bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced biomedical scientist cut-up role in colonic cancer reporting
Authors: Sanders Scott A , Smith Adrian , Carr Richard Allen , Roberts Sarah , Gurusamy Shiva , Simmons Emma
Published: March 2012

Aims

To extend the biomedical scientist (BMS) cut-up role to include gastrointestinal category D colorectal cancer resection specimens, and to address issues of quality and safety by presenting performance data from the first 50 BMS cut-up specimens in comparison with national guidelines and pathologist performance over the same timeframe.

Methods

Close mentoring and consultant supervision was carried out for every case with adherence to standard operating procedures and following colorectal cancer dataset guidelines as published by the Royal College of Pathologists. Performance targets were audited including anticipated spread of Dukes' stage, targets for mean lymph node harvest, percentage extramural vascular invasion and serosal involvement, and mean tumour blocks sampled. Histological pre-reporting of 20 cases was encouraged, and time spent by BMS and consultant at all stages of specimen reporting was noted.

Results

Performance targets were all exceeded by the BMS and compared favourably with pathologist performance. A measure of consultant cut-up and histology reporting time saved was identified.

Conclusions

Benefits of extending the BMS role to category D specimens may include BMS professional advancement, efficient use of consultant time and the development of a team approach to cancer reporting. The achievement of colorectal cancer performance targets and favourable comparison with pathologist performance implies there was no perceived detrimental effect on quality or safety and thus patient management.
‘The Anglo-Saxon disease’: a pilot study of the barriers to and facilitators of the use of randomised controlled trials of social programmes in an international context: Table 1
Authors: Roberts Helen , Petticrew Mark , Liabo Kristin , Macintyre Sally
Published: March 2012

Background

There appears to be considerable variation between different national jurisdictions and between different sectors of public policy in the use of evidence and particularly the use of randomised controlled trials (RCTs) to evaluate non-healthcare sector programmes.

Methods

As part of a wider study attempting to identify RCTs of public policy sector programmes and the reasons for variation between countries and sectors in their use, we carried out a pilot study which interviewed 10 policy makers and researchers in six countries to elicit views on barriers to and facilitators of the use of RCTs for social programmes.

Results

While in common with earlier studies, those interviewed expressed a need for unambiguous findings, timely results and significant effect sizes, users could, in fact, be ambivalent about robust methods and robust answers about what works, does not work or makes no difference, particularly where investment or a policy announcement was planned. Different national and policy sector cultures varied in their use of and support for RCTs.

Conclusions

In order to maximise the use of robust evaluations of public programmes across the world it would be useful to examine, systematically, cross-national and cross-sectoral variations in the use of different methods including RCTs and barriers to and facilitators of their use. Sound research methods, whatever their scientific value, are no guarantee that findings will be useful or used. ‘Stories’ have been shown to influence policy; those advocating the use of RCTs may need to provide convincing narratives to avoid repetition about their value.
Does income matter for troublesome neck pain? A population-based study on risk and prognosis
Authors: Palmlöf Lina , Skillgate Eva , Alfredsson Lars , Vingård Eva , Magnusson Cecilia , Lundberg Michael , Holm Lena W
Published: March 2012

Background

Studies have shown associations between higher income and better health, but income has not been studied in relation to neck pain. The aims of this cohort study were to assess the sex-specific role of disposable income for onset and prognosis of neck pain in the general population and if economic stress influences such potential associations.

Methods

Two subcohorts were identified in the Stockholm Public Health Cohort with data from 2002. Cohort I (risk cohort) included persons without neck pain (n=8348). Cohort II (prognostic cohort) included persons with occasional neck pain during the previous 6 months (n=10 523). Both cohorts were assessed for long duration troublesome neck pain (LDNP) in 2007. Individual income was defined as aggregated annual family income in 2002 with each family member assigned a weighted consumption share, based on salary, pensions and social benefits. LDNP in 2007 was defined as having had troublesome neck pain lasting for three or more consecutive months the previous 5 years. Association between income and LDNP, considering potential confounding, was investigated by multivariable logistic regression. Economic stress was tested as effect modifier between income and LDNP.

Results

In both cohorts, associations were found between lower income and a higher risk for LDNP. The results were similar between the sexes. Economic stress modified the associations in both cohorts.

Conclusions

Low income may be a risk as well as prognostic factor for developing LDNP. Furthermore, the results indicate that economic stress may be an underlying factor to consider when studying associations between income and neck pain.
The Regulatory Effect of Liuwei Dihuang Pills on Cytokines in Mice with Experimental Autoimmune Encephalomyelitis
Authors: Liu Yan , Zhao Hui , Zhang Jie , Zhang Ping , Li Ming , Qi Fang , Wang Yizhou , Kou Shuang , Zheng Qi , Wang Lei
Published: March 2012

The regulatory effect of Liuwei Dihuang Pills (LDP) was studied on cytokines in mice with experimental autoimmune encephalomyelitis (EAE), a model for human multiple sclerosis (MS), induced by immunization with MOG35-55 and complete Freund's adjuvant (CFA) supplemented with pertussis toxin (PTX). LDP was administrated orally for 40 days, and prednisone acetate (PA) was used as a control. The pathological changes in the spinal cords of mice were observed by light microscope with hematoxylin-eosin (HE) staining and transmission electron microscope (TEM). The protein and mRNA expression of tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta (TGF-β) in the spinal cords were assessed by immunohistochemistry and RT-PCR assay, and the cyclic adenosine monophosphate (cAMP) in mice plasma was measured by radioimmunoassay (RIA) on days 12, 25 and 40 post-immunization (PI). The results showed that inflammatory cells, demyelination and axonal loss were reduced, and that the protein and mRNA expression of TNF-α and the ratio of TNF-α/TGF-β were obviously decreased, to different extents. However, the levels of cAMP were enhanced in LDP-treated groups. These findings suggested that LDP regulates the cytokine balance in favor of T helper 1 (Th1)/regulatory T (Treg) cells, which depend on enhancement of cAMP levels. LDP has a potential role in the treatment of MS and other demyelinating diseases of the central nervous system.
Analysis of the Mechanisms Underlying the Vasorelaxant Action of Coptisine in Rat Aortic Rings
Authors: Gong Li-Li , Fang Lian-Hua , Qin Hai-Lin , Lv Yang , Du Guan-Hua
Published: March 2012

The aim of the present study was to evaluate the vasorelaxant effects of coptisine and its possible mechanisms in isolated rat aortic rings. Coptisine was evaluated on isolated rat aortic rings precontracted with norepinephrine (NE) and KCl. The mechanisms were evaluated in the presence or absence of specific pharmacological inhibitors. Coptisine (1 ~ 200 μM) relaxed NE (1 μM) or KCl (60 mM) induced sustained contraction with pEC50 values of 4.49 ± 0.48 and 4.85 ± 0.57 in a concentration dependent manner. Pretreatment with coptisine (10, 50 or 100 μM) also inhibited concentration-response curves to NE and KCl. The vasorelaxant effect of coptisine was attenuated significantly by endothelium removal, and incubation with Nω-nitro-L-arginine methyl ester (L-NAME, 100 μM), methylene blue (10 μM) and indomethacin (5 μM) partially reduced the vasorelaxant effect of coptisine. In endothelium-denuded rings, the vasorelaxant effect of coptisine was reduced significantly by 4-aminopyridine (4-AP, 100 μM), but not glibenclamide (10 μM) ortetraethylammonium (TEA, 5 mM). Coptisine also reduced NE-induced transient contraction in Ca2+ -free solution, and inhibited contraction induced by increasing external calcium in Ca2+ -free medium plus 60 mM KCl. It was concluded that coptisine induced both endothelium-dependent and -independent relaxation in rat aortic rings. The NO-cGMP mediated pathway may be involved in the endothelium-dependent relaxation and in the activation of voltage-dependent K+ channels, contributing in part to the endothelium-independent relaxation bycoptisine. Coptisine also blocks extracellular Ca2+ influx by interacting with both voltage- and receptor-operated Ca2+ channels.
Cytotoxic Effect of Eucalyptus citriodora Resin on Human Hepatoma HepG2 Cells
Authors: Shen Kun-Hung , Chen Zong-Tsi , Duh Pin-Der
Published: March 2012

The aim of this study was to evaluate the antiproliferative effect of Eucalyptus citriodora resin (ECR) on human hepatoma HepG2 cells. The results from MTT assay and LDH leakage analysis showed that water extracts of ECR (WEECR) in the dose range of 0–500 μg/ml displayed stronger cytotoxic effects on HepG2 cells than other organic solvent extracts of ECR. By flow cytometry analysis, WEECR slowed down the cell cycle at the G0/G1 phase after 24 h of incubation. Moreover, WEECR treatment induced an apoptotic response in HepG2 cells. WEECR-induced apoptosis was in association with the attenuation of mitochondrial transmembrane potentials (ΔΨ m ), increased Bax/Bcl-2 ratio and activation of caspase-3. In addition, WEECR contained high concentration of phenolics and flavonoids, which may be responsible for the potent cytotoxicity of WEECR on HepG2 cells. Taken together, WEECR may be a potent antihepatoma agent due to apoptosis in HepG2 cells.
ERRATUM: "DIRAC EQUATION FOR A COULOMB SCALAR, VECTOR AND TENSOR INTERACTION"
Authors: ZARRINKAMAR S. , HASSANABADI H. , RAJABI A. A.
Published: March 2012

Although our compact form of energy relation is correct, there is an error in the last energy relation reported in our recent paper, which is here corrected.
REGION OF INTEREST DETECTION BASED ON VISUAL PERCEPTION MODEL
Authors: ZHANG JING , ZHUO LI , ZHAO YINGDI
Published: March 2012

According to human vision theory, the image is conveyed from human visual system to brain when people have a look at. Different from previous work, the study reported in this paper attempts to simulate a more real and complex method for region of interest (ROI) detection and quantitatively analyze the correlation between users' visual perception and ROI. In this paper, a visual perception model-based ROI detection is proposed, which can be realized with an ordinary web camera. Visual perception model employs a combination of visual attention model and gaze tracking data to objectively detect ROIs. The work includes pre-ROI estimation using visual attention model, gaze data collection and ROI detection. Pre-ROIs are segmented by the visual attention model. Since eye feature extraction is critical to the accuracy and performance of gaze tracking, adaptive eye template and neural network are employed to predict gaze points. By computing the density of the gaze points, ROIs are ranked. Experimental results show that the accuracy of our ROI detection method can be raised as high as 97% and it is also demonstrated that our model can efficiently adapt to users' interests and match the objective ROI.
LANGUAGE, CATEGORIZATION, AND CONVENTION
Authors: NARENS LOUIS , JAMESON KIMBERLY A. , KOMAROVA NATALIA L. , TAUBER SEAN
Published: March 2012

Linguistic meaning is a convention. This article investigates how such conventions can arise for color categories in populations of simulated "agents". The method uses concepts from evolutionary game theory: A language game where agents assign names to color patches and is played repeatedly by members of a population. The evolutionary dynamics employed make minimal assumptions about agents' perceptions and learning processes. Through various simulations it is shown that under different kinds of reasonable conditions involving outcomes of individual games, the evolutionary dynamics push populations to stationary equilibria, which can be interpreted as achieving shared population meaning systems. Optimal population agreement for meaning is characterized through a mathematical formula, and the simulations presented reveal that for a wide variety of situations, optimality is achieved.
BRANE REALIZATIONS OF QUANTUM HALL SOLITONS AND LIE ALGEBRAS
Authors: BELHAJ A. , ELRHALAMI A. , FAHSSI N.-E. , KHAN M. J. I. , SAIDI E. H. , SEGUI A.
Published: March 2012

Using quiver gauge theories in (1+2)-dimensions, we give brane realizations of a class of Quantum Hall Solitons (QHS) embedded in Type IIA superstring on the ALE spaces with exotic singularities. These systems are obtained by considering two sets of wrapped D4-branes on 2-spheres. The space-time on which the QHS live is identified with the world-volume of D4-branes wrapped on a collection of intersecting 2-spheres arranged as extended Dynkin diagrams of Lie algebras. The magnetic source is given by an extra orthogonal D4-brane wrapping a generic 2-cycle in the ALE spaces. It is shown as well that data on the representations of Lie algebras fix the filling factor of the QHS. In case of finite Dynkin diagrams, we recover results on QHS with integer and fractional filling factors known in the literature. In case of hyperbolic bilayer models, we obtain amongst others values of filling factors appearing in graphene literature.
DYNAMICS WITH EXTERNAL FORCES REVISITED
Authors: TULCZYJEW WLODZIMIERZ M.
Published: March 2012

The study of isolated system is of little interest to physicists since it is not applicable to practical situations. Analytical mechanics should be brought closer to control theory. Behavior of a system coupled to external controlling devices should be examined. There is a class of controlling devices representable by external forces. We proposed a framework for describing the dynamics of mechanical devices subject to control by external forces. The original version of the theory was presented in G. Marmo, W. Tulczyjew and P. Urbański, Dynamics of autonomous systems with external forces, Acta Phys. Polon. B33 (2002) 1181–1240. The geometric constructions used in original paper are clarified. The Legendre–Fenchel transformation is described and the concept of external force is introduced. Liouville structures are defined.
MULTI-STATE CORRELATIONS AND FIDELITIES
Authors: FANNES M.
Published: March 2012

Correlations between states in a general quantum ensemble can be encoded in a Gram matrix that depends on a prescribed joint purification. This allows to establish an upper bound for the Holevo quantity χ. Optimizing over joint purifications is a hard problem. For small ensembles the connection with matrices of fidelities is investigated. General bounds are obtained for a linearized version of χ.
BUILDING AN ENTANGLEMENT MEASURE ON PHYSICAL GROUND
Authors: TERESI D. , NAPOLI A. , MESSINA A.
Published: March 2012

We introduce on physical grounds a new measure of multipartite entanglement for pure states. The function we define is discriminant and monotone under LOCC; moreover, it can be expressed in terms of observables of the system.
ANOMALIES AND MIXED STATES
Authors: BALACHANDRAN A. P. , DE QUEIROZ AMILCAR R.
Published: March 2012

There are many examples of quantum anomalies of continuous and discrete classical symmetries. Examples come from chiral anomalies in the Standard Model and gravitational anomalies in string theories. They occur when classical symmetries do not preserve the domains of quantum operators like the Hamiltonian. Here we show by a simple example, a particle on a circle, that anomalous symmetries can often be implemented at the expense of working with mixed states.
FOLDING AND UNFOLDING QUANTUM STATES
Authors: FERRO L. , IBORT A.
Published: March 2012

The reduction of a quantum system ("folding" a quantum system) is described as the reduction of its Lie–Jordan Banach algebra of observables with respect to Lie–Jordan Banach subalgebras and Jordan ideals. The space of states of the reduced Lie–Jordan Banach algebra is described in terms of unreduced states ("unfolding" states) as well as the GNS construction. A few examples are discussed.
Unsymmetrical phthalocyanines with cyclopalladated azo functions
Authors: Akkurt H. Yasemin Yenilmez , Okur Ali ihsan , Gül Ahmet
Published: March 2012

In this study, a synthetic procedure for unsymmetrical metallophthalocyanines of the form M[Pc(AB3)], where A and B refer to two different types of peripheral functionality, has been developed and the new compounds have been converted to monomeric and dimeric palladium complexes. Asymmetrically substituted phthalocyanines were synthesized with the well-known statistical condensation method, by using two differently substituted precursors, namely 4-(2-ethoxyethoxy)-1-2-dicyanobenzene (1) and 4-{4-[Z/E]-phenylazo]-1-naphthyl}oxy-1,2-dicyanobenzene (2). Consequently, electron-donating 2-ethoxyethoxy groups and electron-withdrawing palladium complex are present in the same structure. Cyclopalladation was performed with [Pd(PhCN)2Cl2] to yield the bis-μ-chloro-bridged dimers and subsequently, the corresponding monomers were obtained by refluxing with three equivalents of potassium acetylacetonate. The resulting products were purified by column chromatography and characterized by several chemical and spectroscopic analysis methods. All compounds have very high solubility in organic solvents due to the presence of 2-ethoxyethoxy moiety.
Efficient synthesis of 2-indolyl-1-nitroalkanes catalyzed by tetramethyl-tetra-3,4-pyridinoporphyrazinato copper(II) methyl sulfate
Authors: Safaei Elham , Sobhani Sara , Razavi Nasrin
Published: March 2012

A new method for the synthesis of 2-indolyl-1-nitroalkanes from indoles and β-nitrostyrene via Michael addition catalyzed by [ Cu (3,4-tmtppa)] (MeSO4)4 as a reusable catalyst under solvent-free conditions is described. This method has been also successfully applied for Michael addition of 3-methyl-1-phenyl-5-pyrazolone with β-nitrostyrenes.
Time travelers, flying heads, and second lives
Authors: Lewis Jason
Published: March 2012

Community + Culture features practitioner perspectives on designing technologies for and with communities. We highlight compelling projects and provocative points of view that speak to both community technology practice and the interaction design field as a whole.

Tad Hirsch, Editor
Personalized dynamic accessibility
Authors: Gajos Krzysztof Z. , Hurst Amy , Findlater Leah
Published: March 2012

In this forum we celebrate research that helps to successfully bring the benefits of computing technologies to children, older adults, people with disabilities, and other populations that are often ignored in the design of mass-marketed products.

Juan Pablo Hourcade, Editor
Detection and solution of software performance antipatterns in palladio architectural models (abstracts only)
Authors: Trubiani Catia , Koziolek Anne
Published: March 2012

Antipatterns are conceptually similar to patterns in that they document recurring solutions to common design problems. Performance Antipatterns document, from a performance perspective, common mistakes made during software development as well as their solutions. The definition of performance antipatterns concerns software properties that can include static, dynamic, and deployment aspects. Currently, such knowledge is only used by domain experts; the problem of automatically detecting and solving antipatterns within an architectural model had not yet been empirically addressed. In this paper we present an approach to automatically detect and solve software performance antipatterns within the Palladio architectural models: the detection of an antipattern provides a software performance feedback to designers, since it suggests the architectural alternatives to overcome specific performance problems. We implemented the approach and a case study is presented to demonstrate its validity. The system performance under study has been improved by 50% with the use of antipatterns' solutions.
Relative roles of instruction count and cycles per instruction in WCET estimation (abstracts only)
Authors: Ravindar Archana , Srikant Y. N.
Published: March 2012

Most of the existing WCET estimation methods directly estimate execution time, ET, in cycles. We propose to study ET as a product of two factors, ET = IC * CPI, where IC is instruction count and CPI is cycles per instruction. Considering directly the estimation of ET may lead to a highly pessimistic estimate since implicitly these methods may be using worst case IC and worst case CPI. We hypothesize that there exists a functional relationship between CPI and IC such that CPI=f(IC). This is ascertained by computing the covariance matrix and studying the scatter plots of CPI versus IC. IC and CPI values are obtained by running benchmarks with a large number of inputs using the cycle accurate architectural simulator, Simplescalar on two different architectures. It is shown that the benchmarks can be grouped into different classes based on the CPI versus IC relationship. For some benchmarks like FFT, FIR etc., both IC and CPI are almost a constant irrespective of the input. There are other benchmarks that exhibit a direct or an inverse relationship between CPI and IC. In such a case, one can predict CPI for a given IC as CPI=f(IC). We derive the theoretical worst case IC for a program, denoted as SWIC, using integer linear programming(ILP) and estimate WCET as SWIC*f(SWIC). However, if CPI decreases sharply with IC then measured maximum cycles is observed to be a better estimate. For certain other benchmarks, it is observed that the CPI versus IC relationship is either random or CPI remains constant with varying IC. In such cases, WCET is estimated as the product of SWIC and measured maximum CPI. It is observed that use of the proposed method results in tighter WCET estimates than Chronos, a static WCET analyzer, for most benchmarks for the two architectures considered in this paper.
An automatic trace based performance evaluation model building for parallel distributed systems (abstracts only)
Authors: Mizan Ahmad , Franks Greg
Published: March 2012

Performance models can be built at early stages of software development cycle to aid software designers to assess design alternatives and identify fundamental design pitfalls before the implementation phase starts. These models are flexible for varying operational conditions and design alternatives; however, their creation is not trivial and requires considerable efforts. This paper addresses this problem by introducing automation in process of Layered Queuing Network (LQN) performance model creation for traces of events generated from instrumented software programs in the nodes of a distributed parallel software application. The event-traces are created based on a new timestamp format, which is independent of physical time and uses extremely low count elements. A set of post-mortem methodologies have been introduced to identify the interactions between the service nodes of the parallel distributed software application and determine their workload activities, while supporting concurrent executions in the nodes. It can capture Forward, Asynchronous, Synchronous and loops of Asynchronous or Forward interactions. The final result is a framework of methodologies, specifications and tools which is appropriate for model-based performance evaluation parallel distributed software applications.
Hierarchical performance measurement and modeling of the linux file system (abstracts only)
Authors: Nguyen Hai , Apon Amy
Published: March 2012

File systems are very important components in a computer system. File system simulation can help to predict the performance of new system designs. It offers the advantages of the flexibility of modeling and the cost and time savings when utilizing simulation instead of full implementation. Being able to predict end-to-end file system performance against a pre-defined workload can help system designers to make decisions that could affect their entire product line, affecting several million dollars of investment. This paper presents a detailed simulation-based performance model of the Linux ext3 file system. The model is developed using Colored Petri Nets. A performance study using the model shows that the obtained results are close to the expected behavior of the real file system. The model shows that file system parameters have significant impact on the performance of the I/O when compared to the parameters of the disk subsystem.
Adaptive workload shaping for power savings on disk drives (abstracts only)
Authors: Mountrouidou Xenia , Riska Alma , Smirni Evgenia
Published: March 2012

In order to reduce the amount of power consumption in data centers, it is becoming necessary to shut off or slow down disks that are not actively serving user requests. In addition to exploiting disk drive idleness, system features are in place that shape a disk's workload by redirecting portions of it elsewhere, with the goal to expand the periods of idleness and the potential for power savings. In this paper, we propose several workload shaping techniques that determine which part of the working set to copy elsewhere using temporal and spatial access frequencies in the workload. These workload shaping techniques, used within an analytic estimation methodology, enable a fully automated framework that determines on-line for the current workload which, if any, shaping technique to activate such that the power saving benefits are maximized without violating performance targets. Extensive trace-driven evaluation shows that the proposed workload shaping techniques complement each-other with regard to their abilities to enhance idleness in disk drives for a wide range of workload characteristics. This results to added power savings in a data center even when performance targets are stringent and workloads intensive.
Assessment of high-performance smart metering for the web service enabled smart grid era (abstracts only)
Authors: Karnouskos Stamatis , da Silva Per Goncalves , Ilic Dejan
Published: March 2012

The electricity network is undergoing a significant change towards a more adaptive, intelligent, self-managing, collaborative and information-driven grid. According to the smart grid vision, any electronic device connected to it will be able to communicate its consumed or produced energy almost in real time. Based on the analysis of this newly acquired information, a new generation of services and decision support systems can be realized, enabling more intelligent decisions, and ultimately a more efficient energy system. Therefore, high-performance acquisition of smart metering information from large scale distributed infrastructures is of key importance for the upcoming Internet-based enterprise services and mash-up applications. We have used open source software to build a web service-based advanced metering infrastructure of simulated smart meters, concentrators, and a smart metering platform, all interconnected via web services. We measure in a methodological fashion the performance of the various components of the architecture and evaluate their limitations. Finally we identify key performance indicators that need to be considered when deploying large-scale smart metering systems, and discuss on challenges and directions that arise.
Adaptive run-time performance optimization through scalable client request rate control (abstracts only)
Authors: Starnberger Guenther , Froihofer Lorenz , Goeschka Karl M.
Published: March 2012

Today's Internet-scale computing systems often run at a low average load with only occasional peak performance demands. Consequently, computing resources are often overdimensioned, leading to high costs. While load control techniques between clients and servers can help to better utilize a given system, these techniques can place a significant communication and computation load on servers. To improve on these issues, we contribute with scalable techniques for client-request rate control, achieved through integration of (i) a scalable distributed feedback channel to transmit control information from the server to the clients with (ii) decoupling strategies that allow to constrain and filter client requests directly at the client, illustrated in the area of first-price sealed-bid online auctions, and (iii) a PID (Proportional-Integral-Derivative) controller that adaptively controls the input parameters of those decoupling strategies to facilitate an optimal server utilization. In contrast to related work, we can hence optimize server load directly at the source through rate control of the clients. Our evaluations show that this setup supports large sets of clients before the controller becomes unstable.
Tracking adaptive performance models using dynamic clustering of user classes (abstracts only)
Authors: Ghanbari Hamoun , Barna Cornel , Litoiu Marin , Woodside Murray , Zheng Tao , Wong Johnny , Iszlai Gabriel
Published: March 2012

Estimation techniques have been largely applied to track hidden performance parameters (e.g. service demands) of web based software systems. In this paper we investigate dynamic multiclass modeling of such systems, with variable classes of service, aiming at finding a low complexity model yet with enough accuracy. We propose a combination of clustering algorithm and tracking filter for effective grouping of classes of services. The tracking estimator is based on a layered queuing model with parameters for CPU demands and the user load intensity of each class of service. Clustering uses the K-means algorithm. The target application is autonomic control of web clusters, where changes occur at different rates and amplitudes and at random time instants. Experiments show that the tracking is effective, and reveal good filter settings for different variations.
A capacity planning process for performance assurance of component-based distributed systems (abstracts only)
Authors: Roy Nilabja , Dubey Abhishek , Gokhale Aniruddha , Dowdy Larry
Published: March 2012

For service providers of multi-tiered component-based applications, such as web portals, assuring high performance and availability to their customers without impacting revenue requires effective and careful capacity planning that aims at minimizing the number of resources, and utilizing them efficiently while simultaneously supporting a large customer base and meeting their service level agreements. This paper presents a novel, hybrid capacity planning process that results from a systematic blending of 1) analytical modeling, where traditional modeling techniques are enhanced to overcome their limitations in providing accurate performance estimates; 2) profile-based techniques, which determine performance profiles of individual software components for use in resource allocation and balancing resource usage; and 3) allocation heuristics that determine minimum number of resources to allocate software components. Our results illustrate that using our technique, performance (i.e., bounded response time) can be assured while reducing operating costs by using 25% less resources and increasing revenues by handling 20% more clients compared to traditional approaches.
MassConf
Authors: Zheng Wei , Bianchini Ricardo , Nguyen Thu D.
Published: March 2012

Configuring modern enterprise software can be extremely difficult because their behaviors often depend on large numbers of configuration parameters. Software vendors can simplify the configuration process for new users by collecting and using configuration information from existing users. In particular, we observe that (1) a "good" configuration may work well for many different users, and (2) multiple configurations may work well for each user. We leverage these observations to design MassConf, a system that collects and uses existing configurations to automatically configure new software installations. Our evaluations with a case study confirm our observations and show that MassConf successfully reaches the targets of many more new installations than an existing efficient optimization algorithm.
Global cost diversity aware dispatch algorithm for heterogeneous data centers (abstracts only)
Authors: Sankaranarayanan Ananth Narayan , Sharangi Somsubhra , Fedorova Alexandra
Published: March 2012

Large, Internet based companies service user requests from multiple data centers located across the globe. These data centers often house a heterogeneous computing infrastructure and draw electricity from the local electricity market.Reducing the electricity costs of operating these data centers is a challenging problem, and in this work, we propose a novel solution which exploits both the data center heterogeneity and global electricity market diversity to reduce data center operating cost. We evaluate our solution in our test-bed that simulates a heterogeneous data center, using real-world request workload and real-world electricity prices. We show that our strategies achieve cost and energy saving of at least 21% over a naive load balancing scheme that distributes requests evenly across data centers, and outperform existing solutions which either do not exploit the electricity market diversity or do not exploit data center hardware diversity.
Performance evaluation for software migration (abstracts only)
Authors: Al-Azzoni Issam , Zhang Lei , Down Douglas G.
Published: March 2012

Advances in technology and economical pressure have forced many organizations to consider the migration of their legacy systems to newer platforms. Legacy systems typically provide mission critical services vital for an organization's business needs. These systems are usually very large and highly complex with little or no documentation. Furthermore, fewer people can understand and maintain these systems. While several techniques exist to verify the functionality of the migrated system, the literature is still lacking methods to effectively assess the performance impact of software migration. In this paper, we propose a new method designed specifically to address performance evaluation in software migration projects. The new method uses simple models and incorporates techniques for model validation and resource demand mapping for performance evaluation and capacity planning.
Modular performance modelling for mobile applications (abstracts only)
Authors: Arijo Niaz , Heckel Reiko , Tribastone Mirco , Gilmore Stephen
Published: March 2012

We propose a model-based approach to analysing the performance of mobile applications where physical mobility and state changes are modelled by graph transformations from which a model in the Performance Evaluation Process Algebra (PEPA) is derived. To fight scalability problems with state space generation we adopt a modular solution where the graph transformation system is decomposed into views, for which labelled transition systems (LTS) are generated separately and later synchronised in PEPA.We demonstrate that the result of this modular analysis is equivalent to that of the monolithic approach and evaluate practicality and scalability by means of a case study.
RMS-TM
Authors: Kestor Gokcen , Karakostas Vasileios , Unsal Osman S. , Cristal Adrian , Hur Ibrahim , Valero Mateo
Published: March 2012

Transactional Memory (TM) has been proposed as an alternative concurrency mechanism for the shared memory parallel programming model. Its main goal is to make parallel programming for Chip Multiprocessors (CMPs) easier than using the traditional lock synchronization constructs, without compromising the performance and the scalability. This topic has received substantial research attention and several TM designs have been proposed using various TM benchmarks. We believe that the evaluation of TM proposals would be more solid if it included realistic applications, that address on-going TM research issues, and that provide the potential for straightforward comparison against locks.

In this paper, we introduce RMS-TM, a Transactional Memory benchmark suite composed of seven real-world applications from the Recognition, Mining and Synthesis (RMS) domain. In addition to featuring current TM research issues such as nesting and I/O and system calls inside transactions, the RMS-TM applications also provide a mix of short and long transactions with small/large read and write sets with low/medium/high contention rates. These characteristics, as well as providing lock-based versions of the applications, make RMS-TM a useful TM tool. Current TM benchmarks do not explore all these features. In our evaluation with selected STM and HTM systems, we find that our benchmark suite is also scalable, which is useful for evaluating TM designs on high core counts.
Automatic estimation of performance requirements for software tasks of mobile devices (abstracts only)
Authors: Schwarzer Simon , Peschlow Patrick , Pustina Lukas , Martini Peter
Published: March 2012

This paper introduces a new method to predict performance requirements of mobile devices' software tasks using system models describing the hardware and software. With the help of clustering algorithms and linear regression, behavioral models of software tasks are generated automatically. These models are used to project the runtime of representative parts of the software tasks. The runtime of representative execution parts is determined with instruction-accurate simulations which are not feasible for whole executions. The inputs for the projection task a model of the hardware platform and input data parameters, especially the data size. A major advantage of this approach is that the developers do not have to estimate the performance requirements themselves. In this way the method helps to seamlessly integrate the performance analysis process into the development process. The paper introduces the ideas in detail and presents an evaluation of the proposed method for typical software tasks of mobile devices.
Improving the efficiency of information collection and analysis in widely-used IT applications (abstracts only)
Authors: Blagodurov Sergey , Arlitt Martin
Published: March 2012

Modern IT environments collect and analyze increasingly large volumes of data for a growing number of purposes (e.g., automated management, security, regulatory compliance, etc.). Simultaneously, such environments are challenged by the need to minimize their environmental footprints. A general solution to this problem is to utilize IT resources more efficiently. This paper describes our work to systematically evaluate the inefficiencies in the information collection and analysis of several widely-used IT applications, to implement a more efficient solution, and to quantify the improvements. In particular, the logging of HTTP transactions by the Apache Web server and of network events by the Bro intrusion detection system are converted from text files to DataSeries. The costs of recording, storing and analyzing the information in the different formats are thoroughly evaluated and compared. We converted the text logs to DataSeries online, with no discernable overhead on the logging applications. We achieved upto a 7x decrease in the logfile sizes relative to the sizes of the default text logs, and speedups of 3x-8.4x to analyze the logfiles.
On estimation problems for the G/G/∞ Queue
Authors: Feng Hanhua , Dube Parijat , Zhang Li
Published: March 2012

We consider estimation problems in G/G/∞ queue under incomplete information. Specifically, we are interested in scenarios where it is infeasible to track each individual job in the system and only aggregate statistics are known or observable. We first show that the minimum expected square estimator for the queue length process can be written as the sum of the minimum square estimators for an indicator function associated with each job, which is simply the survival function of the service time variable for each job. We also obtain tight lower and upper bounds on the time average of the square estimation error. Next we look at the inverse problem of estimating the service time distribution when the observed process is only the queue length process. We develop an on-line stochastic-optimization based estimation algorithm for the service time distribution and study its convergence under different parameter settings.
The power of partial power of two choices
Authors: Akgun Osman T. , Righter Rhonda , Wolff Ronald
Published: March 2012

It is well known that the expected waiting time for customers routed to several parallel queues decreases dramatically when customers are routed to the shortest of two randomly chosen queues, rather than being arbitrarily assigned to one of the queues, and that the further improvement when there are three queues to choose from is much less than the improvement when moving from one to two queues (the power of two [5]). We consider the power of two effect when a subset of customers are flexible, and can choose the shortest of two queues, while the remainder are dedicated, and have no routing choice. We show that the stationary expected waiting time is decreasing and convex in the proportion of flexible customers. Our results show that having a small proportion of flexible customers has nearly as much benefit as having full power of two choices.
Geographical load balancing with renewables
Authors: Liu Zhenhua , Lin Minghong , Wierman Adam , Low Steven H. , Andrew Lachlan L.H.
Published: March 2012

Given the significant energy consumption of data centers, improving their energy efficiency is an important social problem. However, energy efficiency is necessary but not sufficient for sustainability, which demands reduced usage of energy from fossil fuels. This paper investigates the feasibility of powering internet-scale systems using (nearly) entirely renewable energy. We perform a trace-based study to evaluate three issues related to achieving this goal: the impact of geographical load balancing, the role of storage, and the optimal mix of renewables. Our results highlight that geographical load balancing can significantly reduce the required capacity of renewable energy by using the energy more efficiently with "follow the renewables" routing. Further, our results show that small-scale storage can be useful, especially in combination with geographical load balancing, and that an optimal mix of renewables includes significantly more wind than photovoltaic solar.
ReRack
Authors: Brown Michael , Renau Jose
Published: March 2012

Data centers operating cost are dominated by their power consumption. Renewable energy sources can reduce the operating costs when correctly selected. Nevertheless, this is a non trivial task because it should consider different energy sources (wind, solar), storage alternatives (batteries, grid-tie), workload, historical weather patterns, incentives, and service agreement penalties. These are the basic factors, but the model should be extensive to consider other factors like power gating support.

This paper introduces ReRack, an extensible simulation infrastructure that can be used to evaluate the energy cost of a data center using renewable energy sources. ReRack is composed of two main components, a simulation and an optimization component. The simulation component explores the cost effectiveness of renewable energy generation. It requires a model that can simulate both the data center power usage and the location-dependent variability of the power generation source (solar and wind). The ReRack optimization component finds the best ratio of renewable energy sources for a given location and workload.
Fluid computation of the performance
Authors: Stefanek Anton , Hayden Richard A. , Bradley Jeremy T.
Published: March 2012

Recent fluid analysis techniques allow fast and effcient calculation of complex reward metrics and passage time probabilities in systems with very large state space. We demonstrate how to incorporate these to look at the trade-off between service level agreement (SLA) satisfaction and complex reward optimisation. We show how the uid analysis naturally leads to a constrained global optimisation problem with embedded differential equations. We illustrate this problem on an abstract model of a virtualised execution environment that accurately captures resource allocations.
Improving Hadoop performance in intercloud environments
Authors: Kim Shingyu , Won Junghee , Han Hyuck , Eom Hyeonsang , Yeom Heon Y.
Published: March 2012

Intercloud is a federated environment of private clusters and public clouds. The performance of Hadoop could be degraded significantly in intercloud environments. Because previous solutions for intercloud environments rely on speculative execution, they require additional cost in the cloud. In this paper, we propose a new task scheduler that improves performance without the help of speculative execution in intercloud environments.
Improving performance of MapReduce framework on InterCloud by avoiding transmission of unnecessary data
Authors: Choi Seungmi , Kim Shingyu , Han Hyuck , Yeom Heon Y.
Published: March 2012

Recently, cloud computing and MapReduce have become attractive computing environments as the need for data processing rapidly increases. This inflation in the demand for resources led to the introduction of InterCloud, which provisions resources from two or more cloud service providers. However, when MapReduce applications run on InterCloud environments, they underperform contrary to our expectations. In this paper, we suggest a technique that mitigates the performance problem of MapReduce applications on InterCloud environments. As shown in our preliminary results, our technique leads to up to five times better performance in InterCloud environments.
Mean-field approximations for performance models with generally-timed transitions
Authors: Hayden Richard A.
Published: March 2012

We show how the popular mean-field approach for analysing Markovian models of massively-parallel computer systems can be extended to incorporate generally-timed transitions. Specifically, in the context of a simple peer-to-peer software update model, we show how systems of delay differential equations can be formally derived from such models. Finally, we verify empirically that the approximation is accurate and converges under the usual mean-field scaling.
Catalytic Transformation of Tall Oil into Biocomponent of Diesel Fuel
Authors: Mikulec Jozef , Kleinová Andrea , Cvengroš Ján , Joríková L'udmila , Banič Marek
Published: March 2012

One of the conventional kraft pulp mills produce crude tall oil which is a mixture of free fatty acids, resin acids, sterols, terpenoid compounds, and many others. This study is devoted to the issue of direct transformation of crude tall oil in a mixture with straight-run atmospheric gas oil to liquid fuels using three different commercial hydrotreating catalysts. Diesel fuel production is an alternative to incineration of these materials. High catalytic activity was achieved for all tested catalysts in temperature range 360–380°C, under 5.5 MPa hydrogen pressure and ratio H2/feedstock 500–1000 l/l. Crude tall oil can be converted to diesel oil component via simultaneous refining with straight-run atmospheric gas oil on NiMo/Al2O3and NiW/Al2O3-zeolite catalysts. All tested catalysts had very good hydrodenitrogenation activity and high liquid yield were at tested conditions.
Exponentiated Gamma Distribution: Different Methods of Estimations
Authors: Shawky A. I. , Bakoban R. A.
Published: March 2012

The exponentiated gamma (EG) distribution and Fisher information matrices for complete, Type I, and Type II censored observations are obtained. Asymptotic variances of the different estimators are derived. Also, we consider different estimators and compare their performance through Monte Carlo simulations.