Markovian Workload Characterization for QoS Prediction in the Cloud.

Resource allocation in the cloud is usually driven by performance predictions, such as estimates of the future incoming load to the servers or of the quality-of-service (QoS) offered by applications to end users. In this context, characterizing web workload fluctuations in an accurate way is fundamental to understand how to provision cloud resources under time-varying traffic intensities. In this paper, we investigate the Markovian Arrival Processes (MAP) and the related MAP/MAP/1 queueing model as a tool for performance prediction of servers deployed in the cloud. MAPs are a special class of Markov models used as a compact description of the time-varying characteristics of workloads. In addition, MAPs can fit heavy-tail distributions, that are common in HTTP traffic, and can be easily integrated within analytical queueing models to efficiently predict system performance without simulating. By comparison with trace-driven simulation, we observe that existing techniques for MAP parameterization from HTTP log files often lead to inaccurate performance predictions. We then define a maximum likelihood method for fitting MAP parameters based on data commonly available in Apache log files, and a new technique to cope with batch arrivals, which are notoriously difficult to model accurately. Numerical experiments demonstrate the accuracy of our approach for performance prediction of web systems. © 2011 IEEE

Development and validation of a tool to measure collaborative practice between community pharmacists and physicians from the perspective of community pharmacists: the professional collaborative practice tool.

BACKGROUND: Collaborative practice between community pharmacists and physicians is becoming increasingly common. Although tools and models to explore collaborative practice between both health care professionals have been developed, very few have been validated for their use in clinical practice. The objective of this study was to develop and validate a tool for measuring collaborative practice between community pharmacists and physicians from the perspective of community pharmacists. METHODS: The DeVellis method was used to develop and validate the Professional Collaborative Practice Tool. A pool of 40 items with Likert frequency scales was generated based on previous literature and expert opinion. This study was undertaken in Spain. A sample of community pharmacists providing medication reviews with follow-up and a random sample of pharmacists providing usual care were invited to participate. Exploratory and confirmatory factor analysis was used to assess the tool's reliability and content validity. RESULTS: Three hundred thirty-six pharmacists were invited with an overall response rate of 84.8%. The initial 40 items selected were reduced to 14 items. Exploratory Factor Analysis provided a 3-factor solution explaining 62% of the variance. Confirmatory Factor Analysis confirmed the three factors "Activation for collaborative professional practice," the "Integration in collaborative professional practice," and the "Professional acceptance in collaborative professional practice." The tool demonstrated an adequate fit (X2/df = 1.657, GFI = 0.889 and RMSEA = 0.069) and good internal consistency (Cronbach's alpha = 0.924). CONCLUSIONS: The Professional Collaborative Practice Tool has shown good internal reliability and criterion validity. The tool could be used to measure the perceived level of collaborative practice between community pharmacists and physicians and monitor changes over time. Its applicability and transferability to other settings should be evaluated

MarvelD3 regulates the c-Jun N-terminal kinase pathway during eye development in Xenopus.

Ocular morphogenesis requires several signalling pathways controlling the expression of transcription factors and cell-cycle regulators. However, despite a well-known mechanism, the dialogue between those signals and factors remains to be unveiled. Here, we identify a requirement for MarvelD3, a tight junction transmembrane protein, in eye morphogenesis in Xenopus MarvelD3 depletion led to an abnormally pigmented eye or even an eye-less phenotype, which was rescued by ectopic MarvelD3 expression. Altering MarvelD3 expression led to deregulated expression of cell-cycle regulators and transcription factors required for eye development. The eye phenotype was rescued by increased c-Jun terminal Kinase activation. Thus, MarvelD3 links tight junctions and modulation of the JNK pathway to eye morphogenesis

X-boson cumulant approach to the periodic Anderson model

The Periodic Anderson Model (PAM) can be studied in the infinite U limit by employing the Hubbard X operators to project out the unwanted states. We have already studied this problem employing the cumulant expansion with the hybridization as perturbation, but the probability conservation of the local states (completeness) is not usually satisfied when partial expansions like the Chain Approximation (CHA) are employed. Here we treat the problem by a technique inspired in the mean field approximation of Coleman's slave-bosons method, and we obtain a description that avoids the unwanted phase transition that appears in the mean-field slave-boson method both when the chemical potential is greater than the localized level Ef at low temperatures (T) and for all parameters at intermediate T.Comment: Submited to Physical Review B 14 pages, 17 eps figures inserted in the tex

Graphene-doped photo-patternable ionogels: tuning of conductivity and mechanical stability of 3D microstructures

This work reports for the first time the development of enhanced conductivity, graphene- doped photo-patternable hybrid organic-inorganic ionogels and the effect of the subsequent materials condensation on the conductivity and mechanical stability of three- dimensional microstructures fabricated by multi-photon polymerisation (MPP). Ionogels were based on photocurable silicon/zirconium hybrid sol-gel materials and phosphonium (trihexyltetradecylphosphonium dicyanamide [P6,6,6,14][DCA] ionic liquid (IL). To optimise the dispersion of graphene within the ionogel matrices, aqueous solutions of graphene were prepared, as opposed to the conventional graphene powder approach, and employed as catalysts of hydrolysis and condensation reactions occurring in the sol-gel process. Ionogels were prepared via a two step process by varying the hydrolysis degree from 25 to 50%, IL content between 0-50 w/w%, and the inorganic modifier (zirconate complex) concentration from 30 to 60 mol.% against the photocurable ormosil and they were characterised via Raman, Electrochemical Impedance Spectroscopy and Transmission Electron Microscopy. MPP was performed on the hybrid ionogels, resulting in three- dimensional microstructures that were characterised using scanning electron microscopy. It is clearly demonstrated that the molecular formulation of the ionogels, including the concentration of graphene and the zirconate network modifier, play a critical role in the conductivity of the ionogels and influence the resulting mechanical stability of the fabricated three-dimensional microstructures. This work aims to establish for the first time the relationship between the molecular design and condensation of materials in the physico-chemistry and dynamic of ionogels

Mechanical properties of bacterial cellulose synthesised by diverse strains of the genus Komagataeibacter

Bacterial cellulose (BC) has several current and potential future uses in the food industry because of its ability to form hydrogels with distinctive properties. The texture of BC hydrogels is determined by both the cellulose fibre network and the internal dispersed water. In this study, mechanical properties of hydrated BC synthesised by six different strains of Komagataeibacter genus were investigated with regards to their extensibility, compressive strength, relaxation ability, viscoelasticity and poroelasticity. The stress/strain at failure and Young's modulus were assessed by uniaxial tensile testing. The compressive strength, relaxation ability and viscoelasticity were measured via a series of compression and small amplitude oscillatory shear steps. A poroelastic constitutive modelling simulation was used to investigate the mechanical effects of water movement. The morphology of the BC fibril network under compression was observed via scanning electron microscopy. Results showed that the mechanics of BC were highly dependent on the cellulose concentration, as well as the morphology of the fibril network. BC synthesised by ATCC 53524 was the most concentrated (0.71 wt%), and exhibited high tensile properties, stiffness and storage moduli; whereas comparatively low mechanical properties were noted for BC produced by ATCC 700178 and ATCC 10245, which contained the lowest cellulose concentration (0.18 wt%). Small deformation responses (normal stress, G′) scaled with cellulose concentration for all samples, whereas larger deformation responses (Young's modulus, poroelasticity) depended on both cellulose concentration and additional factors, presumably related to network morphology. Increasing concentration and compressive coalescence of fibres in the integrated BC network reduced both the relaxation of the normal stress and the movement of water. This research aids the selection of bacterial strains to modulate the texture and mechanical properties of hydrated BC-based food systems

Cost-Utility Analysis of a Medication Review with Follow-Up Service for Older Adults with Polypharmacy in Community Pharmacies in Spain: The conSIGUE Program

© 2015, Springer International Publishing Switzerland. Background: The concept of pharmaceutical care is operationalized through pharmaceutical professional services, which are patient-oriented to optimize their pharmacotherapy and to improve clinical outcomes. Objective: The objective of this study was to estimate the incremental cost-effectiveness ratio (ICER) of a medication review with follow-up (MRF) service for older adults with polypharmacy in Spanish community pharmacies against the alternative of having their medication dispensed normally. Methods: The study was designed as a cluster randomized controlled trial, and was carried out over a time horizon of 6 months. The target population was older adults with polypharmacy, defined as individuals taking five or more medicines per day. The study was conducted in 178 community pharmacies in Spain. Cost-utility analysis adopted a health service perspective. Costs were in euros at 2014 prices and the effectiveness of the intervention was estimated as quality-adjusted life-years (QALYs). In order to analyze the uncertainty of ICER results, we performed a non-parametric bootstrapping with 5000 replications. Results: A total of 1403 older adults, aged between 65 and 94 years, were enrolled in the study: 688 in the intervention group (IG) and 715 in the control group (CG). By the end of the follow-up, both groups had reduced the mean number of prescribed medications they took, although this reduction was greater in the IG (0.28 ± 1.25 drugs; p < 0.001) than in the CG (0.07 ± 0.95 drugs; p = 0.063). Older adults in the IG saw their quality of life improved by 0.0528 ± 0.20 (p < 0.001). In contrast, the CG experienced a slight reduction in their quality of life: 0.0022 ± 0.24 (p = 0.815). The mean total cost was €977.57 ± 1455.88 for the IG and €1173.44 ± 3671.65 for the CG. In order to estimate the ICER, we used the costs adjusted for baseline medications and QALYs adjusted for baseline utility score, resulting in a mean incremental total cost of −€250.51 ± 148.61 (95 % CI −541.79 to 40.76) and a mean incremental QALY of 0.0156 ± 0.004 (95 % CI 0.008–0.023). Regarding the results from the cost-utility analysis, the MRF service emerged as the dominant strategy. Conclusion: The MRF service is an effective intervention for optimizing prescribed medication and improving quality of life in older adults with polypharmacy in community pharmacies. The results from the cost-utility analysis suggest that the MRF service is cost effective

The influence of initial xylose concentration, agitation, and aeration on ethanol production by Pichia stipitis from rice straw hemicellulosic hydrolysate

Rice straw hemicellulosic hydrolysate was used as fermentation medium for ethanol production by Pichia stipitis NRRL Y-7124. Shaking bath experiments were initially performed aiming to establish the best initial xylose concentration to be used in this bioconversion process. In the sequence, assays were carried out under different agitation (100 to 200 rpm) and aeration (V flask/V medium ratio varying from 2.5 to 5.0) conditions, and the influence of these variables on the fermentative parameters values (ethanol yield factor, Y P/S; cell yield factor, Y X/S; and ethanol volumetric productivity, Q P) was investigated through a 22 full-factorial design. Initial xylose concentration of about 50 g/l was the most suitable for the development of this process, since the yeast was able to convert substrate in product with high efficiency. The factorial design assays showed a strong influence of both process variables in all the evaluated responses. The agitation and aeration increase caused a deviation in the yeast metabolism from ethanol to biomass production. The best results (Y P/S = 0.37 g/g and Q P = 0.39 g/l.h) were found when the lowest aeration (2.5 V flask/V medium ratio) and highest agitation (200 rpm) levels were employed. Under this condition, a process efficiency of 72.5% was achieved. These results demonstrated that the establishment of adequate conditions of aeration is of great relevance to improve the ethanol production from xylose by Pichia stipitis, using rice straw hemicellulosic hydrolysate as fermentation medium.The financial support from Fapesp (Brazil) is gratefully acknowledged