带快照的混合数据库系统设计与应用

随着对海量数据处理的广泛需求,对数据库系统的性能也提出了更高的要求.本文介绍了一种带快照的混合数据库系统的设计.它在传统数据库系统基于磁盘存储的基础上,选择部分需被频繁或快速访问的数据以快照的形式组织在主存中,从而兼顾了处理海量数据和快速响应用户访问要求两方面的需求.最后,简要给出了一个在地理信息系统中的应用实例.     

Increased systolic daily ambulatory blood pressure in adult women born preterm

We have studied 24-h ambulatory blood pressure and kidney function in three groups of adult women: (1) born full term but with birth weights below the 3rd percentile for gestational age (n =18), (2) born preterm before gestational week 33 (median birth weight 1,250 g, range 950–2,040 g) (ex-preterm, n =14), and (3) those born full term with normal birth weights (comparison group n =17). We have previously published the results from the study. We recalculated the daily ambulatory blood pressure and redefined the time interval from 6:00–24:00 to 8:00–20:00, since this better corresponds to daily active life. We found significantly increased mean daily systolic ambulatory blood pressure in the ex-preterm group. The result supports the suggestion that disturbance and/or disruption of the normal prenatal milieu seem to affect arterial blood pressure in adult life.     

The effect of ultrasound-guided sclerotherapy of incompetent perforator veins on venous clinical severity and disability scores

PURPOSE: Current techniques to treat venous ulcerations and patients with severe lipodermatosclerosis include the elimination of incompetent perforator veins by open surgical ligation and division or by subfascial endoscopic perforator surgery. An alternative and less invasive means to obliterate perforator veins is ultrasound-guided sclerotherapy (UGS). We hypothesize that UGS is a clinically effective means of eliminating perforator veins and results in improvement of the clinical state (scores) without the complications associated with other more invasive methods. METHODS: Between January 2000 and March 2004, UGS was used to treat chronic venous insufficiency in 80 limbs of 68 patients. This was a clinical series of patients who had perforator incompetence and no previous surgery for venous disease < or = 2 years of their UGS procedure. Most had perforator disease without coexisting axial reflux of the saphenous or deep venous systems. Color flow duplex scanning was used to identify incompetent perforator veins in the calf, and duplex guidance was used to inject each perforator with the liquid sclerosant sodium morrhuate (5%). Patients were restudied by duplex scanning up to 5 years after treatment. Clinical results were determined by Venous Clinical Severity Score (VCSS) and Venous Disability Score (VDS) before and after treatment. RESULTS: Of the 80 limbs treated with UGS, 98% of incompetent perforators were successfully obliterated at the time of treatment, and 75% of limbs showed persistent occlusion of perforators and remained clinically improved with a mean follow-up of 20.1 months. According to the CEAP classification, there were 46.2% with limb ulceration or C6, 1.2% C5, 28.7% C4, 17.5% C3, and 6.2% C2 with pain isolated to the site of the perforator(s). Of those who returned for follow-up, the VCSSs changed from a median of 8 before treatment (95% confidence interval [CI], 3 to 15) to a median of 2 after treatment (95% CI, 0 to 7) (P < .01). Likewise, VDSs dropped from a median of 4 before treatment (95% CI, 1 to 3) to 1 after treatment (95% CI, 0 to 2) (P < .01). There were no cases of deep vein thrombosis involving the deep vein adjacent to the perforator injected. One patient had skin complications with skin necrosis. Perforator recurrence was found more frequently in those with ulcerations than those without. CONCLUSION: UGS is an effective and durable method of eliminating incompetent perforator veins and results in significant reduction of symptoms and signs as determined by venous clinical scores. As an alternative to open interruption or subfascial endoscopic perforator surgery, UGS may lead to fewer skin and wound healing complications. Perforator recurrence occurs particularly in those with ulcerations, and therefore, surveillance duplex scanning after UGS and repeat injections may be needed.     

Prevention of air travel-related deep venous thrombosis with mechanical devices: active foot movements produce similar hemodynamic effects

OBJECTIVE: We compared the hemodynamic effects of different mechanical devices aimed for prevention of travel-related deep venous thrombosis with active foot movements. METHODS: Two battery-operated intermittent pneumatic compression (IPC) devices and three foot and calf muscle pump facilitating devices (PFD) that claimed to prevent travel-related deep venous thrombosis were tested in 17 healthy volunteers on the ground and in 8 of same volunteers during flight. Flow changes during active foot movements were compared with the effects of each of the tested devices. RESULTS: There was no significant difference in hemodynamic effect between PFDs and active foot movements. The hemodynamic effects of IPC devices were significantly less compared with active foot movements. Values obtained during air flights were not significantly different from those obtained on the ground. CONCLUSIONS: Whereas IPC use for prevention of venous stasis during flight can be justified for immobile patients or during sleep, PFDs do not provide additional hemodynamic benefits compared with simple movements of the foot.     

全复配食用菌提取物对C26荷瘤小鼠的抑瘤作用和免疫功能影响

背景与目的:食用真菌在医疗保健领域的研究展现出强大的应用潜力.该课题探讨全复配食用菌提取物的抗肿瘤作用及对荷瘤小鼠免疫功能的影响.方法:小鼠随机编号分组,其中预防组预先给予全复配食用菌提取物灌胃2周,每天1次,之后各组均接种C26细胞建立荷瘤小鼠模型,接种后第2天给小鼠予以不同制剂灌胃(空白组灌0.9%氯化钠溶液,治疗组、预防阻灌复配食用菌提取物,CTX阳性组腹腔注射CTX)每天1次,观察记录小鼠一般状态,2周后处死小鼠无菌取脾脏、取瘤称重.MTT法检测小鼠脾淋巴细胞转化功能,乳酸脱氢酶(LDH)法检测NK细胞杀伤活性.结果:复配食用菌提取物预防组对小鼠C26肿瘤有30.4%的抑制率;小鼠脾淋巴细胞在ConA刺激下的增殖能力和NK细胞杀伤功能均显著高于空白组.结论:复配食用菌提取物预防性摄入对再接种C26小鼠有抑瘤和免疫增强作用.     

Prospective comparison of duplex scanning and descending venography in the assessment of venous insufficiency.

A prospective study comparing duplex scanning and descending venography was applied to 143 venous segments in 25 extremities with moderate to severe manifestations of chronic venous insufficiency (class 2 or 3). Duplex scanning was performed with the patient in the 15 degree reverse Trendelenburg position, and descending venography with the patient in the 60 degrees semi-erect position; the Valsalva maneuver was used to elicit reflux in both tests. The duplex parameter of reflux duration greater than 0.5 second correlated with venographic reflux in 94 of 105 segments (sensitivity of 90%). Conversely, reflux time less than or equal to 0.5 second correlated with venographic competence in 32 of 38 segments (specificity of 84%). A total of 17 discrepancies were identified among the 143 total segments studied, for an accuracy of 88%. The largest proportion of discrepancies was identified in the group with venographic competence and reflux duration greater than 0.5 second and less than or equal to 2.0 seconds; this was designated a gray zone. Mean peak velocities were significantly higher in the reflux group when compared with the competence group in the profunda femoris vein (p = 0.047), greater saphenous vein (p less than 0.001), popliteal vein (p less than 0.001), and tibial vein (p = 0.005). We conclude that venographic reflux correlates best with duplex scan findings of reflux duration greater than 0.5 second. Duration of reflux greater than 0.5 second and less than or equal to 2.0 seconds, however, represents a gray zone and should be interpreted with caution since this could lead to over-reading of reflux disease, in which case verification of incompetence by descending venography may be indicated.