cssi/SciSciGPT-SciSciNet huggingface dataset:
Trajectory Design Leveraging Low-Thrust, Multi-Body Equilibria and their Manifolds

A key challenge in low-thrust trajectory design is generating preliminary solutions that simultaneously specify the spacecraft position and velocity vectors, as well as the thrust history. To mitigate this difficulty, dynamical structures within a combined low-thrust circular restricted 3-body problem (CR3BP) are investigated as candidate solutions to seed initial low-thrust trajectory designs. The addition of a low-thrust force to the CR3BP modifies the locations and stability of the equilibria, offering novel geometries for mission applications. Transfers between these novel equilibria are constructed by leveraging the associated stable and unstable manifolds and insights from the low-thrust CR3BP.
Objective Donor Scoring System for Lung Transplantation.

Background There is no objective method to estimate post–lung transplant survival solely on the basis of cumulative donor risk factors. Methods The United Network Organ Sharing thoracic transplant database was queried to identify patients who underwent lung transplantation between 2005 and 2015. A Cox proportional hazard model was generated using a training set to identify donor risk factors significantly associated with posttransplant survival. Significant donor risk factors were assigned a score on the basis of their hazard ratio. Donor risk score was calculated for each patient by adding the individual donor risk factor scores. Donors in the validation set were then categorized into low-risk (score = 0), intermediate-risk (score = 1), and high-risk (score >1) categories on the basis of the cumulative risk score. The Lung Allocation Score was used as a surrogate for recipient risk. Survival for each risk group was calculated using Kaplan-Meier curves. Results The donor risk groups’ respective survival at 1 year was 85%, 81%, and 77%, and at 5 years it was 53%, 50%, and 42% (p Conclusions The proposed lung donor scoring system is a simple, easy to use method that can aid transplant surgeons in the selection of a potential lung transplant donor. Using the lung donor score in conjunction with the Lung Allocation Score can allow for matching of recipients and donors, to optimize posttransplant outcomes.
DEEP LEARNING BASED POWER CONTROL FOR QUALITY-DRIVEN WIRELESS VIDEO TRANSMISSIONS

In this paper, wireless video transmission to multiple users under total transmission power and minimum required video quality constraints is studied. In order to provide the desired performance levels to the end-users in real-time video transmissions while using the energy resources efficiently, we assume that power control is employed. Due to the presence of interference, determining the optimal power control is a non-convex problem but can be solved via monotonic optimization framework. However, monotonic optimization is an iterative algorithm and can often entail considerable computational complexity, making it not suitable for real-time applications. To address this, we propose a learning-based approach that treats the input and output of a resource allocation algorithm as an unknown nonlinear mapping and a deep neural network (DNN) is employed to learn this mapping. This learned mapping via DNN can provide the optimal power level quickly for given channel conditions.
Gastrointestinal Dysfunction in Parkinson’s Disease

During the past 25 years, there has been an explosion of information regarding the occurrence of gastrointestinal dysfunction in Parkinson’s disease. In this review, the clinical features of gastrointestinal dysfunction in Parkinson’s disease will be described and information regarding the potential role of the enteric nervous system and the gut microbiome in the genesis of Parkinson’s disease will be addressed. Recognition is growing regarding the role that gastroparesis and small intestinal dysfunction may play in Parkinson’s disease, especially with regard to erratic responses to anti-Parkinson medication. The presence of enteric nervous system involvement in Parkinson’s disease is now well established, but whether the enteric nervous system is the starting point for Parkinson’s disease pathology remains a source of debate. The potential role of the gut microbiome also is beginning to emerge. Gastrointestinal dysfunction is a prominent nonmotor feature of Parkinson’s disease and dysfunction can be found along the entire length of the gastrointestinal tract. The enteric nervous system is clearly involved in Parkinson’s disease. Whether it is the initial source of pathology is still a source of controversy. There also is growing recognition of the role that the gut microbiome may play in Parkinson’s disease, but much more research is needed to fully assess this aspect of the disorder.
Defining Learning in Educational Leadership: Reframing the Narrative:

Purpose: The purpose of this article is to reframe our field’s narrative around the science of learning. We seek to (1) describe the patterns within educational leadership and administration that a...
Nutrition and Health from Womb to Tomb

Fulfilment of the genetic potential of individuals is impaired by malnutrition and other environmental factors throughout life. The impact of nutritional factors in early childhood helps to explain why the known adult risk factors, demonstrable in populations, are poor predictors of cardiovascular disease in individuals. The combined findings of early and later risk factors strengthen the conclusion that the bulk of so-called degenerative diseases and many other functional impairments in adult life occur because of environmental factors, of which diet may be the most important. The apparent increased susceptibility to degenerative diseases of adults born small-for-date suggests that the increase in meat, fat, and calorie consumption with rising affluence is particularly hazardous for formerly poorly nourished populations. Articles confirming the nutritional origins of a wide range of diseases and disabilities at all ages increasingly predominate in the health-related scientific literature. Recognition tha...
Are We Finnished Yet? Teacher Preparation and the Rise of “Glocalization”:

The successes of the Finnish approach in teacher preparation and related school practices and policies are discussed. A narrative literature review methodology is used to determine the key policy u...
Applications of Chebyshev polynomials to low-dimensional computational geometry

We apply the polynomial method — specifically, Chebyshev polynomials — to obtain a number of new results on geometric approximation algorithms in low constant dimensions. For example, we give an algorithm for constructing $\varepsilon$-kernels (coresets for approximate width and approximate convex hull) for any $d$-dimensional $n$-point set in near-optimal time, close to $O(n+(1/\varepsilon)^{(d-1)/2})$, ignoring a small $(1/\varepsilon)^{3/2+o(1)}$ factor. We obtain an improved data structure for Euclidean approximate nearest neighbor search with close to $O(n\log n + (1/\varepsilon)^{d/4}n)$ preprocessing time and $O((1/\varepsilon)^{d/4}\log n)$ query time. We obtain improved approximation algorithms for discrete Voronoi diagrams , diameter , and bichromatic closest pair in the $L_s$-metric for any even integer constant $s\ge 2$. The techniques are general and may have further applications.
Comparison of Screening Full-Field Digital Mammography and Digital Breast Tomosynthesis Technical Recalls

Enhancing quality using the inspection program (EQUIP) augments the FDA/MQSA program ensuring image quality review and implementation of corrective processes. We compared technical recalls between digital breast tomosynthesis (DBT) and full-field digital mammography (FFDM). Prospectively recorded technical recalls of consecutive screening mammograms (10/2013 – 12/2017) were compared for imaging modality [FFDM, DBT + FFDM, DBT + synthesized mammography (SynM)], images requested, and indication(s) (motion, positioning, technical/artifact). Chi-squared tests evaluated statistical significance between proportions. Of 48,324 screening mammograms, 277 (0.57%) patients were recalled for 360 indications with 371 repeated views. DBT exams had significantly less recalls compared to FFDM (X2 = 25.239; p = 0 < 0.001). 98 (27.2%) recalls were for motion, 192 (53.3%) positioning, and 70 (19.4%) technique/artifacts. Theses indications for technical recall were compared for FFDM, DBT + FFDM, and DBT + SynM. There were significant differences in the indications for technical recall prior to and after implementing DBT + SynM (X2 = 18.719; p < 0.001). Technical recalls declined significantly with the inclusion of DBT (SynM/FFDM) compared to FFDM alone. Recalls for motion demonstrated the greatest decrease. Positioning remains a dominant factor for technical recall regardless of modality, supporting the opportunity for continued technologist education in positioning to decrease technical recalls.
Legislative bargaining and partisan delegation

We use an extension of the Baron–Ferejohn model of legislative bargaining in which there are three legislators, two of whom have partisan ties, to analyze the division of a fixed political resource...
Learning Navigation Behaviors End-to-End With AutoRL

We learn end-to-end point-to-point and path-following navigation behaviors that avoid moving obstacles. These policies receive noisy lidar observations and output robot linear and angular velocities. The policies are trained in small, static environments with AutoRL, an evolutionary automation layer around reinforcement learning (RL) that searches for a deep RL reward and neural network architecture with large-scale hyper-parameter optimization. AutoRL first finds a reward that maximizes task completion and then finds a neural network architecture that maximizes the cumulative of the found reward. Empirical evaluations, both in simulation and on-robot, show that AutoRL policies do not suffer from the catastrophic forgetfulness that plagues many other deep reinforcement learning algorithms, generalize to new environments and moving obstacles, are robust to sensor, actuator, and localization noise, and can serve as robust building blocks for larger navigation tasks. Our path-following and point-to-point policies are, respectively, 23% and 26% more successful than comparison methods across new environments.
Managerial Control and Executive Compensation

This article analyzes the trajectory and causes of the explosion of American corporate CEOs’ compensation relative to that of average workers between 1958 and 2017. The historical data are presented and analyzed in more detail for 2016 and 2017. Important biases in alternative data sets are explored. Alternative hypotheses for the dramatic changes over time are proposed but not resolved. Among other things, the paper investigates the role of tax and other government policy changes and regulation-induced innovations in the organization of executive pay determination.
Friis Free-Space Transmission Formula

The Friis transformation formula predicts the power available at the terminals of a receiving antenna due to the power applied to a transmitting antenna when the two are well separated. It is often given in logarithmic form, using decibels. It is assumed that the transmission occurs in free space, that the separation is sufficient to satisfy the far-field criterion for antennas, and that the antennas are matched in polarization (i.e., the polarization of the receiving antenna is optimum for the polarization of the transmitted wave). The formula, first published by Harald T. Eriis in 1946, is easily derivable from basic physical principles. Keywords: propagation; transmission; antenna; free space; far field; antenna polarization; Fraunhofer region
The fleeting, unhappy affair of Amazon HQ2 and New York City

This essay analyses New York's 2018 proposal to Amazon to locate their second headquarters (HQ2) in New York City. In addition to the massive resources and infrastructure offered by the city to Ama...
Individualized Multilayer Tensor Learning With an Application in Imaging Analysis

This work is motivated by multimodality breast cancer imaging data, which is quite challenging in that the signals of discrete tumor-associated microvesicles are randomly distributed with heterogen...
Acquired Factor X Deficiency in Patients With Primary Light Chain Amyloidosis

Acquired factor X (FX) deficiency is a rare but serious complication of primary amyloidosis, presumably caused by the binding of amyloid proteins to the clotting factors. The prolonged prothrombin time, partial thromboplastin time, and low FX level, which are correctable by mixing study, are the disease hallmarks. An immediate goal of care is to stop bleeding. Clotting factor replacement requires close monitoring of coagulogram and FX levels due to varying FX clearance among patients. High-purity FX is currently approved for hereditary FX deficiency and has been successfully used in some acquired FX deficiency cases. Ongoing bleeding risk complicates the treatment decision. Novel therapies yielding rapid and deep response reduce amyloid protein production and improve long-term outcome.
‘You’re in the basement of this grand house…:’ habitus reformation and elite cultural capital acquisition among women of color

This study explores habitus (re)formation and elite cultural capital acquisition among 37 lower to middle-income women of color who accessed a high-income, predominantly white suburban public high ...
DAG-GNN: DAG Structure Learning with Graph Neural Networks

Learning a faithful directed acyclic graph (DAG) from samples of a joint distribution is a challenging combinatorial problem, owing to the intractable search space superexponential in the number of graph nodes. A recent breakthrough formulates the problem as a continuous optimization with a structural constraint that ensures acyclicity (Zheng et al., 2018). The authors apply the approach to the linear structural equation model (SEM) and the least-squares loss function that are statistically well justified but nevertheless limited. Motivated by the widespread success of deep learning that is capable of capturing complex nonlinear mappings, in this work we propose a deep generative model and apply a variant of the structural constraint to learn the DAG. At the heart of the generative model is a variational autoencoder parameterized by a novel graph neural network architecture, which we coin DAG-GNN. In addition to the richer capacity, an advantage of the proposed model is that it naturally handles discrete variables as well as vector-valued ones. We demonstrate that on synthetic data sets, the proposed method learns more accurate graphs for nonlinearly generated samples; and on benchmark data sets with discrete variables, the learned graphs are reasonably close to the global optima. The code is available at \url{this https URL}.
The medium-run and scale-up effects of performance-based financing: An extension of Rwanda’s 2006 trial using secondary data

Abstract Performance-based financing (PBF) programs have been introduced in numerous developing countries to increase the provision and quality of health services through financial incentives. Despite growing evidence about short-term impacts of PBF, less is known about medium-run impacts and scale-up effects, and about how PBF compares to other financing approaches. In this paper, we extend the initial evaluation of Rwanda’s PBF program to identify medium-run and scale-up effects of incentives and unconditional financing relative to a new “business as usual” counterfactual. We use data from the Demographic and Health Surveys from Rwanda and several Sub-Saharan African countries from 2001 to 2010, using two control group strategies: all available control regions, and a subset of regions that are similar to Rwanda based on pre-intervention trends in covariates and outcomes. We then use difference-in-differences regressions to measure the Rwandan program’s impacts on four indicators: institutional deliveries, antenatal tetanus prophylaxis, completion of any antenatal visits, and completion of four antenatal visits. The results are similar using the various control groups and in additional robustness checks. In the short-run and relative to no intervention, both performance-based and unconditional financing raised institutional delivery rates and completion of four antenatal visits. In the medium-run, relative to no intervention and in addition to the initial short-run impacts, performance-based incentives resulted in further improvements for institutional deliveries. Program scale-up was effective, with few differences between intervention arms after all areas received performance-based incentives. There were few effects on antenatal tetanus prophylaxis or on completion of any antenatal visits. Together, the results suggest that PBF can have persistent effects for some indicators, but unconditional financing can also be effective. Moreover, the analysis demonstrates how observational research methods and secondary data can generate new insights on completed trials.
THE DETERMINANTS OF ECONOMIC FREEDOM: A SURVEY

A large literature has found positive associations between economic freedom and income, growth, and a variety of other desirable outcomes. This paper surveys the literature that seeks to explain the causes of economic freedom. Some of the most consistent findings in this literature are that current levels of economic freedom are strongly correlated with past levels; freer countries have more difficulty continuing to improve their economic freedom; democracy and political freedom are positively associated with economic freedom; and inequality is negatively related. (JEL E02, E14, O17, O43, P1)
Canine impaction – A review of the prevalence, etiology, diagnosis and treatment

Abstract The signs and symptoms of canine impaction can vary, with patients only noticing symptoms when they are suffering from unsightly esthetics, faulty occlusion, or poor cranio-facial development. While various surgical interventions have been proposed to expose and help erupt impacted canines, these treatment modalities have a high degree of difficulty compared to other types of dental cosmetic surgeries. This paper focuses on multi-disciplinary strategies for treating and managing canine impaction, reviews patient and clinical selection criteria, and discusses the evidence underlying existing interventions to reduce complications and improve patient-centered outcomes following treatment.
Presidential congruence and happiness: the role of extreme political views

Previous literature has demonstrated that individuals in the US report greater happiness when the president is of the same party that the individual identifies with. It has likewise been demonstrat...
Reactions and Reactivity of Acyloxycarbenes

Phenylacetoxycarbene, phenyl(pivaloyloxy)carbene, and phenyl(benzoyloxy)carbene, photolytically generated from diazirine precursors in pentane at 25 °C, efficiently rearranged by 1,2-acyl migrations to give high yields of the appropriate 1,2-diketones. The kinetics of these rearrangements were determined by laser flash photolysis. Substituent effects on the acyl migrations and ab initio electronic structure calculations on ground state carbenes and transition states were employed to analyze the rearrangement mechanism. Additions of phenylacetoxycarbene to alkenes proceeded in good yields, in lieu of the 1,2-acyl shift; absolute rate constants were obtained for these reactions of the ambiphilic carbene. (Phenoxymethyl)acetoxycarbene gave only a 1,2-H shift; the potentially competitive 1,2-acetyl migration was suppressed.
Potassium yttrium hexaniobium octadecachloride, KYNb6Cl18

The structure of potassium yttrium hexaniobium octadeca­chloride is built of anionic [Nb6Cl12iCl6a]4− cluster units (where `i' and `a' denote inner and outer ligands, respectively), linked together by K+ and Y3+ cations. The K+ cations occupy half of the tetrahedral vacancies in the face-centered cubic lattice of cluster units, and are coordinated by 12 chloride ligands. The Y atom is located in an octahedral site and is bonded to six outer chloride ligands.
A Reduced Polyoxomolybdenum Borophosphate Anion Related to the Wells-Dawson Clusters

The new compound (C3N2H5)8[MoV5MoVI7O22(BO4)2(PO4)5(HPO4)3]·nH2O is the first molybdenum borophosphate. It contains clusters of twelve molybdenum, eight phosphorus and two boron atoms, [Mo12O22(BO4)2(PO4)5(HPO4)3]8- similar to the Wells−Dawson clusters. Five molybdenum atoms are MoV while the others are MoVI, and the five electrons are delocalized. According to the temperature dependence of the magnetic susceptibility four of these electrons are paired.
Striatal cholinergic receptor activation causes a rapid, selective and state-dependent rise in cortico-striatal β activity.

Cortico-basal ganglia-thalamic (CBT) β oscillations (15-30 Hz) are elevated in Parkinson's disease and correlated with movement disability. To date, no experimental paradigm outside of loss of dopamine has been able to specifically elevate β oscillations in the CBT loop. Here, we show that activation of striatal cholinergic receptors selectively increased β oscillations in mouse striatum and motor cortex. In individuals showing simultaneous β increases in both striatum and M1, β partial directed coherence (PDC) increased from striatum to M1 (but not in the reverse direction). In individuals that did not show simultaneous β increases, β PDC increased from M1 to striatum (but not in the reverse direction), and M1 was characterized by persistent β-high frequency oscillation phase-amplitude coupling. Finally, the direction of β PDC distinguished between β sub-bands. This suggests that (1) striatal cholinergic tone exerts state-dependent and frequency-selective control over CBT β power and coordination; (2) ongoing rhythmic dynamics can determine whether elevated β oscillations are expressed in striatum and M1; and (3) altered striatal cholinergic tone differentially modulates distinct β sub-bands.
Effect of catalyst on the diastereoselectivity of methyl phenyldiazoacetate cyclopropanations

Abstract In contrast to previously published studies, the diastereoselectivity of phenyldiazoacetate cyclopropanations is not greatly altered by the type of rhodium car☐ylate catalyst that is used
Dienophilicity of imidazole in inverse electron demand Diels–Alder reactions: cycloadditions with 1,2,4,5-tetrazines and the structure of zarzissine

Abstract The inverse electron demand cycloadditions of 2-substituted imidazoles with dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate produced imidazo[4,5-d]pyridazines in good yields. This chemistry was applied to the synthesis of 2-amino-1H-imidazo[4,5-d]pyridazine (1), the structure reported for zarzissine, a cytotoxic marine alkaloid. Differences in the 1H- and 13C NMR spectra of 1 with those reported for zarzissine necessitated a structural revision, and zarzissine was then considered to be the corresponding 2-amino-1H-imidazo[4,5-b]pyrazine (2), which was subsequently synthesized from the parent heterocycle.
Homogeneous Catalysis and Catalyst Recovery Using Supercritical Carbon Dioxide and Ionic Liquids

The combination of scCO2 with a non-volatile liquid such as ionic liquids, water, or poly (ethylene glycol) creates a biphasic mixture suitable for homogeneous catalysis with facile catalyst/product separation and catalyst recycling. Continuous-flow processes are also possible. Dissolution of the CO2 into the nonvolatile liquid during the reaction can have desirable or undesirable effects on the properties of the liquid phase and the reaction performance. Examples of the use of these biphasic systems are described, with an emphasis on systems involving ionic liquids.
An ionic liquid-tagged second generation Hoveyda-Grubbs ruthenium carbene complex as highly reactive and recyclable catalyst for ring-closing metathesis of di-, tri- and tetrasubstituted dienes

A second generation Hoveyda–Grubbs ruthenium carbene complex bearing an ionic liquid tag was prepared and shown to be a highly reactive catalyst for the ring-closing metathesis of di-, tri- and tetrasubstituted diene and enyne substrates in minimally ionic solvent systems ([Bmim]PF6/CH2Cl2, 1:9–1:1 v/v). Both the catalyst and the ionic liquid can be conveniently recycled and repeatedly reused (up to 17 cycles) with only a very slight loss of activity. The ionic liquid tag is crucial to the high level of recyclability of the catalyst since the original second generation Grubbs and Hoveyda–Grubbs catalysts rapidly lose their activity when recycled in the ionic liquid layer.
Ambiphilic reactivity of 1,1-dimethoxyacetone

Abstract Trialkylsilyloxyallyl cations 2 with a π-donating methoxy substituent at the allylic termini are generated from nonhalogenated substrates via treatment of 5b-e with Lewis acids. 2 undergoes stereo- and regioselective cycloaddition with furans yielding 2-methoxy-8-oxabicyclo[3.2.1] oct-6-en-3-ones. Cycloadduct 7 is converted to 2-methoxytropone 14 and thus represents an efficient entry into tropolonoid systems.
Synthesis of 1,2-Diamines via Hydroamination Reactions

A brief overview of the synthesis of 1,2-diamines using hydroamination reaction of alkenes is presented herein. In addition, the most recent breakthrough in this field showcasing the intermolecular hydroamination of N-allyl imines is discussed.
Retrospective whole-genome sequencing analysis distinguished PFGE and drug-resistance-matched retail meat and clinical Salmonella isolates.

Non-typhoidal Salmonella is a leading cause of outbreak and sporadic-associated foodborne illnesses in the United States. These infections have been associated with a range of foods, including retail meats. Traditionally, pulsed-field gel electrophoresis (PFGE) and antibiotic susceptibility testing (AST) have been used to facilitate public health investigations of Salmonella infections. However, whole-genome sequencing (WGS) has emerged as an alternative tool that can be routinely implemented. To assess its potential in enhancing integrated surveillance in Pennsylvania, USA, WGS was used to directly compare the genetic characteristics of 7 retail meat and 43 clinical historic Salmonella isolates, subdivided into 3 subsets based on PFGE and AST results, to retrospectively resolve their genetic relatedness and identify antimicrobial resistance (AMR) determinants. Single nucleotide polymorphism (SNP) analyses revealed that the retail meat isolates within S. Heidelberg, S. Typhimurium var. O5- subset 1 and S. Typhimurium var. O5- subset 2 were separated from each primary PFGE pattern-matched clinical isolate by 6–12, 41–96 and 21–81 SNPs, respectively. Fifteen resistance genes were identified across all isolates, including fosA7, a gene only recently found in a limited number of Salmonella and a ≥95 % phenotype to genotype correlation was observed for all tested antimicrobials. Moreover, AMR was primarily plasmid-mediated in S. Heidelberg and S. Typhimurium var. O5- subset 2, whereas AMR was chromosomally carried in S. Typhimurium var. O5- subset 1. Similar plasmids were identified in both the retail meat and clinical isolates. Collectively, these data highlight the utility of WGS in retrospective analyses and enhancing integrated surveillance for Salmonella from multiple sources.
Making the Case for Conformal Gravity

We review some recent developments in the conformal gravity theory that has been advanced as a candidate alternative to standard Einstein gravity. As a quantum theory the conformal theory is both renormalizable and unitary, with unitarity being obtained because the theory is a PT symmetric rather than a Hermitian theory. We show that in the theory there can be no a priori classical curvature, with all curvature having to result from quantization. In the conformal theory gravity requires no independent quantization of its own, with it being quantized solely by virtue of its being coupled to a quantized matter source. Moreover, because it is this very coupling that fixes the strength of the gravitational field commutators, the gravity sector zero-point energy density and pressure fluctuations are then able to identically cancel the zero-point fluctuations associated with the matter sector. In addition, we show that when the conformal symmetry is spontaneously broken, the zero-point structure automatically readjusts so as to identically cancel the cosmological constant term that dynamical mass generation induces. We show that the macroscopic classical theory that results from the quantum conformal theory incorporates global physics effects that provide for a detailed accounting of a comprehensive set of 138 galactic rotation curves with no adjustable parameters other than the galactic mass to light ratios, and with the need for no dark matter whatsoever. With these global effects eliminating the need for dark matter, we see that invoking dark matter in galaxies could potentially be nothing more than an attempt to describe global physics effects in purely local galactic terms. Finally, we review some recent work by ’t Hooft in which a connection between conformal gravity and Einstein gravity has been found.
Identifying Customer Needs from User-Generated Content

We evaluate user-generated content as a source of customer needs and propose and test a machine-learning approach for identifying customer needs more efficiently.
Synthesis of benzofuranones related to diazonamide via an intramolecular Pummerer reaction

Abstract Treatment of in situ generated 2-thiomethyl-2-chloro-2-phenylacetyl aryl esters with SnCl 4 (catalytic) resulted in the formation of the corresponding 3-thiomethylbenzofuran-2-ones.
2,4,6-Trichloropyrimidine. Reaction with sodium amide

The first reaction between 2,4,6-trichloropyrimidine 1 and anionic nitrogen nucleophiles is described. Treatment of 1 with one equivalent of sodium amide gave mixtures of 4-amino-2,6-dichloropyrimidine 2 and 2-amino-4,6-dichloropyrimidine 3. Additional quantities of sodium amide failed to provide either diamino- or triaminopyrimidines. Instead, the strongly basic nature of sodium amide led to higher molecular products that were not characterized.
Cobalt-catalyzed homocoupling of terminal alkynes: synthesis of 1,3-diynes

Abstract Homocoupling of terminal alkynes proceeds using Co2(CO)8 pretreated with phenanthroline to give good yields of 1,3-diynes under mild conditions.
Theoretical Studies of B2Lin (n = 1−4)

Structures and energies of the binary B2Lin (n = 1−4) clusters are predicted with the HF, MP2, and B3LYP methods using the 6-31G(d) basis set, including energy evaluations at G2MP2 and CBS-Q and the larger 6-311+G(2d) basis set for B3LYP. All systems except B2Li4 are also computed with the CASSCF method because of spin contamination for several of the open-shell systems. These were followed by energy evaluations with multiconfigurational perturbation theory. The global B2Li minimum has a C2v triangular form of which the 2B1 state is 13 kcal/mol more stable than the 2A1 state. A bent double Li-bridged structure (C2v) is the global B2Li2 minimum with a 2.0 kcal/mol inversion barrier. The global minimum for B2Li3 is a triple Li-bridged propellane-like structure (D3h), and for B2Li4 it is the quadruple Li-bridged structure (D4h). All these structure have a high degree of ionicity, but in B2Li4 stabilization through LiLi interactions also become important. Structural patterns for the isomers of these clusters ...
A diastereoselective synthesis of (S,S)-α-fluoro-2,2-dimethyl-1,3-dioxolane-4-propanoic acid methyl ester, a key intermediate for the preparation of anti-HIV effective fluorodideoxynucleosides

(S,S)-α-fluoro-2,2-dimethyl-1,3-dioxolane-4-propanoic acid methyl ester (10), a key intermediate for the preparation of anti-HIV active 9-(2,3-dideoxy-2-fluoro-β-D-threo-pentofuranosyl)adenine (1, FddA) and 1-(2,3-dideoxy-2-fluoro-β-D-threo-pentofuranosyl)cytosine (2, FddC) was prepared via the diastereoselective fluorination of the chiral imide enolate obtained from 8 with N-fluorobenzenesulfonimide. The overall yield of 10 from the readily available 1,2:5,6-di-O-isopropylidene-D-mannitol was 25% (de 93%).
NOVEL METHODOLOGY FOR THE SYNTHESIS OF ESTROGENIC AND ANTIESTROGENIC ISOFLAV-3-ENES

Abstract A novel and selective method for the introduction of substituents at the 2-position of the isoflav-3-ene nucleus, utilising readily available 3-arylcoumarins as starting materials, is described. Thus, addition of a Grignard reagent to the corresponding phenyl acetal provided the desired 2-alkyl-, alkenyl-, or arylisoflav-3-enes. These compounds interact strongly with the estrogen receptor and show estrogenic or antiestrogenic effects depending upon the nature ol the 2-substituent.
High throughput ANI analysis of 90K prokaryotic genomes reveals clear species boundaries.

A fundamental question in microbiology is whether there is continuum of genetic diversity among genomes, or clear species boundaries prevail instead. Whole-genome similarity metrics such as Average Nucleotide Identity (ANI) help address this question by facilitating high resolution taxonomic analysis of thousands of genomes from diverse phylogenetic lineages. To scale to available genomes and beyond, we present FastANI, a new method to estimate ANI using alignment-free approximate sequence mapping. FastANI is accurate for both finished and draft genomes, and is up to three orders of magnitude faster compared to alignment-based approaches. We leverage FastANI to compute pairwise ANI values among all prokaryotic genomes available in the NCBI database. Our results reveal clear genetic discontinuity, with 99.8% of the total 8 billion genome pairs analyzed conforming to >95% intra-species and <83% inter-species ANI values. This discontinuity is manifested with or without the most frequently sequenced species, and is robust to historic additions in the genome databases. Average Nucleotide Identity (ANI) is a robust and useful measure to gauge genetic relatedness between two genomes. Here, the authors develop FastANI, a method to compute ANI using alignment-free approximate sequence mapping, and show 95% ANI is an accurate threshold for demarcating prokaryotic species by analyzing about 90,000 prokaryotic genomes.
Asymmetric total synthesis of nigerone.

An enantioselective synthesis of the chiral bisnaphthopyrone natural product nigerone is reported. The key step was an eight-step isomerization process to form the final natural product. The isomer...
Synthesis of the sex pheromone of the obscure mealybug, the first example of a new class of monoterpenoids

Abstract A diastereoselective synthesis of (1 R ∗ ,2 R ∗ ,3 S ∗ )-1-acetoxymethyl-2,3,4,4-tetramethylcyclopentane, the sex pheromone of the obscure mealybug Pseudococcus viburni , is described. Key steps included the polyphosphoric acid-catalyzed cyclization of isobutyl methacrylate to form the core five-membered ring, and diastereoselective quenching of an enolate intermediate to give the thermodynamically less favored cis orientation of vicinal methyl groups in a cyclopentanone intermediate.
Optimization of triangular networks with spatial constraints

A common representation of a three dimensional object in computer applications, such as graphics and design, is in the form of a triangular mesh. In many instances, individual or groups of triangle...
Synthesis of 5-hydroxyquinolines

A series of 5-hydroxyquinolines has been prepared via the Skraup reaction. Several regioisomers were made either by selective displacement of a leaving group or by using a bromo substituent as a blocking group. The bromo group was found to be an excellent blocking group due to its stability during the Skraup reaction and easy removal thereafter. Halides at the 5-position of quinoline were found to be much more reactive than those at the 7- and 8-positions. Finally, we have also found a unique method to reduce the pyridyl ring on quinolines, leaving a halogen substituent untouched.
Potential DNA bis-intercalating agents. Bridged bis-(6-chloropurines) and related compounds

Two bis-(6-chloropurines) bridged by conformationally restricted tethers were synthesized as potential DNA bis-intercalating agents. Reduction of 4,6-dichloro-5-nitropyrimidine (1) afforded 5-amino-4,6-dichloropyrimidine (2) which was then used as the starting material. Reaction of 2 with 4,4′-diaminodiphenylmethane (3) and bis-(4-aminophenyl) ether (4) yielded bis-[4-(N-5-amino-4-chloro-6-pyrimidyl)aminophenyl]methane (5) and bis-[4-(N-5-amino-4-chloro-6-pyrimidyl)aminophenyl] ether (6), respectively. Acid-catalyzed condensation of the above pyrimidines, 5 and 6, with triethyl orthoformate in N,N-dimethylacetamide gave bis-[4-(6-chloro-9-purinyl)phenyl]methane (7) and bis-[4-(6-chloro-9-purinyl)phenyl] ether (8). The spectral data on the new compounds will be discussed.
Real time time-dependent density functional theory using higher order finite-element methods

We present a computationally efficient approach to solve the time-dependent Kohn-Sham equations in real time using higher order finite-element spatial discretization, applicable to both pseudopotential and all-electron calculations. To this end, we develop an a priori mesh adaption technique, based on the semidiscrete (discrete in space but continuous in time) error estimate on the time-dependent Kohn-Sham orbitals, to construct an efficient finite-element discretization. Subsequently, we obtain the full-discrete error estimate to guide our choice of the time step. We employ spectral finite elements along with special reduced order quadrature to render the overlap matrix diagonal, thereby simplifying the inversion of the overlap matrix that features in the evaluation of the discrete time-evolution operator. We use the second-order Magnus operator as the time-evolution operator, wherein the action of the discrete Magnus operator, expressed as exponential of a matrix, on the Kohn-Sham orbitals is obtained efficiently through an adaptive Lanczos iteration. We observe close to optimal rates of convergence of the dipole moment with respect to spatial and temporal discretization, for both pseudopotential and all-electron calculations. We demonstrate a staggering 100-fold reduction in the computational time afforded by higher order finite elements over linear finite elements, for both pseudopotential and all-electron calculations. Further, for similar level of accuracy, we obtain significant computational savings by our approach as compared to state-of-the-art finite-difference methods. We also demonstrate the competence of higher order finite elements for all-electron benchmark systems. Lastly, we observe good parallel scalability of the proposed method on many hundreds of processors.
Yield and selectivity enhancement by trimethylsilyl chloride in the conjugate addition of stabilized organolithiums

Abstract The yield and selectivity in the conjugate addition of some stabilized organolithiums to α,β-unsaturated carbonyl compounds, especially easily polymerized ones, are increased in the presence of trimethylsilyl chloride, alone or in combination with hexamethylphosphoric triamide. E-silyl enol ethers bearing the versatile phenylthio group are obtained prior to hydrolysis. Some synthetic uses are demonstrated.
The direct aldol reaction using bifunctional catalysts

Abstract In this paper, we describe an approach to the direct aldol reaction using a bifunctional catalyst containing Lewis acidic and basic functional groups. To achieve this novel means of catalysis we have developed new tertiary amine–zinc catalysts, which perform the aldol reaction between acetone and p -nitrobenzaldehyde.
Fungi exposed to chronic nitrogen enrichment are less able to decay leaf litter

Saprotrophic fungi are the primary decomposers of plant litter in temperate forests, and their activity is critical for carbon (C) and nitrogen (N) cycling. Simulated atmospheric N deposition is associated with reduced fungal biomass, shifts in fungal community structure, slowed litter decay, and soil C accumulation. Although rarely studied, N deposition may also result in novel selective pressures on fungi, affecting evolutionary trajectories. To directly test if long-term N enrichment reshapes fungal responses to N, we isolated decomposer fungi from a long-term (28 year) N addition experiment and used a common garden approach to compare growth rates and decay abilities of isolates from control and N amended plots. Both growth and decay were significantly altered by long-term exposure to N enrichment. Changes in growth rates were idiosyncratic, as different species grew either more quickly or more slowly after exposure to N, but litter decay by N isolates was consistent and generally lower compared to control isolates of the same species, a response not readily reversed when N isolates were grown in control (low N) environments. Changes in fungal responses accompany and perhaps drive previously observed N-induced shifts in fungal diversity, community composition, and litter decay dynamics. This article is protected by copyright. All rights reserved.
High Pressure Synthesis of Alkali Metal-Transition Metal Compounds

New compounds in the K-Ag, K-Ni, and K-Pd systems have been found to form at high pressure. Such compounds are of interest because it is possible that potassium may be incorporated into Earth's core, which is composed primarily of the transition metal iron. Furthermore, unusual crystal and electronic structures may result because of the novel chemical composition of the alkali metal-transition metal compounds.
A simple, stereoselective synthesis of ketomethylene dipeptide isosteres

Abstract An exceedingly simple, general, and stereoselective method for the preparation of ketomethylene dipeptide isosteres (5-(carbobenzyloxyamino)-2-alkyl-γ-ketoesters) from Cbz-protected amino acids and scalemic 2-triflyloxy esters has been developed. The method is short (three steps), efficient, and highly diastereoselective and enantioselective.
Cyclocarbopalladation of alkynes: a stereoselective method for preparing dibenzoxapine containing tetrasubstituted exocyclic alkenes.

A palladium-catalyzed cascade carbometalation-cross coupling of alkyne route was developed for the preparation of tetrasubstituted exocyclic alkenes with high stereo- and regiocontrol. The effectiv...
Distinguishing signal from autofluorescence in cryogenic correlated light and electron microscopy of mammalian cells.

In cryogenic correlated light and electron microscopy (cryo-CLEM), frozen targets of interest are identified and located on EM grids by fluorescence microscopy and then imaged at higher resolution by cryo-EM. Whilst working with these methods, we discovered that a variety of mammalian cells exhibit strong punctate autofluorescence when imaged under cryogenic conditions (80 K). Autofluorescence originated from multilamellar bodies (MLBs) and secretory granules. Here we describe a method to distinguish fluorescent protein tags from these autofluorescent sources based on the narrower emission spectrum of the former. The method is first tested on mitochondria and then applied to examine the ultrastructural variability of secretory granules within insulin-secreting pancreatic beta-cell-derived INS-1E cells.
Theoretical Study of Structural and Vibrational Properties of Al3N3, Ga3N3, and In3N3

We report the results of a theoretical study of the nitride trimers (i.e., M3N3 with M = Al, Ga, and In) focusing on their structure, stability, and vibrational properties. The calculated results reveal a distinct structural difference between the most stable isomers of Al and those of Ga and In, which can be explained in terms of the evolution of the relative strengths of metal−nitrogen and metal−metal bonds in going from Al to Ga to In. It is also shown that the strength of the nitrogen−nitrogen bond still dominates the preferred fragmentation path for these clusters and that fragmentation occurs at a lower energy than ionization. Assignments to the frequencies of the various normal modes are made in terms of those of the MN monomers (Al3N3) or in terms of those of weakly bonded (M3)+ and (N3)- subunits (Ga3N3 and In3N3).
Novel co-culture plate enables growth dynamic-based assessment of contact-independent microbial interactions

Interactions between microbes are central to the dynamics of microbial communities. Understanding these interactions is essential for the characterization of communities, yet challenging to accomplish in practice. There are limited available tools for characterizing diffusion-mediated, contact-independent microbial interactions. A practical and widely implemented technique in such characterization involves the simultaneous co-culture of distinct bacterial species and subsequent analysis of relative abundance in the total population. However, distinguishing between species can be logistically challenging. In this paper, we present a low-cost, vertical membrane, co-culture plate to quantify contact-independent interactions between distinct bacterial populations in co-culture via real-time optical density measurements. These measurements can be used to facilitate the analysis of the interaction between microbes that are physically separated by a semipermeable membrane yet able to exchange diffusible molecules. We show that diffusion across the membrane occurs at a sufficient rate to enable effective interaction between physically separate cultures. Two bacterial species commonly found in the cystic fibrotic lung, Pseudomonas aeruginosa and Burkholderia cenocepacia, were co-cultured to demonstrate how this plate may be implemented to study microbial interactions. We have demonstrated that this novel co-culture device is able to reliably generate real-time measurements of optical density data that can be used to characterize interactions between microbial species.
Maximum entropy methods for extracting the learned features of deep neural networks

New architectures of multilayer artificial neural networks and new methods for training them are rapidly revolutionizing the application of machine learning in diverse fields, including business, social science, physical sciences, and biology. Interpreting deep neural networks, however, currently remains elusive, and a critical challenge lies in understanding which meaningful features a network is actually learning. We present a general method for interpreting deep neural networks and extracting network-learned features from input data. We describe our algorithm in the context of biological sequence analysis. Our approach, based on ideas from statistical physics, samples from the maximum entropy distribution over possible sequences, anchored at an input sequence and subject to constraints implied by the empirical function learned by a network. Using our framework, we demonstrate that local transcription factor binding motifs can be identified from a network trained on ChIP-seq data and that nucleosome positioning signals are indeed learned by a network trained on chemical cleavage nucleosome maps. Imposing a further constraint on the maximum entropy distribution also allows us to probe whether a network is learning global sequence features, such as the high GC content in nucleosome-rich regions. This work thus provides valuable mathematical tools for interpreting and extracting learned features from feed-forward neural networks.