bluuebunny/crossref_metadata_2025 huggingface dataset:
Pituitary adenylyl cyclase activating polypeptide inhibits gli1 gene expression and proliferation in primary medulloblastoma derived tumorsphere cultures
Authors: Cohen Joseph R , Resnick Daniel Z , Niewiadomski Pawel , Dong Hongmei , Liau Linda M , Waschek James A
Published: December 2010

Background

Hedgehog (HH) signaling is critical for the expansion of granule neuron precursors (GNPs) within the external granular layer (EGL) during cerebellar development. Aberrant HH signaling within GNPs is thought to give rise to medulloblastoma (MB) - the most commonly-observed form of malignant pediatric brain tumor. Evidence in both invertebrates and vertebrates indicates that cyclic AMP-dependent protein kinase A (PKA) antagonizes HH signalling. Receptors specific for the neuropeptide pituitary adenylyl cyclase activating polypeptide (PACAP, gene name ADCYAP1) are expressed in GNPs. PACAP has been shown to protect GNPs from apoptosisin vitro, and to interact with HH signaling to regulate GNP proliferation. PACAP/ptch1double mutant mice exhibit an increased incidence of MB compared toptch1mice, indicating that PACAP may regulate HH pathway-mediated MB pathogenesis.

Methods

Primary MB tumorsphere cultures were prepared from thirteenptch1+/-/p53+/-double mutant mice and treated with the smoothened (SMO) agonist purmorphamine, the SMO antagonist SANT-1, the neuropeptide PACAP, the PKA activator forskolin, and the PKA inhibitor H89. Gene expression ofgli1and [3H]-thymidine incorporation were assessed to determine drug effects on HH pathway activity and proliferation, respectively. PKA activity was determined in cell extracts by Western blotting using a phospho-PKA substrate antibody.

Results

Primary tumor cells cultured for 1-week under serum-free conditions grew as tumorspheres and were found to express PAC1 receptor transcripts.Gli1gene expression was significantly reduced by SANT-1, PACAP and forskolin, but was unaffected by purmorphamine. The attenuation ofgli1gene expression by PACAP was reversed by the PKA inhibitor H89, which also blocked PKA activation. Treatment of tumorsphere cultures with PACAP, forskolin, and SANT-1 for 24 or 48 hours reduced proliferation.

Conclusions

Primary tumorspheres derived fromptch1+/-/p53+/-mice exhibit constitutive HH pathway activity. PACAP antagonizes HH signalling in these cells in a manner blocked by the PKA antagonist H89. PACAP and pharmacological activation of PKA also inhibited proliferation. Our data suggests that regulation of HH signaling by PACAP/PKA signaling may provide an alternative to SMO inhibition for the treatment of MB.
Relationship between clinical signs and postmortem test status in cattle experimentally infected with the bovine spongiform encephalopathy agent
Authors: Konold Timm , Sayers A Robin , Sach Amanda , Bone Gemma E , van Winden Steven , Wells Gerald AH , Simmons Marion M , Stack Michael J , Wear Angus , Hawkins Steve AC
Published: December 2010

Background

Various clinical protocols have been developed to aid in the clinical diagnosis of classical bovine spongiform encephalopathy (BSE), which is confirmed by postmortem examinations based on vacuolation and accumulation of disease-associated prion protein (PrPd) in the brain. The present study investigated the occurrence and progression of sixty selected clinical signs and behaviour combinations in 513 experimentally exposed cattle subsequently categorised postmortem as confirmed or unconfirmed BSE cases. Appropriate undosed or saline inoculated controls were examined similarly and the data analysed to explore the possible occurrence of BSE-specific clinical expression in animals unconfirmed by postmortem examinations.

Results

Based on the display of selected behavioural, sensory and locomotor changes, 20 (67%) orally dosed and 17 (77%) intracerebrally inoculated pathologically confirmed BSE cases and 21 (13%) orally dosed and 18 (6%) intracerebrally inoculated but unconfirmed cases were considered clinical BSE suspects. None of 103 controls showed significant signs and were all negative on diagnostic postmortem examinations. Signs indicative of BSE suspects, particularly over-reactivity and ataxia, were more frequently displayed in confirmed cases with vacuolar changes in the brain. The display of several BSE-associated signs over time, including repeated startle responses and nervousness, was significantly more frequent in confirmed BSE cases compared to controls, but these two signs were also significantly more frequent in orally dosed cattle unconfirmed by postmortem examinations.

Conclusions

The findings confirm that in experimentally infected cattle clinical abnormalities indicative of BSE are accompanied by vacuolar changes and PrPd accumulation in the brainstem. The presence of more frequently expressed signs in cases with vacuolar changes is consistent with this pathology representing a more advanced stage of disease. That BSE-like signs or sign combinations occur in inoculated animals that were not confirmed as BSE cases by postmortem examinations requires further study to investigate the potential causal relationship with prion disease.
Endocrine Actions of Myostatin: Systemic Regulation of the IGF and IGF Binding Protein Axis
Authors: Williams Nolann G. , Interlichia Jillian P. , Jackson Melissa F. , Hwang David , Cohen Pinchas , Rodgers Buel D.
Published: December 2010

Myostatin’s inhibitory actions on striated muscle growth are believed to be directly mediated by locally produced myostatin and possibly by IGF binding proteins (IGFBPs). We therefore measured skeletal muscle, heart, and liver expression, in neonates and adults, and circulating levels of various IGF axis components (IGF-I, IGFBP-1 to IGFBP-3, and acid labile subunit) in wild-type and mstn−/− mice. Compared with wild type, differences in muscle expression were tissue specific, although IGF-I receptor expression was higher in all mstn−/− neonatal tissues and in adult gastrocnemius. Liver expression of several components also differed between genotype as IGF-I receptor, IGFBP-3 and IGFBP-5 expression was higher in mstn−/− neonates and IGF-I and IGFBP-3 in adults. Circulating IGF-I levels were also higher in mstn−/− adults, whereas IGFBP-1 and IGFBP-2 levels were lower. Comparing IGF-I:IGFBP molar ratios suggested that the relative IGF-binding capacity was potentially lower in mstn−/− mice, and thus, total and “free” IGF-I levels may be elevated. This in turn may increase negative feedback control on GH, because mstn−/− liver weights were lower. Bone growth was similar in both genotypes, suggesting that changes in circulating IGF-I may be more important to muscle, whose mass is enhanced in mstn−/− mice, than to bone. Myostatin receptors, but not myostatin itself, are expressed in the liver. Changes in hepatic production of circulating IGF axis components could therefore result from the loss of endocrine myostatin. Thus, myostatin may inhibit striated muscle growth directly at the cellular level and indirectly through systemic effects on the IGF axis.
Advanced Pubertal Growth Spurt in Subjects Born Preterm: The Helsinki Study of Very Low Birth Weight Adults
Authors: Wehkalampi Karoliina , Hovi Petteri , Dunkel Leo , Strang-Karlsson Sonja , Järvenpää Anna-Liisa , Eriksson Johan G. , Andersson Sture , Kajantie Eero
Published: December 2010

abstract

Context:

Among people born at term, low birth weight is associated with early puberty. Early maturation may be on the pathway linking low birth weight with cardiovascular disease and type 2 diabetes. Subjects born preterm with very low birth weight (VLBW; <1500 g) have as adults increased risk factors for cardiovascular disease. Little is known about their pubertal timing.

Objective:

The objective of the investigation was to study the timing of pubertal growth in subjects born preterm with VLBW as compared with controls.

Design, Setting, and Participants:

A follow-up study of subjects born preterm including 188 VLBW and 190 term-born control subjects. Growth data were available for 128 VLBW and 147 control subjects, of whom we excluded 15 and 1, respectively, because of neurological impairment.

Main Outcome Measure:

Timing of pubertal growth spurt was estimated by assessing the ages, corrected for gestational age at birth, at acceleration (take-off) and peak height velocity of pubertal growth, and age at attaining adult height.

Results:

All components of pubertal growth occurred earlier in VLBW subjects than in controls. Age at take-off was 0.8 yr earlier [95% confidence interval (CI) 0.4–1.3] in VLBW subjects born appropriate and 0.9 yr earlier (95% CI 0.4–1.5) in those born small for gestational age. VLBW subjects were more likely to have a pubertal growth spurt that was at least 2 yr earlier than population average [odds ratio 3.8 (95% CI: 1.5–9.6)].

Conclusions:

Prematurity per se is associated with advanced pubertal growth. Advanced puberty may be among the factors mediating adult metabolic outcomes in subjects born preterm with VLBW.
Suppression of Insulin-Like3 Receptor Reveals the Role of β-Catenin and Notch Signaling in Gubernaculum Development
Authors: Kaftanovskaya Elena M. , Feng Shu , Huang Zaohua , Tan Yingchun , Barbara Agustin M. , Kaur Sukhjinder , Truong Anne , Gorlov Ivan P. , Agoulnik Alexander I.
Published: December 2010

During male development, the testes move from a high intraabdominal position and descend into the scrotum. The gubernaculum, an inguinoscrotal ligament connecting the testis to the lower abdomen, is believed to play a critical role in this process. The first stage of testicular descent is controlled by insulin like3 hormone (INSL3), produced in testicular Leydig cells. Deletion of Insl3 or its receptor, Rxfp2, in mice causes cryptorchidism. We produced Cre/loxP regulated shRNA transgenic mice targeting RXFP2 expression. We have shown that the transgene was able to reduce Rxfp2 gene expression and thus behaved as a hypomorphic allele of Rxfp2. Variable degrees of uni- and bilateral cryptorchidism was detected in males with the activated shRNA transgene on an Rxfp2+/− background. Conditional suppression of Rxfp2 in the gubernaculum led to cryptorchidism. Gene expression analysis of a mutant cremasteric sac using Illumina microarrays indicated abnormal expression of a significant number of genes in Wnt/β-catenin and Notch pathways. We have demonstrated profound changes in the expression pattern of β-catenin, Notch1, desmin, and androgen receptor (AR), in Rxfp2−/− male embryos, indicating the role of INSL3 in proliferation, differentiation, and survival of specific cellular components of the gubernaculum. We have shown that INSL3/RXFP2 signaling is essential for myogenic differentiation and maintenance of AR-positive cells in the gubernaculum. Males with the deletion of β-catenin or Notch1 in the gubernacular ligament demonstrated abnormal development. Our data indicates that β-catenin and Notch pathways are potential targets of INSL3 signaling during gubernacular development.
Protein O-mannosyltransferases participate in ER protein quality control
Authors: Goder Veit , Melero Alejandro
Published: December 2010

In eukaryotic cells, proteins enter the secretory pathway at the endoplasmic reticulum (ER) as linear polypeptides and fold after translocation across or insertion into the membrane. If correct folding fails, many proteins are O-mannosylated inside the ER by an O-mannosyltransferase, the Pmt1p–Pmt2p complex. The consequences of this modification are controversial and the cellular role of the Pmt1p–Pmt2p complex in this respect is unclear. Here, we have identified the binding partners of yeast Pmt1p and Pmt2p. These include ER chaperones involved in oxidative protein folding; the Hrd1p complex, which is involved in ER-associated protein degradation (ERAD); and the p24 protein complex involved in ER export. The results suggest that the Pmt1p–Pmt2p complex participates in these processes. We tested this assumption in a functional assay and found that whereas the Pmt1p–Pmt2p complex promotes fast ER export of the GPI-anchored protein Gas1p, it retains the misfolded version Gas1*p and targets it to the Hrd1p complex for subsequent degradation. Our results reveal previously unknown cellular roles of the Pmt1p–Pmt2p complex in connection with the ERAD machinery and show its participation in ER protein quality control.
Serum- and glucocorticoid-inducible kinase 1 (SGK1) controls Notch1 signaling by downregulation of protein stability through Fbw7 ubiquitin ligase
Authors: Mo Jung-Soon , Ann Eun-Jung , Yoon Ji-Hye , Jung Jane , Choi Yun-Hee , Kim Hwa-Young , Ahn Ji-Seon , Kim Su-Man , Kim Mi-Yeon , Hong Ji-Ae , Seo Mi-Sun , Lang Florian , Choi Eui-Ju , Park Hee-Sae
Published: December 2010

Notch is a transmembrane protein that acts as a transcriptional factor in the Notch signaling pathway for cell survival, cell death and cell differentiation. Notch1 and Fbw7 mutations both lead the activation of the Notch1 pathway and are found in the majority of patients with the leukemia T-ALL. However, little is known about the mechanisms and regulators that are responsible for attenuating the Notch signaling pathway through Fbw7. Here, we report that the serum- and glucocorticoid-inducible protein kinase SGK1 remarkably reduced the protein stability of the active form of Notch1 through Fbw7. The protein level and transcriptional activity of the Notch1 intracellular domain (Notch1-IC) were higher in SGK1-deficient cells than in SGK1 wild-type cells. Notch1-IC was able to form a trimeric complex with Fbw7 and SGK1, thereby SGK1 enhanced the protein degradation of Notch1-IC via a Fbw7-dependent proteasomal pathway. Furthermore, activated SGK1 phosphorylated Fbw7 at serine 227, an effect inducing Notch1-IC protein degradation and ubiquitylation. Moreover, accumulated dexamethasone-induced SGK1 facilitated the degradation of Notch1-IC through phosphorylation of Fbw7. Together our results suggest that SGK1 inhibits the Notch1 signaling pathway via phosphorylation of Fbw7.
Control of Aurora-A stability through interaction with TPX2
Authors: Giubettini Maria , Asteriti Italia A. , Scrofani Jacopo , De Luca Maria , Lindon Catherine , Lavia Patrizia , Guarguaglini Giulia
Published: December 2010

The Aurora-A kinase has well-established roles in spindle assembly and function and is frequently overexpressed in tumours. Its abundance is cell cycle regulated, with a peak in G2 and M phases, followed by regulated proteolysis at the end of mitosis. The microtubule-binding protein TPX2 plays a major role in regulating the activity and localisation of Aurora-A in mitotic cells. Here, we report a novel regulatory role of TPX2 and show that it protects Aurora-A from degradation both in interphase and in mitosis in human cells. Specifically, Aurora-A levels decrease in G2 and prometaphase cells silenced for TPX2, whereas degradation of Aurora-A is impaired in telophase cells overexpressing the Aurora-A-binding region of TPX2. The decrease in Aurora-A in TPX2-silenced prometaphases requires proteasome activity and the Cdh1 activator of the APC/C ubiquitin ligase. Reintroducing either full-length TPX2, or the Aurora-A-binding region of TPX2, but not a truncated TPX2 mutant lacking the Aurora-A-interaction domain, restores Aurora-A levels in TPX2-silenced prometaphases. The control by TPX2 of Aurora-A stability is independent of its ability to activate Aurora-A and to localise it to the spindle. These results highlight a novel regulatory level impinging on Aurora-A and provide further evidence for the central role of TPX2 in regulation of Aurora-A.
Sudden Stops, Financial Crises, and Leverage
Authors: Mendoza Enrique G
Published: December 2010

Financial crashes were followed by deep recessions in the Sudden Stops of emerging economies. An equilibrium business cycle model with a collateral constraint explains this phenomenon as a result of the amplification and asymmetry that the constraint induces in the responses of macro-aggregates to shocks. Leverage rises during expansions, and when it rises enough it triggers the constraint, causing a Fisherian deflation that reduces credit and the price and quantity of collateral assets. Output and factor allocations fall because access to working capital financing is also reduced. Precautionary saving makes Sudden Stops low probability events nested within normal cycles, as observed in the data. (JEL E21, E23, E32, E44, G01, O11, O16)
An Exploration of Technology Diffusion
Authors: Comin Diego , Hobijn Bart
Published: December 2010

We develop a model that, at the aggregate level, is similar to the one-sector neoclassical growth model; at the disaggregate level, it has implications for the path of observable measures of technology adoption. We estimate it using data on the diffusion of 15 technologies in 166 countries over the last two centuries. Our results reveal that, on average, countries have adopted technologies 45 years after their invention. There is substantial variation across technologies and countries. Newer technologies have been adopted faster than old ones. The cross-country variation in the adoption of technologies accounts for at least 25 percent of per capita income differences. (JEL O33, O41, O47)
Institutions and Behavior: Experimental Evidence on the Effects of Democracy
Authors: Bó Pedro Dal , Foster Andrew , Putterman Louis
Published: December 2010

A novel experiment is used to show that the effect of a policy on the level of cooperation is greater when it is chosen democratically by the subjects than when it is exogenously imposed. In contrast to the previous literature, our experimental design allows us to control for selection effects (e.g., those who choose the policy may be affected differently by it). Our finding implies that democratic institutions may affect behavior directly in addition to having effects through the choice of policies. Our findings have implications for the generalizability of the results of randomized policy interventions. (JEL C91, D02, D12, D72)
Exploiting Naïvete about Self-Control in the Credit Market
Authors: Heidhues Paul , Kőszegi Botond
Published: December 2010

We analyze contract choices, loan-repayment behavior, and welfare in a model of a competitive credit market when borrowers have a taste for immediate gratification. Consistent with many credit cards and subprime mortgages, for most types of nonsophisticated borrowers the baseline repayment terms are cheap, but they are also inefficiently front loaded and delays require paying large penalties. Although credit is for future consumption, nonsophisticated consumers overborrow, pay the penalties, and back load repayment, suffering large welfare losses. Prohibiting large penalties for deferring small amounts of repayment—akin to recent regulations in the US credit-card and mortgage markets—can raise welfare. (JEL D14, D18, D49, D86)
Inheritance Law and Investment in Family Firms
Authors: Ellul Andrew , Pagano Marco , Panunzi Fausto
Published: December 2010

Entrepreneurs may be legally bound to bequeath a minimal stake to noncontrolling heirs. The size of this stake can reduce investment in family firms, by reducing the future income they can pledge to external financiers. Using a purpose-built indicator of the permissiveness of inheritance law and data for 10,004 firms from 38 countries in 1990–2006, we find that stricter inheritance law is associated with lower investment in family firms but does not affect investment in nonfamily firms. Moreover, as the model predicts, inheritance law affects investment only in family firms that experience a succession. (JEL G31, G32, K22, L26, O17).
Organizational Structure, Communication, and Group Ethics
Authors: Ellman Matthew , Pezanis-Christou Paul
Published: December 2010

This paper investigates experimentally how a group's structure affects its ethical behavior towards a passive outsider. We analyze one vertical and two horizontal structures (one requiring consensus, one implementing a compromise by averaging proposals). We also control for internal communication. The data support our main predictions: (1) horizontal, averaging structures are more ethical than vertical structures (where subordinates do not feel responsible) and than consensual structures (where responsibility is dynamically diffused); (2) communication makes vertical structures more ethical (subordinates with voice feel responsible); (3) with communication, vertical structures are more ethical than consensual structures (where in-group bias hurts the outsider). (JEL C92, D23, L21, M14)
Negative Marginal Tax Rates and Heterogeneity
Authors: Choné Philippe , Laroque Guy
Published: December 2010

Heterogeneity is an important determinant of the shape of optimal tax schemes. This is shown here in a model à la Mirrlees. The agents differ in their productivities and opportunity costs of work, but their labor supplies depend only on a given unidimensional combination of these two characteristics. Conditions are provided under which marginal tax rates are everywhere nonnegative. This is the case when work opportunity costs are distributed independently of income. But one can also get negative marginal tax rates, in particular at the bottom of the income distribution. A numerical illustration is given, based on UK data. (JEL H21, H24, H31, J22)
Geothermal Regime of the Bohai Offshore Area, Bohai Bay Basin, North China
Authors: Qiu Nansheng , Zuo Yinhui , Zhou Xinhuai , Li Cuicui
Published: December 2010

The Bohai Offshore Area is located in the northeastern marine area of the Bohai Bay Basin in northern China. It is one of the most productive petroleum basins in China. In this study, thermal gradient and heat flow distribution results for the Bohai Offshore Area (Bohai Subbasin) were obtained based on new oil-testing temperatures, drill-stem test temperatures (DSTs), bottom-hole temperatures (BHTs) and documented thermal conductivity data. The average geothermal gradient is 32.0±4.6°C/km for the entire offshore area. Heat flow in the Bohai Subbasin ranges from 33.5 mW/m2 to 84.0 mW/m2, with an average value of 60.8±8.7mW/m2. Thermal gradient evolutions of several sags in the Bohai Subbasin were obtained using constraints for single well modeling from vitrinite reflectance ( Ro) and apatite fissin track (AFT) data. Modeling results show that there were different thermal histories for different parts of the subbasin. Generally, the thermal gradient gradually decreased with geological evolution. The thermal gradient was 57∼53°C/km in the Paleocene epoch and 53∼43°C/km during the deposition period of the Shahejie Formation (e.g., Eocene epoch). This value slowly decreased after the Oligocene (38∼43°C/km). It was 38∼34°C/km in the Miocene, and it is 32°C/km at present-day. This thermal gradient evolution relates well to activities in the Tanlu Fault Zone and to tectonic subsidence. The first episode of the syn-rift initial subsidence of the basin shows a higher thermal gradient during the Paleocene∼Eocene epochs. The second episode of thermal subsidence corresponds to a lower thermal gradient after the Oligocene epoch. The geothermal regime of the Bohai Offshore region will provide some useful data to study regional tectonic characteristics of the basin and the evolution of hydrocarbon source rocks.
Design and Experimental Study of a Gas Hydrate Mud Cooling System
Authors: Zhao Jiangpeng , Sun Youhong , Guo Wei , Xu Huiwen , Wang Qinghua , Chen Chen , Li Guosheng , Jia Rui
Published: December 2010

Mud cooling is a key technology in gas hydrate drilling operation. GHMCS (Gas Hydrate Mud Cooling System) proposed in this paper is a set of special equipment used to cool mud. The working principle, design calculations, and basic composition of the system are introduced in this paper. Laboratory experiments were carried out on the system to test its mud cooling effects. Field experiments were also carried out on the system in three gas hydrate drilling wells located in the Muli basin of Qinghai province, China. The experiments proved that the system not only achieved the goal of the design completely, but also met the mud temperature requirement of gas hydrate drilling.
Long-Term, Low Temperature Simulation of Early Diagenetic Alterations of Organic Matter: A FTIR Study
Authors: Qin Shenjun , Wang Jinxi , Zhao Cunliang , Zhang Shouxin
Published: December 2010

Early diagenetic alterations of organic matter from conifers and algae were simulated at 80°C for more than five years. To investigate the changes of functional groups of organic matter during the simulation, the samples were analysed by Fourier Transform Infrared (FTIR) spectroscopy. The basic IR spectra characteristics of coniferous and algal organic matter were elaborated. The results indicate that only the IR absorptions from aromatic rings are different. The changes of IR spectra of simulated samples show that organic matters underwent dehydroxylation, decarboxylation or polycondensation during the simulation. Besides, the differences of IR spectra among selected samples under different conditions reveal that iron-containing environment may deplete the phenolic hydroxyls in conifer samples, and the hypersaline conditions can accelerate the degradation of asphaltenes into polar compounds both in conifers and algae samples.
Pre-Drill Overpressure Prediction in the South Caspian Basin Using Seismic Data
Authors: Shykhaliyev Yu. A. , Feyzullayev A. A. , Lerche I.
Published: December 2010

Results are presented of the first pre-drill overpressure prediction in the South Caspian basin (SCB) on the basis of seismic data. The method is based on the REZAYR software package, which operates in Microsoft Windows. The analyzed seismic time-section fragment in the SCB was initially converted to an impedance section and then to a formation velocity section. Three overpressure zones of different thicknesses and extents are established. The shallowest overpressure zone extends to depths of less than 1 km. The nature of this relatively thin zone can be associated with biochemical gas generation. The second overpressure zone covers the depth interval 1.5–3 km and is most likely the result of non-equilibrium compaction (under compaction) because of high sedimentation rates. The third overpressure zone, the longest and thickest, is observed in the 6–9 km depth interval and is most likely attributed to hydrocarbons generation. This deepest zone poses the greatest risk for drilling. The seismic method of direct overpressure prediction in the SCB is in agreement with theoretical and experimental estimates and so is recommended for use in the SCB.
Current Status and Future Prospects of Renewable Energy Use in Turkey
Authors: Kirtay Elif
Published: December 2010

This paper reviews the current status of renewable energy sources, assesses their potential to contribute to Turkey's energy demand, and examines the future prospects. Turkey is rapidly growing in terms of both its economy and its population. Turkey's vibrant economy has led to increased energy demand in recent years. The major energy demand is fulfilled from the conventional fossil energy resources like coal, petroleum and natural gas. Turkey has very limited indigenous energy resources and has to import around 73% of primary energy to meet its needs. Coal –especially lignite– is by far the most plentiful energy resource in Turkey. Turkey has great potential for developing renewable energy resources, but their contribution to country's energy demand is insignificant, less than 10%. Although the institutional framework has improved in Turkey with the new Law on Renewable Energy, it is not enough to really allow for a large scale integration of renewable energy in the country. As Turkey looks towards possible EU membership, it will need to continue utilizing renewable energy as a means to achieve sustainable economic development. New regulations in line with the EU energy regulations will increase the incentives for renewable energy projects. Total energy consumption is expected to increase more rapidly than domestic energy production through 2020. The country's energy consumption is expected to grow 170 Mtoe by the year 2015 and 222 Mtoe by 2020. Turkey plans to increase hydroelectricity, wind and geothermal energy production in the near future. The Turkish government announced a 30% objective for renewable energies by 2023 with plans to push wind energy up to 20000 MW of installations for the same year.
Detailing and Construction of the Pantadome Roof Structure for a Bullring in Xàtiva (Spain)
Authors: Lázaro Carlos , Domingo Alberto
Published: December 2010

This paper describes the detailing and construction of a roof structure for a bullring in Xátiva (Spain). The roof has been built by means of a new version of the Pantadome system. The roof dome is spherical shaped with a 42 m diameter central opening and an exterior diameter of 101,6 m. It is supported on 44 columns distributed along a 86,4 m diameter circumference. The structural system is formed by radial truss lattices pinned to the columns and to the inner ring and supported by the action of an outer tension ring, radial tension members and tension (upper chord) and compression (lower chord) in the inner ring. The structure was built near the ground and lifted by shortening 44 radial strands with jacks attached to the inner ring. Strand forces have been transferred to permanent tension members at the end of the process. The kinematics of the deployment has been analyzed. Forces in the jacks have been obtained theoretically from the kinematics and compared with the measured values. Special details, developed for the attachment of the jacks and the force transfer are described. The development of the lifting process together with the results of the geometrical survey show that the new erection system allowed the construction of the dome in a quick and safe way.
Simulation of Galloping and Wind-induced Vibration Control
Authors: Li Li , Cao Huajin , Ye Kun , Jiang Yicheng
Published: December 2010

A nonlinear finite element model of transmission tower-line coupling system including transmission tower-cable-insulator is established based on ANSYS. The restarting technology is proposed to solve the vertical, horizontal and torsional galloping of the transmission conductors and the wind-induced vibration of the transmission towers. A program is developed to simulate the wind velocity; the galloping of the transmission tower line coupling system is performed to get the amplitude of the transmissions and the internal forces of the transmission towers. The calculations are performed under the condition that four fixed schemes of lead viscoelastic dampers (LVDs) to control the transmission towers wind-induced vibration, and the schemes of the damper have been optimized.
A New Method of Nonlinear Feature Extraction for Multi-Fault Diagnosis of Rotor Systems
Authors: Li Zhixiong , Yan Xinping , Yuan Chengqing , Zhao Jiangbin , Peng Zhongxiao
Published: December 2010

Rotor systems have been extensively used in a variety of industrial applications. However an unexpected failure may cause a break down of the rotational machinery, resulting in production and significant economic losses. Efficient incipient fault diagnosis is therefore critical to the machinery normal operation. Noise and vibration analysis is popular and effective for the rotor fault diagnosis. One of the key procedures in the fault diagnosis is feature extraction and selection. Literature review indicates that only limited research considered the nonlinear property of the feature space by the use of manifold learning algorithms in the field of mechanical fault diagnosis, and nonlinear feature extraction for rotor multi-fault detection has not been studied. This paper reports a new development based on a novel supervised manifold learning algorithm (adaptive locally linear embedding) applied to nonlinear feature extraction for rotor multiple defects identification. The adaptive locally linear embedding (ALLE) combines with the adaptive nearest neighbour algorithm and supervised locally linear embedding (LLE) to provide an adaptive supervised learning. Hence, distinct nonlinear features could be extracted from high-dimensional dataset effectively. Based on ALLE, a new fault diagnosis approach has been proposed. The independent component analysis (ICA) was firstly employed to separate the faulty components of the rotor vibration from the observation data. Then wavelet transform (WT) was used to decompose the recovered signals, and statistical features of frequency bands were hence calculated. Lastly, ALLE was applied to learn the low-dimensional intrinsic structure of the original feature space. The experiments on vibration data of single and coupled rotor faults have demonstrated that sensitive fault features can be extracted efficiently after the ICA-WT-ALLE processing, and the proposed diagnostic system is effective for the multi-fault identification of the rotor system. Furthermore, the proposed method achieves higher performance in terms of the classification rate than other feature extraction methods such as principal component analysis (PCA) and locally linear embedding (LLE).
Analysis of Noise and Vibration from Permanent Magnet Synchronous Motor for NC Machine Tool Servo System
Authors: Yu Shenbo , Yu Limei
Published: December 2010

In recent years, Permanent Magnet Synchronous Motors (PMSM) are widely used as the drive unit for servo system of NC machine tool. However, the motors are required to have perfect dynamic performance. It is very important to predict the characteristic of noise and vibration which are key appraisal indexes of the design of high performance motor. With the help of advanced computer and developed algorithm method, it becomes possible to realize it. This work presents an approach to calculating the distribution of electromagnetic force density in airgap and the modal shapes of the motor using finite element method. Furthermore, the acoustic field analysis is fulfilled in order to obtain the emitted process of the noise from PMSM. The effects of changing closed slot opening pattern on radiated sound pressure level of the motor are calculated. By changing the slot opening patterns, the noise of the motor is reduced.
Study on the Acoustic Field Characters of a Flame Tube Model of An Annular Combustion Chamber
Authors: Ai Yanting , Bai Shimo , Yin Banghui , Li Songjin
Published: December 2010

Combustion chamber is a core component of the hot section parts of aero engines, since it works under high-temperature and strong-noise circumstance for a long term, its lifespan is relative low and failure rate is relative high. The vibration generated by unstable combustion in the combustion chamber is very serious and the vibration generate noise, the vibration and noise will cause acoustic fatigue damage, thus affect the lifespan of the combustion chamber. According to the requirements of the integrated program on the design of aero engine structure, the structural fatigue prediction and lifespan analysis of combustion chamber are the critical issues in engine design, especially with the advent of new concepts like high efficiency and low pollution, design of new type combustion chamber is becoming more and more important. The present paper elaborated on the basic theory of cavity acoustic mode, analyzed the characteristics of acoustic field of flame tube model of an annular combustion chamber based on the FEM and BEM, and measured the open acoustic modes of dual wall cylinder modes with the experimental approach.
Analysis on the Excited Waveforms of an Electro-Hydraulic Vibration Exciter Using a Two-Dimensional Valve
Authors: Ren Yan , Ruan Jian , Yi Ji Yan
Published: December 2010

The frequency bandwidth of the conventional electro-hydraulic vibration exciter is highly dependent on the servo valve's response speed, which is always limited to a rather narrow range. A novel scheme of electro-hydraulic vibration exciter using a two-dimensional valve (2D valve) to control a hydraulic actuator is proposed in order to extend the frequency range. In this 2D valve, the rotary and linear motions of a spool are controlled independently to produce the reciprocating motion of the piston of the cylinder. The frequency and the amplitude of the excited waveform are separately controlled by the rotary motion and the sliding motion of the spool respectively. The frequency is related to the rotary speed of the spool and the coupling pattern between the grooves on the spool and windows on the sleeve. This configuration could easily extend the frequency of the hydraulic vibration exciter by increasing the rotary speed of the spool and the number of the grooves on the spool area. Based on the work principle of the electro-hydraulic vibration system, the mathematical models are first established considering a nonlinear relation between pressure and flow. Then the analytic solution to excited waveforms is solved using the subsection integration method. And the expression equations of correlated parameters are given. Finally, real excited waveforms are obtained to validate the theoretical analysis result. The results reveal that the load of electro-hydraulic vibration exciter using a 2D valve is mainly the elastic force in low frequency section, so the ascent and descent slopes of excited waveform demonstrated somewhat asymmetrically in respect that the direction of the elastic load is changed. The extent of asymmetry depends on the 2D valve's axial opening. When it exceeds a critical value, the excited waveform tends to the saturated state because of pressure saturation. The exciter waveform is also influenced by hydraulic resonance as the input frequency approaches the hydraulic resonant frequency.
Ride Comfort Optimization and Test Research on an 8×4 Heavy Truck
Authors: Pang Hui , Li H.Y. , Fang Z.D. , Shan N.
Published: December 2010

In order to study the optimization and matching between the suspension damper and the stiffness for a multi-axle heavy truck, a set of optical design methods are proposed based on the dynamics software ADAMS for the heavy truck's suspension system. Also, a frequency-domain simulation model of the 8×4 heavy truck is established in ADAMS environment. Then, the acceleration response vibration characteristics is analyzed under the condition that the truck drives on road level B with full load, Furthermore, the optimum parameters for the suspension system are gained by using the proposed optimal method. Finally, the validity of the simulation model for the truck and the efficiency of the proposed optimal method are verified by a real vehicle test. So, the research can provide important reference values for the integrated optimization and matching design of heavy truck chassis systems.
The Modeling and Simulation Analysis of Wooden Perforated Panel Absorption Structure
Authors: Ming-hui Guo , Qing-quan Hou , Jin-man Wang , Hai-peng Yu
Published: December 2010

The study analyzed the acoustical absorption performance of wooden perforated panels with finite element analysis software—ANSYS. The research process include modeling, meshing, loads, solution and results display. Simulation results showed that software ANSYS was good at absorption performance analysis of wooden perforated panels. There are some pressure distribution zones with peak and valley alternation between speaker and the tested material of the built model. It coincides with test result of real experiment equipment. The selections of structural parameters of wooden perforated panel lead to changes for solution.
Dynamic-Based Damage Identification Using Neural Network Ensembles and Damage Index Method
Authors: Dackermann Ulrike , Li Jianchun , Samali Bijan
Published: December 2010

This paper presents a vibration-based damage identification method that utilises a “damage fingerprint” of a structure in combination with Principal Component Analysis (PCA) and neural network techniques to identify defects. The Damage Index (DI) method is used to extract unique damage patterns from a damaged beam structure with the undamaged structure as baseline. PCA is applied to reduce the effect of measurement noise and optimise neural network training. PCA-compressed DI values are, then, used as inputs for a hierarchy of neural network ensembles to estimate locations and severities of various damage cases. The developed method is verified by a laboratory structure and numerical simulations in which measurement noise is taken into account with different levels of white Gaussian noise added. The damage identification results obtained from the neural network ensembles show that the presented method is capable of overcoming problems inherent in the conventional DI method. Issues associated with field testing conditions are successfully dealt with for numerical and the experimental simulations. Moreover, it is shown that the neural network ensemble produces results that are more accurate than any of the outcomes of the individual neural networks.
Finite-Element Analysis for Fatigue Evaluation of Reinforced Concrete Bridge Deck
Authors: Kumpoopong Rajwanlop , Herabat Pannapa
Published: December 2010

This paper presents the finite-element procedure for fatigue evaluation of reinforced concrete bridge deck under the application of truck wheel load. The approach is based on the smeared crack concept with the introduction of the fatigue tests of concrete and reinforcing steel available in the literature and the Palmgren-Miner linear criterion of cumulative damage in the analysis. The models are validated with the fatigue test of 1/6.6-scale AASHTO bridge deck under the application of fixed-point repetitive loading presented in previous study. Results are in good agreement. Significant contribution of the developed approach to the fatigue evaluation of bridge deck is a series of S-N relations which can be simulated at any desired levels of damage. This permits the investigation of the deterioration of bridge deck which is appeared to be useful information for highway agencies to prolong the life of their bridge decks. S-N relations are simulated at crack areas of 10%, 20%, 30%, and 40% of the bottom surface area of the deck slab to represent the propagation of crack. Deterioration of bridge deck subjected to passages of five-axle double-unit trucks in Thailand is investigated to demonstrate the application of the simulated S-N relations.
Application of Full Depth Side Plate to Moment Connection of I-Beam to Double-I Column
Authors: Shiravand M.R. , Deylami A.
Published: December 2010

Double-I built-up columns are used extensively in low and medium rise steel structures. These sections have inherent compression, torsion and bending strength in all directions. The open sides of this type of column are covered with plates. When I beams are connected to double-I built-up columns through the column cover plate, the load transfer at the joint becomes a disturbing problem. To modify the connection, the authors propose a special type of connection using side plates. In this method the end of a beam is connected to the column by full depth side plates instead of direct welding of the beam ends to the column. The new geometry eliminates the traditional welded connection between the end of the beam and the face of the column. A series of eight non-linear, three dimensional finite elements models were developed to study the behaviour of the connection under cyclic loadings. The results obtained from the numerical analyses indicate that the proposed connection geometry has sufficient strength and ductility to be applied in “special moment frames (SMF)” as a “full strength” connection.
Seismic Response of a Steel Trussed Arch Structure to Spatially Varying Earthquake Ground Motions Including Site Effect
Authors: Bai Feng-Long , Hao Hong , Li Hong-Nan
Published: December 2010

This paper investigates seismic response of a realistic large dimension steel trussed arch structure subjected to the combined spatially varying horizontal and vertical ground motions. The ground motion spatial variations associated with wave passage effect, coherency loss effect and local site effect are considered. In numerical calculations, the simulated spatially varying ground motions are individually compatible with response spectrum defined in Chinese Seismic Design Code, and are compatible with an empirical coherency loss function between each other. Compared with structural responses calculated using uniform and delayed excitations, numerical results show that seismic response is amplified when spatially varying ground motions including local site effect are considered. Each factor of ground motion spatial variations has a significant effect on the dynamic response of the structure. Numerical results also indicate that considering simultaneous vertical and horizontal ground motions will lead to more accurate response predictions of the trussed arch as compared with those obtained by considering horizontal excitations only. Therefore, to have an accurate structural response assessment and a better design of long span steel trussed arch structures, a reliable ground motion spatial variation model is essential.
Ageing Behaviour of Natural Rubber and High Damping Rubber Materials Used in Bridge Rubber Bearings
Authors: Gu H.S. , Itoh Y.
Published: December 2010

This paper attempts to reveal the ageing behaviour of natural rubber (NR) and high damping rubber (HDR) materials used in bridge rubber bearings. Using various degradation factors such as thermal oxidation, ultraviolet, ozone, low temperature ozone, salt water and acid rain, a series of environmental accelerated ageing tests were conducted to investigate the ageing characteristics at the material level. The artificial weathering tests last from 4 days to more than 300 days. The mechanical properties such as stiffness, elongation at fracture, and tensile strength are evaluated through the uniaxial tensile test. The test results made clear that thermal oxidation is the dominant degradation factor, which hardens the rubbers and results in a significant drop in performance. Using the Arrhenius methodology, it is possible to estimate the future properties of NR and HDR at any temperature. This study is fundamental to predicting the lifecycle of bridge rubber bearings.
Energy-Based Modal Pushover Procedure for Asymmetric Structures
Authors: Li Ning , Zhai Changhai , Li Zhongxian , Hu Jinjun , Xie Lili
Published: December 2010

Energy-based seismic evaluations of structures can give clear illustrations of seismic demands made upon structures. This paper presents a 3-dimensional energy-based modal pushover analysis (3D EMPA) method with equivalent three degree of freedom (ETDOF) system and equal-displacement rule. The lateral-rotational coupled effect on structures asymmetric in plan is considered using the energy-based modal pushover analysis (EMPA), which is more robust than the traditional Modal Pushover Analysis (MPA) procedure. The proposed procedure was validated against a nonlinear time history analysis of a 5-storey structure. The results show that the method is able to take higher mode effects into account and that the instability of capacity spectra will be avoided. The maximum deformation obtained from EMPA shows good agreement with a nonlinear time history analysis results of the original system. The proposed EMPA procedure appears to be reliable and effective for evaluating the seismic response of asymmetric-plan structures.