Search results for "DISPERSION"
showing 10 items of 1101 documents
Challenges in dental statistics: data and modelling
2022
The aim of this work is to present the reflections and proposals derived from the first Workshop of the SISMEC STATDENT working group on statistical methods and applications in dentistry, held in Ancona (Italy) on 28th September 2011. STATDENT began as a forum of comparison and discussion for statisticians working in the field of dental research in order to suggest new and improve existing biostatistical and clinical epidemiological methods. During the meeting, we dealt with very important topics of statistical methodology for the analysis of dental data, covering the analysis of hierarchically structured and over-dispersed data, the issue of calibration and reproducibility, as well as some…
Structural characterization and optical constants of p-toluene sulfonic acid doped polyaniline and its composites of chitosan and reduced graphene-ox…
2020
Para-Toluene sulfonic acid doped polyaniline (PANI), PANI/chitosan composites, PANI/reduced graphene-oxide composites and a ternary composite comprising of PANI, chitosan and reduced graphene-oxide have synthesised via oxidative polymerisation of aniline by Ammonium peroxydisulfate (APS). FTIR, XRD, FESEM and UV-VIS techniques were performed for the confirmation of the successful synthesis. The fundamental optical parameters such as, complex refractive index, complex dielectric constants and optical conductivity of the PANI and the composites were investigated in the UV-VIS-NIR range. The results show a clear dependence on the constituent component such as sulphur as well as the absorbance …
The Instability of Ni{N(SiMe3)2}2: A Fifty Year Old Transition Metal Silylamide Mystery
2015
The characterization of the unstable NiII bis(silylamide) Ni{N(SiMe3)2}2 (1), its THF complex Ni{N(SiMe3)2}2(THF) (2), and the stable bis(pyridine) derivative trans-Ni{N(SiMe3)2}2(py)2 (3), is described. Both 1 and 2 decompose at ca. 25 °C to a tetrameric NiI species, [Ni{N(SiMe3)2}]4 (4), also obtainable from LiN(SiMe3)2 and NiCl2(DME). Experimental and computational data indicate that the instability of 1 is likely due to ease of reduction of NiII to NiI and the stabilization of 4 through dispersion forces. peerReviewed
Spin Wave Emission from Vortex Cores under Static Magnetic Bias Fields
2021
We studied the influence of a static in-plane magnetic field on the alternating-field-driven emission of nanoscale spin waves from magnetic vortex cores. Time-resolved scanning transmission X-ray microscopy was used to image spin waves in disk structures of synthetic ferrimagnets and single ferromagnetic layers. For both systems, it was found that an increasing magnetic bias field continuously displaces the wave-emitting vortex core from the center of the disk toward its edge without noticeably altering the spin-wave dispersion relation. In the case of the single-layer disk, an anisotropic lateral expansion of the core occurs at higher magnetic fields, which leads to a directional rather th…
Studying hypertension in ocular fundus images using Hausdorff dispersion ordering.
2010
Retinal arterial and vein diameters are altered in individuals at risk of cardiovascular events mainly due to high blood pressure. The measurement of retinal vessel diameters has been proved to reflect individuals' vascular health. Dispersion of such measures which are obtained by means of ocular fundus images is a major factor not usually considered in clinical research. In this paper, a method to evaluate if different levels of clinically relevant covariables induce greater dispersion in retinal arterial and vein diameters is proposed. A multivariate dispersion ordering, the Hausdorff dispersion order, is used to compare the level of dispersion in such diameters for different groups of pa…
Quantitative myocardial perfusion magnetic resonance imaging: the impact of pulsatile flow on contrast agent bolus dispersion.
2011
Myocardial blood flow (MBF) can be quantified using T1-weighted first-pass magnetic resonance imaging (MRI) in combination with a tracer-kinetic model, like MMID4. This procedure requires the knowledge of an arterial input function which is usually estimated from the left ventricle (LV). Dispersion of the contrast agent bolus may occur between the LV and the tissue of interest. The aim of this study was to investigate the dispersion under conditions of physiological pulsatile blood flow, and to simulate its effect on MBF quantification. The dispersion was simulated in coronary arteries using a computational fluid dynamics (CFD) approach. Simulations were accomplished on straight vessels wit…
Max–min dispersion with capacity and cost for a practical location problem
2022
Diversity and dispersion problems deal with selecting a subset of elements from a given set in such a way that their diversity is maximized. This study considers a practical location problem recently proposed in the context of max–min dispersion models. It is called the generalized dispersion problem, and it models realistic applications by introducing capacity and cost constraints. We propose two effective linear formulations for this problem, and develop a hybrid metaheuristic algorithm based on the variable neighborhood search methodology, to solve real instances. Extensive numerical computational experiments are performed to compare our hybrid metaheuristic with the state-of-art heurist…
Structural studies of dielectric polymer nanocomposites
2013
A constant need for the development of new and superior materials is always present; for example, a better electrical insulator would enable more efficient use of electrical power. Polymeric nanocomposites, i.e. nanodielectrics, are thought to have unique electrical properties. The basic chemical constitution of a material alone fails to provide an understanding of how desired properties of a material originate or predict the long term behavior of a material. We need to define the structure behind the functionality of a material. To do that, the structure of the material must be studied on several scales. This research was part of the Finnish Funding Agency for Technology and Innovation (TE…
Computational Structures and SAPT Interaction Energies of HXeSH···H2Y (Y=O or S) Complexes
2018
Ab initio calculations of the structures, vibrational spectra and supermolecular and symmetry-adapted perturbation theory (SAPT) interaction energies of the HXeOH and HXeSH complexes with H2O and H2S molecules are presented. Two minima already reported in the literature were reproduced and ten new ones were found together with some transition states. All complexes show blue shift in Xe&ndash
Measurement of nonlinear and chromatic dispersion parameters of optical fibers using modulation instability
2006
International audience; We present a simple method for the measurement of Kerr, second- and third-order dispersion coefficients in optical fibers using power and dispersion dependences of modulation instability near the zero-dispersion wavelength. We also complete the analysis by the accurate determination of the zero-dispersion wavelength of the fiber using the phase-matched four wave mixing process which occurs near this specific wavelength.