bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Turbulent Flow Structures of a Practical Steady Engine Head Flow Using Large-Eddy Simulations
Authors: Huijnen V. , Somers L. M. T. , Baert R. S. G. , de Goey L. P. H. , Olbricht C. , Sadiki A. , Janicka J.
Published: October 2006

The prediction performance of two computational fluid dynamics codes is compared to each other and to experimental data of a complex swirling and tumbling flow in a practical complex configuration. This configuration consists of a flow in a production-type heavy-duty diesel engine head with 130-mm cylinder bore. One unsteady Reynolds-averaged Navier-Stokes (URANS)-based simulation and two large-eddy simulations (LES) with different inflow conditions have been performed with the KIVA-3V code. Two LES with different resolutions have been performed with the FASTEST-3D code. The parallelization of the this code allows for a more resolved mesh compared to the KIVA-3V code. This kind of simulations gives a complete image of the phenomena that occur in such configurations, and therefore represents a valuable contribution to experimental data. The complex flow structures gives rise to an inhomogeneous turbulence distribution. Such inhomogeneous behavior of the turbulence is well captured by the LES, but naturally damped by the URANS simulation. In the LES, it is confirmed that the inflow conditions play a decisive role for all main flow features. When no particular treatment of the flow through the runners can be made, the best results are achieved by computing a large part of the upstream region, once performed with the FASTEST-3D code. If the inflow conditions are tuned, all main complex flow structures are also recovered by KIVA-3V. The application of upwinding schemes in both codes is in this respect not crucial.
Electro-Osmotic Flow in Reservoir-Connected Flat Microchannels With Non-Uniform Zeta Potential
Authors: Mirbozorgi S. A. , Niazmand H. , Renksizbulut M.
Published: October 2006

The effects of non-uniform zeta potentials on electro-osmotic flows in flat microchannels have been investigated with particular attention to reservoir effects. The governing equations, which consist of a Laplace equation for the distribution of external electric potential, a Poisson equation for the distribution of electric double layer potential, the Nernst-Planck equation for the distribution of charge density, and modified Navier-Stokes equations for the flow field are solved numerically for an incompressible steady flow of a Newtonian fluid using the finite-volume method. For the validation of the numerical scheme, the key features of an ideal electro-osmotic flow with uniform zeta potential have been compared with analytical solutions for the ionic concentration, electric potential, pressure, and velocity fields. When reservoirs are included in the analysis, an adverse pressure gradient is induced in the channel due to entrance and exit effects even when the reservoirs are at the same pressure. Non-uniform zeta potentials lead to complex flow fields, which are examined in detail.
Comparison of Computational Results Obtained From a Homogeneous Cavitation Model With Experimental Investigations of Three Inducers
Authors: Mejri Imene , Bakir Farid , Rey Robert , Belamri Thabet
Published: October 2006

The paper presents full 3D numerical simulations and experimental investigations of the cavitating flow through three axial inducers. These inducers are identified by the tip blade angle at the leading edge β1T=8, 10, and 13deg. The numerical and experimental investigations were carried out at the LEMFI laboratory (Laboratoire d’Energétique et de Mécanique de Fluides Interne) of the ENSAM-Paris center (Ecole Nationale Supérieure d’Arts et Métiers). A review of the cavitating regime modeling and the cavitation homogeneous model used for this paper’s calculations is first presented. The numerical model is based on a combination of the multiphase flow equations with a truncated version of the Rayleigh-Plesset model predicting the complicated growth and collapse processes of bubbles. The mass transfers due to cavitation are source/sink terms in continuity equations of the liquid and vapor phases. The cavitation model also features a solution methodology which implicitly couples the continuity and momentum equations together. The main results are presented for the inducers at a range of flow rates and cavitation numbers: (1) Experimental results concerning: (i) the overall performances: Pressure head coefficient and efficiency versus flow rates; (ii) critical cavitation number (5% and 15% of drop) versus the flow rate; (2) Numerical results concerning: (i) the overall performances; (ii) the numerically investigated water vapor volume fraction distributions and other CFD results, which enable us to explain the cavitating behavior for these inducers; (iii) the location and sizes of the blade cavity and backflow vortex. Finally, the comparisons between experimental and simulated results on the overall performances, cavity sizes and cavity location are discussed. A qualitative agreement between experimental and predicted results was found for two inducers for a range of flow rates. The head breakdown in the simulations started at a different cavitation coefficient than that in the experiment.
Numerical and Experimental Studies of the Flow Field in a Cyclone Dryer
Authors: Bunyawanichakul P. , Kirkpatrick M. P. , Sargison J. E. , Walker G. J.
Published: October 2006

The performance of a newly developed cyclone dryer is investigated using RANS-based single-phase computational fluid dynamics (CFD) and experimental model studies. The cyclone dryer is a cylindrical tower, divided by conical orifices into several chambers; recirculation of the flow within individual chambers ensures adequate retention time for drying of the transported solid material. Numerical calculations are performed using the commercial CFD code CFX5.7 for different mesh types, turbulence models, advection schemes, and mesh resolution. Results of the simulation are compared with data from experimental model studies. The RNG k-ε turbulence model with hexahedral mesh gives satisfactory results. A significant improvement in CFD prediction is obtained when using a second order accurate advection scheme. Useful descriptions of the axial and tangential velocity distributions are obtained, and the pressure drop across the cyclone dryer chamber is predicted with an error of approximately 10%. The optimized numerical model is used to predict the influence of orifice diameter and chamber height on total pressure drop coefficient.
Edge Effects on the Flow Characteristics in a 90deg Tee Junction
Authors: Costa N. P. , Maia R. , Proença M. F. , Pinho F. T.
Published: October 2006

Measurements of pressure drop were carried out for the flow of a Newtonian fluid in 90deg tee junctions with sharp and round corners. Rounding the corners reduced the energy losses by between 10 and 20%, depending on the flow rate ratio, due to the reduction in the branching flow loss coefficient, whereas the straight flow basically remained unaffected. The corresponding detailed measurements of mean and turbulent velocities for a Reynolds number of 31,000 and flowrate ratio of 50% showed that rounding the corner lead to an increase in turbulence in the branch pipe. The increased turbulence diffused momentum more efficiently thus reducing the length of the recirculation by 25% with its width and strength also decreasing in magnitude. The overall effect of the increased dissipation due to turbulence and reduced dissipation due to mean flow irreversibilities in the recirculation was a decrease in the corresponding loss coefficient.
Numerical Simulation of the Fuel Oil Cooling Process in a Wrecked Ship
Authors: Oro Jesús Manuel Fernández , Morros Carlos Santolaria , Díaz Katia María Argüelles , Ybarra Pedro Luis García
Published: October 2006

This work deals with a numerical simulation developed to predict the characteristic cooling times of a low-thermal diffusivity fuel oil confined in the tanks of a wrecked ship. A typical scenario has been introduced through the definition of tank geometries, physical boundary conditions (deep sea temperatures), and rheological properties of the fuel oil. The fluid dynamic behavior of the oil (free convection) inside the tanks, as well as the heat exchange with surrounding sea water has been simulated using a commercial code, FLUENT, which directly solves the Navier-Stokes set of equations, including energy. The purpose is focused on the prediction of both spatial and temporal evolution of the fuel oil characteristic temperature inside the tanks. The objective is to determine the deadline in which the asymptotic temperature curve of the fuel oil converges with deep sea thermal conditions. Inspectional analysis is also outlined, as a powerful tool to predict an order of magnitude in the cooling process.
Nonlinear Control of Variable-Speed Wind Turbines for Generator Torque Limiting and Power Optimization
Authors: Boukhezzar B. , Siguerdidjane H. , Hand M. Maureen
Published: October 2006

To maximize wind power extraction, a variable-speed wind turbine (VSWT) should operate as close as possible to its optimal power coefficient. The generator torque is used as a control input to improve wind energy capture by forcing the wind turbine (WT) to stay close to the maximum energy point. In general, current control techniques do not take into account the dynamical and stochastic aspect of both turbine and wind, leading to significant power losses. In addition, they are not robust with respect to disturbances. In order to address these weaknesses, a nonlinear approach, without wind speed measurement for VSWT control, is proposed. Nonlinear static and dynamic state feedback controllers with wind speed estimator are then derived. The controllers were tested with a WT simple mathematical model and are validated with an aeroelastic wind turbine simulator in the presence of disturbances and measurement noise. The results have shown better performance in comparison with existing controllers.
Common
Kibra
Alleles Are Associated with Human Memory Performance
Authors: Papassotiropoulos Andreas , Stephan Dietrich A. , Huentelman Matthew J. , Hoerndli Frederic J. , Craig David W. , Pearson John V. , Huynh Kim-Dung , Brunner Fabienne , Corneveaux Jason , Osborne David , Wollmer M. Axel , Aerni Amanda , Coluccia Daniel , Hänggi Jürgen , Mondadori Christian R. A. , Buchmann Andreas , Reiman Eric M. , Caselli Richard J. , Henke Katharina , de Quervain Dominique J.-F.
Published: October 2006

Human memory is a polygenic trait. We performed a genome-wide screen to identify memory-related gene variants. A genomic locus encoding the brain protein KIBRA was significantly associated with memory performance in three independent, cognitively normal cohorts from Switzerland and the United States. Gene expression studies showed that
KIBRA
was expressed in memory-related brain structures. Functional magnetic resonance imaging detected
KIBRA
allele–dependent differences in hippocampal activations during memory retrieval. Evidence from these experiments suggests a role for KIBRA in human memory.
Recent Greenland Ice Mass Loss by Drainage System from Satellite Gravity Observations
Authors: Luthcke S. B. , Zwally H. J. , Abdalati W. , Rowlands D. D. , Ray R. D. , Nerem R. S. , Lemoine F. G. , McCarthy J. J. , Chinn D. S.
Published: October 2006

Mass changes of the Greenland Ice Sheet resolved by drainage system regions were derived from a local mass concentration analysis of NASA–Deutsches Zentrum für Luftund Raumfahrt Gravity Recovery and Climate Experiment (GRACE mission) observations. From 2003 to 2005, the ice sheet lost 101 ± 16 gigaton/year, with a gain of 54 gigaton/year above 2000 meters and a loss of 155 gigaton/year at lower elevations. The lower elevations show a large seasonal cycle, with mass losses during summer melting followed by gains from fall through spring. The overall rate of loss reflects a considerable change in trend (–113 ± 17 gigaton/year) from a near balance during the 1990s but is smaller than some other recent estimates.
Exposure to Scientific Theories Affects Women's Math Performance
Authors: Dar-Nimrod Ilan , Heine Steven J.
Published: October 2006

Stereotype threat occurs when stereotyped groups perform worse as their group membership is highlighted. We investigated whether stereotype threat is affected by accounts for the origins of stereotypes. In two studies, women who read of genetic causes of sex differences performed worse on math tests than those who read of experiential causes.
Metamaterial Electromagnetic Cloak at Microwave Frequencies
Authors: Schurig D. , Mock J. J. , Justice B. J. , Cummer S. A. , Pendry J. B. , Starr A. F. , Smith D. R.
Published: October 2006

A recently published theory has suggested that a cloak of invisibility is in principle possible, at least over a narrow frequency band. We describe here the first practical realization of such a cloak; in our demonstration, a copper cylinder was “hidden” inside a cloak constructed according to the previous theoretical prescription. The cloak was constructed with the use of artificially structured metamaterials, designed for operation over a band of microwave frequencies. The cloak decreased scattering from the hidden object while at the same time reducing its shadow, so that the cloak and object combined began to resemble empty space.
HTRA1
Promoter Polymorphism in Wet Age-Related Macular Degeneration
Authors: DeWan Andrew , Liu Mugen , Hartman Stephen , Zhang Samuel Shao-Min , Liu David T. L. , Zhao Connie , Tam Pancy O. S. , Chan Wai Man , Lam Dennis S. C. , Snyder Michael , Barnstable Colin , Pang Chi Pui , Hoh Josephine
Published: October 2006

Age-related macular degeneration (AMD), the most common cause of irreversible vision loss in individuals aged older than 50 years, is classified as either wet (neovascular) or dry (nonneovascular). Inherited variation in the complement factor H gene is a major risk factor for drusen in dry AMD. Here we report that a single-nucleotide polymorphism in the promoter region of
HTRA1
, a serine protease gene on chromosome 10q26, is a major genetic risk factor for wet AMD. A whole-genome association mapping strategy was applied to a Chinese population, yielding a
P
value of <10
–11
. Individuals with the risk-associated genotype were estimated to have a likelihood of developing wet AMD 10 times that of individuals with the wild-type genotype.
Host-Derived Pentapeptide Affecting Adhesion, Proliferation, and Local pH in Biofilm Communities Composed of
Streptococcus
and
Actinomyces
Species
Authors: Drobni Mirva , Li Tong , Krüger Carina , Loimaranta Vuokko , Kilian Mogens , Hammarström Lennart , Jörnvall Hans , Bergman Tomas , Strömberg Nicklas
Published: October 2006

Salivary proline-rich proteins (PRPs) attach commensal
Actinomyces
and
Streptococcus
species to teeth. Here, gel filtration, mass spectrometry and Edman degradation were applied to show the release of a pentapeptide, RGRPQ, from PRP-1 upon proteolysis by
Streptococcus gordonii
. Moreover, synthetic RGRPQ and derivatives were used to investigate associated innate properties and responsible motifs. The RGRPQ peptide increased 2.5-fold the growth rate of
S. gordonii
via a Q-dependent sequence motif and selectively stimulated oral colonization of this organism in a rat model in vivo. In contrast, the growth of
Streptococcus mutans
, implicated in caries, was not affected. While the entire RGRPQ sequence was required to block sucrose-induced pH-decrease by
S. gordonii
and
S. mutans
, the N-terminal Arg residue mediated the pH increase (i.e., ammonia production) by
S. gordonii
alone (which exhibits Arg catabolism to ammonia). Strains of commensal viridans streptococci exhibited PRP degradation and Arg catabolism, whereas cariogenic species did not. The RGRPQ peptide mediated via a differential Q-dependent sequence motif, adhesion inhibition, and desorption of PRP-1-binding strains of
A. naeslundii
genospecies 2 (5 of 10 strains) but not of
S. gordonii
(
n
= 5). The inhibitable
A. naeslundii
strains alone displayed the same binding profile as
S. gordonii
to hybrid peptides terminating in RGRPQ or GQSPQ, derived from the middle or C-terminal segments of PRP-1. The present findings indicate the presence of a host-bacterium interaction in which a host peptide released by bacterial proteolysis affects key properties in biofilm formation.
Schistosoma japonicum
Reinfection after Praziquantel Treatment Causes Anemia Associated with Inflammation
Authors: Leenstra Tjalling , Coutinho Hannah M. , Acosta Luz P. , Langdon Gretchen C. , Su Li , Olveda Remigio M. , McGarvey Stephen T. , Kurtis Jonathan D. , Friedman Jennifer F.
Published: October 2006

There is a relationship between schistosomiasis and anemia, although the magnitude and exact mechanisms involved are unclear. In a cohort of 580
Schistosoma japonicum
-infected 7- to 30-year-old patients from Leyte, The Philippines, we evaluated the impact of reinfection with
S. japonicum
after treatment with praziquantel on the mean hemoglobin level, iron-deficiency (IDA) and non-iron-deficiency anemia (NIDA), and inflammatory markers. All participants were treated at baseline and followed up every 3 months for a total of 18 months. At each follow-up, participants provided stools to quantify reinfection and venous blood samples for hemograms and measures of iron status and inflammation. After 18 months, reinfection with
S. japonicum
was associated with a lower mean hemoglobin level (−0.39 g/dl; 95% confidence interval [95% CI], −0.63 to −0.16) and 1.70 (95% CI, 1.10 to 2.61) times higher odds of all-cause anemia than those without reinfection. Reinfection was associated with IDA for high reinfection intensities only. Conversely, reinfection was associated with NIDA for all infection intensities. Reinfection was associated with serum interleukin-6 responses (
P
< 0.01), and these responses were associated with NIDA (
P
= 0.019) but not with IDA (
P
= 0.29). Our results provide strong evidence for the causal relationship between
S. japonicum
infection and anemia. Rapidly reinfected individuals did not have the positive treatment effect on hemoglobin seen in nonreinfected individuals. The principle mechanism involved in
S. japonicum
-associated anemia is that of proinflammatory cytokine-mediated anemia, with iron deficiency playing a role in high-intensity infections. Based on the proposed mechanism, anemia is unlikely to be ameliorated by iron therapy alone.
Characterization of Host Cell Death Induced byChlamydia trachomatis
Authors: Ying Songmin , Fischer Silke F. , Pettengill Matthew , Conte Debye , Paschen Stefan A. , Ojcius David M. , Häcker Georg
Published: October 2006

Chlamydiaare obligate intracellular bacteria that modulate apoptosis of the host cell. Strikingly, chlamydial infection has been reported both to inhibit and to induce apoptosis. Although the ability to inhibit apoptosis has been corroborated by the identification of cellular targets, confirmation of cell death induction has been complicated by a mixture of apoptotic features and atypical cell death during infection, as well as by differences in the experimental techniques used to measure cell death. Here we use a panel of well-established approaches in the study of apoptosis to define the form of cell death induced byChlamydia trachomatisinfection. Infected cells displayed apoptotic features such as nuclear condensation and fragmentation, as well as positive TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) staining. Fragmentation of genomic DNA occurred, but was atypical. Clear evidence against the activation of effector caspases was found. Nuclear changes were measured in fibroblasts lacking one or both of the effectors of mitochondrial apoptosis, Bax and Bak. A slight reduction in nuclear changes was observed in Bax-deficient cells and in Bax/Bak double-deficient cells. Most surprisingly, this reduction was almost complete in Bak-deficient cells. Finally, dying infected cells were efficiently taken up by professional phagocytes, suggesting thatChlamydia-induced host-cell death could play a role in the immune response. In conclusion, chlamydial infection can induce cell death. AlthoughChlamydia-induced cell death has certain morphological features of apoptosis, it does not result from activation of the apoptotic pathway.
Antigenic Variation of TprK V Regions Abrogates Specific Antibody Binding in Syphilis
Authors: LaFond Rebecca E. , Molini Barbara J. , Van Voorhis Wesley C. , Lukehart Sheila A.
Published: October 2006

ThetprKgene in the syphilis spirochete,Treponema pallidumsubsp.pallidum, undergoes antigenic variation in seven variable (V) regions.tprKis highly variable withinT. pallidumstrains, and a method has been developed to derive clones ofT. pallidumthat express a single, uniquetprKsequence. Rabbits were infected with three differentT. pallidumclones or the parent strain from which the clones were derived, and their sera were examined by immunoassay for antibody reactivity against synthetic peptides representing the TprK V regions from each clone. The parent strain expresses many different V region sequences, and infection with this strain induced antibody responses against a wide variety of V regions. In rabbits infected with the Chicago C clone, antibodies developed against all of the V regions except V1, while antibodies developed against only V5, V6, and V7 in Chicago A-infected rabbits. During Chicago B infection, antibodies developed against all of the V regions except V1 and V3. Antibodies were highly specific for the V regions of the infecting clone, and cross-reactivity was rare. The demonstration that the V regions elicit a variant-specific antibody response supports the hypothesis that TprK variants may help organisms to avoid the developing immune response in infected individuals, contributing to the ability ofT. pallidumto establish chronic infection.
Aberrant Contraction of Antigen-Specific CD4 T Cells after Infection in the Absence of Gamma Interferon or Its Receptor
Authors: Haring Jodie S. , Harty John T.
Published: October 2006

Several lines of evidence from different model systems suggest that gamma interferon (IFN-γ) is an important regulator of T-cell contraction after antigen (Ag)-driven expansion. To specifically investigate the role of IFN-γ in regulating the contraction of Ag-specific CD4 T cells, we infected IFN-γ
−/−
and IFN-γR1
−/−
mice with attenuated
Listeria monocytogenes
and monitored the numbers of Ag-specific CD4 T cells during the expansion, contraction, and memory phases of the immune response to infection. In the absence of IFN-γ or the ligand-binding portion of its receptor, Ag-specific CD4 T cells exhibited normal expansion in numbers, but in both strains of deficient mice there was very little decrease in the number of Ag-specific CD4 T cells even at time points later than day 90 after infection. This significant delay in contraction was not due to prolonged infection, since mice treated with antibiotics to conclusively eliminate infection exhibited the same defect in contraction. In addition to altering the number of Ag-specific CD4 T cells, the absence of IFN-γ signaling also changed the phenotype of cells generated after infection. IFN-γR1
−/−
Ag-specific CD4 T cells reacquired expression of CD127 more quickly than wild-type cells, and more IFN-γR1
−/−
CD4 T cells were capable of producing both IFN-γ and interleukin 2 following Ag stimulation. From these data we conclude that IFN-γ regulates the contraction, phenotype, and function of Ag-specific CD4 T cells generated after infection.
Hierarchy of Iron Uptake Systems: Yfu and Yiu Are Functional in
Yersinia pestis
Authors: Kirillina Olga , Bobrov Alexander G. , Fetherston Jacqueline D. , Perry Robert D.
Published: October 2006

In addition to the yersiniabactin (Ybt) siderophore-dependent system, two inorganic iron ABC transport systems of
Yersinia pestis
, Yfe and Yfu, have been characterized. Here we show that the Yfu system functions in
Y. pestis
: a Ybt
−
Yfe
−
Yfu
−
mutant exhibited a greater growth defect under iron-deficient conditions than its Ybt
−
Yfe
−
parental strain. We also demonstrate that another putative
Y. pestis
iron uptake system, Yiu, which potentially encodes an outer membrane receptor, YiuR, and an ABC iron transport cassette, YiuABC, is functional. The cloned
yiuABC
operon restored growth of an enterobactin-deficient mutant
Escherichia coli
strain, 1017, under iron-chelated conditions. Iron uptake by the Yiu system in
Y. pestis
was demonstrated only when the Ybt, Yfe, and Yfu systems were mutated. Using a
yiuA
::
lacZ
fusion, we show that the
yiuABC
promoter is repressed by iron through Fur. A mouse model of bubonic plague failed to show a significant role for the Yiu system in the disease process. These results demonstrate that two additional iron transporters are functional in
Y. pestis
and indicate that there is a hierarchy of iron transporters, with Ybt being most effective and Yiu being the least effective of those systems which have been characterized.
Role of Inducible Nitric Oxide Synthase and NADPH Oxidase in Early Control ofBurkholderia pseudomalleiInfection in Mice
Authors: Breitbach Katrin , Klocke Sonja , Tschernig Thomas , van Rooijen Nico , Baumann Ulrich , Steinmetz Ivo
Published: October 2006

Infection with the soil bacteriumBurkholderia pseudomalleican result in a variety of clinical outcomes, including asymptomatic infection. The initial immune defense mechanisms which might contribute to the various outcomes after environmental contact withB. pseudomalleiare largely unknown. We have previously shown that relatively resistant C57BL/6 mice can restrict bacterialB. pseudomalleigrowth more efficiently within 1 day after infection than highly susceptible BALB/c mice. By using this model, our study aimed to investigate the role of macrophage-mediated effector mechanisms during earlyB. pseudomalleiinfection. Depletion of macrophages revealed an essential role of these cells in the early control of infection in BALB/c and C57BL/6 mice. Strikingly, the comparison of the anti-B. pseudomalleiactivity of bone marrow-derived macrophages (BMM) from C57BL/6 and BALB/c mice revealed an enhanced bactericidal activity of C57BL/6 BMM, particularly after gamma interferon (IFN-γ) stimulation. In vitro experiments with C57BL/6gp91phox−/−BMM showed an impaired intracellular killing ofB. pseudomalleicompared to experiments with wild-type cells, although C57BL/6gp91phox−/−cells still exhibited substantial killing activity. The anti-B. pseudomalleiactivity of C57BL/6iNOS−/−BMM was not impaired. C57BL/6gp91phox−/−mice lacking a functional NADPH oxidase were more susceptible to infection, whereas C57BL/6 mice lacking inducible nitric oxide synthase (iNOS) did not show increased susceptibility but were slightly more resistant during the early phase of infection. Thus, our data suggest that IFN-γ-mediated but iNOS-independent anti-B. pseudomalleimechanisms of macrophages might contribute to the enhanced resistance of C57BL/6 mice compared to that of BALB/c mice in the early phase of infection.
Cryptococcus neoformans
Cells in Biofilms Are Less Susceptible than Planktonic Cells to Antimicrobial Molecules Produced by the Innate Immune System
Authors: Martinez Luis R. , Casadevall Arturo
Published: October 2006

The human pathogenic fungus
Cryptococcus neoformans
can form biofilms on polystyrene plates and medical devices in a process that requires capsular polysaccharide release. Although biofilms are known to be less susceptible to antimicrobial drugs, little is known about their susceptibility to antimicrobial molecules produced by the innate immune system. In this study, we investigated the susceptibility of
C. neoformans
cells in biofilm and planktonic states to oxidative and nonoxidative antimicrobial molecules produced by phagocytic cells. The effects of various immune effector molecules on the fungal mass, metabolic activity, and architecture of
C. neoformans
biofilms were measured by colony counts, 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide reduction, and confocal microscopy, respectively. Biofilms were more resistant than planktonic cells to oxidative stress but remained vulnerable to cationic antimicrobial peptides. However, melanized biofilms were significantly less susceptible to antimicrobial peptides than nonmelanized biofilms. These results suggest that the biofilm phenotype increases resistance against host immune mechanisms, a phenomenon that could contribute to the ability of biofilm-forming microbes to establish persistent infections.
Role for Matrix Metalloproteinase 9 in Granuloma Formation during PulmonaryMycobacterium tuberculosisInfection
Authors: Taylor Jennifer L. , Hattle Jessica M. , Dreitz Steven A. , Troudt JoLynn M. , Izzo Linda S. , Basaraba Randall J. , Orme Ian M. , Matrisian Lynn M. , Izzo Angelo A.
Published: October 2006

Recent studies have shown that matrix metalloproteinases (MMPs) are induced byMycobacterium tuberculosisduring pulmonary infection. Here, expression of MMP-9 during pulmonaryM. tuberculosisinfection was characterized to determine whether its production correlated with disease resistance in vivo and to determine what role, if any, MMP-9 might have in granuloma formation. Following aerosol infection withM. tuberculosis, dissemination of bacilli occurred earlier in the C57BL/6 resistant mouse strain than in the susceptible CBA/J strain, as was evident from an increased number of bacteria in the blood, spleen, and liver at day 14 after infection. In addition, early dissemination of the bacilli was associated with early induction of protective immunity as assessed from gamma interferon levels. Nonspecific blocking of MMPs in C57BL/6 mice early during infection reduced hematogenous spread of the bacilli, suggesting that MMPs indeed play a role in facilitating dissemination, likely via extracellular matrix degradation. The concentration of active MMP-9, specifically, was greater in the lungs of C57BL/6 mice than in those of the CBA/J mice at day 28, thereby suggesting that MMP-9 is not one of the MMPs directly involved in promoting early dissemination ofM. tuberculosis. Instead, however, histological lung sections and flow cytometric analysis of lung cells from MMP-9-knockout mice showed that MMP-9 is involved in macrophage recruitment and granuloma development. These combined data support the idea that early MMP activity is an essential component of resistance to pulmonary mycobacterial infection and that MMP-9, specifically, is required for recruitment of macrophages and tissue remodeling to allow for the formation of tight, well-organized granulomas.
Comparison of two indices of exposure to polycyclic aromatic hydrocarbons in a retrospective aluminium smelter cohort
Authors: Friesen Melissa C , Demers Paul A , Spinelli John J , Lorenzi Maria F , Le Nhu D
Published: October 2006

Background:The association between coal tar-derived substances, a complex mixture of polycyclic aromatic hydrocarbons, and cancer is well established. However, the specific aetiological agents are unknown.

Objective:To compare the dose–response relationships for two common measures of coal tar-derived substances, benzene-soluble material (BSM) and benzo(a)pyrene (BaP), and to evaluate which among these is more strongly related to the health outcomes.

Methods:The study population consisted of 6423 men with ⩾3 years of work experience at an aluminium smelter (1954–97). Three health outcomes identified from national mortality and cancer databases were evaluated: incidence of bladder cancer (n = 90), incidence of lung cancer (n = 147) and mortality due to acute myocardial infarction (AMI, n = 184). The shape, magnitude and precision of the dose–response relationships and cumulative exposure levels for BSM and BaP were evaluated. Two model structures were assessed, where 1n(relative risk) increased with cumulative exposure (log-linear model) or with log-transformed cumulative exposure (log–log model).

Results:The BaP and BSM cumulative exposure metrics were highly correlated (r = 0.94). The increase in model precision using BaP over BSM was 14% for bladder cancer and 5% for lung cancer; no difference was observed for AMI. The log-linear BaP model provided the best fit for bladder cancer. The log–log dose–response models, where risk of disease plateaus at high exposure levels, were the best-fitting models for lung cancer and AMI.

Conclusion:BaP and BSM were both strongly associated with bladder and lung cancer and modestly associated with AMI. Similar conclusions regarding the associations could be made regardless of the exposure metric.
ELECTRICAL RESISTIVITY AND AC SUSCEPTIBILITY STUDIES IN Sr1-xLaxMnO3
Authors: KAR MANORANJAN , RAVI S.
Published: October 2006

Electron-doped Sr 1-x La x MnO 3(0≤x≤0.50) and hole-doped (x=0.70 and 0.82) samples have been prepared by solid state route. X-ray diffraction patterns could be refined using P63 space group for x≤0.30 and [Formula: see text] space group for x≥0.40. Temperature variation of AC susceptibility measurements show that all the electron-doped materials exhibit paramagnetic to ferromagnetic transitions with the transition temperatures ranging from 375 to 393 K, followed by low temperature antiferromagnetic transitions. The ferromagnetic maximum susceptibility is found to increase systematically with La doping, i.e. with increase in Mn 3+ ions. The high temperature resistivity data could be analyzed using the Mott-variable range hopping model. The hole-doped materials exhibit ferromagnetic to paramagnetic transition.
EFFECT OF OXYGEN DOPING IN ab-PLANE OF Bi2Sr2CaCu2Oy THIN FILMS GROWN ON VICINAL SrTiO3 SUBSTRATES: PSEUDOGAP EFFECT
Authors: TOMA V. , ILONCA G. , RAFFY H.
Published: October 2006

The in-plane resistivity ρab(T) are measured for Bi 2 Sr 2 CaCu 2 O 8 superconducting thin films successfully deposited by in situ magnetron RF-sputtering on vicinal (100) SrTiO 3 substrates. Oriented film with c-axis inclined with respect to the basal plane by a tilt angle α≈4° was obtained. The oxygen content of the film was changed from the maximally overdoped state to strongly underdoped nonsuperconducting states. It was found that for underdoped and overdoped regions ρab(T) deviates from the high T-linear behavior at characteristic temperatures T* and T**.
A NEW ANALYTICAL APPROXIMATION FORMULA FOR THE OPTIMAL EXERCISE BOUNDARY OF AMERICAN PUT OPTIONS
Authors: ZHU SONG-PING
Published: October 2006

In this paper, a new analytical formula as an approximation to the value of American put options and their optimal exercise boundary is presented. A transform is first introduced to better deal with the terminal condition and, most importantly, the optimal exercise price which is an unknown moving boundary and the key reason that valuing American options is much harder than valuing its European counterparts. The pseudo-steady-state approximation is then used in the performance of the Laplace transform, to convert the systems of partial differential equations to systems of ordinary differential equations in the Laplace space. A simple and elegant formula is found for the optimal exercise boundary as well as the option price of the American put with constant interest rate and volatility. Other hedge parameters as the derivatives of this solution are also presented.
STUDY OF VOLUME VARIATION OF IMPLICIT OBJECTS
Authors: FAUDOT DOMINIQUE , GESQUIERE GILLES
Published: October 2006

We propose studying the variations of volume of implicit objects during an animation according to several points of view: choice of the function of density, variations of parameters such as the iso-value and the radius of influence for a given function, variations of the parameters inherent in a particular function. Modification of parameters of the function of density must be carried out with care. There are no rules concerning these variations. To avoid the non-monotonous variations, it is necessary to choose a function of density beforehand and study the intervals of variation of its parameters. A new discretization makes it possible to locate these variations for a later use in a process of control of these variations.
HUMAN MOTION PERCEPTION THROUGH VIDEO MODEL-BASED TRACKING
Authors: DE LA RIVIÈRE JEAN-BAPTISTE , GUITTON PASCAL
Published: October 2006

As computer vision enables the robot to be aware of its human counterpart, such algorithms could help machines to achieve human-like interaction. However, many video tracking algorithms are not able to cope with some robot vision requirements. The articulated tracking system we develop solves some of those issues. It relies on model-based algorithms, which we believe are more suitable to robot vision than appearance-based ones. Indeed, as they update all the relevant parameters of a surrounding world model, results include some knowledge of the camera and objects relative positions. Our system relies on 3D model silhouette matching and runs in real time. We increase the algorithm robustness by introducing a pre-processing step based on image moments. This allows the iteration refinement to start in a better position by roughly estimating the body motion from one frame to the next.
FEATURE FUSION AND MODEL SELECTION BASED ON INFORMATION CRITERION
Authors: SATONAKA TAKAMI , UCHIMURA KEIICHI
Published: October 2006

We describe the k-NN adaptive metric learning procedure combining the asymptotic variance estimation and fine adjustment of the metric parameters for the face recognition. The metric learning model based on the Mahalanobis distance suffered from the degraded performance due to the limitation of available training samples. The feature fusion methods are proposed to assume local distributions of feature patterns for the parameter estimation and learning. Firstly, the MDL criterion is formulated to decide on the trade-offs between accuracy and complexity of an asymptotic statistical model. The variance within the classes is minimized by using the asymptotic variance estimation. Secondly, optimal metric parameters are derived from the minimization of the negative log-likelihood function for the presentation of the synthesized feature patterns. The variance between the classes is increased by using the simulated annealing method. We present the simulation results using the ORL and UMIST databases.
Targeting VEGF-A to Treat Cancer and Age-Related Macular Degeneration
Authors: Ferrara Napoleone , Mass Robert D. , Campa Claudio , Kim Robert
Published: October 2006

Inhibiting angiogenesis is a promising strategy to treat cancer and several other disorders, including intraocular neovascular syndromes. The identification of vascular endothelial growth factor (VEGF)-A as a major regulator of normal and pathological angiogenesis has enabled significant progress toward effective treatments for such disorders. Several VEGF inhibitors have been recently approved by the U.S. Food and Drug Administration for the treatment of cancer and the neovascular form of age-related macular degeneration. This review summarizes the basic biology of VEGF-A and illustrates the clinical progress in targeting this molecule.
Peripheral versus central modulation of gastric vagal pathways by metabotropic glutamate receptor 5
Authors: Young Richard L. , Page Amanda J. , O'Donnell Tracey A. , Cooper Nicole J. , Blackshaw L. Ashley
Published: October 2006

Metabotropic glutamate receptors (mGluR) are classified into group I, II, and III mGluR. Group I (mGluR1, mGluR5) are excitatory, whereas group II and III are inhibitory. mGluR5 antagonism potently reduces triggering of transient lower esophageal sphincter relaxations and gastroesophageal reflux. Transient lower esophageal sphincter relaxations are mediated via a vagal pathway and initiated by distension of the proximal stomach. Here, we determined the site of action of mGluR5 in gastric vagal pathways by investigating peripheral responses of ferret gastroesophageal vagal afferents to graded mechanical stimuli in vitro and central responses of nucleus tractus solitarius (NTS) neurons with gastric input in vivo in the presence or absence of the mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP). mGluR5 were also identified immunohistochemically in the nodose ganglia and NTS after extrinsic vagal inputs had been traced from the proximal stomach. Gastroesophageal vagal afferents were classified as mucosal, tension, or tension-mucosal (TM) receptors. MPEP (1–10 μM) inhibited responses to circumferential tension of tension and TM receptors. Responses to mucosal stroking of mucosal and TM receptors were unaffected. MPEP (0.001–10 nmol icv) had no major effect on the majority of NTS neurons excited by gastric distension or on NTS neurons inhibited by distension. mGluR5 labeling was abundant in gastric vagal afferent neurons and sparse in fibers within NTS vagal subnuclei. We conclude that mGluR5 play a prominent role at gastroesophageal vagal afferent endings but a minor role in central gastric vagal pathways. Peripheral mGluR5 may prove a suitable target for reducing mechanosensory input from the periphery, for therapeutic benefit.
Early skeletal muscle hypertrophy and architectural changes in response to high-intensity resistance training
Authors: Seynnes O. R. , de Boer M. , Narici M. V.
Published: October 2006

The onset of whole muscle hypertrophy in response to overloading is poorly documented. The purpose of this study was to assess the early changes in muscle size and architecture during a 35-day high-intensity resistance training (RT) program. Seven young healthy volunteers performed bilateral leg extension three times per week on a gravity-independent flywheel ergometer. Cross-sectional area (CSA) in the central (C) and distal (D) regions of the quadriceps femoris (QF), muscle architecture, maximal voluntary contraction (MVC), and electromyographic (EMG) activity were measured before and after 10, 20, and 35 days of RT. By the end of the training period, MVC and EMG activity increased by 38.9 ± 5.7 and 34.8% ± 4.7%, respectively. Significant increase in QF CSA (3.5 and 5.2% in the C and D regions, respectively) was observed after 20 days of training, along with a 2.4 ± 0.7% increase in fascicle length from the 10th day of training. By the end of the 35-day training period, the total increase in QF CSA for regions C and D was 6.5 ± 1.1 and 7.4 ± 0.8%, respectively, and fascicle length and pennation angle increased by 9.9 ± 1.2 and 7.7 ± 1.3%, respectively. The results show for the first time that changes in muscle size are detectable after only 3 wk of RT and that remodeling of muscle architecture precedes gains in muscle CSA. Muscle hypertrophy seems to contribute to strength gains earlier than previously reported; flywheel training seems particularly effective for inducing these early structural adaptations.
Space–Time Relativity in Self-Motion Reproduction
Authors: Glasauer Stefan , Schneider Erich , Grasso Renato , Ivanenko Yuri P.
Published: October 2006

Experiments on reproducing imposed self-motion showed that not only final distance or angle of motion, but also the temporal profile are reproduced. Reproduction errors have been attributed to sensory inputs, inaccurate memorization of the motion variable, or motor errors. However, another possible source of error has so far been neglected. The internal time base for path integration or movement memorization may be distorted and thus not reflect physical time. Because additional cognitive load was previously shown to affect subjective estimation of duration, we used a dual-task paradigm during either the stimulation or reproduction phase of three different movement reproduction tasks. We asked subjects 1) on a rotating chair to reproduce imposed passive whole body rotations by controlling the chair with a joystick, 2) on a treadmill to actively reproduce locomotion with respect to the treadmill, and 3) while blindfolded to reproduce a previously walked straight trajectory. The cognitive load changed the distance of reproduced self-motion by about 25% depending on whether the mental task was performed while experiencing or reproducing the motion. Although imposed velocity was reproduced accurately in all conditions, reproduced movement duration was affected in the same way as distance. This result implies that for the perception of distance traveled, perceptual space and time are closely interrelated. The findings are consistent with shared processing of temporal and spatial information. A computational model of motion reproduction including a discrete path integrator is proposed that is able to explain the experimental results within one coherent framework.
A Composite Molecular Phylogeny of Living Lemuroid Primates
Authors: DelPero Massimiliano , Pozzi Luca , Masters Judith C.
Published: October 2006

Lemuroid phylogeny is a source of lively debate among primatologists. Reconstructions based on morphological, physiological, behavioural and molecular data have yielded a diverse array of tree topologies with few nodes in common. In the last decade, molecular phylogenetic studies have grown in popularity, and a wide range of sequences has been brought to bear on the problem, but consensus has remained elusive. We present an analysis based on a composite molecular data set of approx. 6,400 bp assembled from the National Center for Biotechnology Information (NCBI) database, including both mitochondrial and nuclear genes, and diverse analytical methods. Our analysis consolidates some of the nodes that were insecure in previous reconstructions, but is still equivocal on the placement of some taxa. We conducted a similar analysis of a composite data set of approx. 3,600 bp to investigate the controversial relationships within the family Lemuridae. Here our analysis was more successful; only the position of Eulemur coronatus remained uncertain.
Lucid Dreaming Treatment for Nightmares: A Pilot Study
Authors: Spoormaker Victor I. , van den Bout Jan
Published: October 2006

Background: The goal of this pilot study was to evaluate the effects of the cognitive-restructuring technique ‘lucid dreaming treatment’ (LDT) on chronic nightmares. Becoming lucid (realizing that one is dreaming) during a nightmare allows one to alter the nightmare storyline during the nightmare itself. Methods: After having filled out a sleep and a posttraumatic stress disorder questionnaire, 23 nightmare sufferers were randomly divided into 3 groups; 8 participants received one 2-hour individual LDT session, 8 participants received one 2-hour group LDT session, and 7 participants were placed on the waiting list. LDT consisted of exposure, mastery, and lucidity exercises. Participants filled out the same questionnaires 12 weeks after the intervention (follow-up). Results: At follow-up the nightmare frequency of both treatment groups had decreased. There were no significant changes in sleep quality and posttraumatic stress disorder symptom severity. Lucidity was not necessary for a reduction in nightmare frequency. Conclusions: LDT seems effective in reducing nightmare frequency, although the primary therapeutic component (i.e. exposure, mastery, or lucidity) remains unclear.