cssi/SciSciGPT-SciSciNet huggingface dataset:
mRNP architecture in translating and stress conditions reveals an ordered pathway of mRNP compaction

Stress granules (SGs) are transient membraneless organelles of nontranslating mRNA–protein complexes (mRNPs) that form during stress. In this study, we used multiple single-molecule FISH probes for particular mRNAs to examine their SG recruitment and spatial organization. Ribosome runoff is required for SG entry, as long open reading frame (ORF) mRNAs are delayed in SG accumulation, indicating that the SG transcriptome changes over time. Moreover, mRNAs are ∼ 20× compacted from an expected linear length when translating and compact ∼ 2-fold further in a stepwise manner beginning at the 5′ end during ribosome runoff. Surprisingly, the 5′ and 3′ ends of the examined mRNAs were separated when translating, but in nontranslating conditions the ends of long ORF mRNAs become close, suggesting that the closed-loop model of mRNPs preferentially forms on nontranslating mRNAs. Compaction of ribosome-free mRNAs is ATP independent, consistent with compaction occurring through RNA structure formation. These results suggest that translation inhibition triggers an mRNP reorganization that brings ends closer, which has implications for the regulation of mRNA stability and translation by 3′ UTR elements and the poly(A) tail.
Stakeholder Tokens: a constructive method for value sensitive design stakeholder analysis

A robust stakeholder analysis requires extensive conceptual and empirical work. Yet it is often unclear how to effectively do so. This paper introduces a new method—the Stakeholder Tokens—for designers to elicit a more inclusive set of stakeholders and gain better understanding of stakeholder interrelationships and dynamics. Stakeholder Tokens present a playful hands-on design approach to support value sensitive design stakeholder analyses by employing a style of role play.
Brillouin flow in recirculating planar magnetron

We examine the Brillouin flow in the conventional magnetron, inverted magnetron, and planar magnetron, with respect to the equilibrium, stability, and operating conditions. This renewed interest was prompted by our recent invention of the recirculating planar magnetron (RPM), where rapid startup utilizes the negative mass instability in the inverted magnetron configuration. Given that Brillouin flow is the most likely state in a crossed-field gap, and that various embodiments of the RPM consist of the conventional, inverted, and planar magnetron, it is necessary to study equilibrium, stability, and operating conditions at the same footing. To study startup, we solve the eigenvalue problem that governs the stability of Brillouin flow, including the effects of the resonant cavities that form the slow wave structures.
Learning Single-Image Depth From Videos Using Quality Assessment Networks

Depth estimation from a single image in the wild remains a challenging problem. One main obstacle is the lack of high-quality training data for images in the wild. In this paper we propose a method to automatically generate such data through Structure-from-Motion (SfM) on Internet videos. The core of this method is a Quality Assessment Network that identifies high-quality reconstructions obtained from SfM. Using this method, we collect single-view depth training data from a large number of YouTube videos and construct a new dataset called YouTube3D. Experiments show that YouTube3D is useful in training depth estimation networks and advances the state of the art of single-view depth estimation in the wild.
Lexicosyntactic inference in neural models.

We investigate neural models’ ability to capture lexicosyntactic inferences: inferences triggered by the interaction of lexical and syntactic information. We take the task of event factuality prediction as a case study and build a factuality judgment dataset for all English clause-embedding verbs in various syntactic contexts. We use this dataset, which we make publicly available, to probe the behavior of current state-of-the-art neural systems, showing that these systems make certain systematic errors that are clearly visible through the lens of factuality prediction.
Regression Rate Model Predictions of an Axial-Injection End-Burning Hybrid Motor

This paper investigated the predictions of the axial-injection end-burning hybrid rocket motor regression rate model developed by Hitt and Frederick. Because axial-injection end-burning hybrid rock...
Clinical performance of intentionally tilted implants versus axially positioned implants: A systematic review

Objectives The aim of this review was to determine the clinical performance of dental implants that are intentionally tilted when compared with implants that are placed following the long axis of the residual alveolar ridge. Materials and methods A systematic review of the scientific literature using a predefined research question (PICO) and search strategy was undertaken. This search included five electronic databases. Two independent reviewers examined electronic databases and performed a manual review following search strategy to accomplish the item generation and reduction. Included articles were evaluated to determine the level of evidence. Data were extracted only from level I and level II studies, based on the Oxford Centre for Evidence-based Medicine-Levels of Evidence (March 2009). If included studies were homogeneous in nature, data were to be accumulated. However, if included studies were heterogeneous in nature, only descriptive data would be reviewed and analyzed. Results A total of 811 articles were identified through the PICO question and search strategy. Detailed review of the abstracts and articles resulted in further item reduction, and 46 articles were included for full-text review. A total of 42 articles were then selected for inclusion in the systematic review. The identified articles included two level I and 20 level II studies. In addition, 15 level IV, one gray literature, and four previous systematic reviews with meta-analyses were also used in the study. The extracted data from the included studies demonstrated heterogeneity that prevented quantitative assessment, and only one level II study directly compared tilted and axially placed implants. Assessment of the descriptive data demonstrated no differences in implant survival, marginal bone loss, prosthesis survival, or patient-reported outcome measures (PROMs) whether implants are placed axially or with intentional inclination of the coronal aspect of the implant toward the distal aspect of edentulous jaws. Conclusions Based upon the systematic review of the literature, an analysis of the descriptive data suggested no differences in clinical performance between implants that are placed in an axial position relative to the residual alveolar ridge when compared with implants that are intentionally tilted toward the distal aspect of edentulous jaws.
Analytical Assessment of Drag-Modulation Trajectory Control for Planetary Entry

Discrete-event drag-modulation trajectory control is assessed for planetary entry using the closed-form Allen-Eggers solution to the equations of motion. A control authority metric for drag-modulation trajectory control systems is derived. Closed-form analytical relationships are developed to assess range divert capability and to identify jettison condition constraints for limiting peak acceleration and peak heat rate. Closed-form relationships are also developed for drag-modulation systems with an arbitrary number of stages.
Win or Lose: Residential Sorting After a School Choice Lottery

We examine residential relocation and opting out of the public school system in response to school choice lottery outcomes. We show that rising kindergartners and sixth graders who lose a school ch...
Political Popularity Analysis in Social Media

Popularity is a critical success factor for a politician and her/his party to win in elections and implement their plans. Finding the reasons behind the popularity can provide a stable political movement. This research attempts to measure popularity in Twitter using a mixed method. In recent years, Twitter data has provided an excellent opportunity for exploring public opinions by analyzing a large number of tweets. This study has collected and examined 4.5 million tweets related to a US politician, Senator Bernie Sanders. This study investigated eight economic reasons behind the senator’s popularity in Twitter. This research has benefits for politicians, informatics experts, and policymakers to explore public opinion. The collected data will also be available for further investigation.
Some results relevant to embeddability of rings (especially group algebras) in division rings

Abstract P. M. Cohn showed in 1971 that given a ring R , to describe, up to isomorphism, a division ring D generated by a homomorphic image of R is equivalent to specifying the set of square matrices over R which map to singular matrices over D , and he determined precisely the conditions that such a set of matrices must satisfy. The present author later developed another version of this data, in terms of closure operators on free R -modules. In this note, we examine the latter concept further, and show how an R -module M satisfying certain conditions can be made to induce such data. In an appendix we make some observations on Cohn's original construction, and note how the data it uses can similarly be induced by an appropriate sort of R -module. Our motivation is the longstanding question of whether, for G a right-orderable group and k a field, the group algebra kG must be embeddable in a division ring. Our hope is that the right kG -module M = k ( ( G ) ) might induce a closure operator of the required sort. We re-prove a partial result in this direction due to N. I. Dubrovin, note a plausible generalization thereof which would give the desired embedding, and also sketch some thoughts on other ways of approaching the problem.
Gender gaps in equity crowdfunding: Evidence from a randomized field experiment

Although prior research in traditional equity financing shows that male founders are preferred, emerging evidence in low-stakes crowdfunding (e.g., rewards-based crowdfunding) indicates that female...
Libertarian paternalism: taking Econs seriously

There is an extensive critical literature analyzing the libertarian paternalism (LP) of Richard Thaler and Cass Sunstein. This paper is critical as well, but does so from a different perspective than most of the existing research. Thaler and Sunstein characterize LP by at least two key features: (1) a sharp distinction between Econs (those whose behavior will be unchanged by LP policies) and Humans (who will, at least potentially, change their behavior as a result of LP policies), and (2) defining Econs explicitly as homo economicus: “the textbook picture of human beings offered by economists” (Thaler and Sunstein in Nudge: improving decisions about health, wealth and happiness. Penguin, London, p. 7, 2009). This paper will take their definition of Econs seriously and examine the implications for LP-based policies. The bottom line is that if we take Econs seriously, LP nudges end up being not only extremely weak policy tools, but they also fail to accommodate some of the most important insights of behavioral economics.
The role of information in retail gasoline price dispersion

Abstract Collecting information on prices is a costly endeavor. The cost depends on the relative ease with which those prices can be collected, and in many retail gasoline markets, there is a substantial divide in the ease of collecting information with regular grade gasoline on one side of the divide and midgrade and premium grade gasoline on the other. Regular grade prices are prominently displayed on large signboards in front of gasoline stations while the prices of higher octane grades, except where required by law, are rarely displayed. In this article, the effects of differential-by-grade price information on search and gasoline price dispersion are examined. A rank reversal test is used to test whether the observed grade-specific price dispersion is consistent with search or non-search related causes and, finding the former, a series of tests are presented to test for the effect of price information and other leading hypotheses. A significantly concave curvature in the price dispersion coefficients across the three grades supports a price information hypothesis. Detailed socioeconomic data on consumers, spatially matched to the stations they are most likely to patronize, shows that income is a secondary factor. Implications for policy are discussed.
Consumer Scores and Price Discrimination

We study the implications of aggregating consumers’ purchase histories into scores that proxy for unobserved willingness to pay. A long-lived consumer interacts with a sequence of firms. Each firm relies on the consumer’s current score–a linear aggregate of noisy purchase signals—to learn about her preferences and to set prices. If the consumer is strategic, she reduces her demand to manipulate her score, which reduces the average equilibrium price. Firms in turn prefer scores that overweigh past signals relative to applying Bayes’ rule with disaggregated data, as this mitigates the ratchet effect and maximizes the firms’ ability to price discriminate. Consumers with high average willingness to pay benefit from data collection, because the gains from low average prices dominate the losses from price discrimination. Finally, hidden scores—those only observed by the firms—reduce demand sensitivity, increase average prices, and reduce consumer surplus, sometimes below the naive-consumer level.
Selective targeting of unipolar brush cell subtypes by cerebellar mossy fibers.

While out jogging, you have no trouble keeping your eyes fixed on objects in the distance even though your head and eyes are moving with every step. Humans owe this stability of the visual world partly to a region of the brain called the vestibular cerebellum. From its position underneath the rest of the brain, the vestibular cerebellum detects head motion and then triggers compensatory movements to stabilize the head, body and eyes. The vestibular cerebellum receives sensory input from the body via direct and indirect routes. The direct input comes from five structures within the inner ear, each of which detects movement of the head in one particular direction. The indirect input travels to the cerebellum via the brainstem, which connects the brain with the spinal cord. The indirect input contains information on head movements in multiple directions combined with input from other senses such as vision. By studying the mouse brain, Balmer and Trussell have now mapped the direct and indirect circuits that carry sensory information to the vestibular cerebellum. Both types of input activate cells within the vestibular cerebellum called unipolar brush cells (UBCs). There are two types of UBCs: ON and OFF. Direct sensory input from the inner ear activates only ON UBCs. These cells respond to the arrival of sensory input by increasing their activity. Indirect input from the brainstem activates both ON UBCs and OFF UBCs. The latter respond to the input by decreasing their activity. The vestibular cerebellum thus processes direct and indirect inputs via segregated pathways containing different types of UBCs. The next step in understanding how the cerebellum maintains a stable visual world is to identify the circuitry beyond the UBCs. Understanding these circuits will ultimately provide insights into balance disorders, such as vertigo.
Defining Kinetic Properties of HIV-Specific CD8+ T-Cell Responses in Acute Infection

Multiple lines of evidence indicate that CD8 + T cells are important in the control of HIV-1 (HIV) replication. However, CD8 + T cells induced by natural infection cannot eliminate the virus or reduce viral loads to acceptably low levels in most infected individuals. Understanding the basic quantitative features of CD8 + T-cell responses induced during HIV infection may therefore inform us about the limits that HIV vaccines, which aim to induce protective CD8 + T-cell responses, must exceed. Using previously published experimental data from a cohort of HIV-infected individuals with sampling times from acute to chronic infection we defined the quantitative properties of CD8 + T-cell responses to the whole HIV proteome. In contrast with a commonly held view, we found that the relative number of HIV-specific CD8 + T-cell responses (response breadth) changed little over the course of infection (first 400 days post-infection), with moderate but statistically significant changes occurring only during the first 35 symptomatic days. This challenges the idea that a change in the T-cell response breadth over time is responsible for the slow speed of viral escape from CD8 + T cells in the chronic infection. The breadth of HIV-specific CD8 + T-cell responses was not correlated with the average viral load for our small cohort of patients. Metrics of relative immunodominance of HIV-specific CD8 + T-cell responses such as Shannon entropy or the Evenness index were also not significantly correlated with the average viral load. Our mathematical-model-driven analysis suggested extremely slow expansion kinetics for the majority of HIV-specific CD8 + T-cell responses and the presence of intra- and interclonal competition between multiple CD8 + T-cell responses; such competition may limit the magnitude of CD8 + T-cell responses, specific to different epitopes, and the overall number of T-cell responses induced by vaccination. Further understanding of mechanisms underlying interactions between the virus and virus-specific CD8 + T-cell response will be instrumental in determining which T-cell-based vaccines will induce T-cell responses providing durable protection against HIV infection.
Kuznets revisited: What do we know about the relationship between structural transformation and inequality?

This paper revisits the Kuznets postulate that structural transformation will be associated with increasing inequality using comparable time series data for 32 developing and recently developed eco...
Neural Processing of Communication Signals: The Extent of Sender–Receiver Matching Varies across Species of Apteronotus

Abstract As communication signal properties change, through genetic drift or selective pressure, the sensory systems that receive these signals must also adapt to maintain sensitivity and adaptability in an array of contexts. Shedding light on this process helps us to understand how sensory codes are tailored to specific tasks. In a species of weakly electric fish, Apteronotus albifrons, we examined the unique neurophysiological properties that support the encoding of electrosensory communication signals that the animal encounters in social exchanges. We compare our findings to the known coding properties of the closely related species Apteronotus leptorhynchus to establish how these animals differ in their ability to encode their distinctive communication signals. While there are many similarities between these two species, we found notable differences leading to relatively poor coding of the details of chirp structure occurring on high-frequency background beats. As a result, small differences in chirp properties are poorly resolved by the nervous system. We performed behavioral tests to relate A. albifrons chirp coding strategies to its use of chirps during social encounters. Our results suggest that A. albifrons does not exchange frequent chirps in a nonbreeding condition, particularly when the beat frequency is high. These findings parallel the mediocre chirp coding accuracy in that they both point to a reduced reliance on frequent and rich exchange of information through chirps during these social interactions. Therefore, our study suggests that neural coding strategies in the CNS vary across species in a way that parallels the behavioral use of the sensory signals.
Exergy Analysis of Data Center Thermal Management Systems

Data center thermal management systems exist to maintain the computer equipment within acceptable operating temperatures. As power densities have increased in data centers, however, the energy used by the cooling infrastructure has become a matter of growing concern. Most existing data center thermal management metrics provide information about either the energy efficiency or the thermal state of the data center. There is a gap around a metric that fuses information about each of these goals into a single measure. This chapter addresses this limitation through an exergy analysis of the data center thermal management system. The approach recognizes that the mixing of hot and cold streams in the data center airspace, which is often a primary driver of thermal inefficiency in the data center, is an irreversible process and must therefore lead to the destruction of exergy. Experimental validation in a test data center confirms that such an exergy-based characterization in the cold aisle reflects the same recirculation trends as suggested by traditional temperature-based metrics. Further, by extending the exergy-based model to include irreversibilities from other components of the thermal architecture, it becomes possible to quantify the amount of available energy supplied to the cooling system which is being utilized for thermal management purposes. The energy efficiency of the entire data center cooling system can then be collapsed into the single metric of net exergy consumption. When evaluated against a ground state of the external ambience, this metric enables an estimate of how much of the energy emitted into the environment could potentially be harnessed in the form of useful work. The insights availed from the above analysis include a wide range of considerations, such as the viability of workload placement within the data center; the appropriateness of airside economization as well as containment; the potential benefits of reusing waste heat from the data center; as well as the potential to install additional compute capacity without needing to increase the data center cooling capacity. In addition, the analysis provides insight about how local thermal management inefficiencies in the data center can be mitigated. The chapter concludes by suggesting that the proposed exergy-based approach can provide a foundation upon which the data center cooling system can be simultaneously evaluated for thermal manageability and energy efficiency.
Minimum Wages, Morality, and Efficiency: A Choice Experiment

We use a choice experiment to examine public support for minimum wages. We first elicit respondents’ moral assessment of two labor market systems: one with a minimum wage and one without. Then, we present four pairs of hypothetical employment outcomes and ask respondents to "vote." Our estimates suggest that the average respondent requires a 4.65 percentage point reduction in unemployment before they would support a system without a minimum wage. We also find that equity matters; respondents are 11.1 percentage points less likely to support a minimum wage if it disproportionately affects minorities and females.
Low-dimensional representation of genomic sequences

Numerous data analysis and data mining techniques require that data be embedded in a Euclidean space. When faced with symbolic datasets, particularly biological sequence data produced by high-throughput sequencing assays, conventional embedding approaches like binary and k-mer count vectors may be too high dimensional or coarse-grained to learn from the data effectively. Other representation techniques such as Multidimensional Scaling (MDS) and Node2Vec may be inadequate for large datasets as they require recomputing the full embedding from scratch when faced with new, unclassified data. To overcome these issues we amend the graph-theoretic notion of "metric dimension" to that of "multilateration." Much like trilateration can be used to represent points in the Euclidean plane by their distances to three non-colinear points, multilateration allows us to represent any node in a graph by its distances to a subset of nodes. Unfortunately, the problem of determining a minimal subset and hence the lowest dimensional embedding is NP-complete for general graphs. However, by specializing to Hamming graphs, which are particularly well suited to representing biological sequences, we can readily generate low-dimensional embeddings to map sequences of arbitrary length to a real space. As proof-of-concept, we use MDS, Node2Vec, and multilateration-based embeddings to classify DNA 20-mers centered at intron-exon boundaries. Although these different techniques perform comparably, MDS and Node2Vec potentially suffer from scalability issues with increasing sequence length whereas multilateration provides an efficient means of mapping long genomic sequences.
Brittle‐ductile transition in uniaxial compression of polymer glasses

We carried out a large set of tests to establish a correlation between the molecular (network) structure (influenced by molecular weight, molecular weight distribution, and melt predeformation) and mechanical responses of several glassy polymers to uniaxial compression at different temperatures and different compression speeds. The experimental results show that to have ductile responses there must be an adequate chain network, afforded by the interchain uncrossability among sufficiently long chains. Specifically, polystyrene (PS) and poly(methyl methacrylate) of sufficiently low molar mass do not have chain network and are found to be very brittle. Binary PS mixtures are brittle at room temperature when the volume fraction of the high‐molecular‐weight component is sufficiently low (e.g., at and below 27.5%). Moreover, sufficiently melt‐stretched PS mixtures show brittle fracture when compressed along the same direction, along which melt stretching was made. All the experimental findings confirm that a robust chain network is also a prerequisite for yielding and ductile cold compression of polymer glasses, as is for extension. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 758–770
Gross profitability and mutual fund performance

Abstract We find that mutual funds holding a larger concentration of high gross profitability stocks generate better future performance. The outperformance of these funds is not driven by a profitability-related risk premium and is not a byproduct of fund managers’ exploitation of other well-known investment strategies. We show that fund managers who trade on the gross profitability anomaly possess greater skill and create value by attracting future fund inflows and by growing fund assets under management. We contribute to both the mutual fund and market anomaly literatures by providing strong evidence that a sizable subset of mutual fund managers profit from an important market anomaly.
Azathioprine suppression of natural killer activity and antibody-dependent cellular cytotoxicity in renal transplant recipients

The relative effects of azathioprine (AZA) and prednisone (PRED) on natural killer (NK) activity and the antibody-dependent cellular cytotoxicity (ADCC) of K (killer) cells and the number of FcR and other lymphoid cells were examined in renal transplant recipients. In addition to both long-term (>6 months) and short-term (<6 months) transplant recipients receiving conventional AZA-PRED therapy, an important group of long-term recipients receiving PRED but not AZA was studied for the first time. Both NK activity and ADCC are profoundly reduced in the long-term AZA-PRED group but are normal in the long-term PRED-alone (no-AZA) group. The short-term AZA-PRED group exhibits NK and ADCC levels significantly lower than normal but not as low as those of the long-term AZA-PRED group. Patient groups with low NK and ADCC also have low circulating Fc receptor-bearing (FcR) cells. A single patient in the long-term AZA-PRED group was removed from AZA therapy, and approximately 3 months was required for the patient's suppressed NK and ADCC to return to normal. These findings indicate that AZA rather than PRED is the major drug important in suppressing ADCC and NK activity in renal transplant recipients. Several months are required for combination AZA-PRED therapy to reduce these cytotoxic activities. Similarly, several months are required for suppressed ADCC and NK activity to return to normal upon discontinuation of AZA.
Matrix scaling and explicit doubly stochastic limits

Abstract The process of alternately row scaling and column scaling a positive n × n matrix A converges to a doubly stochastic positive n × n matrix S ( A ) , often called the Sinkhorn limit of A. The main result in this paper is the computation of exact formulae for the Sinkhorn limits of certain symmetric positive 3 × 3 matrices.
Meta networks

Neural networks have been successfully applied in applications with a large amount of labeled data. However, the task of rapid generalization on new concepts with small training data while preserving performances on previously learned ones still presents a significant challenge to neural network models. In this work, we introduce a novel meta learning method, Meta Networks (MetaNet), that learns a meta-level knowledge across tasks and shifts its inductive biases via fast parameterization for rapid generalization. When evaluated on Omniglot and Mini-ImageNet benchmarks, our MetaNet models achieve a near human-level performance and outperform the baseline approaches by up to 6% accuracy. We demonstrate several appealing properties of MetaNet relating to generalization and continual learning.
Asymmetric reactions of axially chiral amides: use of removable ortho-substituents in radical cyclizations of o-iodoacrylanilides and N-allyl-N-o-iodoacrylamides

Radical cyclizations of enantiomerically enriched o-iodoacrylanilides and N-allyl-o-iodoanilides bearing a removable ortho-substituent such as trimethylsilyl or bromine provide oxindoles and indoles in good yields and with good to excellent levels of chirality transfer from the N–Ar axis to the new stereocenter. Transition state models for the chirality transfer are suggested. Chemoselectivity of the radical cyclization in favor of the iodine in the case of 2-iodo-6-bromo-N-allylacrylamides has been exploited for the synthesis of chiral pyrroloquinolinones by a one-pot sequence of 5-exo and 6-endo cyclizations.
NEW APPLICATIONS OF PALLADIUM IN ORGANIC SYNTHESES

The palladium catalyzed vinylic substitution reaction with organic halides is a new and useful method for producing carbon-carbon bonds. The reaction is useful with aryl, heterocyclic, benzylic, and vinylic bromides and iodides. The most useful reactions are with bromides in which cases a triarylphosphine is required with the palladium catalyst. The best phosphine to employ for a specific synthesis can now be predicted based upon knowledge of how the phosphines influence vinylic substitution rates and side reactions forming phosphonium salts and palladium metal. Essentially all common functional groups can be tolerated by the reaction under the same conditions with the exception of α,β-unsaturated ketones and aldehydes. These react normally in the form of their acetals or ketals, however. Reactions proceed well with conjugated or isolated double bonds with mono-, di- and often tri-substituted olefins, generally in a stereospecific manner. A syn addition of the organopalladium compound to the olefin followed by a syn elimination of the palladium hydride is observed. The direction of addition of the organopalladium complex to the olefin depends upon the substituents present. Both steric and electronic influences have been observed. The direction of addition is dominated by steric effects; the organic group always adds, at least mainly, to the least substituted carbon of the double bond. Electron withdrawing substituents on the double bond generally cause exclusive addition of the organic group to the olefinic carbon not having the substituent. With electron donating groups, some addition to the carbon carrying the substituent is usually observed.
STUDIES DIRECTED TOWARD THE TOTAL SYNTHESIS OF KABIRAMIDE C : ASYMMETRIC SYNTHESIS OF THE C1-C19 FRAGMENT

Abstract An efficient synthesis of the C1 C6 aliphatic fragment 3 and its coupling to the C7 C19 fragment 4 of kabiramide C is described. Key transformations include a TiCl4 promoted condensation between aldehyde 5 and crotylsilane (R)-6 and a Barton-McCombie deoxygenation of the homoallylic alcohol 9 to set the stereochemical array.
Theoretical perspective of alcohol decomposition and synthesis from CO2 hydrogenation

Abstract Advances in theoretical methods, in particular density functional theory (DFT), make it possible to describe catalytic reactions at surfaces with the detail and accuracy required for computational results to compare with experiment in a meaningful way. The theoretical studies also describe chemical reaction networks and understand variations in catalytic activity from one catalyst to another. Such understanding allows the theoretical optimization for better catalysts. In the current report we discussed the theoretical studies in the past few years on decomposition and synthesis of methanol and ethanol on various catalyst surfaces. The knowledge of reactions including the intermediates and transition states along different reaction pathways together with kinetic modeling was demonstrated. The theoretical studies on alcohol synthesis help gain better understanding of the complex kinetics and the roles that each component of a catalyst plays. In general, moving from mono-functional catalysts to multi-functional catalysts by increasing the complexity offers new opportunities to tune the behavior of a catalyst. A good multi-functional catalyst is not necessary to compromise the binding strong enough to adsorb and dissociate reactants and weak enough to allow the formation of intermediates and removal of products; instead, it may take advantage of each component, which catalyzes different elementary steps depending on its unique activity. The synergy between the different components can enable the multi-functional catalyst a novel activity in catalysis. This is of great importance for rational design of better catalysts for alcohol renewal synthesis and efficient use.
Intramolecular [2 + 2]-photocycloaddition/thermal fragmentation approach toward 5-8-5 ring systems.

[reaction: see text]. An intramolecular [2 + 2]-photocycloaddition is used to provide a photoadduct, which upon fragmentation, lactone cleavage, and subsequent Cope rearrangement provides a dicyclopenta[a,d]cyclooctene ring system with substituents in place (e.g., C3 and C11) to access several 5-8-5 diterpene and sesterterpene natural products.
Synthesis and characterization of zirconogermanates.

Six new zirconogermanates have been prepared under hydrothermal conditions using amines as bases. There are four new structure types (ASU-n) with a common motif of ZrGe5. ASU-23 is a layered structure: ZrGe3O8(OH)F·[C10H26N4]·H2O, space group P21/n, a = 6.7957(8) A, b = 12.700(1) A, c = 24.293(3) A, β = 97.936(2)°, V = 2076.4(4) A3. ASU-24 is a pillared layered structure: Zr3Ge6O18(OH2,F)4F2·[C6H18N2]·[C6H17N2]2·2H2O, space group P21/n, a = 7.4249(3) A, b = 25.198(1) A, c = 11.3483(5) A, β = 90.995(1)°, V = 2122.9(2) A3. This material has the lowest framework density (FD) of any oxide material that we are aware of (FD = 8.48 metal atoms/nm3). Two other materials form three-dimensional open-frameworks, ASU-25: ZrGe3O9·[C3H12N2], space group P1121/a, a = 13.1994(4) A, b = 7.6828(2) A, c = 11.2373(3) A, γ = 91.233(3)°, V = 1139.29(5) A3. The other is ASU-26: ZrGe3O9·[C2H10N2], space group Pn, a = 13.7611(3) A, b = 7.7294(2) A, c = 11.2331(3) A, β = 104.793(1)°, V = 1155.21(4) A3. ASU-25 is related to the...
X-Ray Crystallographic and Proton Nuclear Magnetic Resonance Studies of β-Hydroxy-N-nitrosamines derived from α-Amino Acids and Ephedrine

Abstract β-Hydroxy-N-nitrosamines derived from l -leucine, l -valine, l -phenylalanine, d -phenylglycine and (1R,2S)-ephedrine have been synthesized and analyzed. These compounds all exhibit rotameric populations of (E)- and (Z)-stereoisomers that are a result of the barrier to rotation about the N-nitroso (N–NO) group. A correlation is made between the X-ray crystallographic data of the N-nitroso-ephedrine derivative 6 and the 1H NMR of the N-nitrosamines 4a–4d. From this comparison, the identities and ratios of (E)- and (Z)-rotamers were unambiguously assigned. Finally, the 1H NMR also provides some insight into the conformational changes that occur when the nitrosamine rotamers interconvert.
Chemistry at diplatinum centers

Publisher Summary This chapter describes dimeric complexes containing unsupported metal–metal bonds, followed by those bridged by simple ligands, such as halides or hydrides, then a number of compounds with bridging organic fragments. The number and variety of dimeric complexes have increased tremendously, however, with the availability of several bidentate ligands of a bite size suitable to coordinate in a bridging fashion. Most notable among these is bis(dipheny1phosphino) methane (dppm), and the remarkable versatility of this ligand has prompted the development of a number of analogs of dppm. Dppm and related ligands have been used to support dimeric complexes, containing platinum in the formal oxidation states 0, I, II, III, or IV. These ligands confer substantial stability on the diplatinum system, such that substitution, oxidative addition, and reductive elimination reactions within a dimeric framework can be investigated.
THERMOCHEMISTRY OF SULFENIC ESTERS (RSOR') : NOT JUST ANOTHER PRETTY PEROXIDE

A computational study on the thermochemistry of several simple sulfenic acids (RSOH) and esters (RSOR‘) is reported. The enthalpies of R−S, S−O, and O−R‘ homolytic cleavage are calculated at the G2...
Stability criteria for complex microbial communities

Competition and mutualism are inevitable processes in microbial ecology, and a central question is which and how many taxa will persist in the face of these interactions. Ecological theory has demonstrated that when direct, pairwise interactions among a group of species are too numerous, or too strong, then the coexistence of these species will be unstable to any slight perturbation. Here, we refine and to some extent overturn that understanding, by considering explicitly the resources that microbes consume and produce. In contrast to more complex organisms, microbial cells consume primarily abiotic resources, and mutualistic interactions are often mediated through the mechanism of crossfeeding. We show that if microbes consume, but do not produce resources, then any positive equilibrium will always be stable to small perturbations. We go on to show that in the presence of crossfeeding, stability is no longer guaranteed. However, positive equilibria remain stable whenever mutualistic interactions are either sufficiently weak, or when all pairs of taxa reciprocate each other's assistance.
Evaluation of TagSeq, a reliable low‐cost alternative for RNAseq

RNAseq is a relatively new tool for ecological genetics that offers researchers insight into changes in gene expression in response to a myriad of natural or experimental conditions. However, standard RNAseq methods (e.g., Illumina TruSeq® or NEBNext® ) can be cost prohibitive, especially when study designs require large sample sizes. Consequently, RNAseq is often underused as a method, or is applied to small sample sizes that confer poor statistical power. Low cost RNAseq methods could therefore enable far greater and more powerful applications of transcriptomics in ecological genetics and beyond. Standard mRNAseq is costly partly because one sequences portions of the full length of all transcripts. Such whole-mRNA data are redundant for estimates of relative gene expression. TagSeq is an alternative method that focuses sequencing effort on mRNAs' 3' end, reducing the necessary sequencing depth per sample, and thus cost. We present a revised TagSeq library construction procedure, and compare its performance against NEBNext® , the 'gold-standard' whole mRNAseq method. We built both TagSeq and NEBNext® libraries from the same biological samples, each spiked with control RNAs. We found that TagSeq measured the control RNA distribution more accurately than NEBNext® , for a fraction of the cost per sample (~10%). The higher accuracy of TagSeq was particularly apparent for transcripts of moderate to low abundance. Technical replicates of TagSeq libraries are highly correlated, and were correlated with NEBNext® results. Overall, we show that our modified TagSeq protocol is an efficient alternative to traditional whole mRNAseq, offering researchers comparable data at greatly reduced cost.
The preparation of benzoisothiazolo[1,2-b][1,2]isoquinolin-11-one-1,1-dioxides from dilithiated ortho-toluic acids and lithiated methyl 2-(aminosulfonyl)benzoate

Select dilithiated ortho-toluic acids were prepared in excess lithium diisopropylamide and condensed with methyl 2-(aminosulfonyl)benzoate followed by a twofold cyclization of intermediates to afford benzoisothiazolo[1,2-b][1,2]isoquinolin-11-one-1,1-dioxides, a new fused-ring heterocyclic system.
Reactions of P(MeNCH2CH2)3N with primary, secondary, and tertiary alkyl halides: Evidence for a solvent‐enhanced dehydrohalogenation

The reactions of P(MeNCH2CH2)3N, 1, with Mel, EtI, EtBr, n-PrBr, n-BuI, i-PrBr, PhCH2CHBrCH3, MeCHBr(CH2)4Me, s-BuBr, and t-BuBr were studied. The reactions of the primary alkyl halides produced the corresponding phosphonium cationic compounds, whereas the secondary and tertiary halides underwent elimination to form the corresponding olefins and the protonated form of 1. Based on 1H and 13C NMR studies, it appears that elimination is exclusively trans, favoring the Saytzeff product. It was also observed that this reaction is enhanced by the solvent CH3CN. The X-ray crystal structure of [Me(I)] I is also reported, featuring a transannular distance of 2.773 A (2) facilitated by a rather wide average equatorial MeN-P-NMe bond angle of 113.1 (2)°. © 1996 John Wiley & Sons, Inc.
Aerodynamic Characteristics of a Feathered Dinosaur Measured Using Physical Models. Effects of Form on Static Stability and Control Effectiveness

We report the effects of posture and morphology on the static aerodynamic stability and control effectiveness of physical models based on the feathered dinosaur, Microraptor gui, from the Cretaceous of China. Postures had similar lift and drag coefficients and were broadly similar when simplified metrics of gliding were considered, but they exhibited different stability characteristics depending on the position of the legs and the presence of feathers on the legs and the tail. Both stability and the function of appendages in generating maneuvering forces and torques changed as the glide angle or angle of attack were changed. These are significant because they represent an aerial environment that may have shifted during the evolution of directed aerial descent and other aerial behaviors. Certain movements were particularly effective (symmetric movements of the wings and tail in pitch, asymmetric wing movements, some tail movements). Other appendages altered their function from creating yaws at high angle of attack to rolls at low angle of attack, or reversed their function entirely. While M. gui lived after Archaeopteryx and likely represents a side experiment with feathered morphology, the general patterns of stability and control effectiveness suggested from the manipulations of forelimb, hindlimb and tail morphology here may help understand the evolution of flight control aerodynamics in vertebrates. Though these results rest on a single specimen, as further fossils with different morphologies are tested, the findings here could be applied in a phylogenetic context to reveal biomechanical constraints on extinct flyers arising from the need to maneuver.
Development of asymmetric synthesis of optically active compounds including fluoroorganic molecules

The synthesis of chiral fluorinated molecules is important in the biological and medicinal chemistry fields in view of the influence of fluorine's unique properties on biological activity. In recent years, we have studied asymmetric synthesis focussing on such optically active compounds. This review describes 1) diastereoselective trifluoromethylation of chiral N-acyloxazolidinones, 2) catalytic enantioselective aldol reactions of fluorine-substituted ketene silyl acetals, and 3) catalytic enantioselective allylation of aldehydes mediated by chiral Lewis bases. The trifluoromethylation of lithium enolates of N-acyloxazolidinones with iodotrifluoromethane is mediated by triethylborane to give the corresponding trifluoromethylated products with up to 86% diastereomeric excess. The stereoselective reaction is considered to proceed through the attack of the trifluoromethyl radical on the less hindered face of the lithium imide. Difluoroketene and bromofluoroketene trimethylsilyl ethyl acetals react with various aldehydes in the presence of chiral Lewis acids to afford the corresponding desired aldols with up to 99% enantiomeric excess (ee). It is noteworthy that the aldol reactions of the fluorine-substituted acetals at -78 degrees C and at higher temperatures (-45 or -20 degrees C) provide the (+)- and (-)-aldols, respectively, with excellent-to-good enantioselectivity. Chiral phosphoramides newly prepared from (S)-proline were found to catalyze the allylation and crotylation of aromatic aldehydes with allylic trichlorosilanes in good enantioselective yields (up to 90% ee). (S,S)-Bis(alpha-methylbenzyl)formamide developed as an efficient catalyst for the allylation and crotylation of aliphatic aldehydes mediates the enantioselective addition with the assistance of hexamethylphosphoramide (HMPA) to afford the corresponding homoallylic alcohols in up to 98% ee.
Tartaric Acid and Tartrates in the Synthesis of Bioactive Molecules

A review on the syntheses of bioactive compounds published since 1995 using tartaric acid and its derivatives as synthons is presented.
LAH aryl alkyl ether cleavage of BINOL derivatives

Abstract Herein we report the cleaving of aryl alkyl ethers on BINOL derivatives, using the common reducing agent LAH. The cleavage of the alkyl oxygen bond is observed when the BINOL derivative is treated with LAH, in refluxing dioxane, for 60 h. The resulting BINOL derivative can then be re-alkylated using a standard Williamson ether synthesis. The same procedure was tested on 6-hydroxy-2-naphthoic acid derivatives and cleavage was not observed, thus suggesting a chelating mechanism for the BINOL ether cleavage.
Regioselective synthesis of aniline-derived 1,3- and Ci-symmetric 1,4-diols from trans-1,4-cyclohexadiene dioxide.

trans-Diepoxide 1 is well-known to react with aliphatic amines and the azide ion to give exclusively the 1,3-diol products. However, we observed that by judicious choice of conditions, reaction wit...