cssi/SciSciGPT-SciSciNet huggingface dataset:
Application of Plasma FIB to Analyze a Single Oxide Inclusion in Steel

We demonstrate that Plasma Dual Beam focused ion beam (PFIB) milling can be used for high-resolution three-dimensional chemical study of a single non-metallic inclusion in steel. A CaO-Al2O3-MgO inclusion (~ 10 μm) on a polished cross-section of steel sample was located and milled using a Xe+ ion beam. A secondary electron image and EDS map of every section were recorded and subsequently processed to show the 3D chemistry and morphology of the inclusion.
Pseudorandomness from Shrinkage

One powerful theme in complexity theory and pseudorandomness in the past few decades has been the use of lower bounds to give pseudorandom generators (PRGs). However, the general results using this hardness vs. randomness paradigm suffer from a quantitative loss in parameters, and hence do not give nontrivial implications for models where we don’t know super-polynomial lower bounds but do know lower bounds of a fixed polynomial. We show that when such lower bounds are proved using random restrictions, we can construct PRGs which are essentially best possible without in turn improving the lower bounds. More specifically, say that a circuit family has shrinkage exponent Γ if a random restriction leaving a p fraction of variables unset shrinks the size of any circuit in the family by a factor of pΓ + o(1). Our PRG uses a seed of length s1/(Γ + 1) + o(1) to fool circuits in the family of size s. By using this generic construction, we get PRGs with polynomially small error for the following classes of circuits of size s and with the following seed lengths: (1) For de Morgan formulas, seed length s1/3+o(1); (2) For formulas over an arbitrary basis, seed length s1/2+o(1); (3) For read-once de Morgan formulas, seed length s.234...; (4) For branching programs of size s, seed length s1/2+o(1). The previous best PRGs known for these classes used seeds of length bigger than n/2 to output n bits, and worked only for size s=O(n) [8].
FireSim: FPGA-Accelerated Cycle-Exact Scale-Out System Simulation in the Public Cloud

In this article, we present FireSim, an open-source simulation platform that enables fast cycle-exact microarchitectural simulation of large scale-out clusters by combining FPGA-accelerated simulation of silicon-proven RTL designs with scalable, distributed network simulation, running on a public-cloud host platform. By introducing automation and harnessing cloud FPGAs, FireSim provides the usability and productivity of software full-system simulators with the high performance and accuracy of FPGA-accelerated simulation, while adding the unprecedented ability to scale to globally cycle-accurate simulations of thousands of networked nodes. To demonstrate FireSim's scalability, we automatically generate and deploy a target cluster simulation of 1024 3.2-GHz quad-core server nodes, each with 16 GB of DRAM, interconnected by a 200 Gb/s network with low latency, which simulates at a 6.6-MHz processor clock rate ($< $<500× slowdown over real time). In aggregate, this simulation harnesses millions of dollars of FPGAs—at a cost of only hundreds of dollars per simulation-hour to users.
Understanding the Social Science Effect: An Intervention in Life Course Generosity:

Does interacting with social science data in early adulthood promote generosity? To investigate this question from a life course development perspective, two distinct samples were drawn for a surve...
Productivity Growth : Patterns and Determinants across the World

This is the background paper for the productivity extension of the World Bank’s Long-Term Growth Model (LTGM). Based on an extensive literature review, the paper identifies the main determinants of economic productivity as innovation, education, market efficiency, infrastructure, and institutions. Based on underlying proxies, the paper constructs indexes representing each of the main categories of productivity determinants and, combining them through principal component analysis, obtains an overall determinant index. This is done for every year in the three decades spanning 1985–2015 and for more than 100 countries. In parallel, the paper presents a measure of total factor productivity (TFP), largely obtained from the Penn World Table, and assesses the pattern of productivity growth across regions and income groups over the same sample. The paper then examines the relationship between the measures of TFP and its determinants. The variance of productivity growth is decomposed into the share explained by each of its main determinants, and the relationship between productivity growth and the overall determinant index is identified. The variance decomposition results show that the highest contributor among the determinants to the variance in TFP growth is market efficiency for Organisation for Economic Co-operation and Development countries and education for developing countries in the most recent decade. The regression results indicate that, controlling for country- and time-specific effects, TFP growth has a positive and significant relationship with the proposed TFP determinant index and a negative relationship with initial TFP. This relationship is then used to provide a set of simulations on the potential path of TFP growth if certain improvements on TFP determinants are achieved. The paper presents and discusses some of these simulations for groups of countries by geographic region and income level. An accompanying Excel-based toolkit, linked to the LTGM, provides a larger set of simulations and scenario analysis at the country level for the next few decades.
Preparation of N,N,N′,N′-2,3-Hexamethyl-2,3-butanediamine

Abstract The title compound has been prepared by aminolysis (dimethylamine) of the corresponding hexamethyl aziridinium iodide.
Evolutionary design of regulatory control. II. Robust error-correcting feedback increases genetic and phenotypic variability

Abstract As systems become more robust against perturbations, they can compensate for greater sloppiness in the performance of their components. That robust compensation reduces the force of natural selection on the system’s components, leading to component decay. The paradoxical coupling of robustness and decay predicts that robust systems evolve cheaper, lower performing components, which accumulate greater mutational genetic variability and which have greater phenotypic stochasticity in trait expression. Previous work noted the paradox of robustness. However, no general theory for the evolutionary dynamics of system robustness and component decay has been developed. This article takes a first step by linking engineering control theory with the genetic theory of evolutionary dynamics. Control theory emphasizes error-correcting feedback as the single greatest principle in robust system design. Linking control theory to evolution leads to a theory for the evolutionary dynamics of error-correcting feedback, a unifying approach for the evolutionary analysis of robust systems. This article shows how increasingly robust systems accumulate more genetic variability and greater stochasticity of expression in their components. The theory predicts different levels of variability between different regulatory control architectures and different levels of variability between different components within a particular regulatory control system. The theory also shows that increasing robustness reduces the frequency of system failures associated with disease and, simultaneously, causes a strong increase in the heritability of disease. Thus, robust error correction in biological regulatory control may partly explain the puzzlingly high heritability of disease and, more generally, the surprisingly high heritability of fitness.
The use of boron clusters in the rational design of boronated nucleosides for neutron capture therapy of cancer

Abstract Boron neutron capture therapy (BNCT) is a chemoradio–therapeutic method for the treatment of cancer. It depends on the selective targeting of tumor cells by boron-containing compounds. One category of BNCT agents that has received extensive attention during recent years is boronated nucleosides. Such structures may be converted to the corresponding 5′-monophosphates by phosphorylating enzymes and thereby entrapped in tumor cells by the virtue of the acquired negative charge. This review analyzes previous design strategies applied in the synthesis of boron cluster-containing nucleosides and discusses possible future developments in this field based on existing knowledge of enzyme tissue expressions, enzyme substrate specificities, and contemporary trends in rational drug design.
The Evolution of Surface Chemistry. A Personal View of Building the Future on Past and Present Accomplishments

Surface chemistry, like other branches of physical chemistry, historically developed through macrosopic studies. These included measurements of adsorption−desorption equilibria (adsorption isotherms), spreading of monomolecular films, surface dissociation of diatomic molecules, and kinetic studies of desorption, sticking, and catalytic oxidation of CO and H2. Models of surface structures were proposed by Langmuir and Taylor on the bases of experimental findings. Molecular level studies of surface chemistry were delayed as compared to other fields of physical chemistry until the late 1950s as instrumentation to detect properties of the very small number of surface atoms (1015 cm-2) in the presence of a large number of bulk atoms (1022 cm-3) were not available. At present we have over 65 techniques (photon, electron, molecule, and ion scattering, and scanning probes) that can investigate composition, atomic and electronic structures, and the dynamics of their motion with ≤1% of a monolayer sensitivity. Key ...
Enantioselective routes to chiral benzylic thiols, sulfinic esters and sulfonic acids illustrated by the 1-phenylethyl series

Abstract Chiral benzylic thiols, sulfinic esters and sulfonic acids can be produced readily and in excellent enantiomeric purity from the corresponding achiral ketones.
Preparation and Catalytic Properties of Immobilized Chiral Dirhodium(II) Carboxamidates

Chiral dirhodium(II) tetrakis[methyl 2-oxypyrrolidine-5(S)-carboxylate] has been immobilized on polystyrene−poly(ethylene glycol) and Merrifield resins. Intra- and intermolecular cyclopropanation r...
The OsO4F-, OsO4F22-, and OsO3F3- Anions, Their Study by Vibrational and NMR Spectroscopy and Density Functional Theory Calculations, and the X-ray Crystal Structures of [N(CH3)4][OsO4F] and [N(CH3)4][OsO3F3]

The fluoride ion acceptor properties of OsO4 and OsO3F2 were investigated. The salts [N(CH3)4][OsO4F] and [N(CH3)4]2[OsO4F2] were prepared by the reactions of OsO4 with stoichiometric amounts of [N(CH3)4][F] in CH3CN solvent. The salts [N(CH3)4][OsO3F3] and [NO][OsO3F3] were prepared by the reactions of OsO3F2 with a stoichiometric amount of [N(CH3)4][F] in CH3CN solvent and with excess NOF, respectively. The OsO4F- anion was fully structurally characterized in the solid state by vibrational spectroscopy and by a single-crystal X-ray diffraction study of [N(CH3)4][OsO4F]: Abm2, a = 7.017(1) A, b = 11.401(2) A, c = 10.925(2) A, V = 874.1(3) A3, Z = 4, and R = 0.0282 at −50 °C. The cis-OsO4F22- anion was characterized in the solid state by vibrational spectroscopy, and previous claims regarding the cis-OsO4F22- anion are shown to be erroneous. The fac-OsO3F3- anion was fully structurally characterized in CH3CN solution by 19F NMR spectroscopy and in the solid state by vibrational spectroscopy of its N(CH3)...
Catalytic reduction of nitric oxide on PdO—MoO3/γ-Al2O3

Abstract The activity and selectivity of PdO—MoO 3 /γ-Al 2 O 3 catalysts containing 2% Pd and 20% Mo for the reduction of nitric oxide by carbon monoxide, by hydrogen, and by a mixture of CO + H 2 was investigated in the presence of different amounts of oxygen at reaction temperatures from 25 to 550°C. Results are compared with PdO/γ-Al 2 O 3 , MoO 3 /γ-Al 2 O 3 , and a commercial Pt—Rh catalyst. The palladium determines the performance of PdO—MoO 3 /γ-Al 2 O 3 under oxygen free reaction conditions up to 400°C, notwithstanding the high loading of the molybdena. At higher temperatures the molybdena can improve the performance of the catalyst, especially at slightly oxidizing conditions. Neither the activity nor the selectivity of PdO—MoO 3 /γ-Al 2 O 3 resemble those of the monometallic catalysts in the presence of oxygen when CO + H 2 is used for reduction. In the case of the present catalyst in fresh condition, nitric oxide is reduced selectively to nitrogen and nitrous oxide with a conversion > 70% at temperatures from 300 to 550°C under either slightly reducing or slightly oxidizing conditions.
Engineering of Primary Human B cells with CRISPR/Cas9 Targeted Nuclease.

B cells offer unique opportunities for gene therapy because of their ability to secrete large amounts of protein in the form of antibody and persist for the life of the organism as plasma cells. Here, we report optimized CRISPR/Cas9 based genome engineering of primary human B cells. Our procedure involves enrichment of CD19+ B cells from PBMCs followed by activation, expansion, and electroporation of CRISPR/Cas9 reagents. We are able expand total B cells in culture 10-fold and outgrow the IgD+ IgM+ CD27− naive subset from 35% to over 80% of the culture. B cells are receptive to nucleic acid delivery via electroporation 3 days after stimulation, peaking at Day 7 post stimulation. We tested chemically modified sgRNAs and Alt-R gRNAs targeting CD19 with Cas9 mRNA or Cas9 protein. Using this system, we achieved genetic and protein knockout of CD19 at rates over 70%. Finally, we tested sgRNAs targeting the AAVS1 safe harbor site using Cas9 protein in combination with AAV6 to deliver donor template encoding a splice acceptor-EGFP cassette, which yielded site-specific integration frequencies up to 25%. The development of methods for genetically engineered B cells opens the door to a myriad of applications in basic research, antibody production, and cellular therapeutics.
Enantioselective Total Synthesis of Nicandrenones

d p-TsOH, MeOH, 23 °C. e LDA, TMSCl, -78 °C. f Pd(OAc)2 ,O 2, DMSO, 23 °C. g L-selectride, THF, -78 °C. h t-BuOOH, VO(acac)2 ,C H 2Cl2 ,0 °C. i Ac2O, Et3N, DMAP, -25 °C. n K 2CO3, MeOH, 23 °C. o MgI2, NaI, CH2Cl2-CH3CN, 0 °C. p CH3SO2Cl, Et3N,
Synthesis, Crystal Structure, and Properties of HfM′P (M′ = Fe, Co, Ni) in comparison to ZrNiP

The new phosphides HfM′P (M′ = Fe, Co, Ni) have been synthesized by arc melting of HfP and the corresponding 3 d metal, and subsequent annealing at 1400°C. The lattice constants vary from a = 6.247(2) A, b = 3.7177(6) A, c = 7.137(2) A, V = 165.74(8) A3 for HfFeP, a = 6.295(3) A, b = 3.668(2) A, c = 7.175(4) A, V = 165.7(2) A3 for HfCoP to a = 6.240(3) A, b = 3.716(2) A, c = 7.135(2) A, V = 165.4(2) A3 (HfNiP) in the orthorhombic space group Pnma. Although ZrNiP occurs only in the Ni2In structure type, all three Hf phosphides crystallize in the Co2Si structure type, isotypic to ZrFeP and ZrCoP. The structural differences between HfNiP and ZrNiP can be explained by the preference of Hf for structures with more metal-metal bonds rather than by size effects. Synthese, Kristallstruktur und Eigenschaften von HfM′P (M′ = Fe, Co, Ni) im Vergleich mit ZrNiP Die neuen Phosphide HfM′P (M′ = Fe, Co, Ni) wurden durch Aufschmelzen von HfP und dem entsprechenden 3 d Metall im Lichtbogen und anschliesendem Tempern bei 1400°C hergestellt. Die Zellkonstanten variieren von a = 6.247(2) A, b = 3.7177(6) A, c = 7.137(2) A, V = 165.74(8) A3 fur HfFeP, a = 6.295(3) A, b = 3.668(2) A, c = 7.175(4) A, V = 165.7(2) A3 fur HfCoP bis a = 6.240(3) A, b = 3.716(2) A, c = 7.135(2) A, V = 165.4(2) A3 (HfNiP) in der orthorhombischen Raumgruppe Pnma. Obwohl ZrNiP nur im Ni2In-Strukturtyp auftritt, kristallisieren alle drei Hafniumphosphide im Co2Si-Strukturtyp, isotyp zu ZrFeP und ZrCoP. Die strukturellen Unterschiede zwischen HfNiP und ZrNiP lassen sich eher auf die Vorliebe des Hf fur Strukturen mit mehr Metall-Metall-Bindungen zuruckfuhren, als auf die unterschiedlichen Radien von Zr und Hf.
A Stereocontrolled, Convergent Synthesis of Hydroxyethylene Dipeptide Isosteres

A simple, convergent, and stereoselective synthesis of hydroxyethylene dipeptide isosteres 1 and 2 from scalemic α-hydroxy esters has been developed. The method is short (six steps), efficient (≈15...
Combining multiple functional annotation tools increases coverage of metabolic annotation

Genome-scale metabolic modeling is a cornerstone of systems biology analysis of microbial organisms and communities, yet these genome-scale modeling efforts are invariably based on incomplete functional annotations. Annotated genomes typically contain 30–50% of genes without functional annotation, severely limiting our knowledge of the “parts lists” that the organisms have at their disposal. These incomplete annotations may be sufficient to derive a model of a core set of well-studied metabolic pathways that support growth in pure culture. However, pathways important for growth on unusual metabolites exchanged in complex microbial communities are often less understood, resulting in missing functional annotations in newly sequenced genomes. Here, we present results on a comprehensive reannotation of 27 bacterial reference genomes, focusing on enzymes with EC numbers annotated by KEGG, RAST, EFICAz, and the BRENDA enzyme database, and on membrane transport annotations by TransportDB, KEGG and RAST. Our analysis shows that annotation using multiple tools can result in a drastically larger metabolic network reconstruction, adding on average 40% more EC numbers, 3–8 times more substrate-specific transporters, and 37% more metabolic genes. These results are even more pronounced for bacterial species that are phylogenetically distant from well-studied model organisms such as E. coli. Metabolic annotations are often incomplete and inconsistent. Combining multiple functional annotation tools can greatly improve genome coverage and metabolic network size, especially for non-model organisms and non-core pathways.
Crystal growth of incommensurate members of 2H-hexagonal perovskite related oxides: Ba4MzPt3−zO9 (M=Co, Ni, Cu, Zn, Mg, Pt)

Abstract Millimeter sized crystals of six oxides of approximate composition Ba4MzPt3-zO9 (M=Co, Ni, Cu, Zn, Mg, Pt) were grown from molten K2CO3 fluxes and found to crystallize in a 2H hexagonal perovskite-related structure type. The compositions of these incommensurate structures, which belong to the A3n+3mA′nB3m+nO9m+6n family of 2H hexagonal perovskite related oxides, were characterized by X-ray diffraction, energy dispersive spectroscopy, and magnetic susceptibility measurements. The specific synthetic considerations, crystal growth conditions, and magnetic susceptibility measurements are discussed.
Trends in stability for N18 cages

Nitrogen molecules Nx have been extensively studied for their potential as high energy density materials (HEDM). Cages of three-coordinate nitrogen have been studied to determine the structural features that result in the most stable isomers. N12 cages, for example, have been shown to follow a general trend that molecules with more pentagons in the network are more stable than other molecules. Larger Nx cages (24 or more atoms) do not follow this trend, favoring cylindrical structures over spherical ones with larger numbers of pentagons. To determine which trends intermediate-sized Nx cages follow, a series of N18 cages are studied by theoretical calculations of their stability. Geometries are optimized by using Hartree−Fock theory and perturbation theory (MP3), with single energies calculated with the fourth-order perturbation theory (MP4). The correlation-consistent CC-PVDZ basis of Dunning is employed. The major result is a loose trend favoring pentagons, with the most stable molecules being the ones w...
BENZOCYCLOBUTADIENES VIA ELECTROCYCLIZATIONS OF (Z,Z)-3,5-OCTADIENE-1,7-DIYNES LEADING TO DIMERS WITH UNUSUAL POLYCYCLIC STRUCTURES

(Z,Z)-3,5-Octadiene-1,7-diynes 15a−e were synthesized by condensation of enynyl aldehydes 12a−e with allenylborane 11 to furnish enynyl alcohols 14a−e followed by the elimination step of the Peterson olefination reaction. Desilylation of 15a with tetrabutylammonium fluoride (TBAF) followed by two consecutive electrocyclizations resulted in the formation of the corresponding benzocyclobutadiene 17a, leading to the four angular dimers 18a−d. The use of cyclopentadiene to capture 17a afforded the Diels−Alder adduct 19. Treatment of 15b with TBAF produced only one angular dimer 21. On the other hand, the presence of a phenyl substituent on the four-membered ring directed the dimerization of benzocyclobutadiene 17c toward the linear dimer 23, which then underwent a facile thermal rearrangement to dibenzocyclooctadiene 24. Interestingly, benzocyclobutadienes 17d and 17e having an alkenyl substituent on the four-membered ring dimerized via a formal [4 + 4] cycloaddition to the 1,5-cyclooctadienes 26 and 32, resp...
MxB Restricts HIV-1 by Targeting the Tri-hexamer Interface of the Viral Capsid.

Summary The human antiviral protein MxB is a restriction factor that fights HIV infection. Previous experiments have demonstrated that MxB targets the HIV capsid, a protein shell that protects the viral genome. To make the conical-shaped capsid, HIV CA proteins are organized into a lattice composed of hexamer and pentamer building blocks, providing many interfaces for host proteins to recognize. Through extensive biochemical and biophysical studies and molecular dynamics simulations, we show that MxB is targeting the HIV capsid by recognizing the region created at the intersection of three CA hexamers. We are further able to map this interaction to a few CA residues, located in a negatively charged well at the interface between the three CA hexamers. This work provides detailed residue-level mapping of the targeted capsid interface and how MxB interacts. This information could inspire the development of capsid-targeting therapies for HIV.
Microwave-assisted zinc chloride-catalyzed synthesis of substituted pyrroles from homopropargyl azides

Abstract Ligand-free 5-endo-dig cyclization of 1,4- and 1,2,4-substituted but-3-yn-1-yl (homopropargyl) azides in the presence of zinc chloride (usually 20 mol %) in dichloroethane at elevated temperature provides 2,5-di- and 2,3,5-trisubstituted pyrroles in high to moderate yields (91–41%). Both conventional and microwave protocols furnished comparable results. A structure of 2-(4-fluorophenyl)-5-(4-methylphenyl)-1H-pyrrole was confirmed by X-ray crystallography.
Total synthesis of the putative structure of the lupin alkaloid plumerinine.

A stereocontrolled synthesis of quinolizidine 1, the reported structure of plumerinine, has been accomplished in 10 steps from 4-methoxypyridine. The key step is a highly facial selective intramolecular [2 + 2] photocycloaddition of a 2,3-dihydro-4-pyridone. The reported spectral data for plumerinine did not match that of our synthetic 1.
Incidence of Dementia and Alzheimer Disease Over Time: A Meta-Analysis.

Background/objectives Population-based incidence estimates of dementia and Alzheimer disease (AD) provide important information for public health policy and resource allocation. We conducted a meta-analysis of published studies that reported age-specific incidence rates of dementia and AD to determine whether dementia and AD incidence rates are changing over time. Design PubMed and MEDLINE were searched for publications through June 30, 2017, using key words "dementia", "Alzheimer", and "incidence." Inclusion criteria for the meta-analysis are: (1) population-based studies using personal interviews and direct examinations of the study subjects, (2) standardized clinical diagnosis criteria, (3) reporting age-specific incidence rates, (4) published in English, and (5) sample size of 500 or greater and length of follow-up of 2 years or greater. Mixed-effects models were used to determine the association between birth year and incidence rates. Measurements Age-specific dementia/AD incidence rates and their standard errors reported in each study. Results Thirty-eight articles with 53 cohorts on dementia incidence and 31 articles with 35 cohorts on AD incidence met the inclusion criteria. There were significant associations between later birth years and decreased dementia incidence rates in all three age groups (65-74, 75-84, and 85 years and older). There were no significant associations between birth year and AD incident rates in any of the three age groups. In particular, AD incidence rates reported from Western countries stayed steady in all age groups, while studies in non-Western countries showed significantly increased AD incidence rates for the 65 to 74 years age group (odds ratio = 2.78; P = .04), but a nonsignificant association for the 75 to 84 or 85 years and older groups. Conclusion Dementia incidence declined over the past four decades, but AD incidence did not decline. Further research, especially from non-Western countries, is needed to elucidate the mechanism underlying the trends in dementia and AD incidence over time.
Regime shifts and hysteresis in the pitcher-plant microecosystem

Abstract Changes in environmental conditions can lead to rapid shifts in the state of an ecosystem (“regime shifts”), which, even after the environment has returned to previous conditions, subsequently recovers slowly to the previous state (“hysteresis”). Large spatial and temporal scales of dynamics, and the lack of frameworks linking observations to models, are challenges to understanding and predicting ecosystem responses to perturbations. The naturally-occurring microecosystem inside leaves of the northern pitcher plant (Sarracenia purpurea) exhibits oligotrophic and eutrophic states that can be induced by adding insect prey. Here, we further develop a model for simulating these dynamics, parameterize it using data from a prey addition experiment and conduct a sensitivity analysis to identify critical zones within the parameter space. Simulations illustrate that the microecosystem model displays regime shifts and hysteresis. Parallel results were observed in the plant itself after experimental enrichment with prey. Decomposition rate of prey was the main driver of system dynamics, including the time the system remains in an anoxic state and the rate of return to an oxygenated state. Biological oxygen demand influenced the shape of the system's return trajectory. The combination of simulated results, sensitivity analysis and use of empirical results to parameterize the model more precisely demonstrates that the Sarracenia microecosystem model displays behaviors qualitatively similar to models of larger ecological systems.
Vinylcyclopropyl TMM diyls: access to eight-membered rings

Abstract Vinylcyclopropyl substituted diazenes (e.g. 1 and 15 ) rearrange when heated. The chemistry takes place via the formation of a trimethylenemethane (TMM) diyl and provides access to eight-membered rings. When the cyclopropane is fused to a five-membered ring (e.g. 15 ) rearrangement leads to a structure resembling the taxotere framework.
A series of spirocyclic analogues as potent inhibitors of bacterial phenylalanyl-tRNA synthetases.

Abstract We have identified a series of spirocyclic furan and pyrrolidine inhibitors of Enterococeus faecalis and Staphylococcus aureus phenylalanyl-tRNA synthetases. The most potent analogue 1b showed IC50=5 nM (E. faecalis PheRS) and IC50=2 nM (S. aureus PheRS) with high selectivity over the human enzyme. The crystal X-ray structure of analogue 1b was determined.
Effects of acute physical activity on NIH toolbox-measured cognitive functions among children in authentic education settings

Abstract Introduction Identifying a dose of physical activity (PA) that can improve cognitive function in children has important implications for school-day PA recommendations. Researchers and educators have interest in this link as it relates to both health and academic performance. This study examined the dose-response relationship between PA and improvement in cognition in a sample of fifth and sixth grade students. Methods Participants (n = 156) from eight classes each completed two of four different cognitive assessments on an iPad, both before and after exposure to one of four randomized, 10-min PA conditions (sedentary, light, moderate, and vigorous). Conditions were standardized through use of videos to lead movement, and participants wore accelerometers to confirm fidelity to PA condition. The four cognitive assessments were selected from the NIH Toolbox Cognition Battery, and included Dimensional Change Card Sort, Flanker, Pattern Comparison, and Picture Sequence Memory tests. Hierarchical linear regression models were used to estimate the effects of condition on each test using an intention to treat analysis. Results Fidelity to PA condition was acceptable for sedentary and light conditions, but became less precise for moderate and vigorous conditions. No significant time by condition interaction was observed for any of the cognitive assessment scores. Conclusions Results did not substantiate a dose-response link between PA intensity and selected measures of cognitive function. More research is needed to investigate the potentially nuanced effects of short bouts of PA on cognitive functioning in children.
On Difficulties of Cross-Lingual Transfer with Order Differences: A Case Study on Dependency Parsing

Different languages might have different word orders. In this paper, we investigate crosslingual transfer and posit that an orderagnostic model will perform better when transferring to distant foreign languages. To test our hypothesis, we train dependency parsers on an English corpus and evaluate their transfer performance on 30 other languages. Specifically, we compare encoders and decoders based on Recurrent Neural Networks (RNNs) and modified self-attentive architectures. The former relies on sequential information while the latter is more flexible at modeling word order. Rigorous experiments and detailed analysis shows that RNN-based architectures transfer well to languages that are close to English, while self-attentive models have better overall cross-lingual transferability and perform especially well on distant languages.
Syntheses, structures, and characterization of new lead(II)-tellurium(IV)-oxide halides: Pb3Te2O6X2 and Pb3TeO4X2 (X = Cl or Br).

The syntheses, structures, and characterization of four new lead(II)−tellurium(IV)−oxide halides, Pb3Te2O6X2 and Pb3TeO4X2 (X = Cl or Br) are reported. The materials are synthesized by solid-state techniques, using Pb3O2Cl2 or Pb3O2Br2 and TeO2 as reagents. The compounds have three-dimensional structural topologies consisting of lead−oxide halide polyhedra connected to tellurium oxide groups. In addition, the Pb2+ and Te4+ cations are in asymmetric coordination environments attributable to their stereoactive lone pair. We also demonstrate that Pb3Te2O6X2 and Pb2TeO4X2 can be interconverted reversibly through the loss or addition of TeO2. X-ray data: Pb3Te2O6Cl2, monoclinic, space group C2/m (No. 12), a = 16.4417(11) A, b = 5.6295(4) A, c = 10.8894(7) A, β = 103.0130(10)°, Z = 4; Pb3Te2O6Br2, monoclinic, space group C2/m (No. 12), a = 16.8911(8) A, b = 5.6804(2) A, c = 11.0418(5) A, β = 104.253(2)°, Z = 4; Pb3TeO4Cl2, orthorhombic, space group Bmmb (No. 63), a = 5.576(1) A, b = 5.559(1) A, c = 12.4929(6) ...
Flattening NTRU for Evaluation Key Free Homomorphic Encryption

We propose a new FHE scheme F-NTRU that adopts the flattening technique proposed in GSW to derive an NTRU based scheme that (similar to GSW) does not require evaluation keys or key switching. Our scheme eliminates the decision small polynomial ratio (DSPR) assumption but relies only on the standard R-LWE assumption. It uses wide key distributions, and hence is immune to the Subfield Lattice Attack. In practice, our scheme achieves competitive timings compared to the existing schemes. We are able to compute a homomorphic multiplication in 5.8 msec and 17.6 msec for 5 and 30 levels, respectively, without amortization. Furthermore, our scheme features small ciphertexts, e.g. 567 KB for 30 levels, and eliminates the need for storing and managing costly evaluation keys. In addition, we present a slightly modified version of F-NTRU that is capable to support integer operations with a very large message space along with noise analysis for all cases. The assurance gained by using wide key distributions along with the message space flexibility of the scheme, i.e. bits, binary polynomials, and integers with a large message space, allows the use the proposed scheme in a wide array of applications.
Synthetic ferric sulfate trihydrate, Fe2(SO4)3·3H2O, a new ferric sulfate salt

Ferric sulfate trihydrate has been synthesized at 403 K under hydro­thermal conditions. The structure consists of quadruple chains of [Fe2(SO4)3(H2O)3]^0_{\infty} parallel to [010]. Each quadruple chain is composed of equal proportions of FeO4(H2O)2 octa­hedra and FeO5(H2O) octa­hedra sharing corners with SO4 tetra­hedra. The chains are joined to each other by hydrogen bonds. This compound is a new hydration state of Fe2(SO4)3·nH2O; minerals with n = 0, 5, 7.25–7.75, 9 and 11 are found in nature.
Chiral topological phases in designed mechanical networks

Mass-spring networks (MSNs) have long been used as approximate descriptions of many biological and engineered systems, from actomyosin networks to mechanical trusses. In the last decade, MSNs have re-attracted theoretical interest as models for phononic metamaterials with exotic properties such as negative Poisson's ratio, negative effective mass, or gapped vibrational spectra. A numerical advantage of MSNs is their tuneability, which allows the inverse design of materials with pre-specified bandgaps. Building on this fact, we demonstrate here that designed MSNs, when subjected to Coriolis forces, can host topologically protected chiral edge modes at predetermined frequencies, thus enabling robust unidirectional transmission of mechanical waves. Similar to other recently discovered topological materials, the topological phases of MSNs can be classified by a Chern invariant related to time-reversal symmetry breaking.
Direct Numerical Simulation of Transition Control via Local Dynamic Surface Modification

Direct numerical simulations were carried out in order to reproduce the generation and control of transition on a flat plate by means of local dynamic surface modification. The configuration and fl...
Generating set for nonzero determinant links under skein relation

Abstract Traditionally introduced in terms of advanced topological constructions, many link invariants may also be defined in much simpler terms given their values on a few initial links and a recursive formula on a skein triangle. The crucial question to ask is how many initial values are necessary to completely determine such a link invariant. We focus on a specific class of invariants known as nonzero determinant link invariants and restate the objective by considering a set S of links subject to a closure condition under a given skein triangle. Then the aim is to determine a minimal set of initial generators so that S is the set of all links with nonzero determinant. We show that only the unknot is required as a generator if the skein triangle is unoriented. For oriented skein triangles, we show that the unknot and Hopf link orientations form a set of generators.
Replicator degrees of freedom allow publication of misleading failures to replicate.

In recent years, the field of psychology has begun to conduct replication tests on a large scale. Here, we show that “replicator degrees of freedom” make it far too easy to obtain and publish false-negative replication results, even while appearing to adhere to strict methodological standards. Specifically, using data from an ongoing debate, we show that commonly exercised flexibility at the experimental design and data analysis stages of replication testing can make it appear that a finding was not replicated when, in fact, it was. The debate that we focus on is representative, on key dimensions, of a large number of other replication tests in psychology that have been published in recent years, suggesting that the lessons of this analysis may be far reaching. The problems with current practice in replication science that we uncover here are particularly worrisome because they are not adequately addressed by the field’s standard remedies, including preregistration. Implications for how the field could develop more effective methodological standards for replication are discussed.
Chip firing on Dynkin diagrams and McKay quivers

This paper establishes new connections between the representation theory of finite groups and sandpile dynamics. Two classes of avalanche-finite matrices and their critical groups (integer cokernels) are studied from the viewpoint of chip-firing/sandpile dynamics, namely, the Cartan matrices of finite root systems and the McKay–Cartan matrices for finite subgroups G of general linear groups. In the root system case, the recurrent and superstable configurations are identified explicitly and are related to minuscule dominant weights. In the McKay–Cartan case for finite subgroups of the special linear group, the cokernel is related to the abelianization of the subgroup G. In the special case of the classical McKay correspondence, the critical group and the abelianization are shown to be isomorphic.
Electric propulsion reliability: Statistical analysis of on-orbit anomalies and comparative analysis of electric versus chemical propulsion failure rates

Abstract With a few hundred spacecraft launched to date with electric propulsion (EP), it is possible to conduct an epidemiological study of EP's on orbit reliability. The first objective of the present work was to undertake such a study and analyze EP's track record of on orbit anomalies and failures by different covariates. The second objective was to provide a comparative analysis of EP's failure rates with those of chemical propulsion. Satellite operators, manufacturers, and insurers will make reliability- and risk-informed decisions regarding the adoption and promotion of EP on board spacecraft. This work provides evidence-based support for such decisions. After a thorough data collection, 162 EP-equipped satellites launched between January 1997 and December 2015 were included in our dataset for analysis. Several statistical analyses were conducted, at the aggregate level and then with the data stratified by severity of the anomaly, by orbit type, and by EP technology. Mean Time To Anomaly (MTTA) and the distribution of the time to (minor/major) anomaly were investigated, as well as anomaly rates. The important findings in this work include the following: (1) Post-2005, EP's reliability has outperformed that of chemical propulsion; (2) Hall thrusters have robustly outperformed chemical propulsion, and they maintain a small but shrinking reliability advantage over gridded ion engines. Other results were also provided, for example the differentials in MTTA of minor and major anomalies for gridded ion engines and Hall thrusters. It was shown that: (3) Hall thrusters exhibit minor anomalies very early on orbit, which might be indicative of infant anomalies, and thus would benefit from better ground testing and acceptance procedures; (4) Strong evidence exists that EP anomalies (onset and likelihood) and orbit type are dependent, a dependence likely mediated by either the space environment or differences in thrusters duty cycles; (5) Gridded ion thrusters exhibit both infant and wear-out failures, and thus would benefit from a reliability growth program that addresses both these types of problems.
Per-Tensor Fixed-Point Quantization of the Back-Propagation Algorithm.

The high computational and parameter complexity of neural networks makes their training very slow and difficult to deploy on energy and storage-constrained computing systems. Many network complexity reduction techniques have been proposed including fixed-point implementation. However, a systematic approach for designing full fixed-point training and inference of deep neural networks remains elusive. We describe a precision assignment methodology for neural network training in which all network parameters, i.e., activations and weights in the feedforward path, gradients and weight accumulators in the feedback path, are assigned close to minimal precision. The precision assignment is derived analytically and enables tracking the convergence behavior of the full precision training, known to converge a priori. Thus, our work leads to a systematic methodology of determining suitable precision for fixed-point training. The near optimality (minimality) of the resulting precision assignment is validated empirically for four networks on the CIFAR-10, CIFAR-100, and SVHN datasets. The complexity reduction arising from our approach is compared with other fixed-point neural network designs.
Algebraic entropy and the action of mapping class groups on character varieties

Abstract We extend the definition of algebraic entropy to endomorphisms of affine varieties. We then calculate the algebraic entropy of the action of elements of mapping class groups on various character varieties, and show that it is equal to a quantity we call the spectral radius, a generalization of the dilatation of a pseudo-Anosov mapping class. Our calculations are compatible with all known calculations of the topological entropy of this action.
Six-vertex Models and the GUE-corners Process

In this paper we consider a class of probability distributions on the six-vertex model from statistical mechanics, which originate from the higher spin vertex models of https://arxiv.org/abs/1601.05770. We define operators, inspired by the Macdonald difference operators, which extract various correlation functions, measuring the probability of observing different arrow configurations. The development of our operators is largely based on the properties of a remarkable family of symmetric rational functions, which were previously studied in https://arxiv.org/abs/1410.0976. For the class of models we consider, the correlation functions can be expressed in terms of multiple contour integrals, which are suitable for asymptotic analysis. For a particular choice of parameters we analyze the limit of the correlation functions through a steepest descent method. Combining this asymptotic statement with some new results about Gibbs measures on Gelfand-Tsetlin cones and patterns, we show that the asymptotic behavior of our six-vertex model near the boundary is described by the GUE-corners process.
The extremal symmetry of arithmetic simplicial complexes

Abstract Let G be a higher-rank semisimple Lie group over a nonarchimedean local field, for example G = PGL ( n , Q P ) . To any lattice L in G there is an associated simplicial complex B L , given by the quotient by L of the Bruhat–Tits building associated to G . In this paper prove that the simplicial structure B L exhibits some remarkable and extremal symmetry properties, in particular when compared to any other simplicial structure on (any cover of) B L .
Hamiltonian-based algorithm for relaxed optimal control

This paper concerns a first-order algorithmic technique for a class of optimal control problems defined on switched-mode hybrid systems. The salient feature of the algorithm is that it avoids the computation of Frechet or Gâteaux derivatives of the cost functional, which can be time consuming, but rather moves in a projected-gradient direction that is easily computable (for a class of problems) and does not require any explicit derivatives. The algorithm is applicable to a class of problems where a pointwise minimizer of the Hamiltonian is computable by a simple formula, and this includes many problems that arise in theory and applications. The natural setting for the algorithm is the space of continuous-time relaxed controls, whose special structure renders the analysis simpler than the setting of ordinary controls. While the space of relaxed controls has theoretical advantages, its elements are abstract entities that may not be amenable to computation. Therefore, a key feature of the algorithm is that it computes adequate approximations to relaxed controls without loosing its theoretical convergence properties. Simulation results, including cpu times, support the theoretical developments.
The Geometric Block Model.

To capture the inherent geometric features of many community detection problems, we propose to use a new random graph model of communities that we call a Geometric Block Model. The geometric block model generalizes the random geometric graphs in the same way that the well-studied stochastic block model generalizes the Erdos-Renyi random graphs. It is also a natural extension of random community models inspired by the recent theoretical and practical advancement in community detection. While being a topic of fundamental theoretical interest, our main contribution is to show that many practical community structures are better explained by the geometric block model. We also show that a simple triangle-counting algorithm to detect communities in the geometric block model is near-optimal. Indeed, even in the regime where the average degree of the graph grows only logarithmically with the number of vertices (sparse-graph), we show that this algorithm performs extremely well, both theoretically and practically. In contrast, the triangle-counting algorithm is far from being optimum for the stochastic block model. We simulate our results on both real and synthetic datasets to show superior performance of both the new model as well as our algorithm.
Maximizing Influence in an Ising Network: A Mean-Field Optimal Solution

Influence maximization in social networks has typically been studied in the context of contagion models and irreversible processes. In this paper, we consider an alternate model that treats individual opinions as spins in an Ising system at dynamic equilibrium. We formalize the \textit{Ising influence maximization} problem, which has a natural physical interpretation as maximizing the magnetization given a budget of external magnetic field. Under the mean-field (MF) approximation, we present a gradient ascent algorithm that uses the susceptibility to efficiently calculate local maxima of the magnetization, and we develop a number of sufficient conditions for when the MF magnetization is concave and our algorithm converges to a global optimum. We apply our algorithm on random and real-world networks, demonstrating, remarkably, that the MF optimal external fields (i.e., the external fields which maximize the MF magnetization) exhibit a phase transition from focusing on high-degree individuals at high temperatures to focusing on low-degree individuals at low temperatures. We also establish a number of novel results about the structure of steady-states in the ferromagnetic MF Ising model on general graphs, which are of independent interest.
Learning Latent Representations for Speech Generation and Transformation.

An ability to model a generative process and learn a latent representation for speech in an unsupervised fashion will be crucial to process vast quantities of unlabelled speech data. Recently, deep probabilistic generative models such as Variational Autoencoders (VAEs) have achieved tremendous success in modeling natural images. In this paper, we apply a convolutional VAE to model the generative process of natural speech. We derive latent space arithmetic operations to disentangle learned latent representations. We demonstrate the capability of our model to modify the phonetic content or the speaker identity for speech segments using the derived operations, without the need for parallel supervisory data.