BACKGROUND： Due to collateral circulation and cerebrovascular reserve, arterial stenosis and reduced cerebral blood flow may not necessarily indicate impaired cerebral peffusion. Therefore, according to degree of ste...BACKGROUND： Due to collateral circulation and cerebrovascular reserve, arterial stenosis and reduced cerebral blood flow may not necessarily indicate impaired cerebral peffusion. Therefore, according to degree of stenosis and clinical symptoms, interventional surgery to relieve arterial stenosis in transient ischemic attack （TIA） patients with major intracranial stenosis is imprudent. Rather, cerebral perfusion and reserve capacity are direct indicators for the assessment of degree and presence of cerebral ischemia. OBJECTIVE： To evaluate cerebral perfusion and reserve in TIA patients with major intracranial stenosis or occlusion using magnetic resonance-perfusion-weighted imaging （MR-PWl） data prior to and following diamox administration. DESIGN, TIME AND SETTING： A self-comparative, neuroimaging observation was performed at the Neurological Department and Radiological Center of the First Affiliated Hospital of Jinan University between December 2007 and April 2009. PARTICIPANTS： Seven acute TIA patients, who were admitted to the Neurological Department of the First Affiliated Hospital of Jinan University between December 2007 and April 2009, were enrolled in the present study. Magnetic resonance imaging confirmed that no acute cerebral infarction happened, nor did bleeding exist. Magnetic resonance angiography, transcranial Doppler ultrasound, and/or digital subtraction angiography confirmed the presence of major intracranial arterial stenosis. Clinical symptoms corresponded to blood supplying regions of the arterial stenosis. METHODS： Baseline MR-PWI was performed on seven patients with intracranial stenosis or occlusion. Two grams of acetazolamide （diamox） were orally administered after 2 days. A second PWl was performed after 2 hours to compare cerebral perfusion parameters prior to and following diamox administration. MAIN OUTCOME MEASURES： PWI results of cerebral perfusion prior to and following diamox administration. RESULTS： The baseline PWl from five patients indicated decreased cerebral perfusion areas. Following oral administration of diamox, cerebral perfusion significantly decreased in those areas. Moreover, new areas of decreased cerebral perfusion were observed in two out of the five patients. In one patient, no significant decrease in cerebral perfusion was found. In another patient, baseline PWl indicated decreased cerebral perfusion in the left hemisphere. However, normal perfusion was observed in both cerebral lobes following diamox administration. CONCLUSION： TIA patients with intracranial stenosis, who are diagnosed by PWI and exhibited decreased cerebral perfusion and reserve, might require further treatment such as intervention by angioptasty.展开更多
联邦学习作为一种分布式机器学习框架,能够在数据隔离和隐私保护的前提下实现多方协作训练,但其分布式特性使其容易成为后门攻击的目标.提出基于约束扰动与损失调控(constrained perturbation and loss regulation,CPR)的联邦学习后门...联邦学习作为一种分布式机器学习框架,能够在数据隔离和隐私保护的前提下实现多方协作训练,但其分布式特性使其容易成为后门攻击的目标.提出基于约束扰动与损失调控(constrained perturbation and loss regulation,CPR)的联邦学习后门攻击方法.该方法通过输入扰动、动态权重调控、2次扰动强化3个模块,实现了后门的植入与扩散.输入扰动通过对样本添加约束噪声毒化样本.动态权重调控通过引入余弦退火动态调整任务权重,实现了后门特性学习与主任务性能的平衡.2次扰动强化利用动态损失值进一步对毒化样本进行扰动,强化其后门特征.在MNIST,Fashion-MNIST,CIFAR10数据集上对CPR后门攻击进行评估,实验结果表明,与像素攻击、标签翻转攻击和混合攻击相比,CPR后门攻击在维持模型主任务准确率的同时,能够显著提高攻击成功率,并在多种数据分布条件下表现出更高的隐蔽性和持久性.展开更多
This paper presents an improved simple power attack against the key schedule of Camellia. While the original attack required an exact determination of the Hamming weight of intermediate data values based on power meas...This paper presents an improved simple power attack against the key schedule of Camellia. While the original attack required an exact determination of the Hamming weight of intermediate data values based on power measurements, in this paper, two types of the simple power attack are presented and shown to be tolerant of errors that might occur in the Hamming weight determinations. In practical applications of the attack, such errors are likely to occur due to noise and distortion in the power measurements and their mapping to the Hamming weights of the data. To resist these attacks, the required design rationale of key schedules and several practical countermeasures are suggested.展开更多
Network attack graphs are originally used to evaluate what the worst security state is when a concerned net-work is under attack. Combined with intrusion evidence such like IDS alerts, attack graphs can be further use...Network attack graphs are originally used to evaluate what the worst security state is when a concerned net-work is under attack. Combined with intrusion evidence such like IDS alerts, attack graphs can be further used to perform security state posterior inference (i.e. inference based on observation experience). In this area, Bayesian network is an ideal mathematic tool, however it can not be directly applied for the following three reasons: 1) in a network attack graph, there may exist directed cycles which are never permitted in a Bayesian network, 2) there may exist temporal partial ordering relations among intrusion evidence that can-not be easily modeled in a Bayesian network, and 3) just one Bayesian network cannot be used to infer both the current and the future security state of a network. In this work, we improve an approximate Bayesian posterior inference algorithm–the likelihood-weighting algorithm to resolve the above obstacles. We give out all the pseudocodes of the algorithm and use several examples to demonstrate its benefit. Based on this, we further propose a network security assessment and enhancement method along with a small network scenario to exemplify its usage.展开更多
This case report investigates the manifestation of cerebral amyloid angiopathy (CAA) through recurrent Transient Ischemic Attacks (TIAs) in an 82-year-old patient. Despite initial diagnostic complexities, cerebral ang...This case report investigates the manifestation of cerebral amyloid angiopathy (CAA) through recurrent Transient Ischemic Attacks (TIAs) in an 82-year-old patient. Despite initial diagnostic complexities, cerebral angiography-MRI revealed features indicative of CAA. Symptomatic treatment resulted in improvement, but the patient later developed a fatal hematoma. The discussion navigates the intricate therapeutic landscape of repetitive TIAs in the elderly with cardiovascular risk factors, emphasizing the pivotal role of cerebral MRI and meticulous bleeding risk management. The conclusion stresses the importance of incorporating SWI sequences, specifically when suspecting a cardioembolic TIA, as a diagnostic measure to explore and exclude CAA in the differential diagnosis. This case report provides valuable insights into these challenges, highlighting the need to consider CAA in relevant cases.展开更多
配电变压器三相不平衡运行异常监测容易受到外界噪声干扰,导致监测结果出现偏差,因此提出结合虚假数据注入攻击(False Data Injection Attack,FDIA)检测模型和指数加权移动平均的异常监测方法。通过分布式FDIA检测模型,提取三相不平衡...配电变压器三相不平衡运行异常监测容易受到外界噪声干扰,导致监测结果出现偏差,因此提出结合虚假数据注入攻击(False Data Injection Attack,FDIA)检测模型和指数加权移动平均的异常监测方法。通过分布式FDIA检测模型,提取三相不平衡运行异常数据。利用指数加权移动平均方法,平滑处理误差。以滑动窗口的均值为中心,分析运行异常情况,计算三相电压不平衡度,实现三相不平衡运行异常监测。实验结果表明,该方法的监测准确性较高,为电力系统的安全稳定运行提供有力保障。展开更多
基金Medical Scientific and Technological Research Foundation of Guangdong Province, No. 2007332 2009360the Natural Science Foundation of Guangdong Province, No. 9451063201002951
文摘BACKGROUND： Due to collateral circulation and cerebrovascular reserve, arterial stenosis and reduced cerebral blood flow may not necessarily indicate impaired cerebral peffusion. Therefore, according to degree of stenosis and clinical symptoms, interventional surgery to relieve arterial stenosis in transient ischemic attack （TIA） patients with major intracranial stenosis is imprudent. Rather, cerebral perfusion and reserve capacity are direct indicators for the assessment of degree and presence of cerebral ischemia. OBJECTIVE： To evaluate cerebral perfusion and reserve in TIA patients with major intracranial stenosis or occlusion using magnetic resonance-perfusion-weighted imaging （MR-PWl） data prior to and following diamox administration. DESIGN, TIME AND SETTING： A self-comparative, neuroimaging observation was performed at the Neurological Department and Radiological Center of the First Affiliated Hospital of Jinan University between December 2007 and April 2009. PARTICIPANTS： Seven acute TIA patients, who were admitted to the Neurological Department of the First Affiliated Hospital of Jinan University between December 2007 and April 2009, were enrolled in the present study. Magnetic resonance imaging confirmed that no acute cerebral infarction happened, nor did bleeding exist. Magnetic resonance angiography, transcranial Doppler ultrasound, and/or digital subtraction angiography confirmed the presence of major intracranial arterial stenosis. Clinical symptoms corresponded to blood supplying regions of the arterial stenosis. METHODS： Baseline MR-PWI was performed on seven patients with intracranial stenosis or occlusion. Two grams of acetazolamide （diamox） were orally administered after 2 days. A second PWl was performed after 2 hours to compare cerebral perfusion parameters prior to and following diamox administration. MAIN OUTCOME MEASURES： PWI results of cerebral perfusion prior to and following diamox administration. RESULTS： The baseline PWl from five patients indicated decreased cerebral perfusion areas. Following oral administration of diamox, cerebral perfusion significantly decreased in those areas. Moreover, new areas of decreased cerebral perfusion were observed in two out of the five patients. In one patient, no significant decrease in cerebral perfusion was found. In another patient, baseline PWl indicated decreased cerebral perfusion in the left hemisphere. However, normal perfusion was observed in both cerebral lobes following diamox administration. CONCLUSION： TIA patients with intracranial stenosis, who are diagnosed by PWI and exhibited decreased cerebral perfusion and reserve, might require further treatment such as intervention by angioptasty.
文摘联邦学习作为一种分布式机器学习框架,能够在数据隔离和隐私保护的前提下实现多方协作训练,但其分布式特性使其容易成为后门攻击的目标.提出基于约束扰动与损失调控(constrained perturbation and loss regulation,CPR)的联邦学习后门攻击方法.该方法通过输入扰动、动态权重调控、2次扰动强化3个模块,实现了后门的植入与扩散.输入扰动通过对样本添加约束噪声毒化样本.动态权重调控通过引入余弦退火动态调整任务权重,实现了后门特性学习与主任务性能的平衡.2次扰动强化利用动态损失值进一步对毒化样本进行扰动,强化其后门特征.在MNIST,Fashion-MNIST,CIFAR10数据集上对CPR后门攻击进行评估,实验结果表明,与像素攻击、标签翻转攻击和混合攻击相比,CPR后门攻击在维持模型主任务准确率的同时,能够显著提高攻击成功率,并在多种数据分布条件下表现出更高的隐蔽性和持久性.
基金the National Natural Science Foundation of China (60673072)the Natural Basic Research Program of China (2007CB311201)
文摘This paper presents an improved simple power attack against the key schedule of Camellia. While the original attack required an exact determination of the Hamming weight of intermediate data values based on power measurements, in this paper, two types of the simple power attack are presented and shown to be tolerant of errors that might occur in the Hamming weight determinations. In practical applications of the attack, such errors are likely to occur due to noise and distortion in the power measurements and their mapping to the Hamming weights of the data. To resist these attacks, the required design rationale of key schedules and several practical countermeasures are suggested.
文摘Network attack graphs are originally used to evaluate what the worst security state is when a concerned net-work is under attack. Combined with intrusion evidence such like IDS alerts, attack graphs can be further used to perform security state posterior inference (i.e. inference based on observation experience). In this area, Bayesian network is an ideal mathematic tool, however it can not be directly applied for the following three reasons: 1) in a network attack graph, there may exist directed cycles which are never permitted in a Bayesian network, 2) there may exist temporal partial ordering relations among intrusion evidence that can-not be easily modeled in a Bayesian network, and 3) just one Bayesian network cannot be used to infer both the current and the future security state of a network. In this work, we improve an approximate Bayesian posterior inference algorithm–the likelihood-weighting algorithm to resolve the above obstacles. We give out all the pseudocodes of the algorithm and use several examples to demonstrate its benefit. Based on this, we further propose a network security assessment and enhancement method along with a small network scenario to exemplify its usage.
文摘This case report investigates the manifestation of cerebral amyloid angiopathy (CAA) through recurrent Transient Ischemic Attacks (TIAs) in an 82-year-old patient. Despite initial diagnostic complexities, cerebral angiography-MRI revealed features indicative of CAA. Symptomatic treatment resulted in improvement, but the patient later developed a fatal hematoma. The discussion navigates the intricate therapeutic landscape of repetitive TIAs in the elderly with cardiovascular risk factors, emphasizing the pivotal role of cerebral MRI and meticulous bleeding risk management. The conclusion stresses the importance of incorporating SWI sequences, specifically when suspecting a cardioembolic TIA, as a diagnostic measure to explore and exclude CAA in the differential diagnosis. This case report provides valuable insights into these challenges, highlighting the need to consider CAA in relevant cases.
文摘配电变压器三相不平衡运行异常监测容易受到外界噪声干扰,导致监测结果出现偏差,因此提出结合虚假数据注入攻击(False Data Injection Attack,FDIA)检测模型和指数加权移动平均的异常监测方法。通过分布式FDIA检测模型,提取三相不平衡运行异常数据。利用指数加权移动平均方法,平滑处理误差。以滑动窗口的均值为中心,分析运行异常情况,计算三相电压不平衡度,实现三相不平衡运行异常监测。实验结果表明,该方法的监测准确性较高,为电力系统的安全稳定运行提供有力保障。
