bluuebunny/crossref_metadata_2025 huggingface dataset:
A global comparison of grassland biomass responses to CO
2
and nitrogen enrichment
Authors: Lee Mark , Manning Pete , Rist Janna , Power Sally A. , Marsh Charles
Published: May 2010

Grassland ecosystems cover vast areas of the Earth's surface and provide many ecosystem services including carbon (C) storage, biodiversity preservation and the production of livestock forage. Predicting the future delivery of these services is difficult, because widespread changes in atmospheric CO
2
concentration, climate and nitrogen (N) inputs are expected. We compiled published data from global change driver manipulation experiments and combined these with climate data to assess grassland biomass responses to CO
2
and N enrichment across a range of climates. CO
2
and N enrichment generally increased aboveground biomass (AGB) but effects of CO
2
enrichment were weaker than those of N. The response to N was also dependent on the amount of N added and rainfall, with a greater response in high precipitation regions. No relationship between response to CO
2
and climate was detected within our dataset, thus suggesting that other site characteristics, e.g. soils and plant community composition, are more important regulators of grassland responses to CO
2
. A statistical model of AGB response to N was used in conjunction with projected N deposition data to estimate changes to future biomass stocks. This highlighted several potential hotspots (e.g. in some regions of China and India) of grassland AGB gain. Possible benefits for C sequestration and forage production in these regions may be offset by declines in plant biodiversity caused by these biomass gains, thus necessitating careful management if ecosystem service delivery is to be maximized. An approach such as ours, in which meta-analysis is combined with global scale model outputs to make large-scale predictions, may complement the results of dynamic global vegetation models, thus allowing us to form better predictions of biosphere responses to environmental change.
Association of adiponectin, interleukin (IL)-1ra, inducible protein 10, IL-6 and number of islet autoantibodies with progression patterns of type 1 diabetes the first year after diagnosis
Authors: Kaas A , Pfleger C , Hansen L , Buschard K , Schloot N C , Roep B O , Mortensen H B
Published: May 2010

The progression of type 1 diabetes after diagnosis is poorly understood. Our aim was to assess the relation of disease progression of juvenile-onset type 1 diabetes, determined by preserved beta cell function the first year after diagnosis, with systemic cytokine concentrations and number of autoantibodies. Juvenile patients (n = 227) had a meal-stimulated C-peptide test 1 and 6 months after diagnosis. On the basis of the C-peptide course for the duration of 1–6 months, four progression groups were defined: patients with persistently low beta cell function (‘stable-low’), rapid progressers, slow progressers and remitters. Serum concentrations of adiponectin, interleukin (IL)-1ra, inducible protein 10 (IP-10), IL-6 and glutamic acid decarboxylase (GAD), IA-2A and islet-cell antibodies (ICA) were measured at 1, 6 and 12 months. We found that adiponectin concentrations at 1 month predicted disease progression at 6 months (P = 0·04). Patients with low adiponectin had a higher probability of becoming remitters than rapid progressers, odds ratio 3·1 (1·3–7·6). At 6 and 12 months, adiponectin differed significantly between the groups, with highest concentrations among stable-low and rapid progressers patients (P = 0·03 and P = 0·006). IL-1ra, IP-10 and IL-6 did not differ between the groups at any time-point. The number of autoantibodies differed significantly between the groups at 1 month (P = 0·04), where rapid progressers had the largest number. There was no difference between the groups in human leucocyte antigen-associated risk. We define progression patterns distinguishing patients diagnosed with low beta cell function from those with rapid decline, slow decline or actual increase in beta cell function, pointing to different mechanisms of disease progression. We find that adiponectin concentration at 1 month predicts, and at 6 and 12 months associates with, distinct progression patterns.
Cuticular melanisation and immune response in a butterfly: local adaptation and lack of correlation
Authors: KARL ISABELL , HOFFMANN KLAUS H. , FISCHER KLAUS
Published: May 2010

1. Despite growing knowledge on the relationship between ecological variables and individual immune function, data on the spatial variability of immune defence in invertebrate natural populations are scarce.

2. Here, we use replicated populations of the butterfly Lycaena tityrus from different altitudes to investigate genetic variation in the melanin‐based encapsulation response. As high‐ and low‐altitude populations differ in cuticular pupal melanisation, we further tested for any associations between pupal melanisation and parasite resistance.

3. Although pupal melanisation was higher at higher compared with lower altitudes (and at a higher compared with a lower rearing temperature), any obvious relations to the encapsulation response were absent. Further phenotypic correlations within groups were significant in one out of four cases only, suggesting that in L. tityrus encapsulation operates largely independent of cuticular melanisation.

4. A significant interaction between altitude and temperature indicated that high‐altitude animals show a stronger melanisation response than low‐altitude ones at the lower temperature and vice versa, indicating local adaptation to different climates.
Habitat utilisation, growth and predation of Cucumaria frondosa: implications for an emerging sea cucumber fishery
Authors: SO J. J. , HAMEL J.‐F. , MERCIER A.
Published: May 2010

Abstract  Biological traits of the sea cucumber Cucumaria frondosa (Gunnerus) relevant to both ecological and management perspectives were investigated in the Newfoundland region. Abundance, size and fitness of adults were maximal on hard substrates. Larvae settled ∼5 weeks post‐spawning and juveniles reached a maximum length of 6 mm after 24 months. Additional size classes of sea cucumbers kept under natural environmental conditions exhibited slow seasonal growth attuned to phytoplankton blooms, indicating that ∼25 years may be required to reach market size. Juveniles of the predator sea star Solaster endeca (L.) readily fed upon 1.5‐2 mm long sea cucumbers. Predation rates on adult C. frondosa by adult S. endeca were modulated by temperature and biased towards injured specimens, suggesting that trawling may exacerbate predation pressure. The combination of slow growth and high predatory pressure enhanced by fishing activities emphasises the need for precautionary management of this emerging fishery in Atlantic Canada.
Genetic and biochemical diversity in the HCV NS5B RNA polymerase in the context of interferon α plus ribavirin therapy
Authors: Cao F. , Donlin M. J. , Turner K. , Cheng X. , Tavis J. E.
Published: May 2010

Summary.  The hepatitis C virus (HCV) RNA polymerase (RdRp) may be a target of the drug ribavirin, and it is an object of drug development. Independent isolates of any HCV subtype differ genetically by approximately 10%, but the effects of this variation on enzymatic activity and drug sensitivity are poorly understood. We proposed that nucleotide use profiles (G/U ratio) among subtype 1b RdRps may reflect their use of ribavirin. Here, we characterized how subtype 1b genetic variation affects RNA polymerase activity and evaluated the G/U ratio as a surrogate for ribavirin use during pegylated interferon α and ribavirin therapy. Genetic and biochemical variation in the RdRp was compared between responders who would be largely sensitive to ribavirin and relapsers who would be mostly resistant. There were no consistent genetic differences between responder and relapser RdRps. RNA polymerization, RNA binding and primer usage varied widely among the RdRps, but these parameters did not differ significantly between the response groups. The G/U ratio among a set of subtype 1a RdRps increased rather than decreased following failed therapy, as would be expected if it reflected ribavirin use. Finally, RdRp activity was significantly associated with ALT levels. These data indicate that (i) current genetic approaches cannot predict RNA polymerase behaviour, (ii) the G/U ratio is not a surrogate for ribavirin use, (iii) RdRp activity may contribute to liver disease by modulating viral mRNA and antigen levels, and (iv) drug candidates should be tested against multiple patient‐derived enzymes to ensure widespread efficacy even within a viral subtype.
Successful management of primary nontuberculous mycobacterial infection of hepatic allograft following orthotopic liver transplantation for hepatitis C
Authors: Singhal A. , Gates C. , Malhotra N. , Irwin D.A. , Chansolme D.H. , Kohli V.
Published: May 2010

A. Singhal, C. Gates, N. Malhotra, D.A. Irwin, D.H. Chansolme, V. Kohli. Successful management of primary nontuberculous mycobacterial infection of hepatic allograft following orthotopic liver transplantation for hepatitis C Transpl Infect Dis 2011: 13: 47–51. All rights reserved

Abstract: Nontuberculous mycobacteria are a rare cause of disease in solid organ and hematopoietic stem cell transplant recipients. The impact of mycobacterial infections in transplant recipients necessitates prompt diagnosis and early initiation of therapy. However, diagnosis remains difficult and there is a lack of specific recommendations for the choice of anti‐mycobacterial drugs, duration of therapy, and monitoring of graft function as well as immunosuppression in these patients. Issues involved in the management are illustrated by an index case of hepatic allograft infection due to Mycobacterium avium complex.
Quality of life following high‐intensity focused ultrasound for the treatment of localized prostate cancer: A prospective study
Authors: Shoji Sunao , Nakano Mayura , Nagata Yoshihiro , Usui Yukio , Terachi Toshiro , Uchida Toyoaki
Published: May 2010

Objectives:  To report our health‐related quality of life (QOL) and functional outcomes following high‐intensity focused ultrasound (HIFU) for localized prostate cancer.

Methods:  Data from prostate cancer patients undergoing HIFU at our institution between January 1999 and April 2007 were collected in our prospective database. Standard preoperative and surgical parameters, as well as baseline urinary function, QOL and sexual assessment were included. The Japanese version of the Functional Assessment of Cancer Therapy‐general (FACT‐G), the FACT‐prostate (P) and the International Index of Erectile Function‐5 (IIEF‐5) were used for the functional assessment. These self‐administered questionnaires were collected preoperatively and again at 6, 12 and 24 months postoperatively.

Results:  A total of 326 patients were included in the analysis. Maximum flow rate and residual urine volume were significantly impaired at 6 months (P = 0.010) after HIFU, even if they returned to baseline values at 12 or 24 months after HIFU. The total FACT‐G score significantly improved at 24 months (P = 0.027) after HIFU. At 6, 12 and 24 months after HIFU, 52%, 63% and 78%, respectively, of the patients, not receiving neoadjuvant hormonal therapy, were potent.

Conclusions:  In our experience, functional and QOL outcomes after HIFU therapy for localized prostate cancer are better than those after other treatment modalities.
Phenotype and function of raphe projections to the suprachiasmatic nucleus
Authors: Yamakawa Glenn R. , Antle Michael C.
Published: May 2010

The circadian clock, located in the suprachiasmatic nucleus (SCN), receives a major afferent from the median raphe nucleus (MRN). In the Syrian hamster, only about 50% of the cells giving rise to this afferent contain serotonin. There is mixed evidence as to whether the serotonergic portion of this projection is involved in non‐photic phase shifting of circadian locomotor rhythms. In order to better characterize the non‐serotonergic projections, we conducted retrograde tract tracing using the beta subunit of cholera toxin combined with multi‐label immunohistochemistry. Similar to previous findings, almost half of the retrogradely labeled cells contained serotonin. Additionally, approximately 30% of the retrogradely labeled cells contained vesicular glutamate transporter 3 (VGLUT3), but not serotonin. Surprisingly, some dorsal raphe cholera toxin labeling was also noted, particularly in animals with central‐SCN injections. To determine if the non‐serotonergic projections were important for non‐photic phase shifts elicited by MRN stimulation, the MRN was electrically stimulated in animals pretreated with SCN injection of either the serotonin neurotoxin 5,7‐dihydroxytryptamine or vehicle control. Intact animals phase advanced to midday electrical stimulation of the raphe while lesioned animals did not. Together, these results show that although some of the non‐serotonergic raphe projections to the SCN contain VGLUT3, it is the serotonergic raphe innervation of the SCN that is critical for non‐photic phase shifting elicited by MRN stimulation.
Influence of biofilm formation in the susceptibility of Pseudomonas aeruginosa from Brazilian patients with cystic fibrosis
Authors: FERREIRA ALEX GUERRA , LEÃO ROBSON SOUZA , CARVALHO‐ASSEF ANA PAULA D’ALINCOURT , FOLESCU TANIA WROBEL , BARTH AFONSO LUÍS , MARQUES ELIZABETH ANDRADE
Published: May 2010

Ferreira AG, Leão RS, Carvalho‐Assef APD, Folescu TW, Barth AL, Marques EA. Influence of biofilm formation in the susceptibility of Pseudomonas aeruginosa from Brazilian patients with cystic fibrosis. APMIS 2010; 118: 606–12.

Biofilms play a key role in the occurrence of lung infections by Pseudomonas aeruginosa in patients with cystic fibrosis (CF). In this study, we examined 40 isolates of P. aeruginosa from CF patients according to their capacity to form biofilm. We also compared their in vitro response to antimicrobials according to different modes of growth (planktonic vs biofilm) and performed molecular typing. All isolates proved capable of forming biofilm. However, there was no difference in biofilm development according to the mucoid and nonmucoid phenotypes and among isolates obtained at different periods of the chronic infection. All isolates tested for antimicrobial susceptibility in the biofilm state (BIC) were consistently more resistant to antibiotics than the same isolate tested in the planktonic state. The molecular typing indicates a considerable clonal diversity among isolates. We identified five patients harboring the same strain over different periods. These strains, however, displayed different levels of biofilm formation and BIC values for antibiotics tested. The results of the present study demonstrate that there is a marked difference in the susceptibility profile according to the mode of growth of CF P. aeruginosa, as cells tested in the biofilm state proved consistently more resistant to antibiotics.
Keloid explant culture: a model for keloid fibroblasts isolation and cultivation based on the biological differences of its specific regions
Authors: Tucci‐Viegas Vanina Monique , Hochman Bernardo , França Jerônimo P , Ferreira Lydia M
Published: May 2010

In vitro studies with keloid fibroblasts frequently present contradictory results. This may occur because keloids present distinct genotypic and phenotypic characteristics in its different regions, such as the peripheral region in relation to the central region. We suggest an explant model for keloid fibroblasts harvesting, standardising the initial processing of keloid samples to obtain fragments from different regions, considering its biological differences, for primary cell culture. The different keloid regions were delimited and fragments were obtained using a 3‐mm diameter punch. To remove fragments from the periphery, the punch was placed in one longitudinal line extremity, respecting the lesion borders. For the central region, it was placed in the intersection of lines at the level of the largest longitudinal and transversal axes, the other fragments being removed centrifugally in relation to the first one. Primary fibroblast culture was carried out by explant. Flow cytometry analysis showed cell cycle differences between the groups, confirming its different origins and biological characteristics. In conclusion, our proposed model proved itself efficient for keloid fibroblast isolation from specific regions and cultivation. Its simplicity and ease of execution may turn it into an important tool for studying the characteristics of the different keloid‐derived fibroblasts in culture.
The indexation of periodical payments of damages in tort: the future assured?
Authors: Lewis Richard
Published: May 2010

This paper examines the new statutory regime for paying damages for personal injury by means of periodical payments instead of a lump sum. How are such payments to increase in future to take account of rising care costs, especially when these usually form the largest part of a major award? The answer to this question is crucial in determining the extent that the new form of payment will be used. How periodical payments are to be indexed is also a key factor in calculating the total cost of compensation and, in particular, in assessing the liabilities of the National Health Service. The issue gave rise to litigation which was voted by personal injury practitioners as the most important of the year. Here, that litigation and the statutory reforms which gave rise to it are set in their wider academic contexts.
WT1 Is Not a Reliable Marker to Distinguish Reactive from Neoplastic Astrocyte Populations in the Central Nervous System
Authors: Bourne T. David , Elias W. Jeffrey , Lopes M. Beatriz S. , Mandell James W.
Published: May 2010

A diagnostic difficulty in neuropathology practice is distinguishing reactive from neoplastic astrocyte populations. This is particularly true in small biopsy samples that lack evidence of increased cellularity or mitotic activity, microvascular proliferation, or necrosis. We performed the current study to validate the previously reported finding that in the central nervous system, the expression of WT1 is limited to neoplastic astrocytes. We retrospectively studied WT1 protein expression by immunohistochemistry (IHC) in 100 formalin‐fixed, paraffin‐embedded brain tissue samples consisting of 3 normal control tissues, 44 cases of reactive gliosis, 49 gliomas and 4 lesions suspicious for glioma. In normal human cortex, WT1 staining was restricted to vascular endothelium. Most cases of reactive gliosis (82%) showed at least focal WT1 positivity, and analysis of specimens with electrode monitoring lesions showed an inverse relationship between WT1 expression intensity and the number of days from electrode placement to tissue resection. All glioma samples (100%) and all cases suspicious for glioma (100%) showed at least focal WT1 positivity. Our results likely differ from those in the prior report because of differences in tissue fixation and IHC methodology. Thus, our findings indicate that WT1 expression alone is not a reliable feature to distinguish reactive from neoplastic astrocytes.
A first step towards inferring levels of long‐distance dispersal during past expansions
Authors: RAY NICOLAS , EXCOFFIER LAURENT
Published: May 2010

Improving the realism of spatially explicit demographic models is important for better inferring the history of past populations and for understanding the genetic bases of adaptation and speciation. One particular type of demographic event to take into account is long‐distance dispersal (LDD). The goals of this study are to explore the impact of various levels of LDD on genetic diversity and to show to what extent LDD levels can be correctly inferred from multilocus data sets using an approximate Bayesian computation approach. We therefore incorporated LDD into a 2D stepping stone forward simulation framework coupled to a coalescent backward simulation step to generate genetic diversity at 100 microsatellite markers under various demographic conditions relevant to recent human evolution. Our results confirm that LDD considerably increases genetic diversity within demes and decreases levels of diversity between demes. By controlling the spatial occurrence of LDD, it appears that LDD events occurring during a phase of range expansion into new territories are more important in maintaining genetic diversity than those occurring in the wake of the expansion or when colonization is over. We also show that it is possible to infer whether LDD has occurred during a range expansion, but our results suggest that one can only approximately estimate the extent of LDD based on genetic summary statistics.
Carriage of Clostridium difficile and Other Enteric Pathogens Among a 4‐H Avocational Cohort
Authors: McNamara S. E. , Abdujamilova N. , Somsel P. , Gordoncillo M. J. , DeDecker J. M. , Bartlett P. C.
Published: May 2010

Clostridium difficile (CD), Salmonella, Campylobacter and enterohemorrhagic Escherichia coli (EHEC) are major causes of morbidity in a variety of enteric diseases in humans and animals, but subclinical carriage in both is probably more common than are clinical cases. Little is known regarding the prevalence of these pathogens in animals raised for exhibit at Michigan county fairs or the frequency with which Michigan citizens raising these animals may have been subclinically colonized. To address these issues, 361 fecal specimens from 158 humans and 203 of their farm animals were cultured for CD, Salmonella and Campylobacter. Additionally, 50 people and their cattle were tested for EHEC. No EHEC, Salmonella or Campylobacter were detected. However, 16 specimens (4.4%) were positive for CD: 13 humans, two horses and one pig. None of the farm animal specimens submitted by any of the 13 CD‐positive humans were positive for CD. Strain characterization [toxinotype, pulsed‐field gel electrophoresis (PFGE)] demonstrated that the human CD isolates were similar to what has been reported previously in the general US population. We conclude that horses and farm animals (cattle, sheep, goats and swine) at 1–2 months before market weight showed no evidence of wide‐spread carriage of the common enteric pathogens, including the recently reported CD toxinotype V. These results provide no support to the hypothesis that 4‐H members or others visiting county fair animal husbandry projects in these counties may be at increased risk for acquisition of CD, Salmonella, Campylobacter or EHEC from animals.
AN EFFICIENT LATTICE BOLTZMANN METHOD FOR THE APPLICATION ON NON-UNIFORM CARTESIAN MESH
Authors: SHU CHANG , WU JIE
Published: May 2010

An efficient lattice Boltzmann method (LBM) on non-uniform Cartesian mesh is presented in this work. In the standard LBM, the uniform mesh is used. To well capture the boundary layer and in the meantime, to save computational effort, many efforts have been made to improve the LBM so that it can be implemented on the non-uniform mesh. On the other hand, LBM has been combined with other numerical schemes to simulate complex flows recently. To solve immersed boundary (IB) problem efficiently, a new version of LBM on non-uniform Cartesian mesh is proposed in this study. A second-order local interpolation is used to calculate the distribution function at a position different from mesh points. The numerical results from the simulation of flow over a circular cylinder compare well with the data in literature.
NUMERICAL SIMULATIONS OF VORTEX SHEDDING FROM 2D BLUFF BODIES WITH BASE CAVITIES
Authors: CAI JINSHENG , LIU FENG
Published: May 2010

This paper describes a numerical study of vortex shedding from a quasi-streamlined 2D body with the trailing edge made in the form of a base cavity. Direct numerical simulations (DNS) are conducted to assess the effect of Reynolds number and streamwise cavity length on the flow. It was found that the flow is governed by the formation of a vortex within the base cavity, which either serves to retard or convolute the shedding process. For a shorter cavity length, this vortex is periodically replaced, and the result is a reduction in the shedding frequency and the time-averaged form drag. As the cavity length is increased, this periodic behavior ceases and the vortex which first forms within the cavity remains there permanently throughout the observation. The origins of the deflected wake pattern are traced to the presence of a vortex which resides within the base cavity. Reductions in drag are observed for all the investigated cavity configurations and additionally it is found that the magnitude of the reduction obeys a direct relationship with the length of the cavity up to a certain asymptotic value.
A CELL-CENTERED LAGRANGIAN SCHEME FOR COMPRESSIBLE MULTI-MEDIUM FLOW
Authors: WANG DONGHONG , ZHAO NING , WANG YONGJIAN
Published: May 2010

In this paper, a kind of Godunov-type Lagrangian scheme is developed in the one space dimension. The Riemann problems are constructed at the interface and the velocity and pressure are evaluated using an implicit characteristic method. Two different methods are used to solve for the equation of energy conservation. Four one-dimensional numerical examples are first presented to obtain the parameter through comparison of the L1 errors with the changing parameter values. The method having the minimal error is then extended to two dimensions and a cell-centered conservative Lagrangian scheme is proposed for the compressible multi-medium flow. The numerical results for some classical two dimensional hydrodynamic test cases show that the proposed numerical methods are effective and feasible.
NUMERICAL SIMULATION OF SPRAY ATOMIZATION IN SUPERSONIC FLOWS
Authors: WANG JIANGFENG , LIU CHEN , WU YIZHAO
Published: May 2010

With the rapid development of the air-breathing hypersonic vehicle design, an accurate description of the combustion properties becomes more and more important, where one of the key techniques is the procedure of the liquid fuel mixing, atomizing and burning coupled with the supersonic crossflow in the combustion chamber. The movement and distribution of the liquid fuel droplets in the combustion chamber will influence greatly the combustion properties, as well as the propulsion performance of the ramjet/scramjet engine. In this paper, numerical simulation methods on unstructured hybrid meshes were carried out for liquid spray atomization in supersonic crossflows. The Kelvin-Helmholtz/Rayleigh-Taylor hybrid model was used to simulate the breakup process of the liquid spray in a supersonic crossflow with Mach number 1.94. Various spray properties, including spray penetration height, droplet size distribution, were quantitatively compared with experimental results. In addition, numerical results of the complex shock wave structure induced by the presence of liquid spray were illustrated and discussed.
CONTINUOUS NEWTON METHOD FOR NONLINEAR PARTIAL DIFFERENTIAL EQUATION
Authors: CAI Q.-D.
Published: May 2010

Newton method is a widely used iteration method in solving nonlinear algebraic equations. In this method, a linear algebraic equations need to be solved in every step. The coefficient matrix of the algebraic equations is so-called Jacobian matrix, which needs to be determined at every step. For a complex non-linear system, usually no explicit form of Jacobian matrix can be found. Several methods are introduced to obtain an approximated matrix, which are classified as Jacobian-free method. The finite difference method is used to approximate the derivatives in Jacobian matrix, and a small parameter is needed in this process. Some problems may arise because of the interaction of this parameter and round-off errors. In the present work, we show that this kind of Newton method may encounter difficulties in solving non-linear partial differential equation (PDE) on fine mesh. To avoid this problem, the continuous Newton method is presented, which is a modification of classical Newton method for non-linear PDE.
CHARACTERISTICS OF CAVITY IN REACTING FLOWS FOR SCRAMJET FLAME-HOLDER APPLICATION
Authors: LIU OUZI , CAI JINSHENG
Published: May 2010

During the last few years, cavities have gained attention in the scramjet community as a promising flame-holding device. The present simulation study attempts to understand the reacting flow cavity characteristics for scramjet flame-holder application. The fuel was injected from upstream of cavity in reacting flow. Effects of cavity length to depth ratio were investigated. As the ratio of length-to-depth (L/D) is 3 or 4, the distribution form of the floor static-pressure of cavity in reacting flow is not consistent with that of cavity in non-reacting flow, even though open cavity flow occurs for the two cases. Open cavity flow occurs for L/D = 5, 6, 7 and 8 in non-reacting flow. Transitional cavity flow occurs for L/D = 5, 6 and 7, and closed cavity flow occurs for L/D = 8 in reacting flow. The flame holding capability of cavity with L/D = 7 is the best among all the cavities by comparison of the recirculation dimensions. Considering the drag of cavity, the cavity with ratio L/D = 5 is the best flame-holder among all cavities. The simulation results demonstrate that the cavity characteristics is different in non-reacting and reacting flows, and the conventional definition of cavity flow characteristics based on non-reacting flows needs to be revised accordingly.
SIMULATION OF PIEZOELECTRIC JELLYFISH POWER GENERATOR
Authors: WU YEONG-JEN , LAI WEI-HSIANG
Published: May 2010

The energy problem is getting increasingly serious. As such, unused energy recovery technology is crucial for environmental protection, which has been investigated extensively. Several methods have been developed to utilize scavenged energy from the environment, such as waste heat, solar energy, wind energy, and tides energy to convert into useful power. There is a new idea of piezoelectric jellyfish generator which combines the utilization of sea wave and vibration energy. When sea wave passes through the jellyfish, the wave causes the tentacles to vibrate. The tentacles is made of piezoelectric polymer which can convert the strain energy into electrical energy. This paper discusses about the piezoelectric jellyfish's tentacles being disturbed by wave in the sea. We employed the commercial CFD software CFD-ACE+ 2006 to simulate this phenomenon. The parameters including its tentacle length (L) and wave propagating function (Y) are studied which affect the piezoelectric jellyfish capacity to generate power.
APPLICATION OF ADAPTIVE MESH REFINEMENT IN NUMERICAL SIMULATION OF GAS DETONATION
Authors: WANG CHENG , MA TIANBAO
Published: May 2010

In this paper the two-dimensional Euler equations, with a simple chemical reaction model, are used as the governing equations for the detonation problem. The spatial derivatives are evaluated using the fifth-order WENO scheme, and the third-order TVD Runge-Kutta method is employed for the temporal derivative. The characteristics of the two-dimensional detonation in an argon-diluted mixture of hydrogen and oxygen are investigated using Adaptive Mesh Refinement (AMR) method. From computational accuracy point of view, AMR enables the detonation front to be clearer than the method with basic meshes. From the other point of computational time, AMR also saves about half the time as compared with the case of refining the entire field. It is obvious that AMR not only increases the resolution of local field, but also improves the efficiency of numerical simulation.
COMPUTATIONAL INVESTIGATION OF THERMAL PLASMAS IN A SF6 CHAMBER WITH DIFFERENT APPLIED CURRENTS
Authors: LEE J. C. , KIM Y. J.
Published: May 2010

In this study, we predicted the thermal breakdown of high-voltage interrupter with the characteristics of thermal plasmas such as temperature, pressure and concentration of the ablated material by using a commercial CFD program. The results showed that the pressure build-up inside the chamber was proportional to the magnitude of applied current because the quantities of heat energy and ablated mass also increase together with the current during the compression process. During the decompression process, the reverse flow found did not coincide with the magnitude of current due to the compressibility of the gas through backflow channel. The present method is expected to be useful for the design of guideline and interruption capacity on the thermal breakdown of a PASB chamber.
TURBULENCE MODELS FOR ACCURATE AEROTHERMAL PREDICTION IN HYPERSONIC FLOWS
Authors: ZHANG XIANG-HONG , WU YI-ZAO , WANG JIANG-FENG
Published: May 2010

Accurate description of the aerodynamic and aerothermal environment is crucial to the integrated design and optimization for high performance hypersonic vehicles. In the simulation of aerothermal environment, the effect of viscosity is crucial. The turbulence modeling remains a major source of uncertainty in the computational prediction of aerodynamic forces and heating. In this paper, three turbulent models were studied: the one-equation eddy viscosity transport model of Spalart-Allmaras, the Wilcox k -ω model and the Menter SST model. For the k -ω model and SST model, the compressibility correction, press dilatation and low Reynolds number correction were considered. The influence of these corrections for flow properties were discussed by comparing with the results without corrections. In this paper the emphasis is on the assessment and evaluation of the turbulence models in prediction of heat transfer as applied to a range of hypersonic flows with comparison to experimental data. This will enable establishing factor of safety for the design of thermal protection systems of hypersonic vehicle.
PARALLEL SIMULATION OF EXPLOSION IN AN UNLIMITED ATMOSPHERE
Authors: MA TIANBAO , WANG CHENG , FEI GUANGLEI , NING JIANGUO
Published: May 2010

In this paper, a parallel Eulerian hydrocode for the simulation of large scale complicated explosion and impact problem is developed. The data dependency in the parallel algorithm is studied in particular. As a test, the three dimensional numerical simulation of the explosion field in an unlimited atmosphere is performed. The numerical results are in good agreement with the empirical results, indicating that the proposed parallel algorithm in this paper is valid. Finally, the parallel speedup and parallel efficiency under different dividing domain areas are analyzed.
ENHANCEMENT ON PROPULSION PERFORMANCE: MODIFYING ANGLE OF ATTACK PROFILE
Authors: XIAO QING , LIAO WEI , DOU HUA-SHU
Published: May 2010

In this paper, numerical investigation was conducted for an oscillating NACA0012 foil combining the pitching and plunging motions. The plunging follows a sinusoidal motion while the pitching trajectory is controlled by achieving the resultant effective angle of attack (AOA) to be a harmonic cosine form. Computations were conducted over a range of the Strouhal number (St), different maximum effective AOA and different phase difference between pitching and plunging (ψ). Results show that, at higher St, significant improvement on propulsion performance has been achieved when the effective AOA profile maintains a harmonic cosine form by controlling the pitching motion of the foil.
EXPERIMENTAL INVESTIGATION OF VELOCITY AUTOCORRELATION FUNCTIONS IN TURBULENT PLANAR MIXING LAYER
Authors: CHANG KEH-CHIN , LI CHIUAN-TING , CHEN HSUAN-JUNG
Published: May 2010

The velocity autocorrelation coefficient correlates the velocity in the time domain but at the same spatial position. Turbulent planar mixing layer consists of two types of turbulence, that is, shear turbulence in the central shear layer and nearly homogeneous turbulence in both the high- and low-speed free stream sides. It is interesting to know what kind of function forms can be used to represent faithfully the experimental observations of the velocity autocorrelation coefficients in the mixing layer. Various velocity autocorrelation functions are tested with the measured data. It is found that the Frenkiel function family is the most proper form to represent the measured velocity autocorrelation coefficients in both the shear layer and free stream regimes.
THE DYNAMICS OF AN OSCILLATING BUBBLE NEAR BIO-MATERIALS
Authors: OHL SIEW-WAN , KLASEBOER EVERT , KHOO BOO CHEONG
Published: May 2010

The simulation of an oscillating bubble near various bio-materials (brain and cornea) using the Boundary Element Method (BEM) is presented. The bio-materials are modeled as an elastic fluid with different Young's modulus and density. It is found that the bubble tends to split into two or more bubbles when it is oscillating near soft bio-materials (such as brain). The bubble will collapse with a high speed jet (about 100 m/s) near hard bio-materials (such as cornea). It is found from simulation that under certain conditions (light and soft elastic material), the oscillating bubble will jet away from the elastic boundary similar to a bubble near a free surface. An experiment using a laser generated bubble is carried out to confirm this phenomenon.
INVESTIGATION ON STABILITY IN ROLL OF SQUARE SECTION MISSILE AT HIGH ANGLE OF ATTACK
Authors: TAO YANG , FAN ZHAOLIN , WU JIFEI , WU WENHUA
Published: May 2010

An experimental investigation of the stability in roll of a square section missile at high incidence was conducted in FL-23 wind tunnel. Dynamic motions were obtained on a square section missile that is free to rotate about its longitudinal axis. Different dynamic rolling motions were observed depending on the incidence of the model sting. These dynamic regimes include damped oscillations, quasi-limit-cycle wing-rock motion, and constant rolling. A coupling numerical method was established by solving the fluid dynamics equations and the rigid-body dynamics equations synchronously in order to predict the onset and the development of uncommented motions and then explore the unsteady movement characteristics of the aircraft. The study indicates that the aircraft loss stability at high incidence is caused by the asymmetric vertex on the level fin tip liftoff and attach alternately. The computation results are in line with the experiment results.
EFFECT OF DORSAL FIN ON THE STABILITY OF VORTICES OVER A DELTA WING
Authors: MENG XUANSHI , QIAO ZHIDE , GAO CHAO , LUO SHIJUN , LIU FENG
Published: May 2010

Cai et al.5 developed a vortex stability theory for slender conical bodies and analyzed the stability of vortex pairs over slender conical wing-body combinations under small perturbations. An experimental study is presented in this paper to verify the validity of the theoretical predictions. A sharp-edged flat-plate delta wing is tested in a low-speed wind tunnel. A smoke-laser-sheet visualization technique is used to visualize and measure the positions of the vortex pair, which are found to be symmetric and conical over the wing. The same tests are performed on an identical delta wing model but with a flat-plate dorsal fin mounted vertically in the incidence plane of the wing. Two fin heights are tested. The ratios of the local fin height to the local wing semi-span are 0.75 and 1.50. The test results clearly indicate that the vortices become asymmetric and non-conical over the model with the fin height ratio of 0.75 and recover symmetry and conicity over the model with the fin height ratio of 1.50, providing direct experimental evidence of the theoretical predictions.
PARTICLE TRANSPORT ACROSS BI-FLUID INTERFACE USING ACOUSTIC RADIATION FORCE
Authors: LIU YANG , LIM KIAN-MENG
Published: May 2010

A bi-fluid micro-flow system is proposed for separating particles from its original solvent and re-diluting them into another solvent simultaneously. In this micro-flow system, two different miscible solvents flow parallel to each other through a 2-inlet-2-outlet micro-channel, where an acoustic standing wave is set up. Due to the differences in acoustic properties of these solvents, the pressure node of the acoustic wave is shifted from the middle line of the channel. Under the action of the acoustic radiation force, particles with positive ϕ-factors are extracted from their original solvent and re-suspended into the other solvent, wherein the pressure node resides. Particles suspended in the new solvent are collected at one of the two outlets downstream. Experiments were conducted on a prototype using two aqueous solutions: deionized water and 40% glycerin aqueous solution with polystyrene micro-particles. The results show that under the action of the acoustic standing wave, most of the particles were successfully transported from its original solvent to the other solvent and collected at the outlet.
CHARACTERISTICS OF FORE-BODY SEPARATE FLOW AT HIGH ANGLE OF ATTACK UNDER PLASMA CONTROL
Authors: WANG JIANLEI , LI HUAXING , LIU FENG , LUO SHIJUN
Published: May 2010

A pair of plasma actuators with horseshoe shape is proposed for dynamic manipulation of forebody aerodynamic load at high angles of attack. Preliminary wind tunnel pressure measurements show that asymmetric force over a conical forebody with semi-apex angle 10° can be manipulated by activating the plasma actuator mounted on one side of the cone tip. Further work is suggested.
INVESTIGATION ON AEROACOUSTIC CHARACTERISTICS IN CAVITY FLOW
Authors: WU JIFEI , FAN ZHAOLIN , TAO YANG
Published: May 2010

An experiment was conducted in a high speed wind tunnel to study the effects of dynamic pressure waves in a cavity from subsonic speeds to supersonic speeds. The effects on dynamic pressure of various parameters such as the Mach number, cavity length to depth ratio and the number of generic store were demonstrated. Detailed static-pressure and fluctuating pressure were measured on the cavity floor to determine the variation of the steady and unsteady pressures. Results show that cavity flow aero-acoustic characteristics are closely related to the Mach number and the cavity length to depth ratio. It is also found that installing store/stores in cavity can effectively improve the aero-acoustic environment in the cavity.
MULTI-SCALE STRUCTURES IN COMPRESSIBLE TURBULENT MIXING LAYERS
Authors: WANG TIE-JIN , SHI XIAO-TIAN , CHEN JUN , SHE ZHEN-SU
Published: May 2010

A size-dependent gradient method is used to study the Mie scattering visualization of the compressible turbulent mixing layers at two convective Mach numbers Mc = 0.107 and 0.474 in order to reveal multi-scale structures. Coherent vortices and inclined wavy structures are clearly visualized by applying the method. Similarity between the grey-level and the velocity fluctuations is discovered with the spectral analysis. These results suggest a way to capture turbulent structures from scalar fields.
PHYSICS OF COHERENT STRUCTURES OF TURBULENT FLOW IN NEAR-WALL REGION OF A VIBRATING PLATE
Authors: ZHANG L. X.
Published: May 2010

The focus of this paper is on physics of coherent structures in boundary layer flow in near-wall region of a vibrating plate. A dynamical model is developed based on Galerkin projection of the governing equation of the wall layer flow onto a subspace spanned by the orthogonal divergence-free Fourier basis functions. The interactive physics of the coherent structures with the wall vibration is studied with the established model truncated at any order. The compared results show that the prevailing coherent structures in the layer flow near a vibrating wall region are captured.
RESONANCE OF NONMODAL PERTURBATIONS IN THE BATCHELOR VORTEX
Authors: GUO ZHI-WEI , SUN DE-JUN
Published: May 2010

The resonance phenomenon for nonmodal perturbation of Batchelor vortex is studied. For azimuthal wavenumber n = - 1, two resonant peaks appear and the left one is always dominant. For n = 1, the resonant character becomes very complicated. There is a resonant mode switch from right peak to left peak as swirl parameter q increases from 2 to infinity. The resonant wavenumber k is the largest when q approaches to infinity for n = - 1 while it is the smallest for n = 1. The maximum value of the optimal energy growth for n = 1 is at q approaches to infinity, whereas it decreases monotonically as q increases for n = - 1. The resonance for n = - 1 is the more important one.
LARGE EDDY SIMULATION OF COMPRESSIBLE TURBULENT CHANNEL FLOW WITH ACTIVE SPANWISE WALL FLUCTUATIONS
Authors: FANG JIAN , LU LIPENG
Published: May 2010

The large eddy simulation (LES) of compressible turbulent channel flow controlled by active spanwise wall fluctuations (ASWF) is carried out in this paper. Heat transport and its relation with the momentum transport are paid with great attentions. In all the flow cases of present study, the changes of temperature fluctuation, heat transport and temperature streaks are in consistence with streamwise velocity fluctuation, momentum transport and velocity streaks respectively. This demonstrates the existence of same mechanism in heat transport and momentum transport in turbulent boundary layer, which gives the theoretical support for using the drag reduction technology to control wall heat flux.
NUMERICAL ANALYSIS ON THE MECHANICAL PROPERTIES OF ORGANIC THIN FILM TRANSISTOR
Authors: LEE S. C. , LEE D. K. , SEOL Y. G. , AHN J. H. , LEE N. E. , KIM Y. J.
Published: May 2010

The organic thin film transistor (OTFT) on flexible substrate electroplated electrodes has many advantages as in the fabrication of low cost sensors, e-paper, smart cards, and flexible displays. In this study, we simulated the mechanical and electrical characteristics of the OTFT with various voltage conditions by using COMSOL. The model consisting of a channel, source and drain was employed to investigate the temperature distribution and thermal stress concentration. The channel length is 40 µm and the voltage ranged between -20V and -40V. The OTFT was fabricated using pentacene as a semiconducting layer and electroplated Ni as a gate electrode. Mechanical properties of the fabricated OTFT were characterized by thermal stress which was predicted with the result of stress distribution.
FLUID-STRUCTURE INTERACTION ANALYSIS OF HINGELESS ROTOR BLADES IN HOVER CONSIDERING WAKE EFFECTS
Authors: YOO SEUNG-JAE , JEONG MIN-SOO , LEE IN
Published: May 2010

Aeroelastic analysis of hingeless rotor blades in hover was performed. Large deflection beam theory was applied to analyze blade motions with effects of geometric structural nonlinearity. Aerodynamic loads for aeroelastic analysis were calculated through a three-dimensional aerodynamic model which is based on the unsteady vortex lattice method. Wake geometry was described using a time-marching free-wake method. Lead-lag damping ratio and frequency were calculated to evaluate aeroelastic stability of hingeless rotor system. Numerical results of aeroelastic analysis for hingeless rotor blades were presented and compared with results based on experimental data and two-dimensional quasi-steady strip theory in which uniform inflow model was used. It was shown that wakes significantly affect the steady-state deflections and aeroelastic stability.
RESEARCH PROGRESS ON PREDICTION MODELS FOR PHYSICAL PROPERTIES OF IONIC LIQUID
Authors: WANG QUAN , WU XIAO MING , ZHANG DA YONG
Published: May 2010

The field of ionic liquid has gained rapid growth in recent years and occupied a forefront in green chemistry. As a useful instrument to the research and development of novel ionic liquids, the physical properties are of utmost importance. Thus, great efforts have been made to obtain these important data, as it is far from getting sufficient physiochemical information for intensive and extensive investigation which consequently becomes a bottleneck for the theoretical and applicable research of ionic liquids. Additionally, with the given immeasurable possible ionic liquids by various cation and anion combinations, it is an impossible task to find an ideal ionic liquid with desired physical properties using conventionally "try and error" process. For these reasons, exploration of novel prediction models for physical properties of ionic liquid is imperative. This paper gives an overview of recent progress of various prediction models.