902 research outputs found

    Existence of stationary fronts in a system of two coupled wave equations with spatial inhomogeneity

    Get PDF
    We investigate the existence of stationary fronts in a coupled system of two sine-Gordon equations with a smooth, "hat-like" spatial inhomogeneity. The spatial inhomogeneity corresponds to a spatially dependent scaling of the sine-Gordon potential term. The uncoupled inhomogeneous sine-Gordon equation has stable stationary front solutions that persist in the coupled system. Carrying out a numerical investigation it is found that these inhomogeneous sine-Gordon fronts loose stability, provided the coupling between the two inhomogeneous sine-Gordon equations is strong enough, with new stable fronts bifurcating. In order to analytically study the bifurcating fronts, we first approximate the smooth spatial inhomogeneity by a piecewise constant function. With this approximation, we prove analytically the existence of a pitchfork bifurcation. To complete the argument, we prove that transverse fronts for a piecewise constant inhomogeneity persist for the smooth "hat-like" spatial inhomogeneity by introducing a fast-slow structure and using geometric singular perturbation theory

    Integration through transients for Brownian particles under steady shear

    Full text link
    Starting from the microscopic Smoluchowski equation for interacting Brownian particles under stationary shearing, exact expressions for shear-dependent steady-state averages, correlation and structure functions, and susceptibilities are obtained, which take the form of generalized Green-Kubo relations. They require integration of transient dynamics. Equations of motion with memory effects for transient density fluctuation functions are derived from the same microscopic starting point. We argue that the derived formal expressions provide useful starting points for approximations in order to describe the stationary non-equilibrium state of steadily sheared dense colloidal dispersions.Comment: 17 pages, Submitted to J. Phys.: Condens. Matter; revised version with minor correction

    A review of implant provision for hypodontia patients within a Scottish referral centre

    Get PDF
    Background: Implant treatment to replace congenitally missing teeth often involves multidisciplinary input in a secondary care environment. High quality patient care requires an in-depth knowledge of treatment requirements. Aim: This service review aimed to determine treatment needs, efficiency of service and outcomes achieved in hypodontia patients. It also aimed to determine any specific difficulties encountered in service provision, and suggest methods to overcome these. Methods: Hypodontia patients in the Unit of Periodontics of the Scottish referral centre under consideration, who had implant placement and fixed restoration, or review completed over a 31 month period, were included. A standardised data collection form was developed and completed with reference to the patient's clinical record. Information was collected with regard to: the indication for implant treatment and its extent; the need for, complexity and duration of orthodontic treatment; the need for bone grafting and the techniques employed and indicators of implant success. Conclusion: Implant survival and success rates were high for those patients reviewed. Incidence of biological complications compared very favourably with the literature

    Synchronization of organ pipes: experimental observations and modeling

    Full text link
    We report measurements on the synchronization properties of organ pipes. First, we investigate influence of an external acoustical signal from a loudspeaker on the sound of an organ pipe. Second, the mutual influence of two pipes with different pitch is analyzed. In analogy to the externally driven, or mutually coupled self-sustained oscillators, one observes a frequency locking, which can be explained by synchronization theory. Further, we measure the dependence of the frequency of the signals emitted by two mutually detuned pipes with varying distance between the pipes. The spectrum shows a broad ``hump'' structure, not found for coupled oscillators. This indicates a complex coupling of the two organ pipes leading to nonlinear beat phenomena.Comment: 24 pages, 10 Figures, fully revised, 4 big figures separate in jpeg format. accepted for Journal of the Acoustical Society of Americ

    Patient-reported outcomes on empagliflozin treatment in glycogen storage disease type Ib:An international questionnaire study

    Get PDF
    In patients with glycogen storage disease type Ib (GSD Ib), quality of life is severely hampered by neutropenia and neutropenia-associated symptoms. SGLT2 inhibitors are a new treatment option and have shown improved medical outcomes in more than 120 patients so far. The aim of this international questionnaire study was to assess patient-reported outcomes of this new treatment in GSD Ib patients. Patients and caregivers of pediatric patients were invited to complete a web-based questionnaire. This was designed to evaluate treatment effects of the SGLT2 inhibitor empagliflozin on clinical symptoms and important aspects of daily life including physical performance, sleep, social and work life, traveling, socioeconomic aspects, and quality of life. The questionnaire was completed by 73 respondents from 17 different countries. The mean duration of treatment was 15 months, the cumulative treatment time was 94.8 years. More than 80% of patients reported an improved quality of life. The number of hospitalizations was reduced (66% of patients), as well as the number of days absent from school or work. Granulocyte colony-stimulating factor (G-CSF) treatment could be stopped in 49% of patients and reduced in another 42%. Clear improvement of neutropenia and all neutropenia-associated symptoms was reported by the majority of patients. Additionally, patients or caregivers reported positive effects on appetite (63%), level of activity (75%), overall well-being (96%), and sleep (63%). Empagliflozin positively impacts many aspects of daily life including work and social life and thereby significantly improves quality of life of patients and caregivers.</p

    Resultaten berekeningen bedrijfsmaatregelen Melkveehouderij en Akkerbouw

    Get PDF
    Het project “Boeren en Agrobiodiversiteit” heeft als doel: Duurzaam Ondernemen in de agrarische sector te stimuleren door middel van biodiversiteit. Centraal hierin staat het zoveel mogelijk gebruik maken van natuurlijke processen binnen de agrarische bedrijfsvoering. Uitvoering van het project vindt plaats in drie proeftuinen, gelegen in de gebieden De Peel, De Kempen en De Duinboeren. Het ontbreken van inzicht van de bedrijfseconomische effecten en milieueffecten van biodiversiteitmaatregelen is nog als een gemis ervaren bij de verdere kennisverspreiding en opschaling bij de toepassing op de bedrijven. In dit onderdeel van het project wordt een uitwerking gemaakt voor het vergroten van het inzicht in bedrijfseconomische en milieueffecten van biodiversiteitmaatregelen

    Effects of Antenatal Glucocorticoid Therapy on Hippocampal Histology of Preterm Infants

    Get PDF
    Objective: To investigate if antenatal glucocorticoid treatment has an effect on hippocampal histology of the human preterm newborn. Patients and Methods: Included were consecutive neonates with a gestational age between 24 and 32 weeks, who were born between 1991 to 2009, who had died within 4 days after delivery and underwent brain autopsy. Excluded were neonates with congenital malformations and neonates treated postnatally with glucocorticoids. The brains were routinely fixed, samples of the hippocampus were stained with haematoxylin and eosin and sections were examined for presence or absence of large and small neurons in regions of the hippocampus. Additional staining with GFAP, neurofilament and vimentin was performed to evaluate gliosis and myelination. The proliferation marker Ki67 was used to evaluate neuronal proliferation. Staining with acid fuchsin-thionin was performed to evaluate ischemic damage. Results: The hippocampi of ten neonates who had been treated with antenatal glucocorticoids showed a lower density of large neurons (p = 0.01) and neurons irrespective of size (p = 0.02) as compared to eleven neonates who had not been treated with glucocorticoids. No difference was found in density of small neurons, in myelination, gliosis, proliferation or ischemic damage. Conclusion: We found a significantly lower density of neurons in the hippocampus of neonates after antenata

    Maternal-to-fetal allopurinol transfer and xanthine oxidase suppression in the late gestation pregnant rat.

    Get PDF
    Fetal brain hypoxic injury remains a concern in high-risk delivery. There is significant clinical interest in agents that may diminish neuronal damage during birth asphyxia, such as in allopurinol, an inhibitor of the prooxidant enzyme xanthine oxidase. Here, we established in a rodent model the capacity of allopurinol to be taken up by the mother, cross the placenta, rise to therapeutic levels, and suppress xanthine oxidase activity in the fetus. On day 20 of pregnancy, Wistar dams were given 30 or 100 mg kg(-1) allopurinol orally. Maternal and fetal plasma allopurinol and oxypurinol concentrations were measured, and xanthine oxidase activity in the placenta and maternal and fetal tissues determined. There were significant strong positive correlations between maternal and fetal plasma allopurinol (r = 0.97, P < 0.05) and oxypurinol (r = 0.88, P < 0.05) levels. Under baseline conditions, maternal heart (2.18 ± 0.62 mU mg(-1)), maternal liver (0.29 ± 0.08 mU mg(-1)), placenta (1.36 ± 0.42 mU mg(-1)), fetal heart (1.64 ± 0.59 mU mg(-1)), and fetal liver (0.14 ± 0.08 mU mg(-1)) samples all showed significant xanthine oxidase activity. This activity was suppressed in all tissues 2 h after allopurinol administration and remained suppressed 24 h later (P < 0.05), despite allopurinol and oxypurinol levels returning toward baseline. The data establish a mammalian model of xanthine oxidase inhibition in the mother, placenta, and fetus, allowing investigation of the role of xanthine oxidase-derived reactive oxygen species in the maternal, placental, and fetal physiology during healthy and complicated pregnancy

    Improved inflammatory bowel disease, wound healing and normal oxidative burst under treatment with empagliflozin in glycogen storage disease type Ib

    Get PDF
    BACKGROUND: Glycogen storage disease type Ib (GSD Ib) is a rare inborn error of glycogen metabolism due to mutations in SLC37A4. Besides a severe form of fasting intolerance, the disorder is usually associated with neutropenia and neutrophil dysfunction causing serious infections, inflammatory bowel disease, oral, urogenital and perianal lesions as well as impaired wound healing. Recently, SGLT2 inhibitors such as empagliflozin that reduce the plasma levels of 1,5-anhydroglucitol have been described as a new treatment option for the neutropenia and neutrophil dysfunction in patients with GSD Ib. RESULTS: We report on a 35-year-old female patient with GSD Ib who had been treated with G-CSF for neutropenia since the age of 9. She had a large chronic abdominal wound as a consequence of recurrent operations due to complications of her inflammatory bowel disease. Treatment with 20 mg empagliflozin per day resulted in normalisation of the neutrophil count and neutrophil function even after termination of G-CSF. The chronic abdominal wound that had been unchanged for 2 years before the start of empagliflozin nearly closed within 12 weeks. No side effects of empagliflozin were observed. CONCLUSION: SGLT2 inhibitors are a new and probably safe treatment option for GSD Ib-associated neutropenia and neutrophil dysfunction. We hypothesize that restoration of neutrophil function and normalisation of neutrophil apoptosis leads to improvement of wound healing and ameliorates symptoms of inflammatory bowel disease

    Transverse instability and its long-term development for solitary waves of the (2+1)-Boussinesq equation

    Get PDF
    The stability properties of line solitary wave solutions of the (2+1)-dimensional Boussinesq equation with respect to transverse perturbations and their consequences are considered. A geometric condition arising from a multi-symplectic formulation of this equation gives an explicit relation between the parameters for transverse instability when the transverse wavenumber is small. The Evans function is then computed explicitly, giving the eigenvalues for transverse instability for all transverse wavenumbers. To determine the nonlinear and long time implications of transverse instability, numerical simulations are performed using pseudospectral discretization. The numerics confirm the analytic results, and in all cases studied, transverse instability leads to collapse.Comment: 16 pages, 8 figures; submitted to Phys. Rev.
    • …
    corecore