bluuebunny/crossref_metadata_2025 huggingface dataset:
Alterations in hippocampal serotonergic and INSR function in streptozotocin induced diabetic rats exposed to stress: neuroprotective role of pyridoxine and Aegle marmelose
Authors: Abraham Pretty Mary , Kuruvilla Korah P , Mathew Jobin , Malat Anitha , Joy Shilpa , Paulose CS
Published: September 2010

Diabetes and stress stimulate hippocampal 5-HT synthesis, metabolism and release. The present study was carried out to find the effects of insulin,Aegle marmelosealone and in combination with pyridoxine on the hippocampal 5-HT, 5-HT2Areceptor subtype, gene expression studies on 5-HT2A, 5-HTT, INSR, immunohistochemical studies and elevated plus maze in streptozotocin induced diabetic rats. 5-HT content showed a significant decrease (p< 0.001) and a significant increase (p< 0.001) in 5-HIAA in hippocampus of diabetic rats compared to control. 5-HT receptor binding parameters Bmaxand Kdshowed a significant decrease (p< 0.001) whereas 5-HT2Areceptor binding parameters Bmaxshowed a significant decrease (p< 0.001) with a significant increase (p< 0.05) in Kdin hippocampus of diabetic rats compared to control. Gene expression studies of 5-HT2A,5-HTT and INSR in hippocampus showed a significant down regulation (p< 0.001) in diabetic rats compared to control. Pyridoxine treated in combination with insulin andA. marmeloseto diabetic rats reversed the 5-HT content, Bmax, Kdof 5-HT, 5-HT2Aand gene expression of 5-HT2A, 5-HTT and INSR in hippocampus to near control. The gene expression of 5-HT2Aand 5-HTT were confirmed by immunohistochemical studies. Behavioural studies using elevated plus maze showed that serotonin through its transporter significantly increased (p < 0.001) anxiety-related traits in diabetic rats which were corrected by combination therapy. Our results suggest that pyridoxine treated in combination with insulin andA. marmelosehas a role in the regulation of insulin synthesis and release, normalising diabetic related stress and anxiety through hippocampal serotonergic function. This has clinical significance in the management of diabetes.
Multispectral fingerprinting for improved in vivo cell dynamics analysis
Authors: Kulesa Paul M , Teddy Jessica M , Smith Miranda , Alexander Richard , Cooper Cameron HJ , Lansford Rusty , McLennan Rebecca
Published: September 2010

Background

Tracing cell dynamics in the embryo becomes tremendously difficult when cell trajectories cross in space and time and tissue density obscure individual cell borders. Here, we used the chick neural crest (NC) as a model to test multicolor cell labeling and multispectral confocal imaging strategies to overcome these roadblocks.

Results

We found that multicolor nuclear cell labeling and multispectral imaging led to improved resolution of in vivo NC cell identification by providing a unique spectral identity for each cell. NC cell spectral identity allowed for more accurate cell tracking and was consistent during short term time-lapse imaging sessions. Computer model simulations predicted significantly better object counting for increasing cell densities in 3-color compared to 1-color nuclear cell labeling. To better resolve cell contacts, we show that a combination of 2-color membrane and 1-color nuclear cell labeling dramatically improved the semi-automated analysis of NC cell interactions, yet preserved the ability to track cell movements. We also found channel versus lambda scanning of multicolor labeled embryos significantly reduced the time and effort of image acquisition and analysis of large 3D volume data sets.

Conclusions

Our results reveal that multicolor cell labeling and multispectral imaging provide a cellular fingerprint that may uniquely determine a cell's position within the embryo. Together, these methods offer a spectral toolbox to resolve in vivo cell dynamics in unprecedented detail.
Complete genome and comparative analysis of the chemolithoautotrophic bacterium Oligotropha carboxidovorans OM5
Authors: Paul Debarati , Bridges Susan M , Burgess Shane C , Dandass Yoginder S , Lawrence Mark L
Published: September 2010

Background

Oligotropha carboxidovorans OM5 T. (DSM 1227, ATCC 49405) is a chemolithoautotrophic bacterium capable of utilizing CO (carbon monoxide) and fixing CO2 (carbon dioxide). We previously published the draft genome of this organism and recently submitted the complete genome sequence to GenBank.

Results

The genome sequence of the chemolithoautotrophic bacterium Oligotropha carboxidovorans OM5 consists of a 3.74-Mb chromosome and a 133-kb megaplasmid that contains the genes responsible for utilization of carbon monoxide, carbon dioxide, and hydrogen. To our knowledge, this strain is the first one to be sequenced in the genus Oligotropha, the closest fully sequenced relatives being Bradyrhizobium sp. BTAi and USDA110 and Nitrobacter hamburgiensis X14. Analysis of the O. carboxidovorans genome reveals potential links between plasmid-encoded chemolithoautotrophy and chromosomally-encoded lipid metabolism. Comparative analysis of O. carboxidovorans with closely related species revealed differences in metabolic pathways, particularly in carbohydrate and lipid metabolism, as well as transport pathways.

Conclusion

Oligotropha, Bradyrhizobium sp and Nitrobacter hamburgiensis X14 are phylogenetically proximal. Although there is significant conservation of genome organization between the species, there are major differences in many metabolic pathways that reflect the adaptive strategies unique to each species.
Apoptosis-associated microRNAs are modulated in mouse, rat and human neural differentiation
Authors: Aranha Márcia M , Santos Daniela M , Xavier Joana M , Low Walter C , Steer Clifford J , Solá Susana , Rodrigues Cecília MP
Published: September 2010

Background

MicroRNAs (miRs or miRNAs) regulate several biological processes in the cell. However, evidence for miRNAs that control the differentiation program of specific neural cell types has been elusive. Recently, we have shown that apoptosis-associated factors, such as p53 and caspases participate in the differentiation process of mouse neural stem (NS) cells. To identify apoptosis-associated miRNAs that might play a role in neuronal development, we performed global miRNA expression profiling experiments in NS cells. Next, we characterized the expression of proapoptotic miRNAs, including miR-16, let-7a and miR-34a in distinct models of neural differentiation, including mouse embryonic stem cells, PC12 and NT2N cells. In addition, the expression of antiapoptotic miR-19a and 20a was also evaluated.

Results

The expression of miR-16, let-7a and miR-34a was consistently upregulated in neural differentiation models. In contrast, expression of miR-19a and miR-20a was downregulated in mouse NS cell differentiation. Importantly, differential expression of specific apoptosis-related miRNAs was not associated with increased cell death. Overexpression of miR-34a increased the proportion of postmitotic neurons of mouse NS cells.

Conclusions

In conclusion, the identification of miR-16, let-7a and miR-34a, whose expression patterns are conserved in mouse, rat and human neural differentiation, implicates these specific miRNAs in mammalian neuronal development. The results provide new insights into the regulation of neuronal differentiation by apoptosis-associated miRNAs.
Activating Transcription Factor 3 regulates in part the enhanced tumour cell cytotoxicity of the histone deacetylase inhibitor M344 and cisplatin in combination
Authors: St Germain Carly , O'Brien Anna , Dimitroulakos Jim
Published: September 2010

Background

Activating Transcription Factor (ATF) 3 is a key regulator of the cellular integrated stress response whose expression has also been correlated with pro-apoptotic activities in tumour cell models. Combination treatments with chemotherapeutic drugs, such as cisplatin, and histone deacetylase (HDAC) inhibitors have been demonstrated to enhance tumour cell cytotoxicity. We recently demonstrated a role for ATF3 in regulating cisplatin-induced apoptosis and others have shown that HDAC inhibition can also induce cellular stress. In this study, we evaluated the role of ATF3 in regulating the co-operative cytotoxicity of cisplatin in combination with an HDAC inhibitor.

Results

The HDAC inhibitor M344 induced ATF3 expression at the protein and mRNA level in a panel of human derived cancer cell lines as determined by Western blot and quantitative RT-PCR analyses. Combination treatment with M344 and cisplatin lead to increased induction of ATF3 compared with cisplatin alone. Utilizing the MTT cell viability assay, M344 treatments also enhanced the cytotoxic effects of cisplatin in these cancer cell lines. The mechanism of ATF3 induction by M344 was found to be independent of MAPKinase pathways and dependent on ATF4, a known regulator of ATF3 expression. ATF4 heterozygote (+/-) and knock out (-/-) mouse embryonic fibroblast (MEF) as well as chromatin immunoprecipitation (ChIP) assays were utilized in determining the mechanistic induction of ATF3 by M344. We also demonstrated that ATF3 regulates the enhanced cytotoxicity of M344 in combination with cisplatin as evidenced by attenuation of cytotoxicity in shRNAs targeting ATF3 expressing cells.

Conclusion

This study identifies the pro-apoptotic factor, ATF3 as a novel target of M344, as well as a mediator of the co-operative effects of cisplatin and M344 induced tumour cell cytotoxicity.
Expression of glypican 3 in placental site trophoblastic tumor
Authors: Ou-Yang Robin J , Hui Pei , Yang Ximing J , Zynger Debra L
Published: September 2010

Background

Glypican-3 (GPC3) is a membrane-bound heparan sulfate proteoglycan that functions in embryonic cell growth and differentiation and is highly expressed in the placenta. GPC3 is mutated in Simpson-Golabi-Behmel syndrome, which is characterized by tissue overgrowth and an increased risk of embryonal malignancies. GPC3 has also been implicated in sporadic cancer, particularly hepatocellular carcinoma, for which it has been shown to be a useful diagnostic marker. Although GPC3 expression has been studied in non-neoplastic placental tissue, its presence in gestational trophoblastic diseases has not been previously explored. The purpose of this study was to investigate the immunohistochemical expression of GPC3 in placental site trophoblastic tumor (PSTT), a very rare gestational trophoblastic neoplasm which may be morphologically confused with non-trophoblastic tumors, and to assess its possible utility as a diagnostic marker.

Methods

Fifteen cases of PSTT, as well as samples from placental site nodule (PSN) (n = 2), leiomyosarcoma (n = 1), leiomyoma (n = 1), invasive cervical squamous cell carcinoma (n = 7) and endometrial adenocarcinoma (n = 11) were examined. Immunoreactivity was semi-quantitatively evaluated as negative (0, < 5% of cells stained), focally positive (1+, 5-10% of cells stained), positive (2+, 11-50% of cells stained) or diffusely positive (3+, > 50% of cells stained). Staining intensity for each subtype was graded from 0 to 3 and a mean intensity was calculated.

Results

Eighty percent of PSTT (12/15) were immunoreactive for GPC3 (0, 20; 1+, 20%; 2+, 40%; 3+, 20%) with a mean intensity of 1.3. Stronger, predominately cytoplasmic staining was seen in larger multi- and mononucleated cells with smaller mononucleate cells showing weak muddy cytoplasmic staining. Both PSN cases were positive (1+, 50%; 2+, 50%) and two of nine invasive cervical squamous cell carcinomas showed staining (0, 57%; 1+, 29%; 2+, 14%), predominately in a basal distribution. Other uterine tumors and non-neoplastic tissues were negative.

Conclusions

Identification of GPC3 in PSTT and PSN is consistent with the derivation of these lesions from intermediate trophoblasts, which have been described to express GPC3. GPC3 may be a useful adjunct immunohistochemical marker in differentiating PSTT from non-trophoblastic tumors.
LNCaP Atlas: Gene expression associated with in vivoprogression to castration-recurrent prostate cancer
Authors: Romanuik Tammy L , Wang Gang , Morozova Olena , Delaney Allen , Marra Marco A , Sadar Marianne D
Published: September 2010

Background

There is no cure for castration-recurrent prostate cancer (CRPC) and the mechanisms underlying this stage of the disease are unknown.

Methods

We analyzed the transcriptome of human LNCaP prostate cancer cells as they progress to CRPC in vivo using replicate LongSAGE libraries. We refer to these libraries as the LNCaP atlas and compared these gene expression profiles with current suggested models of CRPC.

Results

Three million tags were sequenced using in vivo samples at various stages of hormonal progression to reveal 96 novel genes differentially expressed in CRPC. Thirty-one genes encode proteins that are either secreted or are located at the plasma membrane, 21 genes changed levels of expression in response to androgen, and 8 genes have enriched expression in the prostate. Expression of 26, 6, 12, and 15 genes have previously been linked to prostate cancer, Gleason grade, progression, and metastasis, respectively. Expression profiles of genes in CRPC support a role for the transcriptional activity of the androgen receptor (CCNH, CUEDC2, FLNA, PSMA7), steroid synthesis and metabolism (DHCR24, DHRS7, ELOVL5, HSD17B4, OPRK1), neuroendocrine (ENO2, MAOA, OPRK1, S100A10, TRPM8), and proliferation (GAS5, GNB2L1, MT-ND3, NKX3-1, PCGEM1, PTGFR, STEAP1, TMEM30A), but neither supported nor discounted a role for cell survival genes.

Conclusions

The in vivo gene expression atlas for LNCaP was sequenced and support a role for the androgen receptor in CRPC.
Intravenous administration of anti-vascular endothelial growth factor humanized monoclonal antibody bevacizumab improves articular cartilage repair
Authors: Nagai Toshihiro , Sato Masato , Kutsuna Toshiharu , Kokubo Mami , Ebihara Goro , Ohta Naoshi , Mochida Joji
Published: September 2010

Introduction

In this study, we investigate the efficacy of repairing an osteochondral defect in rabbit knee joints by administering bevacizumab, a humanized monoclonal anti-vascular endothelial growth factor (VEGF) antibody.

Methods

An osteochondral defect was created on the patellar groove of 20 Japanese white rabbits that were classified into two recipient groups: group B, administration of bevacizumab (100-mg intravenous injection on the day of surgery and 2 weeks later), and a control group (defect only). Rabbits were killed 1 and 3 months postoperatively. Sections were stained with safranin O. Repair sites were evaluated using the modified O'Driscoll International Cartilage Repair Society grading system. The expression of chondromodulin (ChM)-I and VEGF was evaluated using immunohistochemical analyses.

Results

At 1 month postoperatively, the repair site in group B was filled with cartilaginous tissue. At 3 months, the repair site retained this cartilage phenotype. At 1 month in the controls, the defects were mainly filled with fibrous tissue. At 3 months, the defect was replaced by fibrous tissue and bone. Over the 3-month period, histological scores were significantly higher in group B than in the controls. At 1 month, group B showed intense positive results for ChM-I in the bottom of the repair tissue. VEGF was also identified in the same area. In the controls, no ChM-I was observed in the repair tissue. Conversely, the remodeling hypertrophic chondrocyte layer stained intensely for VEGF.

Conclusions

Intravenous administration of bevacizumab contributes to better repair of articular cartilage in an osteochondral defect model. We suggest the possibility of facilitating articular cartilage repair with anti-VEGF antibody rather than using cultured cells or artificial scaffolds.
Convergence Rate of Extremes for the General Error Distribution
Authors: Peng Zuoxiang , Nadarajah Saralees , Lin Fuming
Published: September 2010

Let {Xn, n ≥ 1} be an independent, identically distributed random sequence with each Xn having the general error distribution. In this paper we derive the exact uniform convergence rate of the distribution of the maximum to its extreme value limit.
Looking Forwards and Backwards in the Multi-Allelic Neutral Cannings Population Model
Authors: Möhle M.
Published: September 2010

We look forwards and backwards in the multi-allelic neutral exchangeable Cannings model with fixed population size and nonoverlapping generations. The Markov chainXis studied which describes the allelic composition of the population forward in time. A duality relation (inversion formula) between the transition matrix ofXand an appropriate backward matrix is discussed. The probabilities of the backward matrix are explicitly expressed in terms of the offspring distribution, complementing the work of Gladstien (1978). The results are applied to fundamental multi-allelic Cannings models, among them the Moran model, the Wright-Fisher model, the Kimura model, and the Karlin and McGregor model. As a side effect, number theoretical sieve formulae occur in these examples.
Asymptotic Normality of Discrete-Time Markov Control Processes
Authors: Mendoza-Pérez Armando F. , Hernández-Lerma Onésimo
Published: September 2010

In this paper we study the asymptotic normality of discrete-time Markov control processes in Borel spaces, with possibly unbounded cost. Under suitable hypotheses, we show that the cost sequence is asymptotically normal. As a special case, we obtain a central limit theorem for (noncontrolled) Markov chains.
Low-cost topical negative pressure wound dressing system
Authors: Gnanaraj J
Published: September 2010

Poorly healing wounds are a bane to any surgical unit, but particularly in rural areas, and require a lot of effort to manage. One of the most effective recent methods that has been described is the application of topical negative pressure. We describe here a simple system made from the locally available materials that achieves this effect.
Improving Semantic Web Services Composition Performance, Using Data Mining Techniques
Authors: Bayati Shahab , Bahreininejad Ardeshir , Nejad Ali Farahmand , Kharazmi Ssdegh
Published: September 2010

There are many usages for the Web services in the World Wide Web. For creating new services we can compose other developed services in the way we want to use them. The large amount of Web services make composing of services a time consuming and impossible job. So to compose services some automated and semi-automated ways were developed. One of these ways is semantic Web services (SWS). In this paper we propose a method based on data mining techniques on Web services to find the best composition among possible compositions to improve quality and performance of Web service composition. Association rules, Classification and clustering are used as data mining approach to improve performance of the Web Service Composition
An Architectural Framework for the Development of Secure Mobile Payment System
Authors: Britto S. , Kumar R. , Rabara S. Albert
Published: September 2010

The Research in software architecture is an emerging field which emphasis on development methodologies, building theory, models of architecture, quality requirements, architectural description languages, and verification of architectural properties. Researchers put on efforts to elicit the state-of-the art technology framework in software architecture models in diversified fields. The high market penetrations of mobile personal devices including mobile phones, PDAs have paved a way for the development of new models in Mobile Commerce. Mobile phones are well suited with mobile commerce to reach the customers anywhere and at any time. Mobile Payments are a natural evolution of e-payment schemes that facilitate mobile commerce. A study reveals that there are wide ranges of mobile payment solutions and models available with the aid of various services. This paper provides a panoramic view of research in Software Architecture framework. A framework is to perform secure mobile payment system with the aim of achieving end-to-end security using asymmetric-key operations to provide convenient payment solutions. The development of secured mobile payment system for macro payments is a hot research topic for the research community and telecommunication industry. This paper proposes an effective framework to carry out the financial transactions from the customer to the merchant. It helps the application designers, developers and researchers to develop and manage the future payment applications and technologies.
A Generic Optimization Framework for Mobile Gis Queries
Authors: Elariss Haifa Elsidani , Khaddaj Souheil
Published: September 2010

With the increase in the number of non-expert mobile-users, applications have recently been developed to query Geographic Information Systems (GIS) particularly Location Based Services where users ask questions related to their position whether they are moving (dynamic) or not (static). Proximity analysis deals with queries that find k-nearest-neighbours and objects within a buffer-area, each of which being called an operator. Each operator corresponds to an execution plan to be executed by the GIS server. Since commonalities exist between the execution plans, the same common operations are executed many times leading to slow results. Hence, the need arises to develop a multi-user complex query optimizer that handles commonalities and processes the queries faster. We present a new query processor, a generic optimization framework for GIS and a middleware, which employs a new Query Melting paradigm (QM) that is based on the sharing paradigm and push-down optimization strategy. QM is implemented using a new Melting-Ruler strategy that melts repetitions in plans to share spatial areas, temporal intervals, objects, intermediate results, maps, user locations, and functions, thus produce time-cost effective results. It is illustrated using a sample tourist mobile GIS system and an Iconic Visual Query Language (IVQL) that was developed to formulate queries.
ERP Implementation the Blindspot in Software Engineering
Authors: Maureen Hopcroft , Michael Goodland
Published: September 2010

The primary focus of software engineering (SE) has been on bespoke work, but many organisations now adopt a strategy of using Commercial-off-the-Shelf (COTS) products and Enterprise Resource Planning (ERP) systems to meet their requirements. The availability of extensive pre-existing functionality in these should reduce risk and improve performance and hence SE has not focused on this area. However, the Standish Group1 estimates only 10% of ERP implementations succeed with full functionality. Modern SE processes are comparable to those adopted by ERP business implementers, but do not overtly address ERP specific issues. Hence, they offer insufficient guidance to organisations and practitioners. The key issue is that, given pre-existing functionality, organisations need to make significant strategic and tactical decisions about whether to change the business to fit the system or whether to change the system to fit the business. This paper examines the current level of software process support for ERPs and the consequent implications for research. It analyses these issues from a theoretical and practical perspective, by relating the experience of ERP implementation to current and emerging SE processes.
Finite State Automata Evolution Using Modular Architecture
Authors: Jindal Rajni , Singhai Shraddha
Published: September 2010

The automatic creation of finite automata has long been a goal of the evolutionary computation community. The previous works in the evolution of finite state automata were limited to the evolution of strictly non-modular FSA. Here, a modular architecture to evolve FSA is proposed and a genetic programming procedure for evolving such structures is presented. Results on the Tomita Language benchmark indicate that the proposed procedure is indeed capable of successfully evolving modular FSA and that such modularity can result in a significantly increased rate of optimization.
Software Metrics for the Evaluation of Semantic Web Applications
Authors: John Biju , Khaddaj Souheil , Hoppe Andreas
Published: September 2010

Semantic web sites that are designed and developed using well defined software quality parameters particularly those related to customers' satisfaction should perform well over the global business. In this paper several parameters are considered and a parameter matrix is proposed. A number of leading websites have been evaluated using this matrix and the evaluation results are presented.
Quality of Service Issues in Distributed Component Based Environments
Authors: Khaddaj S
Published: September 2010

The use of distributed component based environments and architectures in the software development lifecycle has increased significantly over recent years particularly with the adoption of service orientation in the form of Service-Oriented Architectures and Web Services. As more applications are based on the component paradigm, Quality of Service (QoS) issues have grown to become imperative since it is essential to achieve the desired QoS on resources assembled dynamically from enterprise, service provider, and customer systems. In this work some of the many of aspects of QoS for component based development are investigated and the metrics and measurement approaches that can be used are considered. Although they are generic it is relatively straightforward to drill down from a generic quality attributes, such as performance or reliability, until measurable and controllable quality attributes are identified.
Semantic Web for E-Governance
Authors: Kumbhar Manisha A. , Kumbhar Anil D. , Gavekar Vidya
Published: September 2010

The importance of Web services has been recognized and widely accepted by industry and academic research. This paper describes an ongoing research project involving the implementation of e-Governance services on the Semantic Web. In Today's IT world, technology enhanced e-governance system is lacking the concept of resource sharing and operation integration. A citizen has go through related services to satisfy his particular needs, which takes lot of time. Semantic web (SW) has potential to overcome this problem. SW technology provides foundation to enable exchange of knowledge and information to co-ordinate business processes. It can automatically compose web services through automatic discovery, selection & execution of web services. This research paper is highlighting an introduction to SW & other aspects like Ontology, Knowledge Management, Web Services & their approaches. Also highlights on the e-governance concept, discuses role of SW in e-governance services, its application areas and challenges with help of primary research work based on secondary data.
Global SOA Architectural Style – SOA for End Users
Authors: Shah Deven , Vyas Vaibhav , Vyas Vishal , Patel Dhiren
Published: September 2010

Interoperability, reusability and platform independence is the current need of the era. SOA was introduced with this in mind but it is mainly used only within the preconfigured and static environment of enterprise. SOA cannot satisfy the needs to dynamically discover the service and securely communicate with it over the internet. This concern entails a rethink of the SOA architecture. Our major focus is to make SOA truly global for use over internet for almost all the applications worldwide. Global SOA is a revolutionary idea of assigning every surfer an identity through agent Web Service to which it can delegate the work. We propose that the agent Web Service to be made so intelligent and dynamic that it will dynamically discover Web Services over the internet, communicate with it, dynamically configure the SOAP packets as per the security algorithm required by remote service and make decisions on users behalf.
Autonomous Flight at Low Altitude Using Light Sensors and Little Computational Power
Authors: Zufferey Jean-Christophe , Beyeler Antoine , Floreano Dario
Published: September 2010

The ability to fly at low altitude while actively avoiding collisions with the terrain and objects such as trees and buildings is a great challenge for small unmanned aircraft. This paper builds on top of a control strategy called optiPilot whereby a series of optic-flow detectors pointed at divergent viewing directions around the aircraft main axis are linearly combined into roll and pitch commands using two sets of weights. This control strategy already proved successful at controlling flight and avoiding collisions in reactive navigation experiments. This paper describes how optiPilot can efficiently steer a flying platform during the critical phases of hand-launched take off and landing. It then shows how optiPilot can be coupled with a GPS in order to provide goal-directed, nap-of-the-earth flight control in presence of obstacles. Two fully autonomous flights of 25 minutes each are described where a 400-gram unmanned aircraft flies at approx. 10 m above ground in a circular path including two copses of trees requiring efficient collision avoidance actions.
On Low Altitude Flight through the Atmospheric Boundary Layer
Authors: Watkins S. , Thompson M. , Loxton B. , Abdulrahim M.
Published: September 2010

Major challenges to low speed micro flight are the transient and time-averaged velocities arising from the Atmospheric Boundary Layer (ABL), particularly turbulence a few metres above the ground. In this paper, existing data from meteorologists and wind engineers are reviewed and measurements dedicated to understanding the spatial and temporal velocity fields that MAVs experience are briefly described. Data from a wide variety of terrains are analysed, with the majority of data obtained in relatively well mixed turbulent flow (i.e. away from local effects such as buildings) and for conditions of nominally neutral stability. Spectra for data well removed from local effects exhibited the expected 5/3rds Kolmogorov law. Transient flow pitch angles were investigated (obtained from four small laterally displaced probes), in order to understand the possible roll and pitch inputs to MAVs. It was noted that for all data obtained the variation with lateral separation decreased relatively slowly with reducing separation down to the closest inter-probe spacing of 14mm. This effect is thought to explain the increasing piloting difficulties experienced in maintaining good roll control for decreasing scales of craft when any appreciable atmospheric winds are present.
Simulator Development for Transition Flight Dynamics of a VTOL MAV
Authors: Chu Diyang , Sprinkle Jonathan , Randall Ryan , Shkarayev Sergey
Published: September 2010

This paper presents the simulation and validation of models for transition between forward flight and hover for a micro air vehicle (MAV). A dynamical simulation environment is developed, based on measured aerodynamic properties of a fixed-wing tail-sitter MAV with vertical take-off and landing (VTOL) capabilities. The simulator is validated against recorded flight data of transition from forward flight to hover using the physical platform. Specifically, the flight transition maneuver in the vertical plane (vertical-to-horizontal and horizontal-to-vertical) is studied in detail. The development and evaluation of a VTOL MAV called Mini-Vertigo 2 (MV2) is presented. A non-linear longitudinal dynamic model of MV2 flight is derived, and semi-empirical aerodynamic formulas for thrust, lift, drag and pitching moment based on wind tunnel testing are applied to the dynamic model. Nonlinearities during transition to/from hover are addressed, and (using the developed dynamic model) a numerical vehicle dynamic simulator is presented. The MV2 autopilot is discussed and flight test data are presented. Flight data from pitch-up maneuvers was compared to results of simulations. This comparison enables the future application of the simulation system throughout the flight envelope. This work presents a significant extension of [1].
Modelling Horizontal Gas-Liquid Flow Using Averaged Bubble Number Density Approach
Authors: Li C. , Yeoh G. H. , Cheung S. C. P. , Tu J. Y.
Published: September 2010

In this study, the internal phase distributions of gas-liquid bubbly flow in a horizontal pipe have been predicted using the population balance model based on Average Bubble Number Density approach. Four flow conditions with average gas volume fraction ranging from 4.4% to 20% have been investigated. Predicted local radial distributions of void fraction, interfacial area concentration and gas velocity have been validated against the experimental data. In general, satisfactory agreements between predicted results and measured values have been achieved. For high superficial gas velocity, it has been ascertained that peak local void fraction of 0.7 with interfacial area concentration of 800 m−1 can be encountered near the top wall of the pipe. Some discrepancies have nonetheless been found between the numerical and experimental results at certain locations of the pipe. The insufficient resolution of the turbulent model in fully accommodating the strong turbulence in the current pipe orientation and the inclusion of additional interfacial force such as the prevalent bouncing force among bubbles remain some of the outstanding challenging issues need to be addressed in order to improve the prediction of horizontal gas-liquid bubbly flow.
Basic Approach for the Diagnosis of Concrete after Fire Exposure
Authors: Annerel Emmanuel , Taerwe Luc
Published: September 2010

Concrete structures have a good fire resistance. After the fire, depending on the amount of damage, they may be repaired and reused. However, knowledge is needed to do this in a systematic and scientific way. This paper describes the parameters influencing the residual compressive strength of heated concrete. Since this strength decreases with temperature, the temperatures inside the concrete need to be known to assess the remaining load bearing capacity of concrete members. Two assessment techniques are discussed in this paper. Firstly, the colour alterations of the concrete surface and of the aggregates are measured, from which colour paths are derived. The shape of these paths allows to distinguish different temperature zones. Secondly, due to thermal decomposition of the cement matrix and thermal cracking at the interfacial transition zone, an increase of the porosity is found. This internal damage can be measured by the weight increase found after immersing concrete cores under water.
Numerical and Experimental Evaluation of the Temperature Distribution Within Laminated Veneer Lumber (LVL) Exposed to Fire
Authors: Fragiacomo Massimo , Menis Agnese , Moss Peter , Buchanan Andrew , Clemente Isaia
Published: September 2010

The fire resistance evaluation of a timber member is an important and complex problem of structural design. In order to solve this problem, it is crucial to have reliable information on the temperature distribution within a timber cross-section exposed to fire, and to develop a numerical model for the prediction of such a quantity. The paper reports the experimental-numerical comparisons in terms of temperature distribution within a timber member made from radiata pine LVL (laminated veneer lumber) exposed to fire. The experimental tests were performed at the University of Canterbury and BRANZ (New Zealand) on 146×60, 300×105 and 360×133 mm LVL members. The temperature distribution was monitored using several thermocouples. The numerical results were obtained using the Abaqus FE code with different conductive models. The Eurocode 5 and Frangi's proposals led to similar results characterized by acceptable approximation close to the surface. Since the accuracy reduced for deeper fibres, a new proposal based on a different variation of the conductivity with the temperature was made. The proposal led to acceptable approximation throughout the tested cross-sections.
Analysis of Composite Floor Cellular Steel Beams in Fire
Authors: Nadjai Ali , Goodfellow Nathan , Tee Kong Fah , Ali Faris , Choi Sengkwan
Published: September 2010

The growing popularity of the use of cellular steel beams in composite floors comes at the same time as an increasing attention to the fire safety engineering design. The recommendation for their design in fire limit states remains very primitive and this is due to the lack of general research in this area. Four composite cellular steel beams were tested at the University of Ulster with two models of different steel geometries and loading conditions under monotonic loading and at elevated temperatures. This paper presents a finite element model and simple hand calculation methods to calculate the shear buckling at the web post, the bending resistance in fire, deflection and temperature distribution in the cross section of composite cellular beams.
Examination of the Mechanical Properties of Steel S460 for Fire
Authors: Lange Jörg , Wohlfeil Ninja
Published: September 2010

To establish a basis for calculating the load-bearing capacity of steel members made of S460 in a fire, corresponding to EN 1993-1-2, the mechanical properties of the micro-alloyed grain refined steel S460 under high temperatures have been examined. Two different types of steel have been considered: a normalized rolled S460 N and a thermo-mechanically rolled S460 M, that differ in their chemical composition and the temperature control during the hot-rolling process. On the basis of transient warm-creep tests, constitutive laws have been derived for the temperature range 20-900°C. The testresults show an increased strength of S460 M at elevated temperatures in comparison to S460 N. This is a result of the strain hardening caused by the thermo-mechanical rolling and the reduction of the creep-velocity caused by niobium- and titanium-precipitations. The data derived from the tests show that the stress-strain curves given in EN 1993-1-2 for S460 overestimate both the strength and the stiffness of the examined S460 N.
A New Methodology for the Assessment of the EoS Data of Concrete
Authors: Gebbeken N. , Hartmann T.
Published: September 2010

The experimental determination of the equation of state is a complex and expensive task. This paper presents a new methodology for the theoretical determination of the equation of state for concrete. Mesomechnical simulations are conducted and compared to three sets of experimental data. It was also investigated whether the methodology used for the meso-scale modeling is applicable to a homogenized description of concrete. Based on more than 400 numerical simulations, it is shown that the EoS parameters which are determined on a purely theoretical basis agree well with both the experimental and the numerical results on a meso-level. Hence, the provided theoretical methodology enables modelers to assess the EoS parameters of concrete for most applications in a simple spreadsheet analysis.
Investigation of Air-Blast Effects from Spherical-and Cylindrical-Shaped Charges
Authors: Wu Chengqing , Fattori Gianni , Whittaker Andrew , Oehlers Deric John
Published: September 2010

Although the distributions of peak incident overpressure and impulse generated from spherical charges and cylindrical charges of the same weight can differ greatly close to the point of detonation, spherical charges are assumed for nearly all explosive-effects computations per modern standards for blast-resistant design such as UFC-3-340-02 and the soon-to-be published ASCE Standard for the Blast Protection of Buildings. A blast-testing program was performed using a reinforced concrete slab as the target to investigate the reflected peak overpressure and impulse distributions as a function of charge shape, orientation, and scaled distance. The charge shapes were cylindrical and spherical, and the charge mass varied from 0.24 to 8.0 kg. Nine pressure transducers were installed on the surface of the slab to record the distribution of pressure histories over the face of the target. A finite element model of the explosive and the target was validated using the experimental data. The validated model was then used to undertake a parametric analysis to more broadly study the effects of detonation point, ratio of charge length to charge diameter, charge orientation and standoff distance on the distribution of reflected overpressure. Numerical results are compared with predictions of UFC-3-340-02. For cylindrical charges, the ratio of charge length ( L) to diameter ( D), the orientation of the longitudinal axis of the charge, and detonation point within the charge affected the distributions of reflected peak overpressure and impulse in the immediate vicinity of the explosive. The UFC-3-340-02 underpredicts substantially the reflected peak overpressure and impulse on a target aligned with the vertical axis of a cylindrical charge with an aspect ratio of 1.0.
Estimation of Deep Penetration Resistance with Spherical Specific Cavitation Energy
Authors: Masri Rami
Published: September 2010

A simple model is suggested for deep penetration resistance of rigid, axially-symmetric, nose-pointed projectiles penetrating ductile metal targets. Model is based on power balance between the power supplied by the projectile during steady-state penetration and elastoplastic power needed for expanding penetration hole. The latter is approximated with the aid of the spherical specific cavitation energy (spherical cavitation pressure). Frictionless model includes an empirical parameter which is found to be practically independent of target material characteristics but reflects the shape of head profile. For ogival nose projectiles (with the spherical nose as a special case) the empirical parameter values are limited to a narrow range, slightly lower than one. Friction resistance is included by the Prandtl friction model leading to a general expression for the deep penetration hardness. Experimental data of spherical and ogival nose projectiles penetrating aluminium targets is compared with analytical predictions for penetration depth and an optimal ogival nose projectile is discussed.
Drop-Weight Impact Response of Fibre Reinforced Cement Based Foams
Authors: Mamun Muhammad , Bindiganavile Vivek
Published: September 2010

This paper describes the strength and toughness of fibre reinforced cement based foams subjected to bending under variable strain rates. Drop-weight impact tests were conducted on notched beams with cast density between 475 kg/m3 to 1200 kg/m3. The foams were reinforced with 0–0.2% polypropylene microfibre by volume and their role in improving the dynamic properties is illustrated. The structure of the cell wall within the foams was engineered through a suitable choice of foaming agent, such that foams with a predominantly closed cell structure were produced. Companion tests were conducted as per ASTM standards in compression and flexure under quasi-static loading. The results were compared to other brittle cellular solids from the literature, and the mechanical properties are described in terms of the relative density, defined as the ratio of the density of the cellular composite relative to that of Portland cement paste in the cell wall. The study shows that under quasi-static loading, the compressive strength, elastic modulus and modulus of rupture of plain mixes scale with the square of the relative density. On the other hand, the flexural toughness factor scaled linearly with it. Fibres were seen to increase the flexural strength at all rates of loading, regardless of cast density. However, the Poisson's ratio remained unaffected by the density of the mix. Further, cement based foams were seen to be strain rate sensitive but, the existing CEB-FIP model for cementitious materials vastly overestimates the dynamic impact factor at lower cast densities.
Numerical and Experimental Investigations on the Blast-Resistant Properties of Arched RC Blast Doors
Authors: Li Chen , Qin Fang , Ya-Dong Zhang , Yi Zhang , Jun-Yu Fan
Published: September 2010

In order to have a clear understanding of the blast-resistant properties of blast doors, full scale in-situ tests of an arched reinforced concrete blast door subjected to explosions outside a tunnel entrance were carried out. An elaborative three-dimensional FE analysis was conducted to numerically evaluate the structural response of the blast door. The blast loads applied on the door in the FE analysis were simulated by using the FE program AUTODYN and simplified to be triangular loads without consideration of the rising time. The dynamic responses of the tested blast door under single and multiple blast loads were analyzed by using the FE program ABAQUS which adopted a rate-sensitive material model combined with a concrete plastic damage model. The results of numerical simulation were compared with the experimental data. It is demonstrated that the strain-rate effects and nonlinear contacts between the door leaf and the doorframe steel plate as well as the enclaves and the steel tube have considerable influence on the responses of the arched reinforced concrete blast door. The mid-span displacement of the door increased with the increase of the number of explosions. The blast door finally failed after eight explosions.
Computational approaches toward the design of pools for the in vitro selection of complex aptamers
Authors: Luo Xuemei , McKeague Maureen , Pitre Sylvain , Dumontier Michel , Green James , Golshani Ashkan , Derosa Maria C. , Dehne Frank
Published: September 2010

It is well known that using random RNA/DNA sequences for SELEX experiments will generally yield low-complexity structures. Early experimental results suggest that having a structurally diverse library, which, for instance, includes high-order junctions, may prove useful in finding new functional motifs. Here, we develop two computational methods to generate sequences that exhibit higher structural complexity and can be used to increase the overall structural diversity of initial pools for in vitro selection experiments. Random Filtering selectively increases the number of five-way junctions in RNA/DNA pools, and Genetic Filtering designs RNA/DNA pools to a specified structure distribution, whether uniform or otherwise. We show that using our computationally designed DNA pool greatly improves access to highly complex sequence structures for SELEX experiments (without losing our ability to select for common one-way and two-way junction sequences).