bluuebunny/crossref_metadata_2025 huggingface dataset:
Incorporation of CO2 Into Various Terminal and Internal Epoxides
Authors: Meissner Albrecht , Scholz Peter , Ondruschka Bernd
Published: February 2008

Carbon dioxide was incorporated into various oxirane-containing compounds. The starting materials include natural products with epoxy groups (1-4), glycidyl compounds (5-9) and epoxidized polymers (9, 10). It could be shown that the crosslinking side reaction is not significant for internal epoxides but important for terminal glycidyl compounds.
A gaze-based study for investigating the perception of visual realism in simulated scenes
Authors: Elhelw Mohamed , Nicolaou Marios , Chung Adrian , Yang Guang-Zhong , Atkins M. Stella
Published: February 2008

Visual realism has been a major objective of computer graphics since the inception of the field. However, the perception of visual realism is not a well-understood process and is usually attributed to a combination of visual cues and image features that are difficult to define or measure. For highly complex images, the problem is even more involved. The purpose of this paper is to present a study based on eye tracking for investigating the perception of visual realism of static images with different visual qualities. The eye-fixation clusters helped to define salient image features corresponding to 3D surface details and light transfer properties that attract observers' attention. This enabled the definition and categorization of image attributes affecting the perception of photorealism. The dynamics of the visual behavior of different observer groups were examined by analyzing saccadic eye movements. We also demonstrated how the different image categories used in the experiments were perceived with varying degrees of visual realism. The results presented can be used as a basis for investigating the impact of individual image features on the perception of visual realism. This study suggests that post-recall or simple abstraction of visual experience is not accurate and the use of eye tracking provides an effective way of determining relevant features that affect visual realism, thus allowing for improved rendering techniques that target these features.
Dynamic access-control policies on XML encrypted data
Authors: Bouganim Luc , Ngoc Francois Dang , Pucheral Philippe
Published: February 2008

The erosion of trust put in traditional database servers and in Database Service Providers and the growing interest for different forms of selective data dissemination are different factors that lead to move the access-control from servers to clients. Different data encryption and key dissemination schemes have been proposed to serve this purpose. By compiling the access-control rules into the encryption process, all these methods suffer from a static way of sharing data. With the emergence of hardware security elements on client devices, more dynamic client-based access-control schemes can be devised. This paper proposes a tamper-resistant client-based XML access-right controller supporting flexible and dynamic access-control policies. The access-control engine is embedded in a hardware-secure device and, therefore, must cope with specific hardware resources. This engine benefits from a dedicated index to quickly converge toward the authorized parts of a potentially streaming XML document. Pending situations (i.e., where data delivery is conditioned by predicates, which apply to values encountered afterward in the document stream) are handled gracefully, skipping, whenever possible the pending elements and reassembling relevant parts when the pending situation is solved. Additional security mechanisms guarantee that (1) the input document is protected from any form of tampering and (2) no forbidden information can be gained by replay attacks on different versions of the XML document and of the access-control rules. Performance measurements on synthetic and real datasets demonstrate the effectiveness of the approach. Finally, the paper reports on two experiments conducted with a prototype running on a secured hardware platform.
Proactive displays
Authors: McDonald David W. , McCarthy Joseph F. , Soroczak Suzanne , Nguyen David H. , Rashid Al M.
Published: February 2008

Academic conferences provide a social space for people to present their work and interact with one another. However, opportunities for interaction are unevenly distributed among the attendees. We seek to extend the opportunities for interaction among attendees by using technology to enable them to reveal information about their background and interests in different settings. We evaluate a suite of applications that augment three physical social spaces at an academic conference. The applications were designed to augment formal conference paper sessions and informal breaks. A mixture of qualitative observation and survey response data are used to frame the impacts from both individual and group perspectives. Respondents reported on their interactions and serendipitous findings of shared interests with other attendees. However, some respondents also identify distracting aspects of the augmentation. Our discussion relates these results to existing theory of group behavior in public places and how these social space augmentations relate to awareness as well as the problem of shared interaction models.
Subjunctive interfaces
Authors: Lunzer Aran , Hornbæk Kasper
Published: February 2008

Many applications require exploration of alternative scenarios; most support it poorly. Subjunctive interfaces provide mechanisms for the parallel setup, viewing and control of scenarios, aiming to support users' thinking about and interaction with their choices. We illustrate how applications for information access, real-time simulation, and document design may be extended with these mechanisms. To investigate the usability of this form of extension, we compare a simple census browser against a version with a subjunctive interface. In the first of three studies, subjects reported higher satisfaction with the subjunctive interface, and relied less on interim marks on paper. No reduction in task completion time was found, however, mainly because some subjects encountered problems in setting up and controlling scenarios. At the end of a second, five-session study, users of a redesigned interface completed tasks 27% more quickly than with the simple interface. In the third study we examined how subjects reasoned about multiple-scenario setups in pursuing complex, open-ended data explorations. Our main observation was that subjects treated scenarios as information holders, using them creatively in various ways to facilitate task completion.
Algorithm 871
Authors: Schreppers Walter , Cuyt Annie
Published: February 2008

In the past decade a number of libraries for multiprecision floating-point arithmetic have been developed. We describe an easy to use, generic C/C++ transcription program or precompiler for the conversion of C or C++ source code into new code that uses a C++ multiprecision library of choice. The precompiler can convert any type in the input source code to another type in the output source code. The input source can be either C or C++ , while the output code generated by the precompiler and using the new types, is C++. The type conversion is based on a simple XML configuration file which is provided by either the developer of the multiprecision library or by the user of the precompiler. The precompiler can also convert to data types with additional features, which are not supported in the types of the source code. Applicability of the precompiler is shown with the successful conversion of large subsets of the GNU Scientific Library and Numerical Recipes.
A model for computing and energy dissipation of molecular QCA devices and circuits
Authors: Ma Xiaojun , Huang Jing , Lombardi Fabrizio
Published: February 2008

Quantum-dot Cellular Automata is an emerging technology that offers significant improvements over CMOS. Recently QCA has been advocated as a technology for implementing reversible computing. However, existing tools for QCA design and evaluation have limited capabilities. This paper presents a new mechanical-based model for computing in QCA. By avoiding a full quantum-thermodynamical calculation, it offers a classical view of the principles of QCA operation and can be used in evaluating energy dissipation for reversible computing. The proposed model is mechanically based and is applicable to six-dot (neutrally charged) QCA cells for molecular implementation. The mechanical model consists of a sleeve of changing shape; four electrically charged balls are connected by a stick that rotates around an axle in the sleeve. The sleeve acts as a clocking unit, while the angular position of the stick within the changing shape of the sleeve, identifies the phase for quasi-adiabatic switching. A thermodynamic analysis of the proposed model is presented. The behaviors of various QCA basic devices and circuits are analyzed using the proposed model. It is shown that the proposed model is capable of evaluating the energy consumption for reversible computing at device and circuit levels for molecular QCA implementation. As applicable to QCA, two clocking schemes are also analyzed for energy dissipation and performance (in terms of number of clocking zones).
Exploiting virtual registers to reduce pressure on real registers
Authors: Yan Jun , Zhang Wei
Published: February 2008

It is well known that a large fraction of variables are short-lived. This paper proposes a novel approach to exploiting this fact to reduce the register pressure for pipelined processors with data-forwarding network. The idea is that the compiler can allocate virtual registers (i.e., place holders to identify dependences among instructions) to short-lived variables, which do not need to be stored to physical storage locations. As a result, real registers (i.e., physically existed registers) can be reserved for long-lived variables for mitigating the register pressure and decreasing the register spills, leading to performance improvement. In this paper, we develop the architectural and compiler support for exploiting virtual registers for statically scheduled processors. Our experimental results show that virtual registers are very effective at reducing the register spills, which, in many cases, can achieve the performance close to the processor with twice number of real registers. Our results also indicate that, for some applications, using 24 virtual, in addition to 8 real registers, can attain even higher performance than that of 16 real without any virtual registers.
Reducing cache misses through programmable decoders
Authors: Zhang Chuanjun
Published: February 2008

Level-one caches normally reside on a processor's critical path, which determines clock frequency. Therefore, fast access to level-one cache is important. Direct-mapped caches exhibit faster access time, but poor hit rates, compared with same sized set-associative caches because of nonuniform accesses to the cache sets. The nonuniform accesses generate more cache misses in some sets, while other sets are underutilized. We propose to increase the decoder length and, hence, reduce the accesses to heavily used sets without dynamically detecting the cache set usage information. We increase the access to the underutilized cache sets by incorporating a replacement policy into the cache design using programmable decoders. On average, the proposed techniques achieve as low a miss rate as a traditional 4-way cache on all 26 SPEC2K benchmarks for the instruction and data caches, respectively. This translates into an average IPC improvement of 21.5 and 42.4% for SPEC2K integer and floating-point benchmarks, respectively. The
B-Cache
consumes 10.5% more power per access, but exhibits a 12% total memory access-related energy savings as a result of the miss rate reductions, and, hence, the reduction to applications' execution time. Compared with previous techniques that aim at reducing the miss rate of direct-mapped caches, our technique requires only one cycle to access all cache hits and has the same access time of a direct-mapped cache.
Improving Speech Recognition and Understanding using Error-Corrective Reranking
Authors: Jeong Minwoo , Lee Gary Geunbae
Published: February 2008

The main issues of practical spoken-language applications for
human-computer interface are how to overcome speech recognition
errors and guarantee the reasonable end-performance of
spoken-language applications. Therefore, handling the erroneously
recognized outputs is a key in developing robust spoken-language
systems. To address this problem, we present a method to improve
the accuracy of speech recognition and performance of
spoken-language applications. The proposed error corrective
reranking approach exploits recognition environment characteristics
and domain-specific semantic information to provide robustness and
adaptability for a spoken-language system. We demonstrate some
experiments of spoken dialogue tasks and empirical results that
show an improvement in accuracy for both speech recognition and
spoken-language understanding. In our experiment, we show an error
reduction of up to 9.7% and 16.8%; of word error rate, and 5.5% and
7.9% of understanding error for the air travel and telebanking
service domains.
Web 2.0 and the semantic web: hindrance or opportunity?
Authors: Yesilada Yeliz , Harper Simon
Published: February 2008

The World Wide Web (Web) is in transition; a fundamental evolution of the model which underpins the traditional Web. This new Web, Web 2.0, is a mesh of enhanced semantics, push application widgets, and embedded scripting languages and was developed to pursue the promise of enhanced interactivity. The possible benefits of Web 2.0 are great, but it seems that without timely and prompt action disabled users will be barred from these benefits. Indeed, using sites such as: Flicker, YouTube, MySpace, Google Maps, and Google Portal will rapidly become 'offlimits' to disabled users. Semantic Web technologies have already shown themselves to be useful in addressing some issues of Web Accessibility. However, this new technology has not yet started to make its way into mainstream applications. Without change, will the benefits of the Semantic Web be lost? Will the promising enhanced interactivity of Web 2.0 technologies become increasingly inaccessible to disabled users? We pose the question:

"Web 2.0 and the Semantic Web: Hindrance or Opportunity?"

The conference was held on Monday the 7th and Tuesday the 8th of May 2007 at the Fairmont Banff Springs Hotel in Banff National Park. We welcomed 65 attendees pursuing research on Web accessibility. We accepted 40.3% of all submissions, each paper was peer reviewed by the three of our programme committee. In brief, the conference proceedings brought together a cross section of Web design, engineering and Web accessibility research. The papers included report on developments on the Web 2.0 and Semantic Web, discussed the issues regarding the evolvement of the Web, and suggested cross-pollinated solutions. Comments from our attendees suggested that they enjoyed the conference and would be participating again next year. Our social programme also attracted almost all of our delegates, which was a great fun. Overall we judge the conference to be a great success.
Accessibility research in Malaysia
Authors: Hassan Hasni , Jomhari Nazean , Hishyam Syariffanor
Published: February 2008

In recent days, there is a tendency in Malaysia that more and more people are interested the research regarding the use of computing and information technology by the ageing population and people with disabilities. Below are some examples of these projects.
Introduction
Authors: Da Silva Dilma , Wisniewski Robert W.
Published: February 2008

IBM researchers work at the frontiers of a wide range of areas. Many have very distinguished careers. IBM Research has had five Nobel Laureates and six Turing Award winners, including the latest (and first woman ever), Fran Allen. IBM has eight inductees into the National Inventors Hall of Fame and has led the world in patents for the past 14 years. Seminal innovations include Fortran, DRAM, RISC, and relational databases, to name a few. The research agenda is diverse, spanning behavioral science, chemistry, computer science, electrical engineering, materials science, mathematical sciences, biological sciences, physics, and service science. This diversity is organized into four main areas: Services, Software, Systems, and Technology. Three thousand researchers world wide are employed at labs located near Austin (Texas), Beijing, Delhi, Haifa, San Jose (California), Tokyo, Yorktown Heights (New York), and Zurich. The labs also host many visiting professors and post-doctoral researchers. IBM Research benefits from the energy and enthusiasm of a large number of student interns (more than 400 this past summer in the US labs) who bring a fresh perspective to our initiatives and strengthen our ties with academia.
End-to-end performance of commercial applications in the face of changing hardware
Authors: Jann Joefon , Burugula R. Sarma , Dubey Niteesh , Pattnaik Pratap
Published: February 2008

This paper investigates the changes in AIX behavior, or the lack of them, and the resulting performance impact from a generational change in servers in a typical large scale eCommerce application environment without extensive tuning of the OS and the application stack for the changing hardware. We have investigated the performance and impediments to performance at the microprocessor level and at the OS level. This paper dissects the performance data as observed from the OS and from hardware performance counters, and suggests areas for further improvements.
Do commodity SMT processors need more OS research?
Authors: Ruan Yaoping , Pai Vivek S. , Nahum Erich , Tracey John M.
Published: February 2008

The availability of Simultaneous Multithreading (SMT) in commodity processors such as the Pentium 4 (P4) has raised interest among OS researchers. While earlier simulation studies of SMT suggested exciting performance potential, observed improvement on the P4 has been much more restrained, raising the hope that OS research can help bridge the gap. We argue that OS research for current commodity Simultaneous Multithreading (SMT) processors is unlikely to yield significant benefits. In general, we find that SMT processor simulations were optimistic about cache and memory performance characteristics, while overlooking the OS overheads of SMT kernels versus uniprocessor kernels. Using measurement and analysis on actual hardware, we find that little opportunity exists for realistic performance gains on commodity SMT beyond what is currently achieved.
A distributed job scheduling and flow management system
Authors: Bobroff Norman , Dasgupta Gargi , Fong Liana , Liu Yanbin , Viswanathan Balaji , Benedetti Fabio , Wagner Jonathan
Published: February 2008

Grid computing, as a specific model of distributed systems, has sparked recent interest in managing job execution among distributed resource domains. Introduction of the meta-scheduler is a key feature in grid evolution, and the next step is to achieve collaborative interactions between meta-schedulers within and external to organizational boundaries to achieve scalability, balanced resource utilization, and location transparency to job submitters. This paper details a distributed system design that consists of a collaborative meta-scheduling framework, and an expanded resource model with schedulers and data as resources. With this framework, we also explore job scheduling and data management issues, and investigate job flow and meta-scheduling interactions for new applications that require job execution beyond simple sequential and conditional control.
Partition-based heap memory management in an application server
Authors: Liu Tiancheng , Li Ying , Schofield Andrew , Hogstrom Matt , Sun Kewei , Chen Ying
Published: February 2008

Heap is an important shared resource in Java virtual machine. A problem with memory management in one component can affect the whole system and even result in crashing the virtual machine. In this paper, we propose an partition-based approach to manage heap in an application server. In our approach, the shared heap is divided into logical partitions, in which instances of application components and server components are allocated separately.
MIRAGE
Authors: Gupta Karan , Sarkar Prasenjit , Mbogo Lesley
Published: February 2008

This paper presents MIRAGE, an architecture for data center storage provisioning that takes the approach of maintaining storage services for applications by ensuring well-balanced utilizations in all internal components of the storage infrastructure. We implemented MIRAGE on our local storage infrastructure and observed the sensitivity of the MIRAGE load-balancing algorithm to a combination of performance and heterogeneity skews. We also evaluated MIRAGE by deploying it on a financial data center. We reduced the service times of resource-constrained storage pools by an average of 68%.
1st Annual Haifa Systems and Storage Conference (SYSTOR 2007)
Authors: Ben-Yehuda Muli
Published: February 2008

On October 29--30, 2007, the 1st Annual Haifa Systems and Storage Conference took place at Haifa, Israel. The conference, affectionately known as SYSTOR 2007, was hosted by IBM's Haifa Labs and the Technion---Israel Institute of Technology. It was the first high-quality refereed systems and storage conference organized by IBM Haifa Labs, drawing upon the successful foundation of previous systems and storage seminars. The purpose of this conference was to forge and nourish research and working relations within the academic and industrial community in Israel and in the world, targeting researchers and practitioners alike.
Probe-Aided MulTCP
Authors: Kuo Fang-Chun , Fu Xiaoming
Published: February 2008

An aggregate congestion control mechanism, namely Probe-Aided MulTCP (PA-MulTCP), is proposed in this paper. It is based on MulTCP,a proposal for enabling an aggregate to emulate the behavior of multiple concurrent TCP connections. The objective of PA-MulTCP is to ensure the fair sharing of the bottleneck bandwidth between the aggregate and other TCP or TCP-friendly flows while keeping lightweightness and responsiveness. Unlike MulTCP, there are two congestion window loops in PA-MulTCP, namely the probe window loop and the adjusting window loop.The probe window loop constantly probes the congestion situation and the adjusting window loop dynamically adjusts the congestion window size for the arriving and departing flows within the aggregate

Our simulations demonstrate that PA-MulTCP is more stable and fairer than MulTCP over a wide range of the weight N in steady conditions as well as in varying congestion conditions. PA-MulTCP is also responsive to flow arrival/departure and thus reduces the latency of short-lived transfers. Furthermore, PA-MulTCP is lightweight, since it enjoys above advantages at the cost of only an extra probe window loop, which has a marginal influence on the implementation complexity. Finally, the design of PA-MulTCP decouples the congestion management from the other functionalities in the aggregate flow management. As a result, PA-MulTCP could be potentially applied to a wider range of scenarios, e.g. wireless TCP proxies, edge-to-edge overlays, QoS provisioning and mass data transport. TCP, Fairness, Congestion Control, Aggregate Flow Management
What would Darwin think about clean-slate architectures?
Authors: Dovrolis Constantine
Published: February 2008

As significant resources are directed towards clean-slate networking research, it is imperative to understand how clean-slate architectural research compares to the diametrically opposite paradigm of evolutionary research. This paper approaches the "evolution versus clean-slate" debate through a biological metaphor. We argue that evolutionary research can lead to less costly (more competitive) and more robust designs than clean-slate architectural research. We also argue that the Internet architecture is not ossified, as recently claimed, but that its core protocols play the role of "evolutionary kernels", meaning that they are conserved so that complexity and diversity can emerge at the lower and higher layers. We then discuss the factors that determine the deployment of new architectures or protocols, and argue, based on the notion of "auto-catalytic sets", that successful innovations are those that become synergistic components in closed loops of existing modules. The paper closes emphasizing the role of evolutionary Internet research
WebClass
Authors: Ringberg Haakon , Soule Augustin , Rexford Jennifer
Published: February 2008

Despite the flurry of anomaly-detection papers in recent years, effective ways to validate and compare proposed solutions have remained elusive. We argue that evaluating anomaly detectors on manually labeled traces is both important and unavoidable. In particular, it is important to evaluate detectors on traces from operational networks because it is in this setting that the detectors must ultimately succeed. In addition, manual labeling of such traces is unavoidable because new anomalies will be identified and characterized from manual inspection long before there are realistic models for them. It is well known, however, that manual labeling is slow and error-prone. In order to mitigate these challenges, we present WebClass, a web-based infrastructure that adds rigor to the manual labeling process. WebClass allows researchers to share, inspect, and label traffic time-series through a common graphical user interface. We are releasing WebClass to the research community in the hope that it will foster greater collaboration in creating labeled traces and that the traces will be of higher quality because the entire community has access to all the information that led to a given label
Operational comparison of available bandwidth estimation tools
Authors: Urvoy-Keller Guillaume , En-Najjary Taoufik , Sorniotti Alessandro
Published: February 2008

The available bandwidth of a path directly impacts the performance of throughput sensitive applications, e.g., p2p content replication or podcasting. Several tools have been devised to estimate the available bandwidth. The vast majority of these tools follow either the Probe Rate Model (PRM) or the Probe Gap Model (PGM).

Lao et al. [6] and Liu et al. [7] have identified biases in the PGM approach that lead to consistent underestimations of the available bandwidth. Those results were obtained under the ideal assumption of stationary cross traffic.

In this note, we confirm the existence of these biases experimentally, i.e., for the case of non stationary cross traffic. To do so, we compare one representative of the PRM family, namely Pathload, and one representative of the PGM family, namely Spruce, using long term (several day long) traces collected on an example path.

We first propose a methodology to compare operational results of two available bandwidth measurement tools. Based on the sanitized data obtained using the previous methodology, we next show that the biases identified by previous works are clearly observable on the long term, even with non stationary cross traffic. We further uncover the formal link that exists between the work by Liu et al. and the one by Lao et al.
The need for simulation in evaluating anomaly detectors
Authors: Ringberg Haakon , Roughan Matthew , Rexford Jennifer
Published: February 2008

Anomalous events that affect the performance of networks are a fact of life. It is therefore not surprising that recent years have seen an explosion in research on network anomaly detection. What is quite surprising, however, is the lack of controlled evaluation of these detectors. In this paper we argue that there are numerous important questions regarding the effectiveness of anomaly detectors that cannot be answered by the evaluation techniques employed today. We present four central requirements of a rigorous evaluation that can only be met by simulating both the anomaly and its surrounding environment. While simulation is necessary, it is not sufficient. We therefore present an outline of an evaluation methodology that leverages both simulation and traces from operational networks
Π machines
Authors: Syropoulos Apostolos
Published: February 2008

P systems is a model of computation inspired by the way cells live and function. A typical P system consists of nested compartments surrounded by
porous
membranes, which contain data that are transformed by transformation rules. P systems can be simulated by a distributed computing system, where each compartment of a given system is simulated by a (remote) process, each running on a different node. By adopting a more "liberal" membrane structure where compartments do not necessarily form a tree-structure but a graph-structure, we get a more general model of computation, which we call graph structured P systems. Any instance of the new model can be implemented by a network of virtual machines, called Π machines, where each machine is able to implement the functionality of any simple compartment.
Environmental influences on gender in the IT workforce
Authors: Trauth Eileen M. , Quesenberry Jeria L. , Yeo Benjamin
Published: February 2008

In an effort to better understand the under- representation of women within the IT profession, one promising line of investigation is the influence of factors in the socio-cultural environment. In order to examine this topic, we draw on data from a multi-year field study of women IT professionals in three regions of the U.S.: Massachusetts, North Carolina and Pennsylvania. We employ Trauth's (2000) conceptual framework of environmental influences on the development of a region's information economy to consider economic and cultural influences on women's recruitment and retention in the IT field. The findings reveal a range of influences and a wide variety of responses to them. The contribution of this research to theoretical understanding is twofold. First, we demonstrate that socio-cultural factors serve as both barriers to and facilitators of women's recruitment and retention in the IT profession. This suggests the need for investigations of not just women themselves, but also of the societal environments within which they grow up, live and work. Second, we demonstrate that there is not one unilateral set of environment factors that can explain women's under-representation. Rather, a combination of differing regional influences and individual responses to them is in evidence. This finding of variability both among environmental influences and among women's responses to them provides empirical support for ongoing theory development efforts regarding the role of individual differences in explaining women's under-representation in IT
Communication differences in virtual design teams
Authors: Ocker Rosalie J. , Fjermestad Jerry
Published: February 2008

This multi-method study distinguishes between four high performing and four low performing fully distributed virtual design teams, through an analysis of their asynchronous communication. Results indicate that these teams were similar in terms of the number of messages exchanged, the amount of communication devoted to aspects of design, and the amount and proportion of communication spent on team coordination, supportive commentary, and "other" topics. However, high performing teams were more verbose---they communicated more words. They also spent less time in brainstorming activities. Rather, high performing teams engaged in more critical commentary and active debate, compared to low performing teams. High performing teams conducted more in-depth discussions in the form of argumentation, as ideas were developed through an interactive debate of the pros and cons of issues. This debate resulted in the need for summaries, which served a dual role as they became intermediate steps in the process of writing the report deliverable
EC-FORC: A New Cyclic-Voltammetry Based Method for Examining Phase Transitions and Predicting Equilibrium
Authors: Abou Hamad Ibrahim , Robb Daniel T. T. , Novotny Mark A. , Rikvold Per Arne
Published: February 2008

We propose a new, cyclic-voltammetry based experimental technique that can not only differentiate between discontinuous and continuous phase transitions in an adsorbate layer, but also quite accurately recover equilibrium behavior from dynamic analysis of systems with a continuous phase transition. The Electrochemical first-order reversal curve (EC-FORC) diagram for a discontinuous phase transition (nucleation and growth), such as occurs in underpotential deposition, is characterized by a negative region, while such a region does not exist for a continuous phase transition, such as occurs in the electrosorption of Br on Ag(100). Moreover, for systems with a continuous phase transition, the minima of the individual EC-FORCs trace the equilibrium curve, even at very high scan rates. Since obtaining experimental data for the EC-FORC method would require only a simple reprogramming of the potentiostat used in conventional cyclic-voltammetry experiments, we belie ve that this method has significant potential for easy, rapid, in-situ analysis of systems undergoing electrochemical deposition.
A Novel Method for Electrically Modeling of Fuel Cell Using Frequency Response Technology: Executed on a Direct Methanol Fuel Cell
Authors: Wang Yang , Au George , Plichta Edward J. , Zheng Jim P.
Published: February 2008

In this paper, a novel semi-empirical modeling method to mathematically derive a nonlinear equivalent circuit from a special group of impedance fuel cell models is proposed. As an example, a 5-cm2 direct methanol fuel cell (DMFC) was modeled by this method. The derived equivalent circuit is composed of lumped nonlinear resistors, capacitors and an inductor. The nonlinear circuit has an impedance equivalent to the target fuel cell in various operating conditions and provides a good approximation of the static and transient behaviors of the fuel cell. The equivalent circuit fuel cell model was validated by comparing its numerical simulation results with its polarization curve and the dynamic behavior of the target DMFC. These comparisons were performed while the DMFC was operated under square current pulses with different upper and low current levels.
Moving Boundary Model for the Discharge of a LiCoO2 Electrode
Authors: Zhang Qi , White Ralph E.
Published: February 2008

A moving boundary model in a spherical LiCoO2 particle is presented to account for the diffusion controlled phase transition in LiCoO2 solid particles, and this model is incorporated into a porous electrode model for the LiCoO2 electrode. The simulation results agree well with the experimental data of a LiCoO2 electrode. A study of the flux distribution in the porous electrode shows that the phase transition phenomenon in the LiCoO2 particles has a significant effect on the flux distribution by changing the solid phase diffusion resistance in the particles.
Hybrid Electrocatalysts for Degradation Mitigation in PEFCs
Authors: Trogadas Panagiotis , Ramani V.
Published: February 2008

Pt/C/MnO2 hybrid catalysts were prepared by a wet chemical method. Rotating ring-disk electrode (RRDE) experiments were performed to estimate the amount of hydrogen peroxide (H2O2) formed during the oxygen reduction reaction (ORR) as a function of MnO2 content. Pt/C/ MnO2 (5% by weight of MnO2) hybrid electrocatalysts produced 50% less hydrogen peroxide than the baseline Pt/C electrocatalyst. The hybrid electrocatalysts were used to prepare membrane electrode assemblies that were tested at 90{degree sign}C and 50% RH at open circuit with pure hydrogen as fuel and air as the oxidant. The concentration of F- in the anode condensate over 24 hours was found to be reduced by a factor of 3-4 when Pt/C/MnO2 replaced Pt/C as the catalyst. Through cyclic voltammetry and RRDE kinetic studies, the lower ORR activity of the hybrid electrocatalysts was attributed to catalyst treatment with acid during MnO2 introduction.
Dynamic First-Principles Molecular-Scale Model for Solid Oxide Fuel Cells
Authors: Schmidt V. H.
Published: February 2008

Abstract - This model for voltage V vs. current density i characteristics applies both to the Solid Oxide Fuel Cell (SOFC) and Solid Oxide Electrolysis Cell (SOEC) modes of operation. It is based on reaction rates calculated from a molecular-scale model for the physical and chemical processes involved. An expression is obtained for i as a function of activation polarization Vact at either interface. For large applied positive or negative voltage it correctly predicts i to be based respectively on the reverse reaction or forward reaction attempt rate. In contrast, the Butler-Volmer i(Vact) expression incorrectly predicts infinite i for infinite applied voltage. The model expression for V(i) takes open- circuit emf, activation polarization, concentration polarization, and ohmic polarization into account. Its predictions agree quite well with experiment results obtained by another group.
Anode Characterization and SOFC Performance using Ni-YSZ Anodes Formed by Ni Impregnation Methods
Authors: Singh Anand , Krishnan Venkatesan
Published: February 2008

Impregnation technique has been used to load Ni on to a preformed porous anode matrix. Button cells with YSZ electrolyte and porous anode matrix (YSZ) have been fabricated by tape casting technique. Performance curves for a cell with 4.25 volume % Ni-YSZ anode, showed that power density increased with temperature and attained a maximum of 30.87mW/cm2 at 900oC, which is low when compared to conventional cells, which have more than 30 volume % Ni incorporated in them. Electrical conductivities of 155 S/cm and 14.7 S/cm were observed at 10.48 and 4.85 volume % Ni loadings respectively which are comparable to values obtained in literature on 30 Vol% NiO-YSZ prepared by ceramic mixing process. One of the reasons for low cell performance is that Ni film formed at such low loadings undergoes sintering and loses connectivity at the operational temperatures. This was revealed by temperature programmed conductivity studies. At loadings above 5%, the Ni film is stable and as such may be considered as anodes for SOFC's.
A Tantalum Oxide Electrode for Electrochemical Ozone Generation
Authors: Kaneda Kazuhiro , Kitsuka Kenta , Nowatari Yuko , Ikematsu Mineo , Iseki Masahiro , Higuchi Tohru , Hattori Takeshi , Tsukamoto Takeyo
Published: February 2008

An electrode with a tantalum oxide catalyst layer for electrochemical ozone generation was fabricated by sputtering. Its current efficiency for ozone generation is 8% at 10 mA/cm2. Its high value originates from the tantalum oxide band structure, in which the electronic transfer is possible at a high energy level.
Corrosion Products Formed on Silver and Copper Plates Exposed in a Volcanic Area
Authors: Watanabe Masamitsu , Handa Takao , Ichino Toshihiro , Kuwaki Nobuo
Published: February 2008

Corrosion products formed on silver and copper plates exposed in a volcanic area were analyzed to get a better understanding of silver and copper corrosion in harsh environments. Both Ag2S and AgCl were detected in the X-ray diffraction (XRD) patterns of silver plates exposed for either 22 or 212 days. Cuprite (Cu2O) and posnjakite (Cu4SO4(OH)6•H2O) were detected in the XRD pattern of a copper plate exposed for 22 days. Brochantite (Cu4SO4(OH)6), antlerite (Cu3SO4(OH)4), and geerite (Cu8S5) were detected as well in that of a copper plate exposed for 212 days. Surface observation revealed that the surface Corrosion products formed on silver and copper plates exposed in a volcanic area were analyzed to get a better understanding of silver and copper corrosion in harsh environments. Both silver sulfide (Ag2S) and silver chloride (AgCl) were detected in the X-ray diffraction (XRD) patterns of silver plates exposed for either 22 or 212 days. Cuprite (Cu2O) and posnjakite (Cu4SO4(OH)6•H2O) were detected in the XRD pattern of a copper plate exposed for 22 days. Brochantite (Cu4SO4(OH) 6), antlerite (Cu3SO4(OH)4), and geerite (Cu8S5) were detected as well in that of a copper plate exposed for 212 days. Surface observation revealed that the surface morphologies of silver and copper plates exposed for 212 days differed from those exposed for 22 days. Chemical state analysis by X-ray photoelectron spectroscopy showed that sulfur existed mainly as sulfide on the silver plates, while it existed mainly as sulfate on the copper plates. This agrees well with the XRD results.
Hexavalent Chromium-Free Pre-Treatment for Galvanized Steel
Authors: Hernandez Laura A. , Hernández Luis S. , Miranda J M. , Dominguez Octavio
Published: February 2008

The corrosion protection provided by an organic inhibitor containing an alkanolamine salt of a polycarboxilic acid that is suggested as non-toxic alternative to chromate and phosphate conversion coatings on galvanized steel was studied. Open circuit corrosion potential evolution, linear polarization, potentiodynamic polarization, electrochemical impedance spectroscopy, x-ray diffraction, salt spray (fog) tests and immersion - weight loss tests were used to evaluate the provided protection in a 0.5 M aerated NaCl solution. All tests gave concordant results, indicating that the chromate-free inhibitor does protect galvanized steel in this environment, even though the provided protection was less than that of the chromate conversion coating. It was observed that after a moderate initial attack, and except for the phosphated samples, the corrosion rate diminishes due to the appearance and growth of passivating corrosion products layers, mainly con stituted by zinc hydroxychloride (Zn5(OH)8Cl2•H2O) and two varieties of zinc hydroxide.
Differential relaxation and contractile responses of the human upper esophageal sphincter mediated by interplay of mucosal and deep mechanoreceptor activation
Authors: Szczesniak Michal M. , Fuentealba Sergio E. , Burnett Anthea , Cook Ian J.
Published: February 2008

Background and aims: the neural mechanisms of distension-induced esophagoupper esophageal sphincter (UES) reflexes have not been explored in humans. We investigated the modulation of these reflexes by mucosal anesthesia, acid exposure, and GABAB receptor activation. In 55 healthy human subjects, UES responses to rapid esophageal air insufflation and slow balloon distension were examined before and after pretreatment with 15 ml of topical esophageal lidocaine, esophageal HCl infusion, and baclofen 40 mg given orally. In response to rapid esophageal distension, UES can variably relax or contract. Following a mucosal blockade by topical lidocaine, the likelihood of a UES relaxation response was reduced by 11% ( P < 0.01) and the likelihood of a UES contractile response was increased by 14% ( P < 0.001) without alteration in the overall UES response rate. The UES contractile response to rapid esophageal air insufflation was also increased by 8% ( P < 0.05) following sensitization by prior mucosal acid exposure. The UES contractile response, elicited by balloon distension, was regionally dependent ( P < 0.05) (more frequent and of higher amplitude with proximal esophageal distension), and the response was attenuated by topical lidocaine ( P < 0.05). Baclofen (40 mg po) had no effect on these UES reflexes. Abrupt gaseous esophageal distension activates simultaneously both excitatory and inhibitory pathways to the UES. Partial blockade of the mucosal mechanosensitive receptors permits an enhanced UES contractile response mediated by deeper esophageal mechanoreceptors. Activation of acid-sensitive esophageal mucosal chemoreceptors upregulates the UES contractile response, suggestive of a protective mechanism.
Age-related differences in postinfarct left ventricular rupture and remodeling
Authors: Yang Yining , Ma Yitong , Han Wei , Li Jun , Xiang Yang , Liu Fen , Ma Xiang , Zhang JianFa , Fu Zhenyan , Su Yi-Dan , Du Xiao-Jun , Gao Xiao-Ming
Published: February 2008

Cardiac rupture is more prevalent in elderly patients with first onset of acute myocardial infarct (MI), but the mechanism remains unexplored. We investigated the differences in the incidence of cardiac rupture and early left ventricular (LV) remodeling following coronary artery ligation between old (12-mo) and young (3-mo) C57Bl/6 male mice and explored responsible mechanisms. The incidence of rupture within 1 wk after MI was significantly higher in old than in young mice (40.7 vs. 18.3%, P = 0.013) despite a similar infarct size in both age groups. Old mice dying of rupture had more severe infarct expansion than young counterparts. Echocardiography and catheterization at day 7 revealed more profound LV chamber dilatation and dysfunction as well as higher blood pressures in aged mice. At day 3 after MI immediately before the peak of rupture occurrence, we observed significantly higher content of type I and III collagen, a greater density of macrophage and neutrophil, and markedly enhanced mRNA expression of inflammatory cytokines in the infarcted myocardium in old than in young mice. Furthermore, a more dramatic increment of matrix metalloproteinase (MMP)-9 activity was found in old than in young infarcted hearts, in keeping with enhanced inflammatory response. Collectively, these results revealed that old mice had a higher risk of post-MI cardiac rupture despite a higher level of collagen content and cross-linking. Enhanced inflammatory response and subsequent increase in MMP-9 activity together with higher blood pressure are important factors responsible for the higher risk of cardiac rupture and more severe LV remodeling in the aged heart following acute MI.
Lysozyme, a mediator of sepsis that produces vasodilation by hydrogen peroxide signaling in an arterial preparation
Authors: Mink Steven N. , Kasian Krika , Santos Martinez Luis E. , Jacobs Hans , Bose Ratna , Cheng Zhao-Qin , Light R. Bruce
Published: February 2008

In septic shock, systemic vasodilation and myocardial depression contribute to the systemic hypotension observed. Both components can be attributed to the effects of mediators that are released as part of the inflammatory response. We previously found that lysozyme (Lzm-S), released from leukocytes, contributed to the myocardial depression that develops in a canine model of septic shock. Lzm-S binds to the endocardial endothelium, resulting in the production of nitric oxide (NO), which, in turn, activates the myocardial soluble guanylate cyclase (sGC) pathway. In the present study, we determined whether Lzm-S might also play a role in the systemic vasodilation that occurs in septic shock. In a phenylephrine-contracted canine carotid artery ring preparation, we found that both canine and human Lzm-S, at concentrations similar to those found in sepsis, produced vasorelaxation. This decrease in force could not be prevented by inhibitors of NO synthase, prostaglandin synthesis, or potassium channel inhibitors and was not dependent on the presence of the vascular endothelium. However, inhibitors of the sGC pathway prevented the vasodilatory activity of Lzm-S. In addition, Aspergillus niger catalase, which breaks down H2O2, as well as hydroxyl radical scavengers, which included hydroquinone and mannitol, prevented the effect of Lzm-S. Electrochemical sensors corroborated that Lzm-S caused H2O2 release from the carotid artery preparation. In conclusion, these results support the notion that when Lzm-S interacts with the arterial vasculature, this interaction results in the formation of H2O2, which, in turn, activates the sGC pathway to cause relaxation. Lzm-S may contribute to the vasodilation that occurs in septic shock.