bluuebunny/crossref_metadata_2025 huggingface dataset:
Operation of a Compression Ignition Engine on Diesel-Diethyl Ether Blends
Authors: Subramanian K. A. , Ramesh A.
Published: January 2009

A detailed investigation on the effect of using diesel-diethyl ether blends in a direct injection diesel engine has been carried out. Blends with 5, 10 & 15% by weight of diethyl ether were tested. The optimum quantity of diethyl ether was found as 10% based on the thermal efficiency. Tests were also conducted with the optimum quantity at an advanced injection timing. With this timing, the blend decreased the smoke & CO level drastically at all loads and increased the brake thermal efficiency at high loads with out affecting NO emissions. It also increased the peak heat release rate, peak pressure and maximum rate of pressure rise. It was concluded that 10% blend with injection timing slight advanced than base diesel operation is suitable.
Emission and Performance Characteristics of a Single Cylinder Compression Ignition Engine Operating on Esterified Rice Bran Vegetable Oil and Diesel Fuel
Authors: Nagaraj A. M. , Prabhu Kumar G. P.
Published: January 2009

The alkyl monoesters of fatty acids derived from vegetable oils or animal fats, known as bio diesel, are attracting considerable interest as an alternative fuel for diesel engines. Biodiesel-fueled engines produce less carbon monoxide, unburnt hydrocarbons, and particulate emissions than diesel-fueled engines. However, bio diesel has different chemical and physical properties than diesel fuel, including a larger bulk modulus and a higher cetane number. Some of these properties can be affected by oxidation of the fuel during storage. These changes can affect the timing of the combustion process and potentially increase the emissions of oxides of nitrogen. The objective of this study was to evaluate the effect of injection and combustion timing on bio diesel combustion and exhaust emissions. Bio diesel fuel is a clean burning fuel made from natural renewable sources such as rice bran vegetable oil. Bio diesel operates in compression ignition engines similar to diesel fuel. It can be burnt in any standard unmodified diesel engine blended with 20% to 30% bio diesel with diesel. Rice bran oil can be converted into bio diesel fuel as ethyl ester by transestirification. Experimental investigations have been carried out using bio diesel as an alternative fuel in single cylinder, compression ignition engine under varying operating conditions and by varying the injection timings with respect to TDC. In this work various parameters such as brake power, peak pressure rise, and emissions during combustion process under varying operating conditions with diesel, bio diesel, bio diesel blends were measured. The exhaust emissions from the engine were measured using exhaust gas analyzer.
Design of Engine Intake Systems Using Computer Simulations
Authors: Ramadan Bassem H. , Gray Charles L. , Schock Harold J. , Hamady Fakhri J. , Hellman Karl H.
Published: January 2009

A computational study of a direct-injection (DI) engine intake system using KIVA-3V was conducted. The engine considered had two intake ports designed to generate a swirling motion of the intake charge in the cylinder. To investigate the effect of adding shrouds to the intake valves on swirl, two sets of intake valves were considered; the first set consisted of conventional valves, and the second set of valves had back shrouds to restrict airflow from the backside of the valves. The effect of port diameters on air flow and swirl motion was also investigated. In this case, ports with two different diameters were modeled. In addition, the effect of using one or two intake ports on swirl generation was determined by blocking one of the ports. The results show that higher swirl was generated with a single port and a shrouded valve.
Analysis of Oil Film Thickness and Heat Transfer on a Piston Ring of a Diesel Engine: Effect of Lubricant Viscosity
Authors: Harigaya Yasuo , Suzuki Michiyoshi , Toda Fujio , Takiguchi Masaaki
Published: January 2009

The effect of lubricant viscosity on the temperature and thickness in oil film on a piston ring in a diesel engine was analyzed by using unsteady state thermohydrodynamic lubrication analysis, that is Reynolds equation and an unsteady state two-dimensional (2-D) energy equation with heat generated from viscous dissipation. The oil film viscosity was then estimated by using the mean oil film temperature and the shear rate for multi grade oils. The shear rate between the ring and liner becomes higher, so that the viscosity for the multi grade oil is affected by the oil film temperature and shear rate, and the viscosity becomes lower. Under low temperature condition, the viscosity becomes lower due to viscous heating and shear rate and under higher temperature condition, the viscosity affected by the shear rate becomes lower. The oil film thickness between the ring and liner decreases with decrease of the oil viscosity, and it is the thinnest that the oil film thickness is calculated by using the viscosity estimated by both the shear rate and the oil film temperature. Moreover, the heat transfer at ring and liner surfaces was examined.
Optimum Use of Noble Metal Catalysts in Catalytic Converters
Authors: Lacin F. , Zhuang M.
Published: January 2009

The catalytic converter is an important device for the emission control from spark-ignition engines. Several concurrent physical/chemical processes such as convective heat transfer, gas phase chemical reactions, surface reactions, flow oscillations, water vapor condensation and diffusion mechanisms add complexity to modeling of flows inside catalytic converters. Under cold-start conditions, the fact that catalytic converters do not become operational during the initial operation allows a significant fraction of the overall pollutants to be emitted. In the present study, these complex transient phenomena have been examined using a previously validated numerical model.1 The numerical results suggest new material-dependent designs to improve both the transient conversion characteristics and the steady state conversion efficiency of catalytic converters. Moreover, from our model calculations, we have observed that for a given amount of the noble metal catalysts the light-off time and the monolith temperature are greatly affected by the noble-metal distribution along the honeycomb walls of a monolith. The results of the numerical simulations indicate that the light-off time is shortened by approximately 35% for CO, H2 and C3H6 when replacing a traditional homogeneous noble metal distribution by a simple, step-function distribution.2 The emissions of CO, H2 and C3H6 from the exhaust gas are, therefore, reduced without increasing the cost of noble metal catalysts used in converters. In order to avoid further deterioration of catalysts due to the thermal effects, an optimum noble metal distribution needs to be investigated with the understanding that the optimum noble metal distribution proposed has to be practical for the manufacturing. Since the main source of the exhaust emissions is generated during the cold-start period of the converter operation, the reduction of emissions shown in our model calculations is quite substantial.
Effect of Soot Radiation on Flame Temperature, NOx-Emission and Wall Heat Transfer in a Medium Speed Diesel Engine
Authors: Taskinen Pertti
Published: January 2009

The main aim in this study was to investigate the effect of soot radiation on the maximum flame temperature, the total heat flux to wall and the NOx-emission levels in a medium speed diesel engine. Also the effect of turbulence models (STD or RNG k-epsilon) the combustion and emission results were investigated. The RNG k-epsilon model was modified as part of the velocity dilatation term by using an analysis of rapid spherical distortion. In the modified KIVA2-CFD code the Magnussen EDC (Eddy Dissipation Concept) model was used for the fuel vapor combustion, the Tesner & Magnussen model for the soot formation, the combined Magnussen EDC/Nagle & Strickland-Constable for the soot combustion, the extended Zeldovich model for the NO-formation and the chi-squared model for the spray. Radiative heat transfer was dealt with in two ways, in the first the simplified method was used (pure soot emission) and in the second the radiative transport equation was solved with the discrete ordinate method (DOM). The soot absortion coefficient was calculated with the correlation of Kent & Honnery. The computations were done with and without radiant heat loss in order to observe the effect of soot radiation in the results. The predicted cylinder pressures and the heat release rates in both cases were compared with the corresponding measured data. The soot, NOx and heat flux results were compared to the results obtained from literature, due to the non-availability of measured data. The predicted results are reasonable and behaved correctly. The simulation results show that the effect of soot radiation in the combustion process is remarkable and therefore it has to be taken into consideration when modelling diesel engine processes. Also the modified RNG k-epsilon model yields slightly more realistic combustion results than the STD k-epsilon model.
Thermophysical Properties of Working Substance and Heat Transfer in a Hydrogen Combustion Engine
Authors: Shudo T. , Oka H.
Published: January 2009

Hydrogen is a clean alternative to fossil fuels for internal combustion engines and can be easily used in spark-ignition engines. However, the characteristics of the engines fueled with hydrogen are largely different from those with conventional hydrocarbon fuels. A higher burning velocity and a shorter quenching distance for hydrogen as compared with hydrocarbons bring a higher degree of constant volume and a larger heat transfer from the burning gas to the combustion chamber wall of the engines. Because of the large heat loss, the thermal efficiency of an engine fueled with hydrogen is sometimes lower than that with hydrocarbons. Therefore, the analysis and the reduction of the heat loss are crucial for the efficient utilization of hydrogen in internal combustion engines. The empirical correlations to describe the total heat transferred from the burning gas to the combustion chamber walls are often used to calculate the heat loss in internal combustion engines. However, the previous research by one of the authors has shown that the widely used heat transfer correlations cannot be properly applied to the hydrogen combustion even with adjusting the constants in them. For this background, this research analyzes the relationship between characteristics of thermophysical properties of working substance and heat transfer to the wall in a spark-ignition engine fueled with hydrogen.
Virtual Valve Design for Three Dimensional Numerical Simulations of a Large-Bore Natural Gas Engine
Authors: Kim Gi-Heon , Kirkpatrick Allan T. , Mitchell Charles E.
Published: January 2009

One of the promising mixing enhancement technologies for natural gas engines currently used is high pressure fuel injection. Three dimensional computational simulations that can examine the entire injection and mixing process in engines using high pressure injection and determine the impact of injector design on engine performance are consequently of considerable interest. However, the cost of three dimensional engine simulations including a moving piston and the kinetics of combustion and pollutants production quickly becomes considerable in terms of simulation time requirements. The limiting factor is the modeling of the small length scales of the poppet valve flow. Such length scales can be two orders of magnitude smaller than cylinder length scales. The objective of this paper is to describe the development of a compatible virtual valve which can be substituted in three-dimensional numerical models for the complex shrouded poppet valve injection system actually installed in the engine to be simulated. Downstream flow characteristics of the jets from an actual valve and a virtual valve were compared. Various mixing parameters were evaluated in moving piston simulations that include the effect of the jet-piston interaction. Comparison of the results indicated that it is possible to design a simple converging-diverging fuel nozzle that will produce the same jet and subsequently the same large and turbulent scale mixing patterns as a real poppet valve.
Computational Study of Fuel Injection in a Large-Bore Gas Engine
Authors: Chowdhury Snehaunshu , Nalim Razi , Sine Thomas M.
Published: January 2009

Emission controls in stationary gas engines have required significant modifications to the fuel injection and combustion processes. One approach has been the use of high-pressure fuel injection to improve fuel-air mixing. The objective of this study is to simulate numerically the injection of gaseous fuel at high pressure in a large-bore two-stroke engine. Existing combustion chamber geometry is modeled together with proposed valve geometry. The StarCD® fluid dynamics code is used for the simulations, using appropriate turbulence models. High-pressure injection of up to 500 psig methane into cylinder air initially at 25 psig is simulated with the valve opened instantaneously and piston position frozen at the 60 degrees ABDC position. Fuel flow rate across the valve throat varies with the instantaneous pressure but attains a steady state in approximately 22 ms. As expected with the throat shape and pressures, the flow becomes supersonic past the choked valve gap, but returns to a subsonic state upon deflection by a shroud that successfully directs the flow more centrally. This indicates the need for careful shroud design to direct the flow without significant deceleration. Pressures below 300 psig were not effective with the proposed valve geometry. A persistent re-circulation zone is observed immediately below the valve, where it does not help promote mixing.
Native E. coli inner membrane incorporation in solid-supported lipid bilayer membranes
Authors: Dodd Charlotte E. , Johnson Benjamin R. G. , Jeuken Lars J. C. , Bugg Timothy D. H. , Bushby Richard J. , Evans Stephen D.
Published: January 2009

Solid-supported bilayer lipid membranes (SBLMs) containing membrane protein have been generated through a simple lipid dilution technique. SBLM formation from mixtures of native Escherichia coli bacterial inner membrane (IM) vesicles diluted with egg phosphatidylcholine (egg PC) vesicles has been explored with dissipation enhanced quartz crystal microbalance (QCM-D), atomic force microscopy (AFM), attenuated total internal-reflection Fourier-transform infrared spectroscopy (ATR-FTIR), and fluorescence recovery after photobleaching (FRAP). QCM-D studies reveal that SBLM formation from vesicle mixtures ranging between 0% and 100% IM can be divided into two regimes. Samples with ≤40% IM form SBLMs, while samples of greater IM fractions are dominated by vesicle adsorption. FRAP experiments showed that the bilayers formed from mixed vesicles with ≤40% IM were fluid, and comprised a mixture of both egg PC and IM. ATR-FTIR measurements on SBLMs membranes formed with 30% IM confirm that protein is present. SBLM formation was also explored as a function of temperature by QCM-D and FRAP. For samples of 30% IM, QCM-D data show a decreased mass and viscoelasticity at elevated temperatures, and an increased fluidity is observed by FRAP measurements. These results suggest improved biomimetic characteristics can be obtained by forming and maintaining the system at, or close to, 37 °C.
Lipid redistribution in phosphatidylserine-containing vesicles adsorbing on titania
Authors: Khan Tabrisur Rhaman , Grandin H. Michelle , Mashaghi Alireza , Textor Marcus , Reimhult Erik , Reviakine Ilya
Published: January 2009

Lipid vesicles (liposomes) exhibit a wide range of behavior at inorganic (oxide) surfaces. A complete understanding of the vesicle-surface interactions, and of the ensuing transformations surface adsorbed liposomes undergo, has proven elusive. This is at least in part due to the large number of degrees of freedom of the system comprising vesicles with their molecular constituents, substrate surface, and electrolyte solution. The least investigated among these degrees of freedom are those intrinsic to the vesicles themselves, involving rearrangements of lipid molecules. In this study, the adsorption of two-component vesicles (phosphatidylcholine:phosphatidylserine) on titanium dioxide was investigated by dual polarization interferometry. Mixtures of these two lipids containing more than 20% of phosphatidylserine form supported bilayers on titania, with phosphatidylserine predominantly facing the surface of the oxide. The purpose of this investigation is to ascertain whether redistribution of phosphatidylserine occurs already in the adsorbing vesicles. Indeed, this was found to be the case. A possible mechanism of this process is discussed.
From diffraction to imaging: New avenues in studying hierarchical biological tissues with x-ray microbeams (Review)
Authors: Paris Oskar
Published: January 2009

Load bearing biological materials such as bone or arthropod cuticle have optimized mechanical properties which are due to their hierarchical structure ranging from the atomic/molecular level up to macroscopic length scales. Structural investigations of such materials require new experimental techniques with position resolution ideally covering several length scales. Beside light and electron microscopy, synchrotron radiation based x-ray imaging techniques offer excellent possibilities in this respect, ranging from full field imaging with absorption or phase contrast to x-ray microbeam scanning techniques. A particularly useful approach for the study of biological tissues is the combination x-ray microbeam scanning with nanostructural information obtained from x-ray scattering [small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS)]. This combination allows constructing quantitative images of nanostructural parameters with micrometer scanning resolution, and hence, covers two length scales at once. The present article reviews recent scanning microbeam SAXS/WAXS work on bone and some other biological tissues with particular emphasis on the imaging capability of the method. The current status of instrumentation and experimental possibilities is also discussed, and a short outlook about actual and desirable future developments in the field is given.
X-ray spectromicroscopy study of competitive adsorption of protein and peptide onto polystyrene-poly(methyl methacrylate)
Authors: Leung Bonnie O. , Hitchcock Adam P. , Brash John L. , Scholl Andreas , Doran Andrew , Henklein Peter , Overhage Joerg , Hilpert Kai , Hale John D. , Hancock Robert E. W.
Published: January 2009

A synchrotron-based x-ray photoemission electron microscope (X-PEEM) was used to investigate the coadsorption of a mixture of human albumin serum and SUB-6, a synthetic antimicrobial peptide, to a phase-segregated polystyrene/poly(methyl methacrylate) (PMMA) substrate at varying concentrations and pH. The authors show that X-PEEM could detect the peptide adsorbed from solution at concentrations as low as 5.5×10−9M and could differentiate the four components via near-edge x-ray absorption fine structure spectromicroscopy. At neutral pH the SUB-6 peptide adsorbed preferentially to PMMA. At a pH of 11.8 where the charge on the peptide was neutralized, there was a more balanced adsorption of both species on the PMMA domains. The authors interpret these observations as indicative of the formation of an electrostatic complex between positive peptide and negative protein at pH of 7.0. This solution complex had an adsorption behavior that depended on the polarity of the substrate domains, and favored adsorption to the electronegative PMMA regions. At a pH of 11.8 the complex formation was suppressed and a more competitive adsorption process was observed.
Electrochemical switching of the flavoprotein dodecin at gold surfaces modified by flavin-DNA hybrid linkers
Authors: Grininger Martin , Nöll Gilbert , Trawöger Sibylle , Sinner Eva-Kathrin , Oesterhelt Dieter
Published: January 2009

Dodecin from Halobacterium salinarum is a dodecameric, hollow-spherical protein, which unspecifically adopts flavin molecules. Reduction of flavin dodecin holocomplexes induces dissociation into apododecin and free flavin. Unspecific binding and dissociation upon reduction were used as key properties to construct an electrochemically switchable surface, which was able to bind and release dodecin apoprotein depending on the applied potential. A flavin modified electrode surface (electrode-DNA-flavin) was generated by direct adsorption of double stranded DNA (ds-DNA) equipped with flavin and disulfide modifications at opposite ends. While the disulfide functionality enabled anchoring the ds-DNA at the gold surface, the flavin exposed at the surface served as the redox-active dodecin docking site. The structures of protein and flavin-DNA hybrid ligands were optimized and characterized by x-ray structural analysis of the holocomplexes. By surface plasmon resonance (SPR) spectroscopy, the adsorption of flavin modified DNA as well as the binding and the electrochemically induced release of dodecin apoprotein could be shown. When the surface immobilization protocol was changed from direct immobilization of the modified ds-DNA to a protocol, which included the hybridization of flavin and thiol modified DNA at the surface, the resulting monolayer was electrochemically inactive. A possible explanation for the strong influence of the surface immobilization protocol on addressing dodecin by the applied potential is that electron transfer is rather mediated by defects in the monolayer than modified ds-DNA.
Structure from substrate supported lipid bilayers (Review)
Authors: Katsaras John , Kučerka Norbert , Nieh Mu-Ping
Published: January 2009

Highly aligned, substrate supported membranes have made it possible for physical techniques to extract unambiguous structural information previously not accessible from commonly available membrane dispersions, or so-called powder samples. This review will highlight some of the major breakthroughs in model membrane research that have taken place as a result of substrate supported samples.
Biosensors based on surface plasmon-enhanced fluorescence spectroscopy (Review)
Authors: Dostálek Jakub , Knoll Wolfgang
Published: January 2009

The implementation of surface plasmon-enhanced fluorescence spectroscopy (SPFS) to surface plasmon resonance (SPR) biosensors enables increasing their sensitivity by several orders of magnitude. In SPR-based biosensors, surface plasmons probe the binding of target molecules contained in a liquid sample by their affinity partners attached to a metallic sensor surface. SPR biosensors relying on the detection of refractive index changes allow for direct observation of the binding of large and medium size molecules that produces sufficiently large refractive index changes. In SPR biosensors exploiting SPFS, the capture of fluorophore-labeled molecules to the sensor surface is observed by the detection of fluorescence light emitted from the surface. This technique takes advantage of the enhanced intensity of electromagnetic field accompanied with the resonant excitation of surface plasmons. The interaction with surface plasmons can greatly increase the measured fluorescence signal through enhancing the excitation rate of fluorophores and by more efficient collecting of fluorescence light. SPFS-based biosensors were shown to enable the analysis of samples with extremely low analyte concentrations and the detection of small molecules. In this review, we describe the fundamental principles, implementations, and current state of the art applications of SPFS biosensors. This review focuses on SPFS-based biosensors employing the excitation of surface plasmons on continuous metal-dielectric interfaces.
Composite biomolecule/PEDOT materials for neural electrodes
Authors: Asplund Maria , von Holst Hans , Inganäs Olle
Published: January 2009

Electrodes intended for neural communication must be designed to meet both the electrochemical and biological requirements essential for long term functionality. Metallic electrode materials have been found inadequate to meet these requirements and therefore conducting polymers for neural electrodes have emerged as a field of interest. One clear advantage with polymer electrodes is the possibility to tailor the material to have optimal biomechanical and chemical properties for certain applications. To identify and evaluate new materials for neural communication electrodes, three charged biomolecules, fibrinogen, hyaluronic acid (HA), and heparin are used as counterions in the electrochemical polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). The resulting material is evaluated electrochemically and the amount of exposed biomolecule on the surface is quantified. PEDOT:biomolecule surfaces are also studied with static contact angle measurements as well as scanning electron microscopy and compared to surfaces of PEDOT electrochemically deposited with surfactant counterion polystyrene sulphonate (PSS). Electrochemical measurements show that PEDOT:heparin and PEDOT:HA, both have the electrochemical properties required for neural electrodes, and PEDOT:heparin also compares well to PEDOT:PSS. PEDOT:fibrinogen is found less suitable as neural electrode material.
Bioinformatics and breast cancer: what can high-throughput genomic approaches actually tell us?
Authors: Sims A H
Published: January 2009

High-throughput genomic technology has rapidly become a major tool for the study of breast cancer. Gene expression profiling has been applied to many areas of research from basic science to translational studies, with the potential to identify new targets for treatment, mechanisms of resistance and to improve on current tools for the analysis of prognosis. However, the sheer scale of the data generated along with the number of different protocols, platforms and analysis methods can make these studies difficult for clinicians to comprehend. Similarly, computational scientists and statisticians that may be called upon to analyse the data generated are often unaware of the processes involved in sample collection or the relevance and impact of genetics and pathological characteristics. There is a pressing need for better understanding of the challenges and limitations of microarray approaches, both in experimental design and data analysis. Holistic, whole-genome approaches are still relatively new and critics have been quick to highlight non-overlapping results from groups testing similar hypotheses. However, it is often subtle differences in the experimental design and technology that underpin the variation between these studies. Rather than indicating that the data are meaningless, this suggests that many findings are real, but highly context dependent. This review explores both the current state and potential of bioinformatics to bring meaning to high-throughput genomic approaches in the understanding of breast cancer.
Study on the effect of two different projects on commuter rail line capacity
Authors: Öztürk Zübeyde , Öztürk Turgut
Published: January 2009

In this study, the effect of two different projects on the capacity of a commuter rail line is explored. The study reviews line capacities in the case of a mixed operating system or in the case of operation of commuter trains only. Commuter rail lines operated in two regions of Istanbul are taken as an example. These quite inefficient lines will be modernized and joined and integrated. Two projects exist for updating and integrating these lines, one of which is the Marmaray project. Under the ongoing Marmaray project planned for completion in 2010, the Bosporus will be crossed through a tube that will join the commuter rail lines in the neighboring continents. Another planning alternative, in addition to the Marmaray project, is to build a suspended bridge to serve railway traffic and to allocate this line to high-speed trains and other long-distance trains. This will enable operation of commuter trains and high-speed trains on separate lines. Commuter rail line capacities for both modes of operation are calculated separately using line data and the results are reviewed.
PET study of11C-acetoacetate kinetics in rat brain during dietary treatments affecting ketosis
Authors: Bentourkia M'hamed , Tremblay Sébastien , Pifferi Fabien , Rousseau Jacques , Lecomte Roger , Cunnane Stephen
Published: January 2009

Normally, the brain's fuel is glucose, but during fasting it increasingly relies on ketones (β-hydroxybutyrate, acetoacetate, and acetone) produced in liver mitochondria from fatty acid β-oxidation. Although moderately raised blood ketones produced on a very high fat ketogenic diet have important clinical effects on the brain, including reducing seizures, ketone metabolism by the brain is still poorly understood. The aim of the present work was to assess brain uptake of carbon-11-labeled acetoacetate (11C-acetoacetate) by positron emission tomography (PET) imaging in the intact, living rat. To vary plasma ketones, we used three dietary conditions: high carbohydrate control diet (low plasma ketones), fat-rich ketogenic diet (raised plasma ketones), and 48-h fasting (raised plasma ketones).11C-acetoacetate metabolism was measured in the brain, heart, and tissue in the mouth area. Using11C-acetoacetate and small animal PET imaging, we have noninvasively quantified an approximately seven- to eightfold enhanced brain uptake of ketones on a ketogenic diet or during fasting. This opens up an opportunity to study brain ketone metabolism in humans.
Evidence for a Critical Period in the Development of Excitability and Potassium Currents in Mouse Lumbar Superficial Dorsal Horn Neurons
Authors: Walsh M. A. , Graham B. A. , Brichta A. M. , Callister R. J.
Published: January 2009

The output of superficial dorsal horn (SDH; laminae I–II) neurons is critical for processing nociceptive, thermal, and tactile information. Like other neurons, the combined effects of synaptic inputs and intrinsic membrane properties determine their output. It is well established that peripheral synaptic inputs to SDH neurons undergo extensive reorganization during pre- and postnatal development. It is unclear, however, how membrane properties or the subthreshold whole cell currents that shape SDH neuron output change during this period. Here we assess the intrinsic membrane properties and whole cell currents in mouse SDH neurons during late embryonic and early postnatal development (E15–P25). Transverse slices were prepared from lumbar spinal cord and whole cell recordings were obtained at 32°C. During this developmental period resting membrane potential (RMP) became more hyperpolarized (by ∼10 mV, E15–E17 vs. P21–P25) and input resistance decreased (1,074 ± 78 vs. 420 ± 27 MΩ). In addition, action potential (AP) amplitude and AP afterhyperpolarization increased, whereas AP half-width decreased. Before and after birth (E15–P10), AP discharge evoked by intracellular current injection was limited to a single AP at depolarization onset in many neurons (>41%). In older animals (P11–P25) this changed, with AP discharge consisting of brief bursts at current onset (∼46% of neurons). Investigation of major subthreshold whole cell currents showed the rapid A-type potassium current ( IAr) dominated at all ages examined (90% of neurons at E15–E17, decreasing to >50% after P10). IAr expression levels, based on peak current amplitude, increased during development. Steady-state inactivation and activation for IAr were slightly less potent in E15–E17 versus P21–P25 neurons at potentials near RMP (−55 mV). Together, our data indicate that intrinsic properties and IAr expression change dramatically in SDH neurons during development, with the greatest alterations occurring on either side of a critical period, P6–P10.
Circulating Tissue Inhibitor of Matrix Metalloproteinase‐4 (TIMP‐4) in Systemic Sclerosis Patients with Elevated Pulmonary Arterial Pressure
Authors: Elias Gialafos J. , Ioannis Moyssakis , Theodora Psaltopoulou , Dimitrios Papadopoulos P. , Despoina Perea , Kostantinos Vlasis , Charalampos Kostopoulos , Vassilios Votteas , Petros Sfikakis P.
Published: January 2009

Decreased levels of matrix metalloproteinases (MMPs) or excess levels of their tissue inhibitors (TIMPs) may contribute to dysregulation of extracellular matrix turnover in systemic sclerosis (SSc). In a cross‐sectional study of 106 SSc patients, we measured serum levels of TIMP‐4 which is preferentially expressed in cardiovascular structures and searched for correlations with simultaneously performed echocardiography measurements of pulmonary artery systolic pressure (PASP), myocardial performance, and pulmonary function tests. TIMP‐4, but not MMP‐9, levels were significantly raised in patients with SSc than controls. However, in the subgroup of patients with PASP measurements lower to 40 mmHg (n= 69), TIMP‐4 levels were comparable to controls irrespective of the presence of diffuse or limited skin involvement, or lung fibrosis. Individual PASP measurements suggestive of pulmonary hypertension were associated with increased TIMP‐4 serum levels (P= .03), independently of age, extent of skin sclerosis, or lung fibrosis, suggesting a cardiopulmonary vasculature‐specific role of TIMP‐4 activation in SSc.
Computerized Interactive Gaming via Supporting Vector Machines
Authors: Jiang Y. , Jiang J. , Palmer I. J.
Published: January 2009

Computerized interactive gaming requires automatic processing of large volume of random data produced by players on spot, such as shooting, football kicking, and boxing. This paper describes a supporting vector machine‐based artificial intelligence algorithm as one of the possible solutions to the problem of random data processing and the provision of interactive indication for further actions. In comparison with existing techniques, such as rule‐based and neural networks, and so forth, our SVM‐based interactive gaming algorithm has the features of (i) high‐speed processing, providing instant response to the players, (ii) winner selection and control by one parameter, which can be predesigned and adjusted according to the needs of interaction and game design or specific level of difficulties, and (iii) detection of interaction points is adaptive to the input changes, and no labelled training data is required. Experiments on numerical simulation support that the proposed algorithm is robust to random noise, accurate in picking up winning data, and convenient for all interactive gaming designs.
The Characterizations of Extreme Amenability of Locally Compact Semigroups
Authors: Masiha Hashem
Published: January 2009

We demonstrate that the characterizations of topological
extreme amenability. In particular, we prove that for every locally compact
semigroup S with a right identity, the condition μ⊙(F × G) = (μ⊙F) × (μ⊙G), for F, G in M(S) ∗, and 0 < μ ∈ M(S), implies that μ = εa, for some a ∈ S (εa is a Dirac measure). We also obtain the
conditions for which M(S) ∗ is topologically extremely left amenable.
Chronic Brucellosis Patients Retain Low Frequency of CD4+ T-Lymphocytes Expressing CD25 and CD28 afterEscherichia coliLPS Stimulation of PHA-Cultured PBMCs
Authors: Skendros Panagiotis , Sarantopoulos Alexandros , Tselios Konstantinos , Boura Panagiota
Published: January 2009

Chronic brucellosis patients display a defective Th1 response to PHA. We have previously shown that heat-killed B. abortus (HKBA) can downregulate the PHA-induced increase of CD4+/CD25+ and CD14+/CD80+ cells of brucellosis patients. In the present study, we investigate the effect ofE. coliLPS, as a potent stimulant of monocytes and autologous T-lymphocytes, on the PHA-cultured PBMCs of the same groups of patients. Thirteen acute brucellosis (AB) patients, 22 chronic brucellosis (CB) patients, 11 “cured” subjects, and 15 healthy volunteers were studied. The percentage of CD4+/CD25+ and CD4+/CD28+ T-lymphocytes as well as CD14+/CD80+ monocytes were analyzed by flow cytometry after PBMCs culture with PHA plusE. coliLPS. A significant decrease in the percentage of CD4+/CD25+ and CD4+/CD28+ T-lymphocytes was observed in CB compared to AB. In HKBA cultures, compared toE. coliLPS-cultures, there was a significant reduction of CD4+/CD25+ T-lymphocytes in all groups and CD14+/CD80+ in patients groups. We suggest that Brucella can modulate host immune response, leading to T-cell anergy and chronic infection.
Proactive Agents to Assist Multimodal Explorative Learning of Astronomical Phenomena
Authors: Tuominen Eva , Kangassalo Marjatta , Hietala Pentti , Raisamo Roope , Peltola Kari
Published: January 2009

This paper focuses on developing, testing, and examining the Proagents multimodal learning environment to support blind children's explorative learning in the area of astronomy. We utilize haptic, auditive, and visual interaction. Haptic and auditory feedbacks make the system accessible to blind children. The system is used as an exploration tool for children's spontaneous and question-driven explorations. High-level interaction and play are essential with environments for young children. Proactive agents support and guide children to deepen their explorations and discover the central concepts and relations in phenomena. It has been challenging to integrate together in a pedagogically relevant way the explorative learning approach, proactive agents' actions, haptic perception's possibilities, and the selected astronomical phenomena. Our tests have shown that children are very interested in using the system and the operations of the agents.
Dynamical Model to Describe the Interactions between the Chemical Components in Environment of Photopolymerization of MMA by Dye/Amine Systems
Authors: Magini Marcio , Rodrigues Máira R.
Published: January 2009

This work discusses the model that explains the aspects of photopolymerization of methyl methacrylate initiated by dye/amine systems. This model is based on a simulation that uses differential equations. A similar model following the hypothesis presented here was used with success in a preliminary work, by Magini and Rodrigues (2005), to describe the cationic photopolymerization of THF in the presence of sensitizers/sulfonium salt systems. Using the same structure was possible to generate a straight correlation between experimental and theoretical results for this system, free radically initiated, opening an important theoretical understanding about the photopolymerization systems and their chemical relations during the reaction.
Jordan ∗‐Derivations on C∗‐Algebras and JC∗‐Algebras
Authors: Su An Jong , Cui Jianlian , Park Choonkil
Published: January 2009

We investigate Jordan ∗‐derivations on C∗‐algebras and Jordan ∗‐derivations on JC∗‐algebras associated with the following functional inequality ∥f(x) + f(y) + kf(z)∥ ≤ ∥kf((x + y)/k + z)∥ for some integer k greater than 1. We moreover prove the generalized Hyers‐Ulam stability of Jordan ∗‐derivations on C∗‐algebras and of Jordan ∗‐derivations on JC∗‐algebras associated with the following functional equation f((x + y)/k + z) = (f(x) + f(y))/k + f(z) for some integer k greater than 1.
Dynamics of Cohen‐Grossberg Neural Networks with Mixed Delays and Impulses
Authors: Yang Xinsong , Huang Chuangxia , Zhang Defei , Long Yao
Published: January 2009

Impulsive Cohen‐Grossberg neural networks with bounded and unbounded delays (i.e., mixed delays) are investigated. By using the Leray‐Schauder fixed point theorem, differential inequality techniques, and constructing suitable Lyapunov functional, several new sufficient conditions on the existence and global exponential stability of periodic solution for the system are obtained, which improves some of the known results. An example and its numerical simulations are employed to illustrate our feasible results.
Disruption of Nrf2 Enhances Upregulation of Nuclear Factor‐κB Activity, Proinflammatory Cytokines, and Intercellular Adhesion Molecule‐1 in the Brain after Traumatic Brain Injury
Authors: Jin Wei , Wang Handong , Yan Wei , Xu Lizhi , Wang Xiaoliang , Zhao Xiaoning , Yang Xiaohe , Chen Gang , Ji Yan
Published: January 2009

Inflammatory response plays an important role in the pathogenesis of secondary brain injury after traumatic brain injury (TBI). Nuclear factor erythroid 2‐related factor 2 (Nrf2) is a key transcription factor that plays a crucial role in cytoprotection against inflammation. The present study investigated the role of Nrf2 in the cerebral upregulation of NF‐κB activity, proinflammatory cytokine, and ICAM‐1 after TBI. Wild‐type Nrf2 (+/+) and Nrf2 (−/−)‐deficient mice were subjected to a moderately severe weight‐drop impact head injury. Electrophoretic mobility shift assays (EMSAs) were performed to analyze the activation of nuclear factor kappa B (NF‐κB). Enzyme‐linked immunosorbent assays were performed to quantify the production of tumor necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), and interleukin‐6 (IL‐6). Immunohistochemistry staining experiments were performed to detect the expression of intercellular adhesion molecule‐1 (ICAM‐1). Nrf2 (−/−) mice were shown to have more NF‐κB activation, inflammatory cytokines TNF‐α, IL‐1β and IL‐6 production, and ICAM‐1 expression in brain after TBI compared with their wild‐type Nrf2 (+/+) counterparts. The results suggest that Nrf2 plays an important protective role in limiting the cerebral upregulation of NF‐κB activity, proinflammatory cytokine, and ICAM‐1 after TBI.
Entropy Maximization, Cutoff Distribution, and Finite Stellar Masses
Authors: Dubey Ritesh Kumar , Menon V. J. , Pandey M. K. , Tripathi D. N.
Published: January 2009

Conventional equilibrium statistical mechanics of open gravitational systems is known to be problematical. We first recall that spherical stars/galaxies acquire unbounded radii, become infinitely massive, and evaporate away continuously if one uses the standard Maxwellian distribution fB (which maximizes the usual Boltzmann‐Shannon entropy and hence has a tail extending to infinity). Next, we show that these troubles disappear automatically if we employ the exact most probable distribution f (which maximizes the combinatorial entropy and hence possesses a sharp cutoff tail). Finally, if astronomical observation is carried out on a large galaxy, then the Poisson equation together with thermal de Broglie wavelength provides useful information about the cutoff radius rK, cutoff energy εK, and the huge quantum number K up to which the cluster exists. Thereby, a refinement over the empirical lowered isothermal King models, is achieved. Numerically, we find that the most probable distribution (MPD) prediction fits well the number density profile near the outer edge of globular clusters.
A Review of the “Open” and “Closed” Circulatory Systems: New Terminology for Complex Invertebrate Circulatory Systems in Light of Current Findings
Authors: Reiber Carl L. , McGaw Iain J.
Published: January 2009

Invertebrate cardiovascular systems have historically been viewed as sluggish, poorly regulated, and “open”, where blood bathes the tissues directly as it moves through a system of ill-defined sinuses and/or lacunae without an endothelial boundary. When examining cardiovascular/circulatory morphology and physiology in a broader evolutionary context, one can question the very nature of the definition of a “closed” versus “open” circulatory system. Viewed in this context a number of invertebrates have evolved incomplete or even completely cell-lined vessels and or lacunae with a highly branched vasculature that allows for the production of significant driving pressures and flows to meet relatively high metabolic demands driven by active life styles. In light of our current understanding of invertebrate cardiovascular systems and their paralleled complexity to vertebrate systems, a number of long established paradigms must be questioned and new definitions presented to better align our understanding of the nature of “open” versus “closed” cardiovascular systems.
Severe Hyperlipidemia Induced Hemorrhagic Pancreatitis during Pregnancy
Authors: Koscica Karen L. , Nwaubani Uzoma , Nazir Munir , Gimovsky Martin
Published: January 2009

Background. We report a case of familial hyperlipidemia in pregnancy that resulted in hemorrhagic pancreatitis.Case. A patient at 27-week gestation was admitted for recurrent pancreatitis secondary to severe hyperlipidemia. With conservative care, the patient improved but on the fourth day of admission she experienced a sudden onset of hypotension and was diagnosed with hemorrhagic pancreatitis.Conclusion. Pancreatitis caused by hyperlipidemia is an uncommon event during pregnancy. A familiarity with the severe complications associated with this potentially life-threatening condition is important.
Relationships between Structure, Composition, and Dynamics of the Pristine Northern Boreal Forest and Air Temperature, Precipitation, and Soil Texture in Quebec (Canada)
Authors: Duchesne Louis , Ouimet Rock
Published: January 2009

This study reports on the contemporary structure, composition, and dynamics of the pristine northern boreal forest in Quebec, Canada, associated with air temperature, precipitation, and soil texture, using 147 permanent sample plots located at the limit of continuous forest in Quebec. The results show that tree species composition of stands is associated with stand age, soil texture, air temperature, and precipitation regime. After establishment of the pioneer cohort, the postsuccessional stand dynamics differed among temperature and precipitation regimes, probably because of their influence on tree growth. Our results support the hypothesis that shifts in forest composition related to stand dynamics and the subsequent senescing phase associated with the old growth stage generally occur sooner and proceed faster on more fertile sites due to quicker growth and the subsequent earlier mortality of pioneer species. This study suggests that climate warming should accelerate the successional dynamics of these ecosystems through its positive influence on tree growth.
The Role of Chemotherapy in Upper Tract Urothelial Carcinoma
Authors: O'Donnell Peter H. , Stadler Walter M.
Published: January 2009

Locally advanced upper tract urothelial carcinoma has a poor prognosis. While surgery represents the only potentially curable therapeutic intervention, recurrences are common and typically systemic in nature. It is thus reasonable to consider perioperative chemotherapy in an effort to decrease the risk of recurrence. There are very little direct data providing clinical guidance in this scenario. For urothelial cancer of the bladder, there are randomized phase III data demonstrating a survival advantage with neoadjuvant cisplatin-based combination chemotherapy. Although arguments favoring adjuvant chemotherapy could be made for upper tract urothelial cancer, the loss of renal function that occurs with nephrectomy can complicate administration of appropriate perioperative treatment. Therefore, by analogy to urothelial carcinoma of the lower tract, it is argued that cisplatin-based neoadjuvant chemotherapy should be the standard of care for patients with locally advanced upper tract urothelial cancer.
The Role of the Periaqueductal Gray in the Modulation of Pain in Males and Females: Are the Anatomy and Physiology Really that Different?
Authors: Loyd Dayna R. , Murphy Anne Z.
Published: January 2009

Anatomical and physiological studies conducted in the 1960s identified the periaqueductal gray (PAG) and its descending projections to the rostral ventromedial medulla (RVM) and spinal cord dorsal horn, as a primary anatomical pathway mediating opioid-based analgesia. Since these initial studies, the PAG-RVM-spinal cord pathway has been characterized anatomically and physiologically in a wide range of vertebrate species. Remarkably, the majority of these studies were conducted exclusively in males with the implicit assumption that the anatomy and physiology of this circuit were the same in females; however, this is not the case. It is well established that morphine administration produces greater antinociception in males compared to females. Recent studies indicate that the PAG-RVM pathway contributes to the sexually dimorphic actions of morphine. This manuscript will review our anatomical, physiological, and behavioral data identifying sex differences in the PAG-RVM pathway, focusing on its role in pain modulation and morphine analgesia.