A 56- year-old man complained of headache and the analgesia of the four extremities. Laboratory data presented signs of inflammation, but no other abnormality such as renal or respiratory dysfunction. Two months after...A 56- year-old man complained of headache and the analgesia of the four extremities. Laboratory data presented signs of inflammation, but no other abnormality such as renal or respiratory dysfunction. Two months after the appearance of the primary symptoms, he developed cerebral infarction of the bilateral corona radiata. The patient did not have any of the risk factors for cerebrovascular disease. He was diagnosed with anti-neutrophil cytoplasmic autoantibody (ANCA)associated vasculitis (AAV) because the systemic examinations revealed only that he tested positive for anti-neutrophil cytoplasmic autoantibody (ANCA). Moreover, the biopsy of the sural nerve displayed microscopic polyangitis (MPA). Despite undergoing steroid pulse therapy, the patient died from the fatal cerebral hemorrhage. The clinical course of AAV is rapid progressive. In cases of atypical cerebrovascular disease, the possibility of ANCA should be investigated.展开更多
Objective: To study the effects of segmental scleral bucklingwithout encircling procedures on retrobulbar hemodynamic conditions using color Doppler imaging. Methods: In 65 consecutive eyes of 65 patients with unilate...Objective: To study the effects of segmental scleral bucklingwithout encircling procedures on retrobulbar hemodynamic conditions using color Doppler imaging. Methods: In 65 consecutive eyes of 65 patients with unilateral rhegmatogenous retinal detachment repaired by scleral buckling, we prospectively measured the blood flow velocities in the ophthalmic artery, central retinal artery, and short posterior ciliary artery using color Doppler imaging before and 2, 12, and 24 weeks after surgery. Peak systolic velocity (PSV) and end diastolic velocity (EDV) (calculated in centimeters per second) were measured using color Doppler imaging. Results: The PSV and EDV in the ophthalmic artery were not changed significantly during follow-up. The PSV and EDV in the central retinal artery were reduced temporarily at 2 weeks after surgery, but at 12 weeks after surgery had returned to presurgery levels. The PSV and EDV in the short posterior ciliary artery on both sides continued to decrease postoperatively, and the reductions became statistically significant by 24weeks after surgery (buckled side: P=.001 for PSV and P=.002 for EDV; unbuckled side: P< .001 for PSV and P=.004 for EDV). The decreases of PSV and EDV in the short posterior ciliary artery on the buckled side were positively correlated with the subject’s age (R=0.40, P=.001 for PSV; and R=0.32, P=.008 for EDV). Conclusions: Scleral buckling procedures can cause subclinical disturbance of the choroidal circulation, even if encircling procedures are avoided. Aging is one of the risk factors for the disturbance.展开更多
氢可以从各种再生能源中产生,因此预计,氢将会在社会长期能源需求中起到重要作用。传统氢发动机存在的一些缺点是:冷却损失较高导致热效率较低,以及不正常燃烧(回火、早燃、燃烧速度较快)限制了大负荷运行。氢燃料直接喷射是克服这些缺...氢可以从各种再生能源中产生,因此预计,氢将会在社会长期能源需求中起到重要作用。传统氢发动机存在的一些缺点是:冷却损失较高导致热效率较低,以及不正常燃烧(回火、早燃、燃烧速度较快)限制了大负荷运行。氢燃料直接喷射是克服这些缺点的一种有效办法,但是要实现高效率和低氮氧化物(NOx)排放的燃烧方法还需要进行更详细的研究。采用一种试验性氢高压喷射器(最大喷射压力30 MPa)对高效率和低NOx排放的氢燃烧进行了研究。采用1台2.2 L 4缸涡流形燃烧室柴油机进行试验,氢喷射器安装在气缸中心,火花塞安装在预热塞位置。为了能向1个气缸提供氢气,对这台发动机进行了改装。通过控制喷油定时和点火定时研究了氢气的均相和分层燃烧。另外,还研究了联合使用火花点火的扩散燃烧(即火花点燃辅助扩散燃烧)。结果显示,采用高压直喷的分层扩散燃烧与传统的均相燃烧相比,指示热效率提高了约3%。热效率提高的原因是:(1)分层扩散燃烧改善了冷却损失与等容度之间的折衷关系;(2)接近上止点喷射的压力恢复效应十分有利于热效率的提高;(3)在废气再循环(EGR)与扩散燃烧相结合的情况下,能使EGR更为有效。通过抑制喷束的贯穿度以减少较多的冷却损失,使这台小型发动机达到了52%的优良指示热效率,并通过计算流体动力学和可视化缸内燃烧研究得到了证实。另外,还获得了一些有价值的认识:EGR除湿能增加工作气体的比热比,并能在降低NOx的同时提高热效率。展开更多
文摘A 56- year-old man complained of headache and the analgesia of the four extremities. Laboratory data presented signs of inflammation, but no other abnormality such as renal or respiratory dysfunction. Two months after the appearance of the primary symptoms, he developed cerebral infarction of the bilateral corona radiata. The patient did not have any of the risk factors for cerebrovascular disease. He was diagnosed with anti-neutrophil cytoplasmic autoantibody (ANCA)associated vasculitis (AAV) because the systemic examinations revealed only that he tested positive for anti-neutrophil cytoplasmic autoantibody (ANCA). Moreover, the biopsy of the sural nerve displayed microscopic polyangitis (MPA). Despite undergoing steroid pulse therapy, the patient died from the fatal cerebral hemorrhage. The clinical course of AAV is rapid progressive. In cases of atypical cerebrovascular disease, the possibility of ANCA should be investigated.
文摘Objective: To study the effects of segmental scleral bucklingwithout encircling procedures on retrobulbar hemodynamic conditions using color Doppler imaging. Methods: In 65 consecutive eyes of 65 patients with unilateral rhegmatogenous retinal detachment repaired by scleral buckling, we prospectively measured the blood flow velocities in the ophthalmic artery, central retinal artery, and short posterior ciliary artery using color Doppler imaging before and 2, 12, and 24 weeks after surgery. Peak systolic velocity (PSV) and end diastolic velocity (EDV) (calculated in centimeters per second) were measured using color Doppler imaging. Results: The PSV and EDV in the ophthalmic artery were not changed significantly during follow-up. The PSV and EDV in the central retinal artery were reduced temporarily at 2 weeks after surgery, but at 12 weeks after surgery had returned to presurgery levels. The PSV and EDV in the short posterior ciliary artery on both sides continued to decrease postoperatively, and the reductions became statistically significant by 24weeks after surgery (buckled side: P=.001 for PSV and P=.002 for EDV; unbuckled side: P< .001 for PSV and P=.004 for EDV). The decreases of PSV and EDV in the short posterior ciliary artery on the buckled side were positively correlated with the subject’s age (R=0.40, P=.001 for PSV; and R=0.32, P=.008 for EDV). Conclusions: Scleral buckling procedures can cause subclinical disturbance of the choroidal circulation, even if encircling procedures are avoided. Aging is one of the risk factors for the disturbance.
文摘氢可以从各种再生能源中产生,因此预计,氢将会在社会长期能源需求中起到重要作用。传统氢发动机存在的一些缺点是:冷却损失较高导致热效率较低,以及不正常燃烧(回火、早燃、燃烧速度较快)限制了大负荷运行。氢燃料直接喷射是克服这些缺点的一种有效办法,但是要实现高效率和低氮氧化物(NOx)排放的燃烧方法还需要进行更详细的研究。采用一种试验性氢高压喷射器(最大喷射压力30 MPa)对高效率和低NOx排放的氢燃烧进行了研究。采用1台2.2 L 4缸涡流形燃烧室柴油机进行试验,氢喷射器安装在气缸中心,火花塞安装在预热塞位置。为了能向1个气缸提供氢气,对这台发动机进行了改装。通过控制喷油定时和点火定时研究了氢气的均相和分层燃烧。另外,还研究了联合使用火花点火的扩散燃烧(即火花点燃辅助扩散燃烧)。结果显示,采用高压直喷的分层扩散燃烧与传统的均相燃烧相比,指示热效率提高了约3%。热效率提高的原因是:(1)分层扩散燃烧改善了冷却损失与等容度之间的折衷关系;(2)接近上止点喷射的压力恢复效应十分有利于热效率的提高;(3)在废气再循环(EGR)与扩散燃烧相结合的情况下,能使EGR更为有效。通过抑制喷束的贯穿度以减少较多的冷却损失,使这台小型发动机达到了52%的优良指示热效率,并通过计算流体动力学和可视化缸内燃烧研究得到了证实。另外,还获得了一些有价值的认识:EGR除湿能增加工作气体的比热比,并能在降低NOx的同时提高热效率。
