Nitroglycerin reduces augmentation index and central blood pressure independent of effects on cardiac preload

Objective To determine whether reduction In central pressure augmentation and central systolic blood pressure by nitroglycerine (NTG) results from effects on pre-lead or is due to arterial dilation. Methods We compared effects of NTG with these of lower body negative pressure (LBNP). Hemodyunmic measurements were made at rest, during LBNP (10, 20 and 30 mmHg, each for 15 min) and after NTG (10, 30 and 100μg/min, each dose for 15 min) in ten healthy volunteers. Cardiac pre-lead, stroke volume and cardiac output were assessed by echacardiography. Central pressure an mnentation and central systolic pressure were obtained by radial tonometry using a transfer function. Results LBNP (20 mmHg) and NTG (30μg/min) reduced pre-lead (as measured by the peak velocity of the S wave in the superior vena eava) to a similar degree [by (26. 8 ± 3.8) % and (23.9 ± 3. 4) %, respectively]. Compared to LBNP, NTG reduced systemic vascular resistance [by (32. 9 ± 7.5) %, p< 0. 01], decreased peripheral and central pressure augmentation [by (20. 8 ± 3. 4)% units and (12. 9±2. 9)% units, respectively, each P< 0. 01]. Conclusion These results suggest that a reduction in pre-load does not explain reduction in pressure augmentation and central systolic blood pressure by NTG and that these effects are mediated through arterial dilation.     

Connections: Bringing Florida together

During the summer of 1994 the Florida Department of Transportation hit the road seeking ideas and opinions from the state's citizens, businesses and visitors for developing a plan for Florida's future transportation system. Making a break from the past, the department decided to forego long-winded speeches, draft plans and maps too small to read in favor of more innovative approaches to public involvement. This paper details the development and implementation of the 2020 Florida Transportation Plan public outreach program, continued public involvement efforts and the lessons learned.     

Lotus Evora 破茧而出

采用了3.5L 276bhp的丰田V6引擎,2+2座椅,GT水准的抛光处理,4.5万英镑的起售价。我们有机会独家目睹Lotus令人振奋的将来。有感染力的吼叫声在Lotus的Hethel总部四周回荡。全新的Lotus Evora距离首次公开还有两个星期的时间,团队非常自信他们达成了非凡的成绩。很显然,他们丝毫没有为世人将会对这个新生"婴儿"产生一定看法而感到焦虑。     

Modeling techniques for periodic vehicle routing problems

This paper presents a continuous approximation model for the period vehicle routing problem with service choice (PVRP-SC). The PVRP-SC is a variant of the period vehicle routing problem in which the visit frequency to nodes is a decision of the model. This variation can result in more efficient vehicle tours and/or greater service benefit to customers. We present a continuous approximation model to facilitate strategic and tactical planning of periodic distribution systems and evaluate the value of service choice. Further, results from the continuous model can provide guidelines for constructing solutions to the discrete PVRP-SC.