5,309 research outputs found

    Properties and use of CMB power spectrum likelihoods

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    Fast robust methods for calculating likelihoods from CMB observations on small scales generally rely on approximations based on a set of power spectrum estimators and their covariances. We investigate the optimality of these approximation, how accurate the covariance needs to be, and how to estimate the covariance from simulations. For a simple case with azimuthal symmetry we compare optimality of hybrid pseudo-C_l CMB power spectrum estimators with the exact result, indicating that the loss of information is not negligible, but neither is it enough to have a large effect on standard parameter constraints. We then discuss the number of samples required to estimate the covariance from simulations, with and without a good analytic approximation, and assess the use of shrinkage estimators. Finally we discuss how to combine an approximate high-ell likelihood with a more exact low-ell harmonic-space likelihood as a practical method for accurate likelihood calculation on all scales.Comment: 15 pages, 11 figures; updated to match version accepted by PR

    Waste Identification and Elimination in HEIs: The Role of Lean Thinking

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    Purpose – The purpose of this paper is to translate the eight wastes of Lean for Higher Education Institutions (HEIs), identify some examples of each waste and to propose appropriate Lean solutions to those wastes. Design/methodology/approach – To identify wastes within HEIs a combination of observation and cause-and-effect analysis utilising brainstorming were employed using a convenience sample of HE academic staff. Findings – Once all eight wastes were successfully translated for HEIs a range of examples were identified in both academic and support services, including excessive movement of people, over production of materials, excessive inventory and waste of human resources. Appropriate Lean solutions to the identified wastes include the use of 5S, point-of-use-storage, process mapping/value stream mapping and level scheduling. Research limitations/implications – The cited examples come from a limited number of observations in only a few HEIs. More valid and reliable data would come from a more extensive sample of HEIs. Practical implications – In order to improve bottom-line performance in times of constrained resources HEIs can reduce waste and hence costs of poor quality by using Lean thinking and accessing, what Joseph Juran (1962) called, “The gold in the mine”. This can be done without reducing the level of services. Social implications – Particularly in a recession, HEIs need to show that they are using government funding (public money) in the most efficient and effective way possible. Lean thinking can help achieve both these objectives. Originality/value – Previous papers on Lean thinking applied to HEIs have concentrated on individual processes such as curriculum design or student assessment. This paper takes a holistic view demonstrating how Lean thinking theories can be practically applied across both academic and administrative areas of HEI operations

    Post-operative atrial fibrillation is influenced by beta-blocker therapy but not by pre-operative atrial cellular electrophysiology

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    We investigated whether post-cardiac surgery (CS) new-onset atrial fibrillation (AF) is predicted by pre-CS atrial cellular electrophysiology, and whether the antiarrhythmic effect of beta-blocker therapy may involve pre-CS pharmacological remodeling. Atrial myocytes were obtained from consenting patients in sinus rhythm, just prior to CS. Action potentials and ion currents were recorded using whole-cell patch-clamp technique. Post-CS AF occurred in 53 of 212 patients (25%). Those with post-CS AF were older than those without (67 ± 2 vs 62 ± 1 years, P = 0.005). In cells from patients with post-CS AF, the action potential duration at 50% and 90% repolarization, maximum upstroke velocity, and effective refractory period (ERP) were 13 ± 4 ms, 217 ± 16 ms, 185 ± 10 V/s, and 216 ± 14 ms, respectively (n = 30 cells, 11 patients). Peak L-type Ca2+ current, transient outward and inward rectifier K+ currents, and the sustained outward current were −5.0 ± 0.5, 12.9 ± 2.4, −4.1 ± 0.4, and 9.7 ± 1.0 pA/pF, respectively (13-62 cells, 7-19 patients). None of these values were significantly different in cells from patients without post-CS AF (P > 0.05 for each, 60-279 cells, 29-86 patients), confirmed by multiple and logistic regression. In patients treated >7 days with a beta-blocker pre-CS, the incidence of post-CS AF was lower than in non-beta-blocked patients (13% vs 27%, P = 0.038). Pre-CS beta-blockade was associated with a prolonged pre-CS atrial cellular ERP (P = 0.001), by a similar degree (∼20%) in those with and without post-CS AF. Conclusion: Pre-CS human atrial cellular electrophysiology does not predict post-CS AF. Chronic beta-blocker therapy is associated with a reduced incidence of post-CS AF, unrelated to a pre-CS ERP-prolonging effect of this treatment

    BIOGENIC SYNTHESIS OF SILVER NANOPARTICLES USING MANILKARA HEXANDRA (ROXB.) DUBARD STEM BARK EXTRACT AND IT’S PHYSICAL, CHEMICAL CHARACTERIZATION AND PHARMACEUTICAL EVALUATION

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    Objective: The present study was to synthesize nanoparticles using Manilkara hexandra stem bark extract its characterization and evaluating it by an antimicrobial and antioxidant assay. Methods: Manilkara hexandra stem bark silver nanoparticles (MHSB-AgNPs) was done by mixing silver nitrate (1 mmol) and aqueous stem bark extract and it was analyzed by UV-Visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), Zeta potential, Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDAX), Thermogravimetry/Differential Thermal Analysis (TG/DTA) and Differential scanning calorimetry (DSC). The antibacterial assay was done by a well diffusion method and also examined for antifungal assay was done by disk diffusion method and antioxidant potential Diphenyl-1-picryl hydrazyl (DPPH method) Results: Manilkara hexandra stem bark silver nanoparticles (MHSB-AgNPs) is characterized by various techniques such as UV-visible absorption spectrum ranges from 430 nm to 440 nm indicate silver nanoparticles. The Fourier Transform Infrared Spectroscopy consists of biomolecules acts as capping agent to form silver nanoparticles. Field Emission Scanning Electron Microscopy shows particle size ranges from 15 nm to 50 nm. Energy Dispersive Spectroscopy shows the presence of Silver. X-ray Diffraction corresponds to face-centered lattice planes (111), (200), (220) and (311). Dynamic Light Scattering show the range of 68 nm and Zeta potential show the negative value of-17 nm which has high stability. Silver nanoparticles is also examined by Thermogravimetry/Differential Thermal Analysis (TG/DTA) and Differential scanning calorimetry (DSC) this project the thermal stability of the nanoparticles. The aqueous stem bark is also examined by UV-visible absorption spectrum, Fourier Transform Infrared Spectroscopy (FTIR), and Gas Chromatography-Mass Spectrometry (GCMS). In GCMS 20 compounds were identified. Silver nanoparticles show high zone of inhibition in antimicrobial assays and act as a good antioxidant agent. Conclusion: It is eco-friendly, non-toxic, and it’s easy to synthesis and it shows good result in an antimicrobial and antioxidant assay can be applied in a pharmaceutical application

    PHYSICAL AND CHEMICAL CHARACTERIZATION OF GREEN SYNTHESIZED SILVER NANOPARTICLES USING STEM OF HIBISCUS VITIFOLIUS L. AND ITS ANTIMICROBIAL AND ANTIOXIDANT POTENTIAL

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    Objectives: The aim of our work was to synthesize the silver nanoparticle (AgNP) using Hibiscus vitifolius L. stem extract its characterization and evaluation of antimicrobial and antioxidant assay. Materials and Methods: The silver nitrate (1 mM) mixed with aqueous stem extract of H. vitifolius L. after the nanoparticles is examined by Fourier-transform infrared (FT-IR), ultraviolet-visible (UV-vis) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDAX), X-ray powder diffraction (XRD), dynamic light scattering (DLS), zeta potential, thermogravimetry/differential thermal analysis (TG/DTA), and differential scanning calorimetry (DSC). The aqueous stem extract is examined for phytochemical screening, gas chromatography–mass spectrometry (GC–MS) analysis, FT-IR, and UV-vis spectroscopy. The antibacterial, antifungal, and antioxidant assay were also evaluated for the AgNPs. Results: The aqueous stem extract shows 20 compounds in GC–MS analysis. The FT-IR and UV-vis spectroscopy show the biocompounds. H. vitifolius stem extract-AgNPs (HVS-AgNPs) examined in UV and FT-IR shows the presence of AgNPs, FE-SEM shows that the particle size is 30–70 nm, EDAX shows the presence of silver metal, and XRD shows that the particles are face-centered cubic. DLS shows the hydrodynamic size 136.9 nm, zeta potential shows the stability (−18.6 mV), and TG/DTA and DSC show that the particles are stable up to 335°C. The HVS-AgNPs are also evaluated in antimicrobial and antioxidant potential and the report shows a good inhibition. Conclusion: The stem extract of H. vitifolius L. can be used for green synthesis of AgNPs and could be used as antimicrobial and antioxidant potential

    Supply chain risk assessment approach for process quality risks

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    Purpose- The purpose of the paper is to proactively analyse and mitigate root causes of the process quality risks. The case study approach examines the effectiveness of the fuzzy logic approach for assessing the product and process related failure modes within global supply chain context. Design/Methodology/approach- The case study of a printed circuit board company in China is used as a platform for conducting the research. Using data triangulation, the data is collected and analysed through interviews, questionnaires, expert opinions and quantitative modelling for drawing useful insights. Findings- The fuzzy logic approach to FMEA provides a structured approach for understanding complex behaviour of failure modes and their associated risks for products and processes. Supply Chain Managers should conduct robust risk assessment during the design stage to avoid product safety and security risks. Research Limitations/implications- The research is based on a single case study. Multiple cases from different industry sectors may support in generalising the findings. Originality/Value- The study attempts to mitigate the root causes of product and processes using fuzzy approach to FMEA in supply chain network

    A new algorithm to diagnose atrial ectopic origin from multi lead ECG systems - insights from 3D virtual human atria and torso

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    Rapid atrial arrhythmias such as atrial fibrillation (AF) predispose to ventricular arrhythmias, sudden cardiac death and stroke. Identifying the origin of atrial ectopic activity from the electrocardiogram (ECG) can help to diagnose the early onset of AF in a cost-effective manner. The complex and rapid atrial electrical activity during AF makes it difficult to obtain detailed information on atrial activation using the standard 12-lead ECG alone. Compared to conventional 12-lead ECG, more detailed ECG lead configurations may provide further information about spatio-temporal dynamics of the body surface potential (BSP) during atrial excitation. We apply a recently developed 3D human atrial model to simulate electrical activity during normal sinus rhythm and ectopic pacing. The atrial model is placed into a newly developed torso model which considers the presence of the lungs, liver and spinal cord. A boundary element method is used to compute the BSP resulting from atrial excitation. Elements of the torso mesh corresponding to the locations of the placement of the electrodes in the standard 12-lead and a more detailed 64-lead ECG configuration were selected. The ectopic focal activity was simulated at various origins across all the different regions of the atria. Simulated BSP maps during normal atrial excitation (i.e. sinoatrial node excitation) were compared to those observed experimentally (obtained from the 64-lead ECG system), showing a strong agreement between the evolution in time of the simulated and experimental data in the P-wave morphology of the ECG and dipole evolution. An algorithm to obtain the location of the stimulus from a 64-lead ECG system was developed. The algorithm presented had a success rate of 93%, meaning that it correctly identified the origin of atrial focus in 75/80 simulations, and involved a general approach relevant to any multi-lead ECG system. This represents a significant improvement over previously developed algorithms

    A matrix isolation and computational study of molecular palladium fluorides : does PdF₆ exist?

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    Palladium atoms generated by thermal evaporation and laser ablation were reacted with and trapped in F₂ /Ar, F₂ /Ne, and neat F₂ matrices. The products were characterized by electronic absorption and infrared spectroscopy, together with relativistic density functional theory calculations as well as coupled cluster calculations. Vibrational modes at 540 and 617 cm⁻¹ in argon matrices were assigned to molecular PdF and PdF₂ , and a band at 692 cm⁻¹ was assigned to molecular PdF₄ . A band at 624 cm⁻¹ can be assigned to either PdF₃ or PdF₆, with the former preferred from experimental considerations. Although calculations might support the latter assignment, our conclusion is that in these detailed experiments there is no convincing evidence for PdF₆

    Orbital angular momentum exchange in an optical parametric oscillator

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    We present a study of orbital angular momentum transfer from pump to down-converted beams in a type-II Optical Parametric Oscillator. Cavity and anisotropy effects are investigated and demostrated to play a central role in the transverse mode dynamics. While the idler beam can oscillate in a Laguerre-Gauss mode, the crystal birefringence induces an astigmatic effect in the signal beam that prevents the resonance of such mode.Comment: 10 pages, 8 figures, regular articl
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