3,005 research outputs found

    Magnetic Monopole Noise

    Full text link
    Magnetic monopoles are hypothetical elementary particles exhibiting quantized magnetic charge m0=±(h/μ0e)m_0=\pm(h/\mu_0e) and quantized magnetic flux Φ0=±h/e\Phi_0=\pm h/e. A classic proposal for detecting such magnetic charges is to measure the quantized jump in magnetic flux Φ\Phi threading the loop of a superconducting quantum interference device (SQUID) when a monopole passes through it. Naturally, with the theoretical discovery that a plasma of emergent magnetic charges should exist in several lanthanide-pyrochlore magnetic insulators, including Dy2_2Ti2_2O7_7, this SQUID technique was proposed for their direct detection. Experimentally, this has proven extremely challenging because of the high number density, and the generation-recombination (GR) fluctuations, of the monopole plasma. Recently, however, theoretical advances have allowed the spectral density of magnetic-flux noise SΦ(ω,T)S_{\Phi}(\omega,T) due to GR fluctuations of ±m\pm m_* magnetic charge pairs to be determined. These theories present a sequence of strikingly clear predictions for the magnetic-flux noise signature of emergent magnetic monopoles. Here we report development of a high-sensitivity, SQUID based flux-noise spectrometer, and consequent measurements of the frequency and temperature dependence of SΦ(ω,T)S_{\Phi}(\omega,T) for Dy2_2Ti2_2O7_7 samples. Virtually all the elements of SΦ(ω,T)S_{\Phi}(\omega,T) predicted for a magnetic monopole plasma, including the existence of intense magnetization noise and its characteristic frequency and temperature dependence, are detected directly. Moreover, comparisons of simulated and measured correlation functions CΦ(t)C_{\Phi}(t) of the magnetic-flux noise Φ(t)\Phi(t) imply that the motion of magnetic charges is strongly correlated because traversal of the same trajectory by two magnetic charges of same sign is forbidden

    Visits to rheumatologists for arthritis: The role of access to primary care physicians, geographic availability of rheumatologists, and socioeconomic status

    Get PDF
    Objective. This multilevel study examines access to rheumatologists for all arthritis and inflammatory arthritis, taking into account geographic availability of rheumatologists, access to primary care physicians (PCPs), and population characteristics (e.g., socioeconomic status [SES]). Methods. We analyzed data from the population (age ≤18 years) living in the 105 health planning areas in Ontario, Canada on visits to physicians for arthritis and musculoskeletal disorders. Using data from a survey of rheumatologists and Geographic Information System analysis, an index of geographic availability for rheumatologists was calculated, incorporating distance between the population and rheumatologist locations and the number of hours per week of rheumatologist care. Multilevel Poisson regression was used to examine factors associated with the rates of rheumatology visits for inflammatory arthritis and all arthritis. Results. Controlling for age and sex, the rheumatologist availability index was associated with visit rates for all arthritis, but not inflammatory arthritis. Patients living in areas with low access to PCPs or low SES were less likely to have office visits to rheumatologists for all arthritis and inflammatory arthritis. Conclusion. Besides potential deficiencies in rheumatology provision, there may be access barriers to rheumatology services, particularly for populations with low access to PCPs or low SES. This is of special concern for patients with inflammatory arthritis for whom rheumatologist care is necessary. In developing models of care for arthritis, this study points to the need to pay attention to areas with low PCP resources and areas of low SES, as well as the location and amount of rheumatology services available

    Nurses\u27 Alumnae Association Bulletin, April 1962

    Get PDF
    Staff Nurses Association Alumnae Meetings 1961 Social Committee Clara Melville Scholarship Fund Ways and Means Report Cook Book Report Bulletin Committee Private Duty Nurse\u27s Section Hospital Report and Nursing Service Federal Nursing Service Practice of Nursing Report of Student Council Activities Medical Work in Ghan

    Power of grammatical evolution neural networks to detect gene-gene interactions in the presence of error

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>With the advent of increasingly efficient means to obtain genetic information, a great insurgence of data has resulted, leading to the need for methods for analyzing this data beyond that of traditional parametric statistical approaches. Recently we introduced Grammatical Evolution Neural Network (GENN), a machine-learning approach to detect gene-gene or gene-environment interactions, also known as epistasis, in high dimensional genetic epidemiological data. GENN has been shown to be highly successful in a range of simulated data, but the impact of error common to real data is unknown. In the current study, we examine the power of GENN to detect interesting interactions in the presence of noise due to genotyping error, missing data, phenocopy, and genetic heterogeneity. Additionally, we compare the performance of GENN to that of another computational method – Multifactor Dimensionality Reduction (MDR).</p> <p>Findings</p> <p>GENN is extremely robust to missing data and genotyping error. Phenocopy in a dataset reduces the power of both GENN and MDR. GENN is reasonably robust to genetic heterogeneity and find that in some cases GENN has substantially higher power than MDR to detect functional loci in the presence of genetic heterogeneity.</p> <p>Conclusion</p> <p>GENN is a promising method to detect gene-gene interaction, even in the presence of common types of error found in real data.</p

    Multi-Atom Quasiparticle Scattering Interference for Superconductor Energy-Gap Symmetry Determination

    Get PDF
    Complete theoretical understanding of the most complex superconductors requires a detailed knowledge of the symmetry of the superconducting energy-gap Δkα\Delta_\mathbf{k}^\alpha, for all momenta k\mathbf{k} on the Fermi surface of every band α\alpha. While there are a variety of techniques for determining Δkα|\Delta_\mathbf{k}^\alpha|, no general method existed to measure the signed values of Δkα\Delta_\mathbf{k}^\alpha. Recently, however, a new technique based on phase-resolved visualization of superconducting quasiparticle interference (QPI) patterns centered on a single non-magnetic impurity atom, was introduced. In principle, energy-resolved and phase-resolved Fourier analysis of these images identifies wavevectors connecting all k-space regions where Δkα\Delta_\mathbf{k}^\alpha has the same or opposite sign. But use of a single isolated impurity atom, from whose precise location the spatial phase of the scattering interference pattern must be measured is technically difficult. Here we introduce a generalization of this approach for use with multiple impurity atoms, and demonstrate its validity by comparing the Δkα\Delta_\mathbf{k}^\alpha it generates to the Δkα\Delta_\mathbf{k}^\alpha determined from single-atom scattering in FeSe where s±s_{\pm} energy-gap symmetry is established. Finally, to exemplify utility, we use the multi-atom technique on LiFeAs and find scattering interference between the hole-like and electron-like pockets as predicted for Δkα\Delta_\mathbf{k}^\alpha of opposite sign

    emb-1 Encodes the APC16 Subunit of the Caenorhabditis elegans Anaphase-Promoting Complex

    Get PDF
    In the nematode Caenorhabditis elegans, temperature-sensitive mutants of emb-1 arrest as one-cell embryos in metaphase of meiosis I in a manner that is indistinguishable from embryos that have been depleted of known subunits of the anaphase-promoting complex or cyclosome (APC/C). Here we show that the emb-1 phenotype is enhanced in double mutant combinations with known APC/C subunits and suppressed in double mutant combinations with known APC/C suppressors. In addition to its meiotic function, emb-1 is required for mitotic proliferation of the germline. These studies reveal that emb-1 encodes K10D2.4, a homolog of the small, recently discovered APC/C subunit, APC16

    Two-step synthesis of Fe2O3 and Co3O4 nanoparticles: towards a general method for synthesizing nanocrystalline metal oxides with high surface area and thermal stability

    Get PDF
    Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.A simple, two-step method using activated carbon (AC) as a support/scaffold was developed to synthesize metal oxide nanocrystalline materials (NCMs). In the first step, metal nitrate precursors were deposited by wet impregnation onto the AC, then heated in argon at 350 °C to immobilize the metal oxides. In the second step, the AC was removed by calcination in air at 500 °C, to obtain the unsupported metal oxide NCMs. Characterization by N2-sorption isotherms, TGA, XPS and EXAFS reveals that the metal oxide particles are crystalline and nanometre-sized, with surface areas up to 148 m2 g−1. Moreover, the TEM images show particle sizes in the range 5–10 nm, even after calcination at 500 °C for 2 h. Their thermal stability and high surface areas, together with the nanometre-sized structures, make them promising materials for catalytic applications (e.g., CO oxidation).DFG, EXC 314, Unifying Concepts in Catalysi

    Xtn3 is a developmentally expressed cardiac and skeletal muscle-specific novex-3 titin isoform

    Get PDF
    Titin proteins play an essential role in maintaining muscle function and structure. Recent work has implicated the involvement of the novex-3 titin isoform in sarcomere restructuring and disease. Unlike avian and mammalian systems, Xenopus laevis myogenesis is characterized by a wave of primary myogenesis followed by apoptosis of the primary muscles and formation of new muscles by secondary myogenesis. We show here that the Xenopus laevis novex-3 titin isoform (Xtn3) is developmentally expressed throughout the somites, heart, and primary muscles of the developing embryo. Downregulation of Xtn3 expression at tadpole stages appears to coincide with the change in myofiber composition from solely embryonic “fast” fiber types to myofibers containing both “fast” and “slow” fiber types. We demonstrate that Xtn3 is expressed early in the presomitic mesoderm and remains expressed in the somites, ventral myoblasts, and developing jaw muscles through late tailbud stage. Furthermore, we show that Xtn3 is expressed in the cardiac primordia prior to linear heart tube formation and remains expressed in the heart until tadpole stage, at which point it is downregulated in the heart except in discrete patches of cardiac cells. Finally, we demonstrate that Xtn3 transcripts are detectable in adult heart and muscle tissues

    Education and Learning Opportunities (NVP 2014, Report 3)

    Get PDF
    With support and collaboration from the W.K. Kellogg Foundation through the America Healing initiative,  researchers at the University of Michigan are leading the National Voices Project (NVP) from 2011-2016. The central goals of the NVP are to examine the sourcesof racial/ethnic inequity and other disparitiesfor children in the United States today and identify interventions that address disparities effectively.The NVP offers an unprecedented perspective on community-level opportunities for children throughout the country, in the domains of health and nutrition, education and learning, and economic security – through the eyes of adults whose occupations and volunteer work affect such opportunities. In other words, the NVP reflects the perceptions of individuals throughout the United States who are in a position to improve children's opportunities inthe future. We generally use the word "children" throughout the report to describe children from age 0-18 years, unless otherwise noted.Previous reports for NVP 2014 focused chiefly on respondent characteristics and findings regarding health,  healthcare, and nutrition. This report for NVP 2014 will center on findings related to children's education and learning
    corecore