42 research outputs found

    Chan–Lam amination of secondary and tertiary benzylic boronic esters

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    We report a Chan–Lam coupling reaction of benzylic and allylic boronic esters with primary and secondary anilines to form valuable alkyl amine products. Both secondary and tertiary boronic esters can be used as coupling partners, with mono-alkylation of the aniline occurring selectively. This is a rare example of a transition-metal-mediated transformation of a tertiary alkylboron reagent. Initial investigation into the reaction mechanism suggests that transmetalation from B to Cu occurs through a single-electron, rather than a two-electron process

    Edge Dynamics in Quantum Hall Bilayers II: Exact Results with Disorder and Parallel Fields

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    We study edge dynamics in the presence of interlayer tunneling, parallel magnetic field, and various types of disorder for two infinite sequences of quantum Hall states in symmetric bilayers. These sequences begin with the 110 and 331 Halperin states and include their fractional descendants at lower filling factors; the former is easily realized experimentally while the latter is a candidate for the experimentally observed quantum Hall state at a total filling factor of 1/2 in bilayers. We discuss the experimentally interesting observables that involve just one chiral edge of the sample and the correlation functions needed for computing them. We present several methods for obtaining exact results in the presence of interactions and disorder which rely on the chiral character of the system. Of particular interest are our results on the 331 state which suggest that a time-resolved measurement at the edge can be used to discriminate between the 331 and Pfaffian scenarios for the observed quantum Hall state at filling factor 1/2 in realistic double-layer systems.Comment: revtex+epsf; two-up postscript at http://www.sns.ias.edu/~leonid/ntwoup.p

    Amyloid binding and beyond: a new approach for Alzheimer's disease drug discovery targeting Aβo–PrPC binding and downstream pathways

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    Amyloid β oligomers (Aβo) are the main toxic species in Alzheimer's disease, which have been targeted for single drug treatment with very little success. In this work we report a new approach for identifying functional Aβo binding compounds. A tailored library of 971 fluorine containing compounds was selected by a computational method, developed to generate molecular diversity. These compounds were screened for Aβo binding by a combined 19F and STD NMR technique. Six hits were evaluated in three parallel biochemical and functional assays. Two compounds disrupted Aβo binding to its receptor PrPC in HEK293 cells. They reduced the pFyn levels triggered by Aβo treatment in neuroprogenitor cells derived from human induced pluripotent stem cells (hiPSC). Inhibitory effects on pTau production in cortical neurons derived from hiPSC were also observed. These drug-like compounds connect three of the pillars in Alzheimer's disease pathology, i.e. prion, Aβ and Tau, affecting three different pathways through specific binding to Aβo and are, indeed, promising candidates for further development

    An Observational Overview of Solar Flares

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    We present an overview of solar flares and associated phenomena, drawing upon a wide range of observational data primarily from the RHESSI era. Following an introductory discussion and overview of the status of observational capabilities, the article is split into topical sections which deal with different areas of flare phenomena (footpoints and ribbons, coronal sources, relationship to coronal mass ejections) and their interconnections. We also discuss flare soft X-ray spectroscopy and the energetics of the process. The emphasis is to describe the observations from multiple points of view, while bearing in mind the models that link them to each other and to theory. The present theoretical and observational understanding of solar flares is far from complete, so we conclude with a brief discussion of models, and a list of missing but important observations.Comment: This is an article for a monograph on the physics of solar flares, inspired by RHESSI observations. The individual articles are to appear in Space Science Reviews (2011

    Computer-supported work in partially distributed and co-located teams: the influence of mood feedback

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    This article examines the influence of mood feedback on different outcomes of teamwork in two different collaborative work environments. Employing a 2 x 2 between-subjects design, mood feedback (present vs. not present) and communication mode (face-to-face vs. video conferencing) were manipulated experimentally. We used a newly developed collaborative communication environment, called EmotiBoard, which is a large vertical interactive screen, with which team members can interact in a face-to-face discussion or as a spatially distributed team. To support teamwork, this tool provides visual feedback of each team member’s emotional state. Thirty-five teams comprising 3 persons each (with a confederate in each team) completed three different tasks, measuring mood, performance, subjective workload, and team satisfaction. Results indicated that the evaluation of the other team members’ emotional state was more accurate when the mood feedback was presented. In addition, mood feedback influenced team performance positively in the video conference condition and negatively in the face-to-face condition. Furthermore, participants in the video conference condition were more satisfied after task completion than participants in the face-to-face condition. Findings indicate that the mood feedback toolis helpful for teams to gain a more accurate understanding of team members’ emotional states in different work situations

    Non-binary and binary gender identity in Australian trans and gender diverse individuals

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    Published online: 13 April 2020Many trans and gender diverse (TGD) people have gender identities that are not exclusively male or female but instead fall in-between or outside of the gender binary (non-binary). It remains unclear if and how those with non-binary gender identity differ from TGD individuals with binary identities. We aimed to understand the sociodemographic and mental health characteristics of people with non-binary identities compared with binary TGD identities. We performed a retrospective audit of new consultations for gender dysphoria between 2011 and 2016 in three clinical settings in Melbourne, Australia; (1) Equinox Clinic, an adult primary care clinic, (2) an adult endocrine specialist clinic, and (3) the Royal Children's Hospital, a child and adolescent specialist referral clinic. Age (grouped by decade), gender identity, sociodemographic, and mental health conditions were recorded. Of 895 TGD individuals, 128 (14.3%) had a non-binary gender. Proportions differed by clinical setting; 30.4% of people attending the adult primary care clinic, 7.4% attending the adult endocrine specialist clinic, and 8.0% attending the pediatric clinic identified as non-binary. A total of 29% of people in the 21-30-year-old age-group had a non-binary gender identity, higher than all other age-groups. Compared to TGD people with a binary gender identity, non-binary people had lower rates of gender-affirming interventions, and a higher prevalence of depression, anxiety, and illicit drug use. Tailoring clinical services to be inclusive of non-binary people and strategies to support mental health are required. Further research to better understand health needs and guide evidence-based gender-affirming interventions for non-binary people are needed.Ada S. Cheung, Shalem Y. Leemaqz, John W. P. Wong, Denise Chew, Olivia Ooi, Pauline Cundill ... et al

    Concept Maps: Integrating Knowledge and Information Visualization

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    Abstract. Information visualization has been a research topic for many years, leading to a mature field where guidelines and practices are well established. Knowledge visualization, in contrast, is a relatively new area of research that has received more attention recently due to the interest from the business community in Knowledge Management. In this paper we present the CmapTools software as an example of how concept maps, a knowledge visualization tool, can be combined with recent technology to provide integration between knowledge and information visualizations. We show how concept map-based knowledge models can be used to organize repositories of information in a way that makes them easily browsable, and how concept maps can improve searching algorithms for the Web. We also report on how information can be used to complement knowledge models and, based on the searching algorithms, improve the process of constructing concept maps. 1 Introduction: Information and Knowledge Visualization Information visualization is a well-studied, broad topic. Since the earliest cave paintings
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