cssi/SciSciGPT-SciSciNet huggingface dataset:
DETERMINING AN ASSET’S TAX BASIS IN THE ABSENCE OF A MEANINGFUL TRANSFER TAX REGIME

Until recently, in those circumstances where there was a valuation range with respect to a particular asset, executors faced a choice: among estates subject to the estate tax, declaring a high value would increase the estate tax liability; however, due to the Internal Revenue Code’s “basis equal to fair market value” rule applicable at death, declaring a low value would expose heirs to a greater capital gains tax on subsequent asset disposition. Because the estate tax rates were higher and that tax was immediate (as opposed to deferred until a later sale by the heir), executors typically minimized asset values, with the corresponding effect of tax basis diminishment. This commonplace strategy thus negated the possibility that taxpayers might exploit the basis equal to fair market rule. But this is often no longer the case. Through a series of exemption level increases, tax rate reductions, and other reforms, Congress has gutted the nation’s transfer tax system. What remains is a teetering transfer tax system that applies only to a handful of the wealthiest taxpayers. For the rest, the transfer tax system provides no disincentive to executors from assigning the highest defensible valuations to a decedent’s assets, opening the opportunity to capitalize upon the basis equal to fair market value rule. Unfortunately, the I.R.S. lacks the tools and resources to combat this practice. To preserve the integrity of the capital gains tax and the revenue that it produces, Congress must therefore intercede.
Simplified Courts Can't Solve Inequality

State civil courts struggle to handle the volume of cases before them. Litigants in these courts, most of whom are unrepresented, struggle to navigate the courts to solve their problems. This acces...
Chromatin laser imaging reveals abnormal nuclear changes for early cancer detection.

We developed and applied rapid scanning laser-emission microscopy (LEM) to detect abnormal changes in cell nuclei for early diagnosis of cancer and cancer precursors. Regulation of chromatins is essential for genetic development and normal cell functions, while abnormal nuclear changes may lead to many diseases, in particular, cancer. The capability to detect abnormal changes in “apparently normal” tissues at a stage earlier than tumor development is critical for cancer prevention. Here we report using LEM to analyze colonic tissues from mice at-risk for colon cancer (induced by a high-fat diet) by detecting pre-polyp nuclear abnormality. By imaging the lasing emissions from chromatins, we discovered that, despite the absence of observable lesions, polyps, or tumors under stereoscope, high-fat mice exhibited significantly lower lasing thresholds than low-fat mice. The low lasing threshold is, in fact, very similar to that of adenomas and is caused by abnormal cell proliferation and chromatin deregulation that can potentially lead to cancer. Our findings suggest that conventional detection methods, such as colonoscopy followed by histopathology, by itself, may be insufficient to reveal hidden or early tumors under development. We envision that this innovative work will provide new insights into LEM and support existing tools for early tumor detection in clinical diagnosis, and fundamental biological and biomedical research of chromatin changes at the biomolecular level of cancer development.
RT-Gang: Real-Time Gang Scheduling Framework for Safety-Critical Systems

In this paper, we present RT-Gang: a novel real-time gang scheduling framework that enforces a one-gang-at-a-time policy. We find that, in a multicore platform, co-scheduling multiple parallel real-time tasks would require highly pessimistic worst-case execution time (WCET) and schedulability analysis—even when there are enough cores—due to contention in shared hardware resources such as cache and DRAM controller. In RT-Gang, all threads of a parallel real-time task form a real-time gang and the scheduler globally enforces the one-gang-at-a-time scheduling policy to guarantee tight and accurate task WCET. To minimize under-utilization, we integrate a state-of-the-art memory bandwidth throttling framework to allow safe execution of best-effort tasks. Specifically, any idle cores, if exist, are used to schedule best-effort tasks but their maximum memory bandwidth usages are strictly throttled to tightly bound interference to real-time gang tasks. We implement RT-Gang in the Linux kernel and evaluate it on two representative embedded multicore platforms using both synthetic and real-world DNN workloads. The results show that RT-Gang dramatically improves system predictability and the overhead is negligible.
Orthogonal Range Searching in Moderate Dimensions: k-d Trees and Range Trees Strike Back

We revisit the orthogonal range searching problem and the exact $$\ell _\infty $$ nearest neighbor searching problem for a static set of n points when the dimension d is moderately large. We give the first data structure with near linear space that achieves truly sublinear query time when the dimension is any constant multiple of $$\log n$$ . Specifically, the preprocessing time and space are $$O(n^{1+\delta })$$ for any constant $$\delta >0$$ , and the expected query time is $$n^{1-1/O(c\log c)}$$ for $$d=c\log n$$ . The data structure is simple and is based on a new “augmented, randomized, lopsided” variant of k-d trees. It matches (in fact, slightly improves) the performance of previous combinatorial algorithms that work only in the case of offline queries [(Impagliazzo et al. in arXiv:1401.5512 , 2014) and (Chan in Proceedings of the 26th ACM-SIAM Symposium on Discrete Algorithms (SODA), 2015)]. It leads to slightly faster combinatorial algorithms for all-pairs shortest paths in general real-weighted graphs and rectangular Boolean matrix multiplication. In the offline case, we show that the problem can be reduced to the Boolean orthogonal vectors problem and thus admits an $$n^{2-1/O(\log c)}$$ -time non-combinatorial algorithm [Abboud et al. in Proceedings of the 26th Annual ACM-SIAM Symposium on Discrete Algorithms (SODA), 2015]. This reduction is also simple and is based on range trees. Finally, we use a similar approach to obtain a small improvement to Indyk’s data structure (J Comput Syst Sci 63(4):627–638, 2001) for approximate $$\ell _\infty $$ nearest neighbor search when $$d=c\log n$$ .
Pragmatically Informative Text Generation.

We improve the informativeness of models for conditional text generation using techniques from computational pragmatics. These techniques formulate language production as a game between speakers and listeners, in which a speaker should generate output text that a listener can use to correctly identify the original input that the text describes. While such approaches are widely used in cognitive science and grounded language learning, they have received less attention for more standard language generation tasks. We consider two pragmatic modeling methods for text generation: one where pragmatics is imposed by information preservation, and another where pragmatics is imposed by explicit modeling of distractors. We find that these methods improve the performance of strong existing systems for abstractive summarization and generation from structured meaning representations.
Interrelations among expectancies, task values, and perceived costs in undergraduate biology achievement

Abstract Expectancy-value theory highlights the roles of students' expectancies, task values, and perceived costs in their motivation and achievement. While ample research has highlighted the positive associations of expectancy beliefs and task values with academic achievement, research on students' perceived costs is in its infancy. We investigated the temporal interrelations among expectancies, task values and different types of perceived cost, the role of these constructs in biology achievement, and the role of perceived costs as a moderator in the relations of expectancy beliefs to biology achievement. A cross-lagged path analysis of semester-long data from 234 undergraduate biology students pointed to variable relations among expectancies, task values, perceived costs, and biology achievement. For example, while early expectancy beliefs related to later attainment and interest value, early task values and perceived costs did not relate to later expectancy beliefs. Furthermore, early attainment value related to later effort and opportunity cost. Expectancy beliefs and effort and opportunity cost in biology were associated with final biology grade. Finally, effort cost moderated the relations between expectancy beliefs and students' final grades. These findings provide evidence for the dynamic relations among perceived costs, task values, and expectancy beliefs over a semester and point to the interplay between expectancies and perceived costs in their relation to academic achievement in science.
Planar N -body central configurations with a homogeneous potential

Central configurations give rise to self-similar solutions to the Newtonian N-body problem and play important roles in understanding its complicated dynamics. Even the simple question of whether or not there are finitely many planar central configurations for N positive masses remains unsolved in most cases. Considering central configurations as critical points of a function f, we explicitly compute the eigenvalues of the Hessian of f for all N for the point vortex potential for the regular polygon with equal masses. For homogeneous potentials including the Newtonian case, we compute bounds on the eigenvalues for the regular polygon with equal masses and give estimates on where bifurcations occur. These eigenvalue computations imply results on the Morse indices of f for the regular polygon. Explicit formulae for the eigenvalues of the Hessian are also given for all central configurations of the equal-mass four-body problem with a homogeneous potential. Classic results on collinear central configurations are also generalized to the homogeneous potential case. Numerical results, conjectures, and suggestions for the future work in the context of a homogeneous potential are given.
Controllable Paraphrase Generation with a Syntactic Exemplar

Prior work on controllable text generation usually assumes that the controlled attribute can take on one of a small set of values known a priori. In this work, we propose a novel task, where the syntax of a generated sentence is controlled rather by a sentential exemplar. To evaluate quantitatively with standard metrics, we create a novel dataset with human annotations. We also develop a variational model with a neural module specifically designed for capturing syntactic knowledge and several multitask training objectives to promote disentangled representation learning. Empirically, the proposed model is observed to achieve improvements over baselines and learn to capture desirable characteristics.
Drunken driving and riding with a drunken driver: adolescent types at higher risk

The leading cause of death of adolescents in developed countries is injury. Alcohol is a major contributor to adolescent injury. Most of the injury deaths in youth are caused by traffic crashes. Dr...
A cool accretion disk around the Galactic Centre black hole.

There is a supermassive black hole of mass 4 × 10^6 solar masses at the centre of the Milky Way. A large reservoir of hot (10^7 kelvin) and cooler (10^2 to 10^4 kelvin) gas surrounds it within a few parsecs. Although constraints on the amount of hot gas in the accretion zone of the black hole—that is, within 10^5 Schwarzschild radii (0.04 parsecs)—have been provided by X-ray observations, the mass in cooler gas has been unconstrained. One possible way this cooler gas could be detected is by its emission in hydrogen recombination spectral lines. Here we report imaging of a 10^4-kelvin ionized gas disk within 2 × 10^4 Schwarzschild radii, using the 1.3-millimetre recombination line H30α. This emission line is double-peaked, with full velocity linewidth of about 2,200 kilometres per second. The emission is centred on the radio source Sagittarius A*, but the redshifted side is displaced 0.11 arcsec (0.004 parsecs at a distance of 8 kiloparsecs) to the northeast and the blueshifted side is displaced a similar distance to the southwest. We interpret these observations in terms of a rotating disk of mass 10^(−5) to 10^(−4) solar masses and mean hydrogen density of about 10^5 to 10^6 per cubic centimetre, with the values being sensitive to the assumed geometry. The emission is stronger than expected, given the upper limit on the strength of the Brγ spectral line of hydrogen. We suggest that the H30α transition is enhanced by maser emission.
Synergistic Geometrical and Electronic Features in the Intermetallic Phases Ca2AgM2, Ca2MgM2, and Ca2GaM2 (M = Pd, Pt)

Six new analogous phases, Ca2AgM2, Ca2MgM2, and Ca2M2Ga (M = Pd, Pt), were rationally prepared by direct combination of the respective elements at high temperature, allowing us to clarify the factors controlling the structural selection between the orthorhombic W2CoB2-type structure (Immm) and its distorted monoclinic Gd2AlGe2-type derivative (C2/c), as well as to investigate the mechanism and the extent of the electronic flexibility of the W2CoB2-type structure. All crystal structures were refined from single-crystal X-ray diffraction data. Two pairs of compounds Ca2AgM2 (5 ve/f.u) and Ca2MgM2 (6 ve/f.u) adopt the orthorhombic W2CoB2 type, whereas the pair of Ga analogues Ca2M2Ga (7 ve/fu) crystallize in the monoclinic Gd2AlGe2- or Ca2Ir2Si-type structure, confirming the valence electron count (vec) as the dominant factor controlling the structural selection in this series. The stability factors and chemical bonding features behind the similarities and differences of these closely related structures were theoretically investigated using first-principles density functional calculations. They provide additional evidences of the decisive influence of the vec as well as the electronegativity differences between constituent elements, on the structural trends. In addition, the cooperative roles of the geometrical and electronic flexibility associated with the inherent anisotropy of the orthorhombic symmetry of the W2CoB2 type are emphasized.
Structure, properties, and reactivity of solid fuels

Solid-fuel combustion is one of man's oldest technologies, but it continues to play an important societal role as we approach the third millennium. Various economic and environmental factors are leading to a diversification in fuels—the practitioner can no longer restrict his interest to the combustion behavior of one or several regional coals but must consider a wide variety of potential solid fuels, including biomass, solid wastes, and internationally traded coals. This paper begins with a brief discussion of the technological issues that define research needs in solid-fuel combustion and then presents a brief overview of the fuels themselves and their important fundamental properties. A central theme in the paper is the remarkable variation in the structure, reactivity, and properties of chars from the diverse array of practical solid fuels. The density, oxidation reactivity, and physical adsorption capacity are identified as key char properties, as they strongly influence the degree of carbon burnout in pulverized fuel combustion, the volume of the solid waste produced, and the behavior of the resulting fly ash in post-combustion utilization schemes, most notably concrete. Many char properties are shown to depend on char crystalline structure, or nanostructure, which varies from disordered to ordered as a function of precursor chemistry and char formation conditions. Another theme in the paper is the possibility of predicting combustion rates and burnout times of different solid fuels in a common combustion environment. The paper discusses predictive schemes, which are based on hybrid correlative and mechanistic approaches, in which intraparticle and boundary-layer transport processes are described mechanistically, while surface reactivity and particle density are obtained from empirical correlations with parent fuel properties. Although these complex solids are intrinsically more difficult to describe and model than are gaseous and liquid fuels, there is great potential for developing more fundamental descriptions of the char formation and reaction processes.
SYNTHESIS OF STIPIAMIDE AND A NEW MULTIDRUG RESISTANCE REVERSAL AGENT, 6,7-DEHYDROSTIPIAMIDE

Stipiamide,1 a new member of a growing class of insecticidal polyene antibiotics,2 has recently been patented (under the name phenalamid A1) for its anti-HIV and antifungal activity.3 Most remarkably, this compound has also been shown to reverse P-glycoprotein-mediated multidrug resistance (MDR), a condition common to many cancer cell lines.4 The ability to potentiate the cytotoxicity of antitumor drugs toward drug resistant cells has been demonstrated by verapamil, cyclosporinA,5 GF120918,6 and more recently hapalosin.7 However, the clinical performance of MDR reversal agents has not been adequate, making the identification of new agents of great importance.8 To this end a flexible route to stipiamide was pursued to make possible the synthesis of new MDR reversal agents. In spite of their wide range of activity, a synthetic route to the polyene antibiotics has not been reported.9 Herein, we report the first total synthesis of stipiamide and the design and synthesis of 6,7-dehydrostipiamide (a new non-natural compound), now shown to potently reverse MDR in human MCF-7 adriamycin resistant breast cancer cells (MCF-7adrR).10 Also, 6,7-dehydrostipiamide is remarkably less toxic relative to stipiamide.
Maternal loading of a small heat shock protein increases embryo thermal tolerance in Drosophila melanogaster.

Maternal investment is likely to have direct effects on offspring survival. In oviparous animals whose embryos are exposed to the external environment, maternal provisioning of molecular factors like mRNAs and proteins may help embryos cope with sudden changes in the environment. Here, we sought to modify the maternal mRNA contribution to offspring embryos and test for maternal effects on acute thermal tolerance in early embryos of Drosophila melanogaster We drove in vivo overexpression of a small heat shock protein gene (Hsp23) in female ovaries and measured the effects of acute thermal stress on offspring embryonic survival and larval development. We report that overexpression of the Hsp23 gene in female ovaries produced offspring embryos with increased thermal tolerance. We also found that brief heat stress in the early embryonic stage (0-1 h old) caused decreased larval performance later in life (5-10 days old), as indexed by pupation height. Maternal overexpression of Hsp23 protected embryos against this heat-induced defect in larval performance. Our data demonstrate that transient products of single genes have large and lasting effects on whole-organism environmental tolerance. Further, our results suggest that maternal effects have a profound impact on offspring survival in the context of thermal variability.
Palladium-Catalyzed Conjugate Allylation Reactions of α,β-Unsaturated N-Acylpyrroles

Conjugate allylation reactions of α,β-unsaturated N-acylpyrroles using allylboronic ester are catalyzed by a palladium complex that is ligated by a bidentate N-heterocyclic carbene. A variety of functional groups are tolerated, and substrates functionalized with electron-withdrawing groups react to afford the highest yields of products. Regioselectivity for 1,4-allylation over 1,2-allylation is demonstrated, and mechanistic experiments are consistent with formation of nucleophilic allylpalladium intermediates.
Comparison of amine additives most effective in the new methyltrioxorhenium-catalyzed epoxidation process

Abstract Three different heterocyclic amine additives, pyridine, 3-cyanopyridine and pyrazole are compared in the methyltrioxorhenium (MTO) catalyzed epoxidation of olefins using aqueous hydrogen peroxide.
The Impact of Chromatin Dynamics on Cas9-Mediated Genome Editing in Human Cells

In order to efficiently edit eukaryotic genomes, it is critical to test the impact of chromatin dynamics on CRISPR/Cas9 function and develop strategies to adapt the system to eukaryotic contexts. So far, research has extensively characterized the relationship between the CRISPR endonuclease Cas9 and the composition of the RNA–DNA duplex that mediates the system’s precision. Evidence suggests that chromatin modifications and DNA packaging can block eukaryotic genome editing by custom-built DNA endonucleases like Cas9; however, the underlying mechanism of Cas9 inhibition is unclear. Here, we demonstrate that closed, gene-silencing-associated chromatin is a mechanism for the interference of Cas9-mediated DNA editing. Our assays use a transgenic cell line with a drug-inducible switch to control chromatin states (open and closed) at a single genomic locus. We show that closed chromatin inhibits binding and editing at specific target sites and that artificial reversal of the silenced state restores editing effi...
Rapid Fluorous Stille Coupling Reactions Conducted under Microwave Irradiation

Palladium-catalyzed fluorous Stille cross-coupling reactions with organic halides or triflates require only 90−120 s for completion when conducted under microwave irradiation. Comparable thermal reactions require about 1 day. Fourteen different coupling products were synthesized and isolated in good yields after three-phase extraction (FC-84, dichloromethane, water) and chromatography. The examples extend the scope of the fluorous Stille coupling with respect to both the tin and halide/triflate components. Applications in parallel synthesis are suggested.
Prediction of Subgenome Additive and Interaction Effects in Allohexaploid Wheat

Whole genome duplications have played an important role in the evolution of angiosperms. These events often occur through hybridization between closely related species, resulting in an allopolyploid with multiple subgenomes. With the availability of affordable genotyping and a reference genome to locate markers, breeders of allopolyploids now have the opportunity to manipulate subgenomes independently. This also presents a unique opportunity to investigate epistatic interactions between homeologous orthologs across subgenomes. We present a statistical framework for partitioning genetic variance to the subgenomes of an allopolyploid, predicting breeding values for each subgenome, and determining the importance of inter-genomic epistasis. We demonstrate using an allohexaploid wheat breeding population evaluated in Ithaca, NY and an important wheat dataset from CIMMYT previously shown to demonstrate non-additive genetic variance. Subgenome covariance matrices were constructed and used to calculate subgenome interaction covariance matrices for variance component estimation and genomic prediction. We propose a method to extract population structure from all subgenomes at once before covariances are calculated to reduce collinearity between subgenome estimates. Variance parameter estimation was shown to be reliable for additive subgenome effects, but was less reliable for subgenome interaction components. Predictive ability was equivalent to current genomic prediction methods. Including only inter-genomic interactions resulted in the same increase in accuracy as modeling all pairwise marker interactions. Thus, we provide a new tool for breeders of allopolyploid crops to characterize the genetic architecture of existing populations, determine breeding goals, and develop new strategies for selection of additive effects and fixation of inter-genomic epistasis.
Size‐Independent Susceptibility to Transport in Aeolian Saltation

Natural wind-eroded soils contain a mixture of particle sizes. However, models for aeolian saltation are typically derived for sediment bed surfaces containing only a single particle size. To nonetheless treat natural mixed beds, models for saltation and associated dust aerosol emission have typically simplified aeolian transport either as a series of non-interacting single particle size beds or as a bed containing only the median or mean particle size. Here, we test these common assumptions underpinning aeolian transport models using measurements of size-resolved saltation fluxes at three natural field sites. We find that a wide range of sand size classes experience "equal susceptibility" to saltation at a single common threshold wind shear stress, contrary to the "selective susceptibility" expected for treatment of a mixed bed as multiple single particle size beds. Our observation of equal susceptibility refutes the common simplification of saltation as a series of non-interacting single particle sizes. Sand transport and dust emission models that use this incorrect assumption can be both simplified and improved by instead using a single particle size representative of the mixed bed.
New developments in the chemistry of organoaluminum and organogallium hydrides

Abstract A survey of our recent work on organoaluminum and organogallium hydrides is presented. Three types of ligand system have been employed for the stabilization of monomeric aluminum and gallium mono- and dihydrides. The “two-armed” 2,6-bis (dimethylaminomethyl) phenyl ligand is effective when intramolecular bis(base) stabilization is necessary; its use has permitted the isolation of the first examples of monomeric aluminum and gallium dihydrates. The use of the corresponding “one-armed” 2-(dimethylaminomethyl) phenyl ligand resulted in the formation of gallium mono- and dihydride monomers and an aluminum dihydride dimer. The first base-free aluminum and gallium monohydrides and gallium dihydride have been stabilized by employing the bulky 2, 4, 6, -tris(t-butyl) phenyl ligand.
Synthesis and structure-activity relationships of (R)-1-alkyl-3-[2-(2-amino)phenethyl]-5-(2-fluorophenyl)-6-methyluracils as human GnRH receptor antagonists

Abstract The synthesis of a series of (R)-1-alkyl-3-[2-(2-amino)phenethyl]-5-(2-fluorophenyl)-6-methyluracils is discussed. SAR around N-1 of the uracil was explored, which led to the discovery that an electron-deficient 2,6-disubstituted benzyl group is required for optimal receptor binding. The best compound from the series had binding affinity of 0.7 nM (Ki) for the human GnRH receptor, which was 8-fold better than the 2,6-difluorobenzyl analog.
Experimental confirmation of the standard magnetorotational instability mechanism with a spring-mass analogue

The magnetorotational instability (MRI) has long been considered a plausibly ubiquitous mechanism to destabilize otherwise stable Keplerian flows to support radially outward transport of angular momentum. Such an efficient transport process would allow fast accretion in astrophysical objects such as stars and black holes to release copious kinetic energy that powers many of the most luminous sources in the universe. But the standard MRI under a purely vertical magnetic field has heretofore never been directly measured despite numerous efforts over more than a decade. Here we report an unambiguous laboratory demonstration of the spring-mass analogue to the standard MRI by comparing motion of a spring-tethered ball within different rotating flows. The experiment corroborates the theory: efficient outward angular momentum transport manifests only for cases with a weak spring in quasi-Keperian flow. Our experimental method accomplishes this in a new way, thereby connecting solid and fluid mechanics to plasma astrophysics. Magnetorotational Instability (MRI) has long been considered a possible mechanism to transport angular momentum allowing fast accretion in astrophysical objects, but its standard form with a vertical magnetic field has never been experimentally verified. The authors present an experimental demonstration of a spring-mass analogue of the standard MRI using water as working fluid and a spring to mimic the action of magnetic fields.
N-alkenyl indoles as useful intermediates for alkaloid synthesis.

A mild cross-coupling reaction to access several N-alkenyl-substituted indoles has been developed. The coupling procedure involves treating a NH-indole with various alkenyl bromides using a combination of 10 mol % of copper(I) iodide and 20 mol % of ethylenediamine as the catalyst in dioxane at 110 °C in the presence of K3PO4 as the base. When treated with acid, these unique enamines produce a dimeric product derived from a preferred protonation reaction at the enamine π-bond. A cationic cyclization reaction of the readily available 2-(2-(1H-indol-1-yl)allyl)cyclopentanol was utilized to construct tetracyclic indole derivatives with a quaternary stereocenter attached to the C2-position of the indole ring. An alternative strategy for selective functionalization at the C2-position of a N-alkenyl-substituted indole derivative that was also studied involves a radical cyclization of a xanthate derivative. The work described provides an attractive route to the tetracyclic core of some vinca alkaloids, including...
Synthesis and structural studies of hydrophilic mesocyclic trithioethers

The functionalized mesocyclic trithioethers, 1,4,7-trithiacyclodecane-9,9-dimethanol (10S3-diMeOH), 9 -methyl-1, 4, 7 - trithiacyclodecane - 9 -carboxylic acid (Me-10S3-acid), 1,4,7-trithiacycloundecane-9,10-diol (dihydroxy-11S3), 1,5,9-trithiacyclododecane-3,3-dimethanol (12S3-diMeOH), 3-methyl-1,5,9-trithiacyclododecane-3-carboxylic acid (Me-12S3-acid), and 1 , 5 , 9 - trit hiacyclo tride cane -11 , 12 - diol ( dihydroxy - 13S3), have been synthesized using the cesium dithiolate technique. The single-crystal X-ray structure has been determined for 3-methyl-1,5,9-trithiacyclododecane-3-carboxylic acid. The compound crystallizes in the monoclinic space group P21/n, with a = 9.513(2) A, b = 5.706(1) A, c = 25.70(1) A, β = 96.50(1)°, Z = 4, and R = 0.075. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:123–128, 1998
Direct Nucleophilic Acylation of Nitroalkenes Promoted by a Fluoride Anion/Thiourea Combination

The direct nucleophilic acylation of nitroalkenes is reported utilizing a fluoride-initiated rearrangement of protected thiazolium carbinols. The key combination of fluoride anion and thiourea accesses carbonyl anion reactivity without the use of amine or amide bases typically employed in the generation of these Umpolung nucleophiles. The mild reaction conditions used to generate the reactive carbonyl anion species in situ allow for conjugate additions in good yield to sensitive nitroalkene electrophiles. The process is tolerant of a variety of thiazolium carbinols and nitroalkene substrates and can be rendered enantioselective and diastereoselective by the addition of a chiral thiourea derived from quinine.
α-Agostic Interactions and Olefin Insertion in Metallocene Polymerization Catalysts

In the 40 years since the discovery of transition metal catalysts for olefin polymerization by Ziegler and Natta a substantial amount of research has been directed toward understanding the basic mechanistic steps of this important industrial process. Attention has focused in particular on the process of monomer enchainment, which is generally agreed to occur through olefin coordination followed by insertion into a metal-carbon bond. Four general mechanistic proposals for the nature of this insertion have emerged (Scheme 1). The first is alkyl migration to the coordinated olefin and is known as the Cossee-Arlman mechanism. The second model, proposed by Rooney and Green, involves an oxidative 1,2-hydrogen shift from the R-carbon of the polymer chain, generating a metal-alkylidene hydride. This species then reacts with an olefin to generate a metallacyclobutane, and reductive elimination completes the propagation sequence. Somewhat intermediate to the first two proposals is a mechanism proposed by Green, Rooney, and Brookhart where a hydrogen atom on the R-carbon of the growing polymer chain interacts with the metal center throughout the catalytic cycle. This three-center, two-electron covalent bond, termed an “agostic interaction”, occurs when the hydrogen atom is simultaneously bonded to both a carbon and a metal atom. The fourth mechanistic possibility is olefin insertion where an R-hydrogen interacts with the metal center only during the transition state of the C-C bond forming step. This mechanism is a hybrid of the Cossee-Arlman and modified Green-Rooney mechanisms.
Rearrangement of allylic cyclic sulfites to allylic sultones

Abstract Rearrangement of allylic cyclic sulfites 2 to allylic sultones 8 upon treatment with boron triflouride etherate is described.
The synthesis of symmetrical (2-indolyl)ethynes and reduced congeners via palladium-catalyzed couplings of 2-bromoindole precursors

Starting from a series of 2-bromo-1-methylindole precursors (1b-e) activated in the 3-position with aldehyde, ester, or amide functionality, two approaches have been developed toward the synthesis of 2,2′-bis(indolyl)ethynes and reduced congeners via palladium(0)- or palladium(II)-catalyzed couplings. The first approach utilized Sonogashira coupling of (trimethylsilyl)acetylene to introduce the two-carbon linker followed by desilylation and further coupling with starting 2-bromoindole. A second shorter and more efficient route engaged the starting 2-bromoindole in a double Stille coupling with bis(tributylstannyl) acetylene or (E)-1,2-bis(tributylstannyl)ethylene to provide desired homodimers in one step. Subsequent transformations of dimeric intermediates led to target acids 7a-c and derived amides 8a-c and 9. When tested against a panel of tyrosine kinases, each target compound was found to be inactive.
Habitat preference of an herbivore shapes the habitat distribution of its host plant.

Plant distributions can be limited by habitat‐biased herbivory, but the proximate causes of such biases are rarely known. Distinguishing plant‐centric from herbivore‐centric mechanisms driving differential herbivory between habitats is difficult without experimental manipulation of both plants and herbivores. Here, we tested alternative hypotheses driving habitat‐biased herbivory in bittercress (Cardamine cordifolia), which is more abundant under the shade of shrubs and trees (shade) than in nearby meadows (sun) where herbivory is intense from the specialist fly Scaptomyza nigrita. This system has served as a textbook example of habitat‐biased herbivory driving a plant's distribution across an ecotone, but the proximate mechanisms underlying differential herbivory are still unclear. First, we found that higher S. nigrita herbivory in sun habitats contrasts sharply with their preference to attack plants from shade habitats in laboratory‐choice experiments. Second, S. nigrita strongly preferred leaves in simulated sun over simulated shade habitats, regardless of plant source habitat. Thus, herbivore preference for brighter, warmer habitats overrides their preference for more palatable shade plants. This promotes the sun‐biased herbivore pressure that drives the distribution of bittercress into shade habitats.
Intramolecular photocycloaddition of cyclic thioimides as a method for heterocyclic synthesis.

Cyclic thioimides undergo photocycloaddition with tethered π-bonds in a regiospecific manner to afford spirocyclic amidothietanes. These highly strained multicycles undergo a subsequent ring opening reaction to furnish novel fused pyrrolizinones.
Exploring community structure in biological networks with random graphs

Background: Community structure is ubiquitous in biological networks. There has been an increased interest in unraveling the community structure of biological systems as it may provide important insights into a system’s functional components and the impact of local structures on dynamics at a global scale. Choosing an appropriate community detection algorithm to identify the community structure in an empirical network can be difficult, however, as the many algorithms available are based on a variety of cost functions and are difficult to validate. Even when community structure is identified in an empirical system, disentangling the effect of community structure from other network properties such as clustering coefficient and assortativity can be a challenge. Results: Here, we develop a generative model to produce undirected, simple, connected graphs with a specified degrees and pattern of communities, while maintaining a graph structure that is as random as possible. Additionally, we demonstrate two important applications of our model: (a) to generate networks that can be used to benchmark existing and new algorithms for detecting communities in biological networks; and (b) to generate null models to serve as random controls when investigating the impact of complex network features beyond the byproduct of degree and modularity in empirical biological networks. Conclusion: Our model allows for the systematic study of the presence of community structure and its impact on network function and dynamics. This process is a crucial step in unraveling the functional consequences of the structural properties of biological systems and uncovering the mechanisms that drive these systems.
Asymmetric hydrosilylation of ketones catalyzed by ruthenium complexes with chiral tridentate ligands

Abstract A new chiral tridentate ligand containing two phosphines and one pyridine is effective for Ru-catalyzed asymmetric hydrosilylation of simple ketones (47–66% ee ). Ruthenium complexes with either chiral tridentate nitrogen ligands or chiral bidentate phosphorus ligands are either inactive or non-selective for asymmetric hydrosilylation. This work has set a foundation for the asymmetric catalytic reactions based on chiral mixed PN tridentate ligands.
High Accuracy Base Calls in Nanopore Sequencing

Nanopore sequencing has introduced the ability to sequence long stretches of DNA, enabling the resolution of repeating segments, or paired SNPs across long stretches of DNA. Unfortunately, significant error rates >15%, introduced through systematic and random noise inhibit downstream analysis. We propose a novel method, using unsupervised learning, to correct biologically amplified reads before downstream analysis proceeds. We also demonstrate that our method has performance comparable to existing techniques without limiting the detection of repeats, or the length of the input sequence.
Evaluating strategies for reversing CRISPR-Cas9 gene drives

A gene drive biases inheritance of a gene so that it increases in frequency within a population even when the gene confers no fitness benefit. There has been renewed interest in environmental releases of engineered gene drives due to recent proof of principle experiments with the CRISPR-Cas9 system as a drive mechanism. Release of modified organisms, however, is controversial, especially when the drive mechanism could theoretically alter all individuals of a species. Thus, it is desirable to have countermeasures to reverse a drive if a problem arises. Several genetic mechanisms for limiting or eliminating gene drives have been proposed and/or developed, including synthetic resistance, reversal drives, and immunizing reversal drives. While predictions about efficacy of these mechanisms have been optimistic, we lack detailed analyses of their expected dynamics. We develop a discrete time model for population genetics of a drive and proposed genetic countermeasures. Efficacy of drive reversal varies between countermeasures. For some parameter values, the model predicts unexpected behavior including polymorphic equilibria and oscillatory dynamics. The timing and number of released individuals containing a genetic countermeasure can substantially impact outcomes. The choice among countermeasures by researchers and regulators will depend on specific goals and population parameters of target populations.
The Data Processing Pipeline and Science Analysis of the Sun Radio Interferometer Space Experiment

The Earths Ionosphere limits radio measurements on its surface, blocking out any radiation below 10 MHz. Valuable insight into many astrophysical processes could be gained by having a radio interferometer in space to image the low frequency window, which has never been achieved. One application for such a system is observing type II bursts that track solar energetic particle acceleration occurring at Coronal Mass Ejection (CME)-driven shocks. In this work we create a data processing pipeline for the pathfinder mission SunRISE, a 6 CubeSat interferometer to circle the Earth in a GEO graveyard orbit, and evaluate its performance in localizing type II bursts with a simulated CME. Traditional radio astronomy software is hard coded to assume an Earth based array. To circumvent this, we manually calculate the antenna separations and insert them along with the simulated visibilities into a CASA MS file for analysis. We model the response of different array configurations over the 25 hour orbit, combining an ephemeris for the Sun with simulated recovered positions of spacecraft using GPS localization to get the array geometry into the correct frame for processing. We include realistic thermal noise dominated by the galactic background at these low frequencies, as well as new sources of phase noise from positional uncertainty of each spacecraft. To create realistic virtual type II input data, we employ a 2-temperature MHD simulation of the May 13th 2005 CME event, and superimpose realistic radio emission models on the CME-driven shock front, and propagate the signal through the simulated array. Data cuts based on different plasma parameter thresholds (e.g. de Hoffman-Teller velocity and angle between shock normal and the upstream magnetic field) are tested to get the best match to the true recorded emission. We test simulated trajectories of SunRISE and image what the array recovers, comparing it to the virtual input, finding that SunRISE can resolve the source of type II emission to within its prescribed goal of 1/3 the CME width more than 99% of the time with 5 or 6 spacecraft, and 97.5% of the time with 4 spacecraft.
Solvent-free tetrahydropyranylation (THP) of alcohols and phenols and their regeneration by catalytic aluminum chloride hexahydrate

Abstract A catalytic amount of aluminum chloride hexahydrate enables solvent-free tetrahydropyranylation (THP) of alcohols and phenols at moderate temperatures. A simple addition of methanol helps to regenerate the corresponding alcohols and phenols, thus rendering these protection and deprotection sequences as very efficient transformations at high substrate to catalyst ratios.
Active membrane conductances and morphology of a collision detection neuron broaden its impedance profile and improve discrimination of input synchrony.

Neuronal filtering and integration of synaptic input patterns depend on the electrochemical properties of dendrites. We used an identified collision detection neuron in grasshoppers to examine how ...
The Tomato Translational Landscape Revealed by Transcriptome Assembly and Ribosome Profiling.

Recent applications of translational control in Arabidopsis (Arabidopsis thaliana) highlight the potential power of manipulating mRNA translation for crop improvement. However, to what extent translational regulation is conserved between Arabidopsis and other species is largely unknown, and the translatome of most crops remains poorly studied. Here, we combined de novo transcriptome assembly and ribosome profiling to study global mRNA translation in tomato (Solanum lycopersicum) roots. Exploiting features corresponding to active translation, we discovered widespread unannotated translation events, including 1,329 upstream open reading frames (uORFs) within the 5′ untranslated regions of annotated coding genes and 354 small ORFs (sORFs) among unannotated transcripts. uORFs may repress translation of their downstream main ORFs, whereas sORFs may encode signaling peptides. Besides evolutionarily conserved sORFs, we uncovered 96 Solanaceae-specific sORFs, revealing the importance of studying translatomes directly in crops. Proteomic analysis confirmed that some of the unannotated ORFs generate stable proteins in planta. In addition to defining the translatome, our results reveal the global regulation by uORFs and microRNAs. Despite diverging over 100 million years ago, many translational features are well conserved between Arabidopsis and tomato. Thus, our approach provides a high-throughput method to discover unannotated ORFs, elucidates evolutionarily conserved and unique translational features, and identifies regulatory mechanisms hidden in a crop genome.
A framework for time-consistent, risk-averse model predictive control: Theory and algorithms

In this paper we present a framework for risk-averse model predictive control (MPC) of linear systems affected by multiplicative uncertainty. Our key innovation is to consider time-consistent, dynamic risk metrics as objective functions to be minimized. This framework is axiomatically justified in terms of time-consistency of risk preferences, is amenable to dynamic optimization, and is unifying in the sense that it captures a full range of risk assessments from risk-neutral to worst case. Within this framework, we propose and analyze an online risk-averse MPC algorithm that is provably stabilizing. Furthermore, by exploiting the dual representation of time-consistent, dynamic risk metrics, we cast the computation of the MPC control law as a convex optimization problem amenable to implementation on embedded systems. Simulation results are presented and discussed.
Nucleus Accumbens Fast-Spiking Interneurons Constrain Impulsive Action.

Abstract Background The nucleus accumbens (NAc) controls multiple facets of impulsivity but is a heterogeneous brain region with diverse microcircuitry. Prior literature links impulsive behavior in rodents to gamma-aminobutyric acid signaling in the NAc. Here, we studied the regulation of impulsive behavior by fast-spiking interneurons (FSIs), a strong source of gamma-aminobutyric acid–mediated synaptic inhibition in the NAc. Methods Male and female transgenic mice expressing Cre recombinase in FSIs allowed us to identify these sparsely distributed cells in the NAc. We used a 5-choice serial reaction time task to measure both impulsive action and sustained attention. During the 5-choice serial reaction time task, we monitored FSI activity with fiber photometry calcium imaging and manipulated FSI activity with chemogenetic and optogenetic methodology. We used electrophysiology, optogenetics, and fluorescent in situ hybridization to confirm these methods were robust and specific to FSIs. Results In mice performing the 5-choice serial reaction time task, NAc FSIs showed sustained activity on trials ending with correct responses, but FSI activity declined over time on trials ending with premature responses. The number of premature responses increased significantly after sustained chemogenetic inhibition or temporally delimited optogenetic inhibition of NAc FSIs, without any changes in response latencies or general locomotor activity. Conclusions These experiments provide strong evidence that NAc FSIs constrain impulsive actions, most likely through gamma-aminobutyric acid–mediated synaptic inhibition of medium spiny projection neurons. Our findings may provide insight into the pathophysiology of disorders associated with impulsivity and may inform the development of circuit-based therapeutic interventions.
Bloch-Floquet Waves in Optical Ring Resonators

We develop a general theory of the modal coupling of degenerate resonances in optical ring resonators based on Bloch-Floquet theory. This theory can predict the splitting associated with this coupling in all the ring resonances. © 2019 The Author(s)