BACKGROUND AND PURPOSE Perfusion-weighted imaging maps are used to identify hypoperfusion in acute ischemic stroke. We evaluated maps of cerebral blood flow (CBF), cerebral blood volume, mean transit time, and time to peak (TTP) in acute stroke by comparison with positron emission tomography. METHODS Perfusion-weighted imaging and positron emission tomography were performed in 26 patients wit...

In the weighted flow-time problem on a single machine, we are given a set of n jobs, where each job has a processing requirement pj , release date rj and weight wj . The goal is to find a preemptive schedule which minimizes the sum of weighted flow-time of jobs, where the flow-time of a job is the difference between its completion time and its released date. We give the first pseudo-polynomial ...

We study the parallel machine scheduling problem with release dates and we consider several “min-sum” objective functions including total weighted tardiness, total tardiness, total weighted completion time and total completion time. We describe several lower bounds for these problems, most of them being original ones. We provide experimental results to compare these lower bounds according to th...