bluuebunny/crossref_metadata_2025 huggingface dataset:
Genomic and functional characterizations of phosphodiesterase subtype 4D in human cancers
Authors: Lin De-Chen , Xu Liang , Ding Ling-Wen , Sharma Arjun , Liu Li-Zhen , Yang Henry , Tan Patrick , Vadgama Jay , Karlan Beth Y. , Lester Jenny , Urban Nicole , Schummer Michèl , Doan Ngan , Said Jonathan W. , Sun Hongmao , Walsh Martin , Thomas Craig J. , Patel Paresma , Yin Dong , Chan Daniel , Koeffler H. Phillip
Published: March 2013

Discovery of cancer genes through interrogation of genomic dosage is one of the major approaches in cancer research. In this study, we report that phosphodiesterase subtype 4D (PDE4D) gene was homozygously deleted in 198 cases of 5,569 primary solid tumors (3.56%), with most being internal microdeletions. Unexpectedly, the microdeletions did not result in loss of their gene products. Screening PDE4D expression in 11 different types of primary tumor samples (
n
= 165) with immunohistochemistry staining revealed that its protein levels were up-regulated compared with corresponding nontransformed tissues. Importantly, depletion of endogenous PDE4D with three independent shRNAs caused apoptosis and growth inhibition in multiple types of cancer cells, including breast, lung, ovary, endometrium, gastric, and melanoma, which could be rescued by reexpression of PDE4D. We further showed that antitumor events triggered by PDE4D suppression were lineage-dependently associated with Bcl-2 interacting mediator of cell death (BIM) induction and microphthalmia-associated transcription factor (MITF) down-regulation. Furthermore, ectopic expression of the PDE4D short isoform, PDE4D2, enhanced the proliferation of cancer cells both in vitro and in vivo. Moreover, treatment of cancer cells with a unique specific PDE4D inhibitor, 26B, triggered massive cell death and growth retardation. Notably, these antineoplastic effects induced by either shRNAs or small molecule occurred preferentially in cancer cells but not in nonmalignant epithelial cells. These results suggest that although targeted by genomic homozygous microdeletions, PDE4D functions as a tumor-promoting factor and represents a unique targetable enzyme of cancer cells.
An initial and rapid step of lytic granule secretion precedes microtubule organizing center polarization at the cytotoxic T lymphocyte/target cell synapse
Authors: Bertrand Florie , Müller Sabina , Roh Kyung-Ho , Laurent Camille , Dupré Loïc , Valitutti Salvatore
Published: March 2013

It is presently assumed that lethal hit delivery by cytotoxic T lymphocytes (CTLs) is mechanistically linked to centrosome polarization toward target cells, leading to dedicated release of lytic granules within a confined secretory domain. Here we provide three lines of evidence showing that this mechanism might not apply as a general paradigm for lethal hit delivery. First, in CTLs stimulated with immobilized peptide–MHC complexes, lytic granules and microtubule organizing center localization into synaptic areas are spatio-temporally dissociated, as detected by total internal reflection fluorescence microscopy. Second, in many CTL/target cell conjugates, lytic granule secretion precedes microtubule polarization and can be detected during the first minute after cell–cell contact. Third, inhibition of microtubule organizing center and centrosome polarization impairs neither lytic granule release at the CTL synapse nor killing efficiency. Our results broaden current views of CTL biology by revealing an extremely rapid step of lytic granule secretion and by showing that microtubule organizing center polarization is dispensable for efficient lethal hit delivery.
Mining the antibodyome for HIV-1–neutralizing antibodies with next-generation sequencing and phylogenetic pairing of heavy/light chains
Authors: Zhu Jiang , Ofek Gilad , Yang Yongping , Zhang Baoshan , Louder Mark K. , Lu Gabriel , McKee Krisha , Pancera Marie , Skinner Jeff , Zhang Zhenhai , Parks Robert , Eudailey Joshua , Lloyd Krissey E. , Blinn Julie , Alam S. Munir , Haynes Barton F. , Simek Melissa , Burton Dennis R. , Koff Wayne C. ,   NISC Comparative Sequencing Program, Mullikin James C. , Mascola John R. , Shapiro Lawrence , Kwong Peter D. , Becker Jesse , Benjamin Betty , Blakesley Robert , Bouffard Gerry , Brooks Shelise , Coleman Holly , Dekhtyar Mila , Gregory Michael , Guan Xiaobin , Gupta Jyoti , Han Joel , Hargrove April , Ho Shi-ling , Johnson Taccara , Legaspi Richelle , Lovett Sean , Maduro Quino , Masiello Cathy , Maskeri Baishali , McDowell Jenny , Montemayor Casandra , Mullikin James , Park Morgan , Riebow Nancy , Schandler Karen , Schmidt Brian , Sison Christina , Stantripop Mal , Thomas James , Thomas Pam , Vemulapalli Meg , Young Alice
Published: March 2013

Next-generation sequencing of antibody transcripts from HIV-1–infected individuals with broadly neutralizing antibodies could provide an efficient means for identifying somatic variants and characterizing their lineages. Here, we used 454 pyrosequencing and identity/divergence grid sampling to analyze heavy- and light-chain sequences from donor N152, the source of the broadly neutralizing antibody 10E8. We identified variants with up to 28% difference in amino acid sequence. Heavy- and light-chain phylogenetic trees of identified 10E8 variants displayed similar architectures, and 10E8 variants reconstituted from matched and unmatched phylogenetic branches displayed significantly lower autoreactivity when matched. To test the generality of phylogenetic pairing, we analyzed donor International AIDS Vaccine Initiative 84, the source of antibodies PGT141–145. Heavy- and light-chain phylogenetic trees of PGT141–145 somatic variants also displayed remarkably similar architectures; in this case, branch pairings could be anchored by known PGT141–145 antibodies. Altogether, our findings suggest that phylogenetic matching of heavy and light chains can provide a means to approximate natural pairings.
Candidate tumor suppressor BTG3 maintains genomic stability by promoting Lys63-linked ubiquitination and activation of the checkpoint kinase CHK1
Authors: Cheng Yu-Che , Lin Tsong-Yu , Shieh Sheau-Yann
Published: March 2013

B-cell translocation gene 3(BTG3) is a member of the antiproliferativeBTG/Transducer of ErbB2gene family and is induced by genotoxic stress in a p53- and Checkpoint kinase 1 (CHK1)-dependent manner. Down-regulation of BTG3 has been observed in human cancers, suggesting that it plays an important role in tumor suppression, although the underlying mechanisms are unclear. Here, we report that BTG3 interacts with CHK1, a key effector kinase in the cell cycle checkpoint response, and regulates its phosphorylation and activation. Upon interaction, BTG3 mediates K63-linked ubiquitination of CHK1 at Lys132 through the cullin-RING ligase 4Cdt2E3 complex, thus facilitating CHK1 chromatin association. We show that BTG3-depleted cells phenocopy those CHK1-deficient cells, exhibiting increased cell death after replication block and impaired chromosome alignment and segregation. These defects could be corrected by wild-type BTG3 but not by a mutant impaired in CHK1 interaction. We propose that BTG3-dependent CHK1 ubiquitination contributes to its chromatin localization and activation and that a defect in this regulation may increase genome instability and promote tumorigenesis.
Critical role of parathyroid hormone (PTH) receptor-1 phosphorylation in regulating acute responses to PTH
Authors: Maeda Akira , Okazaki Makoto , Baron David M. , Dean Thomas , Khatri Ashok , Mahon Mathew , Segawa Hiroko , Abou-Samra Abdul B. , Jüppner Harald , Bloch Kenneth D. , Potts John T. , Gardella Thomas J.
Published: March 2013

Agonist-induced phosphorylation of the parathyroid hormone (PTH) receptor 1 (PTHR1) regulates receptor signaling in vitro, but the role of this phosphorylation in vivo is uncertain. We investigated this role by injecting “knock-in” mice expressing a phosphorylation-deficient (PD) PTHR1 with PTH ligands and assessing acute biologic responses. Following injection with PTH (1–34), or with a unique, long-acting PTH analog, PD mice, compared with WT mice, exhibited enhanced increases in cAMP levels in the blood, as well as enhanced cAMP production and gene expression responses in bone and kidney tissue. Surprisingly, however, the hallmark hypercalcemic and hypophosphatemic responses were markedly absent in the PD mice, such that paradoxical hypocalcemic and hyperphosphatemic responses were observed, quite strikingly with the long-acting PTH analog. Spot urine analyses revealed a marked defect in the capacity of the PD mice to excrete phosphate, as well as cAMP, into the urine in response to PTH injection. This defect in renal excretion was associated with a severe, PTH-induced impairment in glomerular filtration, as assessed by the rate of FITC-inulin clearance from the blood, which, in turn, was explainable by an overly exuberant systemic hypotensive response. The overall findings demonstrate the importance in vivo of PTH-induced phosphorylation of the PTHR1 in regulating acute ligand responses, and they serve to focus attention on mechanisms that underlie the acute calcemic response to PTH and factors, such as blood phosphate levels, that influence it.
Boron neutron capture therapy demonstrated in mice bearing EMT6 tumors following selective delivery of boron by rationally designed liposomes
Authors: Kueffer Peter J. , Maitz Charles A. , Khan Aslam A. , Schuster Seth A. , Shlyakhtina Natalia I. , Jalisatgi Satish S. , Brockman John D. , Nigg David W. , Hawthorne M. Frederick
Published: March 2013

The application of boron neutron capture therapy (BNCT) following liposomal delivery of a
10
B-enriched polyhedral borane and a carborane against mouse mammary adenocarcinoma solid tumors was investigated. Unilamellar liposomes with a mean diameter of 134 nm or less, composed of an equimolar mixture of cholesterol and 1,2-distearoyl-
sn
-glycero-3-phosphocholine and incorporating Na
3
[1-(2′-B
10
H
9
)-2-NH
3
B
10
H
8
] in the aqueous interior and K[
nido
-7-CH
3
(CH
2
)
15
-7,8-C
2
B
9
H
11
] in the bilayer, were injected into the tail veins of female BALB/c mice bearing right flank EMT6 tumors. Biodistribution studies indicated that two identical injections given 24 h apart resulted in tumor boron levels exceeding 67 µg/g tumor at 54 h—with tumor/blood boron ratios being greatest at 96 h (5.68:1; 43 µg boron/g tumor)—following the initial injection. For BNCT experiments, tumor-bearing mice were irradiated 54 h after the initial injection for 30 min with thermal neutrons, resulting in a total fluence of 1.6 × 10
12
neutrons per cm
2
(±7%). Significant suppression of tumor growth was observed in mice given BNCT vs. control mice (only 424% increase in tumor volume at 14 d post irradiation vs. 1551% in untreated controls). In a separate experiment in which mice were given a second injection/irradiation treatment 7 d after the first, the tumor growth was vastly diminished (186% tumor volume increase at 14 d). A similar response was obtained for mice irradiated for 60 min (169% increase at 14 d), suggesting that neutron fluence was the limiting factor controlling BNCT efficacy in this study.
Superior reaction to changing directions for skilled basketball defenders but not linked with specialised anticipation
Authors: Fujii Keisuke , Shinya Masahiro , Yamashita Daichi , Oda Shingo , Kouzaki Motoki
Published: March 2013

The purpose of the present study was to examine the timing for the detection of relevant information in the final running direction of attackers' cutting manoeuvres. Skilled basketball players and novices performed sidestep and reach tasks in response to a ready‐go choice stimuli using light‐emitting diode (LED) task and video stimuli (video task) wherein skilled ball players executed cutting manoeuvres. The time at which the defenders first obtained relevant visual information was estimated by subtracting the visuo‐motor processing time, acquired from the reaction time in the LED task, from the reaction time in the video task. Skilled basketball players reacted to and reached towards the target faster than novices, whereas the estimated video cue timings for the skilled players were not different from those for the novices. The results suggest that the anticipation of attacker's direction in this task would be a general visuo‐motor skill, even without previous specialised perceptual training. Combined with the results from the reaction performance in the video task, we conclude that novices are afforded shorter times and more uncertain information before their stepping when they are in a one‐on‐one ballgame defensive scenario because their sidestepping takes a relatively long time.
Non-interlaced solutions of 2-dimensional systems of linear ordinary differential equations
Authors: Le Gal O. , Sanz F. , Speissegger P.
Published: March 2013

We consider a

2
2

-dimensional system of linear ordinary differential equations whose coefficients are definable in an o-minimal

structure

R

\mathcal {R}

. We prove that either every pair of solutions at 0 of the system is interlaced or the expansion of

R

\mathcal {R}

by all solutions at 0 of the system is o-minimal. We also show that if the coefficients of the system have a Taylor development of sufficiently large finite order, then the question of which of the two cases holds can be effectively determined in terms of the coefficients of this Taylor development.
A stalled retrotranslocation complex reveals physical linkage between substrate recognition and proteasomal degradation during ER-associated degradation
Authors: Nakatsukasa Kunio , Brodsky Jeffrey L. , Kamura Takumi
Published: March 2013

During endoplasmic reticulum–associated degradation (ERAD), misfolded lumenal and membrane proteins in the ER are recognized by the transmembrane Hrd1 ubiquitin ligase complex and retrotranslocated to the cytosol for ubiquitination and degradation. Although substrates are believed to be delivered to the proteasome only after the ATPase Cdc48p/p97 acts, there is limited knowledge about how the Hrd1 complex coordinates with Cdc48p/p97 and the proteasome to orchestrate substrate recognition and degradation. Here we provide evidence that inactivation of Cdc48p/p97 stalls retrotranslocation and triggers formation of a complex that contains the 26S proteasome, Cdc48p/p97, ubiquitinated substrates, select components of the Hrd1 complex, and the lumenal recognition factor, Yos9p. We propose that the actions of Cdc48p/p97 and the proteasome are tightly coupled during ERAD. Our data also support a model in which the Hrd1 complex links substrate recognition and degradation on opposite sides of the ER membrane.
Angiotensin-converting enzyme 2 activity in patients with chronic kidney disease
Authors: Roberts Matthew A. , Velkoska Elena , Ierino Francesco L. , Burrell Louise M.
Published: March 2013

Background

Angiotensin-converting enzyme 2 (ACE2) is a novel regulator of the renin–angiotensin system that counteracts the adverse effects of angiotensin II. In heart failure patients, elevated plasma ACE2 activity predicted adverse events and greater myocardial dysfunction. We aimed to describe plasma ACE2 activity and its clinical associations in patients with kidney disease.

Methods

Patients recruited from a single centre comprised of chronic kidney disease Stage III/IV (CKD), haemodialysis patients and kidney transplant recipients (KTRs). Plasma ACE2 enzyme activity was measured using a fluorescent substrate assay in plasma, collected at baseline and stored at −80°C. Linear regression was performed in both males and females separately to determine the covariates associated with log-transformed ACE2.

Results

The median (interquartile range) plasma ACE2 activity in pmol/mL/min was 15.9 (8.4–26.1) in CKD (n = 59), 9.2 (3.9–18.2) in haemodialysis (n = 100) and 13.1 (5.7–21.9) in KTR (n = 80; P < 0.01). In male haemodialysis patients, ACE2 activity was 12.1 (6.8–19.6) compared with 4.4 (2.5–10.3) in females (P < 0.01). Log-transformed ACE2 plasma activity was associated with post-haemodialysis systolic blood pressure in females [β-coefficient 0.04, 95% confidence interval (95% CI) 0.01–0.06, P = 0.006]. In males, log-transformed ACE2 plasma activity was associated with B-type natriuretic peptide (β-coefficient 0.39, 95% CI 0.19–0.60, P < 0.001). Plasma ACE2 activity was not associated with mortality.

Conclusions

Plasma ACE2 activity is reduced in haemodialysis patients compared with CKD patients, and in female haemodialysis patients compared with male. The different associations of plasma ACE2 activity between male and female haemodialysis patients indicate that the role of ACE2 in cardiovascular disease may differ by gender.
Bombyx mori nucleopolyhedrovirus BmP95 plays an essential role in budded virus production and nucleocapsid assembly
Authors: Xiang Xingwei , Shen Yunwang , Yang Rui , Chen Lin , Hu Xiaolong , Wu Xiaofeng
Published: March 2013

Bombyx mori nucleopolyhedrovirus (BmNPV) BmP95 is a highly conserved gene that is found in all of the baculovirus genomes sequenced to date and is also found in nudiviruses. To investigate the role of BmP95 in virus infection in vitro, a BmP95 deletion virus (vBmP95-De) was generated by homologous recombination in Escherichia coli. Fluorescence and light microscopy and titration analysis indicated that the BmP95 deletion bacmid led to a defect in production of infectious budded virus (BV). However, deletion of BmP95 did not affect viral DNA replication. Electron microscopy showed that masses of aberrant tubular structures were present in cells transfected with the BmP95 deletion bacmid, indicating that deletion of BmP95 affected assembly of the nucleocapsid. This defect could be rescued by insertion of full-length BmP95 into the polyhedrin locus of the BmP95-knockout bacmid but not the N-terminal domain of BmP95. Together, these results showed that full-length BmP95 is essential for BV production and is required for nucleocapsid assembly.
A Genetic and Metabolic Analysis Revealed that Cotton Fiber Cell Development Was Retarded by Flavonoid Naringenin
Authors: Tan Jiafu , Tu Lili , Deng Fenglin , Hu Haiyan , Nie Yichun , Zhang Xianlong
Published: March 2013

The cotton (Gossypium spp.) fiber is a unique elongated cell that is useful for investigating cell differentiation. Previous studies have demonstrated the importance of factors such as sugar metabolism, the cytoskeleton, and hormones, which are commonly known to be involved in plant cell development, while the secondary metabolites have been less regarded. By mining public data and comparing analyses of fiber from two cotton species (Gossypium hirsutum and Gossypium barbadense), we found that the flavonoid metabolism is active in early fiber cell development. Different flavonoids exhibited distinct effects on fiber development during ovule culture; among them, naringenin (NAR) could significantly retard fiber development. NAR is a substrate of flavanone 3-hydroxylase (F3H), and silencing the F3H gene significantly increased the NAR content of fiber cells. Fiber development was suppressed following F3H silencing, but the overexpression of F3H caused no obvious effects. Significant retardation of fiber growth was observed after the introduction of the F3H-RNA interference segment into the high-flavonoid brown fiber G. hirsutum T586 line by cross. A greater accumulation of NAR as well as much shorter fibers were also observed in the BC1 generation plants. These results suggest that NAR is negatively associated with fiber development and that the metabolism mediated by F3H is important in fiber development, thus highlighting that flavonoid metabolism represents a novel pathway with the potential for cotton fiber improvement.
Crystallization and preliminary X-ray crystallographic studies of the coiled-coil domain of PIST
Authors: Shin Young-Cheul , Seo Eun Kyoung , Jeon Ju-Hong , Park Hyun Ho
Published: March 2013

PIST [PDZ (PSD-95, Discs-large and ZO-1) protein interacting specifically with TC10] functions as a regulator of membrane trafficking with Rab6A. Recently, the involvement of the fusion of PIST with ROS1 in cancer development has been identified. In this study, the coiled-coil domain of PIST, which is the domain responsible for interaction with Rab6A and fusion with ROS1, corresponding to amino acids 29–133, was overexpressed inEscherichia coliusing engineered C-terminal His tags. The coiled-coil domain of PIST was then purified to homogeneity and crystallized at 293 K. Finally, X-ray diffraction data were collected to a resolution of 4.0 Å from a crystal belonging to the hexagonal space groupP6222 orP6422, with unit-cell parametersa=b= 85.19,c= 240.09 Å, γ = 120.00°.
Purification, crystallization and preliminary X-ray diffraction analysis of effector protein MoHrip2 fromMagnaporthe oryzae
Authors: Liu Mengjie , Liu Xinqi , Zeng Hongmei , Qiu Dewen
Published: March 2013

MoHrip2, a novel effector protein from the pathogenic fungusMagnaporthe oryzae, was purified and crystallized using the sitting-drop vapour-diffusion method. Native crystals and selenomethionine-labelled crystals were obtained using 2.2 Mammonium sulfate as a precipitant. A native data set was collected to 2.0 Å resolution at 100 K using an in-house X-ray source and a selenomethionine-labelled data set containing anomalous signal was collected to 1.8 Å resolution at 100 K using a synchrotron source. Based on the anomalous signal generated from the Se atom, the MoHrip2 structure was successfully solved using the single-wavelength anomalous dispersion (SAD) method.
Structural‐aeroelastic finite element modeling for advanced‐geometry rotor blades
Authors: Piccione Emanuele , Bernardini Giovanni , Gennaretti Massimo
Published: March 2013

Purpose

The purpose of this paper is to present the development and application of a numerical formulation for the structural dynamics and aeroelastic analysis of new generation helicopter and tiltrotor rotor blades. These are characterized by a curvilinear elastic axis, typically with the presence of tip sweep and anhedral angles.

Design/methodology/approach

The structural dynamics model implemented is based on nonlinear, flap‐lag‐torsion, rotating beam equations that are valid for slender, homogeneous, isotropic, non‐uniform, twisted blades undergoing moderate displacements. A second‐order approximation scheme for strain‐displacement is adopted. Aerodynamic contributions for aeroelastic applications are derived from sectional theories, with inclusion of wake inflow models to take into account three‐dimensional effects. The numerical integration is obtained through implementation within the COMSOL Multiphysics Finite‐Element‐Method (FEM) software code, considering the elastic axis of arbitrary curvilinear shape.

Findings

The computational tool developed is validated by comparisons with results available in the literature. These demonstrate the capability of the tool to accurately predict structural dynamics and aeroelastic behavior of curved‐axis rotor blades. In particular, the influence of sweep and anhedral angles at the blade tip is successfully captured.

Research limitations/implications

The numerical tool developed is limited to the analysis of isotropic blades, with a simple sectional aerodynamic modeling for aeroelastic applications. However, the flexibility of the process through which the proposed tool has been developed is such that a moderate effort is required for its extension to composite blades and more accurate aerodynamic loads predictions.

Practical implications

The proposed computational solver is a reliable tool for preliminary design and optimal design processes of helicopter and tiltrotor rotor blades.

Originality/value

Computational tools for rotors with advanced‐geometry blades are not commonly available. Therefore, the presentation of a successful way to implement structural dynamics/aeroelastic mathematical formulations for rotor blades with curvilinear elastic axis in highly flexible, multiphysics, FEM‐based, commercial software may be of interest for designers and researchers.
Evaluation of synthetic jet actuators design performance
Authors: Dahalan Nizam , Mansor Shuhaimi , Haniff Shaharudin Muhammad , Ali Airi
Published: March 2013

Purpose

The purpose of this paper is to evaluate the synthetic jet actuator design's performance based on piezoelectric diaphragms that can be appropriately used for flow separation control.

Design/methodology/approach

Design the synthetic jet actuators by means of estimating the several parameters and non‐dimensional parameters. Understanding the relationship and coupling effects of these parameters on the actuator to produce exit air jet required. Experiments were conducted to measure the exit air jet velocity using a hot‐wire anemometry and determine the good operational frequencies and voltages of the actuators for different cavity volume.

Findings

The performance of synthetic jet actuator is not consistent to a particular given frequency and it depends on design configurations. Each actuator will give a very good speed for a certain frequency. The results show that the exit air jet velocity increases would be better if the cavity volume is reduced and if the input voltage is increased to certain limits.

Research limitations/implications

The limit of input voltage for the actuators that can be achieved for good jet speed is 2V of about 205V output voltage for each frequency. The jet speed obtained is sufficient enough to control the separation for an aircraft which has a small wing chord and low speed. Therefore, more studies are needed to optimize the sizes of an orifice and cavity, and the selection of piezoelectric diaphragm.

Practical implications

The study helps in establishing a flow control device for controlling flow separation, especially on airfoils.

Originality/value

Design the synthetic jet actuators based on piezoelectric diaphragm for applications of flow separation control.
Investigation on instable current issue of scanning mechanism
Authors: Yu Shuang , Miao Jun , Wang Hua , Qian Zhiyuan
Published: March 2013

Purpose

The purpose of this paper is to find the root cause of the current issue for a scan drive mechanism which is used to drive and to control the Microwave Radiometer Imager (MWRI) equipment of the FY‐3 meteorological satellite in China.

Design/methodology/approach

In order to find the root cause of the irregularly unstable motor current, some possible reasons for this anomaly, including satellite dynamic, telemetry, electronics and mechanism system, are investigated. The root cause is focused on the mechanism that is increasing friction caused by limitation rollers striking the rotating part from time to time, which has been verified by simulation and test.

Findings

Findings gained from the simulations and tests results were: for a rotational space mechanism with high velocity accuracy requirement, if the moment of inertial (MOI) of the load is quite large, the balance is the key factor to the equipment performance. Moreover, thermal gradient and temperature difference are also important factors, especially to the space mechanism with large dimensions. Even a very small thermal deformation can lead to quite a number of unexpected results.

Practical implications

The better performance of the next optimized MWRI equipment in orbit showed that the performed measures are very effective and useful. The experience gained in settling this issue can be used for the design of a space scanning mechanism with high rotating speed and high accuracy.

Originality/value

The paper is an original work for the authors. The issue has not been found in the related literatures. It is based on research work on an engineering problem of unstable current issue, which is significant to the MWRI payload of the FY‐3 satellite.
A nonlinear stability analysis of elastic flight vehicle
Authors: Shamaghdari Saeed , Nikravesh S.K.Y.
Published: March 2013

Purpose

The purpose of this paper is to present a nonlinear model along with stability analysis of a flexible supersonic flight vehicle system.

Design/methodology/approach

The mathematical state space nonlinear model of the system is derived using Lagrangian approach such that the applied force, moment, and generalized force are all assumed to be nonlinear functions of the system states. The condition under which the system would be unstable is derived and when the system is stable, the region of attraction of the system equilibrium state is determined using the Lyapunov theory and sum of squares optimization method. The method is applied to a slender flexible body vehicle, which is referenced by the other researchers in the literature.

Findings

It is demonstrated that neglecting the nonlinearity in external force, moment and generalized force, as it was assumed by other researchers, can cause significant variations in stability conditions. Moreover, when the system is stable, it is shown analytically here that a reduction in dynamic pressure can make a larger region of attraction, and thus instability will occur in a larger angle of attack, greater angular velocity and elastic displacement.

Practical implications

In order to carefully study the behavior of aeroelastic flight vehicle, a nonlinear model and analysis is definitely necessary. Moreover, for the design of the airframe and/or control purposes, it is essential to investigate region of attraction of equilibrium state of the stable flight vehicle.

Originality/value

Current stability analysis methods for nonlinear elastic flight vehicles are unable to determine the state space region where the system is stable. Nonlinear modeling affects the determination of the stability region and instability condition. This paper presents a new approach to stability analysis of the nonlinear flexible flight vehicle. By determining the region of attraction when the system is stable, it is demonstrated analytically, in this research, that decreasing the dynamic pressure can produce larger region of attraction.
Robust flutter analysis and control of a wing
Authors: Fatehi Mahdi , Moghaddam Majid , Rahim Mohammad
Published: March 2013

Purpose

The purpose of this paper is to present a novel approach in aeroservoelastic analysis and robust control of a wing section with two control surfaces in leading‐edge and trailing‐edge. The method demonstrates how the number of model uncertainties can affect the flutter margin.

Design/methodology/approach

The proposed method effectively incorporates the structural model of a wing section with two degrees of freedom of pitch and plunge with two control surfaces on trailing and leading edges. A quasi‐steady aerodynamics assumption is made for the aerodynamic modeling. Basically, perturbations are considered for the dynamic pressure models and uncertainty parameters are associated with structural stiffness and structural damping and are accounted for in the model by a Linear Fractional Transformation (LFT) model. The control commands are applied to a first and second order electro‐mechanical actuator.

Findings

Dynamic performance of aeroelastic/aeroservoelastic system including time responses, system modal specifications, critical flutter speeds, and stability margins are extracted and compared with each other. Simulation results are validated through experiments and are compared to other existing methods available to the authors. Results of simulations with four structural uncertainties and first order controllers have a good agreement with experimental test results. Furthermore, it is shown that by using a high gain second order controller, the aeroservoelastic (ASE) system does not have any coupling nature in frequency response.

Originality/value

In this study, modeling, simulation, and robust control of a wing section have been investigated utilizing the μ‐Analysis method and the wing flutter phenomenon is predicted in the presence of multiple uncertainties. The proposed approach is an advanced method compared to conventional flutter analysis methods (such as V‐g or p‐k) for calculating stability margin of aeroelastic/aeroservoelastic systems.
Gravity gradient torque of spacecraft orbiting asteroids
Authors: Wang Yue , Xu Shijie
Published: March 2013

Purpose

The purpose of this paper is to present a full fourth‐order model of the gravity gradient torque of spacecraft around asteroids by taking into consideration of the inertia integrals of the spacecraft up to the fourth order, which is an improvement of the previous fourth‐order model of the gravity gradient torque.

Design/methodology/approach

The fourth‐order gravitational potential of the spacecraft is derived based on Taylor expansion. Then the expression of the gravity gradient torque in terms of gravitational potential derivatives is derived. By using the formulation of the gravitational potential, explicit formulations of the full fourth‐order gravity gradient torque are obtained. Then a numerical simulation is carried out to verify the model.

Findings

It is found that the model is more sound and precise than the previous fourth‐order model due to the consideration of higher‐order inertia integrals of the spacecraft. Numerical simulation results show that the motion of the previous fourth‐order model is quite different from the exact motion, while the full fourth‐order model fits the exact motion very well. The full fourth‐order model is precise enough for high‐precision attitude dynamics and control around asteroids.

Practical implications

This high‐precision model is of importance for the future asteroids missions for scientific explorations and near‐Earth objects (NEOs) mitigation.

Originality/value

In comparison with previous models, a gravity gradient torque model around asteroids that is more sound and precise is established. This model is valuable for high‐precision attitude dynamics and control around asteroids.
A directional control system for UCAV automatic takeoff roll
Authors: Zhang Yunpeng , Duan Haibin
Published: March 2013

Purpose

The purpose of this paper is to develop a directional and roll control system for unmanned combat air vehicle (UCAV) automatic takeoff roll, with the objective of keeping the UCAV along the runway centerline and keeping the wings level, especially when there is a crosswind.

Design/methodology/approach

The nonlinear model of the UCAV during takeoff roll is established. The model is linearized about the lateral‐directional equilibrium point at different forward speeds. The approximate directional model and roll model are extracted using time‐scale decomposition technique. Then the directional control law and roll control law are developed using gain scheduling approach. Nose wheel steering, differential brake and rudder are used as the primary directional control device at low, medium and high speeds, respectively, according to both the qualitative and quantitative analysis of their control effectiveness at different speeds. A priority matrix is developed to determine the secondary control device which is used if the primary control device fails, thus the directional control system can have a certain degree of fault tolerance.

Findings

This work developed the directional control law and roll control law by using gain scheduling approach. Experimental results verified that the developed directional and roll control system has high robustness and satisfactory fault tolerance: it can guarantee a safe takeoff under a 50 ft/sec crosswind, even if one directional control device fails, which satisfies the relevant criteria in MIL‐HDBK‐1797.

Practical implications

The directional and roll control system developed can be easily applied to practice and can steer the UCAV during takeoff roll safely, which will considerably increase the autonomy of the UCAV.

Originality/value

The paper shows how time‐scale decomposition technique is employed to extract the approximate directional model and roll model, which simplifies model analysis and control law design. A fault‐tolerant directional control system is designed to improve safety during takeoff.
Combined fatigue experiments on full scale turbine components
Authors: Hu Dianyin , Wang Rongqiao
Published: March 2013

Purpose

The purpose of this paper is to perform experiments on a full scale turbine blade attached to a part of actual turbine disc at elevated temperature, which can accurately predict the life of a fir‐tree contact under high cycle fatigue (HCF)/low cycle fatigue (LCF) combined loading. Moreover, the effect of shot‐peening on the fatigue lives of the turbine attachments is investigated experimentally by comparing those of unpeened ones.

Design/methodology/approach

An experimental system for a full scale turbine blade attached to a part of actual turbine disc at elevated temperature is established in this paper, with a new HCF/LCF combined loading scheme and a design of blade clamp. The new combined fatigue loading method achieves a noninterfering treatment of the high cycle and low cycle loading by placing low cycle loading exerting point to the back of the mortise. Then fatigue tests were performed on six used turbine components to investigate the effect of shot‐peening on fatigue life compared with the unpeened ones.

Findings

This test system ingeniously achieves HCF/LCF combined loading of the full scale turbine component, and a special design of the blade clamp successfully simulates the stress field of the turbine blade. Experimental life data show that the shot‐peening process greatly improves the used turbine fir‐tree attachment's life.

Practical implications

The present study provides an experimental method to simulate HCF/LCF combined loading of a full scale fir‐tree turbine attachment at elevated temperature at laboratory.

Originality/value

Compared with the unpeened turbine components, the fatigue lives of the shot‐peened ones are increased greatly. Mean life of the shot‐peened turbine attachment is 5.23 times longer than that of the unpeened.
Aircraft flutter prediction using experimental modal parameters
Authors: Pankaj Achuthan C. , Shanthini G. , Shivaprasad M.V. , Manjuprasad M.
Published: March 2013

Purpose

Traditional dynamic and flutter analysis demands a detailed finite element model of the aircraft in terms of its mass and stiffness distribution. However, in absence of these details, modal parameters obtained from experimental tests can be used to predict the flutter characteristics of an aircraft. The purpose of this paper is to develop an improved and reliable method to predict the flutter characteristics of an aircraft structure of unknown configuration under an anticipated aerodynamic loading using software such as MSC Nastran and experimental modal parameters (such as mode shapes, natural frequencies and damping) from ground vibration tests.

Design/methodology/approach

A finite element model with nodes representing the test points on the aircraft is created with appropriate boundary constraints. A direct matrix abstraction program has been written for NASTRAN software that carries out a normal modes analysis and replaces the mass normalized eigenvalues and vectors with the experimentally obtained modal parameters. The flutter analysis proceeds with the solution of the flutter equation in the flutter module of NASTRAN.

Findings

The method has been evaluated for a light composite aircraft and its results have been compared with flight flutter tests and the flutter speeds obtained from the finite element model with actual stiffness and mass distributions of the aircraft.

Research limitations/implications

The methodology developed helps in the realistic prediction of flutter characteristics of a structure with known geometric configuration and does not need material properties, mass or stiffness distributions. However, experimental modal parameters of each configuration of the aircraft are required for flutter speed estimation.

Practical implications

The proposed methodology requires experimental modal parameters of each configuration of the aircraft for flutter speed estimation.

Originality/value

The paper shows that an effective method to predict flutter characteristics using modal parameters from ground vibration tests has been developed.
Solution space research for interplanetary trajectory
Authors: Zhao Zunhui , Shang Haibin , Cui Pingyuan , Huang Xiangyu
Published: March 2013

Purpose

The purpose of this paper is to present a solution space searching method to study the initial design of interplanetary low thrust gravity assist trajectory.

Design/methodology/approach

For reducing the complexity and nonlinearity of the initial design problem, a sixth degree inverse polynomial shape based approach is brought. Then some improvements are provided for solving the parameters in the shape function and a quasi‐lambert solver is brought through the shape based method, the thrust profile can be generated under the given time of flight, boundary states including positions and velocities for low thrust phase. Combining gravity assist model, the problem is summarized and an improved pruning technique is used for searching the feasible solution space for low thrust gravity assist trajectory.

Findings

Using the solution space searching method, the feasible solution region would be generated under the given mission condition. The treatment about gravity assist demonstrates more accurate than previous method. Also another advantage is that the searching method can be used to design different types of mission trajectory, including flyby and rendezvous trajectories.

Practical implications

The method can be used as an efficient approach to search the feasible region for the complex low thrust gravity assist trajectory, and it can provide appropriate initial guesses for the low thrust gravity assist trajectory in mission design phase.

Originality/value

Feasible solution space would be obtained through the searching method. The quasi‐Lambert solver in the paper is found under the shape‐based method and relative improvement, and it shows its availability during the searching process. Through mission trajectory design, the effectiveness of the method is shown.
Auditors' moral philosophies and ethical beliefs
Authors: Kung Fan‐Hua , Li Huang Cheng
Published: March 2013

Purpose

The purpose of this paper is to investigate the influence of moral philosophy on the ethical beliefs of auditors. The paper argues that an individual's moral philosophy is the key factor in how one views ethical issues and largely determines the ethical choices one makes. The paper also seeks to discover the influence of personal values on the reasoning processes associated with ethics and to explore whether the personal value preferences of auditors, as a manifestation of their moral philosophy, influence their ethical beliefs and (presumably) their subsequent actions.

Design/methodology/approach

The authors designed a survey instrument to assess the value preferences, moral philosophies, and reactions of practicing auditors to judgment dilemmas. They then employed structural equation modeling to examine the sensitivity of auditors to the competence and integrity of clients with the aim of gaining insight into the ethical beliefs of auditors in general.

Findings

These results show that value preferences alone fail as predictors of ethical beliefs. Instead, personal values have an indirect influence on ethical beliefs via moral philosophy. Moreover, auditors strongly motivated by values based on self‐enhancement were negatively associated with idealism in ethics and positively associated with relativism. Therefore, it can be concluded that idealist auditors were more likely to condemn the actions of clients that violated moral norms, while relativist auditors were more permissive.

Originality/value

The results identify the role of moral philosophy as a mediator for the personal values and ethical beliefs of auditors, shedding light on how personal values can influence ethical sensitivity.
Design management capability and product innovation in SMEs
Authors: Fernández‐Mesa Anabel , Alegre‐Vidal Joaquín , Chiva‐Gómez Ricardo , Gutiérrez‐Gracia Antonio
Published: March 2013

Purpose

The aim of this paper is to present design management as a dynamic capability and to analyze its mediating role between organizational learning capability and product innovation performance in small and medium enterprises (SMEs).

Design/methodology/approach

Structural equation modeling is used to test the research hypotheses based on data from the Italian and Spanish ceramic tile industries. The data are derived from the responses of 182 companies (50 percent of the target population) to a questionnaire addressed to Product Development Managers and Human Resource Managers.

Findings

The results suggest that organizational learning capability enhances product innovation through the mediation of design management capability. The authors find an interesting interplay between organizational learning, design management capability and product innovation that can be very useful to better understand how to improve innovation performance. This finding shows that design management, as a dynamic capability, emerges from learning and allows the firm to adapt to environmental changes.

Originality/value

Several works have studied dynamic capabilities but without specifying the nature of these capabilities. More recent empirically‐based studies conceptualize and refer to specific dynamic capabilities. In this paper, the authors present design management as a dynamic capability. This study aims also to develop a better understanding of how organizational learning capability impacts on the product innovation performance of SMEs and how this relationship is mediated by design management capability.
Tracking politics with POWER
Authors: Moreira Silvio , Batista David S. , Carvalho Paula , Couto Francisco M. , Silva Mario J.
Published: March 2013

Purpose

POWER is an ontology of political processes and entities. It is designed for tracking politicians, political organizations and elections, both in mainstream and social media. The aim of this paper is to propose a data model to describe political agents and their relations over time.

Design/methodology/approach

The authors propose a data model to describe political agents (politicans, political instutions and political associations) and their relations over time. The model is formalized as an ontology using the RDF format and the population is performed in two steps. First, a bootstrap process loads data collected from authoritative sources. Then, the ontology is enriched with alternative media names extracted from the web.

Findings

The ontology is published as a public resource following the guidelines of linked data and semantic web standards can be accessed via SPARQL endpoint.

Originality/value

The authors have developed an ontology for the political domain tailored to aid in the tasks of named entity recognition and resolution. It represents the complexity and dynamic nature of relations between political agents (politicians, political associations and political institutions) over time.
A model of student involvement in the quality assurance system at institutional level
Authors: Elassy Noha
Published: March 2013

Purpose

This paper aims to create a theoretical model of student involvement in the institutional quality assurance process at their universities.

Design/methodology/approach

The model suggested in this paper was created and developed from a critical examination of relevant literature on stakeholder involvement in decision making and quality assurance processes, regarding different disciplines.

Findings

This paper presents a theoretical model of student involvement in the institutional quality assurance with its diminutions, categories and 20 rungs of student activities. It suggests a definition of student involvement term, regarding participating in the quality assurance process at higher education institutions. The importance of involving students in quality assurance procedures has been discussed. The paper provides some international experiences about student involvement in institutional QAP depending on the categories of student involvement activities that were suggested in the theoretical model.

Originality/value

The paper reveals a comprehensive model of student involvement that allows a full understanding of the extent and nature of the activities which higher education students undertake when they involve themselves in the quality assurance process at their institution.