bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Compressor Exit Conditions on Fuel Injector Flows
Authors: Ford C. L. , Carrotte J. F. , Walker A. D.
Published: October 2012

This paper examines the effect of compressor generated inlet conditions on the air flow uniformity through lean burn fuel injectors. Any resulting nonuniformity in the injector flow field can impact on local fuel air ratios and hence emissions performance. The geometry considered is typical of the lean burn systems currently being proposed for future, low emission aero engines. Initially, Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) predictions were used to examine the flow field development between compressor exit and the inlet to the fuel injector. This enabled the main flow field features in this region to be characterized along with identification of the various stream-tubes captured by the fuel injector passages. The predictions indicate the resulting flow fields entering the injector passages are not uniform. This is particularly evident in the annular passages furthest away from the injector centerline which pass the majority of the flow which subsequently forms the main reaction zone within the flame tube. Detailed experimental measurements were also undertaken on a fully annular facility incorporating an axial compressor and lean burn combustion system. The measurements were obtained at near atmospheric pressure/temperatures and under nonreacting conditions. Time-resolved and time-averaged data were obtained at various locations and included measurements of the flow field issuing from the various fuel injector passages. In this way any nonuniformity in these flow fields could be quantified. In conjunction with the numerical data, the sources of nonuniformities in the injector exit plane were identified. For example, a large scale bulk variation (+/−10%) of the injector flow field was attributed to the development of the flow field upstream of the injector, compared with localized variations (+/−5%) that were generated by the injector swirl vane wakes. Using this data the potential effects on fuel injector emissions performance can be assessed.
Molecular Dynamics Simulation on Effect of Nanoparticle Aggregation on Transport Properties of a Nanofluid1
Authors: Kang Hongbo , Zhang Yuwen , Yang Mo , Li Ling
Published: October 2012

Effect of nanoparticle aggregation on the transport properties that include thermal conductivity and viscosity of nanofluids is studied by molecular dynamics (MD) simulation. Unlike many other MD simulations on nanofluids which have only one nanoparticle in the simulation box with periodic boundary condition, in this work, multiple nanoparticles are placed in the simulation box which makes it possible to simulate the aggregation of the nanoparticles. Thermal conductivity and viscosity of the nanofluid are calculated using Green–Kubo method and results show that the nanoparticle aggregation induces a significant enhancement of thermal conductivity in nanofluid, while the increase of viscosity is moderate. The results also indicate that different configurations of the nanoparticle cluster result in different enhancements of thermal conductivity and increase of viscosity in the nanofluid.
Considerations on the Numerical Modeling and Performance of Axial Swirlers Under Relight Conditions
Authors: Grech Nicholas , Koupper Charlie , Zachos Pavlos K. , Pachidis Vassilios , Singh Riti
Published: October 2012

Numerical modeling of aero engine combustors under relight conditions is a matter of continuously increasing importance due to the demanding engine certification regulations. In order to reduce the complexity and the cost of the numerical modeling, common practice is to replace the atomizer’s swirlers with velocity profiles boundary conditions, very often scaled down from nominal operating conditions assuming similarity of the swirler flowfield. The current numerical study focuses on the flowfield characteristics of an axially swirled atomizer operating within a windmilling engine environment. The scalability of the velocity profile from higher power settings is examined. Observations on the performance of the axial swirler under relight conditions are also made. Experimental data was used as a validation platform for the numerical solver, after a grid sensitivity study and a turbulence model selection process. Boundary conditions for simulating the windmilling environment were extracted from experimental work. The swirler axial and tangential velocity profiles were normalized using the swirler inlet velocity. Results showed that both profiles are only scalable for windmilling conditions of high flight Mach number (≥ 0.5). At low flight Mach numbers, the actual profile had a lower velocity than that predicted through scaling. The swirl number was found to deteriorate significantly with the flight velocity following a linear trend, reducing significantly the expected flame quality. As a consequence the burner is forced to operate at the edge of its stability loop with low certainty regarding its successful relight.
Quantifying Cyclic Variability in a Multicylinder HCCI Engine With High Residuals
Authors: Hellström Erik , Larimore Jacob , Stefanopoulou Anna , Sterniak Jeff , Jiang Li
Published: October 2012

Cyclic variability (CV) in lean homogeneous charge compression ignition (HCCI) combustion at the limits of operation is a known phenomenon, and this work aims at investigating the dominant effects for the cycle evolution at these conditions in a multicylinder engine. Experiments are performed in a four-cylinder engine at the operating limits at late phasing of lean HCCI operation with negative valve overlap (nvo). A combustion analysis method that estimates the unburned fuel mass on a per-cycle basis is applied on both main combustion and the nvo period revealing and quantifying the dominant effects for the cycle evolution at high CV. The interpretation of the results and comparisons with data from a single-cylinder engine indicate that, at high CV, the evolution of combustion phasing is dominated by low-order deterministic couplings similar to the single-cylinder behavior. Variations, such as air flow and wall temperature, between cylinders strongly influence the level of CV but the evolution of the combustion phasing is governed by the interactions between engine cycles of the individual cylinders.
Tribological Behaviors of Titanium Nitride- and Chromium-Nitride-Based Physical Vapor Deposition Coating Systems
Authors: Cai Feng , Huang Xiao , Yang Qi , Nagy Doug
Published: October 2012

This study investigates the effects of the deposition process and coating composition on microstructural and tribological properties of TiN- and CrN-based coating systems. Coatings were produced using various PVD-based processes—electron beam (EB), cathodic arc (CA), and plasma enhanced magnetron sputtering (PEMS). All coated samples were evaluated for their composition, microstructure, and surface morphology. Coating mechanical properties such as hardness, Young’s modulus, and coefficient of friction were also studied and related to their microstructures, wear, and erosion resistances. It was found that hardness (H), Young’s modulus (E), and coefficient of friction had impact on both wear and erosion rates. In particular, the H3/E2 ratio was inversely proportional to the specific wear rate. For erosion behavior, higher H3/E2 ratios relate to lower erosion rates at low impingement angles, whereas higher H3/E2 ratios relate to higher erosion rates at high impingement angles.
Assessing Alternative Fuels for Helicopter Operation
Authors: Alexiou A. , Tsalavoutas A. , Pons B. , Aretakis N. , Roumeliotis I. , Mathioudakis K.
Published: October 2012

At present, nearly 100% of aviation fuel is derived from petroleum using conventional and well known refining technology. However, the fluctuations of the fuel price and the vulnerability of crude oil sources have increased the interest of the aviation industry in alternate energy sources. The motivation of this interest is actually twofold: firstly, alternative fuels will help to stabilize price fluctuations by relieving the worldwide demand for conventional fuel. Secondly, alternative fuels could provide environmental benefits including a substantial reduction of emitted CO2 over the fuel life cycle. Thus, the ideal alternative fuel will fulfill both requirements: relieve the demand for fuels derived from crude oil and significantly reduce CO2 emissions. In the present paper, the effects of various alternative fuels on the operation of a medium transport/utility helicopter are investigated using performance models of the helicopter and its associated turboshaft engine. These models are developed in an object-oriented simulation environment that allows a direct mechanical connection to be established between them in order to create an integrated model. Considering the case of a typical mission for the specific helicopter/engine combination, a comparative evaluation of conventional and alternative fuels is then carried out and performance results are presented at both engine and helicopter levels.
Buckling Instability of Carbon Nanotube Atomic Force Microscope Probe Clamped in an Elastic Medium
Authors: Shi Jin-Xing , Natsuki Toshiaki , Lei Xiao-Wen , Ni Qing-Qing
Published: October 2012

Carbon nanotubes (CNTs) can be used as atomic force microscope (AFM) probes due to their robust mechanical properties, high aspect ratio and small diameter. In this study, a model of CNTs clamped in an elastic medium is proposed as CNT AFM probes. The buckling instability of the CNT probe clamped in elastic medium is analyzed based on the nonlocal Euler–Bernoulli beam model and the Whitney–Riley model. The clamped length of CNTs, and the stiffness of elastic medium affect largely on the stability of CNT AFM probe, especially at high buckling mode. The result shows that the buckling stability of the CNT AFM probe can be largely enhanced by increasing the stiffness of elastic medium. Moreover, the nonlocal effects of buckling instability are investigated and found to be lager for high buckling mode. The theoretical investigation on the buckling stability would give a useful reference for designing CNT as AFM probes.
Propagating Skewness and Kurtosis Through Engineering Models for Low-Cost, Meaningful, Nondeterministic Design
Authors: Anderson Travis V. , Mattson Christopher A.
Published: October 2012

System models help designers predict actual system output. Generally, variation in system inputs creates variation in system outputs. Designers often propagate variance through a system model by taking a derivative-based weighted sum of each input’s variance. This method is based on a Taylor-series expansion. Having an output mean and variance, designers typically assume the outputs are Gaussian. This paper demonstrates that outputs are rarely Gaussian for nonlinear functions, even with Gaussian inputs. This paper also presents a solution for system designers to more meaningfully describe the system output distribution. This solution consists of using equations derived from a second-order Taylor series that propagate skewness and kurtosis through a system model. If a second-order Taylor series is used to propagate variance, these higher-order statistics can also be propagated with minimal additional computational cost. These higher-order statistics allow the system designer to more accurately describe the distribution of possible outputs. The benefits of including higher-order statistics in error propagation are clearly illustrated in the example of a flat-rolling metalworking process used to manufacture metal plates.
Sequential Quadratic Programming for Robust Optimization With Interval Uncertainty
Authors: Zhou Jianhua , Cheng Shuo , Li Mian
Published: October 2012

Uncertainty plays a critical role in engineering design as even a small amount of uncertainty could make an optimal design solution infeasible. The goal of robust optimization is to find a solution that is both optimal and insensitive to uncertainty that may exist in parameters and design variables. In this paper, a novel approach, sequential quadratic programming for robust optimization (SQP-RO), is proposed to solve single-objective continuous nonlinear optimization problems with interval uncertainty in parameters and design variables. This new SQP-RO is developed based on a classic SQP procedure with additional calculations for constraints on objective robustness, feasibility robustness, or both. The obtained solution is locally optimal and robust. Eight numerical and engineering examples with different levels of complexity are utilized to demonstrate the applicability and efficiency of the proposed SQP-RO with the comparison to its deterministic SQP counterpart and RO approaches using genetic algorithms. The objective and/or feasibility robustness are verified via Monte Carlo simulations.
Optimization Based Algorithms for Uncertainty Propagation Through Functions With Multidimensional Output Within Evidence Theory
Authors: Gogu Christian , Qiu Youchun , Segonds Stéphane , Bes Christian
Published: October 2012

Evidence theory is one of the approaches designed specifically for dealing with epistemic uncertainty. This type of uncertainty modeling is often useful at preliminary design stages where the uncertainty related to lack of knowledge is the highest. While multiple approaches for propagating epistemic uncertainty through one-dimensional functions have been proposed, propagation through functions having a multidimensional output that need to be considered at once received less attention. Such propagation is particularly important when the multiple function outputs are not independent, which frequently occurs in real world problems. The present paper proposes an approach for calculating belief and plausibility measures by uncertainty propagation through functions with multidimensional, nonindependent output by formulating the problem as one-dimensional optimization problems in spite of the multidimensionality of the output. A general formulation is first presented followed by two special cases where the multidimensional function is convex and where it is linear over each focal element. An analytical example first illustrates the importance of considering all the function outputs at once when these are not independent. Then, an application example to preliminary design of a propeller aircraft then illustrates the proposed algorithm for a convex function. An approximate solution found to be almost identical to the exact solution is also obtained for this problem by linearizing the previous convex function over each focal element.
Computational Investigation of Fibrin Mechanical and Damage Properties at the Interface Between Native Cartilage and Implant
Authors: Vahdati Ali , Zhao Yang , Ovaert Timothy C. , Wagner Diane R.
Published: October 2012

Scaffold-based tissue-engineered constructs as well as cell-free implants offer promising solutions to focal cartilage lesions. However, adequate mechanical stability of these implants in the lesion is required for successful repair. Fibrin is the most common clinically available adhesive for cartilage implant fixation, but fixation quality using fibrin is not well understood. The objectives of this study were to investigate the conditions leading to damage in the fibrin adhesive and to determine which adhesive properties are important in preventing delamination at the interface. An idealized finite element model of the medial compartment of the knee was created, including a circular defect and an osteochondral implant. Damage and failure of fibrin at the interface was represented by a cohesive zone model with coefficients determined from an inverse finite element method and previously published experimental data. Our results demonstrated that fibrin glue alone may not be strong enough to withstand physiologic loads in vivo while fibrin glue combined with chondrocytes more effectively prevents damage at the interface. The results of this study suggest that fibrin fails mainly in shear during off-axis loading and that adhesive materials that are stronger or more compliant than fibrin may be good alternatives due to decreased failure at the interface. The present model may be used to improve design and testing protocols of bioadhesives and give insight into the failure mechanisms of cartilage implant fixation in the knee joint.
Reaction mechanisms of oxygen plasma interaction with organosilicate low-k materials containing organic crosslinking groups
Authors: Chaudhari Mrunalkumar , Du Jincheng
Published: October 2012

Integration of low dielectric constant (k) materials such as organosilicate glasses (OSG) into microelectronic processing demands a better of understanding the plasma/OSG interactions during plasma etching and ashing of these materials, based on which low-k materials with higher radiation resistance and better mechanical behaviors can be developed and optimized plasma processing conditions can be introduced to ensure continued miniaturization of semiconductor devices. Introducing organic crosslinking (e.g., –CH2–) in OSG has been shown to be an effective measure to improve the mechanical properties but their effect on plasma interaction is still not fully understood. In this paper, ab initio based molecular dynamics simulations have been employed to investigate the effect of the oxygen plasma on the carbon-bridged silicate networks in the OSG material. The results show that organic crosslinking in the Si–O–Si network leads to lower energy reaction pathways with atomic oxygen radicals that result in breakage of Si–CH2–Si linkages instead of Si–CH3 bonds and, consequently, a decrease in carbon removal. The incorporation of organic crosslinking groups can thus improve the resistance to oxygen plasma damage of OSG and, together with better mechanical properties, can lead to the design of stronger low-k dielectric films.
Cupping artifact correction and automated classification for high‐resolution dedicated breast CT images
Authors: Yang Xiaofeng , Wu Shengyong , Sechopoulos Ioannis , Fei Baowei
Published: October 2012

Purpose:

To develop and test an automated algorithm to classify the different tissues present in dedicated breast CT images.

Methods:

The original CT images are first corrected to overcome cupping artifacts, and then a multiscale bilateral filter is used to reduce noise while keeping edge information on the images. As skin and glandular tissues have similar CT values on breast CT images, morphologic processing is used to identify the skin mask based on its position information. A modified fuzzy C‐means (FCM) classification method is then used to classify breast tissue as fat and glandular tissue. By combining the results of the skin mask with the FCM, the breast tissue is classified as skin, fat, and glandular tissue. To evaluate the authors’ classification method, the authors use Dice overlap ratios to compare the results of the automated classification to those obtained by manual segmentation on eight patient images.

Results:

The correction method was able to correct the cupping artifacts and improve the quality of the breast CT images. For glandular tissue, the overlap ratios between the authors’ automatic classification and manual segmentation were 91.6% ± 2.0%.

Conclusions:

A cupping artifact correction method and an automatic classification method were applied and evaluated for high‐resolution dedicated breast CT images. Breast tissue classification can provide quantitative measurements regarding breast composition, density, and tissue distribution.
Incidence of Staphylococcus aureus and Analysis of Associated Bacterial Communities on Food Industry Surfaces
Authors: Gutiérrez Diana , Delgado Susana , Vázquez-Sánchez Daniel , Martínez Beatriz , Cabo Marta López , Rodríguez Ana , Herrera Juan J. , García Pilar
Published: October 2012

Biofilms are a common cause of food contamination with undesirable bacteria, such as pathogenic bacteria.
Staphylococcus aureus
is one of the major bacteria causing food-borne diseases in humans. A study designed to determine the presence of
S. aureus
on food contact surfaces in dairy, meat, and seafood environments and to identify coexisting microbiota has therefore been carried out. A total of 442 samples were collected, and the presence of
S. aureus
was confirmed in 6.1% of samples. Sixty-three
S. aureus
isolates were recovered and typed by random amplification of polymorphic DNA (RAPD). Profiles were clustered into four groups which were related to specific food environments. All isolates harbored some potential virulence factors such as enterotoxin production genes, biofilm formation-associated genes, antibiotic resistance, or lysogeny. PCR-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprints of bacterial communities coexisting with
S. aureus
revealed the presence of bacteria either involved in food spoilage or of concern for food safety in all food environments. Food industry surfaces could thus be a reservoir for
S. aureus
forming complex communities with undesirable bacteria in multispecies biofilms. Uneven microbiological conditions were found in each food sector, which indicates the need to improve hygienic conditions in food processing facilities, particularly the removal of bacterial biofilms, to enhance the safety of food products.
A New Bacterial Disease on Mandevilla sanderi, Caused by Pseudomonas savastanoi: Lessons Learned for Bacterial Diversity Studies
Authors: Eltlbany Namis , Prokscha Zsa-Zsa , Castañeda-Ojeda M. Pilar , Krögerrecklenfort Ellen , Heuer Holger , Wohanka Walter , Ramos Cayo , Smalla Kornelia
Published: October 2012

Leaf lesions of
Mandevilla sanderi
were shown to be caused by
Pseudomonas savastanoi
. While BOX fingerprints were similar for
P. savastanoi
isolates from different host plants, plasmid restriction patterns and sequencing of plasmid-located pathogenicity determinants revealed that
Mandevilla
isolates contained similar plasmids distinct from those of other isolates. A
repA
-based detection method was established.
Ethylene Glycol Metabolism by Pseudomonas putida
Authors: Mückschel Björn , Simon Oliver , Klebensberger Janosch , Graf Nadja , Rosche Bettina , Altenbuchner Josef , Pfannstiel Jens , Huber Armin , Hauer Bernhard
Published: October 2012

In this study, we investigated the metabolism of ethylene glycol in the
Pseudomonas putida
strains KT2440 and JM37 by employing growth and bioconversion experiments, directed mutagenesis, and proteome analysis. We found that strain JM37 grew rapidly with ethylene glycol as a sole source of carbon and energy, while strain KT2440 did not grow within 2 days of incubation under the same conditions. However, bioconversion experiments revealed metabolism of ethylene glycol by both strains, with the temporal accumulation of glycolic acid and glyoxylic acid for strain KT2440. This accumulation was further increased by targeted mutagenesis. The key enzymes and specific differences between the two strains were identified by comparative proteomics. In
P. putida
JM37, tartronate semialdehyde synthase (Gcl), malate synthase (GlcB), and isocitrate lyase (AceA) were found to be induced in the presence of ethylene glycol or glyoxylic acid. Under the same conditions, strain KT2440 showed induction of AceA only. Despite this difference, the two strains were found to use similar periplasmic dehydrogenases for the initial oxidation step of ethylene glycol, namely, the two redundant pyrroloquinoline quinone (PQQ)-dependent enzymes PedE and PedH. From these results we constructed a new pathway for the metabolism of ethylene glycol in
P. putida
. Furthermore, we conclude that
Pseudomonas putida
might serve as a useful platform from which to establish a whole-cell biocatalyst for the production of glyoxylic acid from ethylene glycol.
A Novel
meso
-Diaminopimelate Dehydrogenase from Symbiobacterium thermophilum: Overexpression, Characterization, and Potential for
d
-Amino Acid Synthesis
Authors: Gao Xiuzhen , Chen Xi , Liu Weidong , Feng Jinhui , Wu Qiaqing , Hua Ling , Zhu Dunming
Published: October 2012

meso
-Diaminopimelate dehydrogenase (
meso
-DAPDH) is an NADP
+
-dependent enzyme which catalyzes the reversible oxidative deamination on the
d
-configuration of
meso
-2,6-diaminopimelate to produce
l
-2-amino-6-oxopimelate. In this study, the gene encoding a
meso
-diaminopimelate dehydrogenase from
Symbiobacterium thermophilum
was cloned and expressed in
Escherichia coli
. In addition to the native substrate
meso
-2,6-diaminopimelate, the purified enzyme also showed activity toward
d
-alanine,
d
-valine, and
d
-lysine. This enzyme catalyzed the reductive amination of 2-keto acids such as pyruvic acid to generate
d
-amino acids in up to 99% conversion and 99% enantiomeric excess. Since
meso
-diaminopimelate dehydrogenases are known to be specific to
meso
-2,6-diaminopimelate, this is a unique wild-type
meso
-diaminopimelate dehydrogenase with a more relaxed substrate specificity and potential for
d
-amino acid synthesis. The enzyme is the most stable
meso
-diaminopimelate dehydrogenase reported to now. Two amino acid residues (F146 and M152) in the substrate binding sites of
S. thermophilum meso
-DAPDH different from the sequences of other known
meso
-DAPDHs were replaced with the conserved amino acids in other
meso
-DAPDHs, and assay of wild-type and mutant enzyme activities revealed that F146 and M152 are not critical in determining the enzyme's substrate specificity. The high thermostability and relaxed substrate profile of
S. thermophilum meso
-DAPDH warrant it as an excellent starting enzyme for creating effective
d
-amino acid dehydrogenases by protein engineering.
Probing the Role of Sigma π Interaction and Energetics in the Catalytic Efficiency of Endo-1,4-β-Xylanase
Authors: Singh Raushan Kumar , Tiwari Manish Kumar , Kim In-Won , Chen Zhilei , Lee Jung-Kul
Published: October 2012

Chaetomium globosum
endo-1,4-β-xylanase (XylCg) is distinguished from other xylanases by its high turnover rate (1,860 s
−1
), the highest ever reported for fungal xylanases. One conserved amino acid, W48, in the substrate binding pocket of wild-type XylCg was identified as an important residue affecting XylCg's catalytic efficiency.
Novel Bacterial Community Associated with 500-Year-Old Unpreserved Archaeological Wood from King Henry VIII's Tudor Warship the Mary Rose
Authors: Preston Joanne , Watts Joy E. M. , Jones Mark
Published: October 2012

A 500-year-old unpreserved
Mary Rose
sample, historically containing an iron bolt, was analyzed using enrichment cultures and 16S sequencing. The novel community of bacteria present demonstrates a biological pathway of Fe and S oxidation and a range of acid-generating metabolisms, with implications for preservation and biogeochemical cycling.
Lactate and Acrylate Metabolism by Megasphaera elsdenii under Batch and Steady-State Conditions
Authors: Prabhu Rupal , Altman Elliot , Eiteman Mark A.
Published: October 2012

The growth of
Megasphaera elsdenii
on lactate with acrylate and acrylate analogues was studied under batch and steady-state conditions. Under batch conditions, lactate was converted to acetate and propionate, and acrylate was converted into propionate. Acrylate analogues 2-methyl propenoate and 3-butenoate containing a terminal double bond were similarly converted into their respective saturated acids (isobutyrate and butyrate), while crotonate and lactate analogues 3-hydroxybutyrate and (
R
)-2-hydroxybutyrate were not metabolized. Under carbon-limited steady-state conditions, lactate was converted to acetate and butyrate with no propionate formed. As the acrylate concentration in the feed was increased, butyrate and hydrogen formation decreased and propionate was increasingly generated, while the calculated ATP yield was unchanged.
M. elsdenii
metabolism differs substantially under batch and steady-state conditions. The results support the conclusion that propionate is not formed during lactate-limited steady-state growth because of the absence of this substrate to drive the formation of lactyl coenzyme A (CoA) via propionyl-CoA transferase. Acrylate and acrylate analogues are reduced under both batch and steady-state growth conditions after first being converted to thioesters via propionyl-CoA transferase. Our findings demonstrate the central role that CoA transferase activity plays in the utilization of acids by
M. elsdenii
and allows us to propose a modified acrylate pathway for
M. elsdenii
.
Genome Sequence of Pichia kudriavzevii M12, a Potential Producer of Bioethanol and Phytase
Authors: Chan Giek Far , Gan Han Ming , Ling How Lie , Rashid Noor Aini Abdul
Published: October 2012

A draft genome sequence of
Pichia kudriavzevii
M12 is presented here. The genome reveals the presence of genes encoding enzymes involved in xylose utilization and the pentose phosphate pathway for bioethanol production. Strain M12 is also a potential producer of phytases, enzymes useful in food processing and agriculture.
Monitoring fitness levels and detecting implications for health in a French population: an observational study
Authors: Nassif Hala , Sedeaud Adrien , Abidh Elisa , Schipman Julien , Tafflet Muriel , Deschamps Thibault , Maillet Hervé , Ovigneur Hervé , Desgorces François-Denis , Toussaint Jean-François
Published: October 2012

Objective

To analyse the physical fitness of a large sample of the French population across different ages.

Design

Observational cross-sectional study.

Setting

Data were collected from the Athletic Track and Field Federation, which organised events dedicated to measuring physical fitness. The events took place in 22 regions between 2006 and 2010.

Participants

French volunteer citizens (N=31 349) aged between 4 and 80 years old who participated in events dedicated to measuring physical fitness.

Primary and secondary outcome measures

We assessed the results of the following fitness tests: 20 m shuttle run, standing broad jump, repeated squat jump, 4×10 m shuttle run, speed, flexibility and push-ups in relation to age and body mass index (BMI) using Spearman's rho, a one-way analysis of variance. A bi-exponential model was used to represent the performance with age.

Results

Our major results showed higher performances for men and for subjects with normal BMI at all age groups except for the flexibility test. BMI was strongly correlated across all ages with physical fitness p<0.0001. Furthermore, through bi-exponential model, a mean peak performance was identified at 26.32 years of age for men and 22.18 years of age for women.

Conclusions

Physical fitness assessment using a simple series of tests on the general population offers an important indicator of health status. The possibility of observing the evolution of fitness levels with time provides an important monitoring method from a public health perspective. Further research is needed to reinforce and evaluate the approach.
The effect of healthcare delivery privatisation on avoidable mortality: longitudinal cross-regional results from Italy, 1993–2003
Authors: Quercioli Cecilia , Messina Gabriele , Basu Sanjay , McKee Martin , Nante Nicola , Stuckler David
Published: October 2012

Background

During the 1990s, Italy privatised a significant portion of its healthcare delivery. The authors compared the effectiveness of private and public sector healthcare delivery in reducing avoidable mortality (deaths that should not occur in the presence of effective medical care).

Methods

The authors calculated the average rate of change in age-standardised avoidable mortality rates in 19 of Italy's regions from 1993 to 2003. Multivariate regression models were used to analyse the relationship between rates of change in avoidable mortality and levels of spending on public versus private healthcare delivery, controlling for potential demographic and economic confounders.

Results

Greater spending on public delivery of health services corresponded to faster reductions in avoidable mortality rates. Each €100 additional public spending per capita on NHS delivery was independently associated with a 1.47% reduction in the rate of avoidable mortality (p=0.003). In contrast, spending on private sector services had no statistically significant effect on avoidable mortality rates (p=0.557). A higher percentage of spending on private sector delivery was associated with higher rates of avoidable mortality (p=0.002). The authors found that neither public nor private sector delivery spending was significantly associated with non-avoidable mortality rates, plausibly because non-avoidable mortality is insensitive to healthcare services.

Conclusion

Public spending was significantly associated with reductions in avoidable mortality rates over time, while greater private sector spending was not at the regional level in Italy.
VIOLATION OF CHANDRASEKHAR MASS LIMIT: THE EXCITING POTENTIAL OF STRONGLY MAGNETIZED WHITE DWARFS
Authors: DAS UPASANA , MUKHOPADHYAY BANIBRATA
Published: October 2012

We consider a relativistic, degenerate, electron gas under the influence of a strong magnetic field, which describes magnetized white dwarfs. Landau quantization changes the density of states available to the electrons, thus modifying the underlying equation of state. In the presence of very strong magnetic fields a maximum of either one, two or three Landau level(s) is/are occupied. We obtain the mass–radius relations for such white dwarfs and their detailed investigation leads us to propose the existence of white dwarfs having a mass ~2.3M⊙, which overwhelmingly exceeds the Chandrasekhar mass limit.
STUDY OF THE NEAR INFRARED-MEDIATED HEATING OF DISPERSIONS OF PROTEIN-COATED PRISTINE AND CARBOXYLATED SINGLE-WALLED CARBON NANOTUBES
Authors: SHEARDY ALEX T. , TAYLOR JEREMY J. , CHILEK JENNIFER L. , LI SYNYOUNG , WANG RUHUNG , DRAPER ROCKFORD K. , PANTANO PAUL
Published: October 2012

Previously, we demonstrated the selective NIR-mediated ablation of tumor cells in vitro using pristine single-walled carbon nanotubes (SWNTs) with adsorbed tumor-targeting ligands and carboxylated SWNTs with covalently-attached ligands. The covalent approach is advantageous in ensuring that protein ligands remain associated with the NIR-absorbing SWNTs in biological matrices and the noncovalent approach has the advantage of enabling SWNT functionalization without perturbation of the SWNT lattice and photothermal properties. Herein, we compare the ability of moderately-carboxylated (~ 4 at.% carboxylic acid groups) and pristine SWNT materials to absorb 808 nm radiation and convert it to heat. Under conditions of a constant 808 nm laser power density, the approach involved measuring the temperature of aqueous dispersions of protein-coated SWNTs as a function of the irradiation time. Nearly identical temperature profiles were observed for dispersions of moderately-carboxylated and pristine SWNTs possessing matched 808 nm optical densities and equivalent concentrations of carbonaceous species (i.e., SWNTs and amorphous carbon impurities). The results indicate that the amount of carbonaceous species in purified dispersions of protein-coated SWNTs is more important for converting absorbed 808 nm radiation into heat than whether or not the SWNTs were moderately carboxylated, and that moderately-carboxylated SWNTs could be the SWNT-material of choice for the targeted photothermal ablation of tumor cells.
HIGH-ORDER EXPLICIT TIME-INTEGRATORS FOR DISCONTINUOUS GALERKIN DISCRETIZATIONS OF THE MAXWELL EQUATIONS
Authors: FAHS H. , SAFA M.
Published: October 2012

We investigate the practical implementation of a high-order explicit time-stepping method based on polynomial approximations, for possible application to large-scale problems in electromagnetics. After the spatial discretization by a high-order discontinuous Galerkin method, we obtain a linear system of differential equations of the form, [Formula: see text], where [Formula: see text] is a matrix containing the spatial derivatives and t is the time variable. The formal solution can be written in terms of the matrix exponential, [Formula: see text], acting on some vectors. We introduce a general family of time-integrators based on the approximation of [Formula: see text] by Jacobi polynomial expansions. We discuss the efficient implementation of this technique, and based on some test problems, we compare the virtues and shortcomings of the algorithm. We also demonstrate how these schemes provide an efficient alternative to standard explicit integrators for computing solutions over long time intervals.
Sonic hedgehog promotes autophagy of vascular smooth muscle cells
Authors: Li Haijie , Li Jingjing , Li Yuenan , Singh Pavneet , Cao Liang , Xu Li-juan , Li Dong , Wang Yuebing , Xie Zhiping , Gui Yu , Zheng Xi-Long
Published: October 2012

Sonic hedgehog (Shh) is a morphogen critically involved in development that is reexpressed in atherosclerotic lesions. It also stimulates proliferation of vascular smooth muscle cells (SMCs). Autophagy in vascular SMCs is known to promote SMC survival and increase plaque stability. The aim of this study was to investigate whether Shh induces autophagy of vascular SMCs. Our study showed that both Shh protein and microtubule-associated protein 1 light chain 3 (LC3)-II were increased in SMCs within neointimal lesions of mouse common carotid arteries. In cultured mouse aortic SMCs, recombinant mouse Shh stimulated LC3-II levels. Overexpression of wild-type mouse Shh through the tetracycline-regulated expression-inducible system in human aortic SMCs time-dependently increased the levels of LC3-II and also stimulated protein kinase B (AKT) phosphorylation. Pretreatment with AKT inhibitor IV (AKTI IV) inhibited AKT phosphorylation and the increase in LC3-II. Shh-induced autophagy was further confirmed by the formation of autophagosomes as detected by immunostaining and transmission electron microscopy, which was inhibited by AKTI IV. Shh further increased SMC LC3-II in the presence of bafilomycin A1, (2 S,3 S)- trans-epoxysuccinyl-l-leucylamido-3-methylbutane ethyl ester, and pepstatin A or siRNA for the autophagy-related gene 7 (ATG7). In addition, Shh induced SMC proliferation, which was inhibited not only by AKTI IV but also by cyclopamine, an inhibitor of Shh receptor. Inhibition of autophagy with 3-methyladenine (3-MA), bafilomycin A1, or ATG7 siRNA resulted in inhibition of cell proliferation. Treatment with 3-MA, AKTI IV, or cyclopamine inhibited neointima formation in mouse common carotid arteries. Taken together, our results have shown that Shh induces autophagy of vascular SMCs involving AKT activation, suggesting a role of autophagy in Shh-induced cellular responses.
Antioxidant mimetics modulate oxidative stress and cellular signaling in airway epithelial cells infected with respiratory syncytial virus
Authors: Hosakote Yashoda M. , Komaravelli Narayana , Mautemps Nicolas , Liu Tianshuang , Garofalo Roberto P. , Casola Antonella
Published: October 2012

Respiratory syncytial virus (RSV) is one of the most common causes of bronchiolitis and pneumonia among infants and young children worldwide. In previous investigations, we have shown that RSV infection induces rapid generation of reactive oxygen species (ROS), which modulate viral-induced cellular signaling, and downregulation of antioxidant enzyme (AOE) expression, resulting in oxidative stress in vitro and in vivo, which plays a pathogenetic role in RSV-induced lung disease. In this study, we determined whether pharmacological intervention with synthetic catalytic scavengers could reduce RSV-induced proinflammatory gene expression and oxidative cell damage in an in vitro model of infection. Treatment of airway epithelial cells (AECs) with the salen-manganese complexes EUK-8 or EUK-189, which possess superoxide dismutase, catalase, and glutathione peroxidase activity, strongly reduced RSV-induced ROS formation by increasing cellular AOE enzymatic activity and levels of the lipid peroxidation products F2-8-isoprostane and malondialdehyde, which are markers of oxidative stress. Treatment of AECs with AOE mimetics also significantly inhibited RSV-induced cytokine and chemokine secretion and activation of the transcription factors nuclear factor-κB and interferon regulatory factor-3, which orchestrate proinflammatory gene expression. Both EUKs were able to reduce viral replication, when used at high doses. These results suggest that increasing antioxidant cellular capacities can significantly impact RSV-associated oxidative cell damage and cellular signaling and could represent a novel therapeutic approach in modulating virus-induced lung disease.
The physiological legacy of the Fenn, Rahn, and Otis school
Authors: West John B.
Published: October 2012

Extraordinary advances in respiratory physiology occurred between 1941 and 1956 in the Department of Physiology, University of Rochester. These were principally the result of a collaboration between Wallace Fenn, Hermann Rahn, and Arthur Otis. Remarkably, all three scientists had worked in very dissimilar areas of physiology before and, by their own admission, were largely ignorant of respiratory physiology. However, because of the exigencies of war they were brought together to study the physiology of pressure breathing. The result was that they laid much of the foundations of pulmonary gas exchange and pulmonary mechanics and some of their work is still cited today. In pulmonary gas exchange they exploited the new oxygen-carbon dioxide diagram; clarified the effects of changes of altitude, hyperventilation, and pressure breathing; and pioneered the analysis of ventilation-perfusion relationships. In respiratory mechanics, they carried out groundbreaking work on the pressure-volume behavior of the lung and chest wall and went on to analyze aspects of gas flow and work of breathing. This explosion of ideas from what initially appeared to be a poorly prepared group has lessons for us today.
Common Fixed Points, Invariant Approximation and Generalized Weak Contractions
Authors: Chandok Sumit
Published: October 2012

Sufficient conditions for the existence of a common fixed point of generalized -weakly contractive noncommuting mappings are derived. As applications, some results on the set of best approximation for this class of mappings are obtained. The proved results generalize and extend various known results in the literature.
Study of Ruthenium Complex Sensitizer and Gold Nanoparticles Doped Flexible Organic Solar Cells
Authors: Chen Cheng-Chiang , Chen Lung-Chien
Published: October 2012

This work presents a flexible organic solar cell with a structure for ITO/PEDOT:PSS/P3HT:PCBM+ruthenium complex sensitizer and Au nanoparticles on a flexible substrate. The process and thickness of the PEDOT:PSS hole transport layer and P3HT:PCBM active layer were optimized. A ruthenium complex sensitizer and Au nanoparticles were then introduced into the P3HT:PCBM active layer to improve the performance of solar cells. For the ITO/PEDOT:PSS/P3HT:PCBM+ruthenium complex sensitizer and Au nanoparticles structure on a flexible polyimide (PI) substrate under 0.1 and 1 sun conditions, the measured short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), and efficiency (η) are 3.89 and 9.67 mA/cm2, 0.45 and 0.45 V, 0.266 and 0.232, and 4.65 and 1.01%, respectively.
Investigating the Effect of In Ovo Injection of Silver Nanoparticles on Fat Uptake and Development in Broiler and Layer Hatchlings
Authors: Pineda Lane , Chwalibog André , Sawosz Ewa , Hotowy Anna , Elnif Jan , Sawosz Filip
Published: October 2012

Silver nanoparticles (AgNano) as carrier of available oxygen (O2) and with high surface reactivity may increase O2consumption, enhance fat uptake (FU), and stimulate growth and development. The objective was to investigate the effects of in ovo injection of AgNano on the metabolic rate (O2consumption, CO2production, and heat production, HP), fat uptake, and the development of broiler and layer hatchlings. AgNano concentrations (50, 75, and 100 mg/kg) were injected in ovo at day 1 of incubation to different breeds of broiler and layer chicken embryos. Oxygen consumption and subsequently FU did not increase linearly following AgNano treatment. FU was lower in hatchlings treated with 50 and 100 mg AgNano/kg, but surprisingly not in hatchlings treated with 75 mg AgNano/kg. Interestingly, the difference in FU between treatments was not reflected in hatchling development. The results indicated that AgNano affected metabolic rate and FU; however, it did not influence the development of hatchlings. This suggests that in ovo injection of AgNano reduces the need to use yolk fat as an energy source during embryonic development and consequently the remaining fat in the residual yolk sac may provide a potent source of nutritional reserves for chicks of few days after hatching.
Approximate Riesz Algebra‐Valued Derivations
Authors: Polat Faruk
Published: October 2012

Let F be a Riesz algebra with an extended norm ||·||u such that (F, ||·||u) is complete. Also, let ||·||v be another extended norm in F weaker than ||·||u such that whenever (a) xn → x and xn · y → z in ||·||v, then z = x · y; (b) yn → y and x · yn → z in ||·||v, then z = x · y. Let ε and δ> be two nonnegative real numbers. Assume that a map f : F → F satisfies | | f(x + y) − f(x) − f(y) | |u ≤ ε and | | f(x · y) − x · f(y) − f(x) · y | |v ≤ δ for all x, y ∈ F. In this paper, we prove that there exists a unique derivation d : F → F such that | | f(x) − d(x) | |u ≤ ε, (x ∈ F). Moreover, x · (f(y) − d(y)) = 0 for all x, y ∈ F.
Synchronized Hopf Bifurcation Analysis in a Delay‐Coupled Semiconductor Lasers System
Authors: Zhu Gang , Wei Junjie
Published: October 2012

The dynamics of a system of two semiconductor lasers, which are delay coupled via a passive relay within the synchronization manifold, are investigated. Depending on the coupling parameters, the system exhibits synchronized Hopf bifurcation and the stability switches as the delay varies. Employing the center manifold theorem and normal form method, an algorithm is derived for determining the Hopf bifurcation properties. Some numerical simulations are carried out to illustrate the analysis results.
Deficient Knowledge on Hepatitis B Infection in Pregnant Women and Prevalence of Hepatitis B Surface Antigen Carriage in an Endemic Area: A Review
Authors: Chan Oi Ka , Lao Terence T. , Suen Stephen S. H. , Leung Tak Yeung
Published: October 2012

Hepatitis B infection is a major global health problem. Vertical transmission is the commonest route of spreading hepatitis B virus (HBV) in many endemic areas. In order to control such transmission in Hong Kong, neonatal immunization programme was implemented for more than two decades. A declining prevalence of HBV infection was expected. However, the prevalence remained unabated at around 10% in recent studies. We suspect that one of the explanations of this persistent high prevalence is deficient knowledge on infection with the HBV and its prevention. Our paper gives an overview of the knowledge on HBV infection among Chinese population in both high and low endemic areas and discusses the potential factors that influenced the knowledge on as well as the implication of the sources of information for HBV infection, which was not addressed in previous studies.
Necessary and Sufficient Condition for Mann Iteration Converges to a Fixed Point of Lipschitzian Mappings
Authors: Xiang Chang-He , Zhang Jiang-Hua , Chen Zhe
Published: October 2012

Suppose that E is a real normed linear space, C is a nonempty convex subset of E, T : C → C is a Lipschitzian mapping, and x* ∈ C is a fixed point of T. For given x0 ∈ C, suppose that the sequence {xn} ⊂ C is the Mann iterative sequence defined by xn+1 = (1 − αn)xn + αnTxn, n ≥ 0, where {αn} is a sequence in [0, 1], , . We prove that the sequence {xn} strongly converges to x* if and only if there exists a strictly increasing function Φ : [0, ∞)→[0, ∞) with Φ(0) = 0 such that .