bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear and Time-Varying Dynamics of High-Dimensional Models of a Translating Beam With a Stationary Load Subsystem
Authors: Xu G. Y. , Zhu W. D.
Published: October 2010

Nonlinear vibration and dynamic stability analyses of distributed structural systems have often been conducted for their low-dimensional spatially discretized models, and the results obtained from the low-dimensional models may not accurately represent the behaviors of the distributed systems. In this work the incremental harmonic balance method is used to handle a variety of problems pertaining to determining periodic solutions of high-dimensional models of distributed structural systems. The methodology is demonstrated on a translating tensioned beam with a stationary load subsystem and some related systems. With sufficient numbers of included trial functions and harmonic terms, convergent and accurate results are obtained in all the cases. The effect of nonlinearities due to the vibration-dependent friction force between the translating beam and the stationary load subsystem, which results from nonproportionality of the load parameters, decreases as the number of included trial functions increases. A low-dimensional spatially discretized model of the nonlinear distributed system can yield quantitatively and qualitatively inaccurate predictions. The methodology can be applied to other nonlinear and/or time-varying distributed structural systems.
Twinkling Phenomena in Snap-Through Oscillators
Authors: Feeny Brian F. , Diaz Alejandro R.
Published: October 2010

Oscillatory behavior in a chain of masses connected by springs with continuous but nonmonotonic spring forces can be induced under quasistatic loading. An insight into the birth of this behavior is obtained from a single mass system. A bifurcation study shows the potential for equilibrium jumps between multiple equilibria. As such, the transients occurring under quasistatic loading do not converge to the static loading case. Transients during dynamic loading show sensitivity to the loading parameters.
Boundary Control of Large Amplitude Vibration of Anisotropic Composite Laminated Plates
Authors: Rastgoftar Hossein , Eghtesad Mohammad , Khayatian Alireza
Published: October 2010

This paper presents a solution to the stabilization problem of large amplitude vibration of the anisotropic composite laminated plates when the Kirchhoff theorem is used to model geometric equations of strain. Because of the large displacement in the normal direction to the plate, the plate displacements in in-plane directions are not dispensable, and strains and governing equations for transverse vibration and in-plane motions are nonlinear; therefore, the nonlinear boundary control method is proposed to be utilized to stabilize the plate vibration. The boundary control forces consist of feedback of the velocities and slope at the boundary of the plate. By applying the proposed method, it is possible to asymptotically stabilize large amplitude vibration of anisotropic composite plates with simply supported boundary conditions without resorting to truncation of the model and without the use of in-domain measuring and actuating devices.
Vibration Response of Elastic Disks in Surrounding Fluid: Viscous Versus Acoustic Effects
Authors: Jana Anirban , Raman Arvind
Published: October 2010

The vibrations of thin, elastic, circular disks such as musical cymbals, hard disk drives, and microscale resonators are significantly influenced by the presence of a surrounding fluid. The energy of disk vibrations is known to dissipate into viscous losses and to radiate away as sound. However, the relative importance of these mechanisms is not well understood. In this paper, we present three-dimensional computations of the fluidic impedance of thin, elastic disks vibrating with small amplitudes under ambient conditions. These computations encompass both macroscale and microscale disks, a wide range of operating frequencies, and different fluidic environments. Viscous fluidic impedances are computed using a finite element model, whereas acoustic fluidic impedances are computed using a boundary element method. For a disk with a given clamping ratio vibrating in a specific mode, the nondimensional viscous impedance depends on the unsteady Reynolds number, while the nondimensional acoustic impedance depends on the ratio of structural to acoustic wavelengths. It is shown that viscous losses dominate the fluid damping of disks in data storage and circular saw applications and of conventional disk microresonators. However, for ultrahigh frequency resonators, acoustic radiation must be taken into account to correctly estimate the overall fluid damping. The computed fluidic impedances are expected to be an important aid in the design of a wide range of disk resonators up to the megahertz regime.
Modeling perforates in mufflers using two-ports
Authors: Elnady T. , Åbom M. , Allam S.
Published: October 2010

One of the main sources of noise of a vehicle is the engine where its noise is usually damped by means of acoustic mufflers. A very common problem in the modeling of automotive mufflers is that of two flow ducts coupled through a perforate. A new segmentation approach is developed here based on two-port analysis techniques, in order to model perforated pipes using general two-port codes, which are widely available. Examples are given for simple muffler configurations and the convergence of the technique is investigated based on the number of segments used. The results are compared with closed form solutions form the literature. Finally, an analysis of a complicated multichamber perforated muffler system is presented. The two-port simulation results show good agreement with both the measurements, and the simulations using the classical four-port elements.
Investigation of Heat Transfer and Gasification of Two Different Fuel Injectors in an Entrained Flow Coal Gasifier
Authors: Wang Ting , Silaen Armin , Hsu Heng-Wen , Shen Cheng-Hsien
Published: October 2010

One of the problems frequently encountered in a coal gasifier operation is fuel injector failure. Operating in extreme high pressure and high temperature, the typical fuel injector life span is 6–12 months. Numerical simulations are performed to study the flow and temperature fields in the vicinity of the injector tip and the metal temperature of two different fuel injector designs—one with a conical-nozzle tip and the other with a blunt tip—in a dry-fed, entrained-flow coal gasifier. The complete 3D Navier–Stokes equations are solved. The instantaneous gasification model is employed to simulate three global heterogeneous reactions and three homogeneous reactions, including volatile combustion. The results show that the two different injectors give very different temperature and species distributions inside the gasifier. In the gasifier with the conical injector tip, the highest temperature inside the gasifier occurs at the center of the gasifier, whereas in the gasifier with the blunt-tip injector, the highest temperature occurs near the wall. There is a potential of flash-back combustion in the nozzle at the tip of the conical injector due to its premixing feature of fuel and oxidant in the nozzle. The highest temperatures on both injectors are the same, which is around 1600 K. However, the highest temperature on the conical-tip injector is concentrated at one location with an extended region of 30 mm between 1600 K and 1100 K, whereas on the blunt-tip injector, hot spots are scattered and the hot region (1600–1100 K) only extends about 3 mm. Experimental results support the simulated results and has demonstrated a short life of the conical-tip fuel injector and much extended life for the blunt-tip fuel injector.
Predicting Changes in Vibration Behavior With Respect to Multiple Variables Using Empirical Sensitivity Functions
Authors: Yang Chulho , Adams Douglas E.
Published: October 2010

Engineers must routinely predict how structural systems will vibrate after design modifications are made to the mass, damping, or stiffness properties of the components. To reduce the cost of product development, sensitivity prediction methods are desired that can be applied using only empirical data from an initial prototype. Embedded sensitivity functions derived solely from empirical data have previously been applied (a) to identify optimal design modifications for reducing linear vibration resonance problems and (b) to predict the change in frequency response. In this previous work, predictive methods were developed that assumed that only one design parameter in the system was modified. In many applications, it is necessary to extend this approach to all major parameters for a more accurate prediction of the structural dynamic response. This paper utilizes a multivariable Taylor series to take into account multiple parameter changes that affect a broadband frequency range. The method is applied to a single degree of freedom analytical model to determine the accuracy of the predictions. Finite element analyses are then conducted on a three-story structure and an automotive vehicle component with modifications to the stiffness and mass distributions to demonstrate the feasibility of these predictions in applications to more complicated structural systems.
Model Validation for an Active Magnetic Bearing Based Compressor Surge Control Test Rig
Authors: Yoon Se Young , Lin Zongli , Lim Kin Tien , Goyne Christopher , Allaire Paul E.
Published: October 2010

In this paper, we present experimental test data for the validation of a recently introduced mathematical model for centrifugal compression systems with variable impeller axial clearances. Employing the active magnetic bearings (AMBs) of a compressor built for the experimental study of surge, the axial clearance between the impeller and the static shroud is servo controlled, and the measured variations in the compressor output flow are compared with the mathematical model. The steady state and the dynamic responses of the compression system induced by varying the impeller tip clearance are measured and compared with the theoretical predictions, and the states of the compression system in surge condition are collected and analyzed. Parameters in the compression system model, such as the Greitzer parameter B and Helmholtz frequency ωH are experimentally identified. Also, the servo dynamics of the magnetic bearing that controls the axial impeller position is determined experimentally. To further validate the mathematical model and the feasibility of using the impeller tip clearance for controlling surge, we present a design example for an active surge controller based on the derived model, and simulate the response of the compression system. This design exercise also helps us understand the possible challenges that one could face in the design and implementation of a successful surge controller.
Thermal Protection System for Underwater Use in Cold and Hot Water
Authors: Mollendorf Joseph C. , Pendergast David R.
Published: October 2010

Underwater workers, sport and military divers, are exposed to thermal stress since most of the waters of the world are below or above what is thermally neutral. Although divers wear insulation suits for passive thermal protection they are inadequate. Active heating is currently accomplished by resistive heating and open-flow tubes delivering hot water; however, these methods are problematic. The challenge of this project was to design, build and test an active diver thermal protection system (DTPS) to be used with wet suit insulation that is effective, user-friendly, reliable, and that could be used by a free-swimming diver. The DTPS has a minimum number of moving parts, is low maintenance, has no unsafe or toxic working fluid and uses no consumables except a safe, high density, modular electrical power source. A portable and swimmable, self-contained, electrically powered unit (DTPS) has been designed, built, and tested that produces and circulates thermally conditioned water in a closed-loop through a zoned tube suit worn by a diver under a wetsuit to maintain skin and body core temperatures within prescribed safe limits. The system has been validated by using physiological data taken on human subjects over a wide range of ambient water temperatures. Corresponding enthalpy and electrical power measurements were used as the basis of a thermodynamic analysis. The DTPS maintained skin and body core temperatures within safe and functional ranges by providing up to about 200 W of heating in cold water and up to about 330 W of cooling in hot water. The corresponding electrical power consumption was up to about 300 W in cold water and up to about 1500 W in hot water. The results of a complete audit of the power use and heat transfer are presented along with the efficiency of the thermoelectric heating/cooling modules and the duty cycle of the system for a range of water immersion temperatures from 10°C to 39°C. The DTPS proved to be an effective and reliable apparatus for diver thermal protection in water temperatures from 10°C to 39°C, which covers most of the range of the earth’s waters. The data presented here can be used to modify the design of the DTPS to meet specific needs of the diving community.
Enhancement of Convective Heat Transfer in Internal Compressible Flows by Stationary Inserts
Authors: Rahmani Ramin K. , Tanbour Emad Y. , Ayasoufi Anahita , Molavi Hosein
Published: October 2010

Enhancement of the natural and forced convection heat transfer has been the subject of numerous academic and industrial studies. Air blenders, mechanical agitators, and static mixers have been developed to increase the forced convection heat transfer rate in compressible and incompressible flows. Stationary inserts can be efficiently employed as heat transfer enhancement devices in natural and mixed convection systems with compressible flow. These devices have low maintenance and operating costs, low space requirements, and no moving parts. Through numerical studies, this paper demonstrates how an insert improves heat transfer in buoyancy driven flow. The numerical predictions are validated using experimental data. Using different measurement tools, the global performance of the insert and the impact of the geometrical parameters are studied, leading to identification of the most effective design for a given application.
Conjugate Heat Transfer Using Liquid Metals and Alloys for Enclosures With Solid Conducting Blocks
Authors: McGarry M. , Bonilla C. , Metzger I.
Published: October 2010

A validated computational model was created to simulate the heat transfer from a heated surface using liquid metals and alloys during conjugate heat transfer. This model explores the effect of the Rayleigh number, Prandtl number, thermal conductivity ratio, and aspect ratio on the Nusselt number along the hot surface. The data will show how to keep the temperature sensitive components along the hot wall cool by maximizing the amount of heat removed from the hot wall. The data show three distinct regions that occur as a function of the Rayleigh number for a fixed k∗ and d∗. The data also show that the thermal conductivity ratio between the fluid and the solid conducting block has little effect on the Nusselt number at a fixed Rayleigh number. However, when examining the effect of the aspect ratio on the Nusselt number, two distinct regions can be seen. The results demonstrate that in order to keep the temperature sensitive components cool along the hot wall, one would want to have large Rayleigh and Prandtl numbers. The easiest way to achieve large Rayleigh numbers is by increasing the height of the enclosure. Large Prandtl numbers can be achieved by choosing a fluid that is highly conductive. In addition, the choice of material for the center solid conducting block does not impact the amount of heat removed from the hot wall. However, increased cooling can be achieved by decreasing the spacing between the hot and the cold wall.
Two Step Optimization of Transducer Locations in Single Input Single Output Tonal Global Active Noise Control in Enclosures
Authors: Palacios J. Ignacio , Romeu Jordi , Balastegui Andreu
Published: October 2010

Global active control of sound can be achieved inside enclosures under low modal acoustic fields. However, the performance of the system depends largely on the localization of the elements of the control system. For a purely acoustic active control system in which secondary acoustic sources (loudspeakers) and pressure transducers (microphones) as error sensors are used, several optimization strategies have been proposed. These strategies usually rely on partial approximation to the problem, focusing on the study of number and localization of secondary sources without considering error transducers, or selecting the best positions of secondary sources and error transducers of an initial set of candidate locations for these elements. The strategy presented here for tonal global active noise control of steady states comprises two steps; the first is rather common for this sort of problem and its goal is to find the best locations for secondary sources and their strengths by minimizing the potential energy of the enclosure. The second step is the localization of the error transducer, which ensures the results of the first step. It is analytically demonstrated that for a single input single output system, the optimum location of error transducers is at a null pressure point of the optimally attenuated acoustic field. It is also shown that in a real case, the optimum position is that of a minimum of the optimally attenuated acoustic field. Finally, a numerical validation of this principle is carried out in a parallelipedic enclosure.
Computational Fluid Dynamics Analysis of 3D Hot Metal Flow Characteristics in a Blast Furnace Hearth
Authors: Zhou Chenn Q. , Huang D. (Frank) , Zhao Yongfu , Chaubal Pinakin
Published: October 2010

The campaign life of an iron blast furnace depends on hearth wear. Distributions of liquid iron flow and refractory temperatures have a significant influence on hearth wear. A 3D comprehensive computational fluid dynamics model has been developed specifically for simulating the blast furnace hearth. It includes both the hot metal flow and the conjugate heat transfer through the refractories. The model has been extensively validated using measurement data from Mittal Steel old, new IH7 blast furnace and U.S. Steel 13 blast furnace. Good agreements between measured and calculated refractory temperature profiles have been achieved. It has been used to analyze the velocity and temperature distributions and wear patterns of different furnaces and operating conditions. The results can be used to predict the inner profile of hearth and to provide guidance for protecting the hearth.
Evaluation of an Interstitial Cooling Device for Carotid Arterial Cooling Using a Tissue Equivalent Gel Phantom
Authors: Attaluri Anilchandra , Huang Zhongping , Zhu Liang
Published: October 2010

In this study, we build and test a prototype of an interstitial cooling device in a tissue-equivalent gel phantom mimicking the human neck. The effectiveness of the device is measured by the capability of delivering a coolant temperature of lower than 5°C at the entrance of the device and the measured temperature decay along a glass tube filled with water circulating at a speed similar to that in the carotid artery. The experimental study has identified a cooling prototype design, which is capable of inducing sufficient temperature reduction along the common carotid artery. It also tests how easy to handle the device to ensure a close physical contact between the device and the glass tube. A 5°C coolant temperature can be delivered at the device entrance when using above 0°C coolant in the reservoir. The surface temperature of the device is found almost uniform. Despite its limitations, the experimental results agree generally with previous theoretical predictions. The 8 cm long and 3 cm wide device with a coolant temperature lower than 10°C is capable of inducing a temperature reduction of at least 2.5°C along the glass tube filled with water circulating at 240 ml/min. For higher water flow rates, one needs to increase the length of the device and/or lower the coolant temperature to achieve similar temperature decays along the glass tube.
Asymmetric diffusion as a key mechanism in Ni/Al energetic multilayer processing: A first principles study
Authors: Petrantoni M. , Hemeryck A. , Ducéré J. M. , Estève A. , Rossi C. , Rouhani M. Djafari , Estève D. , Landa G.
Published: October 2010

Adsorption and penetration of Al and Ni atoms into Ni(111) and Al(111), respectively, are investigated through first principles calculations, shedding light into the driving forces impacting Al/Ni interfaces produced during multilayer deposition. The authors show that Ni deposition follows an exothermic path toward penetration associated with small activation barriers while Al on Ni(111) path is endothermic accompanied with high activations. Moreover, Ni and Al penetrations proceed through interstitial and substitutional sites, respectively. These differentiated behaviors at early deposition stages illustrate that dual processing conditions are required to achieve the growth of specific Ni/Al interfaces during multilayer deposition processes and that a local melting process at the interface is mandatory to arrive at the formation of a proper barrier layer.
Influence of strain on the hexagonal motifs of the Ir(100) surface reconstructions: A first-principles study
Authors: Su W. S. , Chuang F. C. , Lin K. M. , Leung T. C.
Published: October 2010

The authors performed first-principles calculations to investigate the effect of the strain on the hexagonal motifs formed on the Ir(100) surface overlayer with (5×1), (8×1), (12×1), and (14×1) periodicities. Their calculations showed that the unstrained (5×1) phase is the most stable phase, which is consistent with previous theoretical calculations and experimental findings. Further analysis on the surface energy versus strain suggests the occurrence of the strain induced phase transition among various hexagonal reconstructions. Such a phenomenon can be further qualitatively elucidated by analyzing the computed average standard deviation of angles between the three adjacent atoms of the hexagonal top layer.
Influence of the tip work function on scanning tunneling microscopy and spectroscopy on zinc doped GaAs
Authors: Wijnheijmer A. P. , Garleff J. K. , v. d. Heijden M. A. , Koenraad P. M.
Published: October 2010

The authors investigated the influence of the tip work function on the signatures of zinc in gallium arsenide with scanning tunneling microscopy and spectroscopy. By deliberately inducing tip modifications, the authors can change the tip work function between 3.9 and 5.5 eV, which corresponds to the expected range for tungsten of 3.5–6 eV. The related change in flatband voltage has a drastic effect on both the dI/dV spectra and on the voltage where the typical triangular contrast appears in the topography images. The authors propose a model to explain the differences in the dI/dV spectra for the different tip work functions. By linking the topography images to the spectroscopy data, the authors confirm the generally believed idea that the triangles appear when tunneling into the conduction band is mainly suppressed.
Field-emission of TiSi2 thin film deposited by an in situ chloride-generated route
Authors: Hu Yemin , Li Ying , Zhu Mingyuan , Hu Zheng , Yu Leshu
Published: October 2010

Titanium disilicide (TiSi2) is a high-melting compound with excellent conductivity, which appears to have potential applications in field-emission. In the present article, TiSi2 thin film was successfully synthesized on a silicon wafer through an in situ chloride-generated strategy by atmospheric-pressure chemical-vapor deposition. The required titanium chloride-precursor vapor was in situ produced at an elevated temperature by preloading NiCl2⋅6H2O onto Ti powder with anhydrous ethanol. This synthetic strategy avoided inconvenience with the direct usage of titanium halide or titanium powder as delivering gaseous precursors. The field-emission behavior of the sample shows a turn-on field of 7.2 V/μm and agrees well with the conventional Fowler–Nordheim theory. No obvious degradation was observed in a life-stability experiment period for over 100 min. The convenient and low-cost preparation of the TiSi2 thin film and its fine field-emission performance suggest that it can serve as a good candidate for a field emitter.
Sexually Dimorphic Actions of Glucocorticoids Provide a Link to Inflammatory Diseases with Gender Differences in Prevalence
Authors: Duma Danielle , Collins Jennifer B. , Chou Jeff W. , Cidlowski John A.
Published: October 2010

Glucocorticoids are more effective at counteracting inflammation in males than in females.
Abl to Regulate PCP
Authors: VanHook Annalisa M.
Published: October 2010

Abl tyrosine kinases phosphorylate Dsh to influence planar cell polarity without affecting canonical Wnt signaling.
Shaping Up with Auxin
Authors: Gough Nancy R.
Published: October 2010

AUXIN BINDING PROTEIN 1 mediates rapid auxin responses in roots and leaves.
Location, Location, Location
Authors: Riddihough Guy
Published: October 2010

A critical regulator of cell division is recruited to chromosomes through the specific phosphorylation of a chromatin protein.
Remodeling Gone Awry
Authors: Kiberstis Paula A.
Published: October 2010

Genetic analysis of a rare but aggressive form of ovarian cancer implicates a chromatin remodeling defect in disease development.
Focus Issue: Endocrine Signaling from Clinic to Cell
Authors: Gough Nancy R.
Published: October 2010

Understanding the molecular details of the response to endocrine hormones should improve treatment options and approaches.
Stress and Sex Versus Immunity and Inflammation
Authors: Chrousos George P.
Published: October 2010

Males and females show different responses to stress and to the anti-inflammatory actions of glucocorticoids.
Hormone Resistance at the Clinical LevelA presentation from the third NICHe Conference, “New Inroads to Child Health—Child Health and Signal Transduction,” Varberg, Sweden, 21 to 23 May 2010.
Authors: Hochberg Ze'ev
Published: October 2010

Molecular defects at various steps in hormone production, signaling, or responsiveness can cause disease.
G Protein–Coupled Receptors in Child Development, Growth, and Maturation
Authors: Latronico Ana Claudia , Hochberg Ze’ev
Published: October 2010

Mutations in GPCRs are associated with several disorders that affect the development and maturation of children and adolescents.
Caspofungin Affects Growth of
Paracoccidioides brasiliensis
in Both Morphological Phases
Authors: Rodríguez-Brito Sabrina , Niño-Vega Gustavo , San-Blas Gioconda
Published: October 2010

Five
Paracoccidioides brasiliensis
isolates were grown in the presence of caspofungin (0 to 1 μg/ml). Inhibition of the yeast phase ranged from 20 to 65%, while in the mycelial form it ranged from 75% to 82%. Such variability was loosely related to the amount of cell wall β-1,3-glucan. No association with point mutations in the β-1,3-glucan synthase was detected. Caspofungin induced physical changes and cytoplasmic deterioration in both fungal phases.
Inhibition of Bacterial Multidrug Resistance by Celecoxib, a Cyclooxygenase-2 Inhibitor
Authors: Kalle Arunasree M. , Rizvi Arshad
Published: October 2010

Multidrug resistance (MDR) is a major problem in the treatment of infectious diseases and cancer. Accumulating evidence suggests that the cyclooxygenase-2 (COX-2)-specific inhibitor celecoxib would not only inhibit COX-2 but also help in the reversal of drug resistance in cancers by inhibiting the MDR1 efflux pump. Here, we demonstrate that celecoxib increases the sensitivity of bacteria to the antibiotics ampicillin, kanamycin, chloramphenicol, and ciprofloxacin by accumulating the drugs inside the cell, thus reversing MDR in bacteria.
An Oracle: Antituberculosis Pharmacokinetics-Pharmacodynamics, Clinical Correlation, and Clinical Trial Simulations To Predict the Future
Authors: Pasipanodya Jotam , Gumbo Tawanda
Published: October 2010

Antimicrobial pharmacokinetic-pharmacodynamic (PK/PD) science and clinical trial simulations have not been adequately applied to the design of doses and dose schedules of antituberculosis regimens because many researchers are skeptical about their clinical applicability. We compared findings of preclinical PK/PD studies of current first-line antituberculosis drugs to findings from several clinical publications that included microbiologic outcome and pharmacokinetic data or had a dose-scheduling design. Without exception, the antimicrobial PK/PD parameters linked to optimal effect were similar in preclinical models and in tuberculosis patients. Thus, exposure-effect relationships derived in the preclinical models can be used in the design of optimal antituberculosis doses, by incorporating population pharmacokinetics of the drugs and MIC distributions in Monte Carlo simulations. When this has been performed, doses and dose schedules of rifampin, isoniazid, pyrazinamide, and moxifloxacin with the potential to shorten antituberculosis therapy have been identified. In addition, different susceptibility breakpoints than those in current use have been identified. These steps outline a more rational approach than that of current methods for designing regimens and predicting outcome so that both new and older antituberculosis agents can shorten therapy duration.
High Levels and Safety of Oseltamivir Carboxylate Plasma Concentrations after Nasogastric Administration in Critically Ill Children in a Pediatric Intensive Care Unit
Authors: Giraud Carole , Manceau Sandra , Oualha Mehdi , Chappuy Hélène , Mogenet Agnès , Duchêne Patrick , Ducrocq Sarah , Hubert Philippe , Treluyer Jean M.
Published: October 2010

During the 2009 H1N1 influenza pandemics, the concentrations of oseltamivir (O) and its active metabolite (oseltamivir carboxylate [OC]) were determined in 11 children (1 month to 16 years of age) admitted to intensive care units for presumed severe H1N1 infection. They received oseltamivir phosphate (OP) nasogastrically at doses between 1.5 and 6.8 mg/kg of body weight. High OC concentrations were found, with a mean level of 678 ± 535 μg/liter. The mean OP concentration was 27 ± 52 μg/liter. No marked side effect was reported.
Novel Dengue Virus-Specific NS2B/NS3 Protease Inhibitor, BP2109, Discovered by a High-Throughput Screening Assay
Authors: Yang Chi-Chen , Hsieh Yi-Chen , Lee Shiow-Ju , Wu Szu-Huei , Liao Ching-Len , Tsao Chang-Huei , Chao Yu-Sheng , Chern Jyh-Haur , Wu Chung-Pu , Yueh Andrew
Published: October 2010

Dengue virus (DENV) causes disease globally, with an estimated 25 to 100 million new infections per year. At present, no effective vaccine is available, and treatment is supportive. In this study, we identified BP2109, a potent and selective small-molecule inhibitor of the DENV NS2B/NS3 protease, by a high-throughput screening assay using a recombinant protease complex consisting of the central hydrophilic portion of NS2B and the N terminus of the protease domain. BP2109 inhibited DENV (serotypes 1 to 4), but not Japanese encephalitis virus (JEV), replication and viral RNA synthesis without detectable cytotoxicity. The compound inhibited recombinant DENV-2 NS2B/NS3 protease with a 50% inhibitory concentration (IC50) of 15.43 ± 2.12 μM and reduced the reporter expression of the DENV-2 replicon with a 50% effective concentration (EC50) of 0.17 ± 0.01 μM. Sequencing analyses of several individual clones derived from BP2109-resistant DENV-2 RNAs revealed that two amino acid substitutions (R55K and E80K) are found in the region of NS2B, a cofactor of the NS2B/NS3 protease complex. The introduction of R55K and E80K double mutations into the dengue virus NS2B/NS3 protease and a dengue virus replicon construct conferred 10.3- and 73.8-fold resistance to BP2109, respectively. The E80K mutation was further determined to be the key mutation conferring dengue virus replicon resistance (61.3-fold) to BP2109, whereas the R55K mutation alone did not affect resistance to BP2109. Both the R55K and E80K mutations are located in the central hydrophilic portion of the NS2B cofactor, where extensive interactions with the NS3pro domain exist. Thus, our data provide evidence that BP2109 likely inhibits DENV by a novel mechanism.
Investigation of the Mechanisms by WhichListeria monocytogenesGrows in Porcine Gallbladder Bile
Authors: Dowd Georgina C. , Joyce Susan A. , Hill Colin , Gahan Cormac G. M.
Published: October 2010

The food-borne pathogenListeria monocytogenesis known to colonize the lumen of the gallbladder in infected mice and to grow rapidly in this environment (J. Hardy et al., Science 303:851-853, 2004). However, relatively little is known about the mechanisms utilized by the pathogen to survive and grow in this location. We utilized gallbladder bile (GB bile) isolated directly from porcine gallbladders as anex vivomodel of gallbladder growth. We demonstrate that GB bile is generally nontoxic for bacteria and can readily support growth of a variety of bacterial species includingL. monocytogenes,Lactococcus lactis,Salmonella entericaserovar Typhimurium, andEscherichia coli. Significantly,L. monocytogenesgrew at the same rate as the nonpathogenic speciesListeria innocua, indicating that the pathogen does not possess specialized mechanisms that enable growth in this environment. However, when we reduced the pH of GB bile to pH 5.5 in order to mimic the release of bile within the small intestine, the toxicity of GB bile increased significantly and specific resistance mechanisms (Sigma B, BSH, and BilE) were essential for survival of the pathogen under these conditions. In order to identify genetic loci that are necessary for growth ofL. monocytogenesin the gallbladder, a mariner transposon bank was created and screened for mutants unable to replicate in GB bile. This led to the identification of mutants in six loci, including genes encoding enzymes involved in purine metabolism, amino acid biosynthesis, and biotin uptake. Although GB bile does not represent a significant impediment to bacterial growth, specific metabolic processes are required byL. monocytogenesin order to grow in this environment.
The Early Secretory Pathway Contributes to the Growth of the
Coxiella
-Replicative Niche
Authors: Campoy Emanuel Martín , Zoppino Felipe Carlos Martín , Colombo María Isabel
Published: October 2010

Coxiella burnetii
is a Gram-negative obligate intracellular bacterium. After internalization, this bacterium replicates in a large parasitophorous vacuole that has features of both phagolysosomes and autophagosomal compartments. We have previously demonstrated that early after internalization
Coxiella
phagosomes interact with both the endocytic and the autophagic pathways. In this report, we present evidence that the
Coxiella
-replicative vacuoles (CRVs) also interact with the secretory pathway. Rab1b is a small GTPase responsible for the anterograde transport between the endoplasmic reticulum and the Golgi apparatus. We present evidence that Rab1b is recruited to the CRV at later infection times (i.e., after 6 h of infection). Interestingly, knockdown of Rab1b altered vacuole growth, indicating that this protein was required for the proper biogenesis of the CRV. In addition, overexpression of the active GTPase-defective mutant (GFP-Rab1b Q67L) affected the development of the
Coxiella
-replicative compartment inhibiting bacterial growth. On the other hand, disruption of the secretory pathway by brefeldin A treatment or by overexpression of Sar1 T39N, a defective dominant-negative mutant of Sar1, affected the typical spaciousness of the CRVs. Taken together, our results show for the first time that the
Coxiella
-replicative niche also intercepts the early secretory pathway.
Characterization of aStaphylococcus aureusSurface Virulence Factor That Promotes Resistance to Oxidative Killing and Infectious Endocarditis
Authors: Malachowa Natalia , Kohler Petra L. , Schlievert Patrick M. , Chuang Olivia N. , Dunny Gary M. , Kobayashi Scott D. , Miedzobrodzki Jacek , Bohach Gregory A. , Seo Keun Seok
Published: October 2010

Staphylococcus aureusis a prominent human pathogen and a leading cause of community- and hospital-acquired bacterial infections worldwide. Herein, we describe the identification and characterization of theS. aureus67.6-kDa hypothetical protein, named for thesurface factor promoting resistance tooxidativekilling (SOK) in this study. Sequence analysis showed that the SOK gene is conserved in all sequencedS. aureusstrains and homologous to the myosin cross-reactive antigen ofStreptococcus pyogenes.Immunoblotting and immunofluorescence analysis showed that SOK was copurified with membrane fractions and was exposed on the surface ofS. aureusNewman and RN4220. Comparative analysis of wild-typeS. aureusand an isogenic deletion strain indicated that SOK contributes to both resistance to killing by human neutrophils and to oxidative stress. In addition, theS. aureus sokdeletion strain showed dramatically reduced aortic valve vegetation and bacterial cell number in a rabbit endocarditis model. These results, plus the suspected role of the streptococcal homologue in certain diseases such as acute rheumatic fever, suggest that SOK plays an important role in cardiovascular and other staphylococcal infections.
Conjunctival Transcriptome in Scarring Trachoma
Authors: Burton Matthew J. , Rajak Saul N. , Bauer Julien , Weiss Helen A. , Tolbert Sonda B. , Shoo Alice , Habtamu Esmail , Manjurano Alphaxard , Emerson Paul M. , Mabey David C. W. , Holland Martin J. , Bailey Robin L.
Published: October 2010

Trachoma is a poorly understood immunofibrogenic disease process, initiated byChlamydia trachomatis. Differences in conjunctival gene expression profiles between Ethiopians with trachomatous trichiasis (with [TTI] or without [TT] inflammation) and controls (C) were investigated to identify relevant host responses. Tarsal conjunctival swab samples were collected for RNA isolation andC. trachomatisPCR. Transcriptome-wide microarray experiments were conducted on 42 samples (TTI,n= 13; TT,n= 15; C,n=14). Specific results were confirmed by using multiplex quantitative reverse transcription-PCR for 16 mRNA targets in an independent collection of case-control samples: 386 case-control pairs (TTI,n= 244; TT,n= 142; C,n= 386). The gene expression profiles of cases were consistent with squamous metaplasia (keratins, SPRR), proinflammatory cytokine production (IL1β,CXCL5, andS100A7), and tissue remodeling (MMP7,MMP9,MMP12, andHAS3). There was no difference in the level ofIFNγ between cases and controls. However, cases had increasedINDO,NOS2A, andIL13RA2and reducedIL13.C. trachomatiswas detected in 1/772. Cases show evidence of ongoing inflammation and tissue remodeling, which were more marked where clinical inflammation was also present. Significantly, these processes appear to be active in the absence of currentC. trachomatisinfection. There was limited evidence of a TH1 response (INDOandNOS2A) and no association between a TH2 response and cases. The epithelium appears to be actively involved in late cicatricial stages of trachoma through the production of proinflammatory factors (IL1β,CXCL5, andS100A7). Longitudinal studies are needed to investigate which etiological factors and pathways are associated with progressive scarring and whether simply controlling chlamydial infection will halt progression in people with established cicatricial disease.
ALGEBRAIC QUANTUM HYPERGROUPS II: CONSTRUCTIONS AND EXAMPLES
Authors: DELVAUX L. , VAN DAELE A.
Published: October 2010

Let G be a group and let A be the algebra of complex functions on G with finite support. The product in G gives rise to a coproduct Δ on A making the pair (A,Δ) a multiplier Hopf algebra. In fact, because there exist integrals, we get an algebraic quantum group as introduced and studied in [A. Van Daele, Adv. Math.140 (1998) 323].

Now let H be a finite subgroup of G and consider the subalgebra A1 of functions in A that are constant on double cosets of H. The coproduct in general will not leave this algebra invariant but we can modify Δ and define Δ1 as [Formula: see text] where f ∈ A1, p,q ∈ G and where n is the number of elements in the subgroup H. Then Δ1 will leave the subalgebra invariant (in the sense that the image is in the multiplier algebra M(A1 ⊗ A1) of the tensor product). However, it will no longer be an algebra map. So, in general we do not have an algebraic quantum group but a so-called algebraic quantum hypergroup as introduced and studied in [L. Delvaux and A. Van Daele, Adv. Math.226 (2011) 1134–1167].

Group-like projections in a *-algebraic quantum group A (as defined and studied in [M. B. Landstad and A. Van Daele, arXiv:math.OA/0702458v1]) give rise, in a natural way, to *-algebraic quantum hypergroups, very much like subgroups do as above for a *-algebraic quantum group associated to a group (again see [M. B. Landstad and A. Van Daele, arXiv:math.OA/0702458v1]). In this paper we push these results further. On the one hand, we no longer assume the *-structure as in [M. B. Landstad and A. Van Daele, arXiv:math.OA/0702458v1] while on the other hand, we allow the group-like projection to belong to the multiplier algebra M(A) of A and not only to A itself. Doing so, we not only get some well-known earlier examples of algebraic quantum hypergroups but also some interesting new ones.
COMPLEX STRUCTURES ON FOUR-MANIFOLDS WITH SYMPLECTIC TWO-TORUS ACTIONS
Authors: DUISTERMAAT J. J. , PELAYO A.
Published: October 2010

We apply the general theory for symplectic torus actions with symplectic or coisotropic orbits to prove that a four-manifold with a symplectic two-torus action admits an invariant complex structure and give an identification of those that do not admit a Kähler structure with Kodaira's class of complex surfaces which admit a nowhere vanishing holomorphic (2,0)-form, but are not a torus nor a K3 surface.
ON THE STABILITY OF SYZYGY BUNDLES
Authors: COANDĂ IUSTIN
Published: October 2010

We are concerned with the problem of the stability of the syzygy bundles associated to base-point-free vector spaces of forms of the same degree d on the projective space of dimension n. We deduce directly, from M. Green's vanishing theorem for Koszul cohomology, that any such bundle is stable if its rank is sufficiently high. With a similar argument, we prove the semistability of a certain syzygy bundle on a general complete intersection of hypersurfaces of degree d in the projective space. This answers a question of H. Flenner [Comment. Math. Helv.59 (1984) 635–650]. We then give an elementary proof of H. Brenner's criterion of stability for monomial syzygy bundles, avoiding the use of Klyachko's results on toric vector bundles. We finally prove the existence of stable syzygy bundles defined by monomials of the same degree d, of any possible rank, for n at least 3. This extends the similar result proved, for n = 2, by L. Costa, P. Macias Marques and R. M. Miro-Roig [J. Pure Appl. Algebra214 (2010) 1241–1262]. The extension to the case n at least 3 has been also, independently, obtained by P. Macias Marques in his thesis [arXiv:0909.4646/math.AG (2009)].
NONCOMMUTATIVE MACKEY THEOREM
Authors: DOSI ANAR
Published: October 2010

In this note we investigate quantizations of the weak topology associated with a pair of dual linear spaces. We prove that the weak topology admits only one quantization called the weak quantum topology, and that weakly matrix bounded sets are precisely the min-bounded sets with respect to any polynormed topology compatible with the given duality. The technique of this paper allows us to obtain an operator space proof of the noncommutative bipolar theorem.
PSEUDO–GAUSSIAN SUPERLATTICE
Authors: PAULESCU MARIUS , TULCAN-PAULESCU EUGENIA , GRAVILA PAUL
Published: October 2010

A new family of superlattice structures modulated by the pseudo-Gaussian potential is proposed. The correlation between the configuration of minibands and the superlattice geometry is revealed using the transfer matrix approach.
THE HPP RULE WITH MEMORY AND THE DENSITY CLASSIFICATION TASK
Authors: ALONSO-SANZ RAMÓN
Published: October 2010

This article considers an extension to the standard framework of cellular automata by implementing memory capability in cells. It is shown that the important block HPP rule behaves as an excellent classifier of the density in the initial configuration when applied to cells endowed with pondered memory of their previous states. If the weighing is made so that the most recent state values are assigning the highest weights, the HPP rule surpasses the performance of the best two-dimensional density classifiers reported in the literature.
FLEXIBLE DISSIPATIVE PARTICLE DYNAMICS
Authors: HUANG Z. G. , YUE T. M. , CHAN K. C. , GUO Z. N.
Published: October 2010

Dissipative Particle Dynamics (DPD) has been recognized as a powerful tool for simulating the dynamics of complex fluids on a mesoscopic scale. However, owing to the rigid thermodynamic behavior of the standard model, it has limitations when applied to real systems. Although refined models have been developed to improve the thermodynamic consistency of DPD, they are not without limitations and deficiencies. In this paper, we extend the power of DPD beyond its traditional limits so that it can cope with systems where temperature and pressure changes occur. This is accomplished using a refined model termed Flexible DPD (FDPD), which allows the equation of state (EOS) to be given in priori. As a basis for the development of FDPD, the generalized expression for the thermodynamic variables is derived by solving the Langevin equation of a particle. It is found that the radial distribution function will be approximately invariant under variable transformation if the action range of potential is changed appropriately according to local density. With this invariant character of RDF, and by choosing the force functions to be variable separable, equations relating thermodynamic variables with the functions for DPD interactions are derived, and the weighting function for achieving thermodynamic is designed correspondingly. A case study on the validation of the FDPD method has been undertaken on the adiabatic compression of N2 gas. The simulation results were compared with the theoretical predictions as well as to the simulation results of the ordinary DPD method. The invariant of radial distribution function is justified by the results of the simulation.
POLARITY-DRIVEN GEOMETRICAL CLUSTER GROWTH MODEL OF BUDDING YEAST
Authors: CABRAL RENIEL B. , LIM MAY T.
Published: October 2010

We present a polarity-driven activator-inhibitor model of budding yeast in a two-dimensional medium wherein impeding metabolites secretion (or growth inhibitors) and growth directionality are determined by the local nutrient level. We found that colony size and morphological features varied with nutrient concentration. A branched-type morphology is associated with high impeding metabolite concentration together with a high fraction of distal budding, while opposite conditions (low impeding metabolite concentration, high fraction of proximal budding) promote Eden-type patterns. Increasing the anisotropy factor (or polarity) produced other spatial patterns akin to the electrical breakdown under varying electric field. Rapid changes in the colony morphology, which we conjecture to be equivalent to a transition from an inactive quiescent state to an active budding state, appeared when nutrients were limited.