Phase Change Memory (PCM) is a promising technology for building future main memory systems. A prominent characteristic of PCM is that it has write latency much higher than read latency. Servicing such slow writes causes significant contention for read requests. For our baseline PCM system, the slow writes increase the effective read latency by almost 2X, causing significant performance degradation.This paper alleviates the problem of slow writes by exploiting the fundamental property of PCM devices that writes are slow only in one direction (SET operation) and are almost as fast as reads in the other direction (RESET operation). Therefore, a write operation to a line in which all memory cells have been SET prior to the write, will incur much lower latency. We propose PreSET, an architectural technique that leverages this property to pro-actively SET all the bits in a given memory line well in advance of the anticipated write to that memory line. Our proposed design initiates a PreSET request for a memory line as soon as that line becomes dirty in the cache, thereby allowing a large window of time for the PreSET operation to complete. Our evaluations show that PreSET is more effective and incurs lower storage overhead than previously proposed write cancellation techniques. We also describe static and dynamic throttling schemes to limit the rate of PreSET operations. Our proposal reduces effective read latency from 982 cycles to 594 cycles and increases system performance by 34%, while improving the energy-delay-product by 25%.
1. The pharmacokinetics of pefloxacin and its active metabolite norfloxacin were investigated in chickens after a single oral administration of pefloxacin at a dosage of 10 mg/kg. To characterise the residue pattern, another group of chickens was given 10 mg of pefloxacin/kg body once daily for 4 d by oral route; the tissue concentrations of pefloxacin and norfloxacin were determined at 1, 5 and 10 d after the last administration of the drug. 2. The concentrations of pefloxacin and norfloxacin in plasma and tissues were determined by HPLC assay. The limit of detection for pefloxacin and norfloxacin was 0.03 microg/ml in plasma or microg/g in tissue. 3. The plasma concentration-time data for pefloxacin and norfloxacin were characteristic of a one-compartment open model. The elimination half-life, maximum plasma drug concentration, time to reach maximum plasma drug concentration and mean residence time of pefloxacin were 8.74 +/- 1.48 h, 3.78 +/- 0.23 microg/ml, 3.33 +/- 0.21 h and 14.32 +/- 1.94 h, respectively, whereas the respective values of these variables for norfloxacin were 5.66 +/- 0.81 h, 0.80 +/- 0.07 microg/ml, 3.67 +/- 0.21 h and 14.44 +/- 0.97 h. 4. Pefloxacin was metabolised to norfloxacin to the extent of 22%. 5. The concentrations of pefloxacin (microg/g) 24 h after the fourth dose of the drug declined in the following order: liver (3.20 +/- 0.40) > muscle (1.42 +/- 0.18) > kidney (0.69 +/- 0.04) > skin and fat (0.06 +/- 0.02). Norfloxacin was also detectable in all the tissues analysed except muscle. No drug and/or its metabolite was detectable in tissues except skin and fat 5 d after the last administration. The concentrations of pefloxacin and norfloxacin in skin and fat 10 d after the last dose of pefloxacin were 0.04 +/- 0.02 and 0.03 +/- 0.01 microg/g, respectively.
Objective:We present our experience with transperineal bulboprostatic anastomosis procedure and compare the results with age of patients, length of urethral stricture, effect of previous treatment and need for ancillary procedures.Materials and Methods:We retrospectively reviewed the outcome of 172 patients who underwent perineal urethroplasty procedure for traumatic stricture in our institute. Simple perineal anastomosis was done in 92 patients. Perineal anastomosis and corporal separation were done in 52 patients. Perineal anastomosis with inferior pubectomy was done in 25 patients. Perineal anastomosis with rerouting was done in three patients. Age, prior treatment, length of stricture, and ancillary techniques required during reconstruction were compiled. The clinical outcome was considered as failure when any postoperative instrumentation was needed.Results:Out of 172 cases that underwent transperineal urethroplasty procedure, 157 (91.28%) were successful. Simple perineal urethroplasty procedure showed a success rate of 93.4%, perineal anastomosis with separation of corporal bodies had a success rate of 90.4%, perineal anastomosis with inferior pubectomy had a success rate of 88% and perineal anastomosis with rerouting of urethra around the corpora had a success rate of 66.7%.Conclusion:The success rate of delayed progressive perineal urethroplasty procedure for post-traumatic stricture urethra is excellent and majority of the failures occurs in prepubescent boys and in those undergoing secondary repair.
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