-isomorphic to a twisted polynomial algebra over the preprojective with a unique higher A ∞ -composition. To prove these results, we construct and study the minimal model of an A ∞ -envelope of the derived category D b ( Q ) whose higher compositions encode the triangulated structure of D b ( Q ) .
The density compression ratio of shock fronts associated with coronal mass ejections

We present a new method to extract the three-dimensional electron density profile and density compression ratio of shock fronts associated with coronal mass ejections (CMEs) observed in white light coronagraph images. We demonstrate the method with two examples of fast halo CMEs (∼2000 km s −1 ) observed on 2011 March 7 and 2014 February 25. Our method uses the ellipsoid model to derive the three-dimensional geometry and kinematics of the fronts. The density profiles of the sheaths are modeled with double-Gaussian functions with four free parameters, and the electrons are distributed within thin shells behind the front. The modeled densities are integrated along the lines of sight to be compared with the observed brightness in COR2-A, and a χ 2 approach is used to obtain the optimal parameters for the Gaussian profiles. The upstream densities are obtained from both the inversion of the brightness in a pre-event image and an empirical model. Then the density ratio and Alfvenic Mach number are derived. We find that the density compression peaks around the CME nose, and decreases at larger position angles. The behavior is consistent with a driven shock at the nose and a freely propagating shock wave at the CME flanks. Interestingly, we find that the supercritical region extends over a large area of the shock and lasts longer (several tens of minutes) than past reports. It follows that CME shocks are capable of accelerating energetic particles in the corona over extended spatial and temporal scales and are likely responsible for the wide longitudinal distribution of these particles in the inner heliosphere. Our results also demonstrate the power of multi-viewpoint coronagraphic observations and forward modeling in remotely deriving key shock properties in an otherwise inaccessible regime.
A quantitative formulation of the global regularity problem for the periodic Navier-Stokes equation

The global regularity problem for the periodic Navier-Stokes system asks whether to every smooth divergence-free initial datum $u_0: (\R/\Z)^3 \to \R^3$ there exists a global smooth solution u. In this note we observe (using a simple compactness argument) that this qualitative question is equivalent to the more quantitative assertion that there exists a non-decreasing function $F: \R^+ \to \R^+$ for which one has a local-in-time \emph{a priori} bound $$ \| u(T) \|_{H^1_x((\R/\Z)^3)} \leq F(\|u_0\|_{H^1_x((\R/\Z)^3)})$$ for all $0 < T \leq 1$ and all smooth solutions $u: [0,T] \times (\R/\Z)^3 \to \R^3$ to the Navier-Stokes system. We also show that this local-in-time bound is equivalent to the corresponding global-in-time bound.