No abstract

BackgroundIntravenous recombinant tissue plasminogen activator (r-tPA) and urokinase (UK) are both recommended for the treatment of acute ischaemic stroke (AIS) in China, but with few comparative outcome data being available. We aimed to compare the outcomes of these two thrombolytic agents for the treatment of patients within 4.5 hours of onset of AIS in routine clinical practice in China.MethodsA pre-planned, prospective, nationwide, multicentre, real-world registry of consecutive patients with AIS (age ≥18 years) who received r-tPA or UK within 4.5 hours of symptom onset according to local decision-making and guideline recommendations during 2017–2019. The primary effectiveness outcome was the proportion of patients with an excellent functional outcome (defined by modified Rankin scale scores 0 to 1) at 90 days. The key safety endpoint was symptomatic intracranial haemorrhage according to standard definitions. Multivariable logistic regression was used for comparative analysis, with adjustment according to propensity scores to ensure balance in baseline characteristics.ResultsOverall, 4130 patients with AIS were registered but 320 had incomplete or missing data, leaving 3810 with available data for analysis of whom 2666 received r-tPA (median dose 0.88 (IQR 0.78–0.90) mg/kg) and 1144 received UK (1.71 (1.43–2.00)×104 international unit per kilogram). There were several significant intergroup differences in patient characteristics: r-tPA patients were more educated, had less history of stroke, lower systolic blood pressure, greater neurological impairment and shorter treatment times from symptom onset than UK patients. However, in adjusted analysis, the frequency of excellent outcome (OR 1.18, 95% CI 1.00 to 1.40, p=0.052) and symptomatic intracranial haemorrhage (OR 0.70, 95% CI 0.33 to 1.47, p=0.344) were similar between groups.ConclusionsUK may be as effective and carry a similar safety profile as r-tPA in treating mild to moderate AIS within guidelines in China.Registrationhttp://www.clinicaltrials.gov. unique identifier: NCT02854592.

The current parallel storage systems use thousands of inexpensive disks to meet the storage requirement of applications. Data redundancy and/or coding are used to enhance data availability, for instance, Rowdiagonal parity (RDP) and EVENODD codes, which are widely used in RAID-6 storage systems, provide data availability with up to two disk failures. To reduce the probability of data unavailability, whenever a single disk fails, disk recovery will be carried out. We find that the conventional recovery schemes of RDP and EVENODD codes for a single failed disk only use one parity disk. However, there are two parity disks in the system, and both can be used for single disk failure recovery. In this article, we propose a hybrid recovery approach that uses both parities for single disk failure recovery, and we design efficient recovery schemes for RDP code (RDOR-RDP) and EVENODD code (RDOR-EVENODD). Our recovery scheme has the following attractive properties: (1) "read optimality" in the sense that our scheme issues the smallest number of disk reads to recover a single failed disk and it reduces approximately 1/4 of disk reads compared with conventional schemes; (2) "load balancing property" in that all surviving disks will be subjected to the same (or almost the same) amount of additional workload in rebuilding the failed disk.We carry out performance evaluation to quantify the merits of RDOR-RDP and RDOR-EVENODD on some widely used disks with DiskSim. The offline experimental results show that RDOR-RDP and RDOR-EVENODD outperform the conventional recovery schemes of RDP and EVENODD codes in terms of total recovery time and recovery workload on individual surviving disk. However, the improvements are less than the theoretical value (approximately 25%), as RDOR-RDP and RDOR-EVENODD change the disk access pattern from purely sequential to a more random one compared with their conventional schemes.

This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Data availability is critical in distributed storage systems, especially when node failures are prevalent in real life. A key requirement is to minimize the amount of data transferred among nodes when recovering the lost or unavailable data of failed nodes. This paper explores recovery solutions based on regenerating codes, which are shown to provide fault-tolerant storage and minimum recovery bandwidth. Existing optimal regenerating codes are designed for single node failures. We build a system called CORE, which augments existing optimal regenerating codes to support a general number of failures including single and concurrent failures. We theoretically show that CORE achieves the minimum possible recovery bandwidth for most cases. We implement CORE and evaluate our prototype atop a Hadoop HDFS cluster testbed with up to 20 storage nodes. We demonstrate that our CORE prototype conforms to our theoretical findings and achieves recovery bandwidth saving when compared to the conventional recovery approach based on erasure codes.