329 research outputs found

    Inference for an anisotropic diffusion model

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    AbstractThe vector sum of a white noise in an unknown hyperspace and an Ornstein-Uhlenbeck process in an unknown line is observed through sharp linear test functions over a finite time span. The parameters associated with the white noise (including the hyperplane) are determinable with precision and index the measure-equivalence classes in the relevant sample space. An intraclass relative density provides a basis for Bayesian inference of the remaining parameters

    Digital public infrastructure and public value: What is ‘public’ about DPI?

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    Digital Public Infrastructures (DPI) are becoming increasingly relevant in the policy and academic domains, with DPI not just being regulated, but funded and created by governments, international organisations, philanthropies and the private sector. However, these transformations are not neutral; they have a direction. This paper addresses how to ensure that DPI is not only regulated but created and governed for the common good by maximising public value creation. Our analysis makes explicit which normative values may be associated with DPI development. We also argue that normative values are necessary but not sufficient for maximising public value creation with DPI, and that a more proactive role of the state and governance are key. In this work, policymakers and researchers will find valuable frameworks for understanding where the value-creation elements of DPI come from and how to design a DPI governance that maximises public value

    The effect of composition and thickness on the mechanism and kinetics of filiform corrosion occurring on zinc-aluminium-magnesium coated steel

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    The effect of coating thickness and composition on the kinetics of acetic acid-induced filiform corrosion (FFC) on Zinc-Aluminium-Magnesium (ZAM) coated steel is investigated. Scribe defects are created in organic coatings applied to ∼10 μm coatings of varying composition (1−6 wt.%. Al, 1−3 wt. % Mg), and fixed composition (Zn-1.5 wt. % Al- 1.5 wt.% Mg) but varying thickness (5−27 μm). FCC decreases with increasing Al (at fixed wt. % Mg) and thickness. A linear trend exists between thickness and iron exposure time. Findings are consistent with FFC advancing via a penetrative coating mechanism whereby exposed iron couples to the coating

    Patients' and partners' health-related quality of life before and 4 months after coronary artery bypass grafting surgery

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    Background: Patients having coronary artery bypass grafting (CABG) often depend on their partners for assistance before and after surgery. Whilst patients' physical and mental health usually improves after surgery little is known about the partners' health-related quality of life (HRQoL) in CABG. If the partners' physical and emotional health is poor this can influence their caregiving role and ability to support the patient. This study aimed: to increase understanding of patients' and partners' HRQoL before and after CABG; to explore whether patients' and partners' pre-operative socio-demographics and HRQoL predict their own, and also partners' HRQoL 4 months after CABG. Methods: This prospective study recruited 84 dyads (patients 84% males, aged 64.5 years; partners 94% females, aged 61.05 years). Patients' and partners' perceived health status was assessed using the Short-Form 12 Health Survey. Patients' physical limitation, angina symptoms and treatment satisfaction were assessed using the Seattle Angina Questionnaire. Partners' emotional, physical and social functioning was assessed using the Quality of Life of Cardiac Spouses Questionnaire. Data were analysed using hierarchical multiple (logistic) regressions, repeated measures analysis of variance, paired t test and Chi square. Results: Patients most likely to have poorer physical health post-operatively were associated with partners who had poorer pre-operative physical health. Partners most likely to have poorer emotional, physical and social functioning post-operatively were associated with patients who had poorer pre-operative mental health. Patients" and partners' poorer post-operative HRQoL was also explained by their poorer pre-operative HRQoL. Conclusion: The partners' involvement should be considered as part of patients' pre-operative assessment. Special attention needs be paid to patients' pre-operative mental health since it is likely to impact on their post-operative mental health and the partner's emotional, physical and social functioning

    Vibrational dynamics in water from the molecule's perspective

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.Vita.Includes bibliographical references.Liquid water is a fascinating substance, ubiquitous in chemistry, physics, and biology. Its remarkable physical and chemical properties stem from the intricate network of hydrogen bonds that connect molecular participants. The structures and energetics of the network can explain the physical properties of the substance on macroscopic length scales, but the events that initiate many chemical reactions in water occur on the time scales of [similar to] 0.1 - 1 picosecond. The experimental challenges of measuring specific molecular motions on this time scale are formidable. The absorption frequency of the OH stretch of HOD in liquid Dâ‚‚0 is sensitive to the hydrogen bonding and molecular environment of the liquid. Ultrafast IR experiments endeavor to measure fluctuations in the hydrogen bond network by measuring spectral fluctuations on femtosecond time scales, but the data do not easily lend themselves to a direct microscopic interpretation. Computer simulations of empirical models, however, offer explicit microscopic detail but must be adapted to include a quantum mechanical vibration. I have developed methods in computer simulation to relate spectral fluctuations of the OH stretch in liquid Dâ‚‚0 to explicit microscopic information. The experiments also inform the simulation by providing important quantitative data about the fidelity and accuracy of a chosen molecular model, and help build a qualitative picture of hydrogen bonding in water. Our atomistic model reveals that ultrafast experiments of HOD in liquid Dâ‚‚0 measure transient fluctuations of the liquid's electric field. On the fastest time scales, localized fluctuations drive dephasing, while on longer time scales larger scale molecular reorganization destroys vibrational coherence.(cont.) Because electric fields drive vibrational dephasing, the frequency of the OH stretch is particularly sensitive to the microscopic details of the molecular potential. With collaborators, I have examined the accuracy of emerging fluctuating charge models for water and the role that molecular polarizability plays in the vibrational spectroscopy. In liquid water at ambient conditions, roughly 90 % of the hydrogen bonds are intact. I have examined the fates and the fundamental chemical nature of the remaining 10 % of the "broken" hydrogen bonds. We consider two reaction mechanisms that describe how hydrogen bonds change partners. In the first scenario, broken hydrogen bonds exist in stable chemical equilibrium with intact hydrogen bonds. In an alternate scenario, the broken hydrogen bond is not a meta-stable chemical state but instead a species that molecules visit during natural equilibrium fluctuations or when trading hydrogen bonding partners. I show how the methods of condensed phase reaction dynamics can be directly applied to vibrational spectroscopy of reactive systems and how experimental 2D IR spectra can distinguish between the two mechanistic scenarios. Our data support the notion that broken hydrogen bonds are an intrinsically unstable species in water and return to form hydrogen bonds on the time scale of intermolecular motions.by Joel David Eaves.Ph.D

    Race had no place in scholarship plan

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    Editorial columns by David R. Bowen, U.S. Representative from Mississippi (D)\u27 1973-1983.https://scholarsjunction.msstate.edu/db-columns/1006/thumbnail.jp

    Substrate utilization during submaximal exercise in children with a severely obese parent

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    Background We have reported a reduction in fatty acid oxidation (FAO) at the whole-body level and in skeletal muscle in severely obese (BMI ≥ 40 kg/m2) individuals; this defect is retained in cell culture suggesting an inherent component. The purpose of the current study was to determine if an impairment in whole-body fatty acid oxidation (FAO) was also evident in children with a severely obese parent. Methods Substrate utilization during submaximal exercise (cycle ergometer) was determined in children ages 8–12 y with a severely obese parent (OP, n = 13) or two lean/non-obese (BMI range of 18 to 28 kg/m2) parents (LP, n = 13). A subgroup of subjects (n = 3/group) performed 4 weeks of exercise training with substrate utilization measured after the intervention. Results The children did not differ in age (LP vs. OP, respectively) (10.7 ± 0.5 vs. 10.2 ± 0.5 y), BMI percentile (65.3 ± 5.2 vs. 75.9 ± 7), Tanner Stage (1.4 ± 0.2 vs. 1.5 ± 0.2), VO2peak (40.3 ± 2.7 vs. 35.6 ± 2.6 ml/kg/min) or physical activity levels (accelerometer). At the same absolute workload of 15 W (~38% VO2peak), RER was significantly (P ≤ 0.05) lower in LP vs. OP (0.83 ± 0.02 vs. 0.87 ± 0.01) which was reflected in a reduced reliance on FAO for energy production in the OP group (58.6 ± 5.1 vs. 43.1 ± 4.0% of energy needs during exercise from FAO). At a higher exercise intensity (~65% VO2peak) there were no differences in substrate utilization between LP and OP. After exercise training RER tended to decrease (P = 0.06) at the 15 W workload, suggesting an increased reliance on FAO regardless of group. Conclusions These findings suggest that the decrement in FAO with severe obesity has an inherent component that may be overcome with exercise training
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