bluuebunny/crossref_metadata_2025 huggingface dataset:
Computations for Unsteady Compressible Flows in a Multistage Steam Turbine With Steam Properties at Low Load Operations
Authors: Senoo Shigeki , Segawa Kiyoshi , Hamatake Hisashi , Kudo Takeshi , Nakamura Tateki , Shibashita Naoaki
Published: May 2011

A computational technique for multistage steam turbines, which can allow for thermodynamic properties of steam, is presented. Conventional three-dimensional multistage calculations for unsteady flows have two main problems. One is the long computation time and the other is how to include the thermodynamic properties of steam. Ideal gas is assumed in most computational techniques for compressible flows. To shorten the computational time, a quasi-three-dimensional flow calculation technique is developed. In the analysis, conservation laws for compressible fluid in axisymmetric cylindrical coordinates are solved using a finite volume method based on an approximate Riemann solver. Blade forces are calculated from the camber and lean angles of blades with momentum equations. The axisymmetric assumption and the blade force model enable the effective calculation for multistage flows, even when the flow is strongly unsteady under off-design conditions. To take into account steam properties including effects of the gas-liquid phase change and two-phase flow, a flux-splitting procedure of compressible flow is generalized for real fluid. Density and internal energy per unit volume are selected as independent thermodynamic variables. Pressure and temperature in a superheated region or wetness mass fraction in a wet region are calculated by using a steam table. To improve computational efficiency, a discretized steam table matrix is made in which the density and specific internal energy are independent variables. For accuracy and continuity of steam properties, the second order Taylor expansion and linear interpolation are introduced. The computed results of the last four-stage low-pressure steam turbine at low load conditions show that there is a reverse flow near the hub region of the last stage bucket and the flow concentrates in the tip region due to the centrifugal force. At a very low load condition, the reverse flow region extends to the former stages and the unsteadiness of flow gets larger due to many vortices. Four-stage low-pressure steam turbine tests are also carried out at low load. The radial distributions of flow direction downstream from each stage are measured by traversing pneumatic probes. Additionally, pressure transducers are installed in the side wall to measure unsteady pressure. The regions of reverse flow are compared between computations and experiments at different load conditions, and their agreement is good. Further, the computation can follow the trends of standard deviation of unsteady pressure on the wall to volumetric flow rate of experiments.
Mechanism of Impaired NLRP3 Inflammasome Priming by Monophosphoryl Lipid A
Authors: Embry Chelsea A. , Franchi Luigi , Nuñez Gabriel , Mitchell Thomas C.
Published: May 2011

Biased signaling by an immune receptor ligand underlies its inability to induce inflammatory responses.
Notch on a Sugar High
Authors: VanHook Annalisa M.
Published: May 2011

O
-glucosylation modulates the activity of mammalian Notch.
Induction of Efflux-Mediated Macrolide Resistance in Streptococcus pneumoniae
Authors: Chancey Scott T. , Zhou Xiaoliu , Zähner Dorothea , Stephens David S.
Published: May 2011

The antimicrobial efflux system encoded by the operon
mef(E)-mel
on the mobile genetic element MEGA in
Streptococcus pneumoniae
and other Gram-positive bacteria is inducible by macrolide antibiotics and antimicrobial peptides. Induction may affect the clinical response to the use of macrolides. We developed
mef(E)
reporter constructs and a disk diffusion induction and resistance assay to determine the kinetics and basis of
mef(E)-mel
induction. Induction occurred rapidly, with a >15-fold increase in transcription within 1 h of exposure to subinhibitory concentrations of erythromycin. A spectrum of environmental conditions, including competence and nonmacrolide antibiotics with distinct cellular targets, did not induce
mef(E).
Using 16 different structurally defined macrolides, induction was correlated with the amino sugar attached to C-5 of the macrolide lactone ring, not with the size (e.g., 14-, 15- or 16-member) of the ring or with the presence of the neutral sugar cladinose at C-3. Macrolides with a monosaccharide attached to C-5, known to block exit of the nascent peptide from the ribosome after the incorporation of up to eight amino acids, induced
mef(E)
expression. Macrolides with a C-5 disaccharide, which extends the macrolide into the ribosomal exit tunnel, disrupting peptidyl transferase activity, did not induce it. The induction of
mef(E)
did not require macrolide efflux, but the affinity of macrolides for the ribosome determined the availability for efflux and pneumococcal susceptibility. The induction of
mef(E)-mel
expression by inducing macrolides appears to be based on specific interactions of the macrolide C-5 saccharide with the ribosome that alleviate transcriptional attenuation of
mef(E)-mel.
Diversity and Evolution of AbaR Genomic Resistance Islands in Acinetobacter baumannii Strains of European Clone I
Authors: Krizova Lenka , Dijkshoorn Lenie , Nemec Alexandr
Published: May 2011

To assess the diversity of AbaR genomic resistance islands in
Acinetobacter baumannii
European clone I (MLST clonal complex 1), we investigated 26 multidrug-resistant strains of this major clone isolated from hospitals in 21 cities of 10 European countries between 1984 and 2005. Each strain harbored an AbaR structure integrated at the same position in the chromosomal ATPase gene. AbaR3, including four subtypes based on variations in class 1 integron cassettes, and AbaR10 were found in 15 and 2 strains, respectively, whereas a new, unique AbaR variant was discovered in each of the other 9 strains. These new variants, designated AbaR11 to AbaR19 (19.8 kb to 57.5 kb), seem to be truncated derivatives of AbaR3, likely resulting from the deletions of its internal parts mediated by either IS
26
elements (AbaR12 to AbaR19) or homologous recombination (AbaR11). AbaR3 was detected in all 10 strains isolated in 1984 to 1991, while AbaR11 to AbaR19 were carried only by strains isolated since 1997. Our results and those from previous publications suggest that AbaR3 is the original form of AbaR in European clone I, which may have provided strains of the lineage with a selective advantage facilitating their spread in European hospitals in the 1980s or before.
Effects of Altering Aminoglycoside Structures on Bacterial Resistance Enzyme Activities
Authors: Green Keith D. , Chen Wenjing , Garneau-Tsodikova Sylvie
Published: May 2011

Aminoglycoside-modifying enzymes (AMEs) constitute the most prevalent mechanism of resistance to aminoglycosides by bacteria. We show that aminoglycosides can be doubly modified by the sequential actions of AMEs, with the activity of the second AME in most cases unaffected, decreased, or completely abolished. We demonstrate that the bifunctional enzyme AAC(3)-Ib/AAC(6′)-Ib′ can diacetylate gentamicin. Since single acetylation does not always inactivate the parent drugs completely, two modifications likely provide more-robust inactivation
in vivo
.
Protein Binding: Do We Ever Learn?
Authors: Zeitlinger Markus A. , Derendorf Hartmut , Mouton Johan W. , Cars Otto , Craig William A. , Andes David , Theuretzbacher Ursula
Published: May 2011

Although the influence of protein binding (PB) on antibacterial activity has been reported for many antibiotics and over many years, there is currently no standardization for pharmacodynamic models that account for the impact of protein binding of antimicrobial agentsin vitro. This might explain the somewhat contradictory results obtained from different studies. Simplein vitromodels which compare the MIC obtained in protein-free standard medium versus a protein-rich medium are prone to methodological pitfalls and may lead to flawed conclusions. Withinin vitrotest systems, a range of test conditions, including source of protein, concentration of the tested antibiotic, temperature, pH, electrolytes, and supplements may influence the impact of protein binding. As new antibiotics with a high degree of protein binding are in clinical development, attention and action directed toward the optimization and standardization of testing the impact of protein binding on the activity of antibioticsin vitrobecome even more urgent. In addition, the quantitative relationship between the effects of protein bindingin vitroandin vivoneeds to be established, since the physiological conditions differ. General recommendations for testing the impact of protein bindingin vitroare suggested.
In Vitro
Activity of Ceftazidime-NXL104 against 396 Strains of β-Lactamase-Producing Anaerobes
Authors: Citron Diane M. , Tyrrell Kerin L. , Merriam Vreni , Goldstein Ellie J. C.
Published: May 2011

NXL104, a novel β-lactamase inhibitor, was tested at a constant concentration of 4 μg/ml in combination with ceftazidime (CAZ), with and without added metronidazole, against 396 β-lactamase-producing strains of anaerobic bacteria. MIC
50
/MIC
90
values for
Bacteroides fragilis
and the
B. fragilis
group were 8/16 and 64/>128 μg/ml, respectively. Although CAZ-NXL104 had limited activity against most anaerobic strains, in combination with metronidazole it shows potential for treating mixed infections involving resistant
Enterobacteriaceae
and anaerobes.
Efficacy of Caspofungin in Neutropenic and Corticosteroid-Immunosuppressed Murine Models of Invasive Pulmonary Mucormycosis
Authors: Lewis Russell E. , Leventakos Konstantinos , Liao Guangling , Kontoyiannis Dimitrios P.
Published: May 2011

Caspofungin (CFG) was tested in neutropenic and corticosteroid-immunosuppressed mice challenged with a lethal sinopulmonary inoculum of
Rhizopus oryzae
. Compared to untreated controls, CFG administered at 1 mg/kg of body weight/day significantly improved survival (54% versus 19%;
P
= 0.003) and reduced median
R. oryzae
fungal burden by 1.5 log
10
for conidial equivalent DNA in neutropenic but not corticosteroid-immunosuppressed animals. CFG administered at 16 mg/kg/day was not significantly better than a saline control for treatment of invasive pulmonary mucormycosis (IPM) in either neutropenic or corticosteroid-immunosuppressed animals.
Trimeric Autotransporter Adhesin-Dependent Adherence of Bartonella henselae, Bartonella quintana, and Yersinia enterocolitica to Matrix Components and Endothelial Cells under Static and Dynamic Flow Conditions
Authors: Müller Niklas F. , Kaiser Patrick O. , Linke Dirk , Schwarz Heinz , Riess Tanja , Schäfer Andrea , Eble Johannes A. , Kempf Volkhard A. J.
Published: May 2011

Trimeric autotransporter adhesins (TAAs) are important virulence factors of Gram-negative bacteria responsible for adherence to extracellular matrix (ECM) and host cells. Here, we analyzed three different TAAs (
Bartonella
adhesin A [BadA] of
Bartonella henselae
, variably expressed outer membrane proteins [Vomps] of
Bartonella quintana
, and
Yersinia
adhesin A [YadA] of
Yersinia enterocolitica
) for mediating bacterial adherence to ECM and endothelial cells. Using static (cell culture vials) and dynamic (capillary flow chambers) experimental settings, adherence of wild-type bacteria and of the respective TAA-negative strains was analyzed. Under static conditions, ECM adherence of
B. henselae
,
B. quintana
, and
Y. enterocolitica
was strongly dependent on the expression of their particular TAAs. YadA of
Y. enterocolitica
did not mediate bacterial binding to plasma or cellular fibronectin under either static or dynamic conditions. TAA-dependent host cell adherence appeared more significant under dynamic conditions although the total number of bound bacteria was diminished compared to the number under static conditions. Dynamic models expand the methodology to perform bacterial adherence experiments under more realistic, bloodstream-like conditions and allow dissection of the biological role of TAAs in ECM and host cell adherence under static and dynamic conditions.
Fusobacterium nucleatum Infection of Colonic Cells Stimulates MUC2 Mucin and Tumor Necrosis Factor Alpha
Authors: Dharmani Poonam , Strauss Jaclyn , Ambrose Christian , Allen-Vercoe Emma , Chadee Kris
Published: May 2011

The etiology of inflammatory bowel disease is not completely known, but it is influenced by the presence of normal gut microflora as well as yet-unrecognized pathogens. The anaerobic, Gram-negative bacterial speciesFusobacterium nucleatumis a common resident of the human mouth and gut and varies in its pathogenic potential. In this study, we demonstrate that highly invasiveF. nucleatumisolates derived from the inflamed guts of Crohn's disease patients evoked significantly greater MUC2 and tumor necrosis factor alpha (TNF-α) gene expression than minimally invasive strains isolated from the noninflamed gut in human colonic epithelial cells and in a rat ligated colonic loop model of infection. Only liveF. nucleatuminduced mucin secretion and TNF-α expression in direct contact with and/or during invasion of colonic cells. In rat colons, mucin secretion was augmented in response to a highly invasiveF. nucleatumisolate but was unaffected by treatment with a minimally invasive strain. Taken together, these studies reveal thatF. nucleatummay represent a challenging pathogen in the etiology of gut inflammatory diseases and highlight the importance of different pathotypes of candidate bacterial species in disease pathogenesis.
Vibrational dynamics of adsorbed CO2: Separability of the CO2 asymmetric stretching mode
Authors: Bludský Ota , Nachtigall Petr , Špirko Vladimír
Published: May 2011

Separability of the CO2 asymmetric stretching mode is probed theoretically by performing highly accurate vibrational calculations on the CO2 and K+CO2 model systems. The proposed approach is applied to a model case of the vibrational dynamics of the CO2 molecule adsorbed in K-FER zeolite. The CCSD(T) level is fully adequate for quantitative decription of the CO2 vibrational dynamics, and all important effects on the vibrational dynamics of CO2 adsorption complexes can be estimated rather accurately (within 5 cm–1) at the DFT level of theory.
Density-dependent population dynamics of mountain pine beetle in thinned and unthinned stands
Authors: MacQuarrie Chris J.K. , Cooke Barry J.
Published: May 2011

Thinning, the selective removal of some trees from a forest, is one way forest managers can reduce the probability that a forest will be susceptible to attack by bark beetles. Although this method has been shown to be effective, it is not clear whether the effect arises when pre-outbreak populations are small or during the epidemic phase when outbreaks are growing. We adopted a population dynamics approach to determine if the effect of limit or basal area thinning could be observed in the form of differential beetle recruitment using lodgepole pine ( Pinus contorta Dougl. ex Loud.) and ponderosa pine ( Pinus ponderosa Dougl. ex P. & C. Laws.) mortality data from previously published studies as a proxy measure of mountain pine beetle ( Dendroctonus ponderosae Hopkins) population size. We found that mountain pine beetle populations exhibit density-dependent population dynamics that are influenced by the silvicultural history of their host’s stand. Thinning did not change the epidemic equilibrium but instead caused a shift in dynamics from linear to nonlinear. In a validation test, the models developed for thinned and unthinned stands predicted reproductive rates in independent locations. These data also suggest the epidemic dynamics of mountain pine beetle may be sensitive to perturbations and to systematic trends associated with climate variability and climate change.
Reproductive success of cavity-nesting birds in partially harvested woodlots
Authors: Straus Melissa A. , Bavrlic Kata , Nol Erica , Burke Dawn M. , Elliott Ken A.
Published: May 2011

Cavity-nesting birds are dependent on large declining and dead trees that are frequently removed during partial harvesting. We compared breeding densities, nest survival, nest site characteristics, food abundance, and reproductive parameters of six species of cavity-nesting birds in partially harvested and reference woodlots in southwestern Ontario, Canada. Silvicultural practices significantly altered woodlot structure, with treatment-specific effects on bark arthropod biomass, fledging dates for the Red-bellied Woodpecker ( Melanerpes carolinus (Linnaeus, 1758)), and site suitability for the Yellow-bellied Sapsucker ( Sphyrapicus varius (Linnaeus, 1766)). Red-bellied Woodpecker, Downy Woodpecker ( Picoides pubescens (Linnaeus, 1766)), and Hairy Woodpecker ( Picoides villosus (Linnaeus, 1766)) experienced lower breeding densities in recently cut sites. Daily survival rates were generally greater for nests positioned higher up in large trees and for Northern Flicker ( Colaptes auratus (Linnaeus, 1758)) nests excavated in healthy and hard wood. Conversely, the Black-capped Chickadee ( Poecile atricapillus (Linnaeus, 1766)) had higher daily survival rates in low, small trees (<10 cm diameter at breast height) and sites with lower arthropod abundance. We conclude that although partial harvesting has the potential to decrease cavity-nesting bird breeding densities, conscientious cavity tree retention during harvest may provide suitable nesting sites that maintain high rates of nest success, regardless of the silvicultural treatments that we examined. However, further research is required to monitor these trends beyond a single harvesting rotation.
Allometry, nitrogen status, and carbon stable isotope composition ofPinus ponderosaseedlings in two growing media with contrasting nursery irrigation regimes
Authors: Dumroese R. Kasten , Page-Dumroese Deborah S. , Brown Robert E.
Published: May 2011

Nursery irrigation regimes that recharged container capacity when target volumetric water content reached 72%, 58%, and 44% (by volume) influenced Pinus ponderosa Douglas ex Lawson & C. Lawson growth more than either a 1:1 (by volume) Sphagnum peat – vermiculite (PV) or a 7:3 (by volume) Sphagnum peat – sawdust (PS) medium. Exponential fertilization avoided confounding irrigation and fertilization. Temporary nitrogen (N) immobilization in PS caused transient allometric differences prior to hardening. Subsequent release of immobilized N during the onset of hardening, when daily N flux decreased from 4.2% to 1.6%, allowed PS seedlings to avoid foliar N dilution experienced by PV seedlings. Media yielded seedlings with similar final morphological characteristics, although PS seedlings had improved N status. At onset, particle density and volumetric water content were similar for both media, but PS held about 10% more water than PV at all water potentials at experiment conclusion. Exposure to the driest water content (44%) decreased seedling growth and root N status compared with cohorts that were provided ample moisture (72%). Despite maximum tissue heterogeneity within samples and regardless of irrigation regime, seedlings became 1.3‰ more depleted of13C as the growing season progressed. Refinement of sampling procedures, with focus on ontogenetics, may improve subsequent use of stable carbon isotopes in nursery research.
Early effects of pre- and post-harvest herbicide application and partial cutting in regenerating aspen – jack pine mixtures in northeastern Ontario
Authors: Man Rongzhou , Rice James A. , MacDonald G. Blake
Published: May 2011

Silvicultural options to obtain mixtures of broadleaved and conifer tree species in boreal forests remain limited, especially for mixtures of broadleaves and shade-intolerant conifers. In this study, we tested a series of treatment packages that included variation in harvesting pattern, site preparation, renewal treatments, and timing and patterns of tending to establish trembling aspen (Populus tremuloides Michx.) and jack pine (Pinus banksiana Lamb.) mixedwoods in intimate mixtures or spatial mosaics in northeastern Ontario. Preharvest spray resulted in fewer but better growth of aspen suckers compared with postharvest spray, which both reduced sucker density and decreased their vigour. Partial cutting reduced aspen regeneration in both the harvested and leave corridors but did not affect other broadleaved species, in this case predominantly red maple (Acer rubrum L.). After treatment, the rapid development of understory vegetation (shrubs, herbs, and grasses) and regeneration reduced total light transmittance at 0.5 m but had no effect at 4.0 m after 5 years. Future stands will be jack pine dominated following both pre- and post-harvest sprays, despite higher density, more uniform distribution, and better growth of broadleaved regeneration with preharvest spray, but will be balanced broadleaf and conifer mixtures in the partial cut areas.
Post-stratified estimation: within-strata and total sample size recommendations
Authors: Westfall James A. , Patterson Paul L. , Coulston John W.
Published: May 2011

Post-stratification is used to reduce the variance of estimates of the mean. Because the stratification is not fixed in advance, within-strata sample sizes can be quite small. The survey statistics literature provides some guidance on minimum within-strata sample sizes; however, the recommendations and justifications are inconsistent and apply broadly for many different population structures. The impacts of minimum within-strata and total sample sizes on estimates of means and standard errors were examined for two forest inventory variables: proportion forestland and cubic net volume. Estimates of the means seem unbiased across a range of minimum within-strata sample sizes. A ratio that described the decrease in variability with increasing sample size allowed for assessment of minimum within-strata sample requirements to obtain stable estimates of means. This metric indicated that the minimum within-strata sample size should be at least 10. Estimates of standard errors were found to be biased at small total sample sizes. To obtain a bias of less than 3%, the required minimum total sample size was 25 for proportion forestland and 75 for cubic net volume. The results presented allow analysts to determine within-stratum and total sample size requirements corresponding to their criteria for acceptable levels of bias and variability.
Acetylsalicylate reduces endothelial and platelet-derived microparticles in patients with coronary artery disease
Authors: Bulut Daniel , Becker Vanessa , Mügge Andreas
Published: May 2011

Previous studies suggest that endothelial progenitor cells (EPCs) contribute to vascular repair processes. In contrast, circulating microparticles (MPs) are reported to be part of a process that is damaging to vascular cells. Numerous studies suggest that the “balance” between EPCs and MPs is important for the integrity of vascular cells and preservation of endothelial function. In the present study, we assess the impact of acetylsalicylate (ASA) — which is, beside statins and physical exercise, a third basic column in the preventive therapy of coronary artery disease (CAD) — on EPCs and MPs in patients with CAD. We investigated the effect of treatment (8 weeks) with ASA (100 mg/d) on endothelial function (flow-mediated vasodilation, FMD), number of circulating EPCs, and endothelial- and platelet-derived microparticles (eMP, pMP) in 15 male patients (age 59.5 ± 12.3 years) with CAD but nonsignificant stenosis. The number of pMPs and eMPs decreased by 62.7% (p < 0.05) and 28.4% (p < 0.05), respectively. The number of circulating EPCs (VEGFR2+CD34+), expressed as ‰ of circulating polymorphonuclear leukocytes, remained unchanged. Despite the reduced number of pMPs and eMPs in response to the ASA therapy, the FMD responses and the maximal dilator effects of nitroglycerin were unaffected. In a control experiment, patients (n = 6) treated with the selective COX-2 inhibitor etoricoxib (90 mg/day) for 8 weeks showed no changes in the number of pMPs, eMPs, and EPCs and in FMD. We report on a novel effect of ASA treatment on the number of circulating endothelial- and platelet-derived microparticles in patients with cardiovascular disease. The mechanism remains elusive, and appears not to be associated with the COX-2 pathway.
Short-term in vivo inhibition of nitric oxide synthase with L-NAME influences the contractile function of single left ventricular myocytes in rats
Authors: Lunz Wellington , Natali Antônio José , Carneiro Miguel Araújo , dos Santos Aggum Capettini Luciano , Baldo Marcelo Perim , de Souza Matheus Ornelas , Quintão Judson Fonseca , Bozi Luiz Henrique Marchesi , Lemos Virginia Soares , Mill José Geraldo
Published: May 2011

The main purpose of this study was to investigate the effects of short-term L-NAME treatment on the contractile function of left ventricle (LV) myocytes and the expression of proteins related to Ca2+ homeostasis. Data from Wistar rats treated with L-NAME (L group, n = 20; 0.7 g/L in drinking water; 7 days) were compared with results from untreated controls (C group, n = 20). Cardiomyocytes from the L group showed increased (p < 0.05) fractional shortening (23%) and maximum rate of shortening (20%) compared with the C group. LV from the L group also showed increased (p < 0.05) expression of the ryanodine receptor 2 and Na+/Ca2+ exchanger proteins (76% and 83%, respectively; p < 0.05). However, the L and C groups showed similar in vivo hemodynamic parameters of cardiac function. In conclusion, short-term NOS inhibition determines an increased expression of Ca2+ regulatory proteins, which contributes to improving cardiomyocyte contractile function, preserving left ventricular function.
The short-term consumption of a moderately high-fat diet alters nitric oxide bioavailability in lean female Zucker rats
Authors: Huang Kan , Huang Yue , Frankel Jessica , Addis Cassandra , Jaswani Lavina , Wehner Paulette S. , Mangiarua Elsa I. , McCumbee William D.
Published: May 2011

To determine whether short-term consumption of a moderately high-fat diet (MHFD) affects nitric oxide (NO) production, the concentration of stable NO metabolites (NOx) in urine and plasma of rats fed a MHFD (15.6 %g fat) or control diet (4.5 %g fat) was measured weekly for 4 weeks. Plasma and urine NOx levels were significantly depressed in the MHFD group by week 1 and remained so for the duration of the study. Decreased NO bioavailability may result from a decrease in NO production or the scavenging of NO by reactive oxygen species (ROS). Because endothelial NOS (eNOS) is the major contributor to NO production and circulating levels of NOx, eNOS expression was measured in several tissues. At week 1, there was a MHFD-associated decrease in eNOS expression in the liver. Subsequently, eNOS expression declined in the heart and kidney medulla of MHFD-fed rats at weeks 3 and 4, respectively. The expression of eNOS in the kidney cortex and adipose tissue did not change. These results suggest that a MHFD alters eNOS expression in a time-dependent and tissue-specific manner. In the liver, NOS activity and tissue levels of NOx and nitrotyrosine were measured. Nitrotyrosine levels were used as an indirect measure of the NO scavenged by ROS. There was a decrease in NOS activity, suggesting that the low levels of hepatic NOx were due, in part, to a decrease in NO production. In addition, there was a dramatic increase in nitrotyrosine formation, suggesting that the decline in hepatic NOx was also due to an increased interaction of NO with ROS. Tyrosine nitration commonly has detrimental effects on proteins. The decrease in NO and increase in protein nitration could potentially have adverse effects on tissue function.
AN URBAN GROWTH MODEL BASED ON A CELLULAR AUTOMATA PHENOMENOLOGICAL FRAMEWORK
Authors: IANNONE G. , TROISI A. , GUARNACCIA C. , D'AGOSTINO P. P. , QUARTIERI J.
Published: May 2011

In this paper we adopt a phenomenological approach in order to develop a suitable Cellular Automata (CA) model capable to satisfactory mimic city growth and urban sprawl. The use of CA in urban expansion modeling is well known since many years, but very rarely it has been related with a down-top approach which considers inhabitants' preferences as a driving tool to characterize the CA algorithm. In addition, we consider as a control mechanism of the cell conversion rate (i.e. the number of cells experiencing conversion into urban use) the logistic function. This function is tuned on the free space (cells) at disposal for the urban development.

In this paper we present the basics of the model and we perform a simple simulation in the case of a generic geographic pattern.
LOCALIZATION OF ACOUSTIC WAVES IN ONE-DIMENSIONAL MODELS WITH CHAOTIC ELASTICITY
Authors: COSTA A. E. B. , DE MOURA F. A. B. F.
Published: May 2011

In this paper we study the propagation of acoustic waves in a one-dimensional system with nonstationary chaotic elasticity distribution. The elasticity distribution is assumed to have a power spectrum S(f) ~ 1/f(2B-3)/(B-1) for B ≥ 1.5. By using a transfer-matrix method we solve the discrete version of the scalar wave equation and compute the Lyapunov exponent. In addition, we apply a second-order finite-difference method for both the time and spatial variables and study the nature of the waves that propagate in the chain. Our numerical data indicate the presence of weak localized acoustic waves for high degree of correlations (B > 2).
ZERO-CHROMATIC FFAG STRAIGHT SECTION
Authors: LAGRANGE J.-B. , PLANCHE T. , MORI Y.
Published: May 2011

Fixed Field Alternating Gradient (FFAG) elements are usually designed in a circular shape, but straight sections can also be imagined. A demonstration using the scaling condition is first shown. Combining different scaling FFAG sections is then discussed and opens new possibilities for scaling FFAGs. As an example, an application with a new lattice proposal for the PRISM project is finally presented in this paper.
KICKER-LESS FFAG: AN APPROACH TO HIGH INTENSITY FFAG
Authors: YOKOI TAKEICHIRO
Published: May 2011

The most challenging issue to realize an accelerator for an Accelerator Driven Sub-critical Reactor system (ADSR) is the handling of high intensity beam—more than 1 mA. For such an application, FFAG is one of most promising candidates. To take advantage of the FFAG as a high intensity accelerator, efficient injection/extraction and acceleration schemes are crucially important. One approach to achieve a high intensity FFAG is to eliminate the kicker magnet from the injection and extraction process and also to implement multi-bunch acceleration.
AN INVESTIGATION INTO MECHANOCHEMICAL SYNTHESIS OF NANOCRYSTALLINE HEXAFERRITE POWDER
Authors: SADEGHI-NIARAKI S. , SEYYED EBRAHIMI S. A. , RAYGAN SH.
Published: May 2011

Nanocrystalline strontium hexaferrite powder has been prepared by a new mechanochemical method in which the single phase hexaferrite was obtained via a sol–gel autocombustion process followed by an intermediate high energy milling step and subsequent annealing. The effects of the intermediate milling on the phase evolution, crystallite size and annealing behavior of the final products were investigated using the X-ray diffraction (XRD) technique. The single phase strontium hexaferrite was obtained at an annealing temperature of 800°C, while this temperature was 1,000°C for the powder synthesized without milling. It could be seen that an intermediate milling accelerates the formation of strontium hexaferrite during the calcination process. The results showed that in the milled powder, the average crystallite size of the ferrite was about 40 nm and much smaller than that of the nonmilled powder. Magnetic properties were also measured by a vibrating sample magnetometer (VSM). The particle morphology was then studied by scanning and transmission electron microscopes (SEM and TEM).
FLEXIBLE FERROMAGNETIC FILAMENTS AS ARTIFICIAL CILIA
Authors: CĒBERS A. , LIVANOVIČS R.
Published: May 2011

The model of an artificial cilia as a flexible ferromagnetic filament in a rotating magnetic field is proposed. Numerical algorithm for the simulation of its behavior is developed and the characteristic shapes of the filament with one fixed end under the action of a rotating field are found. It is concluded that ferromagnetic filaments may be used as mixers in microfluidics.
MAGNETORHEOLOGICAL FLUIDS WITH CARBONYL AND WATER ATOMIZED IRON POWDERS
Authors: BOMBARD ANTONIO J. F. , TEODORO JOÃO VICTOR R.
Published: May 2011

Our aim in this work was to propose the use of a ternary blend of two carbonyl iron powder CIP, mixed with water atomized iron powder (WAIP), to reduce the off-state viscosity, without prejudice of MRF performance in terms of yield stress and torque output. The idea of mix water atomized iron powder with carbonyl iron powder is not new. The US Pat. # 5,900,184 by Weiss et al. (1999) describes that a binary blend, half-to-half, can reduces the viscosity of MRF in the absence of magnetic field, and increase the torque output under field.
FeNbVBALLOY PARTICLES SUSPENDED IN LIQUID GALLIUM: INVESTIGATING THE MAGNETIC PROPERTIES OF THE MR SUSPENSION
Authors: DODBIBA GJERGJ , ONO KENJI , PARK HYUN SEO , MATSUO SEIJI , FUJITA TOYOHISA
Published: May 2011

A MR suspension was prepared by dispersing silica-coated iron alloy particles into a liquid gallium. In other words, the iron alloy particles of 30 to 50 nm in diameter were first prepared and then coated with silica. Next, the particles were then suspended in a liquid Ga (assay: 99.9999%). In addition, the magnetic properties of the synthesized particles and suspension under the influence of the magnetic field were investigated. One of the main findings of this study is that the prepared powder showed a temperature sensitive of magnetization within the testing temperature range of 293–353 K. The saturation magnetization of silica-coated FeNbVB particles was about 0.55 T, whereas the saturation magnetization (297 K) of the synthesized MR suspension was 0.019 T.
UNDERSTANDING ELECTRIC INTERACTIONS IN SUSPENSIONS IN GRADIENT AC ELECTRIC FIELDS I: EXPERIMENTAL
Authors: SHEN YAN , QIU ZHIYONG , TADA SHIGERU
Published: May 2011

When neutrally buoyant poly alpha olefin particles in corn oil were exposed to a gradient ac electric field generated by a spatially periodic electrode array, these particles experienced the negative dielectrophoresis and instability in all the suspensions of concentration range from 0.01% to 5% (v/v). One critical particle concentration was experimentally determined as 1% (v/v) below which the particles in corn oil were segregated to form island-like structures in the lower electric field regions; and above which, particles only formed straight stripes. The island-like structure was suspended in the lowest electric field area. Specially designed experiments with a suspension of 1.126% (v/v) confirmed that there exists particle instability. Anisotropic properties of electric interactions are responsible for particle instability in all the suspensions of different concentrations and island-like structures were formed only in the dilute suspensions in which the particle instability has enough space to be developed.
POLAR-MOLECULE-DOMINATED ELECTRORHEOLOGICAL (PM-ER) FLUIDS: THE PROPERTIES AND EVALUATIONS
Authors: LU KUNQUAN , SHEN RONG , WANG XUEZHAO , WANG DE , SUN GANG
Published: May 2011

In recent years, a new type ER fluids named as polar-molecule-dominated electrorheological (PM-ER) fluids have been developed, of which the yield stress can reach more than 100 kPa and behaves a linear dependence on the electric field. A brief description on the composition and synthesizing method for the materials is given. The main merits of PM-ER fluid are as follows: high yield stress, the shear stress increasing with shear rate up to more than 103 s -1, low current density, rapid electric response and anti-sedimentation. Some perspectives on PM-ER fluid and its applications are presented.
RELATION OF LAMELLAR STRUCTURE AND SHEAR STRESS OF DYNAMIC PM-ER FLUIDS
Authors: LIU D. K. , LI C. , YAO J. , ZHOU L. W. , HUANG J. P.
Published: May 2011

To understand the dynamic rheological behavior of polar molecular electrorheological (PMER) fluids, the shear stress and viscosity of the colloids are compared with the parameters of their lamellar structures which are obtained simultaneously with the rheological characteristics using an electrorheoscope. The results of the experiments and molecular dynamics simulation indicate that the shear stress is mainly contributed by the moving particle rings, and there is an inverse correlation between the width of the moving particle rings and the shear stress.
BEHAVIOR OF MR FLUIDS AT HIGH SHEAR RATE
Authors: HU WEI , WERELEY NORMAN M.
Published: May 2011

The high shear rate behavior of MR fluids is investigated using a concentric rotational cylinder viscometer fabricated in-house. The rotational cylinder viscometer is designed such that a high shear rate of up to 30,000 s-1 can be applied to the MR fluid in a pure shear flow mode. As a comparison, the maximum shear rate of a commercially available parallel disk type rheometer is only up to 1,000 s-1. To determine the shear rate of the MR fluid in the viscometer, an exact expression between torque and angular velocity is established. The yield stress and viscosity of the MR fluid is determined by fitting the expression into the measured torque and angular velocities, and the shear stress as a function of the shear rate is further derived. The magnetic filed strength across the fluid gap is determined based on an electromagnetic field analysis, and the yield stress and viscosity of the fluid as a function of the magnetic filed is established. Specifically, the stability of the MR fluid at high shear rate is also evaluated. Two commercially available MR fluids, i.e., Lord's MRF-132DG and MRF-140CG, are investigated using the rotational cylinder viscometer, and the testing results are compared to the manufacturer's data.
MULTIFRACTAL ANALYSIS OF SCLEROGLUCAN HYDROGELS FOR DRUG DELIVERY
Authors: FRANÇOIS NORA J. , LOSADA M. PIACQUADIO , DARAIO MARTA E.
Published: May 2011

The non-homogeneity and complexity of micro network distribution of hydrogel matrices prepared with two scleroglucan biopolymers obtained with different fermentation times were analyzed using environmental scanning electron microscopy (ESEM) and dynamic rheology.

ESEM images were processed with the tools of multifractal theory using the box-counting method in order to obtain the gels multifractal spectra. Dynamic rheological measurements indicate that both polymeric networks correspond to physical gels that exhibit a solid like behavior. These results suggest the existence of a relationship between the fermentation time used in the polymer production, the degree of self-similarity and the rigidity of the scleroglucan gel structure.
MULTIFRACTAL ANALYSES OF GRAYSCALE AND BINARY SOIL THIN SECTION IMAGES
Authors: ZHOU H. , PERFECT E. , LU Y. Z. , LI B. G. , PENG X. H.
Published: May 2011

Multifractal analyses of binary images of soil thin sections (STS) are widely used to characterize pore structure. However, no geometrical model is known to exist for a binary multifractal. Thus, the multifractality of binary images, and the accuracy of multifractal parameters estimated from them, need to be carefully evaluated. We captured 8-bit depth resolution digital grayscale images of three STS images with dimensions of 1024 × 1024 pixels and a pixel length of 1.9 μm. Random grayscale geometrical multifractal fields (GMF) with similar dimensions and known multifractal parameters were constructed using generators extracted from the STS images. The STS and GMF grayscale images were objectively thresholded to give six binary images. The method of moments was used to compute the log-transformed partition function, log (χ(q, δ)) versus log(δ) where δ is box size, for each grayscale image and its binary counterpart. Consistent linearity was observed in the resulting functions for the grayscale images, indicating, by definition, multifractal behavior. In contrast, the log (χ(q, δ)) versus log(δ) plots for the binary images exhibited a two-region response, with a flat plateau at small scales and linearity at larger scales, indicating they were not true multifractals. Generalized dimensions (Dq) computed from the linear portions of the binary log-transformed partition functions were significantly over estimated for q ≪ 0 and underestimated for q ≫ 0 relative to corresponding Dq values for the grayscale images. Based on these results we contend that binary images are not mathematical multifractals, and that generalized dimensions estimated from them cannot be used to quantify pore space geometry. Instead we encourage further exploration of the use of grayscale images for multifractal characterization of soil structure. This direct approach is theoretically sound and does not require any intermediate thresholding step, which is known to influence the results of multifractal analyses.
KERNEL CONVERGENCE ESTIMATES FOR DIFFUSIONS WITH CONTINUOUS COEFFICIENTS
Authors: ALBANESE CLAUDIO
Published: May 2011

Bidirectional valuation models are based on numerical methods to obtain kernels of parabolic equations. Here we address the problem of robustness of kernel calculations vis a vis floating point errors from a theoretical standpoint. We are interested in kernels of one-dimensional diffusion equations with continuous coefficients as evaluated by means of explicit discretization schemes of uniform step h > 0 in the limit as h → 0. We consider both semidiscrete triangulations with continuous time and explicit Euler schemes with time step so small that the Courant condition is satisfied. We find uniform bounds for the convergence rate as a function of the degree of smoothness. We conjecture these bounds are indeed sharp. The bounds also apply to the time derivatives of the kernel and its first two space derivatives. The proof is constructive and is based on a new technique of path conditioning for Markov chains and a renormalization group argument. We make the simplifying assumption of time-independence and use longitudinal Fourier transforms in the time direction. Convergence rates depend on the degree of smoothness and Hölder differentiability of the coefficients. We find that the fastest convergence rate is of order O(h2) and is achieved if the coefficients have a bounded second derivative. Otherwise, explicit schemes still converge for any degree of Hölder differentiability except that the convergence rate is slower. Hölder continuity itself is not strictly necessary and can be relaxed by an hypothesis of uniform continuity.
STATIONARY WEAK SOLUTIONS FOR STOCHASTIC 3D NAVIER–STOKES EQUATIONS WITH LÉVY NOISE
Authors: DONG ZHAO , LI WENBO V. , ZHAI JIANLIANG
Published: May 2011

We first study the existence of stationary weak solutions of stochastic 3D Navier–Stokes equations involving jumps, and the associated Galerkin stationary probability measures for this case. Then we present a comparison between the Galerkin stationary probability measures for the case driven by Lévy noise and the one driven by Wiener processes.
AVERAGING PRINCIPLE FOR QUASI-LINEAR PARABOLIC PDEs AND RELATED DIFFUSION PROCESSES
Authors: FREIDLIN MARK , KORALOV LEONID
Published: May 2011

Quasi-linear perturbations of a two-dimensional flow with a first integral and the corresponding parabolic PDEs with a small parameter at the second-order derivatives are considered in this paper.
ASYMPTOTIC BEHAVIOR OF TRIMMED SUMS
Authors: BERKES ISTVÁN , HORVÁTH LAJOS , SCHAUER JOHANNES
Published: May 2011

Trimming is a standard method to decrease the effect of large sample elements in statistical procedures, used, e.g., for constructing robust estimators. It is also a powerful tool in understanding deeper properties of partial sums of independent random variables. In this paper we review some basic results of the theory and discuss new results in the central limit theory of trimmed sums. In particular, we show that for random variables in the domain of attraction of a stable law with parameter 0 < α < 2, the asymptotic behavior of modulus trimmed sums depends sensitively on the number of elements eliminated from the sample. We also show that under moderate trimming, the central limit theorem always holds if we allow random centering factors. Finally, we give an application to change point problems.
APPROXIMATION OF INVARIANT FOLIATIONS FOR STOCHASTIC DYNAMICAL SYSTEMS
Authors: SUN XU , KAN XINGYE , DUAN JINQIAO
Published: May 2011

Invariant foliations are geometric structures for describing and understanding the qualitative behaviors of nonlinear dynamical systems. For stochastic dynamical systems, however, these geometric structures themselves are complicated random sets. Thus it is desirable to have some techniques to approximate random invariant foliations. In this paper, invariant foliations are approximated for dynamical systems with small noisy perturbations, via asymptotic analysis. Namely, random invariant foliations are represented as a perturbation of the deterministic invariant foliations, with deviation errors estimated.
ν-MANIFOLDS
Authors: VARSAIE S.
Published: May 2011

ν-manifolds are supermanifolds [Formula: see text] such that [Formula: see text] carries a module structure over the Clifford algebras ℂ[ν] with ν2 = 1. In this paper, ν-manifolds are introduced and the most important examples i.e. ν-projective spaces are studied.
ON THE STABILITY PROBLEM FOR THE $\mathfrak{so}(5)$ FREE RIGID BODY
Authors: CAŞU IOAN
Published: May 2011

In the general case of the [Formula: see text] free rigid body, we will give a list of integrals of motion, which generate the set of Mishchenko's integrals. In the case of [Formula: see text], we prove that there are 15 coordinate-type Cartan subalgebras which on a regular adjoint orbit give 15 Weyl group orbits of equilibria. These coordinate-type Cartan subalgebras are the analogs of the three axes of equilibria for the classical rigid body on [Formula: see text]. The nonlinear stability and instability of these equilibria is analyzed. In addition to these equilibria there are 10 other continuous families of equilibria.
GRAVITY-ASSISTED SOLUTION OF THE MASS GAP PROBLEM FOR PURE YANG–MILLS FIELDS
Authors: KHOLODENKO ARKADY L.
Published: May 2011

In 1979, Louis Witten demonstrated that stationary axially symmetric Einstein field equations and those for static axially symmetric self-dual SU (2) gauge fields can both be reduced to the same (Ernst) equation. In this paper, we use this result as point of departure to prove the existence of the mass gap for quantum source-free Yang–Mills (Y–M) fields. The proof is facilitated by results of our recently published paper, J. Geom. Phys.59 (2009) 600–619. Since both pure gravity, the Einstein–Maxwell and pure Y–M fields are described for axially symmetric configurations by the Ernst equation classically, their quantum descriptions are likely to be interrelated. Correctness of this conjecture is successfully checked by reproducing (by different methods) results of Korotkin and Nicolai, Nucl. Phys. B475 (1996) 397–439, on dimensionally reduced quantum gravity. Consequently, numerous new results supporting the Faddeev–Skyrme (F–S)-type models are obtained. We found that the F–S-like model is best suited for description of electroweak interactions while strong interactions require extension of Witten's results to the SU(3) gauge group. Such an extension is nontrivial. It is linked with the symmetry group SU (3) × SU (2) × U (1) of the standard model. This result is quite rigid and should be taken into account in development of all grand unified theories. Also, the alternative (to the F–S-like) model emerges as by-product of such an extension. Both models are related to each other via known symmetry transformation. Both models possess gap in their excitation spectrum and are capable of producing knotted/linked configurations of gauge/gravity fields. In addition, the paper discusses relevance of the obtained results to heterotic strings and to scattering processes involving topology change. It ends with discussion about usefulness of this information for searches of Higgs boson.