cssi/SciSciGPT-SciSciNet huggingface dataset:
Nambu-Goldstone Modes in Gravitational Theories with Spontaneous Lorentz Breaking

Spontaneous breaking of Lorentz symmetry has been suggested as a possible mechanism that might occur in the context of a fundamental Planck-scale theory, such as string theory or a quantum theory of gravity. However, if Lorentz symmetry is spontaneously broken, two sets of questions immediately arise: What is the fate of the Nambu–Goldstone (NG) modes, and can a Higgs mechanism occur? A brief summary of some recent work looking at these questions is presented here.
Total synthesis of (±)-ginkgolide B

Ginkgo biloba, termed the “living fossil” by Darwin, has ancestors dating to 230 million B.C.1 Extracts of Ginkgo biloba, which have been used as herbal medicines for 5000 years to treat a variety of conditions such as coughs, asthma, and circulatory disorders, are currently undergoing clinical evaluation for treatment of dementia.2 Ginkgolide B is the most potent platelet activating factor (PAF) antagonist of the ginkgo extracts, with an IC50 of 0.6 μM.3 The complex molecular architecture of ginkgolide B, which includes six rings, eleven stereogenic centers, ten oxygenated carbons, and four contiguous fully substituted carbons, is a daunting challenge for chemical synthesis. The diabolical disposition of functionality dictates that introduction of functional groups be judiciously orchestrated. The ginkgolides were first characterized in 1967,4 and the syntheses of ginkgolides A5 and B6 were reported by Corey and co-workers in 1988. The synthesis of the related compound, bilobalide, was also achieved by the Corey group7 as well as by our laboratory.8 Reported herein is the total synthesis of ginkgolide B utilizing the zinc-copper homoenolate9 and double diastereoselective intramolecular [2+2] photocycloaddition methodologies developed in our laboratories.10 Strategically, the synthesis of ginkgolide B was thought to be achievable from the pentacyclic precursor 2 which was to be derived from 3 by a regioselective cyclobutane fragmentation and further functionalization. A stereoselective intramolecular photocycloaddition of the enone-furan 4 to produce cycloadduct 3 was anticipated to provide the stereochemical control required to construct the congested core of the molecule. Preparation of the photocycloaddition substrate 4 was to be accomplished through our homoenolate technology for the construction of carboalkoxycyclopentenones.9 The synthesis of the photocycloadduct 3 is illustrated in Scheme 2. Ethyl 3-(3-furyl)acrylate8 was subjected to the higher order cuprate [t-Bu2CuCNLi2, TMSCl, Et2O] to incorporate the critical tert-butyl group. The resultant ester was reduced with i-Bu2AlH to provide the corresponding aldehyde 5 in 95% overall yield. Addition of ethynylmagnesium bromide to aldehyde 5 gave a 1.2:1
Continuous-time quantum search and time-dependent two-level quantum systems

It was recently emphasized by Byrnes, Forster and Tessler [Phys. Rev. Lett. 120 (2018) 060501] that the continuous-time formulation of Grover’s quantum search algorithm can be intuitively understoo...
An intramolecular azomethine ylide–alkene cycloaddition approach to pyrrolo[3,2-c]quinolines-synthesis of a C2-truncated martinelline model

Abstract The hexahydropyrrolo[3,2-c]quinoline core found in the Martinella alkaloids was constructed through an intramolecular [3+2] azomethine ylide–alkene cycloaddition. Some chemical manipulations of the tricycle are reported.
2′-Deoxyadenylyl-(3′→5′)-isodideoxyadenosine, a unique dinucleotide: Synthesis, enzymology, and conformational studies

Abstract The synthesis, enzymatic stability toward nucleases, and conformational properties of a unique dinucleotide, 2′-deoxyadenylyl-(3′→5′)-isodideoxyadenosine (2), a model system for the terminus of HIV viral DNA on incorporation of the L-related isomeric dideoxynucleoside, (S,S)-IsoddA, is reported. This is the first example of a dinucleotide bearing an isomeric nucleoside component.
Synthesis of silicon containing alanines

Abstract The synthesis of silicon containing alanines in optically pure form from an electrophilic alaninol synthon is described. The overall chemical yields for the synthesis of the novel amino acids range from 19–39%.
Organic synthesis using chemical tags: the third Leg of parallel synthesis.

Increasing emphasis has recently been placed on the development of synthetic methods which effectively couple chemical synthesis and purification. For example, new formats for parallel synthesis are being developed which involve attachment of chemical tags to both reagents, reactants, and substrates to permit their chemoselective removal from reaction mixtures. The driving force for the development of tagged organic reagents is the ability to use standard solution-phase chemistry methods and reaction monitoring techniques (e.g. TLC and HPLC). In this mini-review, we will outline recent developments on the growing class of chemically tagged reagents, reactants, and substrates and highlight examples of their use in multistep synthesis.
OSCA/TMEM63 are an Evolutionarily Conserved Family of Mechanically Activated Ion Channels.

Mechanically activated (MA) ion channels convert physical forces into electrical signals, and are essential for eukaryotic physiology. Despite their importance, few bona-fide MA channels have been described in plants and animals. Here, we show that various members of the OSCA and TMEM63 family of proteins from plants, flies, and mammals confer mechanosensitivity to naive cells. We conclusively demonstrate that OSCA1.2, one of the Arabidopsis thaliana OSCA proteins, is an inherently mechanosensitive, pore-forming ion channel. Our results suggest that OSCA/TMEM63 proteins are the largest family of MA ion channels identified, and are conserved across eukaryotes. Our findings will enable studies to gain deep insight into molecular mechanisms of MA channel gating, and will facilitate a better understanding of mechanosensory processes in vivo across plants and animals.
A catalytic reaction of alkynes via multiple-site functionalization

The first multiple-site activation of alkynes with amine/halogen functionalities has been established. The reaction was performed by treating alkyne with N,N-dichlorobenzenesulfonamide at 80 degrees C in the presence of palladium acetate catalyst. A new mechanism was proposed which involves the novel formation of beta-halovinyl palladium and pi-allylpalladium species. Excellent regio- and stereoselectivities were achieved with the absolute structure determined by X-ray structural analysis.
Ordered CoSn-type ternary phases in Co3Sn3−xGex

Abstract CoSn is the prototype compound of the B35 structure, which has long been of interest due to its rarity and unusually low packing density. We report the synthesis and properties of the solid solution Co3Sn3−xGex for 0 ⩽ x ⩽ 2, in order to clarify the conditions necessary to stabilize such a phase. By taking advantage of the chemical differences between the two crystallographically inequivalent Sn sites in the structure, we observe ordered ternary phases, nominally Co3SnGe2 and Co3Sn2Ge. The electron count and unit cell configuration remain unchanged from CoSn; these observations thus help to clarify some ambiguities about the stabilizing forces in this crystal structure. All compounds are normal metals with room temperature conductivities ranging from 5 to 50 μΩ cm and are weakly paramagnetic.
Transition metal dihydrogen complexes: isotope effects on reactivity and structure†

Complexation of dihydrogen to transition metal centers was discovered by Kubas and coworkers in 1984. The notion that the simplest molecule in chemistry can act as a ligand to form relatively stable transition metal complexes has led to a paradigm shift in coordination chemistry. Crucial to the exploration of this intriguing new chemistry has been the use of isotope substitution. Several aspects of the coordination chemistry of dihydrogen have revealed fascinating isotope effects on reactivity, spectroscopy and in some cases structure. Complexation of HD has been used to diagnose bond distances from measurements of JHD and isotope effects for D2 versus H2 binding have been evaluated. Examples of quantum mechanical exchange coupling in H2 complexes have been described. These effects disappear when one of the H atoms is replaced by D. In molecules with bound hydrogen adjacent to a hydride ligand, non-statistical occupancy of hydrogen versus hydride sites by deuterons has been observed. In some cases, isotope-dependent structures have been established by the study of HD, HT and DT complexes using NMR spectroscopy. Copyright © 2007 John Wiley & Sons, Ltd.
New zirconium kappa phases

The compounds Zr9W4S, Zr9Mo4S, and Zr9W4S1−xNixO3 have been prepared by high temperature techniques. They belong to the general group of K phases. Single crystal x-ray diffraction analysis of the mixed nickel/sulfide (Zr9.2W3.8S0.7Ni0.3O3.0, R = 2.6%) reveals nickel substitution for sulfur, and confirms oxygen occupancy of interstitial sites. Neue Zirconium Kappa-Phasen Die Verbindungen Zr9W4S, Zr9Mo4S und Zr9W4S1−xNixO3 wurden bei hohen Temperaturen dargestellt. Sie gehoren zur allgemeinen Gruppe der K-Phasen. Einkristall-Rontgenanalyse der Nickel/Sulfidenthaltenden Verbindung (Zr9.2W3.8S0.7Ni0.3O3.0, R = 2,6%) zeigt Substitution von Schwefel durch Nickel und bestatigt die Besetzung interstitieller Zentren durch Sauerstoff.
Cascade iminium ion reactions for the facile synthesis of quinolizidines. Concise syntheses of (+/-)-epilupinine and (-)-epimyrtine.

Several novel cascade processes have been designed and developed that involve sequential reactions of imines and iminium ions to form substituted quinolizidine ring systems in a single step from simple and readily available starting materials. The utility and promise of these cascade reactions is evident from their application to extraordinarily concise syntheses of the representative quinolizidine alkaloids (±)-epilupinine and (−)-epimyrtine.
An agent-based model of cattle grazing toxic Geyer's larkspur.

By killing cattle and otherwise complicating management, the many species of larkspur (Delphinium spp.) present a serious, intractable, and complex challenge to livestock grazing management in the western United States. Among the many obstacles to improving our understanding of cattle-larkspur dynamics has been the difficulty of testing different grazing management strategies in the field, as the risk of dead animals is too great. Agent-based models (ABMs) provide an effective method of testing alternate management strategies without risk to livestock. ABMs are especially useful for modeling complex systems such as livestock grazing management, and allow for realistic bottom-up encoding of cattle behavior. Here, we introduce a spatially-explicit, behavior-based ABM of cattle grazing in a pasture with a dangerous amount of Geyer’s larkspur (D. geyeri). This model tests the role of herd cohesion and stocking density in larkspur intake, finds that both are key drivers of larkspur-induced toxicosis, and indicates that alteration of these factors within realistic bounds can mitigate risk. Crucially, the model points to herd cohesion, which has received little attention in the discipline, as playing an important role in lethal acute toxicosis. As the first ABM to model grazing behavior at realistic scales, this study also demonstrates the tremendous potential of ABMs to illuminate grazing management dynamics, including fundamental aspects of livestock behavior amidst ecological heterogeneity.
Cost-efficient high throughput capture of museum arthropod specimen DNA using PCR-generated baits

Gathering genetic data for rare species is one of the biggest remaining obstacles in modern phylogenetics, particularly for megadiverse groups such as arthropods. Next generation sequencing techniques allow for sequencing of short DNA fragments contained in preserved specimens >20 years old, but approaches such as whole genome sequencing are often too expensive for projects including many taxa. Several methods of reduced representation sequencing have been proposed that lower the cost of sequencing per specimen, but many remain costly because they involve synthesizing nucleotide probes and target hundreds of loci. These datasets are also frequently unique for each project and thus generally incompatible with other similar datasets. Here, we explore utilization of in-house generated DNA baits to capture commonly utilized mitochondrial and ribosomal DNA loci from insect museum specimens of various age and preservation types without the a priori need to know the sequence of the target loci. Both within species and cross-species capture are explored, on preserved specimens ranging in age from one to 54 years old. We found most samples produced sufficient amounts of data to assemble the nuclear ribosomal rRNA genes and near complete mitochondrial genomes and produce well-resolved phylogenies in line with expected results. The dataset obtained can be straightforwardly combined with the large cache of existing Sanger-sequencing-generated data built up over the past 30 years and targeted loci can be easily modified to those commonly used in different taxa. Furthermore, the protocol we describe allows for inexpensive data generation (as low as ~$35/sample), of at least 20 kilobases per specimen, for specimens at least as old as ~1965, and can be easily conducted in most laboratories. If widely applied, this technique will accelerate the accurate resolution of the Tree of Life especially on non-model organisms with limited existing genomic resources.
Influence of Mismarking Fiducial Locations on EEG Source Estimation

Mismarking locations of the fiducials can have a significant influence on the digitized electrode locations and cortical source estimation using high-density EEG. Understanding and quantifying how uncertainties in the fiducial locations affect the locations of cortical sources is important for interpreting EEG analyses. We systematically shifted fiducial locations to investigate the relationship between variations of fiducial locations and the corresponding estimations of the source locations. We quantified the uncertainty of the dipole locations using the enclosing volume of the dipole locations and the maximum width of the dipole cluster. Shifting fiducial locations 1.5 cm increased the uncertainty of the dipole locations to span a volume >1 cm3 and about 2.5 cm wide. Results suggest that the fiducials need to be digitized accurately within at least 0.5 cm of the absolute actual fiducial location to limit the uncertainty of a dipole location to <1 cm. Additionally, we used random fiducial shift combinations to estimate the effects of combinations of the fiducial shifts on dipole location estimation. This analysis showed that dipole locations were within the bounds of our dipole estimation uncertainty volumes. Based on the outcomes, we suggest marking fiducials carefully before placement of the cap and to use a digitization method with an accuracy of <0.5 cm.
Syntheses and characterization of aromatic secondary and tertiary amines and a new imidazolone from dicyanoimidazole

Abstract Aromatic primary amines substituted with electron donating groups such as methoxy and methyl at the para position undergo nucleophilic aromatic substitution (SNAr) reactions on 4,5-dicyano-2-fluoro-1-methylimidazole(2) in dimethyl sulfoxide at room temperature to give secondary amines substituted with dicyanoimidazolyl groups. Aromatic primary diamines and hydrazine similarly react with 2 to give new secondary diamines. Aromatic primary amines substituted with electron withdrawing group such as nitro group and also secondary amines such as carbazole react with 2 only after activation of the amine by deprotonation using sodium hydride. The electrophilicity of 2 is high enough to react with oxyanions such as nitrite and carbonate anions and also polar aprotic solvents via O-attack at 60 °C to give a new imidazolone, 4,5-dicyano-1-methyl-3-(4,5-dicyano-1-methyl-2-imidazolyl)-2-imidazolone(10a). UV-Vis spectra of the newly synthesized compounds are described.
Potassium fluoride activated alcoholysis of hindered siliranes

Abstract The rate of alcoholysis of 1,1-di-t-butylsiliranes is significantly accelerated in the presence of 10% KF and still further enhanced by the addition of 1% 18-crown-6. A pentacoordinate siliconate is proposed as the intermediate responsible for the observed rate increases.
High Genetic Potential for Proteolytic Decomposition in Northern Peatland Ecosystems

ABSTRACT Nitrogen (N) is a scarce nutrient commonly limiting primary productivity. Microbial decomposition of complex carbon (C) into small organic molecules (e.g., free amino acids) has been suggested to supplement biologically fixed N in northern peatlands. We evaluated the microbial (fungal, bacterial, and archaeal) genetic potential for organic N depolymerization in peatlands at Marcell Experimental Forest (MEF) in northern Minnesota. We used guided gene assembly to examine the abundance and diversity of protease genes and further compared them to those of N fixation (nifH) genes in shotgun metagenomic data collected across depths and in two distinct peatland environments (bogs and fens). Microbial protease genes greatly outnumbered nifH genes, with the most abundant genes (archaeal M1 and bacterial trypsin [S01]) each containing more sequences than all sequences attributed to nifH. Bacterial protease gene assemblies were diverse and abundant across depth profiles, indicating a role for bacteria in releasing free amino acids from peptides through depolymerization of older organic material and contrasting with the paradigm of fungal dominance in depolymerization in forest soils. Although protease gene assemblies for fungi were much less abundant overall than those for bacteria, fungi were prevalent in surface samples and therefore may be vital in degrading large soil polymers from fresh plant inputs during the early stage of depolymerization. In total, we demonstrate that depolymerization enzymes from a diverse suite of microorganisms, including understudied bacterial and archaeal lineages, are prevalent within northern peatlands and likely to influence C and N cycling. IMPORTANCE Nitrogen (N) is a common limitation on primary productivity, and its source remains unresolved in northern peatlands that are vulnerable to environmental change. Decomposition of complex organic matter into free amino acids has been proposed as an important N source, but the genetic potential of microorganisms mediating this process has not been examined. Such information can inform possible responses of northern peatlands to environmental change. We show high genetic potential for microbial production of free amino acids across a range of microbial guilds in northern peatlands. In particular, the abundance and diversity of bacterial genes encoding proteolytic activity suggest a predominant role for bacteria in regulating productivity and contrasts with a paradigm of fungal dominance of organic N decomposition. Our results expand our current understanding of coupled carbon and nitrogen cycles in northern peatlands and indicate that understudied bacterial and archaeal lineages may be central in this ecosystem’s response to environmental change.
Synthesis of N-methoxy and N-H aziridines from alkenes

Electron-rich alkenes are converted into N-methoxyaziridines by treatment with HN(OCH3)2 and trimethylsilyl triflate. Reduction with Li/ammonia affords the N-H aziridines.
Highly stereocontrolled and regiocontrolled syntheses of 2,3,4-trisubstituted alkanoates and lactones.

New chlorodiols (±)-3 and (±)-5 are densely functionalized and versatile synthons. They are converted in one step on a gram scale into 2-chlorolactones (±)-6 and (±)-7 and into 4-hydroxy glycidate esters (±)-9 and (±)-10. The 4-hydroxy glycidate esters (±)-9 and (±)-10 are converted stereospecifically and regiospecifically into oxazolines (±)-13 and (±)-14 and into cyclic carbamates (±)-18–(±)-20. The 4-hydroxy glycidate ester (±)-10 undergoes stereocontrolled and regiocontrolled epoxide opening by sodium azide to form the 2-azido-3,4-dihydroxy alkanoate (±)-21. Finally, chlorodiol (±)-5 reacts stereospecifically with silver triflate to form the 2,3-dihydroxyfuranone (±)-26.
RNA-Seq Based Analysis of Population Structure within the Maize Inbred B73

Recent reports have shown than many identically named genetic lines used in research around the world actually contain large amounts of uncharacterized genetic variation as a result of cross contamination of stocks, unintentional crossing, residual heterozygosity within original stocks, or de novo mutation. 27 public, large scale, RNA-seq datasets from 20 independent research groups around the world were used to assess variation within the maize (Zea mays ssp. mays) inbred B73, a four decade old variety which served as the reference genotype for the original maize genome sequencing project and is widely used in genetic, genomic, and phenotypic research. Several clearly distinct clades were identified among putatively B73 samples. A number of these clades were defined by the presence of clearly defined genomic blocks containing a haplotype which did not match the published B73 reference genome. The overall proportion of the maize genotype where multiple distinct haplotypes were observed across different research groups was approximately 2.3%. In some cases the relationship among B73 samples generated by different research groups recapitulated mentor/mentee relationships within the maize genetics community.
Synthesis and characterization of lithium aminoborohydrides: A new class of powerful reducing agents

Abstract Lithium aminoborohydrides (LiABH 3 ), obtained by the reaction of n-BuLi with amine-boranes, are powerful reducing agents, comparable to lithium aluminum hydride, yet selective in their reducing properties. LiABH 3 's reduce esters, lactones, and anhydrides to the corresponding alcohols, while carboxylic acids are not reduced. Test reductions show that LiABH 3 's also reduce a wide range of functional groups, including amides, epoxides, oximes, nitriles, and halides.
Simultaneous Amplification: The Case of Non-interactive Zero-Knowledge

In this work, we explore the question of simultaneous privacy and soundness amplification for non-interactive zero-knowledge argument systems (NIZK). We show that any \(\delta _s-\)sound and \(\delta _z-\)zero-knowledge NIZK candidate satisfying \(\delta _s+\delta _z=1-\epsilon \), for any constant \(\epsilon >0\), can be turned into a computationally sound and zero-knowledge candidate with the only extra assumption of a subexponentially secure public-key encryption.
Does agriculture really matter? the case of Korea, 1910-1970

Este articulo analiza la magnitud del crecimiento en el sector agricola antes de la industrializacion en Korea. Presenta un analisis que es contrario del punto de vista general sobre la naturaleza del crecimiento economico en Korea, cual es el de que este fue muy poco en el sector agricola antes del despegue industrial. Los datos sugieren mas bien, que se realizaron grandes inversiones durante la colonizacion japonesa. Estas inversiones tuvieron altos rendimientos no solo en terminos de produccion de arroz sino tambien en terminos de construccion de capacidad institucional y creacion de infraestructura. El caso koreano no es una anomalia sino un ejemplo algo singular e interesante de desarrollo agricola que antecede a una rapida expansion industrial.
Volcano Video Data Characterized and Classified Using Computer Vision and Machine Learning Algorithms

Abstract Video cameras are common at volcano observatories, but their utility is often limited during periods of crisis due to the large data volume from continuous acquisition and time requirements for manual analysis. For cameras to serve as effective monitoring tools, video frames must be synthesized into relevant time series signals and further analyzed to classify and characterize observable activity. In this study, we use computer vision and machine learning algorithms to identify periods of volcanic activity and quantify plume rise velocities from video observations. Data were collected at Villarrica Volcano, Chile from two visible band cameras located ~17 ​km from the vent that recorded at 0.1 and 30 frames per second between February and April 2015. Over these two months, Villarrica exhibited a diverse range of eruptive activity, including a paroxysmal eruption on 3 March. Prior to and after the eruption, activity included nighttime incandescence, dark and light emissions, inactivity, and periods of cloud cover. We quantify the color and spatial extent of plume emissions using a blob detection algorithm, whose outputs are fed into a trained artificial neural network that categorizes the observable activity into five classes. Activity shifts from primarily nighttime incandescence to ash emissions following the 3 March paroxysm, which likely relates to the reemergence of the buried lava lake. Time periods exhibiting plume emissions are further analyzed using a row and column projection algorithm that identifies plume onsets and calculates apparent plume horizontal and vertical rise velocities. Plume onsets are episodic, occurring with an average period of ~50 ​s and suggests a puffing style of degassing, which is commonly observed at Villarrica. However, the lack of clear acoustic transients in the accompanying infrasound record suggests puffing may be controlled by atmospheric effects rather than a degassing regime at the vent. Methods presented here offer a generalized toolset for volcano monitors to classify and track emission statistics at a variety of volcanoes to better monitor periods of unrest and ultimately forecast major eruptions.
Homological Resonances for Hamiltonian Diffeomorphisms and Reeb Flows

We show that whenever a Hamiltonian diffeomorphism or a Reeb flow has a finite number of periodic orbits, the mean indices of these orbits must satisfy a resonance relation, provided that the ambient manifold meets some natural requirements. In the case of Reeb flows, this leads to simple expressions (purely in terms of the mean indices) for the mean Euler characteristics. These are invariants of the underlying contact structure which are capable of distinguishing some contact structures that are homotopic but not diffeomorphic.
Limit theorems of a 3-state quantum walk and its application for discrete uniform measures

We present two long-time limit theorems of a 3-state quantum walk on the line when the walker starts from the origin. One is a limit measure which is obtained from the probability distribution of the walk at a long-time limit, and the other is a convergence in distribution for the walker's position in a rescaled space by time. In addition, as an application of the walk, we obtain discrete uniform limit measures from the 3-state walk with a delocalized initial state.
Scott sentences for certain groups

We give Scott sentences for certain computable groups, and we use index set calculations as a way of checking that our Scott sentences are as simple as possible. We consider finitely generated groups and torsion-free abelian groups of finite rank. For both kinds of groups, the computable ones all have computable $$\varSigma _3$$ Scott sentences. Sometimes we can do better. In fact, the computable finitely generated groups that we have studied all have Scott sentences that are “computable d- $$\varSigma _2$$ ” (the conjunction of a computable $$\varSigma _2$$ sentence and a computable $$\varPi _2$$ sentence). In [9], this was shown for the finitely generated free groups. Here we show it for all finitely generated abelian groups, and for the infinite dihedral group. Among the computable torsion-free abelian groups of finite rank, we focus on those of rank 1. These are exactly the additive subgroups of $$\mathbb {Q}$$ . We show that for some of these groups, the computable $$\varSigma _3$$ Scott sentence is best possible, while for others, there is a computable d- $$\varSigma _2$$ Scott sentence.
On arboreal Galois representations of rational functions

The action of the absolute Galois group Gal(Ksep/K)Gal(Ksep/K) of a global field K on a tree T(ϕ,α)T(ϕ,α) of iterated preimages of α∈P1(K)α∈P1(K) under ϕ∈K(x)ϕ∈K(x) with deg⁡(ϕ)≥2deg⁡(ϕ)≥2 induces a homomorphism ρ:Gal(Ksep/K)→Aut(T(ϕ,α))ρ:Gal(Ksep/K)→Aut(T(ϕ,α)), which is called an arboreal Galois representation. In this paper, we address a number of questions posed by Jones and Manes [5] ; [6] about the size of the group G(ϕ,α):=imρ=lim←n⁡Gal(K(ϕ−n(α))/K). Specifically, we consider two cases for the pair (ϕ,α)(ϕ,α): (1) ϕ is such that the sequence {an}{an} defined by a0=αa0=α and an=ϕ(an−1)an=ϕ(an−1) is periodic, and (2) ϕ commutes with a nontrivial Mobius transformation that fixes α. In the first case, we resolve a question posed by Jones [5] about the size of G(ϕ,α)G(ϕ,α), and taking K=QK=Q, we describe the Galois groups of iterates of polynomials ϕ∈Z[x]ϕ∈Z[x] that have the form ϕ(x)=x2+kxϕ(x)=x2+kx or ϕ(x)=x2−(k+1)x+kϕ(x)=x2−(k+1)x+k. When K=QK=Q and ϕ∈Z[x]ϕ∈Z[x], arboreal Galois representations are a useful tool for studying the arithmetic dynamics of ϕ . In the case of ϕ(x)=x2+kxϕ(x)=x2+kx for k∈Zk∈Z, we employ a result of Jones [4] regarding the size of the group G(ψ,0)G(ψ,0), where ψ(x)=x2−kx+kψ(x)=x2−kx+k, to obtain a zero-density result for primes dividing terms of the sequence {an}{an} defined by a0∈Za0∈Z and an=ϕ(an−1)an=ϕ(an−1). In the second case, we resolve a conjecture of Jones [5] about the size of a certain subgroup C(ϕ,α)⊂Aut(T(ϕ,α))C(ϕ,α)⊂Aut(T(ϕ,α)) that contains G(ϕ,α)G(ϕ,α), and we present progress toward the proof of a conjecture of Jones and Manes [6] concerning the size of G(ϕ,α)G(ϕ,α) as a subgroup of C(ϕ,α)C(ϕ,α).
Convergent deduction for probabilistic logic

This paper discusses the semantics and proof theory of Nilsson's probabilistic logic, outlining both the benefits of its well-defined model theory and the drawbacks of its proof theory. Within Nilsson's semantic framework, we derive a set of inference rules which are provably sound. The resulting proof system, in contrast to Nilsson's approach, has the important feature of convergence - that is, the inference process proceeds by computing increasingly narrow probability intervals which converge from above and below on the smallest entailed probability interval. Thus the procedure can be stopped at any time to yield partial information concerning the smallest entailed interval.
Unobservable False Data Injection Attacks against PMUs: Feasible Conditions and Multiplicative Attacks

This paper studies false data injection (FDI) attacks against phasor measurement units (PMUs). As compared to the conventional bad data detector (BDD), an enhanced BDD utilizing the effect of zero injection buses is proposed. Feasible conditions under which FDI attacks are unobservable to this enhanced BDD are discussed. In addition, a class of multiplicative FDI attacks that maintain the rank of the PMU measurement matrix is introduced. Simulation results on the IEEE RTS-24-bus system indicate that the these multiplicative unobservable attacks can avoid detection by both the enhanced BDD and a detector based on low-rank decomposition proposed in prior work.
Decomposition of random graphs into complete bipartite graphs

We consider the problem of partitioning the edge set of a graph $G$ into the minimum number $\tau(G)$ of edge-disjoint complete bipartite subgraphs. We show that for a random graph $G$ in $G(n,p)$, where $p$ is a constant no greater than $1/2$, asymptotically almost surely $\tau(G)$ is between $n- c(\log_{1/p} n)^{3+\epsilon}$ and $n - (2+o(1))\log_{1/(1-p)} n$ for any positive constants $c$ and $\epsilon$.
Neural Rejuvenation: Improving Deep Network Training by Enhancing Computational Resource Utilization

In this paper, we study the problem of improving computational resource utilization of neural networks. Deep neural networks are usually over-parameterized for their tasks in order to achieve good performances, thus are likely to have underutilized computational resources. This observation motivates a lot of research topics, e.g. network pruning, architecture search, etc. As models with higher computational costs (e.g. more parameters or more computations) usually have better performances, we study the problem of improving the resource utilization of neural networks so that their potentials can be further realized. To this end, we propose a novel optimization method named Neural Rejuvenation. As its name suggests, our method detects dead neurons and computes resource utilization in real time, rejuvenates dead neurons by resource reallocation and reinitialization, and trains them with new training schemes. By simply replacing standard optimizers with Neural Rejuvenation, we are able to improve the performances of neural networks by a very large margin while using similar training efforts and maintaining their original resource usages. The code is available here: https://github.com/joe-siyuan-qiao/NeuralRejuvenation-CVPR19
Class Groups and Selmer Groups

Abstract It is often the case that a Selmer group of an abelian variety and a group related to an ideal class group can both be naturally embedded into the same cohomology group. One hopes to compute one from the other by finding how close each is to their intersection. In this paper we compute the two groups and their intersection explicitly in the local case and put together the local information to get sharp upper bounds in the global case. The techniques in this paper can be used for arbitrary abelian varieties, isogenies and number fields assuming a frequently occurring condition. Several examples are worked out for the Jacobians of elliptic and hyperelliptic curves.
Centralized Repair of Multiple Node Failures With Applications to Communication Efficient Secret Sharing

This paper considers a distributed storage system, where multiple storage nodes can be reconstructed simultaneously at a centralized location. This centralized multi-node repair (CMR) model is a generalization of regenerating codes that allow for bandwidth efficient repair of a single-failed node. This paper focuses on the tradeoff between the amount of data stored and repair bandwidth in the CMR model. In particular, repair bandwidth bounds are derived for the minimum storage multi-node repair (MSMR) and the minimum bandwidth multi-node repair (MBMR) operating points. The tightness of these bounds is analyzed via code constructions. The MSMR point is characterized by codes achieving this point under functional repair for the general set of CMR parameters, as well as with codes enabling exact repair for certain CMR parameters. The MBMR point, on the other hand, is characterized with exact repair codes for all CMR parameters for systems that satisfy a certain entropy accumulation property. Finally, the model proposed here is utilized for the secret sharing problem, where the codes for the multi-node repair problem are used to construct communication efficient secret sharing schemes with the property of bandwidth efficient share repair.
Betweenness centrality profiles in trees

Betweenness centrality of a vertex in a graph measures the fraction of shortest paths going through the vertex. This is a basic notion for determining the importance of a vertex in a network. The k-betweenness centrality of a vertex is defined similarly, but only considers shortest paths of length at most k. The sequence of k-betweenness centralities for all possible values of k forms the betweenness centrality profile of a vertex. We study properties of betweenness centrality profiles in trees. We show that for scale-free random trees, for fixed k, the expectation of k-betweenness centrality strictly decreases as the index of the vertex increases. We also analyze worst-case properties of profiles in terms of the distance of profiles from being monotone, and the number of times pairs of profiles can cross. This is related to whether k-betweenness centrality, for small values of k, may be used instead of having to consider all shortest paths. Bounds are given that are optimal in order of magnitude. We also present some experimental results for scale-free random trees.
SVD-PHAT: A Fast Sound Source Localization Method

This paper introduces a new localization method called SVD-PHAT. The SVD-PHAT method relies on Singular Value De-composition of the SRP-PHAT projection matrix. A k-d tree is also proposed to speed up the search for the most likely direction of arrival of sound. We show that this method per-forms as accurately as SRP-PHAT, while reducing significantly the amount of computation required.
Minkowski’s theorem on independent conjugate units

We call a unit \(\beta \) in a finite Galois extension \(l/\mathbb {Q}\) a Minkowski unit if the subgroup generated by \(\beta \) and its conjugates over \(\mathbb {Q}\) has maximum rank in the unit group of l. Minkowski showed the existence of such units in every Galois extension. We give a new proof of Minkowski’s theorem and show that there exists a Minkowski unit \(\beta \in l\) such that the Weil height of \(\beta \) is comparable with the sum of the heights of a fundamental system of units for l. Our proof implies a bound on the index of the subgroup generated by the algebraic conjugates of \(\beta \) in the unit group of l. If k is an intermediate field such that \(\mathbb {Q}\subseteq k \subseteq l\), and \(l/\mathbb {Q}\) and \(k/\mathbb {Q}\) are Galois extensions, we prove an analogous bound for the subgroup of relative units. In order to establish our results for relative units, a number of new ideas are combined with techniques from the geometry of numbers and the Galois action on places.
A Monte Carlo Radiation Transfer Study of Photospheric Emission in Gamma-Ray Bursts

We present the analysis of photospheric emission for a set of hydrodynamic simulations of long duration gamma-ray burst jets from massive compact stars. The results are obtained by using the Monte Carlo Radiation Transfer code (MCRaT) to simulate thermal photons scattering through the collimated outflows. MCRaT allows us to study explicitly the time evolution of the photosphere within the photospheric region, as well as the gradual decoupling of the photon and matter counterparts of the jet. The results of the radiation transfer simulations are also used to construct light curves and time-resolved spectra at various viewing angles, which are then used to make comparisons with observed data and outline the agreement and strain points between the photospheric model and long duration gamma-ray burst observations. We find that our fitted time-resolved spectral Band β parameters are in agreement with observations, even though we do not consider the effects of nonthermal particles. Finally, the results are found to be consistent with the Yonetoku correlation, but bear some strain with the Amati correlation.
On the 1/3–2/3 Conjecture

Let (P, ≤) be a finite poset (partially ordered set), where P has cardinality n. Consider linear extensions of P as permutations x1x2⋯xn in one-line notation. For distinct elements x, y ∈ P, we define ℙ(x ≺ y) to be the proportion of linear extensions of P in which x comes before y. For $0\leq \alpha \leq \frac {1}{2}$ , we say (x, y) is an α-balanced pair if α ≤ ℙ(x ≺ y) ≤ 1 − α. The 1/3–2/3 Conjecture states that every finite partially ordered set which is not a chain has a 1/3-balanced pair. We make progress on this conjecture by showing that it holds for certain families of posets. These include lattices such as the Boolean, set partition, and subspace lattices; partial orders that arise from a Young diagram; and some partial orders of dimension 2. We also consider various posets which satisfy the stronger condition of having a 1/2-balanced pair. For example, this happens when the poset has an automorphism with a cycle of length 2. Various questions for future research are posed.
Stress concentrations and bone microdamage: John Currey's contributions to understanding the initiation and arrest of cracks in bone.

Abstract The microarchitecture of bone tissue presents many features that could act as stress concentrators for the initiation of bone microdamage. This was first identified by John Currey in a seminal paper in 1962 in which he presented the mechanical and biological evidence for stress concentrations at the bone surface, within the bone through the action of stiffness differentials between architectural features including between lamellae, and at the level of the lacunar and canalicular walls. Those early observations set the stage to consider how microscopic damage to bone tissue might affect the properties of bone at a time when most in the scientific community dismissed microcracks in bone as artifact. Evidence collected in the nearly 60 years since those important initial observations suggest that some of these architectural features in bone tissue are more effective as crack arrestors than as crack initiators. Sites of higher mineralization in the bone matrix, particularly interstitial sites in both cortical and trabecular bone, may serve preferentially as locations for crack initiation, whereas those boundaries identified by Currey as both stress concentrators and stress arrestors are more effective at stopping cracks than at initiating them.
Inference With Dyadic Data: Asymptotic Behavior of the Dyadic-Robust t-Statistic

ABSTRACTThis article is concerned with inference in the linear model with dyadic data. Dyadic data are indexed by pairs of “units;” for example, trade data between pairs of countries. Because of th...
Transitivity degrees of countable groups and acylindrical hyperbolicity

We prove that every countable acylindrically hyperbolic group admits a highly transitive action with finite kernel. This theorem uniformly generalizes many previously known results and allows us to answer a question of Garion and Glassner on the existence of highly transitive faithful actions of mapping class groups. It also implies that in various geometric and algebraic settings, the transitivity degree of an infinite group can only take two values, namely 1 and ∞. Here, by transitivity degree of a group we mean the supremum of transitivity degrees of its faithful permutation representations. Further, for any countable group G admitting a highly transitive faithful action, we prove the following dichotomy: Either G contains a normal subgroup isomorphic to the infinite alternating group or G resembles a free product from the model theoretic point of view. We apply this theorem to obtain new results about universal theory and mixed identities of acylindrically hyperbolic groups. Finally, we discuss some open problems.
Smooth Compactness for Spaces of Asymptotically Conical Self-Expanders of Mean Curvature Flow

We show compactness in the locally smooth topology for certain natural families of asymptotically conical self-expanding solutions of mean curvature flow. Specifically, we show such compactness for the set of all two-dimensional self-expanders of a fixed topological type and, in all dimensions, for the set of self-expanders of low entropy and for the set of mean convex self-expanders with strictly mean convex asymptotic cones. From this we deduce that the natural projection map from the space of parameterizations of asymptotically conical self-expanders to the space of parameterizations of the asymptotic cones is proper for these classes.
Stochastic Smoothing for Nonsmooth Minimizations: Accelerating SGD by Exploiting Structure

In this work we consider the stochastic minimization of nonsmooth convex loss functions, a central problem in machine learning. We propose a novel algorithm called Accelerated Nonsmooth Stochastic Gradient Descent (ANSGD), which exploits the structure of common nonsmooth loss functions to achieve optimal convergence rates for a class of problems including SVMs. It is the first stochastic algorithm that can achieve the optimal O(1/t) rate for minimizing nonsmooth loss functions (with strong convexity). The fast rates are confirmed by empirical comparisons, in which ANSGD significantly outperforms previous subgradient descent algorithms including SGD.
The Seiberg–Witten equations on manifolds with boundary I: the space of monopoles and their boundary values

In this paper, we study the Seiberg-Witten equations on a compact 3-manifold with boundary. Solutions to these equations are called monopoles. Under some simple topological assumptions, we show that the solution space of all monopoles is a Banach manifold in suitable function space topologies. We then prove that the restriction of the space of monopoles to the boundary is a submersion onto a Lagrangian submanifold of the space of connections and spinors on the boundary. Both these spaces are infinite dimensional, even modulo gauge, since no boundary conditions are specified for the Seiberg-Witten equations on the 3-manifold. We study the analytic properties of these monopole spaces with an eye towards developing a monopole Floer theory for 3-manifolds with boundary, which we pursue in Part II.
Generating Infinite Random Graphs

We define a growing model of random graphs. Given a sequence of non-negative integers {dn}n=0∞ with the property that di≤i, we construct a random graph on countably infinitely many vertices v0, v1… by the following process: vertex vi is connected to a subset of {v0, …, vi−1} of cardinality di chosen uniformly at random. We study the resulting probability space. In particular, we give a new characterization of random graphs, and we also give probabilistic methods for constructing infinite random trees.
Frames induced by the action of continuous powers of an operator

Abstract We investigate systems of the form { A t g : g ∈ G , t ∈ [ 0 , L ] } where A ∈ B ( H ) is a normal operator in a separable Hilbert space H , G ⊂ H is a countable set, and L is a positive real number. Although the main goal of this work is to study the frame properties of { A t g : g ∈ G , t ∈ [ 0 , L ] } , as intermediate steps, we explore the completeness and Bessel properties of such systems from a theoretical perspective, which are of interest by themselves. Beside the theoretical appeal of investigating such systems, their connections to dynamical and mobile sampling make them fundamental for understanding and solving several major problems in engineering and science.
How Many Units Can a Commutative Ring Have

AbstractLaszlo Fuchs posed the following problem in 1960, which remains open: determine whether a given abelian group can occur as the group of units in a commutative ring. In this note, we provide...
Understanding the Correlation Gap for Matchings

Given a set of vertices $V$ with $|V| = n$, a weight vector $w \in (\mathbb{R}^+ \cup \{ 0 \})^{\binom{V}{2}}$, and a probability vector $x \in [0, 1]^{\binom{V}{2}}$ in the matching polytope, we study the quantity $\frac{E_{G}[ \nu_w(G)]}{\sum_{(u, v) \in \binom{V}{2}} w_{u, v} x_{u, v}}$ where $G$ is a random graph where each edge $e$ with weight $w_e$ appears with probability $x_e$ independently, and let $\nu_w(G)$ denotes the weight of the maximum matching of $G$. This quantity is closely related to correlation gap and contention resolution schemes, which are important tools in the design of approximation algorithms, algorithmic game theory, and stochastic optimization. We provide lower bounds for the above quantity for general and bipartite graphs, and for weighted and unweighted settings. he best known upper bound is $0.54$ by Karp and Sipser, and the best lower bound is $0.4$. We show that it is at least $0.47$ for unweighted bipartite graphs, at least $0.45$ for weighted bipartite graphs, and at lea st $0.43$ for weighted general graphs. To achieve our results, we construct local distribution schemes on the dual which may be of independent interest.
Cyclically presented groups with length four positive relators

For cyclically presented groups $G = G_n(w)$ with positive length four relators $w = x_0x_jx_kx_l$ in the free group with basis $x_0, x_1, \ldots, x_{n-1}$, we classify finiteness and, modulo two unresolved cases, we classify asphericity for the underlying presentations. We show that the fixed point subgroup of the shift $x_i \mapsto x_{i+1}$ is always finite and we relate finiteness of $G$ and asphericity to the dynamics of the shift action by the cyclic group of order $n$ on the nonidentity elements of $G$.