Hemorrhagic transformation is a major complication of large-artery atheroscle rotic stroke(a major ischemic stro ke subtype)that wo rsens outcomes and increases mortality.Disruption of the gut microbiota is an importa...Hemorrhagic transformation is a major complication of large-artery atheroscle rotic stroke(a major ischemic stro ke subtype)that wo rsens outcomes and increases mortality.Disruption of the gut microbiota is an important feature of stroke,and some specific bacteria and bacterial metabolites may contribute to hemorrhagic transformation pathogenesis.We aimed to investigate the relationship between the gut microbiota and hemorrhagic transformation in largearte ry atheroscle rotic stro ke.An observational retrospective study was conducted.From May 2020 to September 2021,blood and fecal samples were obtained upon admission from 32 patients with first-ever acute ischemic stroke and not undergoing intravenous thrombolysis or endovascular thrombectomy,as well as 16 healthy controls.Patients with stro ke who developed hemorrhagic transfo rmation(n=15)were compared to those who did not develop hemorrhagic transformation(n=17)and with healthy controls.The gut microbiota was assessed through 16S ribosomal ribonucleic acid sequencing.We also examined key components of the lipopolysaccharide pathway:lipopolysaccharide,lipopolysaccharide-binding protein,and soluble CD14.We observed that bacterial diversity was decreased in both the hemorrhagic transformation and non-hemorrhagic transfo rmation group compared with the healthy controls.The patients with ischemic stro ke who developed hemorrhagic transfo rmation exhibited altered gut micro biota composition,in particular an increase in the relative abundance and dive rsity of members belonging to the Enterobacteriaceae family.Plasma lipopolysaccharide and lipopolysaccharide-binding protein levels were higher in the hemorrhagic transformation group compared with the non-hemorrhagic transfo rmation group.lipopolysaccharide,lipopolysaccharide-binding protein,and soluble CD14 concentrations were associated with increased abundance of Enterobacte riaceae.Next,the role of the gut microbiota in hemorrhagic transformation was evaluated using an experimental stroke rat model.In this model,transplantation of the gut microbiota from hemorrhagic transformation rats into the recipient rats triggered higher plasma levels of lipopolysaccharide,lipopolysaccharide-binding protein,and soluble CD14.Ta ken togethe r,our findings demonstrate a noticeable change in the gut microbiota and lipopolysaccharide-related inflammatory response in stroke patients with hemorrhagic transformation.This suggests that maintaining a balanced gut microbiota may be an important factor in preventing hemorrhagic transfo rmation after stro ke.展开更多
Ischemic stroke is an important disease leading to death and disability for all human beings, and the key to its treatment lies in the early opening of obstructed vessels and restoration of perfusion to the local infa...Ischemic stroke is an important disease leading to death and disability for all human beings, and the key to its treatment lies in the early opening of obstructed vessels and restoration of perfusion to the local infarcted area. Intravenous thrombolysis with tissue plasminogen activator (tPA) is one of the effective therapies to achieve revascularization, but it faces strict indications with a narrow therapeutic time window, and significantly increases the incidence of hemorrhagic transformation, HT, after reperfusion of the infarcted foci, which greatly reduces the incidence of patients with ischemic stroke. which significantly increases the incidence of hemorrhagic transformation (HT) after reperfusion of the infarcted focus, greatly reducing patient utilization and clinical benefit. Since the mechanism of HT has not been fully elucidated, and the related molecular mechanisms are complex and interactive, there is no specific and effective therapy to avoid the occurrence of HT. In this article, we focus on the research progress on the mechanism of HT after tPA intravenous thrombolysis in ischemic stroke patients from the aspects of vascular integrity disruption, oxidative stress, and neuroinflammatory response and the corresponding therapeutic strategies, in order to improve the safety and prognosis of tPA intravenous thrombolysis in the clinic.展开更多
Background: To study the influence of blood lipid levels on hemorrhagic transformation(HT) and prognosis after acute cerebral infarction(ACI).Methods: Patients with ACI within 72 h of symptoms onset between January 1 ...Background: To study the influence of blood lipid levels on hemorrhagic transformation(HT) and prognosis after acute cerebral infarction(ACI).Methods: Patients with ACI within 72 h of symptoms onset between January 1 st, 2015, and December 31 st, 2016, were retrospectively analyzed. Patients were divided into group A(without HT) and group B(HT). The outcomes were assessed after 3 months of disease onset using the modified Rankin Scale(m RS). An m RS score of 0–2 points indicated excellent prognosis, and an m RS score of 3–6 points indicated poor prognosis.Results: A total of 732 patients conformed to the inclusion criteria, including 628 in group A and 104 in group B. The incidence of HT was 14.2%, and the median onset time was 2 d(interquartile range, 1–7 d). The percentages of patients with large infarct size and cortex involvement in group B were 80.8% and 79.8%, respectively, which were both significantly higher than those in group A(28.7 and 33.4%, respectively). The incidence rate of atrial fibrillation(AF) in group B was significantly higher than that in group A(39.4% vs. 13.9%, P<0.001). The adjusted multivariate analysis results showed that large infarct size, cortex involvement and AF were independent risk factors of HT, while total cholesterol(TC) was a protective factor of HT(OR=0.359, 95% CI 0.136–0.944, P=0.038). With every 1 mmol/L reduction in normal TC levels, the risk of HT increased by 64.1%. The mortality and morbidity at 3 months in group B(21.2% and 76.7%, respectively) were both significantly higher than those in group A(8.0% and 42.8%, respectively). The adjusted multivariate analysis results showed that large infarct size(OR=12.178, 95% CI 5.390–27.516, P<0.001) was an independent risk factor of long-term unfavorable outcomes, whereas low-density lipoprotein cholesterol(LDL-C) was a protective factor(OR=0.538, 95% CI 0.300–0.964, P=0.037). With every 1 mmol/L reduction in normal LDL-C levels, the risk of an unfavorable outcome increased by 46.2%. Major therapies, including intravenous recombinant human tissue plasminogen activator(r TPA), intensive lipid-lowering statins and anti-platelets, were not significantly related to either HT or long-term, post-ACI poor prognosis.Conclusions: For patients with large infarct sizes, especially those with cortex involvement, AF, or lower levels of TC, the risk of HT might increase after ACI. The risk of a long-term unfavorable outcome in these patients might increase with a reduction in LDL-C.展开更多
BACKGROUND Cerebral proliferative angiopathy(CPA)is a rare vascular disease characterized by the presence of diffuse vascular proliferation,progressive vascular hyperflow and vasodilation of multiple vessels in the no...BACKGROUND Cerebral proliferative angiopathy(CPA)is a rare vascular disease characterized by the presence of diffuse vascular proliferation,progressive vascular hyperflow and vasodilation of multiple vessels in the normal brain parenchyma.Unlike cerebral arteriovenous malformations,CPA has a mixed appearance between that of lesions with cell proliferation and endothelial proliferation.To date,the pathogenesis of CPA is unclear,in which changes induced by cortical ischemia in the elastic layer of the blood supply artery and smooth muscle cells may be involved.CASE SUMMARY In this article,we retrospectively analyzed a case of hemorrhagic transformation of ischemic CPA diagnosed by digital subtraction angiography and reviewed the related literature for further exploration of its pathogenesis,diagnosis and treatment.CONCLUSION The information in the present case report may facilitate further clinical research on this cerebrovascular disease.展开更多
BACKGROUNDPolycythemia vera (PV) is a chronic myeloproliferative disorder characterized byan increase in red blood cells in the peripheral blood. Previous work has reportedthe occurrence of thrombosis or hemorrhage ar...BACKGROUNDPolycythemia vera (PV) is a chronic myeloproliferative disorder characterized byan increase in red blood cells in the peripheral blood. Previous work has reportedthe occurrence of thrombosis or hemorrhage arising in the cerebral vasculaturesecondary to PV. However, hemorrhagic transformation after PV-associated acuteischemic stroke has not been previously described.CASE SUMMARYWe herein present two cases of PV where hemorrhagic transformation occurredafter an acute ischemic stroke. Case 1 was a 57-year-old woman with a history ofhypertension who was admitted for left-sided weakness. Case 2 was a 68-year-oldman who was admitted for a 10-d sudden left arm weakness. Imaging examinationsfor the two patients revealed hemorrhagic transformation after acuteischemic stroke. Both patients had JAK-2-V617F mutation and receivedantiplatelet therapy. Both of them had a good prognosis during the follow-up.CONCLUSIONThis report suggested that hemorrhagic transformation may occur in acuteischemic stroke caused by PV. Antiplatelet drugs do not seem to influence thelong-term outcomes in such patients. Future research should focus on establishinga standard antiplatelet treatment strategy for this condition.展开更多
Objective:To study the risk factors of hemorrhagic transformation in patients with acute cerebral infarction and to analyze the risk factors.Methods: A total of 96 patients with acute cerebral infarction after the thr...Objective:To study the risk factors of hemorrhagic transformation in patients with acute cerebral infarction and to analyze the risk factors.Methods: A total of 96 patients with acute cerebral infarction after the thrombolysis in our hospital from June 2016 to December 2017 were selected as the research object. And they were divided into bleeding group 48 cases and hemorrhage transformation group 48 cases according to whether with hemorrhage occurs transformation. Then the lipid metabolism, atrial fibrillation, history of smoking and drinking, history of hypertension and diabetes, blood pressure, treatment time after onset and infarction area of two groups were compared, and the relationship between those factors and the disease were analyzed by the multi-factor Logistic regression analysis.Results: The atrial fibrillation, history of smoking and drinking of two groups had significant differences;The hospital fasting plasma glucose and LDL-C level of two groups had significant differences;the treatment time after onset and infarction area of two groups had significant differences;The multi-factor Logistic regression analysis showed that atrial fibrillation, blood glucose on admission, LDL-C and large area of infarction are the factors affecting the risk of bleeding in patients with acute cerebral infarction transformation.Conclusion:Atrial fibrillation, blood glucose on admission, LDL-C, treatment time after onset and large area of infarction belongs to the patients with acute cerebral infarction after the thrombolysis transformation of bleeding risk factors.展开更多
To compare the early effects of hypertonic and isotonic saline resuscitation on heme oxygenase-1 (HO-1) expression in organs of rats with hemorrhagic shock. Rats were randomly divided into hypertonic saline resuscit...To compare the early effects of hypertonic and isotonic saline resuscitation on heme oxygenase-1 (HO-1) expression in organs of rats with hemorrhagic shock. Rats were randomly divided into hypertonic saline resuscitation (HTS), normal saline resuscitation (NS) and sham groups. HO-1 mRNA, protein expression and apoptosis were evaluated in organs. In the HTS group, significant difference was noted in HO-1 protein in small intestinal mucosa and liver compared with the NS and sham groups, and in HO-1 mRNA in liver and kidney compared with the sham group. The apoptosis of small intestinal mucosa, liver, heart, and lung was significantly lower in the HTS group than that in the NS group. In this study, small volume resuscitation with HTS can efficiently up-regulate the expression level of HO-1 in small intestinal mucosa and liver, which may be one of the mechanisms alleviating organ damage.展开更多
The observations of in-situ spacecraft mission in the magnetosheath and a region of thermalized subsonic plasma behind the bow shock reveal a non-linear behaviour of plasma waves. The study of waves and optics in Phys...The observations of in-situ spacecraft mission in the magnetosheath and a region of thermalized subsonic plasma behind the bow shock reveal a non-linear behaviour of plasma waves. The study of waves and optics in Physics has given the understanding of the effect of many waves coming together to form a wave field or wave packet. The common aspect of such study shows that two or more waves can superimpose constructively or destructively. The sudden high magnetic field data in the magnetosheath displays such possibility of superposition of waves. In this paper, we use the empirical mode decomposition (EMD) and Hilbert transform (HT) techniques to determine the instantaneous frequencies of low frequency plasma waves in the magnetosheath. Our analysis has shown that the turbulent behavior of magnetic field in the magnetosheath within the selected period is due to superposition of waves.展开更多
With the improvement of high temperature superconductor (HTS) practical performance, research and development concerning the applications of HTS transformers have been progressed actively worldwide. This paper provi...With the improvement of high temperature superconductor (HTS) practical performance, research and development concerning the applications of HTS transformers have been progressed actively worldwide. This paper provides a comprehensive summary on various HTS transformers, and studies the design of a single-phase 10 kVA (220V/24V) HTS transformer prototype to verify HTS for practical transformer applications.展开更多
目的分析亚甲基四氢叶酸还原酶(MTHFR)基因多态性对脑梗死患者阿替普酶静脉溶栓后出血性转化(HT)的影响。方法回顾性分析2020年7月—2023年7月在安徽医科大学附属阜阳人民医院接受治疗的120例脑梗死患者的临床资料。依据治疗后24~72 h H...目的分析亚甲基四氢叶酸还原酶(MTHFR)基因多态性对脑梗死患者阿替普酶静脉溶栓后出血性转化(HT)的影响。方法回顾性分析2020年7月—2023年7月在安徽医科大学附属阜阳人民医院接受治疗的120例脑梗死患者的临床资料。依据治疗后24~72 h HT发生情况分为HT组(15例)、无HT组(105例)。比较两组基线资料、MTHFR基因多态性、纤维蛋白原(Fib)、同型半胱氨酸(Hcy)。采用多因素一般Logistic回归模型分析脑梗死患者阿替普酶静脉溶栓后HT发生的危险因素。绘制受试者工作特征(ROC)曲线,分析入院时美国国立卫生院卒中量表(NIHSS)评分、Hcy预测脑梗死患者阿替普酶静脉溶栓后HT发生的价值。结果HT组心房颤动发生率、MTHFR基因型677CT占比、入院时NIHSS评分、Hcy水平均高于无HT组(P<0.05)。多因素一般Logistic回归分析结果显示:心房颤动史[OR=1.478(95%CI:1.126,1.940)]、入院时NIHSS评分升高[OR=1.656(95%CI:1.125,2.438)]、MTHFR基因型为677CT[OR=1.871/2.362(95%CI:1.052,3.328/1.081,4.652)]、Hcy水平升高[OR=2.149(95%CI:1.108,4.168)]均为脑梗死患者阿替普酶静脉溶栓后HT发生的危险因素(P<0.05)。ROC曲线分析结果显示,入院时NIHSS评分、Hcy均可预测脑梗死患者阿替普酶静脉溶栓后HT发生,其敏感性分别为80.0%(95%CI:0.765,0.883)、73.3%(95%CI:0.717,0.834),特异性分别为74.3%(95%CI:0.659,0.817)、74.3%(95%CI:0.824,0.931)。677CT型患者Hcy水平高于677CC、677TT型患者(P<0.05)。结论心房颤动、MTHFR基因型、入院时NIHSS评分、Hcy均为影响脑梗死患者阿替普酶静脉溶栓后HT发生的重要因素,临床应结合以上指标对高危患者进行重点筛查,尽早采取干预措施。展开更多
基金supported by the National Key Research and Development Projects,Nos.2022 YFC3602400,2022 YFC3602401(to JX)the Project Program of National Clinical Research Center for Geriatric Disorders(Xiangya Hospital),No.2020LNJJ16(to JX)the National Natural Science Foundation of China,No.82271369(to JX)。
文摘Hemorrhagic transformation is a major complication of large-artery atheroscle rotic stroke(a major ischemic stro ke subtype)that wo rsens outcomes and increases mortality.Disruption of the gut microbiota is an important feature of stroke,and some specific bacteria and bacterial metabolites may contribute to hemorrhagic transformation pathogenesis.We aimed to investigate the relationship between the gut microbiota and hemorrhagic transformation in largearte ry atheroscle rotic stro ke.An observational retrospective study was conducted.From May 2020 to September 2021,blood and fecal samples were obtained upon admission from 32 patients with first-ever acute ischemic stroke and not undergoing intravenous thrombolysis or endovascular thrombectomy,as well as 16 healthy controls.Patients with stro ke who developed hemorrhagic transfo rmation(n=15)were compared to those who did not develop hemorrhagic transformation(n=17)and with healthy controls.The gut microbiota was assessed through 16S ribosomal ribonucleic acid sequencing.We also examined key components of the lipopolysaccharide pathway:lipopolysaccharide,lipopolysaccharide-binding protein,and soluble CD14.We observed that bacterial diversity was decreased in both the hemorrhagic transformation and non-hemorrhagic transfo rmation group compared with the healthy controls.The patients with ischemic stro ke who developed hemorrhagic transfo rmation exhibited altered gut micro biota composition,in particular an increase in the relative abundance and dive rsity of members belonging to the Enterobacteriaceae family.Plasma lipopolysaccharide and lipopolysaccharide-binding protein levels were higher in the hemorrhagic transformation group compared with the non-hemorrhagic transfo rmation group.lipopolysaccharide,lipopolysaccharide-binding protein,and soluble CD14 concentrations were associated with increased abundance of Enterobacte riaceae.Next,the role of the gut microbiota in hemorrhagic transformation was evaluated using an experimental stroke rat model.In this model,transplantation of the gut microbiota from hemorrhagic transformation rats into the recipient rats triggered higher plasma levels of lipopolysaccharide,lipopolysaccharide-binding protein,and soluble CD14.Ta ken togethe r,our findings demonstrate a noticeable change in the gut microbiota and lipopolysaccharide-related inflammatory response in stroke patients with hemorrhagic transformation.This suggests that maintaining a balanced gut microbiota may be an important factor in preventing hemorrhagic transfo rmation after stro ke.
文摘Ischemic stroke is an important disease leading to death and disability for all human beings, and the key to its treatment lies in the early opening of obstructed vessels and restoration of perfusion to the local infarcted area. Intravenous thrombolysis with tissue plasminogen activator (tPA) is one of the effective therapies to achieve revascularization, but it faces strict indications with a narrow therapeutic time window, and significantly increases the incidence of hemorrhagic transformation, HT, after reperfusion of the infarcted foci, which greatly reduces the incidence of patients with ischemic stroke. which significantly increases the incidence of hemorrhagic transformation (HT) after reperfusion of the infarcted focus, greatly reducing patient utilization and clinical benefit. Since the mechanism of HT has not been fully elucidated, and the related molecular mechanisms are complex and interactive, there is no specific and effective therapy to avoid the occurrence of HT. In this article, we focus on the research progress on the mechanism of HT after tPA intravenous thrombolysis in ischemic stroke patients from the aspects of vascular integrity disruption, oxidative stress, and neuroinflammatory response and the corresponding therapeutic strategies, in order to improve the safety and prognosis of tPA intravenous thrombolysis in the clinic.
文摘Background: To study the influence of blood lipid levels on hemorrhagic transformation(HT) and prognosis after acute cerebral infarction(ACI).Methods: Patients with ACI within 72 h of symptoms onset between January 1 st, 2015, and December 31 st, 2016, were retrospectively analyzed. Patients were divided into group A(without HT) and group B(HT). The outcomes were assessed after 3 months of disease onset using the modified Rankin Scale(m RS). An m RS score of 0–2 points indicated excellent prognosis, and an m RS score of 3–6 points indicated poor prognosis.Results: A total of 732 patients conformed to the inclusion criteria, including 628 in group A and 104 in group B. The incidence of HT was 14.2%, and the median onset time was 2 d(interquartile range, 1–7 d). The percentages of patients with large infarct size and cortex involvement in group B were 80.8% and 79.8%, respectively, which were both significantly higher than those in group A(28.7 and 33.4%, respectively). The incidence rate of atrial fibrillation(AF) in group B was significantly higher than that in group A(39.4% vs. 13.9%, P<0.001). The adjusted multivariate analysis results showed that large infarct size, cortex involvement and AF were independent risk factors of HT, while total cholesterol(TC) was a protective factor of HT(OR=0.359, 95% CI 0.136–0.944, P=0.038). With every 1 mmol/L reduction in normal TC levels, the risk of HT increased by 64.1%. The mortality and morbidity at 3 months in group B(21.2% and 76.7%, respectively) were both significantly higher than those in group A(8.0% and 42.8%, respectively). The adjusted multivariate analysis results showed that large infarct size(OR=12.178, 95% CI 5.390–27.516, P<0.001) was an independent risk factor of long-term unfavorable outcomes, whereas low-density lipoprotein cholesterol(LDL-C) was a protective factor(OR=0.538, 95% CI 0.300–0.964, P=0.037). With every 1 mmol/L reduction in normal LDL-C levels, the risk of an unfavorable outcome increased by 46.2%. Major therapies, including intravenous recombinant human tissue plasminogen activator(r TPA), intensive lipid-lowering statins and anti-platelets, were not significantly related to either HT or long-term, post-ACI poor prognosis.Conclusions: For patients with large infarct sizes, especially those with cortex involvement, AF, or lower levels of TC, the risk of HT might increase after ACI. The risk of a long-term unfavorable outcome in these patients might increase with a reduction in LDL-C.
基金Supported by National Natural Science Foundation of China,No.81771154.
文摘BACKGROUND Cerebral proliferative angiopathy(CPA)is a rare vascular disease characterized by the presence of diffuse vascular proliferation,progressive vascular hyperflow and vasodilation of multiple vessels in the normal brain parenchyma.Unlike cerebral arteriovenous malformations,CPA has a mixed appearance between that of lesions with cell proliferation and endothelial proliferation.To date,the pathogenesis of CPA is unclear,in which changes induced by cortical ischemia in the elastic layer of the blood supply artery and smooth muscle cells may be involved.CASE SUMMARY In this article,we retrospectively analyzed a case of hemorrhagic transformation of ischemic CPA diagnosed by digital subtraction angiography and reviewed the related literature for further exploration of its pathogenesis,diagnosis and treatment.CONCLUSION The information in the present case report may facilitate further clinical research on this cerebrovascular disease.
文摘BACKGROUNDPolycythemia vera (PV) is a chronic myeloproliferative disorder characterized byan increase in red blood cells in the peripheral blood. Previous work has reportedthe occurrence of thrombosis or hemorrhage arising in the cerebral vasculaturesecondary to PV. However, hemorrhagic transformation after PV-associated acuteischemic stroke has not been previously described.CASE SUMMARYWe herein present two cases of PV where hemorrhagic transformation occurredafter an acute ischemic stroke. Case 1 was a 57-year-old woman with a history ofhypertension who was admitted for left-sided weakness. Case 2 was a 68-year-oldman who was admitted for a 10-d sudden left arm weakness. Imaging examinationsfor the two patients revealed hemorrhagic transformation after acuteischemic stroke. Both patients had JAK-2-V617F mutation and receivedantiplatelet therapy. Both of them had a good prognosis during the follow-up.CONCLUSIONThis report suggested that hemorrhagic transformation may occur in acuteischemic stroke caused by PV. Antiplatelet drugs do not seem to influence thelong-term outcomes in such patients. Future research should focus on establishinga standard antiplatelet treatment strategy for this condition.
文摘Objective:To study the risk factors of hemorrhagic transformation in patients with acute cerebral infarction and to analyze the risk factors.Methods: A total of 96 patients with acute cerebral infarction after the thrombolysis in our hospital from June 2016 to December 2017 were selected as the research object. And they were divided into bleeding group 48 cases and hemorrhage transformation group 48 cases according to whether with hemorrhage occurs transformation. Then the lipid metabolism, atrial fibrillation, history of smoking and drinking, history of hypertension and diabetes, blood pressure, treatment time after onset and infarction area of two groups were compared, and the relationship between those factors and the disease were analyzed by the multi-factor Logistic regression analysis.Results: The atrial fibrillation, history of smoking and drinking of two groups had significant differences;The hospital fasting plasma glucose and LDL-C level of two groups had significant differences;the treatment time after onset and infarction area of two groups had significant differences;The multi-factor Logistic regression analysis showed that atrial fibrillation, blood glucose on admission, LDL-C and large area of infarction are the factors affecting the risk of bleeding in patients with acute cerebral infarction transformation.Conclusion:Atrial fibrillation, blood glucose on admission, LDL-C, treatment time after onset and large area of infarction belongs to the patients with acute cerebral infarction after the thrombolysis transformation of bleeding risk factors.
基金supported by the Zhejiang Provincial Natural Science Foundation of China (No.Y2100430)the Zhejiang Provincial Education and Research Foundation of China (No. Y201019154)
文摘To compare the early effects of hypertonic and isotonic saline resuscitation on heme oxygenase-1 (HO-1) expression in organs of rats with hemorrhagic shock. Rats were randomly divided into hypertonic saline resuscitation (HTS), normal saline resuscitation (NS) and sham groups. HO-1 mRNA, protein expression and apoptosis were evaluated in organs. In the HTS group, significant difference was noted in HO-1 protein in small intestinal mucosa and liver compared with the NS and sham groups, and in HO-1 mRNA in liver and kidney compared with the sham group. The apoptosis of small intestinal mucosa, liver, heart, and lung was significantly lower in the HTS group than that in the NS group. In this study, small volume resuscitation with HTS can efficiently up-regulate the expression level of HO-1 in small intestinal mucosa and liver, which may be one of the mechanisms alleviating organ damage.
文摘The observations of in-situ spacecraft mission in the magnetosheath and a region of thermalized subsonic plasma behind the bow shock reveal a non-linear behaviour of plasma waves. The study of waves and optics in Physics has given the understanding of the effect of many waves coming together to form a wave field or wave packet. The common aspect of such study shows that two or more waves can superimpose constructively or destructively. The sudden high magnetic field data in the magnetosheath displays such possibility of superposition of waves. In this paper, we use the empirical mode decomposition (EMD) and Hilbert transform (HT) techniques to determine the instantaneous frequencies of low frequency plasma waves in the magnetosheath. Our analysis has shown that the turbulent behavior of magnetic field in the magnetosheath within the selected period is due to superposition of waves.
文摘With the improvement of high temperature superconductor (HTS) practical performance, research and development concerning the applications of HTS transformers have been progressed actively worldwide. This paper provides a comprehensive summary on various HTS transformers, and studies the design of a single-phase 10 kVA (220V/24V) HTS transformer prototype to verify HTS for practical transformer applications.
文摘目的分析亚甲基四氢叶酸还原酶(MTHFR)基因多态性对脑梗死患者阿替普酶静脉溶栓后出血性转化(HT)的影响。方法回顾性分析2020年7月—2023年7月在安徽医科大学附属阜阳人民医院接受治疗的120例脑梗死患者的临床资料。依据治疗后24~72 h HT发生情况分为HT组(15例)、无HT组(105例)。比较两组基线资料、MTHFR基因多态性、纤维蛋白原(Fib)、同型半胱氨酸(Hcy)。采用多因素一般Logistic回归模型分析脑梗死患者阿替普酶静脉溶栓后HT发生的危险因素。绘制受试者工作特征(ROC)曲线,分析入院时美国国立卫生院卒中量表(NIHSS)评分、Hcy预测脑梗死患者阿替普酶静脉溶栓后HT发生的价值。结果HT组心房颤动发生率、MTHFR基因型677CT占比、入院时NIHSS评分、Hcy水平均高于无HT组(P<0.05)。多因素一般Logistic回归分析结果显示:心房颤动史[OR=1.478(95%CI:1.126,1.940)]、入院时NIHSS评分升高[OR=1.656(95%CI:1.125,2.438)]、MTHFR基因型为677CT[OR=1.871/2.362(95%CI:1.052,3.328/1.081,4.652)]、Hcy水平升高[OR=2.149(95%CI:1.108,4.168)]均为脑梗死患者阿替普酶静脉溶栓后HT发生的危险因素(P<0.05)。ROC曲线分析结果显示,入院时NIHSS评分、Hcy均可预测脑梗死患者阿替普酶静脉溶栓后HT发生,其敏感性分别为80.0%(95%CI:0.765,0.883)、73.3%(95%CI:0.717,0.834),特异性分别为74.3%(95%CI:0.659,0.817)、74.3%(95%CI:0.824,0.931)。677CT型患者Hcy水平高于677CC、677TT型患者(P<0.05)。结论心房颤动、MTHFR基因型、入院时NIHSS评分、Hcy均为影响脑梗死患者阿替普酶静脉溶栓后HT发生的重要因素,临床应结合以上指标对高危患者进行重点筛查,尽早采取干预措施。