1,009 research outputs found

    Supersymmetric Toda Field Theories

    Full text link
    We present new supersymmetric extensions of Conformal Toda and AN(1)A^{(1)}_N Affine Toda field theories. These new theories are constructed using methods similar to those that have been developed to find supersymmetric extensions of two-dimensional bosonic sigma models with a scalar potential. In particular, we show that the Conformal Toda field theory admits a (1,1)-supersymmetric extension, and the AN(1)A^{(1)}_N Affine Toda field admits a (1,0)-supersymmetric extension.Comment: 13 page

    Quantum Kinks: Solitons at Strong Coupling

    Full text link
    We examine solitons in theories with heavy fermions. These ``quantum'' solitons differ dramatically from semi-classical (perturbative) solitons because fermion loop effects are important when the Yukawa coupling is strong. We focus on kinks in a (1+1)(1+1)--dimensional ϕ4\phi^4 theory coupled to fermions; a large-NN expansion is employed to treat the Yukawa coupling gg nonperturbatively. A local expression for the fermion vacuum energy is derived using the WKB approximation for the Dirac eigenvalues. We find that fermion loop corrections increase the energy of the kink and (for large gg) decrease its size. For large gg, the energy of the quantum kink is proportional to gg, and its size scales as 1/g1/g, unlike the classical kink; we argue that these features are generic to quantum solitons in theories with strong Yukawa couplings. We also discuss the possible instability of fermions to solitons.Comment: 21 pp. + 2 figs., phyzzx, JHU-TIPAC-92001

    Homogeneous Bubble Nucleation driven by local hot spots: a Molecular Dynamics Study

    Full text link
    We report a Molecular Dynamics study of homogenous bubble nucleation in a Lennard-Jones fluid. The rate of bubble nucleation is estimated using forward-flux sampling (FFS). We find that cavitation starts with compact bubbles rather than with ramified structures as had been suggested by Shen and Debenedetti (J. Chem. Phys. 111:3581, 1999). Our estimate of the bubble-nucleation rate is higher than predicted on the basis of Classical Nucleation Theory (CNT). Our simulations show that local temperature fluctuations correlate strongly with subsequent bubble formation - this mechanism is not taken into account in CNT

    Legislating Phonics: Settled Science or Political Polemics?

    Get PDF
    In this commentary, we identify a phonics-first ideology and its polemical distortions of research and science to promote legislation that constrains and diminishes the teaching of reading. We affirm our own, and a majority of reading professionals’, commitment to teaching phonics. However, we argue that phonics instruction is more effective when embedded in a more comprehensive program of literacy instruction that accommodates students’ individual needs and multiple approaches to teaching phonics—a view supported by substantial research. After summarizing the politicization of phonics in the United States, we critique a legislated training course for teachers in Tennessee as representative of how a phonics-first ideology is expressed polemically for political purposes. We contrast it with a more collaboratively developed, balanced, nonlegislative approach in the previous governor’s administration. Specifically, the training course (a) makes an unfounded claim that there is a national reading crisis that can be traced to insufficient or inappropriate phonics instruction; (b) distorts, misrepresents, or omits relevant research findings and recommendations, most prominently from the report of the National Reading Panel; (c) inaccurately suggests that “balanced literacy instruction” is “whole language” instruction in disguise; and (d) wrongly claims that its views of phonics are based on a settled science of reading

    Recent Progress in the Use of Glucagon and Glucagon Receptor Antagonists in the Treatment of Diabetes Mellitus

    Get PDF
    Glucagon is an important pancreatic hormone, released into blood circulation by alpha cells of the islet of Langerhans. Glucagon induces gluconeogenesis and glycogenolysis in hepatocytes, leading to an increase in hepatic glucose production and subsequently hyperglycemia in susceptible individuals. Hyperglucagonemia is a constant feature in patients with T2DM. A number of bioactive agents that can block glucagon receptor have been identified. These glucagon receptor antagonists can reduce the hyperglycemia associated with exogenous glucagon administration in normal as well as diabetic subjects. Glucagon receptor antagonists include isoserine and beta-alanine derivatives, bicyclic 19-residue peptide BI-32169, Des-His1-[Glu9] glucagon amide and related compounds, 5-hydroxyalkyl-4-phenylpyridines, N-[3-cano-6- (1,1 dimethylpropyl)-4,5,6,7-tetrahydro-1-benzothien-2-yl]-2-ethylbutamide, Skyrin and NNC 250926. The absorption, dosage, catabolism, excretion and medicinal chemistry of these agents are the subject of this review. It emphasizes the role of glucagon in glucose homeostasis and how it could be applied as a novel tool for the management of diabetes mellitus by blocking its receptors with either monoclonal antibodies, peptide and non-peptide antagonists or gene knockout techniques

    Idiopathic radiographic apical root resorption in wind instrument players

    Get PDF
    Root resorption of the permanent teeth involves an elaborate interaction among inflammatory cells resulting in loss of dental hard tissues. This report describes three clinical cases where idiopathic root resorption occurred in wind instrument playing patients. These patients produce adequate non-orthodontic forces, while playing their instruments, to expose their teeth to root resorbing force. Careful clinical monitoring of patients' teeth should be undertaken, as the additive effects of orthodontic treatment and musical habits are unknown

    Management preferences following radical inguinal orchidectomy for Stage I testicular seminoma in Australasia

    Full text link
    A survey to evaluate the preferred patterns of management of Stage I seminoma was conducted during March 2001. The questionnaire was distributed by the Royal Australian and New Zealand College of Radiologists to all qualified radiation oncologists, 74 out of 170 responded. All performed a staging CT scan of the abdomen and pelvis. Thoracic imaging consisted of either chest X-ray (29%) or chest CT (38%) while 33% performed both. Fifty-four percent of radiation oncologists discussed surveillance with their patients but estimated that 5% or less would choose this option. The most commonly prescribed dose was 25 Gy in 15 or 20 fractions (79%). Sixty-five percent of respondents treated the para-aortic (PA) nodes alone. Forty-two of 48 clinicians treating the PA field reported a change in practice after publication of the Medical Research Council study in 1999. Of these, 40 and 23% perform CT scans of the pelvis annually and every 6 months. Thirty-one percent did no follow-up CT scan. Compared to a similar survey from North America, we are more likely to use PA fields and less likely to discuss surveillance. As in the USA, and in contrast to Canada, few patients choose surveillance. There is no consensus regarding the frequency of follow-up scans in either North America or Australasia.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75636/1/j.1440-1673.2002.01060.x.pd

    Structural, thermal and dissolution properties of MgO- and CaO-containing borophosphate glasses: effect of Fe2O3 addition

    Get PDF
    This paper investigated manufacture of high-durability phosphate glass fibres for biomedical applications. Five different borophosphate glass formulations in the systems of 45P2O5–5B2O3–5Na2O–(29 − x)CaO–16MgO–(x)Fe2O3 and 45P2O5–5B2O3–5Na2O–24CaO–(21 − x)MgO–(x)Fe2O3 where x = 5, 8 and 11 mol% were produced via melt quenching. The compositions and amorphous nature of the glasses were confirmed by ICP-MS and XRD, respectively. FTIR results indicated depolymerisation of the phosphate chains with a decrease in Q2 units with increasing Fe2O3 content. DSC analyses showed an increase in Tg by ~5 °C with an increment of 3 mol% in Fe2O3 content. The thermal properties were also used to calculate processing window (i.e. Tc,ons—Tg) and another parameter, Kgl, to determine the suitability for fibre drawing directly from melt, which equals (Tc,ons—Tg)/(Tl—Tc,ons). The degradation study conducted in PBS solution at 37 °C showed a decrease of 25–47% in degradation rate with increasing Fe2O3 content. This confirmed that the chemical durability of the glasses had increased, which was suggested to be due to Fe2O3 addition. Furthermore, the density measured via Archimedes method revealed a linear increase with increasing Fe2O3 content
    corecore