bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction in NOx and CO Emissions in Stoichiometric Diesel Combustion Using a Three-Way Catalyst
Authors: Kim Junghwan , Reitz Rolf D. , Park Sung Wook , Sung Kian
Published: April 2010

Experimental and numerical studies were performed to investigate the simultaneous reduction in NOx and CO for stoichiometric diesel combustion with a three-way catalyst. A single-cylinder engine was used for the experiments and KIVA simulations were used in order to characterize the combustion efficiency and emissions of throttled stoichiometric diesel combustion at 0.7 bar boost pressure and 90 MPa injection pressure. In addition, the efficiency of emission conversion with three-way catalysts in stoichiometric diesel combustion was investigated experimentally. The results showed CO and NOx emissions can be controlled with the three-way catalyst in spite of the fact that CO increases more at high equivalence ratios compared with conventional diesel combustion (i.e., lean combustion). At a stoichiometric operation, the three-way catalyst reduced CO and NOx emissions by up to 95%, which achieves lower emissions compared with conventional diesel combustion or low temperature diesel combustion, while keeping better fuel consumption than a comparable gasoline engine.
Combining Instantaneous Temperature Measurements and CFD for Analysis of Fuel Impingement on the DISI Engine Piston Top
Authors: Cho Kukwon , Grover Ronald O. , Assanis Dennis , Filipi Zoran , Szekely Gerald , Najt Paul , Rask Rod
Published: April 2010

A two-pronged experimental and computational study was conducted to explore the formation, transport, and vaporization of a wall film located at the piston surface within a four-valve, pent-roof, direct-injection spark-ignition engine, with the fuel injector located between the two intake valves. Negative temperature swings were observed at three piston locations during early injection, thus confirming the ability of fast-response thermocouples to capture the effects of impingement and heat loss associated with fuel film evaporation. Computational fluid dynamics (CFD) simulation results indicated that the fuel film evaporation process is extremely fast under conditions present during intake. Hence, the heat loss measured on the surface can be directly tied to the heating of the fuel film and its complete evaporation, with the wetted area estimated based on CFD predictions. This finding is critical for estimating the local fuel film thickness from measured heat loss. The simulated fuel film thickness and transport corroborated well temporally and spatially with measurements at thermocouple locations directly in the path of the spray, thus validating the spray and impingement models. Under the strategies tested, up to 23% of fuel injected impinges upon the piston and creates a fuel film with thickness of up to 1.2 μm. In summary, the study demonstrates the usefulness of heat flux measurements to quantitatively characterize the fuel film on the piston top and allows for validation of the CFD code.
Analysis of the Effects of Pulsations on the Operational Stability of Centrifugal Compressors in Mixed Reciprocating and Centrifugal Compressor Stations
Authors: Brun Klaus , Kurz Rainer
Published: April 2010

Mixed operation with both centrifugal and reciprocating compressors in a compression plant poses significant operational challenges as pressure pulsations and machine mismatches lead to centrifugal compressors’ instabilities or poor performance. Arrangements with reciprocating compressors placed in series with centrifugal compressors generally lead to higher suction/discharge pulsations on the centrifugal compressor than conventional parallel operation. This paper demonstrates that by properly analyzing and designing the interconnecting piping between the compressors, utilizing pulsation attenuation devices, and matching the compressors’ volumetric-flow rates, a satisfactory functional compression system design can be achieved for even the worst cases of mixed centrifugal and reciprocating compressor operation. However, even small analysis errors, design deviations, or machine mismatches result in a severely limited (or even inoperable) compression system. Also, pulsation attenuation often leads to a significant pressure loss in the interconnect piping system. Utilizing analysis tools in the design process that can accurately model the transient fluid dynamics of the piping system, the pulsation attenuation devices, and the compressor machine behaviors is critical to avoid potentially costly design mistakes and minimize pressured losses. This paper presents the methodology and examples of such an analysis using a 1D transient Navier–Stokes code for complex compression piping networks. The code development, application, and example results for a set of mixed operational cases are discussed. This code serves as a design tool to avoid critical piping layout and compressor matching mistakes early in the compressor station design process.
The Efficiency of Turbocharger Compressors With Diabatic Flows
Authors: Casey Michael V. , Fesich Thomas M.
Published: April 2010

In most compressors the flow is adiabatic, but in low-speed turbochargers, the compression process has both heat transfer and work input. This paper examines different compressor efficiency definitions for such diabatic flows. Fundamental flaws in the use of the isentropic efficiency for this purpose are identified, whereas the polytropic efficiency can be used with or without heat transfer without ambiguities. The advantage of the polytropic approach for a practical application is demonstrated by analyzing the heat transfer in a turbocharger compressor. A simple model of the heat transfer allows a correction for this effect on the polytropic efficiency at low-speed to be derived. Compressor characteristics that have been corrected for this surprisingly large effect maintain a much higher efficiency down to low-speeds.
Elastohydrodynamics Applied to Active Tilting-Pad Journal Bearings
Authors: Haugaard Asger M. , Santos Ilmar F.
Published: April 2010

The static and dynamic properties of tilting-pad journal bearings with controllable radial oil injection are investigated theoretically. The tilting pads are modeled as flexible structures and their behavior is described using a three-dimensional finite element framework and linear elasticity. The oil film pressure and flow are considered to follow the modified Reynolds equation, which includes the contribution from controllable radial oil injection. The Reynolds equation is solved using a two-dimensional finite element mesh. The rotor is considered to be rigid in terms of shape and size, but lateral movement is permitted. The servovalve flow is governed by a second order ordinary differential equation, where the right hand side is controlled by an electronic input signal. The constitutive flow-pressure relationship of the injection orifices is that of a fully developed laminar velocity profile and the servovalve is introduced into the system of equations by a mass conservation consideration. The Reynolds equation is linearized with respect to displacements and velocities of the nodal degrees of freedom. When all nodal points satisfy static equilibrium, the system of equations is dynamically perturbed and subsequently condensed to a 2×2 system, keeping only the lateral motion of the rotor. As expected, bearing dynamic coefficients are heavily influenced by the control parameters and pad compliance.
Simulation of Fretting Wear in Half-Plane Geometries—Part II: Analysis of the Transient Wear Problem Using Quadratic Programming
Authors: Nowell D.
Published: April 2010

This paper presents an efficient numerical method based on quadratic programming, which may be used to analyze fretting contacts in the presence of wear. The approach provides an alternative to a full finite element analysis, and is much less computationally expensive. Results are presented for wear of a Hertzian contact under full sliding and under partial slip. These are compared with previously published finite element analyses of the same problem. Results are also obtained for the fully worn problem by allowing a large number of wear cycles to accumulate. The predicted traction distributions for this case compare well with the fully worn analytical solution presented in part one of this paper.
The Critical Conditions for Tribo-Demagnetization of Perpendicular Magnetic Recording Disk Under Sliding Contact
Authors: Jiang W. F. , Diao D. F.
Published: April 2010

The critical conditions (critical stress and critical temperature) for the demagnetization of perpendicular magnetic recording disks were investigated. A tribo-demagnetization test of a perpendicular magnetic recording disk with a low load ball-on-disk system and the scan of the disk with the magnetic head were sequentially carried out to evaluate the critical force and sliding velocity for the occurrence of demagnetization, and the relationship between the two critical factors. Then, a finite element model using thermomechanical coupling was developed to calculate the critical stress and temperature of the magnetic disk based on the critical force and sliding velocity of the experiment result. Finally, a method based on the tribo-demagnetization test in combination with finite element analysis to calculate the critical conditions for the demagnetization of the perpendicular magnetic recording disk under sliding contact was proposed.
Assessment of Elliptical Conformal Hertz Analysis Applied to Constant Velocity Joints
Authors: Lee Chul-Hee , Polycarpou Andreas A.
Published: April 2010

To analyze the contact between two spherical bodies with different radii of curvature, the three-dimensional (3D) Hertz theory for elliptical contact is typically used. When the two contacting bodies have high conformity, such as the case for ball-in-groove, the Hertz theory may break down. In this research, finite element analysis (FEA) was used to assess the validity of 3D Hertz theory as found in the roller-housing contact of constant velocity joints. The contact area, normal approach, and contact pressure results show that Hertz agrees with FEA predictions for low compressive loads, where the contact ellipse is within the geometrical contact dimensions. At higher loads the contact ellipse extends beyond the contacting geometrical dimensions and the simplified analytical Hertz results diverge from the FEA results.
A Scale Dependent Simulation of Liquid Lubricated Textured Surfaces
Authors: Jackson Robert L.
Published: April 2010

Over the past few years, the importance of nanoscale technology in industries, such as data storage, micro-electro-mechanical systems (MEMs), and conventional sliding and rolling element bearings, has increased significantly. This is due to increased performance criteria and emerging technologies at smaller scales. One way to increase tribological performance of such applications is through nanoscale surface texturing. These textures will allow for precise control of the performance of lubricated surfaces with very thin films. This work examines how the behavior of the lubricant changes as the geometry of the texture is decreased toward the nanoscale. This work uses existing scale dependent lubrication theories to model the hydrodynamic lubrication of textured surfaces in attempt to predict how nanoscale textures will perform. The theoretical results show that the scale effects of a lubricant between textured surfaces can decrease the load carrying capacity while also decreasing the friction force. Overall, the friction force decreases more than the load carrying capacity and so the effective friction coefficient is decreased. It should be noted that relative to larger scale textured surfaces, the load support can also decrease with the decreasing scale of the texture.
Erosive Wear Model of Slurry Pump Impeller
Authors: Batalović Veselin
Published: April 2010

Erosion wear is a serious problem that constantly accompanies the operation of the system for hydraulic transportation of solid materials. The consequences are the loss of material (steel), loss of work element’s working capacity, great operational expenses, etc. The choice of new materials for working elements, improvements in construction, and optimization of the slurry flow are all various ways of softening the consequences of erosion wear that reflects on the working life of the hydraulic transportation pump’s elements. Data, which would be used for acquiring the above mentioned goals, are mainly acquired through testing in laboratory or semi industrial conditions. It has been proved that numerous influential and time effected values, complex and long term research, etc., make this job an expensive one, and the results are often solely applicable to specific operating conditions. To resolve this problem, the author suggests a combined approach: shorthand experimental researches and mathematical modeling of erosion wear. The suggested model, used for defining the mass loss of the working element affected by solid particles in the slurry, offers the possibility of introducing a greater number of influential values, some of which have a coincidental character. Through the realization of this model, wear intensity data is acquired, which are practically noncoincidental values with a great degree of reliability, and which greatly coincide with the results acquired through measurements conducted on the test facility.
Optically anisotropic infinite cylinder above an optically anisotropic half space: Dispersion interaction of a single-walled carbon nanotube with a substrate
Authors: Šiber A. , Rajter R. F. , French R. H. , Ching W. Y. , Parsegian V. A. , Podgornik R.
Published: April 2010

A complete form of the van der Waals dispersion interaction between an infinitely long anisotropic semiconducting/insulating thin cylinder and an anisotropic half space is derived for all separations between the cylinder and the half space. The derivation proceeds from the theory of dispersion interactions between two anisotropic infinite half spaces as formulated in Phys. Rev. A 71, 042102 (2005). The approach is valid in the retarded as well as nonretarded regimes of the interaction and is coupled with the recently evaluated ab initio dielectric response functions of various semiconducting/insulating single wall carbon nanotubes, enables the authors to evaluate the strength of the van der Waals dispersion interaction for all orientation angles and separations between a thin cylindrical nanotube and the half space. The possibility of repulsive and/or nonmonotonic dispersion interactions is examined in detail.
SUMOylation of the Transcriptional Co-Repressor KAP1 Is Regulated by the Serine and Threonine Phosphatase PP1
Authors: Li Xu , Lin H. Helen , Chen Hanqing , Xu Xingzhi , Shih Hsiu-Ming , Ann David K.
Published: April 2010

Two isoforms of protein phosphatase 1 coordinate the recovery of cells from genotoxic stress.
The Ras-MAPK Signal Transduction Pathway
Authors: Thatcher Jack D.
Published: April 2010

Animated lessons illustrate a canonical signaling pathway activated by various hormones and growth factors.
The cAMP Signal Transduction Pathway
Authors: Thatcher Jack D.
Published: April 2010

Animated lessons illustrate cAMP signaling initiated by activation of G protein–coupled receptors.
The Inositol Trisphosphate (IP
3
) Signal Transduction Pathway
Authors: Thatcher Jack D.
Published: April 2010

Animated lessons illustrate a signaling module that operates downstream of various hormones and growth factors.
Embryonated Eggs as an Alternative Infection Model To InvestigateAspergillus fumigatusVirulence
Authors: Jacobsen Ilse D. , Große Katharina , Slesiona Silvia , Hube Bernhard , Berndt Angela , Brock Matthias
Published: April 2010

Infection models are essential tools for studying microbial pathogenesis. Murine models are considered the “gold standard” for studyingin vivoinfections caused byAspergillusspecies, such asA. fumigatus. Recently developed molecular protocols allow rapid construction of high numbers of fungal deletion mutants, and alternative infection models based on cell culture or invertebrates are widely used for screening such mutants to reduce the number of rodents in animal experiments. To bridge the gap between invertebrate models and mice, we have developed an alternative, low-cost, and easy-to-use infection model forAspergillusspecies based on embryonated eggs. The outcome of infections in the egg model is dose and age dependent and highly reproducible. We show that the age of the embryos affects the susceptibility toA. fumigatusand that increased resistance coincides with altered chemokine production after infection. The progress of disease in the model can be monitored by using egg survival and histology. Based on pathological analyses, we hypothesize that invasion of embryonic membranes and blood vessels leads to embryonic death. Defined deletion mutant strains previously shown to be fully virulent or partially or strongly attenuated in a mouse model of bronchopulmonary aspergillosis showed comparable degrees of attenuation in the egg model. Addition of nutrients restored the reduced virulence of a mutant lacking a biosynthetic gene, and variations of the infectious route can be used to further analyze the role of distinct genes in our model. Our results suggest that embryonated eggs can be a very useful alternative infection model to studyA. fumigatusvirulence and pathogenicity.
Characterization of the Specific Interaction between Sialoadhesin and Sialylated
Campylobacter jejuni
Lipooligosaccharides
Authors: Heikema Astrid P. , Bergman Mathijs P. , Richards Hannah , Crocker Paul R. , Gilbert Michel , Samsom Janneke N. , van Wamel Willem J. B. , Endtz Hubert P. , van Belkum Alex
Published: April 2010

In
Campylobacter jejuni
-induced Guillain-Barré syndrome (GBS), molecular mimicry between
C. jejuni
lipooligosaccharide (LOS) and host gangliosides leads to the production of cross-reactive antibodies directed against the peripheral nerves of the host. Currently, the presence of surface exposed sialylated LOS in
C. jejuni
is the single known bacterial pathogenesis factor associated with the development of GBS. Using a unique, well-characterized strain collection, we demonstrate that GBS-associated
C. jejuni
strains bind preferentially to sialoadhesin (Sn, Siglec-1, or CD169), a sialic acid receptor found on a subset of macrophages. In addition, using a whole-cell enzyme-linked immunosorbent assay (ELISA),
C. jejuni
strains with sialylated LOS bound exclusively to soluble Sn. Mass spectrometry revealed that binding was sialic acid-linkage specific with a preference for α(2,3)-linked sialic acid attached to the terminal galactose of the LOS chain as seen in the gangliosides GD1a, GM1b, and GM3. This molecular interaction was also related to functional consequences as a GBS-associated
C. jejuni
strain that bound Sn in a whole-cell ELISA adhered to surface-expressed Sn of Sn-transfected CHO cells but was unable to adhere to wild-type CHO cells. Moreover, a sialic acid-negative mutant of the same
C. jejuni
strain was unable to bind Sn-transfected CHO cells. This is the first report of the preferential binding of GBS-associated
C. jejuni
strains to the Sn immune receptor (
P
= 0.014). Moreover, because this binding is dependent on sialylated LOS, the main pathogenic factor in GBS progression, the present findings bring us closer to unraveling the mechanisms that lead to formation of cross-reactive antibodies in GBS disease.
Role of High-Mobility Group Box 1 Protein and Poly(ADP-Ribose) Polymerase 1 Degradation inChlamydia trachomatis-Induced Cytopathicity
Authors: Yu Hangxing , Schwarzer Katja , Förster Martin , Kniemeyer Olaf , Forsbach-Birk Vera , Straube Eberhard , Rödel Jürgen
Published: April 2010

As intracellular bacteria, chlamydiae block the apoptotic pathways of their host cells. However, the infection of epithelial cells causes the loss of cell membrane integrity and can result in nonapoptotic death. Normally, cells undergoing necrosis release high-mobility group box 1 protein (HMGB1) that acts as an important proinflammatory mediator. Here, we show that inChlamydia trachomatis-infected HeLa cells HMGB1 is not translocated from the nucleus to the cytosol and not released from injured cells in increased amounts. At 48 h after infection, degradation of HMGB1 was observed. In infected cells, poly(ADP-ribose) polymerase 1 (PARP-1), a DNA repair enzyme that also regulates HMGB1 translocation, was found to be cleaved into fragments that correspond to a necrosislike pattern of PARP-1 degradation. Cell-free cleavage assays and immunoprecipitation using purified proteolytic fractions from infected cells demonstrated that the chlamydial-protease-like activity factor (CPAF) is responsible for the cleavage of both HMGB1 and PARP-1. Proteolytic cleavage of PARP-1 was accompanied by a significant decrease in the enzymatic activity in a time-dependent manner. The loss of PARP-1 function obviously affects the viability ofChlamydia-infected cells because silencing of PARP-1 in uninfected HeLa cells with specific small interfering RNA results in increased cell membrane permeability. Our findings suggest that theChlamydia-specific protease CPAF interferes with necrotic cell death pathways. By the degradation of HMGB1 and PARP-1, the pathogen may have evolved a strategy to reduce the inflammatory response to membrane-damaged cellsin vivo.
Helicobacter pylori
Virulence Factor Genotypes in Children in the United States: Clues about Genotype and Outcome Relationships
Authors: Yamaoka Yoshio , Reddy Rita , Graham David Y.
Published: April 2010

The most common
Helicobacter pylori
genotype among 37 U.S. children was
cagA
positive,
vacA
s1m1, and
oipA
“on” (
n
= 17, 45.9%), followed by
cagA
negative,
vacA
s2m2, and
oipA
“off” (
n
= 8, 21.6%), similar to the pattern in adults.
cagA
positivity was more common in blacks than in whites (i.e., 100% versus 56.5%,
P
= 0.032).
Probiotics and Intestinal Colonization by Vancomycin-Resistant Enterococci in Mice and Humans
Authors: Vidal Magali , Forestier Christiane , Charbonnel Nicolas , Henard Sandrine , Rabaud Christian , Lesens Olivier
Published: April 2010

We investigated the impact of probiotics on the intestinal carriage of vancomycin-resistant enterococci (VRE). Administration of
Lactobacillus rhamnosus
Lcr35 but not
Escherichia coli
Nissle reduced, although not significantly, the density of VRE colonization in a murine model. No effect of Lcr35 was observed in a double-blind placebo randomized study, involving nine patients.
Streptococcus bovis
Meningitis and Hemorrhoids
Authors: Smith Adam Hewitt , Sra Harminder K. , Bawa Sandeep , Stevens Richard
Published: April 2010

We report a case of
Streptococcus bovis
(
Streptococcus gallolyticus
subsp.
pasteurianus
) meningitis, a rare cause of central nervous system (CNS) infection in an adult, and comment on the importance of investigation of the lower gastrointestinal tract to identify a portal of entry in cases of systemic
Streptococcus bovis
infection.
INFLUENCE OF THE CONSTITUTIVE MATERIAL BEHAVIOR MODEL ASSIGNED TO THE ANNULUS FIBROSUS AND THE NUCLEUS PULPOSUS ON THE BIOMECHANICAL PERFORMANCE OF A MODEL OF THE CERVICAL SPINE: A FINITE ELEMENT ANALYSIS STUDY
Authors: LI YUAN , LEWIS GLADIUS
Published: April 2010

One feature of the literature on finite element analysis of models of cervical spine segment(s) is that an assortment of constitutive models has been used for the elastic behavior of the annulus fibrosus (AF) and the nucleus pulposus (NF). The extent to which the model assigned to each of these tissues affects the values of the biomechanical parameters of interest of the model is lacking. This issue was the subject of the present study. We used a three-dimensional solid model of the C4–C6 motion segment units (which comprised the vertebral bodies, the bony posterior elements (transverse processes, pedicles, laminae, spinous processes, and facet joints), the intervertebral discs (IVDs), the endplates, and the five major ligaments) and eight combinations of constitutive models. It was found that (1) the influence of the constitutive material models used depended on the tissue considered, with some, such as the posterior endplate of C5 and the cancellous bone of C6, showing marked sensitivity, while others, such as the cancellous bone of C4 and the cortical bone of C5, were moderately affected; and (2) the biomechanical performance of the spine model is more sensitive to the material behavior model used for the AF than it is to that used for the NF. These results suggest that experimental and computational efforts expended in obtaining the most appropriate constitutive model for the elastic behavior of the two parts of the IVD, in particular the AF, are justified.
TRANSVERSE ISOTROPIC ELASTIC PROPERTIES OF VERTEBRAL TRABECULAR BONE MATRIX MEASURED USING MICROINDENTATION UNDER DRY CONDITIONS (EFFECTS OF AGE, GENDER, AND VERTEBRAL LEVEL)
Authors: WOLFRAM UWE , WILKE HANS-JOACHIM , ZYSSET PHILIPPE K.
Published: April 2010

The mechanical properties of bone extracellular matrix have become of increasing interest for the understanding of vertebral fracture risk. Depth-sensing indentation techniques allow the measurement of directional elastic properties of trabecular bone ex vivo with a high spatial resolution. Transverse isotropic elastic properties of vertebral trabecular bone obtained from two orthogonal directions were investigated using microindentation under dry conditions focusing on the influence of microanatomical location, age, gender, vertebral level, and anatomic direction on these properties. Biopsies were obtained from 104 human vertebrae (T1–L3) with a median age of 65 (21–94) years. Significantly, higher indentation moduli were found for indentations on axial than on transverse cross-sections of trabeculae (p < 0.01). Indentation moduli in the core were 1.05 to 1.12 times higher than in the periphery (p < 0.01). No difference in stiffness could be detected between males and females (p > 0.05) and different ages (p > 0.5). Vertebral level showed a weak correlation (p = 0.073, r2 ≈ 0.17). These results provide insights in the transverse isotropic properties of trabecular bone matrix related to age, gender, microanatomical location, and anatomic direction for a broad spectrum of human vertebrae.
HIGHLY CROSSLINKED POLYETHYLENE: A COMPARATIVE STUDY BETWEEN TWO UHMWPES WITH DISTINCT MOLECULAR WEIGHT
Authors: FERRONI DANIELA , QUAGLINI VIRGINIO , DUBINI PAOLO
Published: April 2010

In the recent years, radiation-induced highly crosslinked polyethylenes have been introduced in arthroplasties as an alternative to conventional ultra high molecular weight polyethylene (UHMWPE) for their superior wear resistance. In the present study, the influence of the molecular weight of the raw on end-user properties of highly crosslinked polyethylenes (HXLPE) is investigated by means of a comparative study between two resins with distinct molecular weights. The main outcomes indicate that the differences in mechanical and wear properties between the row materials disappear after crosslinking; nevertheless the resin with the highest molecular weight is likely to retain a better resistance to short-term oxidation.
MECHANICAL BEHAVIOR UNDER UNCONFINED COMPRESSION LOADINGS OF DENSE FIBRILLAR COLLAGEN MATRICES MIMETIC OF LIVING TISSUES
Authors: RAMTANI SALAH , TAKAHASHI-IÑIGUEZ YOSHIYUKI , HELARY CHRISTOPHE , GEIGER DIDIER , GUILLE MARIE MADELEINE GIRAUD
Published: April 2010

Bio-artificial tissues are being developed as replacements for damaged biologic tissues and their mechanical properties are critical for load-bearing applications. Reconstituted dense three-dimensional (3D) fibrillar collagen matrices are promising materials for tissue engineering, at the light of their interaction with fibroblasts.1,2 The mechanical properties of these fibrillar collagen matrices are now being characterized under unconfined compression loading for various strain rates and collagen concentrations. The data were compared to those obtained in the same conditions with a biological tissue, the rat dermis. The results show a very sensitive behavior to both the displacement rate, typical of biological soft tissues, and the collagen concentration varying between 5 and 40 mg/ml. The link between the mechanical properties and the microscopic structure of the collagen scaffolds show an increasing viscoelastic modulus with respect to the fibril density. It is found that the matrices at 5 mg/ml and the dorsal rat skin (DRS) exhibit similar stress–strain response when submitted to the same external unconfined compression load. Such results highlight the interest of these matrices as potential tissue substitutes.
Engineering rich internet applications with a model-driven approach
Authors: Fraternali Piero , Comai Sara , Bozzon Alessandro , Carughi Giovanni Toffetti
Published: April 2010

Rich Internet Applications (RIAs) have introduced powerful novel functionalities into the Web architecture, borrowed from client-server and desktop applications. The resulting platforms allow designers to improve the user's experience, by exploiting client-side data and computation, bidirectional client-server communication, synchronous and asynchronous events, and rich interface widgets. However, the rapid evolution of RIA technologies challenges the Model-Driven Development methodologies that have been successfully applied in the past decade to traditional Web solutions. This paper illustrates an evolutionary approach for incorporating a wealth of RIA features into an existing Web engineering methodology and notation. The experience demonstrates that it is possible to model RIA application requirements at a high-level using a platform-independent notation, and generate the client-side and server-side code automatically. The resulting approach is evaluated in terms of expressive power, ease of use, and implementability.
Happy Birthday, RDBMS!
Authors: Anthes Gary
Published: April 2010

The relational model of data management, which dates to 1970, still dominates today and influences new paradigms as the field evolves.
Cloud computing and electricity
Authors: Brynjolfsson Erik , Hofmann Paul , Jordan John
Published: April 2010

Assessing the strengths, weaknesses, and general applicability of the computing-as-utility business model.
Enhanced debugging with traces
Authors: Phillips Peter
Published: April 2010

An essential technique used in emulator development is a useful addition to any programmer's toolbox.
Principles of robust timing over the internet
Authors: Ridoux Julien , Veitch Darryl
Published: April 2010

The key to synchronizing clocks over networks is taming delay variability.
Why cloud computing will never be free
Authors: Durkee Dave
Published: April 2010

The competition among cloud providers may drive prices downward, but at what cost?
ACM's 2010 general election
Authors: CACM Staff
Published: April 2010

Meet the candidates who introduce their plans---and stands---for the Association.
Understanding the dynamics of information management costs
Authors: Tallon Paul P.
Published: April 2010

Introduction

Over the past decade, the mountains of data accumulating within firms - expanding at an annual rate of 30-50% and fueled in part by recent legislation such as
SEC Rule 17a-4
mandating the retention of electronic communications (for example, email and instant messaging) in financial services firms for periods of up to three years - has forced information technology (IT) executives to ask how should this data deluge be managed. Intel, whose data warehouse is currently estimated at over 30 petabytes has increased its data storage by an average of 35% annually with the expectation that, if current trends continue, its data center could expand to 165 petabytes by 2014. Yet even as data volumes climb, causing data centers to double in size every other year, an innovation-led drop in annual per-gigabyte storage costs of between 35-45% (see Figure 1) has failed to halt the rise in storage spending.

With organizing and utilizing data now seen as one of the most critical issues facing firms worldwide, IT executives note that non-discretionary IT spending - 25% of which covers information management costs and storage infrastructure, in particular - has now reached a point where strategic IT initiatives are at risk. Hence, CIOs have a pressing need to understand the dynamics of information management costs and their ability to control these costs through carefully chosen policies governing data collection and retention. Knowing how these costs behave, CIOs can continue to support the data needs of their firms without limiting their IT goals.

To begin this process, we examine a tiered information framework that, by considering the value of information, allows CIOs to comprehend the interplay of market forces that shape information costs. Lastly, we review several challenges posed by our framework that future academic research can help to resolve.
Roles of the external IT project manager
Authors: Reich Blaize Horner , Sauer Chris
Published: April 2010

Introduction

IT projects are increasing in scope and complexity, fuelled by intense business competition, ever improving technology, and complex organizational structures and processes. In many cases, companies turn to suppliers of IT services -- systems integrators, consulting project managers, and software solutions providers -- to deliver their tough projects. There are many reasons to look for outside help, including staff shortages, risk reduction, and access to specialized industry or technical knowledge. External project managers are expected not only to successfully deliver against targets, but also to help the organization realize value for money.

To understand how external IT project managers can perform successfully, two questions need to be asked:

• What roles (beyond those of traditional project management) must external project managers fulfil?

• How can they prepare themselves for these roles?

We conducted a set of interviews with leading external project managers (see box for details of the study), focusing on those who manage transformational IT projects.

Their answers take us beyond previous discussions of the need for a project team management role and an external business-facing role.

This article first explains the research study (see the exhibit) and then discusses the roles and skills required of today's external IT project manager. Selected quotes from interviewees are shown as italicized text. It concludes with recommendations about personal and professional development for those entering into external project manager roles.
Confidence-based stopping criteria for active learning for data annotation
Authors: Zhu Jingbo , Wang Huizhen , Hovy Eduard , Ma Matthew
Published: April 2010

The labor-intensive task of labeling data is a serious bottleneck for many supervised learning approaches for natural language processing applications. Active learning aims to reduce the human labeling cost for supervised learning methods. Determining when to stop the active learning process is a very important practical issue in real-world applications. This article addresses the stopping criterion issue of active learning, and presents four simple stopping criteria based on confidence estimation over the unlabeled data pool, includingmaximum uncertainty,overall uncertainty,selected accuracy,andminimum expected errormethods. Further, to obtain a proper threshold for a stopping criterion in a specific task, this article presents a strategy by considering the label change factor to dynamically update the predefined threshold of a stopping criterion during the active learning process. To empirically analyze the effectiveness of each stopping criterion for active learning, we design several comparison experiments on seven real-world datasets for three representative natural language processing applications such as word sense disambiguation, text classification and opinion analysis.
Cloudifying source code repositories
Authors: Siegenthaler Michael , Weatherspoon Hakim
Published: April 2010

Cloud computing provides us with general purpose storage and server hosting platforms at a reasonable price. We explore the possibility of tapping these resources for the purpose of hosting source code repositories for individual projects as well as entire open source communities. An analysis of storage costs is presented, and a complete hosting solution is built and evaluated as a proof-of-concept.
Learning from the past for resolving dilemmas of asynchrony
Authors: Ezhilchelvan Paul , Shrivastava Santosh
Published: April 2010

This paper presents two design approaches to avoid many complications introduced at both user and developer levels by the FLP impossibility. The first approach is appropriate in managed hosting environments, such as datacenters, and involves offering service guarantees with tunable success probabilities and remedial actions in the unlikely scenarios. The second is appropriate in open environments and advocates building fail-signal abstractions for hosting application-level replication.
Analyzing blocking to debug performance problems on multi-core systems
Authors: Fournier Pierre-Marc , Dagenais Michel R.
Published: April 2010

Multi-core systems are rapidly becoming more prevalent. Consequently, developers frequently face performance bugs caused by unexpected interactions between parallel software components. The location of these bugs is difficult to identify with current tools. Indeed, the process exhibiting the slowness may be separated from the root cause of the problem by a blocking chain involving several other processes.

This article introduces a new approach for analyzing blocking on multi-core systems and reports on its implementation in the LTTV Delay Analyzer. It enables developers to quickly understand the dependencies among processes and see how the total elapsed time is divided into its main components. The LTTV Delay Analyzer was used to analyze and rapidly correct complex performance problems, something not possible with the existing tools. The Linux Trace Toolkit, LTTng, is used for most of the instrumentation and the trace recording, allowing the tracing of production systems with great accuracy and minimal impact. This approach uses solely kernel instrumentation and does not require the instrumentation or recompilation of processes. The analysis time is linear with respect to trace size.
Tainting is not pointless
Authors: Dalton Michael , Kannan Hari , Kozyrakis Christos
Published: April 2010

Pointer tainting is a form of Dynamic Information Flow Tracking used primarily to prevent software security attacks such as buffer overflows. Researchers have also applied pointer tainting to malware and virus analysis.

A recent paper by Slowinska and Bos has criticized pointer tainting as a security mechanism, arguing that it is has serious, inherent false positive and false negative defects. We present a rebuttal that addresses the confusion due to the two uses of pointer tainting in security literature. We clarify that many of the arguments against pointer tainting apply only to its use as a malware and virus analysis platform, but do not apply to the application of pointer tainting to memory corruption protection. Hence, we argue that pointer tainting remains a useful and promising technique for robust protection against memory corruption attacks.
Highlights from ACM SIGSPATIAL GIS 2009
Authors: Mokbel Mohamed F. , Scheuermann Peter
Published: April 2010

ACM GIS 2009 was the seventeenth event of a series of conferences, symposia, and workshops that began in 1993 with the mission of bringing together researchers, developers, users, and practitioners carrying out research and development of novel systems based on geo-spatial data and knowledge. The conference fosters interdisciplinary discussions and research in all aspects of Geographic Information Systems and Science (GIS) and provides a forum for original research contributions covering all conceptual, design, and implementation aspects of GIS ranging from applications, user interface considerations, and visualization to storage management, indexing, and algorithmic issues.
SPRINGL 2009 Workshop Report
Authors: Damiani Maria Luisa , Saygin Yucel
Published: April 2010

The second International Workshop on Security and Privacy in GIS and LBS (SPRINGL 2009) was held on 3rd November 2009 in Seattle, Washington, in conjunction with the 17th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems. The mission of the SPRINGL Workshop series is to provide a forum for researchers and practitioners from computer science and other disciplines working in the area of spatio-temporal data security and location privacy in the context of geospatial and mobile applications. Eight papers were selected for presentation and inclusion into the workshop proceedings. The workshop program also included two invited talks by Mohamed Mokbel (University of Minnesota) and Walid Aref (Purdue University), and a panel moderated by Yucel Saygin.
Welcome to SIGSPATIAL China
Authors: Xie Xing
Published: April 2010

Location-based services are becoming a very hot topic in China. In order to promote ACM SIGSPATIAL and the corresponding research area in China, and encourage collaboration between SIGSPATIAL researchers in China and researchers worldwide, in late September 2009, Wuhan University, Renmin University and Microsoft Research Asia worked together to submit an application for establishing the ACM SIGSPATIAL China Chapter. The application was approved by the SIGSPATIAL Executive Committee in late October 2009.
Possible Association between Th1 Immune Polarization and Epithelial Permeability with Toll-Like Receptors 2 Dysfunction in the Pathogenesis of the Recurrent Aphthous Ulceration
Authors: Barros Fabiana M. , Lotufo Mônica A. , Andrade Priscila M. , França Cristiane M. , Borra Ricardo C.
Published: April 2010

Recurrent Aphthous Ulceration (RAU) is a chronic oral inflammatory disease that affects approximately 25% of the general population. The etiology of the disease is unknown; however, factors that favor the onset of RAU have been correlated with a Th1 immune polarization, while factors that reduce RAU episodes have been associated with down regulation of immune reaction or stimulation of the peripheral tolerance. In this context, the integrity of the epithelial barrier is also fundamental for the prevention of the disease and conditions that augment its permeability or produce disruption are considered potential triggers. The key factor responsible for increased susceptibility is unclear, though a deficiency of Toll-like receptor (TLR) activity seems to be a good candidate. TLRs are a group of membrane proteins that recognize conserved molecules derived from bacterial, virus, fungal, or host tissues. Particularly, the TLR2 is involved in both immune regulation and control of epithelial barrier integrity. Thus, based on literature review, we showed evidences that correlate the TLR2 dysfunction and the diverse predisposing factors with the elements considered critical for disease pathogenesis: the Th1 immune reaction and the increased epithelial permeability.
Ghrelin in Diabetes and Metabolic Syndrome
Authors: Pulkkinen Leena , Ukkola Olavi , Kolehmainen Marjukka , Uusitupa Matti
Published: April 2010

Metabolic syndrome is a cluster of related risk factors for cardiovascular disease, type 2 diabetes and liver disease. Obesity, which has become a global public health problem, is one of the major risk factors for development of metabolic syndrome and type 2 diabetes. Obesity is a complex disease, caused by the interplay between environmental and genetic factors. Ghrelin is one of the circulating peptides, which stimulates appetite and regulates energy balance, and thus is one of the candidate genes for obesity and T2DM. During the last years both basic research and genetic association studies have revealed association between the ghrelin gene and obesity, metabolic syndrome or type 2 diabetes
Increasing a Robust Antigen-Specific Cytotoxic T Lymphocyte Response by FMDV DNA Vaccination with IL-9 Expressing Construct
Authors: Zou Qiang , Wu Bing , He Xiaodan , Zhang Yizhi , Kang Youmin , Jin Jin , Xu Hanqian , Liu Hu , Wang Bin
Published: April 2010

Various chemokines and cytokines as adjuvants can be used to improve efficacy of DNA vaccination. In this study, we sought to investigate if a DNA construct expressing IL-9 (designed as proV-IL9) as a molecular adjuvant enhance antigen specific immune responses elicited by the pcD-VP1 DNA vaccination. Mice immunized with pcD-VP1 combined with proV-IL9 developed a strong humoral response. In addition, the coinoculation induced significant higher level of antigen-specific cell proliferation and cytotoxic response. This agreed well with higher expression level of IFN-γand perforin in CD8+T cells, but not with IL-17 in these T cells. The results indicate that IL-9 induces the development of IFN-γ-producing CD8+T cells (Tc1), but not the IL-17-producing CD8+T cells (Tc17). Up-regulated expressions of BCL-2 and BCL-XL were exhibited in these Tc1 cells, suggesting that IL-9 may trigger antiapoptosis mechanism in these cells. Together, these results demonstrated that IL-9 used as molecular adjuvant could enhance the immunogenicity of DNA vaccination, in augmenting humoral and cellular responses and particularly promoting Tc1 activations. Thus, the IL-9 may be utilized as a potent Tc1 adjuvant for DNA vaccines.
Advanced Clinical Usefulness of Ultrasonography for Diseases in Oral and Maxillofacial Regions
Authors: Wakasugi-Sato Nao , Kodama Masaaki , Matsuo Kou , Yamamoto Noriaki , Oda Masafumi , Ishikawa Ayataka , Tanaka Tatsurou , Seta Yuji , Habu Manabu , Kokuryo Shinya , Ichimiya Hisashi , Miyamoto Ikuya , Kito Shinji , Matsumoto-Takeda Shinobu , Wakasugi Tetsuro , Yamashita Yoshihiro , Yoshioka Izumi , Takahashi Tetsu , Tominaga Kazuhiro , Morimoto Yasuhiro
Published: April 2010

Various kinds of diseases may be found in the oral and maxillofacial regions and various modalities may be applied for their diagnosis, including intra-oral radiography, panoramic radiography, ultrasonography, computed tomography, magnetic resonance imaging, and nuclear medicine methods such as positron emission tomography. Of these modalities, ultrasound imaging is easy to use for the detection of noninvasive and soft tissue-related diseases. Doppler ultrasound images taken in the B-mode can provide vascular information associated with the morphology of soft tissues. Thus, ultrasound imaging plays an important role in confirming the diagnosis of many kinds of diseases in such oral and maxillofacial regions as the tongue, lymph nodes, salivary glands, and masticatory muscles. In the present article, we introduce three new applications of ultrasonography: guided fine-needle aspiration, measurement of tongue cancer thickness, and diagnosis of metastasis to cervical lymph nodes.
Simultaneous Determination of Copper, Lead, and Cadmium at Hexagonal Mesoporous Silica Immobilized Quercetin Modified Carbon Paste Electrode
Authors: Xia Fangquan , Zhang Xin , Zhou Changli , Sun Danzi , Dong Yanmin , Liu Zhen
Published: April 2010

A new method was developed for simultaneous determination of copper, lead, and cadmium, based on their voltammetric response at a carbon paste electrode modified with hexagonal mesoporous silica (HMS) immobilized quercetin (HMS-Qu/CPE). Compared with quercetin modified carbon paste electrode (Qu/CPE) and quercetin ionic liquid modified carbon paste electrode (Qu-IL/CPE), the HMS-Qu/CPE exhibited improved selectivity and high sensitivity toward the detection of copper, lead, and cadmium. The properties of the HMS-Qu/CPE in 0.1 M HCOONa-HCl buffer solution (pH4.7) were investigated by adsorptive stripping voltammetry (ASV) and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of copper, lead, and cadmium at the modified electrodes and factors affecting the preconcentration procedures were also investigated. Detection limits of 5.0, 0.8, 1.0 nM for copper, lead, and cadmium were obtained, respectively. The method is simple, fast, sensitive, and selective, and is successfully applied to soil sample.