bluuebunny/crossref_metadata_2025 huggingface dataset:
Health Assessment of Engineering Structures Using Graphical Models
Authors: Moustafa Abbas , Mahadevan Sankaran
Published: May 2012

A hybrid qualitative-quantitative health assessment of structures using the bond graph theory is presented in this chapter. Bond graph (BG) is an energy-based graphical-modeling tool for physical dynamic systems, actuators, and sensors. BG provides domain-independent framework for modeling dynamic systems with interacting components from multiple domains. Discrete structures are modeled using one-to-one bond graph elements, while continuous structures are modeled using finite-mode bond graphs. BG facilitates the construction of temporal causal graph (TCG) that links the system response to the damaged component or faulty sensor. TCG provides qualitative damage isolation, which is not possible using most existing system identification techniques. This leads to rapid isolation of damage and significant reduction in computations. Quantitative identification of damage size is performed by analyzing the substructure containing the damaged component, using the nonlinear least-squares optimization technique, thus reducing the computations. The health assessment algorithm developed in this chapter combines the Generic Modeling Environment (GME), the Fault Adaptive Control Technology (FACT) software, and Matlab Simulink®. Numerical illustrations on BG modeling of a hydraulic actuator and system identification of a fifteen-story shear building and a high-rise structure under earthquake loads are provided.
Optimal Design of Nonlinear Viscous Dampers for Protection of Isolated Bridges
Authors: Taflanidis Alexandros A. , Gidaris Ioannis G.
Published: May 2012

A probabilistic framework based on stochastic simulation is presented in this chapter for optimal design of supplemental dampers for multi - span bridge systems supported on abutments and intermediate piers through isolation bearings. The bridge model explicitly addresses nonlinear characteristics of the isolators and the dampers, the dynamic behavior of the abutments, and the effect of pounding between the neighboring spans to each other as well as to the abutments. A probabilistic framework is used to address the various sources of structural and excitation uncertainties and characterize the seismic risk for the bridge. Stochastic simulation is utilized for evaluating this seismic risk and performing the associated optimization when selecting the most favorable damper characteristics. An illustrative example is presented that considers the design of nonlinear viscous dampers for protection of a two-span bridge.
U.S. Regulatory Requirements for Positive Train Control Systems
Authors: Hartong Mark , Wijesekera Duminda
Published: May 2012

Positive Train Control (PTC) Systems are a type of Communications Based Train Control System (CBTC) designed to enhance railroad safety. As a consequence of a series of high profile train accidents in the United States, a statutory mandate for the installation of these systems in high risk areas by the end of 2015 has been established. This chapter identifies the impetus behind the statute, the statutory requirements associated with PTC, the implementing regulations for the statutory requirements, and the current status of regulatory compliance.
Semi-Quantitative Risk Assessment of Technical Systems on European Railways
Authors: Braband Jens
Published: May 2012

The European Railway Agency (ERA) has the challenging task of establishing common safety targets and common safety methods throughout Europe. In this context, the harmonization of risk analysis methods is also discussed. The purpose of this paper is to present a new semi-quantitative approach for the risk analysis of technical systems and the means by which compliance with legal and regulatory requirements can be demonstrated. As a particular reference, a new German pre-standard, which lays out requirements for semi-quantitative approaches, is taken into account.
The ForMoSA Approach to Qualitative and Quantitative Model-Based Safety Analysis
Authors: Habermaier Axel , Güdemann Matthias , Ortmeier Frank , Reif Wolfgang , Schellhorn Gerhard
Published: May 2012

This chapter presents ForMoSA (FORmal MOdels and Safety Analysis), an integrated approach for the safety assessment of safety-critical embedded systems. The approach brings together the best of engineering practice, formal methods, and mathematics: traditional safety analysis, temporal logics and verification, as well as statistics and optimization. These three orthogonal techniques cover three different aspects of safety: fault tolerance, functional correctness, and quantitative analysis. The ForMoSA approach combines these techniques to assess system safety in a structured and formal way. Furthermore, the tight combination of methods from different analysis domains results in mutual benefits. The combined approach yields results which cannot be produced by any single technique on its own. The methodology was applied to several case studies from different industrial domains. One of them is an autonomous control of level crossings using radio-based communication, which is used in this chapter to describe the individual steps of the ForMoSA methodology.
Verification and Validation of Interoperability
Authors: Ebrecht Lars , Meyer zu Hörste Michael
Published: May 2012

The chapter shows an approach to use existing test methods to prove technical as well as operational interoperability. The first kinds of tests are test sequences to validate conformity of a single constituent – here, an on-board on-board unit (OBU) of the European Train Control System (ETCS) in the European Rail Traffic Management System (ERTMS). The second kind of tests is the integration test for assemblies – here, the complete on-board equipment. The third kinds of tests are the tests for the validation of operational serviceability. An approach for the stepwise integration of the different kinds of tests is shown. As a conclusion the perspective for the use of these test sequences in an independent test lab is given.
Mίνθa
Authors: Süß Jörn Guy , Robinson Neil , Carrington David , Strooper Paul
Published: May 2012

Implementation of railway controller application logic is a highly safety-critical and time-consuming task carried out individually for each client and station by specialised signalling engineers, with corresponding high costs. M???a is a software development framework designed to create code generators for application logic for the client railway companies of Ansaldo STS that use the Microlok II controller to lower the cost and increase repeatability. This chapter describes the evolution of M???a from prototype to framework, and introduces the software engineering approaches of object-oriented meta-modelling and framework development along the way. It also presents known limitations and further application areas of the framework.
Integration of Human Factors to Safety Assessments by Human Barrier Interaction
Authors: Talg Markus , Hammerl Malte , Meyer zu Hörste Michael
Published: May 2012

Human factors have a strong impact on railways safety. However, the assessments of these factors still follow traditional and inadequate approaches. While failure probabilities of technical systems can be measured in sufficient precision, human error probabilities are still estimated in a very rough and vague way. Upon this motivation, the contribution presents a method analyzing human influence in railway applications. The approach of human-barrier-interaction relies on a new model of human behavior, a classic model of human-machine-interaction and a model of safety measures by barriers. Applying the method, human reliability can be assessed in comparative way. An advantage over existing approaches is the substantial combination of cognitive psychology and engineering expertise without unpractical complexity.
Adoption of Low-Cost Rail Level Crossing Warning Devices
Authors: Wullems Christian , Nikandros George
Published: May 2012

The objective of this chapter is to provide rail practitioners with a practical approach for determining safety requirements of low-cost level crossing warning devices (LCLCWDs) on an Australian railway by way of a case study. LCLCWDs, in theory, allow railway operators to improve the safety of passively controlled crossing by upgrading a larger number of level crossings with the same budget that would otherwise be used to upgrade these using the conventional active level crossing control technologies, e.g. track circuit initiated flashing light systems. The chapter discusses the experience and obstacles of adopting LCLCWDs in Australia, and demonstrates how the risk-based approach may be used to make the case for LCLCWDs.
A Heuristic Approach for Multi Objective Distribution Feeder Reconfiguration
Authors: Milani Armin Ebrahimi , Haghifam Mahmood Reza
Published: May 2012

The reconfiguration is an operation process used for optimization with specific objectives by means of changing the status of switches in a distribution network. This paper presents an algorithm for network recon-figuration based on the heuristic rules and fuzzy multi objective approach where each objective is normalized with inspiration from fuzzy set to cause optimization more flexible and formulized as a unique multi objective function. Also, the genetic algorithm is used for solving the suggested model, in which there is no risk of non-linear objective functions and constraints. The effectiveness of the proposed method is demonstrated through several examples in this paper.
Extrapolated Biogeography-Based Optimization (eBBO) for Global Numerical Optimization and Microstrip Patch Antenna Design
Authors: Lohokare M. R. , Pattnaik S.S. , Devi S. , Panigrahi B.K. , Das S. , Joshi J. G.
Published: May 2012

Biogeography-Based Optimization (BBO) uses the idea of probabilistically sharing features between solutions based on the solutions’ fitness values. Therefore, its exploitation ability is good but it lacks in exploration ability. In this paper, the authors extend the original BBO and propose a hybrid version combined with ePSO (particle swarm optimization with extrapolation technique), namely eBBO, for unconstrained global numerical optimization problems in the continuous domain. eBBO combines the exploitation ability of BBO with the exploration ability of ePSO effectively, which can generate global optimum solutions. To validate the performance of eBBO, experiments have been conducted on 23 standard benchmark problems with a range of dimensions and diverse complexities and compared with original BBO and other versions of BBO in terms of the quality of the final solution and the convergence rate. Influence of population size and scalability study is also considered and results are compared with statistical paired t-test. Experimental analysis indicates that the proposed approach is effective and efficient and improves the exploration ability of BBO.
A DFT-Based Analysis to Discern Between Camera and Scanned Images
Authors: Caldelli Roberto , Amerini Irene , Picchioni Francesco
Published: May 2012

Digital images are generated by different sensors, understanding which kind of sensor has acquired a certain image could be crucial in many application scenarios where digital forensic techniques operate. In this paper a new methodology which permits to establish if a digital photo has been taken by a photo-camera or has been scanned by a scanner is presented. The specific geometrical features of the sensor pattern noise introduced by the sensor are investigated by resorting to a DFT (Discrete Fourier Transform) analysis and consequently the origin of the digital content is assessed. Experimental results are provided to witness the reliability of the proposed technique.
Blind Detection of Additive Spread-Spectrum Watermarking in the Dual-Tree Complex Wavelet Transform Domain
Authors: Kwitt Roland , Meerwald Peter , Uhl Andreas
Published: May 2012

In this paper, the authors adapt two blind detector structures for additive spread-spectrum image watermarking to the host signal characteristics of the Dual-Tree Complex Wavelet Transform (DT-CWT) domain coefficients. The research is motivated by the superior perceptual characteristics of the DT-CWT and its active use in watermarking. To improve the numerous existing watermarking schemes in which the host signal is modeled by a Gaussian distribution, the authors show that the Generalized Gaussian nature of Dual-Tree detail subband statistics can be exploited for better detector performance. This paper finds that the Rao detector is more practical than the likelihood-ratio test for their detection problem. The authors experimentally investigate the robustness of the proposed detectors under JPEG and JPEG2000 attacks and assess the perceptual quality of the watermarked images. The results demonstrate that their alterations allow significantly better blind watermark detection performance in the DT-CWT domain than the widely used linear-correlation detector. As only the detection side has to be modified, the proposed methods can be easily adopted in existing DT-CWT watermarking schemes.
Digital Image Splicing Using Edges
Authors: Weir Jonathan , Lau Raymond , Yan WeiQi
Published: May 2012

In this paper, the authors splice together an image which has been split up on a piece of paper by using duplication detection. The nearest pieces are connected using edge searching and matching and the pieces that have graphics or textures are matched using the edge shape and intersection between the two near pieces. Thus, the initial step is to mark the direction of each piece and put the pieces that have straight edges to the initial position to determine the profile of the whole image. The other image pieces are then fixed into the corresponding position by using the edge information, i.e., shape, residual trace and matching, after duplication or sub-duplication detection. In the following steps, the patches with different edge shapes are searched using edge duplication detection. With the reduction of rest pieces, the montage procedure will become easier and faster.
A Biologically Inspired Smart Camera for Use in Surveillance Applications
Authors: Haltis Kosta , Sorell Matthew J. , Brinkworth Russell
Published: May 2012

Biological vision systems are capable of discerning detail as well as detecting objects and motion in a wide range of highly variable lighting conditions that proves challenging to traditional cameras. In this paper, the authors describe the real-time implementation of a biological vision model using a high dynamic range video camera and a General Purpose Graphics Processing Unit. The effectiveness of this implementation is demonstrated in two surveillance applications: dynamic equalization of contrast for improved recognition of scene detail and the use of biologically-inspired motion processing for the detection of small or distant moving objects in a complex scene. A system based on this prototype could improve surveillance capability in any number of difficult situations.
Reducing the Perceived Risk of e-Government Implementations
Authors: Whitmore Andrew , Choi Namjoo
Published: May 2012

Perceived risk has been identified by the literature as a limiting factor in e-government adoption and success. However, there has been little effort spent examining how and why perceived risk comes to differ from actual probabilistic risk and the means by which the gap can be reduced. These questions were examined by applying the Social Amplification of Risk Framework to the case of e-government in the United States. Several factors that are known to exacerbate perceived risk were identified from the literature and shown to be in place in the United States. The presence of these factors suggests that more effective risk communication is required in order to realign perceived risk with probabilistic risk. Recommendations on how to improve e-government risk communication through technical and human means are provided.
E-Government Implementation Perspective
Authors: Shareef Mahmud Akhter , Kumar Vinod , Kumar Uma , Chowdhury Abdul Hannan , Misra Subhas C.
Published: May 2012

Though many countries are still just beginning to grasp the potential uses and impacts of Electronic-government (EG), advances in technologies and their applications continue. Observing the proliferation of EG, countries are increasingly turning to the Internet to market their EG system to gain a competitive advantage. However, the effectiveness and efficiency of such online government systems largely depends on the mission of implementing EG. For successful adoption and implementation of EG, it is essential that a country first identify an explicit objective and a specific strategy. We have examined implemention strategies of EG of seven diverse countries whose objectives and mission for implementing EG differ significantly. However, they have the following strategies in common: i) extensive application of information and communication technology (ICT) in the public sector; ii) overall reformation of the public sector; iii) development of a better quality service structure; and iv) more cohesive integration of citizens with government.
Comparing Citizens’ Use of E-Government to Alternative Service Channels
Authors: Reddick Christopher G.
Published: May 2012

This article examines the role e-government has over citizens’ when they initiate contact with their government. It also compares the influence that other contact channels have on citizens’ contacts with government. A public opinion survey is analyzed to determine what factors explain the different methods of contacting government, namely through the phone, e-government, visiting a government office, or a combination of approaches. This article also analyzes citizens’ preferred method of contacting government, examining different types of information or assistance that citizens’ can get from government. The results of this study indicate that e-government is just one of many possible service channels that citizens use, with the phone being the most common. The overall importance of the survey results indicate that e-government is just one contact channel for citizens, and resources should also be devoted towards other contact channels given their importance as well to citizens.
Engaging Citizens on the Internet
Authors: Cassell Mark , Hoornbeek John A.
Published: May 2012

This article presents empirical results relating to citizen-government relations on the internet that are based on an assessment of the World Wide Web presence of 428 local governments in northeast Ohio. Northeast Ohio provides a useful picture of E-government-citizen relationships because it includes a range of local government forms (counties, townships, etc.), urban and rural populations, and Midwestern influences that many consider “typical” of American states. The website reviews conducted assess citizen-government engagement in a variety of areas. The measures used include simple engagements like the ability to sign up for email updates and the presence of event calendars to more involved interactions, such as blogs, e-pay services, and open records requests. Using these measures, the authors assess citizen-government engagement among local governments in the sample.
Multimedia Databases and Data Management
Authors: Chen Shu-Ching
Published: May 2012

The exponential growth of the technological advancements has resulted in high-resolution devices, such as digital cameras, scanners, monitors, and printers, which enable the capturing and displaying of multimedia data in high-density storage devices. Furthermore, more and more applications need to live with multimedia data. However, the gap between the characteristics of various media types and the application requirements has created the need to develop advanced techniques for multimedia data management and the extraction of relevant information from multimedia databases. Though many research efforts have been devoted to the areas of multimedia databases and data management, it is still far from maturity. The purpose of this article is to discuss how the existing techniques, methodologies, and tools addressed relevant issues and challenges to enable a better understanding in multimedia databases and data management. The focuses include: (1) how to develop a formal structure that can be used to capture the distinguishing content of the media data in a multimedia database (MMDB) and to form an abstract space for the data to be queried; (2) how to develop advanced content analysis and retrieval techniques that can be used to bridge the gaps between the semantic meaning and low-level media characteristics to improve multimedia information retrieval; and (3) how to develop query mechanisms that can handle complex spatial, temporal, and/or spatio-temporal relationships of multimedia data to answer the imprecise and incomplete queries issued to an MMDB.
Multi-Label Classification Method for Multimedia Tagging
Authors: Ma Aiyesha , Sethi Ishwar K. , Patel Nilesh
Published: May 2012

Community tagging offers valuable information for media search and retrieval, but new media items are at a disadvantage. Automated tagging may populate media items with few tags, thus enabling their inclusion into search results. In this paper, a multi-label decision tree is proposed and applied to the problem of automated tagging of media data. In addition to binary labels, the proposed Iterative Split Multi-label Decision Tree (IS-MLT) is easily extended to the problem of weighted labels (such as those depicted by tag clouds). Several datasets of differing media types show the effectiveness of the proposed method relative to other multi-label and single label classifier methods and demonstrate its scalability relative to single label approaches.
An Image Clustering and Feedback-Based Retrieval Framework
Authors: Zhang Chengcui , Zhou Liping , Wan Wen , Birch Jeffrey , Chen Wei-Bang
Published: May 2012

Most existing object-based image retrieval systems are based on single object matching, with its main limitation being that one individual image region (object) can hardly represent the user’s retrieval target, especially when more than one object of interest is involved in the retrieval. Integrated Region Matching (IRM) has been used to improve the retrieval accuracy by evaluating the overall similarity between images and incorporating the properties of all the regions in the images. However, IRM does not take the user’s preferred regions into account and has undesirable time complexity. In this article, we present a Feedback-based Image Clustering and Retrieval Framework (FIRM) using a novel image clustering algorithm and integrating it with Integrated Region Matching (IRM) and Relevance Feedback (RF). The performance of the system is evaluated on a large image database, demonstrating the effectiveness of our framework in catching users’ retrieval interests in object-based image retrieval.
PLCA
Authors: Takahashi Kazuko
Published: May 2012

This chapter describes a framework called PLCA for Qualitative Spatial Reasoning (QSR) based on the connection patterns of regions. The goal of this chapter is to provide a simple but expressive and feasible representation for qualitative data with sufficient reasoning ability. PLCA provides a symbolic representation for spatial data using simple objects. The authors of this chapter define its expression and operations on it, and show the correspondance between the expression and a figure. PLCA also provides semantical reasoning incorporated with spatial reasoning. Moreover, it can be extended to handle shapes of regions. Throughout the study, the authors discovered many topics that relate QSR to other research areas such as topology, graph theory, and computational geometry, while achieving the research goals. This indicates that QSR is a very fruitful research area.
A Conceptual Model for Examining E-Government Adoption in Jordan
Authors: Alryalat Mohammad , Dwivedi Yogesh   K. , Williams Michael D.
Published: May 2012

In this paper, the authors propose and discuss a conceptual model for examining factors affecting e-government adoption in Jordan. This study evaluates existing empirical studies that examine e-government adoption in developing and under-developed countries. These studies were based on pre-existing theoretical models for explaining and guiding their research frameworks. An in-depth analysis of such models revealed that the technology acceptance model (TAM), the diffusion of innovation (DOI) theory, the theory of planned behaviour (TPB), and the unified theory of acceptance and use of technology (UTAUT) were among some of the most frequently used. As the UTAUT is a unified model based on the mapping of eight models, it was deemed appropriate to use the UTAUT as a guiding model for this research. A comprehensive analysis of all studies and constructs revealed that some external factors were also important for explaining e-gov adoption in developing countries. Hence, such external factors also considered relevant were integrated with UTAUT constructs as examining factors affecting e-gov adoption in Jordan. The theoretical and logical arguments and prior empirical validation of the constructs and their relationships allowed for the justification of the proposed integrated model and formulation of the associated hypotheses.
Six Sigma Approach to Improve Quality in E-Services
Authors: Alhyari Salah , Alazab Moutaz , Venkatraman Sitalakshmi , Alazab Mamoun , Alazab Ammar
Published: May 2012

This paper investigates the application of the Six Sigma approach to improve quality in electronic services (e-services) as more countries are adopting e-services as a means of providing services to their people through the Web. This paper presents a case study about the use of Six Sigma model to measure customer satisfaction and quality levels achieved in e-services that were recently launched by public sector organisations in a developing country, such as Jordan. An empirical study consisting of 280 customers of Jordan’s e-services is conducted and problems are identified through the DMAIC phases of Six Sigma. The service quality levels are measured and analysed using six main criteria: Website Design, Reliability, Responsiveness, Personalization, Information Quality, and System Quality. The study indicates a 74% customer satisfaction with a Six Sigma level of 2.12 has enabled the Greater Amman Municipality to identify the usability issues associated with their e-services offered by public sector organisations. The aim of the paper is not only to implement Six Sigma as a measurement-based strategy for improving e-customer service in a newly launched e-service programme, but also widen its scope in investigating other service dimensions and perform comparative studies in other developing countries.
Building Trust in E-Government Adoption through an Intermediary Channel
Authors: Al-Sobhi Faris , Weerakkody Vishanth , El-Haddadeh Ramzi
Published: May 2012

E-government has become an essential strategy for many governments in their efforts to increase accessibility and facilitate improved diffusion of public sector services. However, citizens’ adoption of online public services has been obstructed by factors such as, digital divide, accessibility, and trust. This study examines the influencing role that intermediaries can play in helping to facilitate the adoption of electronic government services. A case study is undertaken in Medinah City to explore how third party intermediary organisations can help in building trust, reduce digital divide and improve accessibility of public services to citizens. While the literature highlights extensively the challenges of e-government adoption and diffusion, the results of this exploratory study demonstrate that intermediaries can play a significant role in overcoming these potential challenges.
Transplanted Mesoangioblasts Require Macrophage IL-10 for Survival in a Mouse Model of Muscle Injury
Authors: Bosurgi Lidia , Corna Gianfranca , Vezzoli Michela , Touvier Thierry , Cossu Giulio , Manfredi Angelo A. , Brunelli Silvia , Rovere-Querini Patrizia
Published: May 2012

The aim of this study was to verify whether macrophages influence the fate of transplanted mesoangioblasts—vessel-associated myogenic precursors—in a model of sterile toxin-induced skeletal muscle injury. We have observed that in the absence of macrophages, transplanted mesoangioblasts do not yield novel fibers. Macrophages retrieved from skeletal muscles at various times after injury display features that resemble those of immunoregulatory macrophages. Indeed, they secrete IL-10 and express CD206 and CD163 membrane receptors and high amounts of arginase I. We have reconstituted the muscle-associated macrophage population by injecting polarized macrophages before mesoangioblast injection: alternatively activated, immunoregulatory macrophages only support mesoangioblast survival and function. This action depends on the secretion of IL-10 in the tissue. Our results reveal an unanticipated role for tissue macrophages in mesoangioblast function. Consequently, the treatment of muscle disorders with mesoangioblasts should take into consideration coexisting inflammatory pathways, whose activation may prove crucial for its success.
MAPK Regulation of IL-4/IL-13 Receptors Contributes to the Synergistic Increase in CCL11/Eotaxin-1 in Response to TGF-β1 and IL-13 in Human Airway Fibroblasts
Authors: Zhou Xiuxia , Hu Haizhen , Balzar Silvana , Trudeau John B. , Wenzel Sally E.
Published: May 2012

CCL11/eotaxin-1 is a potent eosinophilic CC chemokine expressed by primary human fibroblasts. The combination of TGF-β1 and IL-13 synergistically increases CCL11 expression, but the mechanisms behind the synergy are unclear. To address this, human airway fibroblast cultures from normal and asthmatic subjects were exposed to IL-13 alone or TGF-β1 plus IL-13. Transcriptional (nuclear run-on) and posttranscriptional (mRNA stability) assays confirmed that transcriptional regulation is critical for synergistic expression of CCL11. TGF-β1 plus IL-13 synergistically increased STAT-6 phosphorylation, nuclear translocation, and binding to the CCL11 promoter as compared with IL-13 alone. STAT-6 small interfering RNA significantly knocked down both STAT-6 mRNA expression and phosphorylation and inhibited CCL11 mRNA and protein expression. Regulation of the IL-4Rα complex by TGF-β1 augmented IL-13 signaling by dampening IL-13Rα2 expression, overcoming IL-13’s autoregulation of its pathway and enhancing the expression of CCL11. Our data suggest that TGF-β1 induced activation of the MEK/ERK pathway reduces IL-13Rα2 expression induced by IL-13. Thus, TGF-β1, a pleiotropic cytokine upregulated in asthmatic airways, can augment eosinophilic inflammation by interfering with IL-13’s negative feedback autoregulatory loop under MEK/ERK-dependent conditions.
Activated T Cell Exosomes Promote Tumor Invasion via Fas Signaling Pathway
Authors: Cai Zhijian , Yang Fei , Yu Lei , Yu Zhou , Jiang Lingling , Wang Qingqing , Yang Yunshan , Wang Lie , Cao Xuetao , Wang Jianli
Published: May 2012

Activated T cells release bioactive Fas ligand (FasL) in exosomes, which subsequently induce self-apoptosis of T cells. However, their potential effects on cell apoptosis in tumors are still unknown. In this study, we purified exosomes expressing FasL from activated CD8+ T cell from OT-I mice and found that activated T cell exosomes had little effect on apoptosis and proliferation of tumor cells but promoted the invasion of B16 and 3LL cancer cells in vitro via the Fas/FasL pathway. Activated T cell exosomes increased the amount of cellular FLICE inhibitory proteins and subsequently activated the ERK and NF-κB pathways, which subsequently increased MMP9 expression in the B16 murine melanoma cells. In a tumor-invasive model in vivo, we observed that the activated T cell exosomes promoted the migration of B16 tumor cells to lung. Interestingly, pretreatment with FasL mAb significantly reduced the migration of B16 tumor cells to lung. Furthermore, CD8 and FasL double-positive exosomes from tumor mice, but not normal mice, also increased the expression of MMP9 and promoted the invasive ability of B16 murine melanoma and 3LL lung cancer cells. In conclusion, our results indicate that activated T cell exosomes promote melanoma and lung cancer cell metastasis by increasing the expression of MMP9 via Fas signaling, revealing a new mechanism of tumor immune escape.
Urban organic aerosols measured by single particle mass spectrometry in the megacity of London
Authors: Dall'Osto M. , Harrison R. M.
Published: May 2012

Abstract. During the month of October 2006, as part of the REPARTEE-I experiment (Regent's Park and Tower Environmental Experiment) an Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed at an urban background location in the city of London, UK. Fifteen particle types were classified, some of which were already discussed (Dall'Osto et al., 2009a,b; Harrison et al., 2012). In this manuscript the origins and properties of four unreported particle types postulated to be due to locally generated aerosols, independent of the air mass type advected into London, are examined. One particle type, originating from lubricating oil (referred to as Ca-EC), was associated with morning rush hour traffic emissions. A second particle type, composed of both inorganic and organic species (called Na-EC-OC), was found enhanced in particle number concentration during evening time periods, and is likely to originate from a source operating at this time of day, or more probably from condensation of semi-volatile species. A third class, internally mixed with organic carbon and sulphate (called OC), was found to spike both in the morning and evenings although it could not unambiguously associated with a specific source or atmospheric process. The fourth class (Secondary Organic Aerosols – Polycyclic Aromatic Hydrocarbon; SOA-PAH) exhibited maximum frequency during the warmest part of the day, and a number of factors point towards secondary aerosol production from traffic-related volatile aromatic compounds. Single particle mass spectra of this particle type showed an oxidized polycyclic aromatic compound signature. A comparison of ATOFMS particle class data is then made with factors obtained by Positive Matrix Factorization and PAH signatures obtained from Aerosol Mass Spectrometer (AMS) data (Allan et al., 2010). Both the Ca-EC and OC particle types correlate with primary Hydrocarbon-like Organic Aerosol (HOA, R2 = 0.65 and 0.50 respectively), and Na-EC-OC correlates weakly with the AMS secondary Oxygenated Organic Aerosol (OOA), (R2 = 0.35). Cluster SOA-PAH was found not to correlate with any AMS signal. A detailed analysis was conducted to identify ATOFMS particle type(s) representative of the AMS cooking aerosol factor (COA), but no convincing associations were found. The combined ATOFMS and AMS results of this REPARTEE study do not always provide an entirely coherent interpretation.
TRANC – a novel fast-response converter to measure total reactive atmospheric nitrogen
Authors: Marx O. , Brümmer C. , Ammann C. , Wolff V. , Freibauer A.
Published: May 2012

Abstract. The input and loss of plant available nitrogen (reactive nitrogen: Nr) from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter), which offers the opportunity to quantify the sum of all airborne reactive nitrogen compounds (∑Nr) in high time resolution. The basic concept of the TRANC is the full conversion of all Nr to nitrogen monoxide (NO) within two reaction steps. Initially, reduced Nr compounds are being oxidised, and oxidised Nr compounds are thermally converted to lower oxidation states. Particulate Nr is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher nitrogen oxides or those generated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD) for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3−, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in ∑Nr concentrations and also matches the sum of all individual Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic conversions to NO occur. This assures a short residence time of the sample air inside the instrument, and minimises wall sorption problems of water soluble compounds. The fast response time (e-folding times of 0.30 to 0.35 s were found during concentration step changes) and high accuracy in capturing the dominant Nr species enables the converter to be used in an eddy covariance setup. Although a source attribution of specific Nr compounds is not possible, the TRANC is a new reliable tool for permanent measurements of the net ∑Nr flux between ecosystem and atmosphere at a relatively low maintenance and reasonable cost level allowing for diurnal, seasonal and annual investigations.
A combustion setup to precisely reference δ13C and δ2H isotope ratios of pure CH4 to produce isotope reference gases of δ13C-CH4 in synthetic air
Authors: Sperlich P. , Guillevic M. , Buizert C. , Jenk T. M. , Sapart C. J. , Schaefer H. , Blunier T.
Published: May 2012

Abstract. Isotope records of atmospheric CH4 can be used to infer changes in the biochemistry of CH4. One factor limiting quantitative estimates of changes in the biogeochemistry of CH4 are the uncertainties of the isotope measurements due to the lack of a unique isotope reference gas, certified for δ13C-CH4 or δ2H-CH4. We present a method to produce isotope reference gases for CH4 in synthetic airs that are precisely anchored to the VPDB and VSMOW scale and contain δ13C-CH4 values typical for the modern and glacial atmosphere. We quantitatively combusted two pure CH4 gases from fossil and biogenic sources and determined the δ13C and δ2H values of the produced CO2 and H2O relative to the VPDB and VSMOW scale within a very small analytical uncertainty of 0.04‰ and 0.7‰, respectively. We found isotope ratios of −39.56‰ and −56.37‰ for δ13C and −170.1‰ and −317.4‰ for δ2H in the fossil and biogenic CH4, respectively. We used both CH4 types as parental gases from which we mixed two filial CH4 gases. Their δ13C was determined to be −42.21‰ and −47.25‰, representing glacial and present atmospheric δ13C-CH4. The δ2H isotope ratios of the filial CH4 gases were found with −193.1‰ and −237.1‰, respectively. Next, we mixed aliquots of the filial CH4 gases with ultrapure N2/O2 (CH4 ≤ 2 ppb) producing two isotope reference gases of synthetic air with CH4 mixing ratios near atmospheric values. We show that our method is reproducible and does not introduce isotopic fractionation for δ13C within the uncertainties of our detection limit (we cannot conclude this for δ2H because our system is currently not prepared for δ2H-CH4 measurements in air samples). The general principle of our method can be applied to produce synthetic isotope reference gases targeting δ2H-CH4 or other gas species.
Denitrification and inference of nitrogen sources in the karstic Floridan Aquifer
Authors: Heffernan J. B. , Albertin A. R. , Fork M. L. , Katz B. G. , Cohen M. J.
Published: May 2012

Abstract. Aquifer denitrification is among the most poorly constrained fluxes in global and regional nitrogen budgets. The few direct measurements of denitrification in groundwaters provide limited information about its spatial and temporal variability, particularly at the scale of whole aquifers. Uncertainty in estimates of denitrification may also lead to underestimates of its effect on isotopic signatures of inorganic N, and thereby confound the inference of N source from these data. In this study, our objectives are to quantify the magnitude and variability of denitrification in the Upper Floridan Aquifer (UFA) and evaluate its effect on N isotopic signatures at the regional scale. Using dual noble gas tracers (Ne, Ar) to generate physical predictions of N2 gas concentrations for 112 observations from 61 UFA springs, we show that excess (i.e. denitrification-derived) N2 is highly variable in space and inversely correlated with dissolved oxygen (O2). Negative relationships between O2 and δ15NNO3 across a larger dataset of 113 springs, well-constrained isotopic fractionation coefficients, and strong 15N:18O covariation further support inferences of denitrification in this uniquely organic-matter-poor system. Despite relatively low average rates, denitrification accounted for 32 % of estimated aquifer N inputs across all sampled UFA springs. Back-calculations of source δ15NNO3 based on denitrification progression suggest that isotopically-enriched nitrate (NO3–) in many springs of the UFA reflects groundwater denitrification rather than urban- or animal-derived inputs.
Simulations over South Asia using the Weather Research and Forecasting model with Chemistry (WRF-Chem): chemistry evaluation and initial results
Authors: Kumar R. , Naja M. , Pfister G. G. , Barth M. C. , Wiedinmyer C. , Brasseur G. P.
Published: May 2012

Abstract. This study presents annual simulations of tropospheric ozone and related species made for the first time using the WRF-Chem model over South Asia for the year 2008. The model-simulated ozone, CO, and NOx are evaluated against ground-based, balloon-borne and satellite-borne (TES, OMI and MOPITT) observations. The comparison of model results with surface ozone observations from seven sites and CO and NOx observations from three sites indicate the model's ability in reproducing seasonal variations of ozone and CO, but show some differences in NOx. The modeled vertical ozone distribution agrees well with the ozone soundings data from two Indian sites. The vertical distributions of TES ozone and MOPITT CO are generally well reproduced, but the model underestimates TES ozone, OMI tropospheric column NO2 and MOPITT total column CO retrievals during all the months, except MOPITT retrievals during August–January and OMI retrievals during winter. Largest differences between modeled and satellite-retrieved quantities are found during spring when intense biomass burning activity occurs in this region. The evaluation results indicate large uncertainties in anthropogenic and biomass burning emission estimates, especially for NOx. The model results indicate clear regional differences in the seasonality of surface ozone over South Asia, with estimated net ozone production during daytime (1130–1530 h) over inland regions of 0–5 ppbv h−1 during all seasons and of 0–2 ppbv h−1 over marine regions during outflow periods. The model results indicate that ozone production in this region is mostly NOx-limited. This study shows that WRF-Chem model captures many important features of the observations and gives confidence to using the model for understanding the spatio-temporal variability of ozone over South Asia. However, improvements of South Asian emission inventories and simulations at finer model resolution, especially over the complex Himalayan terrain in northern India, are also essential for accurately simulating ozone in this region.
Spatial horizontal correlation characteristics in the land data assimilation of soil moisture
Authors: Han X. , Li X. , Hendricks Franssen H. J. , Vereecken H. , Montzka C.
Published: May 2012

Abstract. Remote sensing images deliver important information about soil moisture, but often cover only part of an area, for example due to the presence of clouds or vegetation. This paper examines the potential of incorporating the spatial horizontal correlation characteristics of surface soil moisture observations in land data assimilation in order to obtain improved estimates of soil moisture at uncovered grid cells (i.e. grid cells without observations). Observing system simulation experiments were carried out to assimilate the synthetic surface soil moisture observations into the Community Land Model for the Babaohe River Basin in northwestern China. The estimation of soil moisture at the uncovered grid cells was improved when information about surrounding observations and their spatial correlation structure was included. Including an increasing number of observations for covered and uncovered grid cells in the assimilation procedure led to a better prediction of soil moisture with an upper limit of five observations. A further increase of the number of observations did not further improve the results for this specific case. High observational coverage resulted in a better assimilation performance, depending also on the spatial distribution of observation data. In summary, the spatial horizontal correlation structure of soil moisture was found to be helpful for improving the surface soil moisture data characterization, especially for uncovered grid cells.
Associations of the Burden of Coal Abandoned Mine Lands with Three Dimensions of Community Context in Pennsylvania
Authors: Liu Ann Y. , Curriero Frank C. , Glass Thomas A. , Stewart Walter F. , Schwartz Brian S.
Published: May 2012

Background. Pennsylvania, with thousands of abandoned coal mines and miles of streams polluted with acid mine drainage, has the largest domestic coal mining burden contributing to deterioration of communities. Objectives. To evaluate contextual aspects by examining associations between coal abandoned mine lands (AML) and community measures of socioeconomic deprivation, social disorganization, and physical disorder. Methods. AML exposure data from the Reclaimed Abandoned Mine Land Inventory System were used to create density, diversity, accessibility, and clustering metrics. The three community context outcome measures were comprised of 14 census variables. In community-level analyses, 10 AML variables were evaluated separately with each dimension of community context, adjusting for covariates, in communities with and without abandoned mines. Results. We observed consistent associations between higher AML burden and worse socioeconomic deprivation, negative relations with social disorganization, but no statistically significant associations with physical disorder. Six of 10 AML variables were associated with socioeconomic deprivation, many consistently exhibiting exposure-effect patterns of worse deprivation with greater AML. Conclusions. Higher AML was associated with higher socioeconomic deprivation. These results can help prioritize the use of Surface Mining Control and Reclamation Act funds and inform decisions regarding Marcellus shale drilling to prevent analogous environmental degradation and public health impacts.