bluuebunny/crossref_metadata_2025 huggingface dataset:
Why people buy virtual items in virtual worlds with real money
Authors: Guo Yue , Barnes Stuart
Published: November 2007

Virtual worlds, such as Second Life and Everquest, have grown into virtual game communities that have economic potential. In such communities, virtual items are bought and sold between individuals for real money. The study detailed in this paper aims to identify, model and test the individual determinants for the decision to purchase virtual items within virtual game communities. A comprehensive understanding of these key determinants will enable researchers to further the understanding of player behavior towards virtual item transactions, which are an important aspect of the economic system within virtual games and often raise one of the biggest challenges for game community operators. A model will be developed via a mixture of new constructs and established theories, including the theory of planned behavior (TPB), the technology acceptance model (TAM), trust theory and unified theory of acceptance and use of technology (UTAUT). For this purpose the research uses a sequential, multi-method approach in two phases: combining the use of inductive, qualitative data from focus groups and expert interviews in phase one; and deductive, quantitative survey data in phase two. The final model will hopefully provide an impetus to further research in the area of virtual game community transaction behavior. The paper rounds off with a discussion of further research challenges in this area over the next seven years.
Identity formation, learning styles and trust in virtual worlds
Authors: Junglas Iris A. , Johnson Norman A. , Steel Douglas J. , Abraham D. Chon , Loughlin Paul Mac
Published: November 2007

Avatars in virtual worlds exhibit many of the social behaviors found in real life. As such, we can learn much about our own behaviors from them based on prior theories. But social psychological theories that help researchers understand real life behaviors may not necessarily apply to virtual worlds. In fact, we know little about how human behaviors, as depicted by the actions of avatars, will be different than they are in real life. For insight into this, we look at how virtual worlds impact three behaviors: forming an identity, learning, and trusting. Each of these provides some insight into behavior in virtual worlds and suggests what we must work to understand in order to modify or adapt existing social psychological theories to apply to virtual worlds.
Lesbian, gay, bisexual and transgender (LGBT) issues in virtual worlds
Authors: Blodgett Bridget Marie , Xu Heng , Trauth Eileen M.
Published: November 2007

In virtual worlds, users interact with each other by creating virtual identities through avatars. As the avatar creation process is constrained by the assumptions of designers who develop the avatar creation tools, some potential participants in virtual worlds are forced into narrow social roles that may not accurately represent them. Drawing on structuration theory and trust literature, we develop a research agenda that addresses how avatar-based technologies and user social identities may be mutually constructed and how identity misrepresentation may impact trust in virtual worlds. This paper demonstrates the importance of a discussion of Lesbian, Gay, Bisexual and Transgender (LGBT) issues in virtual worlds. These issues require additional research that should closely examine the ongoing changes both in the technology facilitating the virtual worlds, as well as the social landscape that governs issues of diversity in general, and gender issues in particular.
SA1
Authors: Barnes John G. P.
Published: November 2007

This tutorial assumes no previous knowledge or experience with the Ada programming language.

Ada was originally designed in around 1980. Important goals included: to provide a portable and uniform language to replace a number of existing languages then in use; to capture the state of the art in language design; to recognize that programming was a serious engineering discipline; and to be highly reliable and encourage the development of long lived and maintainable programs.

However, Ada 83 (as the first version was known) was developed before the ideas of OOP matured and tasking was fully understood. Accordingly Ada was enhanced in 1995 to cover these topics and others. In this tutorial John will introduce the main themes of Ada and hopefully show why it is an excellent language for systems that need to be reliable and to be maintained.
SA2: languages for safety-critical software
Authors: Brosgol Ben
Published: November 2007

This intermediate-level tutorial is aimed at people with a technical background in software development. No previous experience with safety-critical standards is required. Some familiarity with one or more of C, C++, Ada, or Java would be useful.

Safety-critical systems (whose anomalous behavior could cause catastrophic or major failure involving loss of life) are becoming increasingly prevalent. Standards such as
DO-178B
, originally developed for commercial avionics, are attracting attention in other segments. The requirement to comply with such standards imposes constraints (on quality assurance, traceability, etc. ) much beyond what is typical for Commercial-Off-The-Shelf Software. One of the major decisions that affects safety certification is the choice of programming language(s). Specific language features, either by their presence of absence, may make certification easier or harder. (Practicalities such as tool support and programmer experience are of course also important but are outside the scope of the tutorial).

This tutorial first summarizes existing safety standards, with a focus on DO-178B, and explains how they affect the requirements on a programming language. It specifically addresses the challenges imposed by Object-Oriented Technology and summarizes the work currently underway on DO-178C. The tutorial then assesses three language technologies -- C (including C++), Ada, and Java - with respect to suitability for meeting these requirements through appropriate subsetting. MISRA C, SPARK, and the in-progress Safety-Critical Java Technology are specifically identified and reviewed.
SP2
Authors: Sward Ricky E.
Published: November 2007

This tutorial covers the principles of Service-Oriented Architectures (SOA) including loose coupling, encapsulation, reusability, composibility, etc. The attendee will learn about the Ada Web Server (AWS) and how SOA interfaces, session management, etc. are implemented using AWS. The tutorial will also cover the fundamentals of the Enterprise Service Bus (ESB), a key enabling component of the SOA. Attendees will learn about ESB endpoints, data routing, automatic translations, etc. They will also learn how to connect Ada web services to an ESB, how to expose the web services, and how to use AWS with the ESB through in-class exercises and demonstrations. The tutorial will be very interactive and attendees are encouraged to bring their laptop computers.
MF1
Authors: Chapman Rod
Published: November 2007

Practising software engineers, programme managers, and those involved with procurement of high-integrity software systems might attend this tutorial. Some background in the development of safety- or security-critical software might be useful, but not essential.

This tutorial will cover the use of "Correctness by Construction" (CbyC) techniques in the development of highly secure software systems. While the use of CbyC is well-known in the development of safety-related systems, it has also been deployed in the domain of highly secure systems. The software world seems plagued by security problems caused by basic mistakes in software design and construction, but this tutorial will show how practices from the safety-critical domain can be used to tackle these problems. In particular, the role of formal methods, programming language design, and strong static verification will be covered. The tutorial will be illustrated with reference to CbyC security projects such as the MULTOS CA and the NSA Tokeneer system.

Software security is one of the highest-profile and most important topics facing researchers today. The plague of "buffer overflow" and similar attacks that we read about every day seem almost endemic, yet these are problems that have been faced (and solved) by the safety-critical community for many years. This tutorial will recount our experience in building high-grade secure systems using the CbyC approach developed by Praxis over the last 15 years.
MA1
Authors: McCormick John W.
Published: November 2007

This tutorial assumes basic knowledge or experience with the Ada programming language.

This tutorial covers two of the major problems with parallel and real-time programming -- time management and storage management. Parallel processing, whether on single-processor machines or multiple processors, has many pitfalls. We will examine these potential pitfalls, and discuss ways to avoid common problems, such as deadlocks and race conditions. We will also discuss how to write code that efficiently passes data with other parallel processes. The basics of parallel processing are covered, leading to a discussion and examples using Ada tasking. In addition, the Ada Real-Time Systems Annex is also covered.
MP1
Authors: Singhoff Frank
Published: November 2007

This tutorial assumes basic knowledge or experience with the Ada programming language. Basic understanding of tasking and real-time constraints -- at the level of tutorial MA1 -- would be helpful. We assume that attendees have a minimal background on real time operating systems, Ada tasking and critical real time applications/systems; however, a (very) short presentation of such topics will be included in the tutorial.

This tutorial deals with real time scheduling theory and its use with Ada. Real time scheduling theory was firstly proposed in 1974, but stays mostly unused by many software designers.

Too many practitioners have no background on real time scheduling. This tutorial should help them to understand the basis of such a theory and to apply it with Ada technologies. This tutorial is expected to help Ada engineers to predict the performances of their critical Ada real time applications.

This tutorial will be organized in three parts: 1. First, we define what a real time system is and then, the theoretical results of the real time scheduling theory are presented. The basic task models and schedulers are explained (their behavior and their properties). The tutorial focusses on fixed priority scheduler and its feasibility tests (eg. Rate monotonic and worst case task response time) which is the most useful scheduler with current real-life applications. However, a dynamic priority scheduler is also presented (eg. EDF). At the end of this first part, attendees should understand what a feasibility test is and how it can help them to predict performances of their real time applications. This part is ended with a short introduction on shared resource support (eg. what a priority inversion is, how PIP/PCP work).

2. Second, we show how real time scheduling features are taken into account in Ada international standards such as ISO/IEC Ada 1995 and 2005, the POSIX 1003 Ada binding and ARINC 653 (which is an avionic operating system standard providing an Ada binding). In this part, we try to show the relationships between the real time scheduling theory and the implementation of real time schedulers into practical systems.

3. Finally, some Ada program examples are presented and explained.
Using mathematics to improve ada compiled code, part 2
Authors: Maurer Ward D.
Published: November 2007

In a previous paper, we presented a method of eliminating most procedure call overhead, and most static scoping overhead, in compiling a program written in Ada, or, for that matter, in any language which allows nested procedures. This involves the construction of a loop tree for the call graph of the program; we described this in another earlier paper. Once this is constructed, we make use of a criterion for deciding when a new base register is needed. Suppose that U and V are procedures, with V nested in U. Then the only time a new base register might be needed by V is when there is a loop, in the loop tree, that contains V but not U. This result was stated without proof in the first part of this paper; here we present the proof, after reviewing some basic mathematical concept.
AADL modeling and analysis of hierarchical schedulers
Authors: Singhoff Frank , Plantec Alain
Published: November 2007

A system based on a hierarchical scheduler is a system in which the processor is shared between several collaborative schedulers. Such schedulers exist since 1960 and they are becoming more and more investigated and proposed in real-life applications. For example, the ARINC 653 international standard which defines an Ada interface for avionic real time operating systems provides such a kind of collaborative schedulers. This article focuses on the modeling and the performance analysis of hierarchical schedulers. We investigate the modeling of hierarchical schedulers with AADL. Hierarchical scheduler timing and synchronization relationships are expressed with a domain specific language based on timed automata: the Cheddar language. With the meta CASE tool Platypus, we generate Ada packages implementing the Cheddar language. These Ada packages are part of Cheddar, a real time scheduling simulator. With these Ada packages, Cheddar is able to perform analysis by scheduling simulation of AADL systems composed of hierarchical schedulers. An AADL model of the ARINC 653 hierarchical scheduling is described as an illustration.
Verified component-based software in SPARK
Authors: Lau Kung-Kiu , Wang Zheng
Published: November 2007

SPARK is useful for developing reliable software for safety-critical systems, using the `correctness-by-construction' approach. It also has verification tools that can be used to produce verified software. To tackle larger-scale development of verified software, components are useful. In this paper we show how to define and implement software components in SPARK and use existing SPARK tools to produce verified component-based software. We demon- strate our approach on a missile guidance system.
Parallel evolution of game evaluation functions in ada
Authors: Hallmark Tyler B. , Ressler Eugene K.
Published: November 2007

This is an Ada experience report, where we conclude that Ada tasking and distributed processing facilities make it a good research tool for experimentation with algorithms that might eventually need multiple processors. We implemented a genetic algorithm in Ada to create effective computer players for Connect4. Key to our success was employing Ada tasking and ALRM Annex E Distributed computing to harness a symmetric multiproces-sor and a distributed machine with very few code changes. Easy extension of an original single-task code to multi-tasking and distributed variants-even though extension was not planned in advance-was essential to timely completion. Using either the parallel or distributed implementation, about 150 processor hours were sufficient to evolve players that neither the GNU "Four-in-a-Row" Expert player nor the author could defeat. This algorithm relies on human expertise to restrict the genetic search space. Work is in progress on a new algorithm with near-zero encoded knowledge, which will run on 220 distributed nodes within the same distributed computing framework.
Using SPARK for a beginner's course on reasoning about imperative programs
Authors: Lau Kung-Kiu
Published: November 2007

Teaching beginners predicate transformer semantics for imperative languages is not a trivial task. For Computer Science majors, the teaching of the theoretical material must be supported by suitable practical course work. For this, we need a suitable language with appropriate tool support. In this paper, we describe our experience of using SPARK and its tools for this purpose. Our experience has been a very positive one. practical work.
The compiler as a static analysis tool
Authors: Dewar Robert B. K.
Published: November 2007

This paper shows that a programming language compiler can perform many kinds of tasks that are generally viewed as the domain of separate static analysis tools and, in the other direction, identifies certain kinds of analysis that are best left to separate tools.
Towards a demonstrably-correct ada compiler
Authors: Nettleton Chris , Ifill Wilson , Marsh Colin
Published: November 2007

We report on a significant new compiler technology for applications requiring the highest level of reliability. This work is partly funded by AWE plc and takes into account previous AWE work on a demonstrably correct compiler for a Pascal-like language. This work will be of interest to anyone developing safety-critical software.

Today's Ada compilers are based on 1980s' technology, when 4M Bytes of memory was considered sufficient for a project of 10 users. Using today's computers, when even a laptop computer has 512 M Bytes of memory; we can offer a much better compiler for a fraction of the cost. Initial estimates suggest a new technology compiler will be 1/50th the number of source lines, yet meet all our requirements for features and run-time performance.

We have already confirmed the feasibility of our approach in a prototype compiler. This handles a well-defined subset of Ada95 and employs algebraic simplifications in place of optimizations. By prohibiting recursion, we avoid costly run-time organization. Our prototype run-time system is just three instructions.

Our compiler is written in a notation much like ordinary mathematics, and is therefore amenable to mathematical techniques such as theorem proving. Later we intend to offer a proof of correctness. In the meantime, we will demonstrate correctness, both in the sense that a given program has been correctly compiled, and that all programs will be correctly compiled.

The prototype compiler performs well. It compiles at several thousand lines per second and generates code that compares well with that from our optimizing compiler.
Birds-of-a-feather
Authors: Dewar Robert
Published: November 2007

This BOF will discuss future directions for the GNAT technology, including both the GAP and Pro versions. We at AdaCore will give some of our thoughts on interesting future possibilities, but mostly we would like to hear from the user community, so we see this session as an open discussion of interesting ideas for the future. This is a chance for you to say what you want, and have your ideas discussed!
Static analysis summit II
Authors: Black Paul E.
Published: November 2007

Funded by the Department of Homeland Security (DHS), the National Institute of Standards and Technology (NIST) started a long-term, ambitious project to identify, enhance and develop software assurance tools. The Software Assurance Metrics And Tool Evaluation (SAMATE) project is leading in (A) developing tests for software evaluation tools, (B) measuring the effectiveness of tools, and (C) identifying gaps in tools and methods. See the workshop web site at http://samate.nist.gov/ SASII.
VEGF and thrombin induce MKP-1 through distinct signaling pathways: role for MKP-1 in endothelial cell migration
Authors: Kinney Corttrell M. , Chandrasekharan Unni M. , Mavrakis Lori , DiCorleto Paul E.
Published: November 2007

We have previously reported that MAPK phosphatase-1 (MKP-1/CL100) is a thrombin-responsive gene in endothelial cells (ECs). We now show that VEGF is another efficacious activator of MKP-1 expression in human umbilical vein ECs. VEGF-A and VEGF-E maximally induced MKP-1 expression in ECs; however, the other VEGF subtypes had no effect. Using specific neutralizing antibodies, we determined that VEGF induced MKP-1 specifically through VEGF receptor 2 (VEGFR-2), leading to the downstream activation of JNK. The VEGF-A165isoform stimulated MKP-1 expression, whereas the VEGF-A162isoform induced the gene to a lesser extent, and the VEGF-A121isoform had no effect. Furthermore, specific blocking antibodies against neuropilins, VEGFR-2 coreceptors, blocked MKP-1 induction. A Src kinase inhibitor (PP1) completely blocked both VEGF- and thrombin-induced MKP-1 expression. A dominant negative approach revealed that Src kinase was required for VEGF-induced MKP-1 expression, whereas Fyn kinase was critical for thrombin-induced MKP-1 expression. Moreover, VEGF-induced MKP-1 expression required JNK, whereas ERK was critical for thrombin-induced MKP-1 expression. In ECs treated with short interfering (si)RNA targeting MKP-1, JNK, ERK, and p38 phosphorylation were prolonged following VEGF stimulation. An ex vivo aortic angiogenesis assay revealed a reduction in VEGF- and thrombin-induced sprout outgrowth in segments from MKP-1-null mice versus wild-type controls. MKP-1 siRNA also significantly reduced VEGF-induced EC migration using a transwell assay system. Overall, these results demonstrate distinct MAPK signaling pathways for thrombin versus VEGF induction of MKP-1 in ECs and point to the importance of MKP-1 induction in VEGF-stimulated EC migration.
Substrate specificities and activities of AZAP family Arf GAPs in vivo
Authors: Cuthbert Ellen J. , Davis Kathryn K. , Casanova James E.
Published: November 2007

The ADP-ribosylation factor (Arf) GTPases are important regulators of vesicular transport in eukaryotic cells. Like other GTPases, the Arfs require guanine nucleotide exchange factors to facilitate GTP loading and GTPase-activating proteins (GAPs) to promote GTP hydrolysis. Whereas there are only six mammalian Arfs, the human genome encodes over 20 proteins containing Arf GAP domains. A subset of these, referred to as AZAPs (Randazzo PA, Hirsch DS. Cell Signal 16: 401–413, 2004), are characterized by the presence of at least one NH2-terminal pleckstrin homology domain and two or more ankyrin repeats following the GAP domain. The substrate specificities of these proteins have been previously characterized by using in vitro assay systems. However, a limitation of such assays is that they may not accurately represent intracellular conditions, including posttranslational modifications, or subcellular compartmentalization. Here we present a systematic analysis of the GAP activity of seven AZAPs in vivo, using an assay for measurement of cellular Arf-GTP (Santy LC, Casanova JE. J Cell Biol 154: 599–610, 2001). In agreement with previous in vitro results, we found that ACAP1 and ACAP2 have robust, constitutive Arf6 GAP activity in vivo, with little activity toward Arf1. In contrast, although ARAP1 was initially reported to be an Arf1 GAP, we found that it acts primarily on Arf6 in vivo. Moreover, this activity appears to be regulated through a mechanism involving the NH2-terminal sterile-α motif. AGAP1 is unique among the AZAPs in its specificity for Arf1, and this activity is dependent on its NH2-terminal GTPase-like domain. Finally, we found that expression of AGAP1 induces a surprising reciprocal activation of Arf6, which suggests that regulatory cross talk exists among Arf isoforms.
Activation of p38 mitogen-activated protein kinase abolishes insulin-mediated myocardial protection against ischemia-reperfusion injury
Authors: Chai Weidong , Wu Yangsong , Li Guolian , Cao Wenhong , Yang Zequan , Liu Zhenqi
Published: November 2007

Myocardial ischemia-reperfusion injury contributes significantly to morbidity and mortality in patients with diabetes. Insulin decreases myocardial infarct size in animals and the rate of apoptosis in cultured cells. Ischemia-reperfusion activates p38 mitogen-activated protein kinase (MAPK), which regulates cellular apoptosis. To examine whether p38 MAPK affects insulin's cardioprotection against ischemia-reperfusion injury, we studied overnight-fasted adult male rats by use of an in vivo rat model of myocardial ischemia-reperfusion. A euglycemic clamp (3 mU·min−1·kg−1) was begun either 10 min before ischemia (InsulinBI), 5 min before reperfusion (InsulinBR), or 30 min after the onset of reperfusion (InsulinAR), and continued until the end of the study. Compared with saline control, insulin decreased the infarct size in both InsulinBI( P < 0.001) and InsulinBR( P < 0.02) rats but not in InsulinARrats. The ischemic area showed markedly increased phosphorylation of p38 MAPK compared with the nonischemic area in saline animals. Acute activation of p38 MAPK with anisomycin (2 mg/kg iv 10 min before ischemia) had no effect on infarct size in saline rats. However, it completely abolished insulin's protective effect in InsulinBIand InsulinBRrats. Activation of p38 MAPK by anisomycin was associated with marked and persistent elevation in IRS-1 serine phosphorylation. Treatment of animals with SB-239063, a potent and specific inhibitor of p38 MAPK, 10 min before reperfusion enabled insulin-mediated myocardial protection in InsulinARrats. We conclude that insulin protects myocardium against ischemia-reperfusion injury when given prior to ischemia or reperfusion, and activation of p38 MAPK abolishes insulin's cardioprotective effect.
Comparison between surrogate indexes of insulin sensitivity and resistance and hyperinsulinemic euglycemic clamp estimates in mice
Authors: Lee Sihoon , Muniyappa Ranganath , Yan Xu , Chen Hui , Yue Lilly Q. , Hong Eun-Gyoung , Kim Jason K. , Quon Michael J.
Published: November 2007

Insulin resistance contributes to the pathophysiology of diabetes, obesity, and their cardiovascular complications. Mouse models of these human diseases are useful for gaining insight into pathophysiological mechanisms. The reference standard for measuring insulin sensitivity in both humans and animals is the euglycemic glucose clamp. Many studies have compared surrogate indexes of insulin sensitivity and resistance with glucose clamp estimates in humans. However, regulation of metabolic physiology in humans and rodents differs and comparisons between surrogate indexes and the glucose clamp have not been directly evaluated in rodents previously. Therefore, in the present study, we compared glucose clamp-derived measures of insulin sensitivity (GIR and SIClamp) with surrogate indexes, including quantitative insulin-sensitivity check index (QUICKI), homeostasis model assessment (HOMA), 1/HOMA, log(HOMA), and 1/fasting insulin, using data from 87 mice with a wide range of insulin sensitivities. We evaluated simple linear correlations and performed calibration model analyses to evaluate the predictive accuracy of each surrogate. All surrogate indexes tested were modestly correlated with both GIR and SIClamp. However, a stronger correlation between body weight per se and both GIR and SIClampwas noted. Calibration analyses of surrogate indexes adjusted for body weight demonstrated improved predictive accuracy for GIR [e.g., R = 0.68, for QUICKI and log(HOMA)]. We conclude that linear correlations of surrogate indexes with clamp data and predictive accuracy of surrogate indexes in mice are not as substantial as in humans. This may reflect intrinsic differences between human and rodent physiology as well as increased technical difficulties in performing glucose clamps in mice.
Survival dependency of intramuscular ICC on vagal afferent nerves in the cat esophagus
Authors: Huizinga Jan. D. , Reed David E. , Berezin Irene , Wang Xuan-Yu , Valdez Diana. T. , Liu Louis W. C. , Diamant Nicholas E.
Published: November 2007

Interstitial cells of Cajal (ICC) have been proposed as stretch receptors for vagal afferent nerves in the stomach based on immunohistochemical studies. The aim of the present study was to use electron microscopy and the anterograde degeneration technique to investigate ultrastructural features and survival dependency of ICC associated with vagal afferent innervation of the cat esophagus. This is the first report on the ultrastructural characteristics of ICC in the cat esophagus. Intramuscular ICC (ICC-IM) were identified throughout the musculature, whereas ICC in the myenteric plexus were rare. ICC-IM were particularly numerous in septa aligned with smooth muscle bundles. They were in synapse-like contact with nerve varicosities and in gap junction contact with smooth muscle cells. Smooth muscle cells also made contact with ICC through peg and socket junctions. Precision damage through small-volume injection of saline in the center of the nodose ganglion from the lateral side, known to selectively affect sensory nerves, was followed within 24 h by degeneration of a subset of nerve varicosities associated with ICC-IM, as well as degeneration of the associated ICC-IM. Smooth muscle cells were not affected. Nerves of Auerbachs plexus and associated ICC were not affected. In summary, ICC-IM aligning the esophageal muscle bundles form specialized synapse-like contacts with vagal afferent nerves as well as gap junction and peg-and-socket contacts with smooth muscle cells. This is consistent with a role of ICC-IM as stretch receptors associated with vagal afferent nerves; the ICC-vagal nerve interaction appears essential for the survival of the ICC.
Role of CCK1 and Y2 receptors in activation of hindbrain neurons induced by intragastric administration of bitter taste receptor ligands
Authors: Hao Shuzhen , Sternini Catia , Raybould Helen E.
Published: November 2007

G-protein-coupled receptors signaling bitter taste (T2Rs) in the oral gustatory system and the α-subunit of the taste-specific G-protein gustducin are expressed in the gastrointestinal (GI) tract. α-Subunit of the taste-specific G-protein gustducin colocalizes with markers of enteroendocrine cells in human and mouse GI mucosa, including peptide YY. Activation of T2Rs increases cholecystokinin (CCK) release from the enteroendocrine cell line, STC-1. The aim of this study was to determine whether T2R agonists in the GI tract activate neurons in the nucleus of the solitary tract (NTS) and whether this activation is mediated by CCK and peptide YY acting at CCK1 and Y2 receptors. Immunocytochemistry for the protooncogene c-Fos protein, a marker for neuronal activation, was used to determine activation of neurons in the midregion of the NTS, the region where vagal afferents from the GI tract terminate. Intragastric administration of the T2R agonist denatonium benzoate (DB), or phenylthiocarbamide (PTC), or a combination of T2R agonists significantly increased the number of Fos-positive neurons in the mid-NTS; subdiaphragmatic vagotomy abolished the NTS response to the mixture of T2R agonists. Deletion of CCK1 receptor gene or blockade of CCK1 receptors with devazepide abolishes the activation of NTS neurons in response to DB, but had no effect on the response to PTC. Administration of the Y2 receptor antagonist BIIE0246 blocks the activation of NTS neurons to DB, but not PTC. These findings suggest that activation of neurons in the NTS following administration of T2R agonists to the GI tract involves CCK1 and Y2 receptors located on vagal afferent terminals in the gut wall. T2Rs may regulate GI function via release of regulatory peptides and activation of the vagal reflex pathway.
Human Superior Parietal Lobule Is Involved in Somatic Perception of Bimanual Interaction With an External Object
Authors: Naito Eiichi , Scheperjans Filip , Eickhoff Simon B. , Amunts Katrin , Roland Per E. , Zilles Karl , Ehrsson H. Henrik
Published: November 2007

The question of how the brain represents the spatial relationship between the own body and external objects is fundamental. Here we investigate the neural correlates of the somatic perception of bimanual interaction with an external object. A novel bodily illusion was used in conjunction with functional magnetic resonance imaging (fMRI). During fMRI scanning, seven blindfolded right-handed participants held a cylinder between the palms of the two hands while the tendon of the right wrist extensor muscle was vibrated. This elicited a kinesthetic illusion that the right hand was flexing and that the hand-held cylinder was shrinking from the right side. As controls, we vibrated the skin surface over the nearby bone beside the tendon or vibrated the tendon when the hands were not holding the object. Neither control condition elicited this illusion. The significance of the illusion was also confirmed in supplementary experiments outside the scanner on another 16 participants. The “bimanual shrinking-object illusion” activated anterior parts of the superior parietal lobule (SPL) bilaterally. This region has never been activated in previous studies on unimanual hand or hand-object illusion. The illusion also activated left-hemispheric brain structures including area 2 and inferior parietal lobule, an area related to illusory unimanual hand-object interaction between a vibrated hand and a touched object in our previous study. The anterior SPL seems to be involved in the somatic perception of bimanual interaction with an external object probably by computing the spatial relationship between the two hands and a hand-held object.
Decoding of Temporal Intervals From Cortical Ensemble Activity
Authors: Lebedev Mikhail A. , O'Doherty Joseph E. , Nicolelis Miguel A. L.
Published: November 2007

Neurophysiological, neuroimaging, and lesion studies point to a highly distributed processing of temporal information by cortico-basal ganglia-thalamic networks. However, there are virtually no experimental data on the encoding of behavioral time by simultaneously recorded cortical ensembles. We predicted temporal intervals from the activity of hundreds of neurons recorded in motor and premotor cortex as rhesus monkeys performed self-timed hand movements. During the delay periods, when animals had to estimate temporal intervals and prepare hand movements, neuronal ensemble activity encoded both the time that elapsed from the previous hand movement and the time until the onset of the next. The neurons that were most informative of these temporal intervals increased or decreased their rates throughout the delay until reaching a threshold value, at which point a movement was initiated. Variability in the self-timed delays was explainable by the variability of neuronal rates, but not of the threshold. In addition to predicting temporal intervals, the same neuronal ensemble activity was informative for generating predictions that dissociated the delay periods of the task from the movement periods. Left hemispheric areas were the best source of predictions in one bilaterally implanted monkey overtrained to perform the task with the right hand. However, after that monkey learned to perform the task with the left hand, its left hemisphere continued and the right hemisphere started contributing to the prediction. We suggest that decoding of temporal intervals from bilaterally recorded cortical ensembles could improve the performance of neural prostheses for restoration of motor function.
Modulation of NMDA Receptor Properties and Synaptic Transmission by the NR3A Subunit in Mouse Hippocampal and Cerebrocortical Neurons
Authors: Tong Gary , Takahashi Hiroto , Tu Shichun , Shin Yeonsook , Talantova Maria , Zago Wagner , Xia Peng , Nie Zhiguo , Goetz Thomas , Zhang Dongxian , Lipton Stuart A. , Nakanishi Nobuki
Published: November 2007

Expression of the NR3A subunit with NR1/NR2 in Xenopus oocytes or mammalian cell lines leads to a reduction in N-methyl-d-aspartate (NMDA)-induced currents and decreased Mg2+sensitivity and Ca2+permeability compared with NR1/NR2 receptors. Consistent with these findings, neurons from NR3A knockout (KO) mice exhibit enhanced NMDA-induced currents. Recombinant NR3A can also form excitatory glycine receptors with NR1 in the absence of NR2. However, the effects of NR3A on channel properties in neurons and synaptic transmission have not been fully elucidated. To study physiological roles of NR3A subunits, we generated NR3A transgenic (Tg) mice. Cultured NR3A Tg neurons exhibited two populations of NMDA receptor (NMDAR) channels, reduced Mg2+sensitivity, and decreased Ca2+permeability in response to NMDA/glycine, but glycine alone did not elicit excitatory currents. In addition, NMDAR-mediated excitatory postsynaptic currents (EPSCs) in NR3A Tg hippocampal slices showed reduced Mg2+sensitivity, consistent with the notion that NR3A subunits incorporated into synaptic NMDARs. To study the function of endogenous NR3A subunits, we compared NMDAR-mediated EPSCs in NR3A KO and WT control mice. In NR3A KO mice, the ratio of the amplitudes of the NMDAR-mediated component to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated component of the EPSC was significantly larger than that seen in WT littermates. This result suggests that NR3A subunits contributed to the NMDAR-mediated component of the EPSC in WT mice. Taken together, these results show that NR3A subunits contribute to NMDAR responses from both synaptic and extrasynaptic receptors, likely composed of NR1, NR2, and NR3 subunits.
Coding of Auditory-Stimulus Identity in the Auditory Non-Spatial Processing Stream
Authors: Russ Brian E. , Ackelson Ashlee L. , Baker Allison E. , Cohen Yale E.
Published: November 2007

The neural computations that underlie the processing of auditory-stimulus identity are not well understood, especially how information is transformed across different cortical areas. Here, we compared the capacity of neurons in the superior temporal gyrus (STG) and the ventrolateral prefrontal cortex (vPFC) to code the identity of an auditory stimulus; these two areas are part of a ventral processing stream for auditory-stimulus identity. Whereas the responses of neurons in both areas are reliably modulated by different vocalizations, STG responses code significantly more vocalizations than those in the vPFC. Together, these data indicate that the STG and vPFC differentially code auditory identity, which suggests that substantial information processing takes place between these two areas. These findings are consistent with the hypothesis that the STG and the vPFC are part of a functional circuit for auditory-identity analysis.
Toy Models of a Nonassociative Quantum Mechanics
Authors: Dzhunushaliev Vladimir
Published: November 2007

Toy models of a nonassociative quantum mechanics are presented. The Heisenberg equation of motion is modified using a nonassociative commutator. Possible physical applications of a nonassociative quantum mechanics are considered. The idea is discussed that a nonassociative algebra could be the operator language for the nonperturbative quantum theory. In such approach the nonperturbative quantum theory has observables and unobservables quantities.
The Advantage of PET and CT Integration in Examination of Lung Tumors
Authors: Lu Guangming , Wang Zhongqiu , Zhu Hong , Chang Linfeng , Chen Yingxin , Wu Jiang , Zhao Yane
Published: November 2007

Purpose. To evaluate the diagnosis value of integrated positron emission tomography and computed tomography (PET/CT) with lung masses, this study emphasized the correlation between tumor size and maximum standardized uptake value (SUVmax) in selected regions of interest (ROI) of lung masses. Material and Methods. A retrospective analysis was performed on 85 patients with solid pulmonary lesions, all verified by pathology. The morphology, edge (speculated margins and lobule), size, density of pulmonary masses, and on‐chest CT images were reviewed. The SUVmax in ROI of pulmonary masses was calculated. Results. Among the 85 patients with lung masses, 59 patients presented with pulmonary malignant neoplasm and 26 patients with benign lesions. The sensitivity, specificity, and accuracy were 89.8%, 61.5%, 81.2%, respectively, for PET measurement only, 88.1%, 65.4%, 81.2% for CT only, and 96.6%, 80.8%, 91.8% for PET/CT. The size of pulmonary malignant neoplasm in the 59 patients was apparently correlated with the ROI′s SUVmax (r = 0.617, P < .001). However, the size of pulmonary benign mass in the 26 patients was not correlated with the SUVmax. Conclusion. PET/CT is of greater value in characterization of lung masses than PET and CT performed separately. The examination of lung tumor can be further specified by the correlation between the size of pulmonary malignant neoplasm and the ROI′s SUVmax.
Image Authentication Using Added Signal-Dependent Noise
Authors: Cindy Guo Xin , Hatzinakos Dimitrios
Published: November 2007

Image authentication has applications in security systems, photo forensics, and photo journalism. This paper presents an image authentication scheme using added signal-dependent noise. Imperceptible noise is embedded into the image at the time of acquisition according to the film grain noise model. During authentication, the image is divided into key-dependent overlapping blocks and the parameters of the embedded noise are extracted. The variance of the extracted parameters can be used to show the authenticity of an image. Test results indicate that the proposed algorithm is robust against content-preserving modifications such as JPEG compression and at the same time is capable of detecting malicious tampering.
Realization of IIR Decimation Filters Based on Merged Delay Transformation
Authors: Farooq Umar , Jamal Habibullah , Khan Shoab Ahmed
Published: November 2007

A novel realization of IIR decimation filters is proposed which is based on merged delay transformation. The transformation is derived analytically and can be applied directly to first- and second-order IIR filters. Computational efficiency is enhanced because the current output can be directly computed fromMth old output. The output data rate is decreased byMby mergingMnumber of delay elements in the recursive path. The proposed transformation is applied to higher-order IIR filter by decomposing it into parallel first-order and second-order sections. This transformation not only gives better stability for coefficient quantization but also reduces the requirement on processing clock, for sample, rate reduction. Filtering and down sampling are performed in the same stage. Number of multiplications is reduced by 45% as compared to the conventional IIR filters where all output samples are computed.
Characterization of Entire Sequences via Double Orlicz Space
Authors: Subramanian N. , Nallaswamy R. , Saivaraju N.
Published: November 2007

LetΓdenote the space of all entire sequences and∧the space of all analytic sequences. This paper is a study of the characterization and general properties of entire sequences via double Orlicz space ofΓM2ofΓ2establishing some inclusion relations.
A Subspace Method for Dynamical Estimation of Evoked Potentials
Authors: Georgiadis Stefanos D. , Ranta-aho Perttu O. , Tarvainen Mika P. , Karjalainen Pasi A.
Published: November 2007

It is a challenge in evoked potential (EP) analysis to incorporate prior physiological knowledge for estimation. In this paper, we address the problem of single-channel trial-to-trial EP characteristics estimation. Prior information about phase-locked properties of the EPs is assesed by means of estimated signal subspace and eigenvalue decomposition. Then for those situations that dynamic fluctuations from stimulus-to-stimulus could be expected, prior information can be exploited by means of state-space modeling and recursive Bayesian mean square estimation methods (Kalman filtering and smoothing). We demonstrate that a few dominant eigenvectors of the data correlation matrix are able to model trend-like changes of some component of the EPs, and that Kalman smoother algorithm is to be preferred in terms of better tracking capabilities and mean square error reduction. We also demonstrate the effect of strong artifacts, particularly eye blinks, on the quality of the signal subspace and EP estimates by means of independent component analysis applied as a prepossessing step on the multichannel measurements.
The Contribution of Endozoochory to the Colonization and Vegetation Composition of Recently Formed Sand Coastal Dunes
Authors: Dellafiore C. M. , Gallego-Fernández J. B. , Vallés S. Muñoz
Published: November 2007

The objective of this study was to determine whether endozoochory contributes to the dispersal and colonization of plant species in recently formed coastal dunes. At least 5.7% of species present in the study area are being dispersed by wild rabbits (Oryctolagus cuniculusL.). Most dispersed species are perennial herbs with small seeds size. The continuous input of seeds through rabbit feces into newly created areas would ensure the constant arrival of seeds and would facilitate colonization. Therefore, endozoochorous dispersal may play a relevant role for the structure and composition of dune plant communities.
Time-Resolved Analysis of a Highly Sensitive Förster Resonance Energy Transfer Immunoassay Using Terbium Complexes as Donors and Quantum Dots as Acceptors
Authors: Hildebrandt Niko , Charbonnière Loïc J. , Löhmannsröben Hans-Gerd
Published: November 2007

CdSe/ZnS core/shell quantum dots (QDs) are used as efficient Förster Resonance Energy Transfer (FRET) acceptors in a time-resolved immunoassays with Tb complexes as donors providing a long-lived luminescence decay. A detailed decay time analysis of the FRET process is presented. QD FRET sensitization is evidenced by a more than 1000-fold increase of the QD luminescence decay time reaching ca. 0.5 milliseconds, the same value to which the Tb donor decay time is quenched due to FRET to the QD acceptors. The FRET system has an extremely large Förster radius of approx. 100 Å and more than 70% FRET efficiency with a mean donor-acceptor distance of ca. 84 Å, confirming the applied biotin-streptavidin binding system. Time-resolved measurement allows for suppression of short-lived emission due to background fluorescence and directly excited QDs. By this means a detection limit of 18 attomol QDs within the immunoassay is accomplished, an improvement of more than two orders of magnitude compared to commercial systems.
Clustering Approach to Quantify Long-Term Spatio-Temporal Interactions in Epileptic Intracranial Electroencephalography
Authors: Hegde Anant , Erdogmus Deniz , Shiau Deng S. , Principe Jose C. , Sackellares Chris J.
Published: November 2007

Abnormal dynamical coupling between brain structures is believed to be primarily responsible for the generation of epileptic seizures and their propagation. In this study, we attempt to identify the spatio-temporal interactions of an epileptic brain using a previously proposed nonlinear dependency measure. Using a clustering model, we determine the average spatial mappings in an epileptic brain at different stages of a complex partial seizure. Results involving 8 seizures from 2 epileptic patients suggest that there may be a fixed pattern associated with regional spatio-temporal dynamics during the interictal to pre-post-ictal transition.
Acute Inflammatory Demyelinating Polyneuropathy and a Unilateral Babinski/Plantar Reflex
Authors: Cattano Davide , O'connor Brian , Shakir Ra'ad , Giunta Francesco , Palazzo Mark
Published: November 2007

Acquired acute demyelinating peripheral polyneuropathy (AADP) is a general classification of pathologies that could affect secondary the peripheral nervous system. They are characterized by an autoimmune process directed towards myelin. Clinically they are characterized by progressive weakness and mild sensory changes. Acute inflammatory demyelinating polyneuropathy often is referred to as Guillain-Barré syndrome (GBS). GBS is the major cause of acute nontraumatic paralysis in healthy people and it is caused by autoimmune response to viral agents (influenza, coxsackie, Epstein-Barr virus, or cytomegalovirus) or bacterial infective organisms (Campylobacter jejuni, Mycoplasma pneumoniae). A detailed history, with symptoms of progressive usually bilateral weakness, hyporeflexia, with a typical demyelinating EMG pattern supports the diagnosis. Progressive affection of respiratory muscles and autonomic instability coupled with a protracted and unpredictable recovery normally results in the need for ICU management. We present a case report of a patient with a typical GBS presentation but with a unilateral upgoing plantar reflex (Babinski sign). A unifying diagnosis was made and based on a literature search in Pubmed appears to be the first described case of its kind.