An improved analysis of SRPT scheduling algorithm on the basis of functional optimization

The competitive performance of the SRPT scheduling algorithm has been open for a long time except for being 2-competitive, where the objective is to minimize the total completion time. Chung et al. proved that the SRPT algorithm is 1.857-competitive. In this paper we improve their analysis and show a 1.792-competitiveness. We clearly mention that our result is not the best so far, since Sitters recently proved the algorithm is 1.250-competitive. Nevertheless, it is still well worth reporting our analytical method; our analysis is based on the modern functional optimization, which can scarcely be found in the literature on the analysis of algorithms. Our aim is to illustrate the potentiality of functional optimization with a concrete application. (C) 2012 Elsevier B.V. All rights reserved.ArticleINFORMATION PROCESSING LETTERS. 112(23): 911-915 (2012)journal articl

Average-case competitive analyses for one-way trading

Consider a trader who exchanges one dollar into yen and assume that the exchange rate fluctuates within the interval [m, M]. The game ends without advance notice, then the trader is forced to exchange all the remaining dollars at the minimum rate m. El-Yaniv et al. presented the optimal worst-case threat-based strategy for this game (El-Yaniv et al. 2001). In this paper, under the assumption that the distribution of the maximum exchange rate is known, we provide average-case analyses using all the reasonable optimization measures and derive different optimal strategies for each of them. Remarkable differences in behavior are as follows: Unlike other strategies, the average-case threat-based strategy that minimizes E[OPT/ALG] exchanges little by little. The maximization of E[ALG/OPT] and the minimization of E[OPT]/E[ALG] lead to similar strategies in that both exchange all at once. However, their timing is different. We also prove minimax theorems with respect to each objective function.ArticleJOURNAL OF COMBINATORIAL OPTIMIZATION. 21(1): 83-107 (2011)journal articl

An Improved Analysis of SRPT Scheduling Algorithm on the Basis of Functional Optimization *

Abstract The competitive performance of the SRPT scheduling algorithm has been open for a long time except for being 2-competitive, where the objective is to minimize the total completion time. Chung et al. proved that the SRPT algorithm is 1.857-competitive. In this paper we improve their analysis and show a 1.792-competitiveness. We clearly mention that our result is not the best so far, since Sitters recently proved the algorithm is 1.250-competitive. Nevertheless, it is still well worth reporting our analytical method; our analysis is based on the modern functional optimization, which can scarcely be found in the literature on the analysis of algorithms. Our aim is to illustrate the potentiality of functional optimization with a concrete application

Spectrum of Disorders Associated with Elevated Serum IgG4 Levels Encountered in Clinical Practice

IgG4-related disease (IgG4-RD) is a recently described systemic fibroinflammatory disease associated with elevated circulating levels of IgG4 and manifests a wide spectrum of clinical presentations. Although serum IgG4 level has been described to be the most sensitive and specific laboratory test for the diagnosis of IgG4-RD, it is recognized that an elevated serum IgG4 level can be encountered in other diseases. In this study, we sought to identify the frequency of IgG4-RD and other disease associations in patients with elevated serum IgG4 levels seen in clinical practice. Among 3,300 patients who underwent IgG subclass testing over a 2-year period from January 2009 to December 2010, 158 (4.8%) had an elevated serum IgG4 level (>140 mg/dL). IgG4 subclass testing was performed for evaluation of suspected IgG4-RD or immunodeficiency. Twenty-nine patients (18.4%) had definite or possible IgG4-RD. Among those patients without IgG4-RD, a broad spectrum of biliary tract, pancreatic, liver, and lung diseases, as well as systemic vasculitis, was diagnosed. We conclude that patients with elevated serum IgG4 levels encountered in clinical practice manifest a wide array of disorders, and only a small minority of them has IgG4-RD

Mammalian enzymes for preventing transcriptional errors caused by oxidative damage

8-Oxo-7,8-dihydroguanine (8-oxoGua) is produced in cells by reactive oxygen species normally formed during cellular metabolic processes. This oxidized base can pair with both adenine and cytosine, and thus the existence of this base in messenger RNA would cause translational errors. The MutT protein of Escherichia coli degrades 8-oxoGua-containing ribonucleoside di- and triphosphates to the monophosphate, thereby preventing the misincorporation of 8-oxoGua into RNA. Here, we show that for human the MutT-related proteins, NUDT5 and MTH1 have the ability to prevent translational errors caused by oxidative damage. The increase in the production of erroneous proteins by oxidative damage is 28-fold over the wild-type cells in E.coli mutT deficient cells. By the expression of NUDT5 or MTH1 in the cells, it is reduced to 1.4- or 1.2-fold, respectively. NUDT5 and MTH1 hydrolyze 8-oxoGDP to 8-oxoGMP with V(max)/K(m) values of 1.3 × 10(−3) and 1.7 × 10(−3), respectively, values which are considerably higher than those for its normal counterpart, GDP (0.1–0.5 × 10(−3)). MTH1, but not NUDT5, possesses an additional activity to degrade 8-oxoGTP to the monophosphate. These results indicate that the elimination of 8-oxoGua-containing ribonucleotides from the precursor pool is important to ensure accurate protein synthesis and that both NUDT5 and MTH1 are involved in this process in human cells

When to incorporate point-of-care ultrasound (POCUS) into the initial assessment of acutely ill patients: a pilot crossover study to compare 2 POCUS-assisted simulation protocols.

BACKGROUND: The purpose of this study was to determine the ideal timing for providers to perform point-of-care ultrasound (POCUS) with the least increase in workload. METHODS: We conducted a pilot crossover study to compare 2 POCUS-assisted evaluation protocols for acutely ill patients: sequential (physical examination followed by POCUS) vs parallel (POCUS at the time of physical examination). Participants were randomly assigned to 2 groups according to which POCUS-assisted protocol (sequential vs parallel) was used during simulated scenarios. Subsequently, the groups were crossed over to complete assessment by using the other POCUS-assisted protocol in the same patient scenarios. Providers\u27 workloads, measured with the National Aeronautics and Space Administration Task Load Index (NASA-TLX) and time to complete patient evaluation, were compared between the 2 protocols. RESULTS: Seven providers completed 14 assessments (7 sequential and 7 parallel). The median (IQR) total NASA-TLX score was 30 (30-50) in the sequential and 55 (50-65) in the parallel protocol (P = .03), which suggests a significantly lower workload in the sequential protocol. When individual components of the NASA-TLX score were evaluated, mental demand and frustration level were significantly lower in the sequential than in the parallel protocol (40 [IQR, 30-60] vs 50 [IQR, 40-70]; P = .03 and 25 [IQR, 20-35] vs 60 [IQR, 45-85]; P = .02, respectively). The time needed to complete the assessment was similar between the sequential and parallel protocols (8.7 [IQR, 6-9] minutes vs 10.1 [IQR, 7-11] minutes, respectively; P = .30). CONCLUSIONS: A sequential POCUS-assisted protocol posed less workload to POCUS operators than the parallel protocol