cssi/SciSciGPT-SciSciNet huggingface dataset:
Extreme temperatures and time use in China

How do people in developing countries respond to extreme temperatures? Using individual-level panel data over two decades and relying on plausibly exogenous variation in weather, we estimate how extreme temperatures affect time use in China. Extreme temperatures reduce time spent working, and this effect is largest for female farmers. Hot days reduce time spent by women on outdoor chores, but we find no such effects for men. Finally, hot days dramatically reduce time spent on childcare, reflecting large effects on home production. Taken together, our results suggest time use is an important margin of response to extreme temperatures.
Kinetics of Proton Transfer from 2-Nitro-4-X-phenylacetonitriles to Piperidine and Morpholine in Aqueous Me2SO. Solvent and Substituent Effects on Intrinsic Rate Constants. Transition State Imbalances

Rate constants ( ) for the deprotonation of 2-nitro-4-X-phenylacetonitrile, 2-X (X = NO2, SO2CH3, CN, CF3, Br, and Cl) by piperidine and morpholine and for the reverse reaction ( ) have been determined in 90% Me2SO−10% water, 50% Me2SO−50% water, and water (X = NO2, SO2CH3, CN only). Bronsted βB values (dlog /dp ), Bronsted αCH values (dlog /dlog ), and intrinsic rate constants (log ko = log(k1/q) for p − p + log(p/q) = 0) were calculated from these data. αCH is smaller than βB, implying an imbalance which is consistent with a transition state in which delocalization of the negative charge into the 2-nitrophenyl moiety lags behind proton transfer. A consequence of this imbalance is that the intrinsic rate constant decreases with increasing electron withdrawing strength of X. For π-acceptor substituents (NO2, SO2CH3, CN) there is a further decrease in ko due to a lag in the delocalization of the charge into X. The intrinsic rate constants depend very little on the Me2SO content of the solvent which is show...
Structure, Magnetism, and Colossal Magnetoresistance (CMR) of the Ternary Transition Metal Solid Solution Ca14-xEuxMnSb11 (0 < x < 14)

The solid solution of the ternary transition metal Zintl phase Ca 14-x Eu x MnSb 11 (0 < x < 14) has been prepared by heating a mixture of stoichiometric amounts of the elements in a two-zone furnace with T high = 1100 °C and T low = 1050 °C. The ternary transition metal compounds crystallize in the tetragonal space group I4 1 /acd and are isostructural with the Zintl compound Ca 14 AlSb 11 . The lattice parameters of the Ca 14-x Eu x MnSb 11 compounds linearly increase with increasing Eu substitution for Ca. The Eu atoms preferentially occupy the C a (2) site first and subsequently occupy Ca(4), Ca(1), and Ca(3), in order, among the four crystallographically inequivalent Ca sites. Temperature-dependent magnetic susceptibility measurements of the solid solution reveal that Eu replacement for Ca induces complex magnetic interactions in the compound, from simple ferromagnetic interactions for Ca 14 -MnSb 11 to ferrimagnetic interactions for Eu 14 MnSb 11 , because of the Eu 2+ (4f 7 ) magnetic moment. The paramagnetic Curie temperature of the Ca 14-x Eu x MnSb 11 compounds shows an interesting change with varying x, and the magnetic easy axis gradually changes in the solid solution from perpendicular (for Ca 14 MnSb 11 ) to parallel (for Eu 14 MnSb 11 ) to the crystal c axis. The electrical transport properties of the Ca 14-x Eu x MnSb 11 (x = 0, 3, 11) compounds show a close relation to their magnetic properties and are compared to the previous results for Ca 14-x Eu x MnSb 11 (x = 13, 14). The influence of Eu doping on the structural and physical property of Ca 14-x Eu x MnSb 11 is discussed in terms of the site preferences of Eu for the four different Ca sites.
The chemistry of vicinal tricarbonyls. Formation of oxomalondiamides

Abstract Oxomalondiamides and related systems are readily formed from derivatives of oxalic acid monoamides. The monoamides are converted to labile triacyl nitriles through cyano ylide intermediates for further coupling with amines and other nucleophiles.
A straightforward synthesis of 3-acylphospholes.

The reaction of 2,5-diphenylphospholide, first with acyl chlorides, then with tBuOK, provides a direct access to 3-acyl-2,5-diphenylphospholides via a 1H-, 2H-, 3H-phosphole equilibrium.
Remarkably effective and simple syntheses of enantiomerically pure secondary carbinols from achiral ketones

Abstract The chiral oxazaborolidine (1)-catalyzed reduction of the ketones 2, 6 and 8 has provided simple access to the chiral secondary carbinols 3, 7, and 9 in very high enantiomeric purity.
Structure, bonding, and magnetic response in two complex borides: Zr2Fe1−δRu5+δB2 and Zr2Fe1−δ(Ru1−xRhx)5+δB2

Abstract Polycrystalline samples of two complex intermetallic borides Zr 2 Fe 1− δ Ru 5+ δ B 2 and Zr 2 Fe 1− δ (Ru 1− x Rh x ) 5+ δ B 2 ( δ =ca. 0.10; x =0.20) were synthesized by high-temperature methods and characterized by single-crystal X-ray diffraction, energy dispersive spectroscopy, and magnetization measurements. Both structures are variants of Sc 2 Fe(Ru 1− x Rh x ) 5 B 2 and crystallize in the space group P 4/ mbm (no. 127) with the Ti 3 Co 5 B 2 -type structure. These structures contain single-atom, Fe-rich Fe/Ru or Fe/Ru/Rh chains along the c -axis with an interatomic metal-metal distance of 3.078(1) A, a feature which makes them viable for possible low-dimensional temperature-dependent magnetic behavior. Magnetization measurements indicated weak ferrimagnetic ordering with ordering temperatures ca. 230 K for both specimens. Tight-binding electronic structure calculations on a model “Zr 2 FeRu 5 B 2 ” using LDA yielded a narrow peak at the Fermi level assigned to Fe–Fe antibonding interactions along the c -axis, a result that indicates an electronic instability toward ferromagnetic coupling along these chains. Spin-polarized calculations of various magnetic models were examined to identify possible magnetic ordering within and between the single-atom, Fe-rich chains.
Potential mechanisms linking SIRT activity and hypoxic 2-hydroxyglutarate generation: no role for direct enzyme (de)acetylation

2-Hydroxyglutarate (2-HG) is a hypoxic metabolite with potentially important epigenetic signaling roles. The mechanisms underlying 2-HG generation are poorly understood, but evidence suggests a potential regulatory role for the sirtuin family of lysine deacetylases. Thus, we hypothesized that the acetylation status of the major 2-HG-generating enzymes [lactate dehydrogenase (LDH), isocitrate dehydrogenase (IDH) and malate dehydrogenase (MDH)] may govern their 2-HG-generating activity. In vitro acetylation of these enzymes, with confirmation by western blotting, mass spectrometry, reversibility by recombinant sirtuins and an assay for global lysine occupancy, yielded no effect on 2-HG-generating activity. In addition, while elevated 2-HG in hypoxia is associated with the activation of lysine deacetylases, we found that mice lacking mitochondrial SIRT3 exhibited hyperacetylation and elevated 2-HG. These data suggest that there is no direct link between enzyme acetylation and 2-HG production. Furthermore, our observed effects of in vitro acetylation on the canonical activities of IDH, MDH and LDH appeared to contrast with previous findings wherein acetyl-mimetic lysine mutations resulted in the inhibition of these enzymes. Overall, these data suggest that a causal relationship should not be assumed between acetylation of metabolic enzymes and their activities, canonical or otherwise.
Search for Dark Matter

The search for dark matter is a very wide and active field of research, and I necessarily concentrate here only in some aspects of it. I will review the prospects for direct and indirect dark matter searches of Weakly Interacting Massive Particles in the dark halo of our galaxy and focus in particular on the data of GLAST, PAMELA and DAMA.
Associations between sexual habits, menstrual hygiene practices, demographics and the vaginal microbiome as revealed by Bayesian network analysis.

The vaginal microbiome plays an influential role in several disease states in reproductive age women, including bacterial vaginosis (BV). While demographic characteristics are associated with differences in vaginal microbiome community structure, little is known about the influence of sexual and hygiene habits. Furthermore, associations between the vaginal microbiome and risk symptoms of bacterial vaginosis have not been fully elucidated. Using Bayesian network (BN) analysis of 16S rRNA gene sequence results, demographic and extensive questionnaire data, we describe both novel and previously documented associations between habits of women and their vaginal microbiome. The BN analysis approach shows promise in uncovering complex associations between disparate data types. Our findings based on this approach support published associations between specific microbiome members (e.g., Eggerthella, Gardnerella, Dialister, Sneathia and Ruminococcaceae), the Nugent score (a BV diagnostic) and vaginal pH (a risk symptom of BV). Additionally, we found that several microbiome members were directly connected to other risk symptoms of BV (such as vaginal discharge, odor, itch, irritation, and yeast infection) including L. jensenii, Corynebacteria, and Proteobacteria. No direct connections were found between the Nugent Score and risk symptoms of BV other than pH, indicating that the Nugent Score may not be the most useful criteria for assessment of clinical BV. We also found that demographics (i.e., age, ethnicity, previous pregnancy) were associated with the presence/absence of specific vaginal microbes. The resulting BN revealed several as-yet undocumented associations between birth control usage, menstrual hygiene practices and specific microbiome members. Many of these complex relationships were not identified using common analytical methods, i.e., ordination and PERMANOVA. While these associations require confirmatory follow-up study, our findings strongly suggest that future studies of the vaginal microbiome and vaginal pathologies should include detailed surveys of participants’ sanitary, sexual and birth control habits, as these can act as confounders in the relationship between the microbiome and disease. Although the BN approach is powerful in revealing complex associations within multidimensional datasets, the need in some cases to discretize the data for use in BN analysis can result in loss of information. Future research is required to alleviate such limitations in constructing BN networks. Large sample sizes are also required in order to allow for the incorporation of a large number of variables (nodes) into the BN, particularly when studying associations between metadata and the microbiome. We believe that this approach is of great value, complementing other methods, to further our understanding of complex associations characteristic of microbiome research.
Syntheses of new porphyrin-type photosensitizers for photodynamic therapy

In the first part of this paper, syntheses of water-soluble photosensitizers for use in photodynamic therapy are described. Vinylporphyrins and vinylchlorins react with N.N- dimethylmethyleneammonium iodide (Eschenmoser's reagent) to give 2- (dimethylaminomethyl)vinyl derivatives which can be readily quaternized with methyl iodide to give highly water-soluble quaternary ammonium salts. Deuteroporphyrin-IX dimethyl ester undergoes direct substitution with dimethylaminomethyl at the nuclear 2- and 4-positions. The second part of this report describes the syntheses of bacteriochlorin analogues of natural chlorophyll derivatives; these are obtained by osmium tetraoxide oxidation of chlorins to give vic-dihydroxybacteriochlorins. Acid catalyzed pinacol-pinacolone rearrangements of a number of vic-dihydroxybacterochlorins to given ketobacteriochlorins are described, and the chemistry of the rearrangement is investigated. Biological studies of all sensitizers described will be reported elsewhere.
Photolytic, thermal, addition, and cycloaddition reactions of 2-diazo-5,6- and -3,8-disubstituted acenaphthenones.

Preparation and varied thermal and photolytic reactions of 2-diazo-5,6-(disubstituted)acenaphthenones (11a−d) and 2-diazo-3,8-dimethoxyacenaphthenone (12) are reported. Alcohols react thermally and photolytically with 11a−c with losses of N2 to yield 2-alkoxynaphthenones (24a,b and 47a,b) and acenaphthenones (25 and 48a,b). Aniline and diphenylamine are converted by 11a−c at 180 °C to acenaph[1,2-b]indoles (29a,b and 53a,b). Thermolyses of 11a−c at ∼450 °C (0.15 mmHg) yield reduction products 25 and 48a,b, respectively. Wolff rearrangements to 1,8-naphthyleneketenes (15a−d) and/or their derivatives are not observed in the above experiments. Oxygen converts 11a−c thermally to acenaphthenequinones (19a−c) and/or 1,8-naphthalic anhydrides. Insertion, addition, substitution, and/or isomerization reactions occur upon irradiation of 2-diazoacenaphthenones in cyclohexane, benzene, and tetrahydrofuran. Photolysis of 11d in benzene in the presence of O2 yields the insertion−oxidation product 2-hydroxy-5,6-dinitro-...
Synthesis of Unsymmetrical Vicinal Diols Using Titanium Aminotroponiminate Alkyl Complexes

A novel, multicomponent method to prepare vicinal diols from titanium dialkyl complexes, CO, and carbonyl compounds is presented. The reaction involves sequential coupling of aminotroponiminate-sup...
Extraocular motoneuron pools develop along a dorsoventral axis in zebrafish, Danio rerio

Both spatial and temporal cues determine the fate of immature neurons. A major challenge at the interface of developmental and systems neuroscience is to relate this spatiotemporal trajectory of maturation to circuit-level functional organization. This study examined the development of two extraocular motor nuclei (nIII and nIV), structures in which a motoneuron's identity, or choice of muscle partner, defines its behavioral role. We used retro-orbital dye fills, in combination with fluorescent markers for motoneuron location and birthdate, to probe spatial and temporal organization of the oculomotor (nIII) and trochlear (nIV) nuclei in the larval zebrafish. We describe a dorsoventral organization of the four nIII motoneuron pools, in which inferior and medial rectus motoneurons occupy dorsal nIII, while inferior oblique and superior rectus motoneurons occupy distinct divisions of ventral nIII. Dorsal nIII motoneurons are, moreover, born before motoneurons of ventral nIII and nIV. The order of neurogenesis can therefore account for the dorsoventral organization of nIII and may play a primary role in determining motoneuron identity. We propose that the temporal development of extraocular motoneurons plays a key role in assembling a functional oculomotor circuit. J. Comp. Neurol. 525:65-78, 2017. © 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.
The stereoselective preparation of fluorinated dienes via stille-liebeskind cross-coupling reactions

Readily prepared fluorinated vinylstannane reagents stereoselectively undergo Stille-Liebeskind cross-coupling reactions with vinyl halides (including fluorine-containing vinyl halides) with Pd(PPh 3 ) 4 /CuI catalysis.
Synthesis, structure and physical properties of the new Zintl phases Eu11Zn6Sb12 and Eu11Cd6Sb12

Reported are the syntheses, crystal structure determinations from single-crystal X-ray diffraction, and magnetic properties of two new ternary compounds, Eu{sub 11}Cd{sub 6}Sb{sub 12} and Eu{sub 11}Zn{sub 6}Sb{sub 12}. Both crystallize with the complex Sr{sub 11}Cd{sub 6}Sb{sub 12} structure type-monoclinic, space group C2/m (no. 12), Z=2, with unit cell parameters a=31.979(4) A, b=4.5981(5) A, c=12.3499(14) A, {beta}=109.675(1){sup o} for Eu{sub 11}Zn{sub 6}Sb{sub 12}, and a=32.507(2) A, b=4.7294(3) A, c=12.4158(8) A, {beta}=109.972(1){sup o} for Eu{sub 11}Cd{sub 6}Sb{sub 12}. Their crystal structures are best described as made up of polyanionic {sub {infinity}}{sup 1}[Zn{sub 6}Sb{sub 12}]{sup 22-} and {sub {infinity}}{sup 1}[Cd{sub 6}Sb{sub 12}]{sup 22-} ribbons of corner-shared ZnSb{sub 4} and CdSb{sub 4} tetrahedra and Eu{sup 2+} cations. A notable characteristic of these structures is the presence of Sb-Sb interactions, which exist between two tetrahedra from adjacent layers, giving rise to unique channels. Detailed structure analyses shows that similar bonding arrangements are seen in much simpler structure types, such as Ca{sub 3}AlAs{sub 3} and Ca{sub 5}Ga{sub 2}As{sub 6} and the structure can be rationalized as their intergrowth. Temperature-dependent magnetization measurements indicate that Eu{sub 11}Cd{sub 6}Sb{sub 12} orders anti-ferromagnetically below 7.5 K, while Eu{sub 11}Zn{sub 6}Sb{sub 12} does not order down to 5 K. Resistivity measurementsmore » confirm that Eu{sub 11}Cd{sub 6}Sb{sub 12} is poorly metallic, as expected for a Zintl phase. - Graphical abstract: The synthesis, structure determination from single-crystal X-ray diffraction and magnetic properties of Eu{sub 11}Zn{sub 6}Sb{sub 12} and Eu{sub 11}Cd{sub 6}Sb{sub 12} are reported. Both compounds crystallize with the monoclinic space group C2/m, and their structure can be viewed as built of ZnSb{sub 4} or CdSb{sub 4} tetrahedra, which are connected through common corners and exo-bonds.« less
Type 2 Intramolecular N-Acylnitroso Diels−Alder Reaction: Stereoselective Synthesis of Bridged Bicyclic Oxazinolactams

[reaction: see text] The type 2 intramolecular N-acylnitroso Diels-Alder reaction has been employed for the synthesis of substituted bridged bicyclic oxazinolactams. Upon oxidation of hydroxamic acid 6, a 3-benzylated oxazinolactam (7) was synthesized with complete diastereoselectivity. Elaboration of cycloadduct 7 liberated a cis-3,7-disubstituted azocin-2-one (9).
The combination of 2-NsNH2/NCS and MeCN as the nitrogen sources for the regio- and stereoselective formation of imidazolines from α,β-unsaturated ketones

Abstract A new nitrogen source combination was found for the regio- and stereoselective diamination of α,β-unsaturated ketones. This combination employs the readily available and inexpensive combination of NCS and 2-NsNH 2 as the electrophilic nitrogen source, and acetonitrile as the nucleophilic nitrogen source, respectively. The reaction is easily performed by mixing olefin, 2-NsNH 2 , NCS and 4 A molecular sieves in freshly distilled acetonitrile at room temperature. The reaction is chemoselective without the formation of any haloamine side products. A new aziridinium ion formed from enones and 2-NsNHCl is suggested to exist and to react with nitrile via a [2+3] cycloaddition mechanism, which is responsible for the excellent regio-, stereoselectivity of the resulting diamination products.
Temperature-Dependent Photoluminescence Properties of Tl[Ag(CN)2]: Formation of Luminescent Metal−Metal-Bonded Inorganic Exciplexes in the Solid State

The photoluminescence behavior of single crystals of Tl[Ag(CN)2] has been studied as a function of temperature. The 10 K spectra show a broad emission centered at about 420 nm and two excitation maxima at 301 and 314 nm. Exciting with each of these maxima gives a different temperature dependence for the corresponding emission spectra. This result correlates with the crystal structure of the compound which indicates the presence of two environments with Ag−Ag interactions. The fact that the emission band is largely red-shifted, broad, and structureless is consistent with exciplex emission. The results of extended Huckel and ab initio calculations indicate exciplex formation in the title compound. Our theoretical calculations show a deep potential well in the excited state with a Ag−Ag equilibrium distance of 2.45 A and a binding energy of 40.8 kcal/mol. The experimental and theoretical results in this study demonstrate the importance of excited-state Ag−Ag interactions leading to the formation of luminesce...
New Entry into β-Lactams via Reaction of Dimethoxycarbene with Isocyanates

Highly substituted β-lactams have been isolated as the major product of the reaction of dimethoxycarbene with selected isocyanates. This reaction offers the potential for rapid access into a variety of highly functionalized species.
Screening of bacteria at high temperatures to select nucleoside antibiotics producers

Publisher Summary This chapter describes screening of bacteria at high temperatures to select nucleoside antibiotics producers. Many nucleoside analogs have been found occurring naturally or have been synthesized chemically. The most commonly used methods for the chemical synthesis of nucleoside analogs include the sugar-based coupling reaction and modification of naturally occurring nucleosides. For the synthesis of stereo-specific nucleosides, microbial enzymes have been applied as a bio-catalyst in the chemical process. Adenine arabinoside is one of anitiviral agents that have been used as an anti-herpes agent. This compound is synthesized by chemical method and is later found in the culture filtrate of Streptomyces antibioticus. The enzyme substrate uracil arabinoside (ara-U) can be prepared from uridine through reaction with ethylene carbonate followed by the hydrolysis of cyclo-uridine (cyclo-U) by acid. Microorganisms from typeculture and natural resources are incubated at 30°C for 24 hours. The reaction temperature is considered very important and a key to the synthesis of ara-A.
Protocol of a research project ‘Projections of the burden of disease and disability in Finland – health policy prospects’ using cross-sectional health surveys and register-based follow-up

Introduction With the rapid ageing of the population in Europe, reliable estimates of the future development of the disease and disability burden as well as healthy life years in the older sections of the population are crucial. Meanwhile, the future prospects of the health and functional ability of the working-aged population are critical. The aims of the Projections of the burden of disease and disability in Finland – health policy prospects research project are to provide information about the long-term consequences of health-related behaviours of the population and to project the potential improvement of the burden of disease and disability based on realistic scenarios about the development of risk behaviours in the total population and its subgroups. Methods and analysis The analyses will be based on data from representative cross-sectional and longitudinal health examination surveys (HESs) conducted between 1972 to 2017 in Finland, and register data from several national administrative registers. Included HESs (FINRISK Surveys from 1972 to 2012, Mini-Finland Survey from 1978 to 1980, the Health 2000/2011 Surveys and the FinHealth 2017 Study) provide abundant information about biological and behavioural risk factors and the health and morbidity of the population. The modifiable risk factors used as predictors include hypertension, hyperlipidaemia, obesity, diabetes, physical inactivity, smoking, alcohol use and unfavourable diet. The main outcomes are ischaemic heart disease, cerebrovascular diseases, lung cancer, chronic obstructive pulmonary disease, Alzheimer’s disease and diabetes. Within the project, novel projection techniques of data-driven Bayesian hierarchical models to provide robust and comparable estimates will be developed. Ethics and dissemination The prevailing legislation and regulations have been followed for all surveys. Surveys since 1997 have been approved by the respective Ethics Committees covering the scope of this project. A written informed consent was obtained from participants since 1997. The outputs of the project will include 8 to 10 scientific papers in peer-reviewed journals.
Ca54In13B4–xH23+x: A Complex Metal Subhydride Featuring Ionic and Metallic Regions

Reactions of CaH2 with group 13 metals in a 1:1 Ca/Li flux mixture produce Ca54In13B4–xH23+x (2.4 < x < 4). This compound has a complex new structure [Im3, a = 16.3608(6) A, Z = 2] which can be viewed as a body-centered cubic array of Bergman-related clusters that are composed of a central indium atom surrounded by an icosahedron of 12 calcium atoms; hydride ions cap each face, forming a pentagonal dodecahedron that is further surrounded by a calcium shell. These In@Ca12@H20@Ca30 clusters are surrounded by a disordered calcium indium hydride network. Indium is not completely reduced by the flux; the structure features ionic hydride regions and metallic calcium indium regions, confirmed by electronic structure calculations and 1H and 115In solid-state NMR spectroscopy. This compound can therefore be viewed as a “subhydride”, akin to the alkali metal suboxides that feature ionic oxide clusters surrounded by metallic regions.
Microwave assisted synthesis of novel imidazo [2,1-b]thiazole derivative attached to quinoxalinones

3-(6-Phenylimidazo[2,1-b]thiazol-5-yl)quinoxalin-2(1H)-ones (qunoxalinone) (6a–q) have been synthesized by the reaction of ethyl 2-oxo-2-(6-phenylimidazo[2,1-b]thiazol-5-yl)acetates (4a–e) with suitably substituted o-phenylenediamines (5a–f) under microwave heating. The ethyl 2-oxo-2-(6-phenylimidazo[2,1-b]thiazol-5-yl)acetates (4a–e) were prepared by the reaction of 6-phenylimidazo[2,1-b]thiazoles (3a–e) with ethyl chlorooxoacetate in refluxing 1,4-dioxane whereas the thiazoles (3a–e) were synthesized by the reaction of 2-bromo-1-phenylethanones (2a–e) with thiazol-2-amine in refluxing acetone.
Studies on the applications of arene-ruthenium complexes in synthetic approaches to vancomycin: a mild procedure for the selective formation of chlorinated aryl ethers and triaryl diethers

Abstract Reactions of ( η 6 -1,3-dichlorobenzene)( η 5 -cyclopentadienyl)ruthenium hexafluorophosphate and ( η 6 -1,3-dichloro-2-methoxy-benzene)( η 5 -cyclopentadienyl)ruthenium hexafluorophosphate with ortho-chlorinated phenolates were found to proceed with excellent selectivity to generate monoarylated ethers under mild conditions. The second halogen may be displaced allowing the synthesis of unsymmetrical and symmetrical triaryl diethers. Methodology for sequential selective displacement of both chlorides by different nucleophiles and a photochemical method for demetallation of the arene-Ruthenium-Cp ( η 5 -cyclopentadienyl) complexes are reported.
Trans-2,5-Disubstituted Tetrahydrofurans via Addition of Carbon Nucleophiles to the Strained Bicyclic Acetal 2,7-Dioxabicyclo[2.2.1]heptane

Addition of allyltributylstannane to 2,7-dioxabicyclo[2.2.1]heptane in the presence of TiCl(4) produces 5-allyl-2-(hydroxymethyl)tetrahydrofuran with a trans/cis ratio of 93:7. The trans-selectivity is also observed in additions of various other carbon nucleophiles.
Synthesis of 4-substituted-1,4-dihydropyridines

Abstract A general synthesis of C-4-substituted dihydropyridines is described. The route exploits a standard Hantzsch ester synthesis followed by nucleophilic substitution of a halide with, for example, triethylphosphite. The resulting compounds could have interesting biological properties or may find use as haptens for preparing catalytic antibodies for hydride transfer reactions.
MicroRNAs reinforce repression of PRC2 transcriptional targets independently and through a feed-forward regulatory network

Gene expression can be regulated at multiple levels, but it is not known if and how there is broad coordination between regulation at the transcriptional and post-transcriptional levels. Transcription factors and chromatin regulate gene expression transcriptionally, whereas microRNAs (miRNAs) are small regulatory RNAs that function post-transcriptionally. Systematically identifying the post-transcriptional targets of miRNAs and the mechanism of transcriptional regulation of the same targets can shed light on regulatory networks connecting transcriptional and post-transcriptional control. We used individual-nucleotide resolution UV crosslinking and immunoprecipitation (iCLIP) for the RNA-induced silencing complex (RISC) component AGO2 and global miRNA depletion to identify genes directly targeted by miRNAs. We found that Polycomb repressive complex 2 (PRC2) and its associated histone mark, H3K27me3, is enriched at hundreds of miRNA-repressed genes. We show that these genes are directly repressed by PRC2 and constitute a significant proportion of direct PRC2 targets. For just over half of the genes corepressed by PRC2 and miRNAs, PRC2 promotes their miRNA-mediated repression by increasing expression of the miRNAs that are likely to target them. miRNAs also repress the remainder of the PRC2 target genes, but independently of PRC2. Thus, miRNAs post-transcriptionally reinforce silencing of PRC2-repressed genes that are inefficiently repressed at the level of chromatin, by either forming a feed-forward regulatory network with PRC2 or repressing them independently of PRC2.
The Gas Phase Ion Chemistry of BH2

The reactions of BH2+ with hydrogen and some simple hydrocarbons and hydrides have been studied in the gas phase with a tandem flowing afterglow-selected ion flow tube apparatus. Reaction rate cons...
Crystal Growth of Alkaline Earth Vanadates from Hydroxide Fluxes

Abstract We report the crystal growth and structural characterization of four alkaline earth vanadates synthesized from alkali metal hydroxide flux reactions. The use of molten hydroxides has led to the preparation of the novel hydroxy apatites, A 5 (VO 4 ) 3 (OH) (A = Sr, Ba), isolated from mixed NaOH/A(OH) 2 (A = Sr, Ba) flux reactions contained in sealed silver tubes. Ba 5 (VO 4 ) 3 (OH) and Sr 5 (VO 4 ) 3 (OH) crystallize in the hexagonal space group, P 6 3 / m with a = 10.4589(2) A, c = 7.8476(3) A, V = 743.43(3) A 3 and a = 10.0570(4) A, c = 7.4349(7) A, V = 651.24(7) A 3 , respectively. The crystal structures consist of isolated VO 4 tetrahedra separated by layers of Sr/BaO x polyhedra. In addition, we also report the crystal growth of KBaVO 4 and Ba 3 (VO 4 ) 2 from hydroxide fluxes.
Thermally moderated firefly activity is delayed by precipitation extremes.

The timing of events in the life history of temperate insects is most typically primarily cued by one of two drivers: photoperiod or temperature accumulation over the growing season. However, an in...
Halogen Bond Structure and Dynamics from Molecular Simulations.

Halogen bonding has emerged as an important noncovalent interaction in a myriad of applications, including drug design, supramolecular assembly, and catalysis. The current understanding of the halo...
Nanoscale transfer of angular momentum mediated by the Casimir torque

Casimir interactions play an important role in the dynamics of nanoscale objects. Here, we investigate the noncontact transfer of angular momentum at the nanoscale through the analysis of the Casimir torque acting on a chain of rotating nanoparticles. We show that this interaction, which arises from the vacuum and thermal fluctuations of the electromagnetic field, enables an efficient transfer of angular momentum between the elements of the chain. Working within the framework of fluctuational electrodynamics, we derive analytical expressions for the Casimir torque acting on each nanoparticle in the chain, which we use to study the synchronization of chains with different geometries and to predict unexpected dynamics, including a “rattleback”-like behavior. Our results provide insights into the Casimir torque and how it can be exploited to achieve efficient noncontact transfer of angular momentum at the nanoscale, and therefore have important implications for the control and manipulation of nanomechanical devices. The Casimir torque, a quantum effect caused by the vacuum and thermal fluctuations of the electromagnetic field, is a phenomenon that can cause friction, but is also a manifestation of the optical angular momentum of light. This work describes the transfer of angular momentum between spinning nanoparticles enabled by the Casimir torque and provides calculations for the rotational dynamics of the system.
Modular tissue-specific regulation of doublesex underpins sexually dimorphic development in Drosophila

The ability of a single genome to produce distinct and often dramatically different male and female forms is one of the wonders of animal development. In Drosophila melanogaster, most sexually dimorphic traits are controlled by sex-specific isoforms of the doublesex (dsx) transcription factor, and dsx expression is mostly limited to cells that give rise to sexually dimorphic traits. However, it is unknown how this mosaic of sexually dimorphic and monomorphic organs arises. Here, we characterize the cis-regulatory sequences that control dsx expression in the foreleg, which contains multiple types of sex-specific sensory organs. We find that separate modular enhancers are responsible for dsx expression in each sexually dimorphic organ. Expression of dsx in the sex comb is co-regulated by two enhancers with distinct spatial and temporal specificities that are separated by a genitalia-specific enhancer. The sex comb-specific enhancer from D. willistoni, a species that primitively lacks sex combs, is not active in the foreleg. Thus, the mosaic of sexually dimorphic and monomorphic organs depends on modular regulation of dsx transcription by dedicated cell type-specific enhancers.
Method of automorphic functions for an inverse problem of antiplane elasticity

A nonlinear inverse problem of antiplane elasticity for a multiply connected domain is examined. It is required to determine the profile of $n$ uniformly stressed inclusions when the surrounding infinite body is subjected to antiplane uniform shear at infinity. A method of conformal mappings of circular multiply connected domains is employed. The conformal map is recovered by solving consequently two Riemann-Hilbert problems for piecewise analytic symmetric automorphic functions. For domains associated with the first class Schottky groups a series-form representation of a ($3n-4$) parametric family of conformal maps solving the problem is discovered. Numerical results for two and three uniformly stressed inclusions are reported and discussed.
Spectral clustering for divide-and-conquer graph matching

We present a novel divide-and-conquer bijective graph matching algorithm.The algorithm is fully parallelizable, and scales to match "big data" graphs.We demonstrate the effectiveness of the algorithm by matching DTMRI human connectomes. We present a parallelized bijective graph matching algorithm that leverages seeds and is designed to match very large graphs. Our algorithm combines spectral graph embedding with existing state-of-the-art seeded graph matching procedures. We justify our approach by proving that modestly correlated, large stochastic block model random graphs are correctly matched utilizing very few seeds through our divide-and-conquer procedure. We also demonstrate the effectiveness of our approach in matching very large graphs in simulated and real data examples, showing up to a factor of 8 improvement in runtime with minimal sacrifice in accuracy.
Optimal Experimental Design Using a Consistent Bayesian Approach

We consider the utilization of a computational model to guide the optimal acquisition of experimental data to inform the stochastic description of model input parameters. Our formulation is based o...
Singularities and holonomicity of binomial D-modules

Abstract We study binomial D -modules, which generalize A -hypergeometric systems. We determine explicitly their singular loci and provide three characterizations of their holonomicity. The first of these is an equivalence of holonomicity and L -holonomicity for these systems. The second refines the first by giving more detailed information about the L -characteristic variety of a non-holonomic binomial D -module. The final characterization states that a binomial D -module is holonomic if and only if its corresponding singular locus is proper.
Isospectral graph transformations, spectral equivalence, and global stability of dynamical networks

In this paper we present a general procedure that allows for the reduction or expansion of any network (considered as a weighted graph). This procedure maintains the spectrum of the network's adjacency matrix up to a set of eigenvalues known beforehand from its graph structure. This procedure can be used to establish new equivalence relations on the class of all weighted graphs (networks) where two graphs are equivalent if they can be reduced to the same graph. Additionally, dynamical networks (or any finite dimensional, discrete time dynamical system) can be analysed using isospectral transformations. By doing so we obtain stronger results regarding the global stability (strong synchronization) of dynamical networks when compared with other standard methods.
Distributed probabilistic bisection search using social learning

We present a novel distributed probabilistic bisection algorithm using social learning with application to target localization. Each agent in the network first constructs a query about the target based on its local information and obtains a noisy response. Agents then perform a Bayesian update of their beliefs followed by an averaging of the log beliefs over local neighborhoods. This two stage algorithm consisting of repeated querying and averaging runs until convergence. We derive bounds on the rate of convergence of the beliefs at the correct target location. Numerical simulations show that our method outperforms current state of the art methods.
Gramian-Based Reachability Metrics for Bilinear Networks

This paper studies Gramian-based reachability metrics for bilinear control systems. In the context of complex networks, bilinear systems capture scenarios where an actuator not only can affect the state of a node but also interconnections among nodes. Under the assumption that the input's infinity norm is bounded by some function of the network dynamic matrices, we derive a Gramian-based lower bound on the minimum input energy required to steer the state from the origin to any reachable target state. This result motivates our study of various objects associated with the reachability Gramian to quantify the ease of controllability of the bilinear network: the minimum eigenvalue (worst-case minimum input energy to reach a state), the trace (average minimum input energy to reach a state), and its determinant (volume of the ellipsoid containing the reachable states using control inputs with no more than unit energy). We establish an increasing returns property of the reachability Gramian as a function of the actuators, which, in turn, allows us to derive a general lower bound on the reachability metrics in terms of the aggregate contribution of the individual actuators. We conclude by examining the effect on the worst-case minimum input energy of the addition of bilinear inputs to difficult-to-control linear symmetric networks. We show that the bilinear networks resulting from the addition of either inputs at a finite number of interconnections or at all self loops with weight vanishing with the network scale remain difficult to control. Various examples illustrate our results.
Super-resolution line spectrum estimation with block priors

We address the problem of super-resolution line spectrum estimation of an undersampled signal with block prior information. The component frequencies of the signal are assumed to take arbitrary continuous values in known frequency blocks. We formulate a general semidefinite program to recover these continuous-valued frequencies using positive trigonometric polynomials. The proposed semidefinite program achieves super-resolution frequency recovery by taking advantage of known structures of frequency blocks. Numerical experiments show great performance enhancements using our method.
Noisy transitional flows in imperfect channels

Here, we study noisy transitional flows in imperfect millimetre-scale channels. For probing the flows, we use microcantilever sensors embedded in the channel walls. We perform experiments in two nominally identical channels. The different sets of imperfections in the two channels result in two random flows in which the high-order moments of the near-wall fluctuations differ by orders of magnitude. Surprisingly, however, the lowest-order statistics in both cases appear to be qualitatively similar and can be described by a proposed noisy Landau equation for a slow mode. The noise, regardless of its origin, regularizes the Landau singularity of the relaxation time and makes transitions driven by different noise sources appear similar.
GRADED CHAIN CONDITIONS AND LEAVITT PATH ALGEBRAS OF NO-EXIT GRAPHS

We obtain a complete structural characterization of Cohn–Leavitt algebras over no-exit objects as graded involutive algebras. Corollaries of this result include graph-theoretic conditions characterizing when a Leavitt path algebra is a directed union of (graded) matricial algebras over the underlying field and over the algebra of Laurent polynomials and when the monoid of isomorphism classes of finitely generated projective modules is atomic and cancelative. We introduce the nonunital generalizations of graded analogs of noetherian and artinian rings, graded locally noetherian and graded locally artinian rings, and characterize graded locally noetherian and graded locally artinian Leavitt path algebras without any restriction on the cardinality of the graph. As a consequence, we relax the assumptions of the Abrams–Aranda–Perera–Siles characterization of locally noetherian and locally artinian Leavitt path algebras.
Impacts of network topology on the performance of a Distributed Algorithm Solving Linear Equations

Recently a distributed algorithm has been proposed for multi-agent networks to solve a system of linear algebraic equations, by assuming each agent only knows part of the system and is able to communicate with nearest neighbors to update their local solutions. This paper investigates how the net- work topology impacts exponential convergence of the proposed algorithm. It is found that networks with higher mean degree, smaller diameter, and homogeneous degree distribution tend to achieve faster convergence. Both analytical and numerical results are provided.
Online Transfer Learning in Reinforcement Learning Domains.

This paper proposes an online transfer framework to capture the interaction among agents and shows that current transfer learning in reinforcement learning is a special case of online transfer. Furthermore, this paper re-characterizes existing agents-teaching-agents methods as online transfer and analyze one such teaching method in three ways. First, the convergence of Qlearning and Sarsa with tabular representation with a finite budget is proven. Second, the convergence of Qlearning and Sarsa with linear function approximation is established. Third, the we show the asymptotic performance cannot be hurt through teaching. Additionally, all theoretical results are empirically validated.
Label efficient learning of transferable representations across domains and tasks

We propose a framework that learns a representation transferable across different domains and tasks in a label efficient manner. Our approach battles domain shift with a domain adversarial loss, and generalizes the embedding to novel task using a metric learning-based approach. Our model is simultaneously optimized on labeled source data and unlabeled or sparsely labeled data in the target domain. Our method shows compelling results on novel classes within a new domain even when only a few labeled examples per class are available, outperforming the prevalent fine-tuning approach. In addition, we demonstrate the effectiveness of our framework on the transfer learning task from image object recognition to video action recognition.
Norms of random matrices: Local and global problems

Abstract Can the behavior of a random matrix be improved by modifying a small fraction of its entries? Consider a random matrix A with i.i.d. entries. We show that the operator norm of A can be reduced to the optimal order O ( n ) by zeroing out a small submatrix of A if and only if the entries have zero mean and finite variance. Moreover, we obtain an almost optimal dependence between the size of the removed submatrix and the resulting operator norm. Our approach utilizes the cut norm and Grothendieck–Pietsch factorization for matrices, and it combines the methods developed recently by C. Le and R. Vershynin and by E. Rebrova and K. Tikhomirov.
On cohomology and support varieties for Lie superalgebras

Abstract Support varieties for Lie superalgebras over the complex numbers were introduced in Boe et al. (2010) [BKN1] using the relative cohomology. In this paper we discuss finite generation of the relative cohomology rings for Lie superalgebras, we formulate a definition for subalgebras which detect the cohomology, also discuss realizability of support varieties. In the last section as an application we compute the relative cohomology ring of the Lie superalgebra S ¯ ( n ) relative to the graded zero component S ¯ ( n ) 0 and show that this ring is finitely generated. We also compute support varieties of all simple modules in the category of finite dimensional S ¯ ( n ) -modules which are completely reducible over S ¯ ( n ) 0 .
Fine-Grained Prediction of Syntactic Typology: Discovering Latent Structure with Supervised Learning

We show how to predict the basic word-order facts of a novel language given only a corpus of part-of-speech (POS) sequences. We predict how often direct objects follow their verbs, how often adjectives follow their nouns, and in general the directionalities of all dependency relations. Such typological properties could be helpful in grammar induction. While such a problem is usually regarded as unsupervised learning, our innovation is to treat it as supervised learning, using a large collection of realistic synthetic languages as training data. The supervised learner must identify surface features of a language’s POS sequence (hand-engineered or neural features) that correlate with the language’s deeper structure (latent trees). In the experiment, we show: 1) Given a small set of real languages, it helps to add many synthetic languages to the training data. 2) Our system is robust even when the POS sequences include noise. 3) Our system on this task outperforms a grammar induction baseline by a large margin.
Online Assignment of Heterogeneous Tasks in Crowdsourcing Markets

We investigate the problem of heterogeneous task assignment in crowdsourcing markets from the point of view of the requester, who has a collection of tasks. Workers arrive online one by one, and each declare a set of feasible tasks they can solve, and desired payment for each feasible task. The requester must decide on the fly which task (if any) to assign to the worker, while assigning workers only to feasible tasks. The goal is to maximize the number of assigned tasks with a fixed overall budget. We provide an online algorithm for this problem and prove an upper bound on the competitive ratio of this algorithm against an arbitrary (possibly worst-case) sequence of workers who want small payments relative to the requester’s total budget. We further show an almost matching lower bound on the competitive ratio of any algorithm in this setting. Finally, we propose a different algorithm that achieves an improved competitive ratio in the random permutation model, where the order of arrival of the workers is chosen uniformly at random. Apart from these strong theoretical guarantees, we carry out experiments on simulated data which demonstrates the practical applicability of our algorithms.
Crossmodal Attentive Skill Learner

This paper introduces the Crossmodal Attentive Skill Learner (CASL), integrated with the recently-introduced Asynchronous Advantage Option-Critic (A2OC) architecture [Harb et al., 2017] to enable hierarchical reinforcement learning across multiple sensory inputs. We provide concrete examples where the approach not only improves performance in a single task, but accelerates transfer to new tasks. We demonstrate the attention mechanism anticipates and identifies useful latent features, while filtering irrelevant sensor modalities during execution. We modify the Arcade Learning Environment [Bellemare et al., 2013] to support audio queries, and conduct evaluations of crossmodal learning in the Atari 2600 games H.E.R.O. and Amidar. Finally, building on the recent work of [Babaeizadeh et al., 2017], we open-source a fast hybrid CPU-GPU implementation of CASL.