Patients undergoing Magnetic Resonance Imaging (MRI) are exposed to strong, non-uniform static magnetic fields outside of the central imaging region, in which the movement of the body may induce electric currents in t...Patients undergoing Magnetic Resonance Imaging (MRI) are exposed to strong, non-uniform static magnetic fields outside of the central imaging region, in which the movement of the body may induce electric currents in tissues which could possibly be harmful. The purpose of this study was to re-evaluate existing clinical protocols by determining the induced electromagnetic (EM) fields in MRI spine examinations. The study covered 120 MRI spine examinations at the MRI Unit of a hospital in Accra, Ghana. A numerical model based on Faraday’s equation was developed using the finite difference method (FDM) and MATLAB software to compute, first, a test simulation of induced EM field intensities and then actual measurements of induced fields on the spine. The simulation results were peak induced electric field, 0.39 V/m and current density, 0.039 A/m2. Patient results were;calculated maximum velocity, 0.29 m/s;peak induced electric field strength, 0.44 V/m, and current density, 0.043 A/m2. The levels of induced EM-fields were such that they would not pose any potential health hazards to the patients as these values were well below the recommended guidance levels set by the Directive IEC 60601-2-33 of the European Parliament.展开更多
Buerger’s disease, also called thromboangiitis obliterans (TAO), is an inflammatory disease affecting small and medium size blood vessels of the limbs. Several risk factors are strongly associated with this disease. ...Buerger’s disease, also called thromboangiitis obliterans (TAO), is an inflammatory disease affecting small and medium size blood vessels of the limbs. Several risk factors are strongly associated with this disease. In fact, heavy smokers represent 99% of patients diagnosed with Buerger’s disease and smoking cessation can slow down the progression of the pathology. Ulcers and gangrene are very common complications and TAO may also cause a vasculitis as well as ischemic damage to the distal part of the limbs that can eventually lead to limb amputation. Here, we report the case of a 43 years old patient, a flight personnel working in a Tunisian airline company who consults for a lesion of the left toe that appeared 2 weeks ago. He is a chronic inveterate smoker with 36 pack-years. The diagnosis of TAO was made based on the clinical presentation and the results of the Doppler Ultrasound of the left toe. This disease has a major impact on the quality of life due to the risk of necrotic ulcers and amputation. Navigation is a profession that requires a high level of physical and mental fitness. According to the international and Tunisian standards, the applicant or the holder of medical certificate must not have a cardiovascular condition that may affect the safety of the exercise.展开更多
16 S r RNA序列分析作为微生物系统分类的主要依据已得到广泛认同 ,随着微生物核糖体RNA数据库的日臻完善 ,该技术成为细菌分类和鉴定的一个有力工具。本文总结了 16 S r RNA作为海洋微生物系统分子分类鉴定的理论基础和具体方法 ,分析...16 S r RNA序列分析作为微生物系统分类的主要依据已得到广泛认同 ,随着微生物核糖体RNA数据库的日臻完善 ,该技术成为细菌分类和鉴定的一个有力工具。本文总结了 16 S r RNA作为海洋微生物系统分子分类鉴定的理论基础和具体方法 ,分析了用 16 S r RNA研究海洋微生物的进化关系 ,并且对 16 S r展开更多
文摘Patients undergoing Magnetic Resonance Imaging (MRI) are exposed to strong, non-uniform static magnetic fields outside of the central imaging region, in which the movement of the body may induce electric currents in tissues which could possibly be harmful. The purpose of this study was to re-evaluate existing clinical protocols by determining the induced electromagnetic (EM) fields in MRI spine examinations. The study covered 120 MRI spine examinations at the MRI Unit of a hospital in Accra, Ghana. A numerical model based on Faraday’s equation was developed using the finite difference method (FDM) and MATLAB software to compute, first, a test simulation of induced EM field intensities and then actual measurements of induced fields on the spine. The simulation results were peak induced electric field, 0.39 V/m and current density, 0.039 A/m2. Patient results were;calculated maximum velocity, 0.29 m/s;peak induced electric field strength, 0.44 V/m, and current density, 0.043 A/m2. The levels of induced EM-fields were such that they would not pose any potential health hazards to the patients as these values were well below the recommended guidance levels set by the Directive IEC 60601-2-33 of the European Parliament.
文摘Buerger’s disease, also called thromboangiitis obliterans (TAO), is an inflammatory disease affecting small and medium size blood vessels of the limbs. Several risk factors are strongly associated with this disease. In fact, heavy smokers represent 99% of patients diagnosed with Buerger’s disease and smoking cessation can slow down the progression of the pathology. Ulcers and gangrene are very common complications and TAO may also cause a vasculitis as well as ischemic damage to the distal part of the limbs that can eventually lead to limb amputation. Here, we report the case of a 43 years old patient, a flight personnel working in a Tunisian airline company who consults for a lesion of the left toe that appeared 2 weeks ago. He is a chronic inveterate smoker with 36 pack-years. The diagnosis of TAO was made based on the clinical presentation and the results of the Doppler Ultrasound of the left toe. This disease has a major impact on the quality of life due to the risk of necrotic ulcers and amputation. Navigation is a profession that requires a high level of physical and mental fitness. According to the international and Tunisian standards, the applicant or the holder of medical certificate must not have a cardiovascular condition that may affect the safety of the exercise.
文摘16 S r RNA序列分析作为微生物系统分类的主要依据已得到广泛认同 ,随着微生物核糖体RNA数据库的日臻完善 ,该技术成为细菌分类和鉴定的一个有力工具。本文总结了 16 S r RNA作为海洋微生物系统分子分类鉴定的理论基础和具体方法 ,分析了用 16 S r RNA研究海洋微生物的进化关系 ,并且对 16 S r
