The electromagnetic fields surrounding the electric and communication installations are blamed not only for cancerigenic effects, but also for negative influences on the natural electrophysiological phenomena and ＂ac...The electromagnetic fields surrounding the electric and communication installations are blamed not only for cancerigenic effects, but also for negative influences on the natural electrophysiological phenomena and ＂accused＂ of causing some degenerative diseases of the nervous system, genetic modifications with hereditary effects, mental and behavioural disturbances. This research aimed to highlight that Directive 2008 / 46 / EC had a series of positive aspects as well as drawbacks. Directive 2008 / 46 / EC of the European Parliament and of the Council amending Directive 2004 / 40 / EC on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents （electromagnetic fields） is criticized because these norms should regard not only the category of those working in different domains, but also the large category of consumers （of cell phones, microwave ovens, computers, etc.）.展开更多
Objective： To investigate the possible age- and sex-related differences in the various dimensions of corpus callosum among Chinese normal adults. Methods： Magnetic resonance images of 286 healthy adults, including 1...Objective： To investigate the possible age- and sex-related differences in the various dimensions of corpus callosum among Chinese normal adults. Methods： Magnetic resonance images of 286 healthy adults, including 127 males and 159 females, and ranging in age from 20 to 81 years, were investigated. They were classified into 5 age groups （ 20-29, 30-39, 40-49, 50-59, and 60-81 years old）. Corresponding to the age group sequence above, the male/female ratio of each group respectively was： 25/26, 26/33, 33/50, 32/36, and 11/14. The following dimensions of corpus callosum were systematically measured on the midsagittal Tl-weighted images： frontal to occipital pole （represented as line segment AB）, total longitudinal dimension of the corpus callosum （CD）, the maximum height （EF）, the widths of the genu （CX）, anterior one third （GH）, central region （EZ）, posterior one third （MN） and splenium （YD）. After that, the obtained data was analyzed statistically. Results： （1） The total longitudinal dimension, maximum height, widths of the genu, central region and splenium were proved to be larger in females. But the widths of the anterior one third and posterior one third were similar in-between. In spite of that, a conspicuous sex-related difference was not found. （2） The total longitudinal dimension and the maximum height of the corpus callosum remained stable in all age subgroups. Yet the widths of the genu, anterior one third, central region, posterior one third and splenium had a tendency of decreasing gradually with aging. Statistical difference was seen in the anterior one third, central region, posterior one third （P〈0.05）. Conclusion： There is no sex-related difference in all dimensions of corpus callosum. But, with aging, a significant difference is found in the widths of the anterior one third, central region and posterior one third.展开更多
We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electri...We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model. Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245±0.0068 and 8.9997%±0.0084%, for hemorrhagic stroke, and 0.6748±0.0197 and 8.8986%±0.0089%, for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans.展开更多
Since neodymium magnet possesses an extremely strong magnetic field, resulting from the combination of neodymium, iron and boron, it has become the most used in designing autonomous sumo robots. When it is mounted und...Since neodymium magnet possesses an extremely strong magnetic field, resulting from the combination of neodymium, iron and boron, it has become the most used in designing autonomous sumo robots. When it is mounted under the structure of this robot, the magnet produces a large amount of normal force resulting from the interaction between its field lines and the steel frame of the arena, reducing the risk of slipping its wheels. Thus, the heavier a robot, the greater the difficulty for the opponent to remove it from the arena. This article explains the properties of Nd-Fe-Br magnets and analyzes the influence of these characteristics in the relation induction/weight. Additionally, to a comparative analysis, this research analyzes the positioning, geometry and polarization of the magnets under study, based on numerical results obtained using Inventor and K ＆ J Magnets Calculator software, given that these factors influence in their energetic product generation. Furthermore, more than just working with what we believe is a subject of great interest for sumo robot＇s teams, this study encourages their competitiveness, an essential factor for the competition.展开更多
文摘The electromagnetic fields surrounding the electric and communication installations are blamed not only for cancerigenic effects, but also for negative influences on the natural electrophysiological phenomena and ＂accused＂ of causing some degenerative diseases of the nervous system, genetic modifications with hereditary effects, mental and behavioural disturbances. This research aimed to highlight that Directive 2008 / 46 / EC had a series of positive aspects as well as drawbacks. Directive 2008 / 46 / EC of the European Parliament and of the Council amending Directive 2004 / 40 / EC on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents （electromagnetic fields） is criticized because these norms should regard not only the category of those working in different domains, but also the large category of consumers （of cell phones, microwave ovens, computers, etc.）.
文摘Objective： To investigate the possible age- and sex-related differences in the various dimensions of corpus callosum among Chinese normal adults. Methods： Magnetic resonance images of 286 healthy adults, including 127 males and 159 females, and ranging in age from 20 to 81 years, were investigated. They were classified into 5 age groups （ 20-29, 30-39, 40-49, 50-59, and 60-81 years old）. Corresponding to the age group sequence above, the male/female ratio of each group respectively was： 25/26, 26/33, 33/50, 32/36, and 11/14. The following dimensions of corpus callosum were systematically measured on the midsagittal Tl-weighted images： frontal to occipital pole （represented as line segment AB）, total longitudinal dimension of the corpus callosum （CD）, the maximum height （EF）, the widths of the genu （CX）, anterior one third （GH）, central region （EZ）, posterior one third （MN） and splenium （YD）. After that, the obtained data was analyzed statistically. Results： （1） The total longitudinal dimension, maximum height, widths of the genu, central region and splenium were proved to be larger in females. But the widths of the anterior one third and posterior one third were similar in-between. In spite of that, a conspicuous sex-related difference was not found. （2） The total longitudinal dimension and the maximum height of the corpus callosum remained stable in all age subgroups. Yet the widths of the genu, anterior one third, central region, posterior one third and splenium had a tendency of decreasing gradually with aging. Statistical difference was seen in the anterior one third, central region, posterior one third （P〈0.05）. Conclusion： There is no sex-related difference in all dimensions of corpus callosum. But, with aging, a significant difference is found in the widths of the anterior one third, central region and posterior one third.
基金Project supported partly by the National Science Foundation (No.BES-0411898) and the National Institues of Health (No. R01EB00178) USA
文摘We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model. Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245±0.0068 and 8.9997%±0.0084%, for hemorrhagic stroke, and 0.6748±0.0197 and 8.8986%±0.0089%, for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans.
文摘Since neodymium magnet possesses an extremely strong magnetic field, resulting from the combination of neodymium, iron and boron, it has become the most used in designing autonomous sumo robots. When it is mounted under the structure of this robot, the magnet produces a large amount of normal force resulting from the interaction between its field lines and the steel frame of the arena, reducing the risk of slipping its wheels. Thus, the heavier a robot, the greater the difficulty for the opponent to remove it from the arena. This article explains the properties of Nd-Fe-Br magnets and analyzes the influence of these characteristics in the relation induction/weight. Additionally, to a comparative analysis, this research analyzes the positioning, geometry and polarization of the magnets under study, based on numerical results obtained using Inventor and K ＆ J Magnets Calculator software, given that these factors influence in their energetic product generation. Furthermore, more than just working with what we believe is a subject of great interest for sumo robot＇s teams, this study encourages their competitiveness, an essential factor for the competition.
