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Search Results: 1 - 10 of 270733 matches for " David R Bishop "
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Length-scale competition in the damped sine-Gordon chain
David Cai,A. R. Bishop,Angel Sanchez
Physics , 1992,
Abstract: It is shown that there are two different regimes for the damped sine-Gordon chain driven by the spatio-temporal periodic force $\Gamma sin(\omega t - k_{n} x)$ with a flat initial condition. For $\Gamma_{c}(n)$ to a translating {\em 2-breather} excitation from a state locked to the driver. For $\omega < k_{n}$, the excitations of the system are the locked states with the phase velocity $\omega/k_{n}$ in all the region of $\Gamma$ studied. In the first regime, the frequency of the breathers is controlled by $\omega$, and the velocity of the breathers, controlled by $k_{n}$, is shown to be the group velocity determined from the linear dispersion relation for the sine-Gordon equation. A linear stability analysis reveals that, in addition to two competing length-scales, namely, the width of the breathers and the spatial period of the driving, there is one more length-scale which plays an important role in controlling the dynamics of the system at small driving. In the second regime the length-scale $k_{n}$ controls the excitation. The above picture is further corroborated by numerical nonlinear spectral analysis. An energy balance estimate is also presented and shown to predict the critical value of $\Gamma$ in good agreement with the numerics.
A prospective study of monitoring practices for metabolic disease in antipsychotic-treated community psychiatric patients
Paul Mackin, David R Bishop, Helen MO Watkinson
BMC Psychiatry , 2007, DOI: 10.1186/1471-244x-7-28
Abstract: We conducted a prospective cohort study of 106 community-treated psychiatric patients from across the diagnostic spectrum from the Northeast of England to investigate changes in metabolic status and monitoring practices for metabolic and cardiovascular disease. We undertook detailed anthropometric and metabolic assessment at baseline and follow-up, and examined clinical notes and hospital laboratory records to ascertain monitoring practices.A high prevalence of undiagnosed and untreated metabolic disease was present at baseline assessment. Mean follow-up time was 599.3 (SD ± 235.4) days. Body mass index (p < 0.005) and waist circumference (p < 0.05) had significantly increased at follow-up, as had the number of individuals who were either overweight or obese. Fifty-three per cent of individuals had hypertriglyceridemia, and 31% had hypercholesterolemia, but only 7% were receiving lipid-lowering therapy. Monitoring practices were poor. Recording of measures of adiposity occurred in 0% of individuals, and > 50% of subjects had neither blood glucose nor lipids monitored during the follow-up period.This cohort has a high prevalence of metabolic disease and heightened cardiovascular risk. Despite the publication of a number of recommendations regarding physical health screening in this population, monitoring rates are poor, and physical health worsened during the follow-up period.Severe mental illness (SMI) is associated with a significant excess of physical co-morbidity and mortality [1,2], and as such represents a major public health concern. Previous studies have reported a high prevalence of undiagnosed and untreated metabolic disorders and cardiovascular risk factors in patients with SMI [3-7]. Consensus statements from the US [8] and UK [9] have recommended stringent monitoring of metabolic status and cardiovascular risk factors in psychiatric patients receiving antipsychotic drugs, and recently published UK guidelines from the National Institute for Health and Cli
Localized States in Discrete Nonlinear Schr?dinger Equations
David Cai,A. R. Bishop,Niels Gr?nbech-Jensen
Physics , 1993, DOI: 10.1103/PhysRevLett.72.591
Abstract: A new 1-D discrete nonlinear Schr\"{o}dinger (NLS) Hamiltonian is introduced which includes the integrable Ablowitz-Ladik system as a limit. The symmetry properties of the system are studied. The relationship between intrinsic localized states and the soliton of the Ablowitz-Ladik NLS is discussed. It is pointed out that a staggered localized state can be viewed as a particle of a {\em negative} effective mass. It is shown that staggered localized states can exist in the discrete dark NLS. The motion of localized states and Peierls-Nabarro pinning are studied.
Quantification of HTLV-I proviral load in experimentally infected rabbits
Tong-Mao Zhao, Bishop Hague, David L Caudell, R Mark Simpson, Thomas J Kindt
Retrovirology , 2005, DOI: 10.1186/1742-4690-2-34
Abstract: A real-time PCR assay was used to measure proviral load in blood and tissue samples from a series of rabbits infected using HTLV-1 inocula prepared as either cell-free virus particles, infected cells or blood, or by naked DNA injection. Proviral loads from asymptomatically infected rabbits showed levels corresponding to those reported for human patients with clinically silent HTLV-1 infections. Proviral load was comparably increased in 50% of experimentally infected rabbits that developed either spontaneous benign or malignant tumors while infected. Similarly elevated provirus was found in organs of rabbits with experimentally induced acute leukemia/lymphoma-like disease. Levels of provirus in organs taken at necropsy varied widely suggesting that reservoirs of infections exist in non-lymphoid organs not traditionally thought to be targets for HTLV-1.Proviral load measurement is a valuable enhancement to the rabbit model for HTLV-1 infection providing a metric to monitor clinical status of the infected animals as well as a means for the testing of treatment to combat infection. In some cases proviral load in blood did not reflect organ proviral levels, revealing a limitation of this method for monitoring health status of HTLV-1 infected individuals.HTLV-I was the first human retrovirus discovered and was isolated from cell lines derived from patients with cutaneous T cell lymphoma or adult T cell leukemia (ATL) [1,2]. Later it was found that a variety of human diseases are causally associated with HTLV-I infection, including tropical spastic paraparesis (TSP) and myelopathy/tropical spastic paraparesis (HAM/TSP) [3,4].Previous studies of infected human subjects suggest that high proviral load is associated with increased tendency to develop HTLV-I-associated HAM/TSP, while ATL is associated with extremely high levels of provirus [5-8]. High proviral load was also found in HTLV-I infected patients with seborrheic dermatitis and severe anemia [9] and patients with rhe
A Role for PPARβ/δ in Ocular Angiogenesis
David Bishop-Bailey
PPAR Research , 2008, DOI: 10.1155/2008/825970
The Association between Vitamin D and Vascular Stiffness in Adolescents with and without Type 1 Diabetes
Rachel Lieberman, R. Paul Wadwa, Nhung Nguyen, Franziska K. Bishop, Christina Reinick, Janet K. Snell-Bergeon, David M. Maahs
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0077272
Abstract: Objective Vitamin D deficiency is common and associated with increased cardiovascular disease (CVD) risk. Pulse wave velocity (PWV) is a marker of vascular stiffness associated with CVD. We hypothesized that Vitamin D (25 (OH) D) levels would be inversely associated with PWV in youth with and without type 1 diabetes (T1D). Study Design Comparisons were made between adolescents with T1D (n = 211; age = 17.5±2.3 years; diabetes duration = 10.9±3.2 years; A1c = 9.1±1.7%) and non-DM controls (n = 67; age = 16.9±1.9 years). PWV was measured in the carotid-femoral segment (Sphygmocor Vx, AtCor Medical, Lisle, IL). Results Vitamin D levels were similar in adolescents with T1D and controls (27.7±0.7 v. 26.0±1.3 ng/ml; p = 0.26). Vitamin D was significantly inversely associated with PWV after adjusting for age, sex, quarter of the year, and race-ethnicity in adolescents with T1D (beta = ?0.01±0.004, p = 0.02) but not in the non-DM adolescents (beta = ?0.008±0.008, p = 0.32). Vitamin D remained significantly associated with PWV after additionally adjusting for hs-CRP in adolescents with T1D (?0.01±0.004, p = 0.01). After adjusting for BMI z-score, lipids, or blood pressure, the relationship of Vitamin D with PWV was not significant. Conclusions Vitamin D levels were inversely associated with PWV in adolescents with T1D, but not independently of BMI, lipids, or blood pressure. Our data contrast with other reports and suggest further research is indicated to determine if Vitamin D supplementation would be beneficial to lower CVD risk in adolescents with T1D with vitamin D insufficiency or deficiency.
Oral Health Knowledge and Behaviors among Adolescents with Type 1 Diabetes
Valerie A. Orlando,Lonnie R. Johnson,Anne R. Wilson,David M. Maahs,R. Paul Wadwa,Franziska K. Bishop,Fran Dong,Elaine H. Morrato
International Journal of Dentistry , 2010, DOI: 10.1155/2010/942124
Abstract: Early onset and more advanced periodontal disease has been reported for children with diabetes. We surveyed oral health knowledge, attitudes, and behaviors among adolescents with diabetes in order to inform potential intervention strategies. Study subjects were youth (ages 12–19 years) with type 1 diabetes (N = 90) participating in a cohort study investigating determinants of periodontal disease at a regional pediatric diabetes specialty clinic. Over 90% of the youth had been instructed on how to brush and floss and had preventive dental care in the past year. However, 44% knew that periodontal disease is associated with diabetes and 32% knew that it can start in childhood with bleeding gums. Despite being at high risk for developing periodontal disease, the mean toothbrushing frequency was once per day and 42% did not floss. Significant opportunity exists for improving periodontal disease knowledge and adoption of preventive oral hygiene behaviors in adolescents with diabetes. 1. Introduction The World Health Organization estimates that more than 180 million people worldwide have diabetes mellitus, a number expected to double in the next twenty years [1]. In the United States, the prevalence of diabetes in children under 20 years of age is 2.0 cases per 1,000 [2], accounting for approximately 154,369 children in 2001 [3]. With its rising incidence, diabetes has captured the attention of specialist and generalist practitioners in both medicine and dentistry. Periodontal diseases have been termed “the sixth complication of diabetes mellitus” [4]. Researchers suspect that the link between diabetes and periodontal disease may be bidirectional; the body’s response to periodontal pathogens may be exacerbated in individuals with diabetes and proinflammatory cytokines produced by gingival tissues during chronic periodontal infection may gain access to the bloodstream leading to increased insulin resistance and poor glycemic control [5, 6]. In a sample of adults with type 1 diabetes, periodontal disease severity was associated with both the duration of diabetes and the presence of diabetes complications [7]. The control of bacterial plaque through proper oral care is essential to overall systemic health and is becoming recognized as an important element in a comprehensive approach to treatment of the diabetic patient [8, 9]. Several reports have established the relationship between diabetes in children and periodontal disease [10–17]. Early investigations into the periodontal health of children with diabetes demonstrate expected correlations between poor
Field-Isolated Genotypes of Mycobacterium bovis Vary in Virulence and Influence Case Pathology but Do Not Affect Outbreak Size
David M. Wright, Adrian R. Allen, Thomas R. Mallon, Stanley W. J. McDowell, Stephen C. Bishop, Elizabeth J. Glass, Mairead L. Bermingham, John A. Woolliams, Robin A. Skuce
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074503
Abstract: Strains of many infectious agents differ in fundamental epidemiological parameters including transmissibility, virulence and pathology. We investigated whether genotypes of Mycobacterium bovis (the causative agent of bovine tuberculosis, bTB) differ significantly in transmissibility and virulence, combining data from a nine-year survey of the genetic structure of the M. bovis population in Northern Ireland with detailed records of the cattle population during the same period. We used the size of herd breakdowns as a proxy measure of transmissibility and the proportion of skin test positive animals (reactors) that were visibly lesioned as a measure of virulence. Average breakdown size increased with herd size and varied depending on the manner of detection (routine herd testing or tracing of infectious contacts) but we found no significant variation among M. bovis genotypes in breakdown size once these factors had been accounted for. However breakdowns due to some genotypes had a greater proportion of lesioned reactors than others, indicating that there may be variation in virulence among genotypes. These findings indicate that the current bTB control programme may be detecting infected herds sufficiently quickly so that differences in virulence are not manifested in terms of outbreak sizes. We also investigated whether pathology of infected cattle varied according to M. bovis genotype, analysing the distribution of lesions recorded at post mortem inspection. We concentrated on the proportion of cases lesioned in the lower respiratory tract, which can indicate the relative importance of the respiratory and alimentary routes of infection. The distribution of lesions varied among genotypes and with cattle age and there were also subtle differences among breeds. Age and breed differences may be related to differences in susceptibility and husbandry, but reasons for variation in lesion distribution among genotypes require further investigation.
Metodi economici per la risoluzione di conflitti nell'uso delle risorse idriche
R.C. Bishop
Aestimum , 1990,
Oldest Evidence of Toolmaking Hominins in a Grassland-Dominated Ecosystem
Thomas W. Plummer,Peter W. Ditchfield,Laura C. Bishop,John D. Kingston,Joseph V. Ferraro,David R. Braun,Fritz Hertel,Richard Potts
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0007199
Abstract: Major biological and cultural innovations in late Pliocene hominin evolution are frequently linked to the spread or fluctuating presence of C4 grass in African ecosystems. Whereas the deep sea record of global climatic change provides indirect evidence for an increase in C4 vegetation with a shift towards a cooler, drier and more variable global climatic regime beginning approximately 3 million years ago (Ma), evidence for grassland-dominated ecosystems in continental Africa and hominin activities within such ecosystems have been lacking.
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