Optimization based resource and cooling management for a high performance computing data center.

This paper focuses on the problem of reducing energy consumption within high-performance computing data centers, especially for those with a large portion of "small size" jobs. Different from previous works, the efficiency of job scheduling and processing is made as the first priority. To reduce energy from servers while maintaining the processing efficiency of jobs, a new hysteresis computing resource-provisioning algorithm is proposed to adjust the total computing resource reactively. A dynamical thermal model is presented to reflect the relationship between the computational system and cooling system. The proposed model is used to formulate constrained optimal control problems to minimize the energy consumption of the cooling system. Then, a two-step solution is proposed. Firstly, a thermal-aware resource allocation optimizer is developed to decide where the resource should be increased or decreased. Secondly, an economic model predictive controller is designed to adjust the cooling temperature predictively along with the variation of the rack power. Performance of the proposed method is studied through simulations with real job trace. The results show that significant energy saving can be achieved with guaranteed service quality.

A rapid, simple, specific liquid chromatographic-electrospray mass spectrometry method for the determination of finasteride in human plasma and its application to pharmacokinetic study.

A fast, accurate, sensitive, selective and reliable method using reversed-phase high-performance liquid chromatography-mass spectrometry coupling with an electrospray ionization interface was developed and validated for the determination of finasteride in human plasma. After deprotienation with acetonitrile, centrifugation, evaporation to dryness and dissolving in mobile phase, satisfactory separation was achieved on a Hypersil-Keystone C(18) reversed-phase column using a mobile phase consisting of acetonitrile-water (46:54, v/v), 0.1% acetic acid and 0.1% trifluoracetic acid. Carbamazepine (IS) was used as internal standard. This method involved the use of the [M+H](+) ions of finasteride and IS at m/z 373 and 237 with the selective ion monitoring (SIM) mode. The calibration curve was linear in the range of 0.2-120 ng ml(-1). The limit of quantification for finasteride in plasma was 0.2 ng ml(-1) with good accuracy and precision. The intra-assay precision and accuracy were in the range of 2.1-11.2% and -1.3% to 8.5%, respectively. The inter-assay precision and accuracy were in the order of 3.4-12.1% and -1.5% to 11.5%, respectively. The mean sample extract recoveries of the method were higher than 85% and 74% for finasteride and internal standard (IS), respectively. The assay has been successfully used to estimate the pharmacokinetics of finasteride after oral administration of a 5mg tablet of finasteride to 24 healthy volunteers.

Simultaneous determination of L-arginine and its mono- and dimethylated metabolites in human plasma by high-performance liquid chromatography-mass spectrometry.

A simple, fast, sensitive, and reproducible isocratic liquid chromatography-mass spectrometry (LC-MS) method coupled with an atmospheric pressure chemical ionization (APCI) interface for simultaneous separation and determination of L-arginine (ARG) and its methylated metabolites, N-monomethyl- L-arginine (MMA), NG, NG-dimethylarginine (asymmetric dimethyl arginine, ADMA), and NG, N'G-dimethylarginine (symmetric dimethyl arginine, SDMA), in human plasma is presented. Sample pretreatment is not required other than deproteinization with 5-sulfosalicylic acid (5-SSA). Satisfactory chromatographic separation was achieved on a 2.0x150-mm Shimadzu VP-ODS column by using a mobile phase consisting of water/acetonitrile (90/10, v/v) containing 0.5% trifluoroacetic acid (TFA). Positive selective ion monitoring (SIM) mode was chosen for quantification of each analyte. The positively protonated molecular ions [M+H]+ of ARG, MMA, ADMA, and SDMA were monitored at m/z 175, 189, 203, and 203, respectively. L-Homoarginine was used as the internal standard (IS) for the assay. The limits of quantification (LOQs) were found to be 1.0 micromol L(-1) for ARG, and 0.2 micromol L(-1) for MMA, ADMA, and SDMA. The inter-assay precision and accuracy were in the range of 1.8-4.9% and -3.0-5.0%, respectively. The intra-assay precision and accuracy were in the order of 1.7-4.6 and -2.6-4.0%, respectively. The recoveries were between 90.0 and 106.6%. The levels of ARG, MMA, ADMA, and SDMA in human plasma were also determined using the developed method.

Simultaneous separation and determination of active components in Cordyceps sinensis and Cordyceps militarris by LC/ESI-MS.

A simple and rapid isocratic LC/MS coupled with electrospray ionization (ESI) method for simultaneous separation and determination of adenine, hypoxanthine, adenosine and cordycepin in Cordyceps sinensis (Cs) and its substitutes was developed. 2-Chloroadenosine was used as internal standard for this assay. The optimum separation for these analytes was achieved using the mixture of water, methanol and formic acid (85:14:1, v/v/v) as a mobile phase and a 2.0 x 150 mm Shimadzu VP-ODS column. Selective ion monitoring (SIM) mode ([M+H]+ at m/z 136, 137, 268, 252 and 302) was used for quantitative analysis of above four active components. The regression equations were liner in the range of 1.4-140.0 microg ml(-1) for adenine, 0.6-117.5 microg ml(-1) for hypoxanthine, 0.5-128.5 microg ml(-1) for adenosine and 0.5-131.5 microg ml(-1) for cordycepin. The limits of quantitation (LOQ) and detection (LOD) were, respectively 1.4 and 0.5 microg ml(-1) for adenine, 0.6 and 0.2 microg ml(-1) for hypoxanthine, 0.5 and 0.1 microg ml(-1) for adenosine and cordycepin. The recoveries of four constituents were from 93.5 to 107.0%. The nucleoside contents of various types of natural Cs and its substitutes were determined and compared with this developed method.