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161.
Rita Simões Christoph Mönninghoff Martha Dlugaj Christian Weimar Isabel Wanke Anne-Marie van Cappellen van Walsum Cornelis Slump 《Magnetic resonance imaging》2013
Magnetic Resonance (MR) white matter hyperintensities have been shown to predict an increased risk of developing cognitive decline. However, their actual role in the conversion to dementia is still not fully understood. Automatic segmentation methods can help in the screening and monitoring of Mild Cognitive Impairment patients who take part in large population-based studies. Most existing segmentation approaches use multimodal MR images. However, multiple acquisitions represent a limitation in terms of both patient comfort and computational complexity of the algorithms. In this work, we propose an automatic lesion segmentation method that uses only three-dimensional fluid-attenuation inversion recovery (FLAIR) images. We use a modified context-sensitive Gaussian mixture model to determine voxel class probabilities, followed by correction of FLAIR artifacts. We evaluate the method against the manual segmentation performed by an experienced neuroradiologist and compare the results with other unimodal segmentation approaches. Finally, we apply our method to the segmentation of multiple sclerosis lesions by using a publicly available benchmark dataset. Results show a similar performance to other state-of-the-art multimodal methods, as well as to the human rater. 相似文献
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163.
Linghai Lu D. J. Murray-Smith E. W. McGookin 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(5):437-454
This paper describes the use of inverse simulation to develop feedforward controllers for model-based output-tracking control system structures, thus avoiding the more complicated techniques of model inversion. Similarities and shortcomings of the inverse simulation and model inversion approaches are explored. It is found that, with suitable values of discretized time interval, the method based on inverse simulation may be preferable for minimum-phase systems. Depending upon zero redistribution within the process of inverse simulation, non-minimum-phase problems for linear systems can also be handled. The conclusions are demonstrated using a non-linear HS125 aircraft model, a linearised Lynx helicopter model and a container ship model for ship steering control and roll stabilization. 相似文献
164.
Ke Bo Lu 《数学学报(英文版)》2013,29(11):2181-2192
In this paper, we study the combinatorial properties ol words m chscrete dynamical systems from antisymmetric cubic maps. We also discuss the relationship of primitive kneading sequences of length n and period-doubling kneading sequences of length 2n, and then determine the number of all kneading sequences of length n. 相似文献
165.
Hansen MR Brorson M Bildsøe H Skibsted J Jakobsen HJ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,190(2):316-326
The WURST (wideband uniform rate smooth truncation) and hyperbolic secant (HS) pulse elements have each been employed as pairs of inversion pulses to induce population transfer (PT) between the four energy levels in natural abundance solid-state (33)S (spin I=3/2) MAS NMR, thereby leading to a significant gain in intensity for the central transition (CT). The pair of inversion pulses are applied to the satellite transitions for a series of inorganic sulfates, the sulfate ions in the two cementitious materials ettringite and thaumasite, and the two tetrathiometallates (NH(4))(2)WS(4) and (NH(4))(2)MoS(4). These materials all exhibit (33)S quadrupole coupling constants (C(Q)) in the range 0.1-1.0 MHz, with precise C(Q) values being determined from analysis of the PT enhanced (33)S MAS NMR spectra. The enhancement factors for the WURST and HS elements are quite similar and are all in the range 1.74-2.25 for the studied samples, in excellent agreement with earlier reports on HS enhancement factors (1.6-2.4) observed for other spin I=3/2 nuclei with similar C(Q) values (0.3-1.2 MHz). Thus, a time saving in instrument time by a factor up to five has been achieved in natural abundance (33)S MAS NMR, a time saving which is extremely welcome for this important low-gamma nucleus. 相似文献
166.
Temperature-depended handedness inversion in chiral mesoporous silica was investigated by diffuse-reflectance circular dichroism spectra. 相似文献
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169.
The interest in the low energy self-emulsification techniques has exploded in the recent years, driven by three main trends: by the transition to “greener” technologies in both its aspects—less energy consumption and replacement of the petrochemicals by natural ingredients; by the costly and maintenance demanding equipment for nanoemulsification; and by the quest for efficient and robust self-emulsifying formulations for oral drug delivery. Here, we first present a brief overview of the main known low-energy methods for nanoemulsion formation, focusing on their mechanistic understanding and discussing some recent advances in their development and applications. Next, we review three conceptually new approaches for self-emulsification in chemical technologies, discovered in the last several years. The colloidal features and the specific requirements of the self-emulsifying drug-delivery systems (SEDDS) are also discussed briefly. Finally, we summarize the current trends and the main challenges in this vivid research area. 相似文献
170.
Angshuman Ghosh Soumen Kumar Dubey Dr. Maxcimilan Patra Jishu Mandal Narendra Nath Ghosh Priyanka Das Arpita Bhowmick Dr. Keka Sarkar Dr. Suprabhat Mukherjee Rajat Saha Dr. Subham Bhattacharjee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(63):e202201621
We have shown solvent- and substrate-dependent chiral inversion of a few glycoconjugate supramolecules. (Z)-F-Gluco, in which d -glucosamine has been attached chemically to Cbz-protected l -phenylalanine at the C terminus, forms a self-healing hydrogel through intertwining of the nanofibers wherein the gelators undergo lamellar packing in the β-sheet secondary structures with a single chiral handedness. Dihybrid (Z)-F-gluco nanocomposite gel was prepared by in-situ formation of silver nanoparticles AgNPs in the gel; this enhances the mechanical properties of the composite gel through physical crosslinking without altering the packing pattern. In contrast, (Z)-L-gluco bearing an l -leucine moiety does not form a hydrogel but an organogel. Interestingly, the chiral handedness of the aggregates of (Z)-L-gluco can be reversed by choosing suitable solvents. In addition to self-healing behavior, (Z)-L-gluco gel revealed shape persistency. Further, (Z)-F-gluco hydrogel is benign, nontoxic, non-immunogenic, and non-allergenic in animal cells. AgNP-loaded (Z)-F-gluco hydrogel showed antibacterial activity against both Gram-positive and Gram-negative bacteria. 相似文献