bluuebunny/crossref_metadata_2025 huggingface dataset:
Extension of the FLASH Method to Semitransparent Polymer Foams
Authors: Coquard R. , Randrianalisoa J. , Lallich S. , Baillis D.
Published: September 2011

The classical photo-thermal FLASH method is a very practicable method for measurement of the conductive properties of solid materials due to its simplicity, rapidity, and to the limited size of the samples required. It has been applied successfully to a wide variety of materials. However, it is theoretically restricted to purely conductive media. Notably, it could, strictly speaking, not be used to measure the equivalent conductivity of low-density thermal insulators since a significant part of the heat transfer is due to the propagation of thermal radiation. This constitutes a major drawback of the method. Therefore, the present study investigates the possibility to extend the method to this kind of materials by estimating the errors made on the equivalent conductivity when the classical FLASH method is used. To this aim, FLASH experiments have been conducted at different temperatures on several low-density polymer foams whose radiative properties have been estimated from spectrometric measurements. By applying a least-square fit-method associated with a numerical simulation of the 1D coupled heat transfer, we managed to identify the phonic conductivities of the samples and to compute their equivalent conductivities. These values have been compared with the thermal conductivities obtained from classical FLASH method, i.e., assuming that the thermal transfer occurs only by heat conduction. It appears that the discrepancies between the conductivities stemming from the classical FLASH method and the equivalent conductivities computed are quite negligible at ambient temperature even for foams with very low densities. This demonstrates the applicability of the classical FLASH method to this type of materials for building applications. This conclusion is likely to interest foam manufacturers in view of reducing the time required for an accurate measurement of the insulating performances. On the other hand, at elevated temperatures, the errors become significant so that the method could not be considered satisfactory.
Enhancement of Surface Quality and Study on Material Removal Mechanism in Micro Ultrasonic Machining
Authors: Zarepour Hamid , Yeo Swee-Hock
Published: September 2011

Surface integrity, mechanical deformation, and thermal deformation are among the crucial error generation factors in tool-based micromachining the influence of which should be minimized. As a micromachining process, micro ultrasonic machining (micro-USM) must satisfy the above considerations. In micro-USM, material is removed by fine and free abrasive particles inside a fluid; hence, there is no direct contact between micro-tool and the workpiece. Furthermore, no thermal damage is induced into the machined surface. Therefore, this process can satisfy the requirements of minimum mechanical and thermal deformation as a tool-based micromachining process. However, usually a rather course surface with subsurface microcracks is generated by USM processes. As such, study on surface characteristics and improvement of surface quality in micro-USM is considered necessary in order to introduce this process as a mature micromachining process. In this paper, the effect of various process parameters on surface quality in micro-USM is studied. The parameters include static load, vibration amplitude, abrasive particle size, and slurry concentration. Machining experiments were conducted using a self-developed micro-USM system with the method of workpiece vibration and using a precision static load measurement system with high sampling rate. An average surface roughness as small as 24 nm was achieved through the investigations on machined surface quality which has not been reported in micro-USM process using the workpiece vibration method. Moreover, the effect of process parameters on dominant removal mechanisms is investigated.
Sol-Gel Synthesis and Magnetic, Optical and Impedance Behaviour of Strontium Ferrite Powder
Authors: Jaiswal Shivendra Kumar , Kumar Jitendra
Published: September 2011

An attempt has been made to synthesize SrFeO3-δ powder by sol-gel process involving oxalate formation, its digestion for 4h, drying at 150°C for 24h, and decomposition at 800°C for 10h. The resulting powder is shown to a) exhibit a single phase with a perovskite-type cubic structure and lattice parameter a = 3.862±0.002A˚, b) contain irregular shape particles, and c) display optical absorption peaks corresponding to charge transfer from oxygen to iron (3.73 and 3.41eV), t2g to eg transition of Fe3+ (1.57eV), and crystal field (3d-3d) charge transfer of Fe3+ (1.25eV). Impedance over a wide frequency range of 20Hz-2MHz at 118–318K has contributions from two parallel ‘RC’ circuits belonging to bulk and grain boundaries with the later displaying significant space charge polarization. The relaxation time of polarization follows an Arrhenius behaviour (τ = τo exp[Ea/kBT]) with τo as ∼10−8s and activation energy Ea as ∼50meV. Further, the sample having magnetic character with transition temperature as 853K, coercivity (Hc) = 3748Oe and magnetization 0.09 μB per iron atom (at 17kOe). The zero field cooled and field cooled magnetization versus temperature data in conjunction with constricted hysteresis loops near the origin suggest core-shell morphology for the particles, core being antiferromagnetic with net uncompensated moment and shell conforming to disordered disposition of spins.
Survey of Courses on Renewable Energy Manufacturing at American Universities
Authors: Cong W. L. , Pei Z. J.
Published: September 2011

Both U.S. and world economies have long depended on fossil energy (coal, oil, and natural gas). Supplies of fossil energy are expected to decline in the future and become more expensive. Meanwhile, their use contributes to the accumulation of greenhouse gas in the atmosphere. Therefore, an urgent need exists for renewable energy sources. In order to enhance the global competitiveness of the U.S. in renewable energy manufacturing, there is a dramatic need for a skilled workforce that has been trained in this field. A survey on renewable energy courses at more than 100 U.S. universities has been conducted. It is found that manufacturing aspects of all forms of renewable energy are not emphasized, and there are no sophomore-level courses that cover manufacturing of all forms of renewable energy at these universities.
Development of a Condition Based Maintenance Program for a CNC Machine: Part 1—Signal Acquisition, Processing, and Network Communication
Authors: Werner Andrew , Mehta Parikshit , Mears Laine
Published: September 2011

Condition based maintenance (CBM) of machine tools is an important maintenance strategy to invoke for a manufacturing company to run as lean as possible. CBM does this by indicating, in advance, the failure of the machine tool components or system, thus reducing the machine downtime. In this paper, the development of such a system is sought. A background review of the need and structure of such a system has been provided as well as the design considerations for the system are discussed. Having those considerations as the target requirements for a CBM system, discussion of a demonstrative system is presented, being implemented on an OKUMA LB 3000EX CNC lathe. Leveraging the Open Architecture Control (OAC) technology built into OKUMA CNC systems, the proposed system shall enhance machine monitoring by integrating the internal and external sensors aboard the machine tool. This work lays the foundation for the framework of a proposed CBM system. Coolant temperatures and spindle vibration signals are acquired and processed using a high speed data acquisition system. Towards the end of the paper, descriptions of how to best use this data and integrate it with the machine tool CNC system have been provided.
Multi-Objective Optimization for the Micro-Milling Process With Adaptive Data Modeling
Authors: Liu Xinyu , Zhu Weihang , Zaloom Victor
Published: September 2011

This paper presents a multi-objective optimization study for the micro-milling process with adaptive data modeling based on the process simulation. A micro-milling machining process model was developed and verified through our previous study. Based on the model, a set of simulation data was generated from a factorial design. The data was converted into a surrogate model with adaptive data modeling method. The model has three input variables: axial depth of cut, feed rate and spindle speed. It has two conflictive objectives: minimization of surface location error (which affects surface accuracy) and minimization of total tooling cost. The surrogate model is used in a multi-objective optimization study to obtain the Pareto optimal sets of machining parameters. The visual display of the non-dominated solution frontier allows an engineer to select a preferred machining parameter in order to get a lowest cost solution given the requirement from tolerance and accuracy. The contribution of this study is to provide a streamlined methodology to identify the preferred best machining parameters for micro-milling.
Model Based Prediction and Control of Machining Deflection Error in Turning Slender Bars
Authors: Mehta Parikshit , Mears Laine
Published: September 2011

Model based control of machining processes is aimed at improving the performance of CNC systems by using the knowledge of machining process to reduce cost, improving machining accuracy and improving overall productivity. In this paper, real time control of the machining process to maintain dimensional quality when turning a slender bar is addressed. The goal is to actively control the machining feed rate to maintain constant and predicable deflection through a combined force-stiffness model integrated to the process controller. A brief review is presented on manufacturing process models, process monitoring, and model based control strategies such as Model Predictive Control (MPC). The main objective of this paper is to outline a method for deploying such models to process control. To demonstrate this, model of the deflection of the workpiece under tool cutting forces is developed. Unknown process parameters have been calculated using series of FEA simulations and verified with basic experimental data. A simple but effective control strategy has been formulated and simulated. In the initial results, the diameter of bar is maintained within 1.04% error with controller as opposed to up to 4% error without controller. Ultimately, the goal is to deploy such control strategies in the industrial control system. With the continual development in physical understanding of machining processes and affordable computing technology (both software and hardware) coupled with Open Architecture Control (OAC) applied to CNC machine tools, such approaches are now computationally feasible. This will be an enabling factor to deploy model based control in an industrial environment. The last section discusses the proposed hardware architecture to achieve this. The paper concludes with a brief plan for the future work and a summary.
Towards Mass-Scale Micro-Assembly Systems Using Magnetotactic Bacteria
Authors: Martel Sylvain , Mohammadi Mahmood
Published: September 2011

Magnetotactic bacteria (MTB) can be used in a coordinated fashion to assemble micro-objects in an orderly manner. To perform micro-assembly tasks, magnetotaxis-based control is used where a directional magnetic field is generated to induce a torque on an embedded chain of membrane-based magnetic nanoparticles (MNP) named magnetosomes. Such chain acts like a nano-compass or a nano-steering system embedded in each bacterium. Such magnetotaxis-based control is then used to orient the MTB in such a way that the laminar flow created by their flagella bundles provides a displacement force on the micro-objects being assembled. Since the force is generated by the bacteria, relatively large micro-objects can be moved with no requirement for electrical energy except for a relatively small value required for inducing a directional torque on the chain of magnetosomes in the cells. Because the energy required to generate the directional torque is independent on the population of MTB being involved but the displacement force can be scaled up with the use of a larger swarm while the total workspace would typically be at microscale dimensions, the energy required for the coils configuration around such workspace and responsible for generating the directional torque can be reduced further to a very low level and hence, makes the implementation of mass-scale bacterial micro-assembly systems, a viable approach. Based on these findings, we propose a corresponding mass-scale system based on many workspaces, each relying on a swarm of MTB to perform micro-assembly tasks in parallel.
Effect of Element Types on Failure Prediction Using a Stress-Based Forming Limit Curve
Authors: Hasan Raed Z. , Kinsey Brad L. , Tsukrov Igor
Published: September 2011

Strain-based forming limit diagrams (FLDs) are the traditional tool used to characterize the formability of materials for sheet metal forming processes. However, this failure criterion exhibits a significant strain path dependence. Alternatively, stress-based forming limit diagrams (FLDs) have been proposed and shown to be less sensitive to the deformation path. The stress-based failure criterion can be conveniently implemented in numerical simulations. However, for reliable numerical modeling, the sensitivity of the models to the selection of discretization parameters, in particular, the element type must be assessed. In this paper, Marciniak tests have been numerically simulated to investigate failure prediction using three different element types (shell, solid and solid-shell). Seven different specimen geometries were modeled in order to vary the loading paths. The results show that despite differences in stress calculation assumptions, shell, solid and solid-shell elements do not provide differences in failure prediction when a stress-based failure criterion is used.
An Experimental Comparison of Two Pelleting Methods for Cellulosic Ethanol Manufacturing
Authors: Zhang Qi , Zhang Pengfei , Pei Z. J. , Wilson Jonathan , McKinney Leland , Pritchett Graham
Published: September 2011

Ethanol produced from cellulosic biomass is an alternative to petroleum-based transportation fuels. However, manufacturing costs of cellulosic ethanol are too high to be competitive. Low density of cellulosic feedstocks increases their handling and transportation costs, contributing to high overall costs of cellulosic ethanol manufacturing. Pelleting can increase density of cellulosic feedstocks, reduce transportation and storage costs, and make cellulosic ethanol production more competitive. UV-A (ultrasonic vibration-assisted) pelleting is a new pelleting method (available only in lab scale now). Preliminary research showed that UV-A pelleting could significantly increase pellet density and pellet durability but it has never been compared with other pelleting methods (e.g., using an extruder, a briquetting press or a ring-die pelleting). The objectives of this research are to compare UV-A pelleting with ring-die pelleting in terms of pellet density, pellet durability, energy consumptions of pelleting. The results will be useful to find a better pelleting method for cellulosic ethanol manufacturing.
Estimation of Milling Tool Temperature Considering Coolant and Wear
Authors: Kuo Hsin-Yu , Meyer Kevin , Lindle Roger , Ni Jun
Published: September 2011

This paper presents a novel technique to estimate the temperature distribution of a milling tool during machining. In this study, heat generation during the machining process is estimated using cutting forces. We consider the heat to be time-dependent heat flux into the tool. In the proposed model, we discretize each rake face on a mill into several elements; each experiences time-dependent heat flux. Second, we approximate the time-dependent heat flux as several constant heat input starts at different time. Finally, we sum the temperature rise from each heat flux to obtain the overall temperature change. A similar concept is applied on the flank surface, where the flank wear area is modeled as an additional heat generation zone. Experimental results are presented to validate the developed model.
Numerical Modeling of Transport Phenomena and Dendritic Growth in Laser Conduction Welding of 304 Stainless Steel
Authors: Tan Wenda , Bailey Neil S. , Shin Yung C.
Published: September 2011

A multi-scale model is developed to investigate the heat/mass transport and dendrite growth in laser spot conduction welding. A macro-scale transient model of heat transport and fluid flow is built to study the evolution of temperature and velocity field of the molten pool. The molten pool geometry and other solidification parameters are calculated, and the predicted pool geometry matches well with experimental result. On the micro-scale level, the dendritic growth of 304 stainless steel is simulated by a novel model that has coupled the Cellular Automata (CA) and Phase Field (PF) methods. The epitaxial growth is accurately identified by defining both the grain density and dendrite arm density at the fusion line. By applying the macro-scale thermal history onto the micro-scale calculation domain, the microstructure evolution of the entire molten pool is simulated. The predicted microstructure achieves a good quantitative agreement with the experimental results.
Prediction on Die Structure Performance During Advanced High-Strength Steel Sheet Metal Stamping With Non-Rigid Tooling Definition
Authors: Xu Dong-kai , Chen Jun , Li Xi-feng , Tang Yu-cheng , Zhang Gui-bao
Published: September 2011

Die structure behavior and its stability are playing more important roles in stamping of advanced high-strength steel (AHSS) sheet metals since the die structure has to maintain steady forming conditions when larger forming load is generated and applied on the die components. Before the workshop try-out, the virtual testing tool is necessary to assure the stamping die design safety. In this paper, a reliable and efficient method to forecast the die structure performance using an updated load mapping algorithm was proposed to verify the stamping die structure design. Furthermore, an improved method for sheet metal forming modeling with non-rigid tooling definition was also presented to enhance the prediction accuracy. In order to validate the proposed method, a step-shaped-bottom cup drawing die was developed and a data collection system was also adopted to measure the strain/stress evolution at specified locations and to reveal the phenomenon of tooling deflection during the AHSS sheet metal drawing process. The comparison between experimental results and prediction demonstrated very good correlation, and the revised method is more accurate and efficient and is expected to be used to verify the industrial AHSS stamping die designs and support the further research on die structure optimization.
Dielectric and Piezoelectric Ceramics for High Temperature Applications
Authors: Raengthon Natthaphon , Nikkel Jason , Ansell Troy , Cann David P.
Published: September 2011

Perovskite materials have been widely embedded in many consumer and industrial electronics, both for capacitor applications in the case of dielectric materials, and for actuator, transducer and sensor applications in the case of piezoelectric materials. Functional devices used in high temperature environments, such as deep oil well instrumentation, geothermal exploration, and devices for aerospace applications require the persistence of materials’ properties at high temperatures. In this paper, high potential capacitor and piezoelectric ceramics for high temperature applications are presented. High dielectric constant (K) materials based on 0.8BaTiO3 – 0.2Bi(Zn1/2Ti1/2)O3 solid solutions have been shown to have superior properties for high temperature capacitor applications. Studies of the temperature dependence of the dielectric properties have shown that the composition with Ba vacancies exhibits a high relative permittivity (εr > 1150) and a low dielectric loss (tan δ < 0.05) that persist up to a temperature of 460 °C. This composition also shows a high resistivity in excess of 7.0 × 1010 Ω-cm which remains unchanged up to a temperature of 270 °C as well as a large RC time constant (RC > 20 s). In the case of high temperature piezoelectric ceramics, solid solutions of PbTiO3 – BiScO3 – Bi(M1/2Ti1/2)O3 ternary systems were studied, where M is Mg and Zn. The ratio of BiScO3 to Bi(M1/2Ti1/2)O3 was kept at 1:1, while the concentration of PbTiO3 was varied. X-ray diffraction patterns showed that tetragonal symmetry was observed in compositions which contain a high concentration of PbTiO3 (> 60 mol%). Evidence of a morphotropic phase boundary (MPB) was observed with compositions containing PbTiO3 in the range of 52–56 mol%. At 70 mol% PbTiO3 compositions, high Curie temperatures (TC) of 490 °C and 533 °C were observed for compositions containing Mg and Zn, respectively.
A Bio-Inspired Framework for a Self-Healing Assembly System
Authors: Wells Lee J. , Camelio Jaime A. , Zapata Giovannina
Published: September 2011

Statistical process monitoring and control has been popularized throughout the manufacturing industry as well as various other industries interested in improving product quality and reducing costs. Advances in this field have focused primarily on more efficient ways for diagnosing faults, reducing variation, developing robust design techniques, and increasing sensor capabilities. System level advances are largely dependent on the introduction of new techniques in the listed areas. A unique system level quality control approach is introduced in this paper as a means to integrate rapidly advancing computing technology and analysis methods in manufacturing systems. Inspired by biological systems, the developed framework utilizes immunological principles as a means of developing self-healing algorithms and techniques for manufacturing assembly systems. The principles and techniques attained through this bio-mimicking approach will be used for autonomous monitoring, detection, diagnosis, prognosis, and control of station and system level faults, contrary to traditional systems that largely rely on final product measurements and expert analysis to eliminate process faults.
An Investigation on Deformation-Based Micro Surface Texturing
Authors: Zhou Rui , Cao Jian , Ehmann Kornel , Xu Chun
Published: September 2011

Micro surface textures have various applications, such as friction/wear reduction and bacteria sterilization. Deformation-based micro surface texturing has the potential of economically creating micro surface textures over a large surface area. A novel desktop micro surface texturing system is proposed for efficiently and economically fabricating micro channels on the surface of thin sheet material for micro fluid and friction/wear reduction applications. Both experimental and numerical studies were employed to analyze the problems of the flatness of the textured sheet, the uniform of the channel depth and pile-ups built up during the micro surface texturing process. The results demonstrated a clear relationship between relative velocity of the upper and lower rolls and the flatness of the textured sheet and the final profile of the micro channels.
Geometric Modeling and Analysis of Single Point Cutting Tools With Generic Profile
Authors: Sambhav Kumar , Tandon Puneet , Dhande Sanjay G.
Published: September 2011

The presented work models the geometry of Single Point Cutting Tools (SPCTs) with generic profile. Presently few standard shapes of SPCTs defined in terms of projective geometry are being employed while there is a need to design free-form tools to efficiently machine free-form surfaces with few passes and chosen range of cutting angles. To be able to produce SPCT face and flanks with generic shapes through grinding, a comprehensive geometric model of the tool in terms of the varying grinding angles and the ground depths is required which helps design the tool with arbitrarily chosen tool angles. The surface modeling begins with the creation of a tool blank model followed by transformation of unbounded planes to get the cutting tool surfaces. The intersection of these surfaces with the blank gives the complete model of the tool. Having created the geometric model in two generations of generalization, the paper presents the methodology to obtain the conventional tool angles from the generic model. An illustration of the model has been provided showing variation of tool angles along the cutting edge with changing grinding parameters. When the geometric model is not to be related to the grinding parameters, the SPCT can be modeled as a composite NURBS surface which has been presented towards the end of the work.
Cutting Mechanics of High Speed Dry Machining of Magnesium-Calcium Biomedical Alloy Using Internal State Variable Plasticity Model
Authors: Salahshoor M. , Guo Y. B.
Published: September 2011

Magnesium-Calcium (MgCa) alloys have become attractive orthopedic biomaterials due to their biodegradability, biocompatibility, and congruent mechanical properties with bone tissues. However, process mechanics of machining biomedical MgCa alloys is poorly understood. Mechanical properties of the biomedical magnesium alloy at high strain rates and large strains are determined by using the split-Hopkinson pressure bar testing method. Internal state variable (ISV) plasticity model is implemented to understand the dynamic material behavior under cutting conditions. A finite element simulation model has been developed to study the chip formation during high speed dry cutting of MgCa0.8 (wt %) alloy. Continuous chip formation predicted by the FE simulation is verified by high speed dry face milling of MgCa0.8 using polycrystalline diamond (PCD) inserts. Chip ignition is known as the most hazardous aspect of machining Mg alloys. The predicted temperature distributions may well explain the reason for machining safety of high-speed dry cutting of MgCa0.8 alloy.
Wetting properties induced in nano-composite POSS-MA polymer films by atomic layer deposited oxides
Authors: Vasquez Kyle A. , Vincent-Johnson Anita J. , Christopher Hughes W. , Augustine Brian H. , Lee Kyoungmi , Parsons Gregory N. , Scarel Giovanna
Published: September 2011

Due to their unique properties, nano-composite polyhedral oligomeric silsequioxane (POSS) copolymer films are attractive for various applications. Here we show that their natural hydrophobic character can become hydrophilic when the films are modified by a thin oxide layer, up to 8 nm thick, prepared using atomic layer deposition. A proper choice of the deposition temperature and thickness of the oxide layer are required to achieve this goal. Unlike other polymeric systems, a marked transition to a hydrophilic state is observed with oxide layers deposited at increasing temperatures up to the glass transition temperature (∼110 °C) of the POSS copolymer film. The hydrophilic state is monitored through the water contact angle of the POSS film. Infrared absorbance spectra indicate that, in hydrophilic samples, the integral of peaks corresponding to surface Al–O (hydrophilic) is significantly larger than that of peaks linked to hydrophobic species.
Stress Fractures in DNA
Authors: Wong Wei
Published: September 2011

Prolonged adrenergic stimulation results in DNA damage through a β-arrestin1–dependent pathway.
Noncovalent Complexes of an Inactive Mutant of CTX-M-9 with the Substrate Piperacillin and the Corresponding Product
Authors: Leyssene David , Delmas Julien , Robin Frédéric , Cougnoux Antony , Gibold Lucie , Bonnet Richard
Published: September 2011

We determined the crystal structure of an inactive Ser70Gly mutant of CTX-M-9 in complex with the bulky penicillin piperacillin at precovalent and posthydrolytic stages in the catalytic process. The structures obtained at high resolution were compared with the corresponding structures for the small penicillin benzylpenicillin and the bulky cephalosporin cefotaxime. The findings highlight the key role of the configuration of the carbon adjacent to the acylamino group of the side chain of β-lactams in the precovalent recognition of substrates.
Prospective Multicenter Study of the Epidemiology, Molecular Identification, and Antifungal Susceptibility of Candida parapsilosis, Candida orthopsilosis, and Candida metapsilosis Isolated from Patients with Candidemia
Authors: Cantón Emilia , Pemán Javier , Quindós Guillermo , Eraso Elena , Miranda-Zapico Ilargi , Álvarez María , Merino Paloma , Campos-Herrero Isolina , Marco Francesc , de la Pedrosa Elia Gomez G. , Yagüe Genoveva , Guna Remedios , Rubio Carmen , Miranda Consuelo , Pazos Carmen , Velasco David ,   the FUNGEMYCA Study Group
Published: September 2011

A 13-month prospective multicenter study including 44 hospitals was carried out to evaluate the epidemiology of
Candida parapsilosis
complex candidemia in Spain. Susceptibility to amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole, posaconazole, anidulafungin, caspofungin, and micafungin was tested by the microdilution colorimetric method. A total of 364
C. parapsilosis
complex isolates were identified by molecular methods:
C. parapsilosis
(90.7%),
Candida orthopsilosis
(8.2%), and
Candida metapsilosis
(1.1%). Most candidemias (
C. parapsilosis
, 76.4%;
C. orthopsilosis
, 70.0%;
C. metapsilosis
, 100%) were observed in adults. No
C. orthopsilosis
or
C. metapsilosis
candidemias occurred in neonates.
C. parapsilosis
was most frequent in adult intensive care unit (28.8%), surgery (20.9%), and internal medicine (19.7%) departments; and
C. orthopsilosis
was most frequent in hematology (28.6%), pediatrics (12.0%), and neonatology (11.5%) departments. The geographic distribution of
C. orthopsilosis
and
C. metapsilosis
was not uniform. According to CLSI clinical breakpoints, all
C. orthopsilosis
and
C. metapsilosis
isolates were susceptible to the nine agents tested. Resistance (MICs > 1 mg/liter) was observed only in
C. parapsilosis
: amphotericin B, posaconazole, itraconazole, and caspofungin (0.3% each), anidulafungin (1.9%), and micafungin (2.5%). Applying the new species-specific fluconazole and echinocandin breakpoints, the rates of resistance to fluconazole for
C. parapsilosis
and
C. orthopsilosis
increased to 4.8% and 0.3%, respectively; conversely, for
C. parapsilosis
they shifted from 1.9 to 0.6% (anidulafungin) and from 2.5 to 0.6% (micafungin). Our study confirms the different prevalence of
C. parapsilosis
complex candidemia among age groups: neither
C. orthopsilosis
nor
C. metapsilosis
was isolated from neonates; interestingly,
C. metapsilosis
was isolated only from adults and the elderly. The disparity in antifungal susceptibility among species could be important for therapy.
Genetic Features of CTX-M-15-Producing Acinetobacter baumannii from Haiti
Authors: Potron Anaïs , Munoz-Price L. Silvia , Nordmann Patrice , Cleary Timothy , Poirel Laurent
Published: September 2011

Acinetobacter baumannii
isolates T23, W35, and H1 were isolated from three patients who had been injured in the Haiti earthquake in January 2010. Those isolates, corresponding to two distinct clones, were identified as extended-spectrum β-lactamase (ESBL) producers and found to be
bla
CTX-M-15
-positive. That ESBL gene was associated with IS
Ecp1
, involved in its acquisition by a one-ended transposition mechanism. In all isolates, the IS
Ecp1-bla
CTX-M-15
compound transposon was apparently chromosomally located.
Effect of Rifampin on Production of Inflammatory Mediators in HepG2 Liver Epithelial Cells
Authors: Yuhas Yael , Berent Eva , Ashkenazi Shai
Published: September 2011

Rifampin, a potent antibacterial agent, is one of the main drugs used in the treatment of mycobacterial infections. Hepatotoxicity is a well-documented adverse event. The aim of this study was to investigate the effect of rifampin on the production of inflammatory mediators in human epithelial HepG2 liver cells in the absence or presence of proinflammatory cytokines. Incubation of HepG2 cells with a cytokine mix plus rifampin was associated with a significant dose-dependent increase in the production of nitric oxide compared to incubation with the cytokine mix alone (P< 0.05) as well as with an increase in inducible nitric oxide synthase protein and mRNA expression. Rifampin significantly increased the secretion of interleukin 8 (IL-8) in both untreated cells (P< 0.001) and cytokine-treated cells (P< 0.006). An array screening assay revealed that rifampin stimulated the production of IL-1β and gamma interferon-induced protein-10 (IP-10) in untreated cells and increased the secretion of RANTES in cytokine-treated cells. Together, these results indicate that rifampin may exert proinflammatory effects on liver cells.
Candida albicans Cell Wall Glycosylation May Be Indirectly Required for Activation of Epithelial Cell Proinflammatory Responses
Authors: Murciano Celia , Moyes David L. , Runglall Manohursingh , Islam Ayesha , Mille Celine , Fradin Chantal , Poulain Daniel , Gow Neil A. R. , Naglik Julian R.
Published: September 2011

Oral epithelial cells discriminate between the yeast and hyphal forms of
Candida albicans
via the mitogen-activated protein kinase (MAPK) signaling pathway. This occurs through phosphorylation of the MAPK phosphatase MKP1 and activation of the c-Fos transcription factor by the hyphal form. Given that fungal cell wall polysaccharides are critical in host recognition and immune activation in myeloid cells, we sought to determine whether β-glucan and
N
- or
O
-glycosylation was important in activating the MAPK/MKP1/c-Fos hypha-mediated response mechanism and proinflammatory cytokines in oral epithelial cells. Using a series of β-glucan and
N
- and
O
-mannan mutants, we found that
N
-mannosylation (via Δ
och1
and Δ
pmr1
mutants) and
O
-mannosylation (via Δ
pmt1
and Δ
mnt1
Δ
mnt2
mutants), but not phosphomannan (via a Δ
mnn4
mutant) or β-1,2 mannosylation (via Δ
bmt1
to Δ
bmt6
mutants), were required for MKP1/c-Fos activation, proinflammatory cytokine production, and cell damage induction. However, the
N
- and
O
-mannan mutants showed reduced adhesion or lack of initial hypha formation at 2 h, resulting in little MKP1/c-Fos activation, or restricted hypha formation/pseudohyphal formation at 24 h, resulting in minimal proinflammatory cytokine production and cell damage. Further, the α-1,6-mannose backbone of the
N
-linked outer chain (corresponding to a Δ
mnn9
mutant) may be required for epithelial adhesion, while the α-1,2-mannose component of phospholipomannan (corresponding to a Δ
mit1
mutant) may contribute to epithelial cell damage. β-Glucan appeared to play no role in adhesion, epithelial activation, or cell damage. In summary,
N
- and
O
-mannosylation defects affect the ability of
C. albicans
to induce proinflammatory cytokines and damage in oral epithelial cells, but this may be due to indirect effects on fungal pathogenicity rather than mannose residues being direct activators of the MAPK/MKP1/c-Fos hypha-mediated immune response.
A Metronidazole-Resistant Isolate of Blastocystis spp. Is Susceptible to Nitric Oxide and Downregulates Intestinal Epithelial Inducible Nitric Oxide Synthase by a Novel Parasite Survival Mechanism
Authors: Mirza Haris , Wu Zhaona , Kidwai Fahad , Tan Kevin S. W.
Published: September 2011

Blastocystis
, one of the most common parasites colonizing the human intestine, is an extracellular, noninvasive, luminal protozoan with controversial pathogenesis.
Blastocystis
infections can be asymptomatic or cause intestinal symptoms of vomiting, diarrhea, and abdominal pain. Although chronic infections are frequently reported,
Blastocystis
infections have also been reported to be self-limiting in immunocompetent patients. Characterizing the host innate response to
Blastocystis
would lead to a better understanding of the parasite's pathogenesis. Intestinal epithelial cells produce nitric oxide (NO), primarily on the apical side, in order to target luminal pathogens. In this study, we show that NO production by intestinal cells may be a host defense mechanism against
Blastocystis
. Two clinically relevant isolates of
Blastocystis
, ST-7 (B) and ST-4 (WR-1), were found to be susceptible to a range of NO donors. ST-7 (B), a metronidazole-resistant isolate, was found to be more sensitive to nitrosative stress. Using the Caco-2 model of human intestinal epithelium,
Blastocystis
ST-7 (B) but not ST-4 (WR-1) exhibited dose-dependent inhibition of Caco-2 NO production, and this was associated with downregulation of inducible nitric oxide synthase (iNOS). Despite its higher susceptibility to NO,
Blastocystis
ST-7 (B) may have evolved unique strategies to evade this potential host defense by depressing host NO production. This is the first study to highlight a strain-to-strain variation in the ability of
Blastocystis
to evade the host antiparasitic NO response.
WALL SHEAR STRESS IN A SUBJECT SPECIFIC HUMAN AORTA — INFLUENCE OF FLUID-STRUCTURE INTERACTION
Authors: LANTZ JONAS , RENNER JOHAN , KARLSSON MATTS
Published: September 2011

Vascular wall shear stress (WSS) has been correlated to the development of atherosclerosis in arteries. As WSS depends on the blood flow dynamics, it is sensitive to pulsatile effects and local changes in geometry. The aim of this study is therefore to investigate if the effect of wall motion changes the WSS or if a rigid wall assumption is sufficient. Magnetic resonance imaging (MRI) was used to acquire subject specific geometry and flow rates in a human aorta, which were used as inputs in numerical models. Both rigid wall models and fluid-structure interaction (FSI) models were considered, and used to calculate the WSS on the aortic wall. A physiological range of different wall stiffnesses in the FSI simulations was used in order to investigate its effect on the flow dynamics. MRI measurements of velocity in the descending aorta were used as validation of the numerical models, and good agreement was achieved. It was found that the influence of wall motion was low on time-averaged WSS and oscillating shear index, but when regarding instantaneous WSS values the effect from the wall motion was clearly visible. Therefore, if instantaneous WSS is to be investigated, a FSI simulation should be considered.
FREE VIBRATION OF FUNCTIONALLY GRADED ARBITRARY STRAIGHT-SIDED QUADRILATERAL PLATES RESTING ON ELASTIC FOUNDATIONS
Authors: BENI A. ALIBEYGI
Published: September 2011

The free vibration of functionally graded (FG) arbitrary straight-sided quadrilateral plates rested on two-parameter elastic foundation and in thermal environment is presented. The formulation is based on the first-order shear deformation theory (FSDT). The material properties are assumed to be temperature-dependent and graded in the thickness direction. The solution procedure is composed of transforming the governing equations from physical domain to computational domain and then the discretization of the spatial derivatives by employing the differential quadrature method (DQM) as an efficient and accurate numerical tool. After studying the convergence of the method, its accuracy is demonstrated by comparing the obtained solutions with the existing results in literature for isotropic rectangular and FG rectangular and skew plates. Then, the effects of thickness-to-length ratio, elastic foundation parameters, volume fraction index, geometrical shape and the boundary conditions on the frequency parameters of the FG plates are studied.
Making standard ML a practical database programming language
Authors: Ohori Atsushi , Ueno Katsuhiro
Published: September 2011

Integrating a database query language into a programming language is becoming increasingly important in recently emerging high-level cloud computing and other applications, where efficient and sophisticated data manipulation is required during computation. This paper reports on seamless integration of SQL into SML# - an extension of Standard ML. In the integrated language, the type system always infers a principal type for any type consistent SQL expression. This makes SQL queries first-class citizens, which can be freely combined with any other language constructs definable in Standard ML. For a program involving SQL queries, the compiler separates SQL queries and delegates their evaluation to a database server, e.g. PostgreSQL or MySQL in the currently implemented version.

The type system of our language is largely based on Machiavelli, which demonstrates that ML with record polymorphism can represent type structure of SQL. In order to develop a practical language, however, a number of technical challenges have to be overcome, including static enforcement of server connection consistency, proper treatment of overloaded SQL primitives, query compilation, and runtime connection management. This paper describes the necessary extensions to the type system and compilation, and reports on the details of its implementation.
Designing level 3 behavioral RESTful web service interfaces
Authors: Rauf Irum , Porres Ivan
Published: September 2011

A web service interface contains information about the names of the operations that can be invoked on the service and the input and output parameters of these operations. This information is not enough to facilitate service developer and consumer in understanding the behavior of the service. In the context of RESTful web services, the requirements of RESTful interface should also be met that are not fulfilled by just advertising the allowed operations on the resources. In addition, RESTful services take hypermedia as an engine of application states. Such services are defined to be at level 3 of Richardson Maturity Model(RMM). In this paper, we present an approach to model the structural and behavioral interface of a RESTful web service using UML class and UML protocol diagrams. These models lead to RESTful interfaces that conform to level 3 of RMM and describe the behavior of operations in terms of preconditions and post-conditions. These models facilitate the authentication mechanism and provide clear mapping to HTTP requests and responses. The generated contracts of methods can be published in an extended version of the WADL language and also used for documentation, stub generation, testing and monitoring purposes.
Performance evaluation of scalable video streaming in multihomed mobile networks
Authors: Nightingale James , Wang Qi , Grecos Christos
Published: September 2011

In this paper, we empirically investigate the performance of path selection and packet scheduling algorithms for the delivery of H.264/SVC scalable video streams to users in multihomed mobile networks. These algorithms use the aggregated bandwidth of multiple concurrent paths to deliver media streams in environments where no single, sufficiently high bandwidth path is available. The problems associated with delivering video streams in this challenging environment are examined and the performance of our multihomed mobile networks specific scheme is compared to that of an ideal single high bandwidth path. We further extend previously proposed algorithms by the inclusion of an H.264/SVC-specific packet priority weighting scheme. We highlight the improvements offered by our optimized algorithm over representative algorithms and identify the remaining challenges that must be overcome if such algorithms are to offer performance close to that of the ideal single high bandwidth pat.
Fixed-point approximations of bandwidth sharing networks with rate constraints
Authors: Frolkova Maria , Reed Josh , Zwart Bert
Published: September 2011

Bandwidth sharing networks are important flow level models of communication networks. We focus on the fact that it takes a significant number of users to saturate a link, necessitating the inclusion of individual rate constraints. In particular we extend work of Reed & Zwart on fluid models of bandwidth sharing with rate constraints under Markovian assumptions: we consider a bandwidth sharing network with rate constraints, where job sizes and deadlines have a general joint distribution. We introduce a fluid model and investigate several of its properties. In particular we show that its invariant point approximates the invariant distribution of the bandwidth sharing network if capacities are large.
Poster
Authors: Lübben Ralf , Fidler Markus
Published: September 2011

In this note we present a statistical, non-equilibrium envelope model that, based on Legendre transforms, characterizes source coders and transmission channels by their capacity-delay-error-tradeoff. The model is proven to have the desirable property of additivity, that allows analyzing coders and channels separately. We present an example for Huffman coding. More can be found in the report [2].
Targeting HDACs: A Promising Therapy for Alzheimer's Disease
Authors: Xu Ke , Dai Xue-Ling , Huang Han-Chang , Jiang Zhao-Feng
Published: September 2011

Epigenetic modifications like DNA methylation and histone acetylation play an important role in a wide range of brain disorders. Histone deacetylases (HDACs) regulate the homeostasis of histone acetylation. Histone deacetylase inhibitors, which initially were used as anticancer drugs, are recently suggested to act as neuroprotectors by enhancing synaptic plasticity and learning and memory in a wide range of neurodegenerative and psychiatric disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD). To reveal the physiological roles of HDACs may provide us with a new perspective to understand the mechanism of AD and to develop selective HDAC inhibitors. This paper focuses on the recent research progresses of HDAC proteins and their inhibitors on the roles of the treatment for AD.
The Contribution of Electron Paramagnetic Resonance to Melanoma Research
Authors: Godechal Quentin , Gallez Bernard
Published: September 2011

The incidence of malignant melanoma, the most dangerous form of skin cancer, is rising each year. However, some aspects of the tumor initiation and development are still unclear, and the current method of diagnosis, based on the visual aspect of the tumor, shows limitations. For these reasons, developments of new techniques are ongoing to improve basic knowledge on the disease and diagnosis of tumors in individual patients. This paper shows how electron paramagnetic resonance (EPR), a method able to detect free radicals trapped in melanin pigments, has recently brought its unique value to this specific field. The general principles of the method and the convenience of melanin as an endogenous substrate for EPR measurements are explained. Then, the way by which EPR has recently helped to assess the contribution of ultraviolet rays (UVA and UVB) to the initiation of melanoma is described. Finally, we describe the improvements of EPR spectrometry and imaging in the detection and mapping of melanin pigments insideex vivoandin vivomelanomas. We discuss how these advances might improve the diagnosis of this skin cancer and point out the present capabilities and limitations of the method.
Onℛ4Terms and MHV Amplitudes inN=5,6Supergravity Vacua of Type II Superstrings
Authors: Bianchi Massimo
Published: September 2011

We compute one-loop threshold corrections toℛ4terms inN=5,6supergravity vacua of Type II superstrings. We then discuss nonperturbative corrections generated by asymmetric D-brane instantons. Finally we derive generating functions for MHV amplitudes at tree level inN=5,6supergravities.