cssi/SciSciGPT-SciSciNet huggingface dataset:
Interactive Data Exploration with Smart Drill-Down

We present smart drill-down , an operator for interactively exploring a relational table to discover and summarize “interesting” groups of tuples. Each group of tuples is described by a rule . For instance, the rule $(a, b, \star, 1000)$ tells us that there are 1,000 tuples with value $a$ in the first column and $b$ in the second column (and any value in the third column). Smart drill-down presents an analyst with a list of rules that together describe interesting aspects of the table. The analyst can tailor the definition of interesting, and can interactively apply smart drill-down on an existing rule to explore that part of the table. We demonstrate that the underlying optimization problems are NP-Hard , and describe an algorithm for finding the approximately optimal list of rules to display when the user uses a smart drill-down, and a dynamic sampling scheme for efficiently interacting with large tables. Finally, we perform experiments on real datasets on our experimental prototype to demonstrate the usefulness of smart drill-down and study the performance of our algorithms.
Obstacle-Aware Clock-Tree Shaping During Placement

Traditional integrated circuit (IC) design flows optimize clock networks before signal-net routing are limited by the quality of register placement. Existing publications also reflect this bias and focus mostly on clock routing. The few known techniques for register placement exhibit significant limitations and do not account for recent progress in large-scale placement and obstacle-aware clock-network synthesis. In this paper, we integrate clock network synthesis within global placement by optimizing register locations. We propose: 1) obstacle-aware virtual clock-tree synthesis; 2) arboreal clock-net contraction force with virtual-node insertion, which can handle multiple clock domains and gated clocks; and 3) an obstacle-avoidance force (OAF). Our work is validated on large benchmarks with numerous macroblocks. Experimental results indicate that our software implementation, called Lopper, prunes clock-tree branches to reduce their length by 30.0%-36.6% and average total dynamic power consumption by 6.8%-11.6% versus conventional wirelength-driven approaches. SPICE-driven simulations show that our methods improve robustness of clock trees.
Co-inventor networks and knowledge production in specialized and diversified cities

Research on the US urban system has shown that metropolitan regions with more local and non‐local network ties outperform cities where economic agents are isolated. Yet, little attention is given to the character of the local knowledge base and how that influences network structure. We show that co‐inventor networks differ between cities that produce specialized and diversified knowledge. Models of tie‐formation show inventors in specialized cities value spatial proximity less and cognitive proximity more than inventors in diversified cities as they partner with non‐local inventors. These findings suggest that the influence of social networks on knowledge production is conditioned by the architecture of the local knowledge base. La investigacion sobre el sistema urbano de los EE.UU. ha demostrado que el desempeno de las regiones metropolitanas con una mayor concentracion de vinculos de redes locales y no locales supera al de las ciudades donde los agentes economicos estan aislados. Sin embargo, se presta poca atencion al caracter de la base de conocimiento local y a la forma en que esto influye en la estructura de la red. Se demuestra que las redes de co‐inventores difieren entre las ciudades que producen conocimientos especializados y diversificados. Los modelos de formacion de vinculos muestran que los inventores de las ciudades especializadas valoran menos la proximidad espacial que la proximidad cognitiva en comparacion con los inventores de ciudades diversificadas, a la hora de asociarse con inventores no locales. Estos hallazgos sugieren que la influencia de las redes sociales en la produccion de conocimiento esta condicionada por la arquitectura de la base de conocimiento local. 米国の都市システムに関する研究により、地域的と非地域的なネットワークの結合を持つ大都市の地域が、経済主体が孤立している都市よりも優れていることが示されている。しかしながら、地域のナレッジベースの特性と、それがネットワークの構造にどのように影響するかについては、ほとんど関心が向けられていない。本稿では、共同発明者のネットワークは、専門的および多様な知識を生み出す都市によって異なることを明らかにする。ネットワークの結合形成のモデルから、専門的都市における発明者は、地元以外の発明者と提携するため、多様な都市における発明者ほどには空間的近接性に価値を認めておらず、また多様な都市における発明者よりも認知的近接性に価値を認めていることが示された。これらの知見から、知識生産に対する社会的ネットワークの影響は、地域のナレッジベースの構造によって条件づけられることが示唆される。
Proceedings of the second ACM workshop on Storage security and survivability

Welcome to the Second ACM International Workshop on Storage Security and Survivability (StorageSS'06) which was held in Alexandria, Virginia, on October 30, 2006, in conjunction with the Thirteenth ACM Conference on Computer and Communications Security (CCS 2006).Storage is a complex area of research. In recent years, two major related problems in this field have emerged: security and survivability. The amount of data that is produced and stored digitally is growing at phenomenal rates, but the I/O speeds at which these massive amounts of data can be accessed is not keeping pace with this growth. At the same time, we expect data to be preserved for decades or longer. The first problem, therefore, is how to ensure that data written today remains secure for years to come: for example, preventing slow attacks on persistent stores which may take years to complete, or ensuring the use of strong yet efficient encryption technology which can last a lifetime. The second problem is survivability: ensuring that the data written today will still be readable years from now. For example, storage systems must deal with major disasters, evolution and obsolescence of data formats, and failure-prone hardware with a limited lifespan. These are challenging problems, especially given the large scale of storage and the need for truly long-term guarantees.Now in its second year, this workshop was created to help tackle these difficult problems by bringing together researchers and practitioners from industry, government, and academia across the world. One of the workshop's goals is to foster discussions that may challenge conventions, suggest forward-looking ideas, and even provoke "wild" ideas that will eventually lead to truly novel, ground-breaking technologies.StorageSS'06 attracted sixteen high-quality submissions, each of which received between three and five reviews, with at least three reviews from program committee (PC) members. The PC met for several hours to discuss the papers and, after a lively meeting, eleven papers were accepted. We are very happy with the final workshop program, which contains an excellent mix of thought-provoking papers providing good coverage of both security and survivability. We are particularly proud that many papers came from well-established researchers and practitioners in the field; this is quite an achievement for only a two-year old workshop.
Construction of Incoherent Feedforward Loop Circuits in a Cell-Free System and in Cells

Cells utilize transcriptional regulation networks to respond to environmental signals. Network motifs, such as feedforward loops, play essential roles in these regulatory networks. In this work, we construct two different functional and modular incoherent type 1 feedforward loop circuits in a cell-free transcription–translation system and in cells. With the help of mathematical modeling and the cell-free system, we can streamline the design–build–test cycles of the circuits, in which we characterize and optimize these circuits in vitro to confirm that they function as expected before implementing them in vivo. We show that the performance of these circuits from in vitro studies closely recapitulates those from in vivo experiments. We demonstrate that these feedforward loops show dynamic response and pulse-like behavior both in vitro and in vivo. These novel feedforward loop network motifs can be incorporated in more complicated biological circuits as detectors or responders.
Praxis of Reproducible Computational Science

Among the top challenges of reproducible computational science are the following: 1) creation, curation, usage, and publication of research software; 2) acceptance, adoption, and standardization of open-science practices; and 3) misalignment with academic incentive structures and institutional processes for career progression. I will mainly address the first two here, proposing a praxis of reproducible computational science.
The transposition of the Patients’ Rights Directive in Finland—Difficulties encountered

The Directive on the application on patient rights' in cross-border healthcare (2011/24/EC) was transposed in Finland by the Act on Cross-Border Health Care (1201/2013), which entered into force on 1 January 2014. A new reimbursement model for cross-border health care costs was designed. The Finnish legislator considered the chosen reimbursement model to correspond both with the aims of the Directive as well as to the functioning of the national health care scheme. The European Commission, however, initiated the first infringement procedure against Finland already in January 2014. In spring 2015, the Government launched a Regional government, health and social services reform, which would fundamentally transform the organizing, production and financing of health care services in Finland. Consequently a Government bill (HE 68/2017 vp) to change the existing reimbursement model for cross-border health care costs was delivered to the Parliament on 1 June 2017. In this article, Finland's implementation process of the Directive is reviewed. Special attention is drawn to the argumentation concerning the reimbursements of cross-border health care costs. The differences of views on reimbursements can generally illustrate the conflicting objectives to expand access to cross-border health care services and to ensure financial sustainability of states thereof.
Social Networks for Human Papillomavirus Vaccine Advice Among African American Parents.

Abstract Purpose Despite that human papillomavirus (HPV) vaccination could prevent ∼90% of HPV-associated cancers, only 65.5% of American adolescents initiate vaccination. African Americans have the highest prevalence of morbidity and mortality from HPV-associated cancers. Mounting evidence suggests that advice from social contacts is associated with vaccine acceptance. The present study examines the associations of social processes with HPV vaccine refusal among African American parents. Methods A cross-sectional survey was conducted among African American parents of children aged 10–12 years before a health-care visit at which HPV vaccine was offered by the health-care provider. Data from the 353 parents who named at least one social contact who advised them about vaccines were included in these analyses. Results Only 54.4% of the participants consented to HPV vaccination for their children. On average, parents had 2 to 3 social contacts who provided vaccine advice. Vaccine advice networks were generally dense, family-centric, and homophilous. Slightly over 80% of all parents trusted family members and friends for vaccine advice “some” or “a lot.” Controlling for sociodemographic characteristics and reason for the health-care visit, perceived high exposure to anti-HPV vaccine viewpoints and low exposure to pro-HPV vaccine viewpoints were both associated with HPV vaccine refusal (adjusted odds ratio = 1.5, 95% confidence interval = 1.01, 2.3, and adjusted odds ratio = 1.7, 95% confidence interval = 1.2, 2.6, respectively). Conclusions Social processes may be associated with HPV vaccine refusal among African American parents. Interventions designed to educate African American parents about HPV vaccine to increase uptake should consider leveraging vaccine advice networks for greater impact.
Envisioning health equity for American Indian/Alaska Natives: a unique HIT opportunity

The Indian Health Service provides care to remote and under-resourced communities in the United States. American Indian/Alaska Native patients have some of the highest morbidity and mortality among any ethnic group in the United States. Starting in the 1980s, the IHS implemented the Resource and Patient Management System health information technology (HIT) platform to improve efficiency and quality to address these disparities. The IHS is currently assessing the Resource and Patient Management System to ensure that changing health information needs are met. HIT assessments have traditionally focused on cost, reimbursement opportunities, infrastructure, required or desired functionality, and the ability to meet provider needs. Little information exists on frameworks that assess HIT legacy systems to determine solutions for an integrated rural healthcare system whose end goal is health equity. This search for a next-generation HIT solution for a historically underserved population presents a unique opportunity to envision and redefine HIT that supports health equity as its core mission.
Synthesis of polysubstituted anilines using the Diels-Alder reaction of methyl 5-aminofuroate

Methyl 5-aminofuroate undergoes a facile [4+2]-cycloaddition with a variety of dienophiles to afford ring opened cycloadducts which are readily dehydrated using BF3·OEt2 to give polysubstituted anilines.
α-Amination of Phosphonates: A Direct Synthesis of α-Amino Phosphonic Acids and Their Derivatives

A direct approach to access important α-amino phosphonic acids and their derivatives through the formation of C–N bonds is described. Several α-amination reactions of phosphonates that involve electrophilic aminating agents are reviewed. A recent development is highlighted in which an acyclic or cyclic amine is introduced into the α-position of a phosphonate in one step through deprotonative formation of an α-zincate followed by copper-catalyzed amination with an O-acylhydroxylamine.
ASYMMETRIC SYNTHESES WITH CATALYTIC ENANTIOSELECTIVE METAL CARBENE TRANSFORMATIONS

Asymmetric catalysis of metal carbene transformations with unique chiral dirhodium(II) carboxamides provides highly enantioselective and diastereoselective synthesesvia cyclopropanation, cyclopropenation, and carbon-hydrogen insertion reactions of diazoesters and diazoamides. Constructed from a dirhodium(II) core with bridging pyrrolidone, oxazolidinone, or imidazolidinone ligands, these catalysts are especially effective for intramolecular transformations that occur in high yield with greater than 90 % enantiomeric excess (ee) and high diastereocontrol.
Human Papillomavirus 16 E2 Regulates Keratinocyte Gene Expression Relevant to Cancer and the Viral Life Cycle

Human papillomaviruses (HPVs) are causative agents in ano-genital and oropharyngeal cancers. The virus must reprogram host gene expression to promote infection, and E6 and E7 contribute to this via the targeting of cellular transcription factors, including p53 and pRb, respectively. The HPV16 E2 protein regulates host gene expression in U2OS cells, and in this study, we extend these observations into telomerase reverse transcriptase (TERT) immortalized oral keratinocytes (NOKs) that are capable of supporting late stages of the HPV16 life cycle. We observed repression of innate immune genes by E2 that are also repressed by the intact HPV16 genome in NOKs. Transcriptome sequencing (RNA-seq) data identified 167 up- and 395 downregulated genes by E2; there was a highly significant overlap of the E2-regulated genes with those regulated by the intact HPV16 genome in the same cell type. Small interfering RNA (siRNA) targeting of E2 reversed the repression of E2-targeted genes. The ability of E2 to repress innate immune genes was confirmed in an ano-genital immortalized keratinocyte cell line, N/Tert-1. We present the analysis of data from The Cancer Genome Atlas (TCGA) for HPV16-positive and -negative head and neck cancers (HNC) suggesting that E2 plays a role in the regulation of the host genome in cancers. Patients with HPV16-positive HNC with a loss of E2 expression exhibited a worse clinical outcome, and we discuss how this could, at least partially, be related to the loss of E2 host gene regulation.IMPORTANCE Human papillomavirus 16 (HPV16)-positive tumors that retain expression of E2 have a better clinical outcome than those that have lost E2 expression. It has been suggested that this is due to a loss of E2 repression of E6 and E7 expression, but this is not supported by data from tumors where there is not more E6 and E7 expression in the absence of E2. Here we report that E2 regulates host gene expression and place this regulation in the context of the HPV16 life cycle and HPV16-positive head and neck cancers (the majority of which retain E2 expression). We propose that this E2 function may play an important part in the increased response of HPV16-positive cancers to radiation therapy. Therefore, host gene regulation by E2 may be important for promotion of the HPV16 life cycle and also for the response of HPV16-positive tumors to radiation therapy.
Tandem cyclopropylcarbinyl/oxiranylcarbinyl radical rearrangements: An entry into the prostaglandin B1 series

Abstract A tandem radical fragmentation of a cyclopropylcarbinyl/oxiranylcarbinyl system leads to the PGB 1 series of prostaglandins. Control of cyclopropane bond fragmentation as a function of C 2 substitution in bicyclo[3.1.0]hexanylcarbinyl radicals is presented.
The formation of 2,3-disubstituted thiazolidin-4-ones from S-α'-aminomercaptoacetic acid derivatives

Variously substituted N-benzylidineanilines rapidly react with thioglycolic acid to generate S-α'-aminomercaptoacetic acid derivatives. The latter subsequently cyclize to the corresponding 2,3-diarylthiazolidin-4-ones. Kinetics for the first order cyclization reaction in the solvents toluene, carbon tetrachloride and nitrobenzene have been obtained over the temperature range 333 K to 383 K and are in accord with a neutral, but geometrically complex transition state.
Optimal features for auditory categorization

Humans and vocal animals use vocalizations to communicate with members of their species. A necessary function of auditory perception is to generalize across the high variability inherent in vocalization production and classify them into behaviorally distinct categories ('words' or 'call types'). Here, we demonstrate that detecting mid-level features in calls achieves production-invariant classification. Starting from randomly chosen marmoset call features, we use a greedy search algorithm to determine the most informative and least redundant features necessary for call classification. High classification performance is achieved using only 10-20 features per call type. Predictions of tuning properties of putative feature-selective neurons accurately match some observed auditory cortical responses. This feature-based approach also succeeds for call categorization in other species, and for other complex classification tasks such as caller identification. Our results suggest that high-level neural representations of sounds are based on task-dependent features optimized for specific computational goals.
Taking Advantage of Gold’s Electronegativity in R4Mn3–xAu10+x (R = Gd or Y; 0.2 ≤ x ≤ 1)

Ternary R4Mn3–xAu10+x (R = Gd or Y; 0.2 ≤ x ≤ 1) compounds have been synthesized and characterized using single-crystal X-ray diffraction. The structure is a ternary variant of orthorhombic Zr7Ni10 (oC68, space group Cmca) and is isostructural with Ca4In3Au10. The structure contains layers of Mn-centered rectangular prisms of gold (Mn@Au8), interbonded via Au atoms in the b-c plane, and stacked in a hexagonal close packed arrangement along the a direction. These layers are bonded via additional Mn atoms along the a direction. The rare-earth metals formally act as cations and fill the rest of the space. The structure could also be described as sinusoidal layers of gold atoms, which are interconnected through Au–Au bonds. The magnetic characteristics of both compounds reveal the presence of nearly localized Mn magnetic moments. Magnetization M measurements of Y4Mn2.8Au10.2 versus temperature T and applied magnetic field H demonstrate the dominance of antiferromagnetic (AFM) interactions in this compound and...
The first reported anionic oxy retro-ene reaction.

Treatment of the diol 6 with KH and 18-C-6 at room temperature gives the cyclopentenone 7 in good yields. Mechanistic analysis reveals that this is the first case of an anionic oxy retro-ene reaction followed by a tandem intramolecular aldol condensation.
Preparation, structural characterization, and acid-catalyzed isomerization of 3-, 7-, and 9-benzyl-6-benzylthiopurines

Benzylation of 6-benzylthiopurine was examined. Structural assignments of the products were determined by 1-D and 2-D nmr spectroscopy (HMQC, HMBC, and nOe). In the presence of base, the isomeric N3-, N7-, and N9-benzylated products 4, 3, and 2 were isolated; however, only 9-benzyl-6-benzylthio-purine (2) was obtained in the absence of base. In the latter case, the initially formed N3- and N7-isomers were, in the presence of acid, converted to 9-benzyl-6-benzylthiopurine (2) via a 6-benzylthiopurine intermediate as evidenced by analysis of the reaction over time using reversed-phase hplc.
Group 4 metals in polyketide synthesis: a convergent strategy for the synthesis of polypropionate-derived (E,E)-trisubstituted 1,3-dienes.

A convergent Group 4 metal-mediated coupling process is described for the synthesis of polypropionate-derived (E,E)-1,3-dienes. Both the stereochemistry of the internal alkyne and the presence/absence of a tethered alkoxide on this π-component were found to play critical roles in dictating the regiochemical course of these reactions.
An organocascade approach to α,α-chlorofluoroalcohols

Fluorinated, tetrasubstituted, carbon stereocenters are challenging to install enantioselectively. gem-Chlorofluoro compounds contain a fluorinated, tetrasubstituted stereocenter, and are an entree into other such compounds. We report herein the first catalytic, enantioselective method to prepare gem-chlorofluoro compounds from unfunctionalized aldehydes. This one-pot method precludes the isolation of volatile and/or reactive α-haloaldehyde intermediates.
A convenient large scale synthesis of 2,6‐dimethyl‐4‐(trimethylstannyl)pyridine

Reaction of phosphorus oxychloride with 2,6-dimethylpyridine N-oxide hydrochloride (1) gave a mixture of 2-(chloromethyl)-6-methylpyridine (2) and 4-chloro-2,6-dimethylpyridine (3). Treatment of this mixture with triethylamine converted 2 to the quaternary salt 4 which was separated by water extraction leaving 3 which was subsequently reacted with trimethylstannyl sodium to yield 2,6-dimethyl-4-(trimethylstannyl)pyridine (6).
A one-pot, lynchpin approach to 1,4-disubstituted E,E-butadienes via multiple cyanocuprate-mediated transmetalations

Abstract Sequential transmetalation / Michael addition of E,E-1,4-bis-trimethylstannylbutadiene to enones using higher order cyanocuprates leads to products of double delivery in a 1-pot operation.
A concise, stereoselective synthesis of picenadol

Abstract A four-step stereoselective synthesis of picenadol ( 1 ) is reported, 1,3-Dimethyl-4-piperidone ( 3 ) underwent Horner-Wadsworth-Emmons reaction under conditions that did not yield double-bond isomerization, followed by a directed 1,4-addition with an aryl cuprate. Reduction and deprotection then afforded ( 1 ).
Specificity and non-specificity in the sensitized CO2-laser-induced reaction of tetrachloroethene

Previous workers have investigated the reaction of tetrachloroethene using thermal initiation and CO 2 -laser initiation via sensitizing species. In both instances, the principal product was found to be hexachlorobenzene. One group reported evidence of laser specificity in this reaction, in that BCl 3 acted as a sensitizer to produce hexachlorobenzene as the principal product, but SF 6 and BBr 3 did not. We have found that specificity is highly dependent on reaction conditions. We reproduced the previous results using similar experimental conditions, but under different conditions, we found that the specificity is lost, with all three sensitizers which we used (BCl 3 , SF 6 , and SiF 4 ) sensitizing the reaction to produce mainly hexachlorobenzene. There were some differences among the sensitizers, as, for example, the fact that SF 6 produced the most nearly pure hexachlorobenzene product.
Binge-like acquisition of α-pyrrolidinopentiophenone (α-PVP) self-administration in female rats

The synthetic cathinone α-pyrrolidinopentiophenone (α-PVP) has been associated with bizarre public behavior in users. Association of such behavior with extended binges of drug use motivates additional investigation, particularly since a prior study found that half of male rats experience a binge of exceptionally high intake, followed by sustained lower levels of self-administration during the acquisition of intravenous self-administration (IVSA) of a related drug, 3,4-methylenedioxypyrovalerone. The binge-like acquisition pattern is novel for rat IVSA; thus, the present study sought to determine if this effect generalizes to IVSA of α-PVP in female rats. Female Wistar rats were trained in IVSA of α-PVP (0.05 mg/kg/inf) in experimental chambers containing an activity wheel. Groups were trained with the wheels fixed (No-Wheel group), fixed for the initial 5 days of acquisition or free to move throughout acquisition (Wheel group). The groups were next subjected to a wheel access switch and then all animals to dose-substitution (0.0125–0.3 mg/kg/inf) with the wheels alternately fixed and free to move. Approximately half of the rats initiated their IVSA pattern with a binge day of exceptionally high levels of drug intake, independent of wheel access condition. Wheel activity was much lower in the No-Wheel group in the wheel switch post-acquisition. Dose-effect curves were similar for wheel access training groups, for binge/no binge phenotypic subgroups and were not altered with wheel access during the dose-substitution. This confirms the high reinforcer effectiveness of α-PVP in female rats and the accompanying devaluation of wheel activity as a naturalistic reward.
Automatic Identification of Support Verbs: A Step Towards a Definition of Semantic Weight

Current definitions of notions of lexical density and semantic weight are based on the division of words into closed and open classes, and on intuition. This paper develops a computationally tractable definition of semantic weight, concentrating on what it means for a word to be semantically light; the definition involves looking at the frequency of a word in particular syntactic constructions which are indicative of lightness. Verbs such as "make" and "take", when they function as support verbs, are often considered to be semantically light. To test our definition, we carried out an experiment based on that of Grefenstette and Teufel (1995), where we automatically identify light instances of these words in a corpus; this was done by incorporating our frequency-related definition of semantic weight into a statistical approach similar to that of Grefenstette and Teufel. The results show that this is a plausible definition of semantic lightness for verbs, which can possibly be extended to defining semantic lightness for other classes of words.
Anodic Amide Oxidation/Olefin Metathesis Strategies: Developing a Unified Approach to the Synthesis of Bicyclic Lactam Peptidomimetics

Abstract In connection with efforts to build constrained peptidomimetics for the endocrine hormone TRH, a general strategy for the construction of bicyclic lactam peptide building blocks has been developed. This strategy used an anodic amide oxidation to selectively functionalize proline and then an olefin metathesis to build the desired lactam constraint. The route described provides a single approach for synthesizing both fully functionalized TRH analogs having seven- and eight-membered ring lactam constraints, as well as six- and seven-membered ring lactam analogs without the sidechain on the central amino acid.
Rearrangement kinetics of spiropentylchlorocarbene, [3]triangulylchlorocarbene, and related species.

Absolute rate constants were measured for the 1,2-CH2, 1,2-cyclopropyl, and 1,2-CMe2 rearrangements of spiropentylchlorocarbene (5), [3]triangulylchlorocarbene (6), and tetramethylcyclopropylchlorocarbene (7). The factors responsible for the observed relative migratory aptitudes (cyclopropyl > CH2 > CMe2) were analyzed with the aid of electronic structure calculations.
kpLogo: positional k-mer analysis reveals hidden specificity in biological sequences

Motifs of only 1-4 letters can play important roles when present at key locations within macromolecules. Because existing motif-discovery tools typically miss these position-specific short motifs, we developed kpLogo, a probability-based logo tool for integrated detection and visualization of position-specific ultra-short motifs from a set of aligned sequences. kpLogo also overcomes the limitations of conventional motif-visualization tools in handling positional interdependencies and utilizing ranked or weighted sequences increasingly available from high-throughput assays. kpLogo can be found at http://kplogo.wi.mit.edu/.
1-Iodomethyl-3,4-diphenyl-2,6-dioxabicyclo[2.2.0]hexane: the first example of a [2.2.0] fused ketal

The preparation of 1-iodomethyl-3,4-diphenyl-2,6-dioxabicyclo[2.2.0]hexane (12) is described. This represents the first reported example of a [2.2.0] fused ketal. The key step involved the iodoetherification of a 2-methyleneoxetane 11 containing a pendant alcohol.
Fetal death certificate data quality: A tale of two U.S. counties

Abstract Purpose Describe the relative frequency and joint effect of missing and misreported fetal death certificate (FDC) data and identify variations by key characteristics. Methods Stillbirths were prospectively identified during 2006–2008 for a multisite population-based case-control study. For this study, eligible mothers of stillbirths were not incarcerated residents of DeKalb County, Georgia, or Salt Lake County, Utah, aged ≥13 years, with an identifiable FDC. We identified the frequency of missing and misreported (any departure from the study value) FDC data by county, race/ethnicity, gestational age, and whether the stillbirth was antepartum or intrapartum. Results Data quality varied by item and was highest in Salt Lake County. Reporting was generally not associated with maternal or delivery characteristics. Reasons for poor data quality varied by item in DeKalb County: some items were frequently missing and misreported; however, others were of poor quality due to either missing or misreported data. Conclusions FDC data suffer from missing and inaccurate data, with variations by item and county. Salt Lake County data illustrate that high quality reporting is attainable. The overall quality of reporting must be improved to support consequential epidemiologic analyses for stillbirth, and improvement efforts should be tailored to the needs of each jurisdiction.
GIAO-MP2/SCF/DFT Calculated NMR Chemical Shift Relationships in Isostructural Onium Ions Containing Hypercoordinate Boron, Carbon, Aluminum, and Silicon Atoms

Good linear correlations between GIAO-MP2 calculated 11B NMR chemical shifts of boronium−onium cations 1a−h and 13C NMR chemical shift of the corresponding isoelectronic carbonium−onium dications 2a−h as well as between 27Al NMR chemical shifts of the alonium−onium cations 3a−h and the 29Si NMR chemical shifts of the corresponding isoelectronic siliconium−onium dications 4a−h were found. The close relationship demonstrates that the same factors that determine the chemical shifts of the boron and aluminum nuclei also govern the chemical shifts of the carbon and silicon nuclei, respectively, within the hypercoordinate onium compounds. On the other hand, no correlation exists between 13C NMR chemical shifts of carbonium−onium dications 2a−h and the 29Si NMR chemical shifts of the corresponding siliconium−onium dications 4a−h. Furthermore, no correlation was found between 11B NMR chemical shifts of boronium−onium cations 1a−h and 27Al NMR chemical shifts of the corresponding alonium−onium cations 3a−h.
Effects of altering histone posttranslational modifications on mitotic chromosome structure and mechanics

During cell division, chromatin is compacted into mitotic chromosomes to aid faithful segregation of the genome between two daughter cells. Posttranslational modifications (PTMs) of histones alter compaction of interphase chromatin, but it remains poorly understood how these modifications affect mitotic chromosome stiffness and structure. Using micropipette-based force measurements and epigenetic drugs, we probed the influence of canonical histone PTMs that dictate interphase euchromatin (acetylation) and heterochromatin (methylation) on mitotic chromosome stiffness. By measuring chromosome doubling force (the force required to double chromosome length), we find that histone methylation, but not acetylation, contributes to mitotic structure and stiffness. We discuss our findings in the context of chromatin gel modeling of the large-scale organization of mitotic chromosomes.
NEW NONGEMINAL CYCLOPHOSPHAZENES

A series of new nongeminally-substituted cyclic phosphazenes with various substituents has been prepared via deprotonation-substitution reactions at the Me groups of both the cis and trans isomers of [(Me)(Ph)PN] 3 . Treatment of [(Me)(Ph)PN] 3 with n-BuLi followed by reaction with organic electrophilic reagents affords a variety of cyclic derivatives, [(RCH 2 )(Ph)PN] 3 , [R = Me, Cl, Br, I, (CH 2 ) 2 Br, CH 2 CH═CH 2 , SR, C(═O)OLi, C(═O)OMe, C(═O)OEt]. The structures of theses cis cyclic phosphazenes, which were obtained by x-ray diffraction, illustrate the basket-like shape of the molecules. Heating the cis and trans isomers of the parent [(Me)(Ph)PN] 3 produced mixtures of cyclic trimers and tetramers. The latter were isolated and characterized by x-ray crystallography. Nanoparticles of gold and silver were prepared by reduction of metal salts with a reducing agent in the presence of selected trimers.
Modified oxide sol-precipitation (MOSP) approach for synthesizing borophosphosilicate glasses and glass-ceramics

Synthesis of borophosphosilicate glasses and glass-ceramics was accomplished via a modified oxide sol-precipitation process (MOSP). Thermal properties of the dried precipitates were analyzed. Heat treatment of the precipitates crystallized the boron phosphate phase. The microstructure of sintered samples was characterized using electron microscopy, and the dielectric properties were measured. Dielectric measurements indicate that the sintered glass-ceramics possess dielectric constants less than 4.0 and dissipation factors less than 0.001 at a frequency of 1 MHz. 25 refs., 9 figs., 2 tabs.
A general approach to medium ring alkynes by using metathesis of cobalt hexacarbonyl containing dienes.

The assembly of medium sized rings (7−9) was achieved by using the metathesis of dienes linked by a cobalt hexacarbonyl complexed alkyne with either Grubbs' or Schrock's catalysts. The products of metathesis were subjected to transformations involving the dicobalt hexacarbonyl complexes, for example, decomplexation to liberate cyclic alkynes or Pauson−Khand reaction.
Asymmetric synthesis of 1-alkynylcyclopropane-1-carboxylates

Abstract Dirhodium tetrakis(S-(N-dodecylbenzenesulfonyl)prolinate) (Rh2S–DOSP4) catalyzed decomposition of methyl alkynyldiazoacetates in the presence of alkenes results in highly diastereoselective and enantioselective cyclopropanations.
Allosteric Role of Substrate Occupancy Toward the Alignment of P-glycoprotein Nucleotide Binding Domains.

P-glycoprotein (Pgp) is an ATP-binding cassette transporter that eliminates toxins from the cell but causes multidrug resistance in chemotherapies. The crystal structures of Pgp revealed drug-like compounds bound to an inward-facing conformation in which the energy-harnessing nucleotide binding domains (NBDs) were widely separated with no interfacial interaction. Following drug binding, inward-facing Pgp must transition to an NBD dimer conformation to achieve ATP binding and hydrolysis at canonical sites defined by both halves of the interface. However, given the high degree of flexibility shown for this transporter, it is difficult to envision how NBDs overcome entropic considerations for achieving proper alignment in order to form the canonical ATP binding site. We explored the hypothesis that substrate occupancy of the polyspecific drug-binding cavity plays a role in the proper alignment of NBDs using computational approaches. We conducted twelve atomistic molecular dynamics (MD) simulations (100–300 ns) on inward-facing Pgp in a lipid bilayer with and without small molecule substrates to ascertain effects of drug occupancy on NBD dimerization. Both apo- and drug-occupied simulations showed NBDs approaching each other compared to the crystal structures. Apo-Pgp reached a pseudo-dimerization in which NBD signature motifs for ATP binding exhibited a significant misalignment during closure. In contrast, occupancy of three established substrates positioned by molecular docking achieved NBD alignment that was much more compatible with a canonical NBD dimerization trajectory. Additionally, aromatic amino acids, known to confer the polyspecific drug-binding characteristic of the internal pocket, may also govern polyspecific drug access to the cavity. The enrichment of aromatics comprising the TM4-TM6 portal suggested a preferential pathway over the aromatic-poor TM10-TM12 for lateral drug entry from the lipid bilayer. Our study also suggested that drug polyspecificity is enhanced due to a synergism between multiple drug-domain interactions involving 36 residues identified in TM1, 5, 6, 7, 11 and 12.
On a Subposet of the Tamari Lattice

We discuss some properties of a subposet of the Tamari lattice introduced by Pallo (1986), which we call the comb poset. We show that three binary functions that are not well-behaved in the Tamari lattice are remarkably well-behaved within an interval of the comb poset: rotation distance, meets and joins, and the common parse words function for a pair of trees. We relate this poset to a partial order on the symmetric group studied by Edelman (1989). R´ esumNous discutons d'un subposet du treillis de Tamari introduit par Pallo. Nous appellons ce poset le comb poset. Nous montrons que trois fonctions binaires qui ne se comptent pas bien dans le trellis de Tamari se comptent bien dans un intervalle du comb poset : distance dans le trellis de Tamari, le supremum et l'infimum et les parsewords communs. De plus, nous discutons un rapport entre ce poset et un ordre partiel dans le groupe sym´ etrique ´´ par Edelman.
star-Porphyrazines: Synthetic, Structural, and Spectral Investigation of Complexes of the Polynucleating Porphyrazineoctathiolato Ligand

We have devised a new polynucleating porphyrinic ligand, porphyrazine-2,3,7,8,12,13,17,18-octathiolato, (pz) (S - ) 8 , the molecular structure of which may be thought of as a porphyrazine (tetraazaporphyrin) with four dithiolene moieties peripherally fused at the β-positions.
Exploring the metal-rich chemistry of the early transition elements

Abstract The early transition metals, especially Zr, Hf, Hb and Ta, exhibit a metal-rich chemistry that is often surprising in its structural and physical aspects. Unfamiliarity with this chemistry is illustrated by the discovery of several new binary compounds in the Ta-S, Ta-Se, Ta-Te, and Hf-Te systems within the past few years. Some striking differences observed between the metal-rich chalcogenides of Zr and Hf or between Nb and Ta challenge basic presumptions about the similarity of these congeneric pairs. The factors controlling the structural anisotropy of a new class of tetragonal layered compounds that includes Ta 2 Se, Ta 2− x Nb x S, Hf 3 Te 2 , and ZrZTe (Z  Si, Ge, Sn) are discussed. Strongly early-late transition intermetallic bonding leads to the formation of an expanding class of compounds that includes Ta 9 M 2 S 6 (M  Fe, Co, Ni), Ta 11 M 2 Se 8 (M  Fe, Co, Ni), Ta 8 NiSe 8 and the newly discovered hafnium tellurides, Hf 8 MTe 6 (M  Mn, Fe, Co, Ni, Ru) and Hf 5 MTe 3 (M  Fe, Co). Our efforts to dismantle solid-state Zr-halide cluster compounds is described. Ambient temperature molten salts help us achieve the controlled excision of [(Zr 6 Z)CL 18 ] n− from solid state precursors; we describe the applications of electronic and NMR spectroscopies in characterizing clusters in solution. Finally, we discuss bonding in metal-rich systems, with particular emphasis on localized bonding descriptions for metalmetal bonds in extended metal-linked networks. Such localized descriptions increase our understanding of otherwise anomalous properties and illuminate the artificiality of separate “metallic” and “covalent” bonding concepts.
Hydrothermal growth of lanthanide borosilicates: a useful approach to new acentric crystals including a derivative of cappelenite.

The reaction of barium borosilicate glasses in hydrothermal fluids with NaOH mineralizer at ca. 600–650 °C in the presence of various sources of Eu3+ ions leads to a new series of noncentrosymmetric single crystals characterized by single-crystal X-ray diffraction. Under three slightly different reaction modifications, three new Eu3+-containing noncentrosymmetric single crystals were isolated and characterized. Using a barium borosolicate glass with Eu2O3 added to the reaction mixture led to NaBaEuSi3O9 (1), which crystallizes in the noncentrosymmetric orthorhombic space group P212121 with unit cell parameters a = 5.6373(11) A, b = 11.483(2) A, and c = 12.535(2) A and consists of Eu3+ ions linked by Si3O96– rings. Using a similar glass feedstock with Eu3+ included in the starting glass composition led to the compound NaBa3Eu3Si6O20 (2), which was determined in the noncentrosymmetric polar space group Ama2 with unit cell parameters a = 14.777(3) A, b = 23.926(5) A, and c = 5.5533(11) A. It is constructed o...
Allatostatin-C/AstC-R2 Is a Novel Pathway to Modulate the Circadian Activity Pattern in Drosophila.

Summary Seven neuropeptides are expressed within the Drosophila brain circadian network. Our previous mRNA profiling suggested that Allatostatin-C (AstC) is an eighth neuropeptide and specifically expressed in dorsal clock neurons (DN1s). Our results here show that AstC is, indeed, expressed in DN1s, where it oscillates. AstC is also expressed in two less well-characterized circadian neuronal clusters, the DN3s and lateral-posterior neurons (LPNs). Behavioral experiments indicate that clock-neuron-derived AstC is required to mediate evening locomotor activity under short (winter-like) and long (summer-like) photoperiods. The AstC-Receptor 2 (AstC-R2) is expressed in LNds, the clock neurons that drive evening locomotor activity, and AstC-R2 is required in these neurons to modulate the same short photoperiod evening phenotype. Ex vivo calcium imaging indicates that AstC directly inhibits a single LNd. The results suggest that a novel AstC/AstC-R2 signaling pathway, from dorsal circadian neurons to an LNd, regulates the evening phase in Drosophila.
A practical conversion of natural physostigmine into the potent butyrylcholinesterase inhibitor N1,N8-bisnorcymserine

Abstract A rapid novel synthetic route to the potent reversible butyrylcholinesterase inhibitor (−)- N 1 , N 8 -bisnorcymserine ( 1 ) is reported from physostigmine ( 2 ) in a 20% total yield. Details on the formation of the imino-quinone 6 obtained in the oxidation of N 1 -benzylnoresermethole ( 4 ) and its conversion into N 1 -bisnoreseroline ( 7 ) are given. As expected, the product of this synthesis, ( 1 ), had identical biological activity to the same agent produced by total synthesis.
Climate Finance, Carbon Market Mechanisms and Finance "Blending" as Instruments to Support NDC Achievement under the Paris Agreement

This paper considers the impacts of "finance blending" whereby climate finance is added to international carbon markets for offset trading. The paper first discusses climate finance and the carbon market as free-standing finance solutions by high-income countries to increase mitigation in low-income countries. Climate finance solutions have advantages for high-income countries due to their greater flexibility and general efficiency. A favorable aspect of well-functioning offset markets is that all participating countries face a similar and robust carbon price. With finance blending and "all attribution to the carbon market," the market equilibrium is inefficient, as mitigation is excessive in low-income countries and too low in high-income countries. Instead, mitigation outcomes in the offset market should be attributed to the two finance types in proportion to their finance shares provided to the low-income countries through this market. When climate finance is added to the carbon market, the ambition level for emissions reductions for donor countries should be raised equivalently; otherwise, the added climate finance leads to no increase in global mitigation. When low-income country market participants have limited access to credit markets, climate finance can increase mitigation by supplying the capital required to implement efficient mitigation projects.
Cycle-by-cycle analysis of neural oscillations

We introduce a fully documented, open-source Python package, bycycle, for analyzing neural oscillations on a cycle-by-cycle basis. This approach is complementary to traditional Fourier- and Hilbert...
Every hit matters: White matter diffusivity changes in high school football athletes are correlated with repetitive head acceleration event exposure

Recent evidence of short-term alterations in brain physiology associated with repeated exposure to moderate intensity subconcussive head acceleration events (HAEs), prompts the question whether these alterations represent an underlying neural injury. A retrospective analysis combining counts of experienced HAEs and longitudinal diffusion-weighted imaging explored whether greater exposure to incident mechanical forces was associated with traditional diffusion-based measures of neural injury-reduced fractional anisotropy (FA) and increased mean diffusivity (MD). Brains of high school athletes (N = 61) participating in American football exhibited greater spatial extents (or volumes) experiencing substantial changes (increases and decreases) in both FA and MD than brains of peers who do not participate in collision-based sports (N = 15). Further, the spatial extents of the football athlete brain exhibiting traditional diffusion-based markers of neural injury were found to be significantly correlated with the cumulative exposure to HAEs having peak translational acceleration exceeding 20 g. This finding demonstrates that subconcussive HAEs induce low-level neurotrauma, with prolonged exposure producing greater accumulation of neural damage. The duration and extent of recovery associated with periods in which athletes do not experience subconcussive HAEs now represents a priority for future study, such that appropriate participation and training schedules may be developed to minimize the risk of long-term neurological dysfunction.