46,808 research outputs found

    Some identities on derangement and degenerate derangement polynomials

    Full text link
    In combinatorics, a derangement is a permutation that has no fixed points. The number of derangements of an n-element set is called the n-th derangement number. In this paper, as natural companions to derangement numbers and degenerate versions of the companions we introduce derangement polynomials and degenerate derangement polynomials. We give some of their properties, recurrence relations and identities for those polynomials which are related to some special numbers and polynomials.Comment: 12 page

    Changing cultural pathways through gender role and sexual development: A theoretical framework

    Get PDF
    Greenfield's theory linking sociodemographic change to dynamic cultural values for family interdependence versus individual independence is applied to sexual and gender role socialization and development. The theory explains how cultural pathways for sexual and gender-role development transform in concert with sociodemographic changes: urbanization, formal schooling, capitalism, and communication technologies. As environments become more urban, commercial, and technological, with more opportunities for formal education, sexual development moves away from the ideals of procreation and family responsibility and toward the ideals of personal pleasure and personal responsibility. At the same time, gender-role development moves away from the ideals of complementary and ascribed gender roles and toward chosen and equal gender roles. We present psychological, anthropological, and sociological evidence for these trends in a variety of communities undergoing social and ecological change. © 2014 by the American Anthropological Association

    Riociguat for the treatment of chronic thromboembolic pulmonary hypertension.

    Get PDF
    BACKGROUND: Riociguat, a member of a new class of compounds (soluble guanylate cyclase stimulators), has been shown in previous clinical studies to be beneficial in the treatment of chronic thromboembolic pulmonary hypertension. METHODS: In this phase 3, multicenter, randomized, double-blind, placebo-controlled study, we randomly assigned 261 patients with inoperable chronic thromboembolic pulmonary hypertension or persistent or recurrent pulmonary hypertension after pulmonary endarterectomy to receive placebo or riociguat. The primary end point was the change from baseline to the end of week 16 in the distance walked in 6 minutes. Secondary end points included changes from baseline in pulmonary vascular resistance, N-terminal pro-brain natriuretic peptide (NT-proBNP) level, World Health Organization (WHO) functional class, time to clinical worsening, Borg dyspnea score, quality-of-life variables, and safety. RESULTS: By week 16, the 6-minute walk distance had increased by a mean of 39 m in the riociguat group, as compared with a mean decrease of 6 m in the placebo group (least-squares mean difference, 46 m; 95% confidence interval [CI], 25 to 67; P<0.001). Pulmonary vascular resistance decreased by 226 dyn · sec · cm-5in the riociguat group and increased by 23 dyn · sec · cm-5in the placebo group (least-squares mean difference, -246 dyn · sec · cm-5; 95% CI, -303 to -190; P<0.001). Riociguat was also associated with significant improvements in the NT-proBNP level (P<0.001) and WHO functional class (P = 0.003). The most common serious adverse events were right ventricular failure (in 3% of patients in each group) and syncope (in 2% of the riociguat group and in 3% of the placebo group). CONCLUSIONS: Riociguat significantly improved exercise capacity and pulmonary vascular resistance in patients with chronic thromboembolic pulmonary hypertension. (Funded by Bayer HealthCare; CHEST-1 and CHEST-2 ClinicalTrials.gov numbers, NCT00855465 and NCT00910429, respectively.) Copyright © 2013 Massachusetts Medical Society

    Incremental Mutual Information: A New Method for Characterizing the Strength and Dynamics of Connections in Neuronal Circuits

    Get PDF
    Understanding the computations performed by neuronal circuits requires characterizing the strength and dynamics of the connections between individual neurons. This characterization is typically achieved by measuring the correlation in the activity of two neurons. We have developed a new measure for studying connectivity in neuronal circuits based on information theory, the incremental mutual information (IMI). By conditioning out the temporal dependencies in the responses of individual neurons before measuring the dependency between them, IMI improves on standard correlation-based measures in several important ways: 1) it has the potential to disambiguate statistical dependencies that reflect the connection between neurons from those caused by other sources (e. g. shared inputs or intrinsic cellular or network mechanisms) provided that the dependencies have appropriate timescales, 2) for the study of early sensory systems, it does not require responses to repeated trials of identical stimulation, and 3) it does not assume that the connection between neurons is linear. We describe the theory and implementation of IMI in detail and demonstrate its utility on experimental recordings from the primate visual system

    Liquid-phase synthesis of 2′-methyl-RNA on a homostar support through organic-solvent nanofiltration

    Get PDF
    Due to the discovery of RNAi, oligonucleotides (oligos) have re-emerged as a major pharmaceutical target that may soon be required in ton quantities. However, it is questionable whether solid-phase oligo synthesis (SPOS) methods can provide a scalable synthesis. Liquid-phase oligo synthesis (LPOS) is intrinsically scalable and amenable to standard industrial batch synthesis techniques. However, most reported LPOS strategies rely upon at least one precipitation per chain extension cycle to separate the growing oligonucleotide from reaction debris. Precipitation can be difficult to develop and control on an industrial scale and, because many precipitations would be required to prepare a therapeutic oligonucleotide, we contend that this approach is not viable for large-scale industrial preparation. We are developing an LPOS synthetic strategy for 2′-methyl RNA phosphorothioate that is more amenable to standard batch production techniques, using organic solvent nanofiltration (OSN) as the critical scalable separation technology. We report the first LPOS-OSN preparation of a 2′-Me RNA phosphorothioate 9-mer, using commercial phosphoramidite monomers, and monitoring all reactions by HPLC, (31)P NMR spectroscopy and MS

    Stabilization of monodomain polarization in ultrathin PbTiO3 films

    Get PDF
    Using in situ high-resolution synchrotron x-ray scattering, the Curie temperature T-C has been determined for ultrathin c-axis epitaxial PbTiO3 films on conducting substrates (SrRuO3 on SrTiO3), with surfaces exposed to a controlled vapor environment. The suppression of T-C was relatively small, even for the thinnest film (1.2 nm). We observe that 180 degrees stripe domains do not form, indicating that the depolarizing field is compensated by free charge at both interfaces. This is confirmed by ab initio calculations that find polar ground states in the presence of ionic adsorbates.open15511

    A realistic assessment of methods for extracting gene/protein interactions from free text

    Get PDF
    Background: The automated extraction of gene and/or protein interactions from the literature is one of the most important targets of biomedical text mining research. In this paper we present a realistic evaluation of gene/protein interaction mining relevant to potential non-specialist users. Hence we have specifically avoided methods that are complex to install or require reimplementation, and we coupled our chosen extraction methods with a state-of-the-art biomedical named entity tagger. Results: Our results show: that performance across different evaluation corpora is extremely variable; that the use of tagged (as opposed to gold standard) gene and protein names has a significant impact on performance, with a drop in F-score of over 20 percentage points being commonplace; and that a simple keyword-based benchmark algorithm when coupled with a named entity tagger outperforms two of the tools most widely used to extract gene/protein interactions. Conclusion: In terms of availability, ease of use and performance, the potential non-specialist user community interested in automatically extracting gene and/or protein interactions from free text is poorly served by current tools and systems. The public release of extraction tools that are easy to install and use, and that achieve state-of-art levels of performance should be treated as a high priority by the biomedical text mining community

    Dynamical Axion Field in Topological Magnetic Insulators

    Full text link
    Axions are very light, very weakly interacting particles postulated more than 30 years ago in the context of the Standard Model of particle physics. Their existence could explain the missing dark matter of the universe. However, despite intensive searches, they have yet to be detected. In this work, we show that magnetic fluctuations of topological insulators couple to the electromagnetic fields exactly like the axions, and propose several experiments to detect this dynamical axion field. In particular, we show that the axion coupling enables a nonlinear modulation of the electromagnetic field, leading to attenuated total reflection. We propose a novel optical modulators device based on this principle.Comment: 5 pages, 3 figure
    corecore