cssi/SciSciGPT-SciSciNet huggingface dataset:
Collective strategy for obstacle navigation during cooperative transport by ants

Group cohesion and consensus have primarily been studied in the context of discrete decisions, but some group tasks require making serial decisions that build on one another. We examine such collective problem solving by studying obstacle navigation during cooperative transport in ants. In cooperative transport, ants work together to move a large object back to their nest. We blocked cooperative transport groups of Paratrechina longicornis with obstacles of varying complexity, analyzing groups' trajectories to infer what kind of strategy the ants employed. Simple strategies require little information, but more challenging, robust strategies succeed with a wider range of obstacles. We found that transport groups use a stochastic strategy that leads to efficient navigation around simple obstacles, and still succeeds at difficult obstacles. While groups navigating obstacles preferentially move directly toward the nest, they change their behavior over time; the longer the ants are obstructed, the more likely they are to move away from the nest. This increases the chance of finding a path around the obstacle. Groups rapidly changed directions and rarely stalled during navigation, indicating that these ants maintain consensus even when the nest direction is blocked. Although some decisions were aided by the arrival of new ants, at many key points, direction changes were initiated within the group, with no apparent external cause. This ant species is highly effective at navigating complex environments, and implements a flexible strategy that works for both simple and more complex obstacles.
Thermolysis of organic compounds under H2 (D2)

Abstract This paper is a review of our experiments and those of other authors which relate to chemical processes taking place when organic compounds are heated under hydrogen or deuterium gas. For the most part, coverage is confined to reactions believed to directly involve H2, D2 or H and D atoms generated therefrom. However, discussion of some follow-up reactions is required to explain the observed distribution of deuterium in products from reactions under D2. Reactions wherein hydrogen is activated by added inorganic catalysts are avoided except as relevant for understanding uncatalyzed examples. Reactions with surface-immoblilized substrates are discussed and related to reactions of coal with hydrogen gas (‘hydroliquefaction’).
Chalcogenopyranones from disodium chalcogenide additions to 1,4-pentadiyn-3-ones. The role of enol ethers as intermediates

Enol ethers 9 are formed as a mixture of E- and Z-isomers from the addition of ethanol to 1,4-pentadiyn-3-ones 2 in sodium ethoxide/ethanol. The enol ethers react with disodium chalcogenides to give the corresponding 2,6-disubstituted chalcogenopyranones 1 bearing alkyl, aryl, or heteroaryl substituents in high yield as the only heterocyclic product of reaction. Diynones 2 react with disodium chalcogenides to give mixtures of products in which the chalcogenopyranones 1 are minor components and the dihydrochalcogenophenes 3 are the major products. The addition of hydrogen sulfide to diynone 2b in ethanol gives a product mixture nearly identical to that observed for the addition of disodium sulfide in sodium ethoxide in ethanol to 2b. Intermediates for the addition of hydrogen chalcogenides and disodium chalcogenides to both 2 and 9 are described, which lead to the heterocyclic products.
The use of alkoxides and related π-donors in organotransition metal chemistry as illustrated by M2(OR)6 compounds (M = Mo or W)

Abstract The versatile role of alkoxide ligands in the development of organotransition metal chemistry is illustrated in the chemistry of M 2 (OR) 6 compounds (M = Mo or W) with particular emphasis on the activation of carbon monoxide, alkynes, ethene and allene. The specific selection of R allows for the tuning of reactivity as a result of the influence of steric and electronic factors.
ASYMMETRIC DEPROTONATION BY BULI/(-)-SPARTEINE : CONVENIENT AND HIGHLY ENANTIOSELECTIVE SYNTHESES OF (S)-2-ARYL-BOC-PYRROLIDINES

Highly enantioselective syntheses of (S)-2-aryl-Boc-pyrrolidines (Boc = tert-butoxycarbonyl) can be achieved by treatment of the corresponding (arylmethyl)(3-chloropropyl)-Boc-amines with s-BuLi/(−)-sparteine. The reactions are solvent dependent with the phenyl, p-chlorophenyl, p-fluorophenyl, p-methylphenyl, m-methoxyphenyl, 1-naphthyl, and 2-naphthyl derivatives 1−7 providing 11−17 in yields of 46−75% with enantiomeric excesses of 84−96% in toluene. The 2-thienyl and 3-furyl analogs 8 and 9 afford the (S)-2-heteroaryl-Boc-pyrrolidines 18 and 19 in 51 and 21% yields with 93−96% enantiomeric excesses. The p-methoxyphenyl derivative 10 gives 20 as a racemic product in 42% yield under the same conditions. Reactions of n-BuLi/(−)-sparteine with 1 and 8 give results comparable to those with s-BuLi/(−)-sparteine. Illustrative syntheses of (S)-2-phenyl-(S)-5-methyl-Boc-pyrrolidine (22) and 1,2-(bis-(S)-2-phenylpyrrolindyl)ethane (23) are reported. The mechanism of the reaction is shown to be an asymmetric depro...
Spectroscopic Determination of Impact Sensitivities of Explosives.

A simple theory is developed which predicts impact sensitivities in crystalline explosives from vibrational spectra measured at room temperature. The theory uses Raman spectra of energetic materials to construct vibrational energy level diagrams, which are then used as input for a model designed to calculate the rate of energy transfer from phonon and near-phonon vibrational energy levels to higher energy vibrational levels. Energy transfer rates are determined using Fermi's Golden Rule and results from simple theories of near-resonant energy transfer. The application of the theory and model, using Raman spectra of seven different neat explosive samples, gives results in good agreement with results of drop weight impact tests.
The tactile receptive fields of freely moving Caenorhabditis elegans nematodes.

Sensory neurons embedded in skin are responsible for the sense of touch. In humans and other mammals, touch sensation depends on thousands of diverse somatosensory neurons. By contrast, Caenorhabditis elegans nematodes have six gentle touch receptor neurons linked to simple behaviors. The classical touch assay uses an eyebrow hair to stimulate freely moving C. elegans, evoking evasive behavioral responses. This assay has led to the discovery of genes required for touch sensation, but does not provide control over stimulus strength or position. Here, we present an integrated system for performing automated, quantitative touch assays that circumvents these limitations and incorporates automated measurements of behavioral responses. The Highly Automated Worm Kicker (HAWK) unites a microfabricated silicon force sensor holding a glass bead forming the contact surface and video analysis with real-time force and position control. Using this system, we stimulated animals along the anterior–posterior axis and compared responses in wild-type and spc-1(dn) transgenic animals, which have a touch defect due to expression of a dominant-negative α-spectrin protein fragment. As expected from prior studies, delivering large stimuli anterior and posterior to the mid-point of the body evoked a reversal and a speed-up, respectively. The probability of evoking a response of either kind depended on stimulus strength and location; once initiated, the magnitude and quality of both reversal and speed-up behavioral responses were uncorrelated with stimulus location, strength, or the absence or presence of the spc-1(dn) transgene. Wild-type animals failed to respond when the stimulus was applied near the mid-point. These results show that stimulus strength and location govern the activation of a characteristic motor program and that the C. elegans body surface consists of two receptive fields separated by a gap.
Polysulfide Ligands in Solid-State Antimony Compounds. Isolation and Structural Characterization of Cs2Sb4S8 and CsSbS6

Cs 2 Sb 4 S 8 and CsSbS 6 were synthesized by reacting Sb with a Cs 2 S x flux. An investigation of the Sb/Cs 2 S x system at 260 and 280 o C revealed the presence of two new ternary sulfides, Cs 2 Sb 4 S 8 (I) (67% yield) and CsSbS 6 (II) (69% yield), respectively. Red-orange Cs 2 Sb 4 S 8 crystallizes in the triclinic P1 space group (No. 2) with a=6.743(1) A, b=9.577(2) A, c=6.397(1) A, α=91.63(1) o , β=104.83(1) o , γ=80.57(1) o , V=392 A 3 , Z=1, and d calc =4.27g/cm 3 ; number of data with F o 2 >3σ(F o 2 ) 1889, number of variables 65, 2θ max =60 o
An acyliminium ion approach towards the synthesis of β-substituted 3,4-dihydroisoquinolone propionates

A variety of α-methoxy amides were prepared either by selective reduction of the exocyclic carbonyl of a 2-acyl-3,4-dihydroisoquinolone and subsequent trapping of the resultant α-hydroxy amide with acidic methanol or by reacting the sodium salt of 3,4-dihydroisoquinolone with a functionalized α-chloro ether. These intermediates were reacted with 1-tert-butoxy-1-tert-butyldimethylsiloxy ethene in the presence of BF3·Et2O providing access to β-substituted isoquinolone propionates in good yield.
Geometrically Constrained Tetrathiafulvalenophanes: Synthesis and Characterization

The synthesis of tetrathiafulvalenophanes 4b, 4c, 5, 9, and 10 employing two fundamentally different strategies is reported. Macrocycle 9 was obtained as a mixture of cis and trans isomers and was crystallized to afford two distinct crystals types: a red type consisting of the cis isomer and a yellow type consisting of the trans isomer. The crystal structures of cis-9 and trans-9, determined by X-ray diffraction, revealed that the cis-form possesses a planar TTF moiety while the trans-form has a distorted TTF unit. The electrochemical properties of the new tetrathiafulvalenophanes are reported.
Quantitative multi‐locus metabarcoding and waggle dance interpretation reveal honey bee spring foraging patterns in Midwest agroecosystems

We explored the pollen foraging behaviour of honey bee colonies situated in the corn and soybean dominated agroecosystems of central Ohio over a month-long period using both pollen metabarcoding and waggle dance inference of spatial foraging patterns. For molecular pollen analysis, we developed simple and cost-effective laboratory and bioinformatics methods. Targeting four plant barcode loci (ITS2, rbcL, trnL and trnH), we implemented metabarcoding library preparation and dual-indexing protocols designed to minimize amplification biases and index mistagging events. We constructed comprehensive, curated reference databases for hierarchical taxonomic classification of metabarcoding data and used these databases to train the metaxa2 DNA sequence classifier. Comparisons between morphological and molecular palynology provide strong support for the quantitative potential of multi-locus metabarcoding. Results revealed consistent foraging habits between locations and show clear trends in the phenological progression of honey bee spring foraging in these agricultural areas. Our data suggest that three key taxa, woody Rosaceae such as pome fruits and hawthorns, Salix, and Trifolium provided the majority of pollen nutrition during the study. Spatially, these foraging patterns were associated with a significant preference for forests and tree lines relative to herbaceous land cover and nonflowering crop fields.
A Suzuki cross-coupling route to substituted aziridines

Abstract We have shown that the Suzuki cross-coupling reaction of olefinic aziridines is an effective route for the synthesis of substituted aziridines. This is the first example of a palladium coupling reaction applied to an aziridine-containing molecule. This method is complementary to other methods of aziridine synthesis utilizing organocuprate reagents.
Synthesis of Hydantoins from Enantiomerically Pure α-Amino Amides without Epimerization

A method for the preparation of enantiomerically pure hydantoins from optically pure α-amino amides utilizing triphosgene is described. We also propose that the racemization observed with 1,1‘-carbonyldiimidazole (CDI) for this type of reaction is due to the imidazole carbamate intermediates.
Synthesis and Structure of the Layered Thorium Telluride CsTh2Te6

The compound CsTh(2)Te(6) has been synthesized at 800 degrees C by the reaction of Th with a Cs(2)Te(3)/Te melt as a reactive flux. The compound crystallizes in the space group -Cmcm of the orthorhombic system with two formula units in a cell of dimensions a = 4.367(2) A, b = 25.119(10) A, c = 6.140(3) A, and V = 673.5(5) A(3) at T = 113 K. The structure of CsTh(2)Te(6) has been determined from single-crystal X-ray data. The structure comprises infinite, two-dimensional double layers of ThTe(8)-bicapped trigonal prisms. The structural motif of the trigonal prisms resembles that found in UTe(2). Cs(+) cations, disordered equally over two crystallographically equivalent sites, separate the layers and are coordinated by eight Te atoms at the corners of a rectangular parallelepiped. Short Te-Te distances of 3.052(3) and 3.088(3) A form linear, infinite, one-dimensional chains within the layers. Simple formalisms describe neither the Te-Te bonding in the chain nor the oxidation state of Th. The compound shows weak semiconducting behavior along the Th/Te layers perpendicular to the Te-Te chain.
Synthesis of Cyclic cis-Enediynes from Manganese Carbyne Complexes and α,ω-Diynes

Cyclic cis-enediynes are readily prepared by a two-step one-pot procedure. The first step is the copper-catalyzed addition of α,ω-diynes to manganese carbyne complexes to give intermediate bis(alkynylcarbene) complexes that rearrange to enediyne complexes below room temperature. In the second step, the free enediyne is released from manganese by photolysis, copper-catalyzed air oxidation, or stoichiometric Cu(II) oxidation. These new procedures have been applied to a variety of five-, six-, and seven-membered-ring cyclic enediynes containing a range of ether, ester, and ketone functional groups.
Cyclization/Hydrosilylation of Functionalized Diynes Catalyzed by a Cationic Rhodium Bis(phosphine) Complex

The cationic rhodium complex [Rh(BINAP)(COD)]+ BF4- (2) [BINAP = (±)-2,2‘-bis(diphenylphosphino)binaphthyl] catalyzed the cyclization/hydrosilylation of 5,5-dicarbomethoxy-2,7-nonadiyne (1) and triethylsilane to form (E,Z)-1,1-dicarbomethoxy-3-ethylidene-4-(1-triethylsilylethylidene)cyclopentane (3) in 77% yield with ≥50:1 isomeric purity. A number of functionalized 1,6-diynes that possessed internal alkynes in addition to 1 underwent cyclization/hydrosilylation catalyzed by 2 to form silylated 1,2-dialkylidenecycloalkanes in moderate to good yield with high diastereoselectivity.
A New Method for the Synthesis of 1,2-bis(Pyrrol-2-yl)ethenes

Abstract 1,2-Bis(2-pyrryl)ethenes were synthesized in high yields by the low-valent titanium mediated reductive coupling of pyrrole-2-carboxaldehydes. The reactions of pyrrole-2-carboxaldehyde under lowvalent titanium conditions were different from those of pyrrole-3-carbonyl compounds.
Solvothermal preparation of ferromagnetic sub-micron spinel CuCr2Se4 particles

Abstract We present a simple and convenient route for the preparation of spinel CuCr2Se4 based on the solvothermal reaction of Cu2+ and Cr3+ salts with H2Se in toluene at 330 °C. H2Se required for the reaction is generated in situ by the aromatization of sitosterol by Se. Scanning electron microscopy shows particles in the 25–200 nm range agglomerating into spheroidal assemblies. The particles display the expected ferromagnetic behavior of bulk spinel CuCr2Se4. At 5 K, the saturation magnetization is found to be 2.3 μB per Cr atom, reduced from the expected spin-only value. Results of LMTO calculations on this ferromagnetic compound which is nearly half-metallic are also presented.
Computing Free-Energy Profiles Using Multidimensional Potentials of Mean Force and Polynomial Quadrature Methods

Abstract The accurate calculation of free-energy profiles for condensed-phase and enzymatic reactions is often computationally demanding when employing traditional methods such as a combined quantum and molecular mechanical (QM/MM) simulation featuring configurational sampling. A novel polynomial fitting and analytical integration method was recently developed for proton transfer reactions that provides a seven-fold enhancement to the calculation speed compared with traditional potentials of mean force (PMF) methods and yields close agreement with experimental free energies of activation. In addition, the expansion of PMF simulations to monitor three simultaneous reaction coordinates was also reported to enhance phase space sampling, which is useful for accurately elucidating complex reaction mechanisms. This review focuses upon the development of these methods and their utility is illustrated in recent examples including hydrolysis reactions in fatty acid amide hydrolase, Kemp elimination reactions in antibody 4B2 and ionic liquid environments, and condensed-phase singlet oxygen ene reactions.
Second Harmonic Generation Properties of Fluorescent Polymer-Encapsulated Gold Nanoparticles

Center for Biomedical Imaging Technology andDepartment of PhysiologyUniVersity of Connecticut Health CenterFarmington, Connecticut 06030DiVision of Applied Physics, Hebrew UniVersityJerusalem, IsraelReceiVed June 22, 2000It has been known for some time that second harmonicgeneration (SHG) can be greatly enhanced (˘10
Unmet needs for analyzing biological big data: A survey of 704 NSF principal investigators

In a 2016 survey of 704 National Science Foundation (NSF) Biological Sciences Directorate principal investigators (BIO PIs), nearly 90% indicated they are currently or will soon be analyzing large data sets. BIO PIs considered a range of computational needs important to their work, including high performance computing (HPC), bioinformatics support, multistep workflows, updated analysis software, and the ability to store, share, and publish data. Previous studies in the United States and Canada emphasized infrastructure needs. However, BIO PIs said the most pressing unmet needs are training in data integration, data management, and scaling analyses for HPC-acknowledging that data science skills will be required to build a deeper understanding of life. This portends a growing data knowledge gap in biology and challenges institutions and funding agencies to redouble their support for computational training in biology.
The preparation and reactions of protected glyphosate imidate, thioimidate, and thiono esters from N-[diphenoxyphosphinylmethyl]glycinonitrile: Comparative reactivities of activated carboxylate versus phosphonate esters†

The highly efficient syntheses of novel protected glyphosate imidate, thioimidate, and thiono ester derivatives are described starting from N-[diphenoxyphosphinylmethyl]glycinonitrile 3b. The scope, utility and limitations in using each of these activated carboxylate functionalities for further transformations to new “masked” heterocyclic derivatives are defined. While the solution stability of the imidate and thioimidate series limited the synthetic application of these species, the corresponding thiono ester derivatives were valuable synthetic intermediates, providing a short, efficient route to the first glyphosate derivatives containing 1,3,4-oxadiazole and 1,2,4-triazole ring systems in place of the carboxylate group. These thiono esters thus undergo selective nucleophilic addition at this activated carboxylate center, while retaining the reactive diphenyl phosphonate moiety.
Diastereoselective acetylide additions to a [3.2.1]-dioxabicyclooctanone: Installation of the C(4) stereocenter of (+)-zaragozic acid C

Abstract Nucleophilic addition of lithium acetylides to ketone 2 provides a key intermediate in the synthesis of (+)-zaragozic acid C. The effect of co-solvents (tertiary amines) and additives (LiBr) on the diastereoselection of this reaction has been investigated.
FUSTr: a tool to find gene families under selection in transcriptomes

Background The recent proliferation of large amounts of biodiversity transcriptomic data has resulted in an ever-expanding need for scalable and user-friendly tools capable of answering large scale molecular evolution questions. FUSTr identifies gene families involved in the process of adaptation. This is a tool that finds genes in transcriptomic datasets under strong positive selection that automatically detects isoform designation patterns in transcriptome assemblies to maximize phylogenetic independence in downstream analysis. Results When applied to previously studied spider transcriptomic data as well as simulated data, FUSTr successfully grouped coding sequences into proper gene families as well as correctly identified those under strong positive selection in relatively little time. Conclusions FUSTr provides a useful tool for novice bioinformaticians to characterize the molecular evolution of organisms throughout the tree of life using large transcriptomic biodiversity datasets and can utilize multi-processor high-performance computational facilities.
Approaches to unsaturated analogues of nucleosides comprising four- and six-membered rings.

Unsaturated nucleoside analogues 21, 22, 46, and 54, comprising four- and six-membered rings, were synthesized using two different approaches. The 2-benzyloxycycloalkanones 23a and 23b served as starting materials for both methods. Conversion to methylenecyclobutanes 29a and 29b was followed by addition of bromine via pyridinium perbromide to give vicinal dibromides 30a and 30b. Reaction of 29a with Br2 gave a ring-contracted cyclopropane derivative 31. Alkylation−elimination of adenine with 30a gave bromoalkene 32 as the major product and adenine-containing unsaturated derivatives 33, 34, and 35 as minor components. Vicinal dibromide 30b gave the Zaitsev cyclohexene 45 as the only product. Epoxidation of 29a and 29b afforded oxiranes 36a and 36b which were used in alkylation of adenine to furnish hydroxy derivatives 37a, 37b, 38a, and 38b. β-Elimination via mesylates 39a and 40a using tBuOK/DMF gave Z- and E-methylenecyclobutanes 34 and 35. With an excess of base the E-bis-methylenecyclobutane 41 was obt...
Inhibition of DNA Topoisomerase II by Azaelliptitoxins Functionalized in the Variable Substituent Domain

A series of novel C11-substituted derivatives of azaelliptitoxin (azatoxin) have been synthesized and tested for their inhibitory activity against human DNA topoisomerase II. Incorporation of a C11 polyamine or amine resulted in an increase in the intercalation properties of the drug and a decrease of topoisomerase II activity. The structure-activity relationship (SAR) profile of the nonintercalating C11 anilino azatoxin class follows the SAR of the (anilino)acridine family. 11-(4-Cyanoanilino)azatoxin (14) was found to be the most active analog in this series, exhibiting approximately 10-fold higher activity than azatoxin 12 and etoposide.
User-Guided Clustering in Heterogeneous Information Networks via Motif-Based Comprehensive Transcription

Heterogeneous information networks (HINs) with rich semantics are ubiquitous in real-world applications. For a given HIN, many reasonable clustering results with distinct semantic meaning can simultaneously exist. User-guided clustering is hence of great practical value for HINs where users provide labels to a small portion of nodes. To cater to a broad spectrum of user guidance evidenced by different expected clustering results, carefully exploiting the signals residing in the data is potentially useful. Meanwhile, as one type of complex networks, HINs often encapsulate higher-order interactions that reflect the interlocked nature among nodes and edges. Network motifs, sometimes referred to as meta-graphs, have been used as tools to capture such higher-order interactions and reveal the many different semantics. We therefore approach the problem of user-guided clustering in HINs with network motifs. In this process, we identify the utility and importance of directly modeling higher-order interactions without collapsing them to pairwise interactions. To achieve this, we comprehensively transcribe the higher-order interaction signals to a series of tensors via motifs and propose the MoCHIN model based on joint non-negative tensor factorization. This approach applies to arbitrarily many, arbitrary forms of HIN motifs. An inference algorithm with speed-up methods is also proposed to tackle the challenge that tensor size grows exponentially as the number of nodes in a motif increases. We validate the effectiveness of the proposed method on two real-world datasets and three tasks, and MoCHIN outperforms all baselines in three evaluation tasks under three different metrics. Additional experiments demonstrated the utility of motifs and the benefit of directly modeling higher-order information especially when user guidance is limited. (The code and the data are available at https://github.com/NoSegfault/MoCHIN.)
A Systematic Literature Review of the Current State of Knowledge Related to Interventions for Bereaved Parents.

Aims:The purpose of this systematic literature review is to describe the interventions for bereaved parents, evaluate intervention effectiveness through study methodology rigor, replicability, and ...
How to build a fast and highly sensitive sound detector that remains robust to temperature shifts

Frogs must have sharp hearing abilities during the warm summer months to successfully find mating partners. This study aims to understand how frog hair cell ribbon-type synapses preserve both sensitivity and temporal precision during temperature changes. Under room (∼24°C) and high (∼32°C) temperature, we performed in vitro patch-clamp recordings of hair cells and their afferent fibers in amphibian papillae of either male or female bullfrogs. Afferent fibers exhibited a wide heterogeneity in membrane input resistance (Rin) from 100 mΩ to 1000 mΩ, which may contribute to variations in spike threshold and firing frequency. At higher temperatures, most fibers increased their frequency of spike firing due to an increase in spontaneous EPSC frequencies. Hair cell resting membrane potential (Vrest) remained surprisingly stable during temperature increases, because Ca2+ influx and K+ outflux increased simultaneously. This increase in Ca2+ current likely enhanced spontaneous EPSC frequencies. These larger "leak currents" at Vrest also lowered Rin and produced higher electrical resonant frequencies. Lowering Rin will reduce the hair cells receptor potential and presumably moderate the systems sensitivity. Using membrane capacitance measurements, we suggest that hair cells can partially compensate for this reduced sensitivity by increasing exocytosis efficiency and the size of the readily releasable pool of synaptic vesicles. Furthermore, paired recordings of hair cells and their afferent fibers showed that synaptic delays shortened and multivesicular release becomes more synchronous at higher temperatures, which should improve temporal precision. Together, our results explain many previous in vivo observations on the temperature dependence of spikes in auditory nerves.SIGNIFICANCE STATEMENT The vertebrate inner ear detects and transmits auditory information over a broad dynamic range of sound frequency and intensity. It achieves remarkable sensitivity to soft sounds and precise frequency selectivity. How does the ear of cold-blooded vertebrates maintain its performance level as temperature changes? More specifically, how does the hair cell to afferent fiber synapse in bullfrog amphibian papilla adjust to a wide range of physiological temperatures without losing its sensitivity and temporal fidelity to sound signals? This study uses in vitro experiments to reveal the biophysical mechanisms that explain many observations made from in vivo auditory nerve fiber recordings. We find that higher temperature facilitates vesicle exocytosis and electrical tuning to higher sound frequencies, which benefits sensitivity and selectivity.
Motivic random variables and representation stability II: Hypersurface sections

Abstract We prove geometric and cohomological stabilization results for the universal smooth degree d hypersurface section of a fixed smooth projective variety as d goes to infinity. We show that relative configuration spaces of the universal smooth hypersurface section stabilize in the completed Grothendieck ring of varieties, and deduce from this the stabilization of the Hodge Euler characteristic of natural families of local systems constructed from the vanishing cohomology. We prove explicit formulas for the stable values using a probabilistic interpretation, along with the natural analogs in point counting over finite fields. We explain how these results provide new geometric examples of a weak version of representation stability for symmetric, symplectic, and orthogonal groups. This interpretation of representation stability was studied in the prequel [20] for configuration spaces.
Mind Your Credit: Assessing the Health of the Ripple Credit Network

The Ripple credit network has emerged as a payment backbone with key advantages for financial institutions and the remittance industry. Its path-based IOweYou (IOU) settlements across different (crypto)currencies conceptually distinguishes the Ripple blockchain from cryptocurrencies (such as Bitcoin and altcoins), and makes it highly suitable to an orthogonal yet vast set of applications in the remittance world for cross-border transactions and beyond. This work studies the structure and evolution of the Ripple network since its inception, and investigates its vulnerability to devilry attacks that affect the IOU credit of linnet users» wallets. We find that about 13M USD are at risk in the current Ripple network due to inappropriate configuration of the rippling flag on credit links, facilitating undesired redistribution of credit across those links. Although the Ripple network has grown around a few highly connected hub (gateway) wallets that constitute the core of the network and provide high liquidity to users, such a credit link distribution results in a user base of around 112,000 wallets that can be financially isolated by as few as 10 highly connected gateway wallets. Indeed, today about 4.9M USD cannot be withdrawn by their owners from the Ripple network due to PayRoutes, a gateway tagged as faulty by the Ripple community. Finally, we observe that stale exchange offers pose a real problem, and exchanges (market makers) have not always been vigilant about periodically updating their exchange offers according to current real-world exchange rates. For example, stale offers were used by 84 Ripple wallets to gain more than 4.5M USD from mid-July to mid-August 2017. Our findings should prompt the Ripple community to improve the health of the network by educating its users on increasing their connectivity, and by appropriately maintaining the credit limits, rippling flags, and exchange offers on their IOU credit links.
Neutron Electric Dipole Moment from quark Chromoelectric Dipole Moment

The connection between a regularization-independent symmetric momentum substraction (RI˜ SMOM) and the MS scheme for the quark chromo EDM operators is discussed. A method for evaluating the neutron EDM from quark chromoEDM is described. A preliminary study of the signal in the matrix element using clover quarks on a highly improved staggered quark (HISQ) ensemble is shown.
Algebraic spiral solutions of 2d incompressible Euler

Abstract We consider self-similar solutions of the 2d incompressible Euler equations. We construct a class of solutions with vorticity forming algebraic spirals near the origin, in analogy to vortex sheets rolling up into algebraic spirals.
From quantum Schubert polynomials to k-Schur functions via the Toda lattice

We show that Lapointe-Lascoux-Morse k-Schur functions (at t=1) and Fomin-Gelfand-Postnikov quantum Schubert polynomials can be obtained from each other by a rational substitution. This is based upon Kostant's solution of the Toda lattice and Peterson's work on quantum Schubert calculus.
Cloud radio access meets heterogeneous small cell networks: A cognitive hierarchy perspective

In this paper, the problem of distributed power allocation is considered for the downlink of a cloud radio access network (CRAN) that is coexisting with a heterogeneous network. In this multi-tier system, the heterogeneous network base stations (BSs) as well as the CRAN remote radio heads seek to choose their optimal power to maximize their users' rates. The problem is formulated as a noncooperative game in which the players are the CRAN's cloud and the BSs. Given the difference of capabilities between the CRAN and the various BSs, the game is cast within the framework of cognitive hierarchy theory. In this framework, players are organized in a hierarchy in such a way that a player can choose its strategy while considering players of only similar or lower hierarchies. Using such a hierarchical design, one can reduce the interference caused by the CRAN and high-powered base stations on low-powered BSs. For this game, the properties of the Nash equilibrium and the cognitive hierarchy equilibrium are analyzed. Simulation results show that the proposed cognitive hierarchy model yields significant performance gains, in terms of the total rate, reaching up to twice the rate achieved by a classical noncooperative game's Nash equilibrium.
Sparse operator compression of higher-order elliptic operators with rough coefficients

We introduce the sparse operator compression to compress a self-adjoint higher-order elliptic operator with rough coefficients and various boundary conditions. The operator compression is achieved by using localized basis functions, which are energy minimizing functions on local patches. On a regular mesh with mesh size h, the localized basis functions have supports of diameter O(hlog(1/h)) and give optimal compression rate of the solution operator. We show that by using localized basis functions with supports of diameter O(hlog(1/h)), our method achieves the optimal compression rate of the solution operator. From the perspective of the generalized finite element method to solve elliptic equations, the localized basis functions have the optimal convergence rate O(h^k)for a (2k)th-order elliptic problem in the energy norm. From the perspective of the sparse PCA, our results show that a large set of Matern covariance functions can be approximated by a rank-n operator with a localized basis and with the optimal accuracy.
Shear driven formation of nano-diamonds at sub-gigapascals and 300 K

The transformation pathways of carbon at high pressures are of broad interest for synthesis of novel materials and for revealing the Earth's geological history. We have applied large plastic shear on graphite in a rotational anvil cell to form hexagonal diamond and nanocrystalline cubic diamond at extremely low pressures of 0.4 and 0.7 GPa, which are 50 and 100 times lower than the transformation pressures under hydrostatic compression and well below the phase equilibrium. Large shearing accompanied with pressure elevation to 3 GPa also leads to formation of a new orthorhombic diamond phase. Our results demonstrate new mechanisms and new means for plastic shear-controlled material synthesis at drastically reduced pressures, enabling new technologies for material synthesis. The result also has significant geological implications.
Tight Piecewise Convex Relaxations for Global Optimization of Optimal Power Flow

Since the alternating current optimal power flow (ACOPF) problem was introduced in 1962, developing efficient solution algorithms for the problem has been an active field of research. In recent years, there has been increasing interest in convex relaxations-based solution approaches that are often tight in practice. Based on these approaches, we develop tight piecewise convex relaxations with convex-hull representations, an adaptive, multivariate partitioning algorithm with bound tightening that progressively improves these relaxations and, given sufficient time, converges to the globally optimal solution. We illustrate the strengths of our algorithm using benchmark ACOPF test cases from the literature. Computational results show that our novel algorithm reduces the best-known optimality gaps for some hard ACOPF cases.
Multi-UAV Continuum Deformation Flight Optimization in Cluttered urban environments

This paper studies collective motion optimization of a fleet of UAVs flying over a populated and geometrically constrained area. The paper treats UAVs as particles of a deformable body, thus, UAV coordination is defined by a homeomorphic continuum deformation function. Under continuum deformation, the distance between individual UAVs can significantly change while assuring the UAVs dont collide, enabling a swarm to travel through the potentially cluttered environment. To ensure inter-agent and obstacle collision avoidance, the paper formulates safety requirements as inequality constraints of the coordination optimization problem. The main objective of the paper is then to optimize continuum deformation of the UAV team satisfying all continuum deformation inequality constraints. Given initial and target configurations, the cost is defined as a weighted sum of the travel distance and distributed cost proportional to the likelihood of the human presence
Photonic Chern insulator through homogenization of an array of particles

We propose a route towards creating a photonic Chern insulator through homogenization with an array of gyromagnetic cylinders. The non-trivial band topology of such a system is independent of the lattice structure.
Motion of sets by curvature and derivative of capacity potential

Abstract We study a geometric flow where the motion of a set is driven by the mean curvature of its boundary and the normal derivative of its capacity potential. We establish local well-posedness and propose two possible weak formulations that exist after singularities.
Random Shuffling Beats SGD after Finite Epochs

A long-standing problem in the theory of stochastic gradient descent (SGD) is to prove that its without-replacement version RandomShuffle converges faster than the usual with-replacement version. We present the first (to our knowledge) non-asymptotic solution to this problem, which shows that after a "reasonable" number of epochs RandomShuffle indeed converges faster than SGD. Specifically, we prove that under strong convexity and second-order smoothness, the sequence generated by RandomShuffle converges to the optimal solution at the rate O(1/T^2 + n^3/T^3), where n is the number of components in the objective, and T is the total number of iterations. This result shows that after a reasonable number of epochs RandomShuffle is strictly better than SGD (which converges as O(1/T)). The key step toward showing this better dependence on T is the introduction of n into the bound; and as our analysis will show, in general a dependence on n is unavoidable without further changes to the algorithm. We show that for sparse data RandomShuffle has the rate O(1/T^2), again strictly better than SGD. Furthermore, we discuss extensions to nonconvex gradient dominated functions, as well as non-strongly convex settings.
Random matrix ensembles with split limiting behavior

We introduce a new family of N × N random real symmetric matrix ensembles, the k-checkerboard matrices, whose limiting spectral measure has two components which can be determined explicitly. All bu...
Optimal Multicasting in Hybrid RF/FSO DTNs

The multi-copy routing paradigm in Delay Tolerant Networks (DTNs) implies that increasing contact bandwidth leads to a decrease in data delivery delay and an improvement in throughput. With Hybrid Radio Frequency/Free Space Optical (RF/FSO) PHY layers, the high data rate FSO links can be used to increase the contact bandwidth. However, due to the highly directional nature of FSO links, broadcasting is difficult. A naive broadcast strategy where the beam divergence angle is increased to include many nodes in the broadcast set results in low data rate, and does not always result in the minimum achievable delay. In this work we develop an optimal multicast algorithm for hybrid RF/FSO networks. We show that the problem is an abstraction of the minimum weight set cover problem which is known to be NP- hard. A computationally cheap greedy local optimum heuristic is proposed. A comprehensive evaluation using delay, throughput and computation time as metrics is performed using various solutions. These extensive evaluations show that our solution outperforms both naive broadcast and multiple unicast, taking 95% less time as compared to the exact algorithm, while providing comparable performance.
Bayesian Optimization of Combinatorial Structures

The optimization of expensive-to-evaluate black-box functions over combinatorial structures is an ubiquitous task in machine learning, engineering and the natural sciences. The combinatorial explosion of the search space and costly evaluations pose challenges for current techniques in discrete optimization and machine learning, and critically require new algorithmic ideas. This article proposes, to the best of our knowledge, the first algorithm to overcome these challenges, based on an adaptive, scalable model that identifies useful combinatorial structure even when data is scarce. Our acquisition function pioneers the use of semidefinite programming to achieve efficiency and scalability. Experimental evaluations demonstrate that this algorithm consistently outperforms other methods from combinatorial and Bayesian optimization.
Single and population coding of taste in the gustatory cortex of awake mice.

Here, we analyzed taste-related spiking activity in awake mouse gustatory cortical (GC) neural ensembles, revealing deep similarities between mouse cortical taste processing and that repeatedly dem...
Phase Transition for Accessibility Percolation on Hypercubes

In this paper, we consider accessibility percolation on hypercubes, i.e., we place i.i.d. uniform [0, 1] random variables on vertices of a hypercube, and study whether there is a path connecting two vertices such that the values of these random variables increase along the path. We establish a sharp phase transition depending on the difference of the values at the two endpoints and determine the critical window of the phase transition. Our result completely resolves a conjecture of Berestycki et al. (Accessibility percolation with backsteps. Preprint, available at http://arxiv.org/abs/1401.6894 ).
Extension groups for DG modules

ABSTRACTLet M and N be differential graded (DG) modules over a positively graded commutative DG algebra A. We show that the Ext-groups ExtAi(M,N) defined in terms of semi-projective resolutions are not in general isomorphic to the Yoneda Ext-groups YExtAi(M,N) given in terms of equivalence classes of extensions. On the other hand, we show that these groups are isomorphic when the first DG module is semi-projective.
Quantifying performance of bipedal standing with multi-channel EMG

Spinal cord stimulation has enabled humans with motor complete spinal cord injury (SCI) to independently stand and recover some lost autonomic function. Quantifying the quality of bipedal standing under spinal stimulation is important for spinal rehabilitation therapies and for new strategies that seek to combine spinal stimulation and rehabilitative robots (such as exoskeletons) in real time feedback. To study the potential for automated electromyography (EMG) analysis in SCI, we evaluated the standing quality of paralyzed patients undergoing electrical spinal cord stimulation using both video and multi-channel surface EMG recordings during spinal stimulation therapy sessions. The quality of standing under different stimulation settings was quantified manually by experienced clinicians. By correlating features of the recorded EMG activity with the expert evaluations, we show that multi-channel EMG recording can provide accurate, fast, and robust estimation for the quality of bipedal standing in spinally stimulated SCI patients. Moreover, our analysis shows that the total number of EMG channels needed to effectively predict standing quality can be reduced while maintaining high estimation accuracy, which provides more flexibility for rehabilitation robotic systems to incorporate EMG recordings.
Early Stopping for Nonparametric Testing

Early stopping of iterative algorithms is an algorithmic regularization method to avoid over-fitting in estimation and classification. In this paper, we show that early stopping can also be applied to obtain the minimax optimal testing in a general non-parametric setup. Specifically, a Wald-type test statistic is obtained based on an iterated estimate produced by functional gradient descent algorithms in a reproducing kernel Hilbert space. A notable contribution is to establish a ``sharp'' stopping rule: when the number of iterations achieves an optimal order, testing optimality is achievable; otherwise, testing optimality becomes impossible. As a by-product, a similar sharpness result is also derived for minimax optimal estimation under early stopping. All obtained results hold for various kernel classes, including Sobolev smoothness classes and Gaussian kernel classes.
Finitely balanced sequences and plasticity of 1-dimensional tilings ☆

Abstract We relate a balancing property of letters for bi-infinite sequences to the invariance of the resulting 1-dimensional tiling dynamics under changes in the lengths of the tiles. If the language of the sequence space is finitely balanced, then all length changes in the corresponding tiling space result in topological conjugacies, up to an overall rescaling.
A Wireless Triboelectric Nanogenerator

A new “wireless” paradigm for harvesting mechanical energy via a 3D-printed wireless triboelectric nanogenerator (W-TENG) comprised of an ecofriendly graphene polylactic acid (gPLA) nanocomposite and Teflon is demonstrated. The W-TENG generates very high output voltages >2 kV with a strong electric field that enables the wireless transmission of harvested energy over a distance of 3 m. The W-TENG exhibited an instantaneous peak power up to 70 mW that could be wirelessly transmitted for storage into a capacitor obviating the need for hard-wiring or additional circuitry. Furthermore, the use of W-TENG for wireless and secure actuation of smart-home applications such as smart tint windows, temperature sensors, liquid crystal displays, and security alarms either with a single or a specific user-defined passcode of mechanical pulses (e.g., Fibonacci sequence) is demonstrated. The scalable additive manufacturing approach for gPLA-based W-TENGs, along with their high electrical output and unprecedented wireless applications, is poised for revolutionizing the present mechanical energy harvesting technologies.
Brownian bricklayer: A random space-filling curve

Abstract Let ( B ( t ) , t ≥ 0 ) denote the standard, one-dimensional Wiener process and ( l ( y , t ) ; y ∈ R , t ≥ 0 ) its local time at level y up to time t . Then ( ( B ( t ) , l ( B ( t ) , t ) ) , t ≥ 0 ) is a random, continuous path that fills the upper half-plane, covering one unit of area per unit time.