32 research outputs found
Optimal deployment of components of cloud-hosted application for guaranteeing multitenancy isolation
One of the challenges of deploying multitenant cloud-hosted
services that are designed to use (or be integrated with) several
components is how to implement the required degree
of isolation between the components when there is a change
in the workload. Achieving the highest degree of isolation
implies deploying a component exclusively for one tenant;
which leads to high resource consumption and running cost
per component. A low degree of isolation allows sharing of
resources which could possibly reduce cost, but with known
limitations of performance and security interference. This
paper presents a model-based algorithm together with four
variants of a metaheuristic that can be used with it, to provide
near-optimal solutions for deploying components of a
cloud-hosted application in a way that guarantees multitenancy
isolation. When the workload changes, the model based
algorithm solves an open multiclass QN model to
determine the average number of requests that can access
the components and then uses a metaheuristic to provide
near-optimal solutions for deploying the components. Performance
evaluation showed that the obtained solutions had
low variability and percent deviation when compared to the
reference/optimal solution. We also provide recommendations
and best practice guidelines for deploying components
in a way that guarantees the required degree of isolation
Validated spectrofluorimetric method for the determination of tamsulosin in spiked human urine, pure and pharmaceutical preparations
A novel, sensitive and selective spectrofluorimetric method was developed for the determination of tamsulosin in spiked human urine and pharmaceutical preparations. The proposed method is based on the reaction of tamsulosin with 1-dimethylaminonaphthalene-5-sulfonyl chloride in carbonate buffer pH10.5 to yield a highly fluorescent derivative. The described method was validated and the analytical parameters of linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, recovery and robustness were evaluated. The proposed method showed a linear dependence of the fluorescence intensity on drug concentration over the range 1.22 x 10(-7) to 7.35 x 10(-6)M. LOD and LOQ were calculated as 1.07 x 10(-7) and 3.23 x 10(-7)M, respectively. The proposed method was successfully applied for the determination of tamsulosin in pharmaceutical preparations and the obtained results were in good agreement with those obtained using the reference method. Copyright (c) 2013 John Wiley & Sons, Ltd
Spectrofluorimetric determination of famciclovir in pure and pharmaceutical preparations
A sensitive spectrofluorimetric method was developed for the determination of famciclovir in pure and pharmaceutical preparations. The method is based on the derivatization reaction of famciclovir with fluorescamine. The different experimental parameters that affect the fluorescence intensity were carefully studied, at once. The method was validated for linearity, limit of detection, limit of quantification, precision, accuracy, recovery, robustness. The assay was linear over the concentration range of 100 and 1000 ng/mL. The limits of detection and limit of quantification were calculated to be 51.13 and 153.39 ng/mL. The proposed method was applied to study of famciclovir in pure and in pharmaceutical preparations
New spectrofluorimetric method for the determination of nizatidine in bulk form and in pharmaceutical preparations
A simple, accurate and highly sensitive spectrofluorimetric method has been developed for determination of nizatidine in pure form and in pharmaceutical dosage forms. The method is based on the reaction between nizatidine and 1-dimethylaminonaphthalene-5-sulphonyl chloride in carbonate buffer, pH 10.5, to yield a highly fluorescent derivative peaking at 513 nm after excitation at 367 nm. Various factors affecting the fluorescence intensity of nizatidin-dansyl derivative were studied and conditions were optimized. The method was validated as per ICH guidelines. The fluorescence concentration plot was rectilinear over the range of 25-300 ng/mL. Limit of detection and limit of quantification were calculated as 11.71 and 35.73 ng/mL, respectively. The proposed method was successfully applied to pharmaceutical preparations