bluuebunny/crossref_metadata_2025 huggingface dataset:
Causality interfaces for actor networks
Authors: Zhou Ye , Lee Edward A.
Published: May 2008

We consider concurrent models of computation where “actors” (components that are in charge of their own actions) communicate by exchanging messages. The interfaces of actors principally consist of “ports,” which mediate the exchange of messages. Actor-oriented architectures contrast with and complement object-oriented models by emphasizing the exchange of data between concurrent components rather than transformation of state. Examples of such models of computation include the classical actor model, synchronous languages, data-flow models, process networks, and discrete-event models. Many experimental and production languages used to design embedded systems are actor oriented and based on one of these models of computation. Many of these models of computation benefit considerably from having access to causality information about the components. This paper augments the interfaces of such components to include such causality information. It shows how this causality information can be algebraically composed so that compositions of components acquire causality interfaces that are inferred from their components and the interconnections. We illustrate the use of these causality interfaces to statically analyze timed models and synchronous language compositions for causality loops and data-flow models for deadlock. We also show that that causality analysis for each communication cycle can be performed independently and in parallel, and it is only necessary to analyze one port for each cycle. Finally, we give a conservative approximation technique for handling dynamically changing causality properties.
Compositional real-time scheduling framework with periodic model
Authors: Shin Insik , Lee Insup
Published: May 2008

It is desirable to develop large complex systems using components based on systematic abstraction and composition. Our goal is to develop a compositional real-time scheduling framework to support abstraction and composition techniques for real-time aspects of components. In this paper, we present a formal description of compositional real-time scheduling problems, which are the
component abstraction
and
composition
problems. We identify issues that need be addressed by solutions and provide our framework for the solutions, which is based on the
periodic interface
. Specifically, we introduce the periodic resource model to characterize resource allocations provided to a single component. We present exact schedulability conditions for the standard Liu and Layland periodic task model and the proposed periodic resource model under EDF and RM scheduling, and we show that the component abstraction and composition problems can be addressed with periodic interfaces through the exact schedulability conditions. We also provide the utilization bounds of a periodic task set over the periodic resource model and the abstraction bounds of periodic interfaces for a periodic task set under EDF and RM scheduling. We finally present the analytical bounds of overheads that our solution incurs in terms of resource utilization increase and evaluate the overheads through simulations.
NWSLite
Authors: Gurun Selim , Krintz Chandra , Wolski Rich
Published: May 2008

Time series-based prediction methods have a wide range of uses in embedded systems. Many OS algorithms and applications require accurate prediction of demand and supply of resources. However, configuring prediction algorithms is not easy, since the dynamics of the underlying data requires continuous observation of the prediction error and dynamic adaptation of the parameters to achieve high accuracy. Current prediction methods are either too costly to implement on resource-constrained devices or their parameterization is static, making them inappropriate and inaccurate for a wide range of datasets. This paper presents NWSLite, a prediction utility that addresses these shortcomings on resource-restricted platforms.
Social television and user interaction
Authors: Cesar Pablo , Chorianopoulos Konstantinos , Jensen Jens F.
Published: May 2008

At first glance, the notion of social interactive television seems to be a tautology. Television watching has always been a social activity. People watch television together in their living rooms, and outside their homes they talk about last night's football match; and even call each other to recommend an interesting program. Unfortunately, until recently, research on social interactive television has been scarce. One limiting factor for the development of innovative services for the home is the interactive technology behind user interaction, which was limited to the remote control. Fortunately, a number of studies concentrate on extending interactive methods, for example by using contextual information. This article reviews the state of the art in these two directions: the social aspects of television and user interaction. We conclude with a research agenda for further research, which might transform current interactive television services into shared experiences.
Designing new interfaces for digital interactive television usable by older adults
Authors: Rice Mark , Alm Norman
Published: May 2008

The adoption of digital television (DTV), if appropriately designed, could be particularly attractive for older people, who tend to be overlooked when new services and applications are introduced, and remain a marginalized segment of the television broadcasting population. This article explores a range of methodologies and interactive approaches designed to support older people who have difficulties in using current interface models for DTV. Following an extensive requirements-gathering exercise, four different navigational layouts with a simplified remote control were tested and evaluated with older users to assess their ease of use. The results demonstrated the expected difficulties in understanding some of the terminology and interactive concepts utilized in "traditional" DTV design. Aspects of the experimental layouts suggest promising new directions in the development of visualization and navigation metaphors for user-led activities on DTV for older adults.
Awareness and conversational context-sharing to enrich TV-based communication
Authors: Hemmeryckx-Deleersnijder Bart , Thorne Jeremy M.
Published: May 2008

This article discusses domestic video-calling over the TV and how such an experience might be enhanced through awareness and context-sharing. Video-based awareness will provide a visual sense of togetherness, such that users feel more connected and the perceived barrier to entering the call will be lowered. Rich contextsharing within the call allows conversations to flow more freely as callers throw items (photos, for example) from each others' lives onto the virtual "table" for discussion. We also discuss some mechanisms to transition between awareness and a context- enriched call; we structure the article around a family scenario.
The uses of social television
Authors: Harboe Gunnar , Massey Noel , Metcalf Crysta , Wheatley David , Romano Guy
Published: May 2008

We present the results of two studies on social television concepts. In one study, a social TV prototype was tested in the field, allowing groups of users watching television at home to talk to each other over an audio link. Specific patterns of use are described, showing that users did perceive the system as valuable. In another study, focus groups were presented with several social TV concepts, and their responses were collected. These participants saw only moderate to marginal value in the concept. We discuss the discrepancy with reference to the limitations of each method. Based on our analysis, we conclude that our social television experience provides user value under certain favorable conditions. Participants deal with potential conflicts between conversation and television audio without the need for additional technical support, and there is no indication that a video link would improve the experience. However, designing for the social dynamics at the beginnings, ends, and outside of conversations remains an open challenge.
Achieving simultaneous distribution control and privacy protection for Internet media delivery
Authors: Chen Songqing , Chen Shiping , Guo Huiping , Shen Bo , Jajodia Sushil
Published: May 2008

Massive Internet media distribution demands prolonged continuous consumption of networking and disk bandwidths in large capacity. Many proxy-based Internet media distribution algorithms and systems have been proposed, implemented, and evaluated to address the scalability and performance issue. However, few of them have been used in practice, since two important issues are not satisfactorily addressed. First, existing proxy-based media distribution architectures lack an efficient media distribution control mechanism. Without copyright protection, content providers are hesitant to use proxy-based fast distribution techniques. Second, little has been done to protect client privacy during content accesses on the Internet. Straightforward solutions to address these two issues independently lead to conflicts. For example, to enforce distribution control, only legitimate users should be granted access rights. However, this normally discloses more information (such as which object the client is accessing) other than the client identity, which conflicts with the client's desire for privacy protection. In this article, we propose a unified proxy-based media distribution protocol to effectively address these two problems simultaneously. We further design a set of new algorithms in a cooperative proxy environment where our proposed scheme works efficiently and practically. Simulation-based experiments are conducted to extensively evaluate the proposed system. Preliminary results demonstrate the effectiveness of our proposed strategy.
Distributed musical performances
Authors: Zimmermann Roger , Chew Elaine , Ay Sakire Arslan , Pawar Moses
Published: May 2008

An increasing number of novel applications produce a rich set of different data types that need to be managed efficiently and coherently. In this article we present our experience with designing and implementing a data management infrastructure for a distributed immersive performance (DIP) application. The DIP project investigates a versatile framework for the capture, recording, and replay of video, audio, and MIDI (Musical Instrument Digital Interface) streams in an interactive environment for collaborative music performance. We are focusing on two classes of data streams that are generated within this environment. The first category consists of high-resolution isochronous media streams, namely audio and video. The second class comprises MIDI data produced by electronic instruments. MIDI event sequences are alphanumeric in nature and fall into the category of the data streams that have been of interest to data management researchers in recent years.

We present our data management architecture, which provides a repository for all DIP data. Streams of both categories need to be acquired, transmitted, stored, and replayed in real time. Data items are correlated across different streams with temporal indices. The audio and video streams are managed in our own High-performance Data Recording Architecture (HYDRA), which integrates multistream recording and retrieval in a consistent manner. This paper reports on the practical issues and challenges that we encountered during the design, implementation and experimental phases of our prototype. We also present some analysis results and discuss future extensions for the architecture.
On the accuracy and complexity of rate-distortion models for fine-grained scalable video sequences
Authors: Hsu Cheng-Hsin , Hefeeda Mohamed
Published: May 2008

Rate-distortion (R-D) models are functions that describe the relationship between the bitrate and expected level of distortion in the reconstructed video stream. R-D models enable optimization of the received video quality in different network conditions. Several R-D models have been proposed for the increasingly popular fine-grained scalable video sequences. However, the models' relative performance has not been thoroughly analyzed. Moreover, the time complexity of each model is not known, nor is the range of bitrates in which the model produces valid results. This lack of quantitative performance analysis makes it difficult to select the model that best suits a target streaming system. In this article, we classify, analyze, and rigorously evaluate all R-D models proposed for FGS coders in the literature. We classify R-D models into three categories: analytic, empirical, and semi-analytic. We describe the characteristics of each category. We analyze the R-D models by following their mathematical derivations, scrutinizing the assumptions made, and explaining when the assumptions fail and why. In addition, we implement all R-D models, a total of eight, and evaluate them using a diverse set of video sequences. In our evaluation, we consider various source characteristics, diverse channel conditions, different encoding/decoding parameters, different frame types, and several performance metrics including accuracy, range of applicability, and time complexity of each model. We also present clear systematic ways (pseudo codes) for constructing various R-D models from a given video sequence. Based on our experimental results, we present a justified list of recommendations on selecting the best R-D models for video-on-demand, video conferencing, real-time, and peer-to-peer streaming systems.
Algorithm 874
Authors: Wang R. , Keast P. , Muir P. H.
Published: May 2008

In this article we discuss a new software package, BACOLR, for the numerical solution of a general class of time-dependent 1-D PDEs. This package employs high-order adaptive methods in time and space within a method-of-lines approach and provides tolerance control of the spatial and temporal errors. The DAEs resulting from the spatial discretization (based on B-spline collocation) are handled by a substantially modified version of the Runge-Kutta solver, RADAU5. For each time step, the RADAU5 code computes an estimate of the temporal error and requires it to satisfy the user tolerance. After each time step BACOLR then computes a high-order estimate of the spatial error and requires this error estimate to satisfy the user tolerance. BACOLR was developed through a substantial modification of the adaptive method-of-lines package, BACOL. In this article we introduce the BACOLR package and present numerical results to show that the performance of BACOLR is comparable to and in some cases significantly superior to that of BACOL, which was shown in previous work to be more efficient, reliable and robust than other existing codes, especially for problems with solutions exhibiting narrow spikes or boundary layers.
A proposal for an integrated memory acquisition mechanism
Authors: Libster Eugene , Kornblum Jesse D.
Published: May 2008

Volatile memory forensics has become increasingly prominent in forensic analysis and incident response. Unfortunately there is currently no forensically sound method of acquiring an image of a system's memory without attaching specialized hardware. This paper proposes the addition of a memory acquisition mechanism to the operating system, thereby removing the need to load an external program. The method minimizes the acquisition's impact on the system's state, as well as making it more difficult for malicious programs to avoid detection or interfere with the memory dump. The risks of allowing a full memory capture and some considerations on how this method would interact with rootkits are also discussed.
Seeing the invisible
Authors: Maggi Federico , Zanero Stefano , Iozzo Vincenzo
Published: May 2008

Anti-forensics is the practice of circumventing classical forensics analysis procedures making them either unreliable or impossible. In this paper we propose the use of machine learning algorithms and anomaly detection to cope with a wide class of definitive anti-forensics techniques. We test the proposed system on a dataset we created through the implementation of an innovative technique of anti-forensics, and we show that our approach yields promising results in terms of detection.
Human gastrin-releasing peptide receptor gene regulation requires transcription factor binding at two distinct CRE sites
Authors: Chinnappan Dharmaraj , Qu Xiangping , Xiao Dongmei , Ratnasari Anita , Weber H. Christian
Published: May 2008

Ectopic expression of the gastrin-releasing peptide (GRP) receptor (GRP-R) occurs frequently in human malignancies of the gastrointestinal tract. Owing to paracrine and autocrine interaction with its specific high-affinity ligand GRP, tumor cell proliferation, migration, and invasion might ensue. Here we provide the first insights regarding molecular mechanisms of GRP-R regulation in gastrointestinal cancer cells. We identified by EMSA and chromatin immunoprecipitation assays two cAMP response element (CRE) binding sites that recruited transcription factor CRE binding protein (CREB) to the human GRP-R promoter. Transfection studies with a wild-type human GRP-R promoter reporter and corresponding CRE mutants showed that both CRE sites are critical for basal transcriptional activation in gastrointestinal cancer cells. Forced expression of cAMP-dependent effectors CREB and PKA resulted in robust upregulation of human GRP-R transcriptional activity, and this overexpression strictly required intact wild-type CRE sites. Direct cAMP stimulation with forskolin resulted in enhanced human GRP-R promoter activity only in HuTu-80 cells, but not in Caco-2 cells, coinciding with forskolin-induced CREB phosphorylation occurring only in HuTu-80 but not Caco-2 cells. In summary, CREB is a critical regulator of human GRP-R expression in gastrointestinal cancer and might be activated through different upstream intracellular pathways.
Cannabinoid CB2 receptors in the enteric nervous system modulate gastrointestinal contractility in lipopolysaccharide-treated rats
Authors: Duncan Marnie , Mouihate Abdeslam , Mackie Ken , Keenan Catherine M. , Buckley Nancy E. , Davison Joseph S. , Patel Kamala D. , Pittman Quentin J. , Sharkey Keith A.
Published: May 2008

Enhanced intestinal transit due to lipopolysaccharide (LPS) is reversed by cannabinoid (CB)2 receptor agonists in vivo, but the site and mechanism of action are unknown. We have tested the hypothesis that CB2 receptors are expressed in the enteric nervous system and are activated in pathophysiological conditions. Tissues from either saline- or LPS-treated (2 h; 65 μg/kg ip) rats were processed for RT-PCR, Western blotting, and immunohistochemistry or were mounted in organ baths where electrical field stimulation was applied in the presence or absence of CB receptor agonists. Whereas the CB2 receptor agonist JWH133 did not affect the electrically evoked twitch response of the ileum under basal conditions, in the LPS-treated tissues JWH133 was able to reduce the enhanced contractile response in a concentration-dependent manner. Rat ileum expressed CB2 receptor mRNA and protein under physiological conditions, and this expression was not affected by LPS treatment. In the myenteric plexus, CB2 receptors were expressed on the majority of neurons, although not on those expressing nitric oxide synthase. LPS did not alter the distribution of CB2 receptor expression in the myenteric plexus. In vivo LPS treatment significantly increased Fos expression in both enteric glia and neurons. This enhanced expression was significantly attenuated by JWH133, whose action was reversed by the CB2 receptor antagonist AM630. Taking these facts together, we conclude that activation of CB2 receptors in the enteric nervous system of the gastrointestinal tract dampens endotoxin-induced enhanced intestinal contractility.
Mast cell-dependent anorexia and hypothermia induced by mucosal activation of Toll-like receptor 7
Authors: Hayashi Tomoko , Cottam Howard B. , Chan Michael , Jin Guangyi , Tawatao Rommel I. , Crain Brian , Ronacher Lisa , Messer Karen , Carson Dennis A. , Corr Maripat
Published: May 2008

Systemic viral infections produce a highly regulated set of responses in sickness behavior, such as fever, anorexia, and adipsia. Toll-like receptor (TLR)7, activated by viral RNA during infection, potently stimulates the innate and adaptive immune responses that aid in viral clearance. However, the physiological consequences of TLR7 activation have not been thoroughly studied. In these experiments, we used a potent synthetic TLR7 ligand, 9-benzyl-8-hydroxy-2-(2-methoxyethoxy)adenine ( SM360320 ; 1V136), to investigate the consequences of TLR7 activation in genetically defined strains of mice. Administration of the drug by the nasal, intragastric, or intraperitoneal routes caused transient hypophagia, hypodypsia, and hypothermia. Analyses of mutant mouse strains indicated that these effects were dependent on the expression of TLR7, its adaptor protein MyD88, and TNF-α, and independent of IL-1β, IL-6 and cyclo-oxygenase-1 (COX1). Partial roles were also implied for mast cells and COX2. Although plasma TNF-α levels were significantly higher after systemic drug delivery, the behavioral effects were maximal when the agent was administered to the mucosa. Tissue and mucosal mast cells are known to express high levels of TLR7 and to rapidly release TNF-α upon TLR7 ligation. Mice deficient in tissue mast cells, W/W(v), had significantly less anorexia after TLR7 activation, and this response was restored with mast cell reconstitution. Our results thus suggest that tissue mast cells may play a role in the anorexia induced by mucosal activation of TLR7.
Chronically ischemic mouse skeletal muscle exhibits myopathy in association with mitochondrial dysfunction and oxidative damage
Authors: Pipinos Iraklis I. , Swanson Stanley A. , Zhu Zhen , Nella Aikaterini A. , Weiss Dustin J. , Gutti Tanuja L. , McComb Rodney D. , Baxter B. Timothy , Lynch Thomas G. , Casale George P.
Published: May 2008

A myopathy characterized by mitochondrial pathology and oxidative stress is present in patients with peripheral arterial disease (PAD). Patients with PAD differ in disease severity, mode of presentation, and presence of comorbid conditions. In this study, we used a mouse model of hindlimb ischemia to isolate and directly investigate the effects of chronic inflow arterial occlusion on skeletal muscle microanatomy, mitochondrial function and expression, and oxidative stress. Hindlimb ischemia was induced by staged ligation/division of the common femoral and iliac arteries in C57BL/6 mice, and muscles were harvested 12 wk later. Muscle microanatomy was examined by bright-field microscopy, and mitochondrial content was determined as citrate synthase activity in muscle homogenates and ATP synthase expression by fluorescence microscopy. Electron transport chain (ETC) complexes I through IV were analyzed individually by respirometry. Oxidative stress was assessed as total protein carbonyls and 4-hydroxy-2-nonenal (HNE) adducts and altered expression and activity of manganese superoxide dismutase (MnSOD). Ischemic muscle exhibited histological features of myopathy and increased mitochondrial content compared with control muscle. Complex-dependent respiration was significantly reduced for ETC complexes I, III, and IV in ischemic muscle. Protein carbonyls, HNE adducts, and MnSOD expression were significantly increased in ischemic muscle. MnSOD activity was not significantly changed, suggesting MnSOD inactivation. Using a mouse model, we have demonstrated for the first time that inflow arterial occlusion alone, i.e., in the absence of other comorbid conditions, causes myopathy with mitochondrial dysfunction and increased oxidative stress, recapitulating the muscle pathology of PAD patients.
Bioluminescence imaging to monitor the in vivo distribution of administered mesenchymal stem cells in acute kidney injury
Authors: Tögel Florian , Yang Ying , Zhang Ping , Hu Zhuma , Westenfelder Christof
Published: May 2008

Effective and targeted delivery of cells to injured organs is critical to the development of cell therapies. However, currently available in vivo cell tracking methods still lack sufficient sensitivity and specificity. We examined, therefore, whether a highly sensitive and specific bioluminescence method is suitable to noninvasively image the organ distribution of administered mesenchymal stem cells (MSCs) in vivo. MSCs were transfected with a luciferase/neomycin phosphotransferase construct (luc/neo-MSC). Bioluminescence of these cells was measured (charge-coupled device camera) after treatment with luciferin, showing a linear increase of photon emission with rising cell numbers. To track these cells in vivo, groups of mice were injected with 1 × 105 luc/neo-MSCs/animal and imaged with bioluminescence imaging at various time points. Injection of cells in the suprarenal aorta showed diffuse distribution of cells in normal animals, whereas distinct localization to the kidneys was observed in mice with ischemia- and reperfusion-induced acute kidney injury (AKI). Intrajugular infusion of MSCs demonstrated predominant accumulation of cells in both lungs. In animals with AKI, detectable cell numbers declined over time, as assessed by bioluminescence imaging and confirmed by PCR, a process that was associated with low apoptosis levels of intrarenally located MSCs. In conclusion, the described bioluminescence technology provides a sensitive and safe tool for the repeated in vivo tracking of infused luc/neo-MSCs in all major organs. This method will be of substantial utility in the preclinical testing and design of cell therapeutic strategies in kidney and other diseases.
Regulation of cell survival by Na+/H+exchanger-1
Authors: Schelling Jeffrey R. , Abu Jawdeh Bassam G.
Published: May 2008

Na+/H+exchanger-1 (NHE1) is a ubiquitous plasma membrane Na+/H+exchanger typically associated with maintenance of intracellular volume and pH. In addition to the NHE1 role in electroneutral Na+/H+transport, in renal tubular epithelial cells in vitro the polybasic, juxtamembrane NHE1 cytosolic tail domain acts as a scaffold, by binding with ezrin/radixin/moesin (ERM) proteins and phosphatidylinositol 4,5-bisphosphate, which initiates formation of a signaling complex that culminates in Akt activation and opposition to initial apoptotic stress. With robust apoptotic stimuli renal tubular epithelial cell NHE1 is a caspase substrate, and proteolytic cleavage may permit progression to apoptotic cell death. In vivo, genetic or pharmacological NHE1 loss of function causes renal tubule epithelial cell apoptosis and renal dysfunction following streptozotocin-induced diabetes, ureteral obstruction, and adriamycin-induced podocyte toxicity. Taken together, substantial in vivo and in vitro data demonstrate that NHE1 regulates tubular epithelial cell survival. In contrast to connotations of NHE1 as an unimportant “housekeeping” protein, this review highlights that NHE1 activity is critical for countering tubular atrophy and chronic renal disease progression.
Effect of duloxetine, a norepinephrine and serotonin reuptake inhibitor, on sneeze-induced urethral continence reflex in rats
Authors: Miyazato Minoru , Kaiho Yasuhiro , Kamo Izumi , Chancellor Michael B. , Sugaya Kimio , de Groat William C. , Yoshimura Naoki
Published: May 2008

We investigated the effect of duloxetine, a norepinephrine (NE) and serotonin (5-HT) reuptake inhibitor, on the neurally evoked urethral continence reflex induced by sneezing in rats. To clarify the role of noradrenergic and serotonergic mechanisms in preventing stress urinary incontinence (SUI) during sneezing, we examined the effect of duloxetine followed by intrathecal (it) methiothepin maleate (5-HT receptor and α1-adrenoceptor antagonist) or terazosin or idazoxan (selective α1- and α2-adrenoceptor antagonists, respectively). Amplitude of urethral pressure responses during sneezing (A-URS), urethral baseline pressure (UBP) at the midurethra, and sneeze-induced leak point pressure (S-LPP) were measured in normal adult female rats and rats with SUI induced by vaginal distension (VD). In normal and VD rats, intravenous application of duloxetine (1 mg/kg) increased A-URS by 35% and 34% and UBP by 21% and 34%, respectively. Sneezing-induced fluid leakage from the urethral orifice was observed in VD rats but not in normal rats. S-LPP was increased from 39.1 to 92.2 cmH2O by intravenous duloxetine in incontinent VD rats. Duloxetine-mediated enhancement of A-URS was inhibited by terazosin but not methiothepin maleate (it). In addition, simultaneous intrathecal application of methiothepin and terazosin induced a reduction in A-URS during sneezing, which was not increased by intravenous duloxetine. However, the reduced A-URS after intrathecal application of methiothepin and terazosin returned to the control level when duloxetine (iv) was applied after intrathecal idazoxan administration. These results indicate that duloxetine can prevent SUI by facilitating noradrenergic and serotonergic systems in the spinal cord to enhance the sneeze-induced active urethral closure mechanism.
Biology of claudins
Authors: Angelow Susanne , Ahlstrom Robert , Yu Alan S. L.
Published: May 2008

Claudins are a family of tight junction membrane proteins that regulate paracellular permeability of epithelia, likely by forming the lining of the paracellular pore. Claudins are expressed throughout the renal tubule, and mutations in two claudin genes are now known to cause familial hypercalciuric hypomagnesemia with nephrocalcinosis. In this review, we discuss recent advances in our understanding of the physiological role of various claudins in normal kidney function, and in understanding the fundamental biology of claudins, including the molecular basis for selectivity of permeation, claudin interactions in tight junction formation, and regulation of claudins by protein kinases and other intracellular signals.
Assessing recruitment of lung diffusing capacity in exercising guinea pigs with a rebreathing technique
Authors: Yilmaz Cuneyt , Dane D. Merrill , Hsia Connie C. W.
Published: May 2008

Noninvasive techniques for assessing cardiopulmonary function in small animals are limited. We previously developed a rebreathing technique for measuring lung volume, pulmonary blood flow, diffusing capacity for carbon monoxide (DlCO) and its components, membrane diffusing capacity (DmCO) and pulmonary capillary blood volume (Vc), and septal volume, in conscious nonsedated guinea pigs at rest. Now we have extended this technique to study guinea pigs during voluntary treadmill exercise with a sealed respiratory mask attached to a body vest and a test gas mixture containing 0.5% SF6 or Ne, 0.3% CO, and 0.8% C2H2 in 40% or 98% O2. From rest to exercise, O2 uptake increased from 12.7 to 25.5 ml·min−1·kg−1 while pulmonary blood flow increased from 123 to 239 ml/kg. The measured DlCO, DmCO, and Vc increased linearly with respect to pulmonary blood flow as expected from alveolar microvascular recruitment; body mass-specific relationships were consistent with those in healthy human subjects and dogs studied with a similar technique. The results show that 1) cardiopulmonary interactions from rest to exercise can be measured noninvasively in guinea pigs, 2) guinea pigs exhibit patterns of exercise response and alveolar microvascular recruitment similar to those of larger species, and 3) the rebreathing technique is widely applicable to human (∼70 kg), dog (20–30 kg), and guinea pig (1–1.5 kg). In theory, this technique can be extended to even smaller animals provided that species-specific technical hurdles can be overcome.
Motor Cortex Activation Induced by a Mirror: Evidence From Lateralized Readiness Potentials
Authors: Touzalin-Chretien Pascale , Dufour André
Published: May 2008

Similar motor regions are activated during voluntarily executed or observed movements. We investigated whether observing movements of one's own hand through a mirror will generate activations in the cortical motor regions of both the moving and nonmoving hands. Using the lateralized readiness potential (LRP), an electrophysiological correlate of premotor activation in the primary motor cortex, we recorded evoked responses to movements while subjects were viewing the performing (right) hand through a mirror placed sagittally, giving the impression that the left hand was performing the task. Reliable LRPs were recorded in relation to the seen hand, indicating motor cortex activity in the contralateral hemisphere of the inactive hand while the opposite hand was performing the movement.
Dynamics of Tuning in the Fourier Domain
Authors: Malone Brian J. , Ringach Dario L.
Published: May 2008

Neurons in primary visual cortex (area V1) are jointly tuned to the orientation and spatial frequency of sinusoidal stimuli (the Fourier domain). The role that suppressive mechanisms play in shaping the tuning and dynamics of cortical responses remains the subject of debate. Here we used subspace reverse correlation to study the relationship between suppression by nonoptimal stimuli, the spectral-temporal separability of the responses, and their persistence in time. Two clear relationships emerged from our data. First, cells with inseparable responses were often accompanied by suppression to nonpreferred stimuli, while separable responses showed mostly enhancement by their preferred stimuli. Second, inseparable responses were characterized by a longer persistence in time compared with those with separable dynamics. A parametric model that assumes the additive combination of separable enhancement and suppression signals, with suppression constrained to be low-pass in spatial frequency and untuned for orientation, explained the data well. These new findings, in addition to an established correlation between selectivity and suppression for nonoptimal stimuli, clarify how the dynamics and selectivity of cortical responses are shaped by suppressive signals and how their interplay generates the large diversity of responses observed in primary visual cortex.
q‐Genocchi Numbers and Polynomials Associated with Fermionic p‐Adic Invariant Integrals on ℤp
Authors: Jang Leechae , Kim Taekyun
Published: May 2008

The main purpose of this paper is to present a systemic study of some
families of multiple Genocchi numbers and polynomials. In particular, by using the
fermionic p‐adic invariant integral on ℤp, we construct p‐adic Genocchi numbers and
polynomials of higher order. Finally, we derive the following interesting formula: , where are the q‐Genocchi polynomials of order k.
Approximate Traveling Wave Solutions of Coupled Whitham‐Broer‐Kaup Shallow Water Equations by Homotopy Analysis Method
Authors: Rashidi M. M. , Ganji D. D. , Dinarvand S.
Published: May 2008

The homotopy analysis method (HAM) is applied to obtain the approximate traveling wave
solutions of the coupled Whitham‐Broer‐Kaup (WBK) equations in shallow water.
Comparisons are made between the results of the proposed method and exact solutions.
The results show that the homotopy analysis method is an attractive method in solving the systems
of nonlinear partial differential equations.
Prospects of 4H-SiC Double Drift Region IMPATT Device as a Photo-Sensitive High-Power Source at 0.7 Terahertz Frequency Regime
Authors: Mukherjee Moumita , Mazumder Nilratan , Roy Sitesh Kumar
Published: May 2008

The dynamic performance of wide-bandgap 4H-SiC based double drift region (p++ p n n++) IMPATT diode is simulated for the first time at terahertz frequency (0.7 Terahertz) region. The simulation experiment establishes the potential of SiC based IMPATT diode as a high power (2.5×1011 Wm−2) terahertz source. The parasitic series resistance in the device is found to reduce the RF power output by 10.7%. The effects of external radiation on the simulated diode are also studied. It is found that (i) the negative conductance and (ii) the negative resistance of the diode decrease, while, the frequency of operation and the quality factor shift upward under photoillumination. Holes in 4H-SiC based IMPATT are found to dominate the modulation activities. The inequality in the magnitude of electron and hole ionization rates in the semiconductors may be correlated with these findings.
Light Emission from Rare‐Earth Doped Silicon Nanostructures
Authors: Li J. , Zalloum O. H. Y. , Roschuk T. , Heng C. L. , Wojcik J. , Mascher P.
Published: May 2008

Rare earth (Tb or Ce)‐doped silicon oxides were deposited by electron cyclotron resonance plasma‐enhanced chemical vapour deposition (ECR‐PECVD). Silicon nanocrystals (Si‐ncs) were formed in the silicon‐rich films during certain annealing processes. Photoluminescence (PL) properties of the films were found to be highly dependent on the deposition parameters and annealing conditions. We propose that the presence of a novel sensitizer in the Tb‐doped oxygen‐rich films is responsible for the indirect excitation of the Tb emission, while in the Tb‐doped silicon‐rich films the Tb emission is excited by the Si‐ncs through an exciton‐mediated energy transfer. In the Ce‐doped oxygen‐rich films, an abrupt increase of the Ce emission intensity was observed after annealing at
1200∘C. This effect is tentatively attributed to the formation of Ce silicate. In the Ce‐doped silicon‐rich films, the Ce emission was absent at annealing temperatures lower than 1100∘C due to the strong absorption of Si‐ncs. Optimal film compositions and annealing conditions for maximizing the PL intensities of the rare earths in the films have been determined. The light emissions from these films were very bright and can be easily observed even under room lighting conditions.
In Vitro Evaluation of a Stable Monomeric Gold(II) Complex with Hematoporphyrin IX: Cytotoxicity against Tumor and Kidney Cells, Cellular Accumulation, and Induction of Apoptosis
Authors: Momekov Georgi , Ferdinandov Dilyan , Konstantinov Spiro , Arpadjan Sonja , Tsekova Daniela , Gencheva Galina , Bontchev Panayot R. , Karaivanova Margarita
Published: May 2008

The antineoplastic potential of a stable monomeric Au(II) complex with hematoporphyrin IX (Hp), namely [Au(II)Hp-2H.], was investigated in a panel of tumor cell lines. The complex exhibits strong cytotoxicity, whereby the leukaemia‐ and lymphoma‐derived cell lines are more sensitive, with IC50 values comparable to those of the reference anticancer drug cisplatin. In contrast, the solid tumor models are more sensitive to the platinum drug. A comparative assessment of both agents against the human kidney cell line 293T has shown that [Au(II)Hp-2H.] is less cytotoxic. The gold complex induces oligonucleosomal DNA fragmentation in tumour cells following 24‐hour treatment and hence its cytotoxic effect is at least partly mediated by induction of apoptotic cell death. A prominent intracellular gold accumulation was detected after treating tumor cells with [Au(II)Hp-2H.] which shows that its putative pharmacological targets are readily accessible after a short incubation period.
Characterization and Evaluation of the Efficiency of TiO2/Zinc Phthalocyanine Nanocomposites as Photocatalysts for Wastewater Treatment Using Solar Irradiation
Authors: Machado Antonio E. H. , França Marcela D. , Velani Valdemir , Magnino Gabriel A. , Velani Hosana M. M. , Freitas Flávio S. , Müller Paulo S. , Sattler Christian , Schmücker Martin
Published: May 2008

This work reports the characterization of composites prepared by the association between zinc phthalocyanine (ZnPc) and titanium dioxide. These composites are better photocatalysts for wastewater decontamination mediated by solar radiation than pure TiO2, performance that remains even when reused. The UV‐Vis diffuse reflectance absorption spectra show for these composites two intense absorption bands. The first covers the ultraviolet and part of the visible spectrum region until 460 nm (2.7 eV), whereas the second, nonstructured, goes from 475 nm until the near infrared with an absorption peak at 683 nm attributed to the Q band of ZnPc. The production of additional e−/h+ pairs by these aggregates when photoexcited, their capability to act as charge carrier, the thickness and regularity of their distribution on the TiO2 surface seem to be important parameters for the performance observed for these composites.
The Critical Role of PPARγ in Human Malignant Melanoma
Authors: Freudlsperger Christian , Schumacher Udo , Reinert Siegmar , Hoffmann Jürgen
Published: May 2008

The past 30 years have only seen slight improvement in melanoma therapy. Despite a wide variety of therapeutic options, current survival for patients with metastatic disease is only 6–8 months. Part of the reason for this treatment failure is the broad chemoresistance of melanoma, which is due to an altered survival capacity and an inactivation of apoptotic pathways. Several targetable pathways, responsible for this survival/apoptosis resistance in melanoma, have been described and current research has focused on mechanism inactivating these pathways. As PPARγ was shown to be constitutively active in several tumour entities and PPARγ agonists extent strong anticancer effects, the role of PPARγ as a possible target for specific anticancer strategy was investigated in numerous studies. However, only a few studies have focused on the effects of PPARγ agonists in melanoma, showing conflicting results. The use of PPARγ agonists in melanoma therapy has to be
carefully weighted against considerable,
undesirable side effects, as their mode of action is not fully
understood and even pro‐proliferative effects have
been described. In the current review, we discuss the role of
PPARs, in particular PPARγ in melanoma and their potential role as a molecular target for melanoma therapy.
Methylated Trivalent Arsenic‐Glutathione Complexes are More Stable than their Arsenite Analog
Authors: Percy Andrew J. , Gailer Jürgen
Published: May 2008

The trivalent arsenic glutathione complexes arsenic triglutathione,
methylarsonous diglutathione, and dimethylarsinous glutathione are key intermediates
in the mammalian metabolism of arsenite and possibly represent the arsenic species
that are transported from the liver to the kidney for urinary excretion. Despite this, the
comparative stability of the arsenic‐sulfur bonds in these complexes has not been
investigated under physiological conditions resembling hepatocyte cytosol. Using
size‐exclusion chromatography and a glutathione‐containing phosphate buffered saline
mobile phase (5 or 10 mM glutathione, pH 7.4) in conjunction with an
arsenic‐specific detector, we chromatographed arsenite, monomethylarsonous acid, and
dimethylarsinous acid. The on‐column formation of the corresponding arsenic‐glutathione
complexes between 4 and 37∘C revealed that methylated arsenic‐glutathione complexes are more
stable than arsenic triglutathione. The relevance of these results with regard to the metabolic
fate of arsenite in mammals is discussed.
UV‐Activated Luminescence/Colourimetric O2 Indicator
Authors: Mills Andrew , Tommons Cheryl , Bailey Raymond T. , Tedford M. Catriona , Crilly Peter J.
Published: May 2008

An oxygen indicator is described, comprising nanoparticles of titania dispersed in hydroxyethyl cellulose (HEC) polymer film containing a sacrificial electron donor, glycerol, and the redox indicator, indigo‐tetrasulfonate (ITS). The indicator is blue‐ coloured in the absence of UV light, however upon exposure to UV light it not only loses its colour but also luminesces, unless and until it is exposed to oxygen, whereupon its original colour is restored. The initial photobleaching spectral (absorbance and luminescence) response characteristics in air and in vacuum are described and discussed in terms of a simple reaction scheme involving UV activation of the titania photocatalyst particles, which are used to reduce the redox dye, ITS, to its leuco form, whilst simultaneously oxidising the glycerol to glyceraldehye. The response characteristics of the activated, that is, UV photobleached, form of the indicator to oxygen are also reported and the possible uses of such an indicator to measure ambient O2 levels are discussed.
Forma Analysis of Particle Swarm Optimisation for Permutation Problems
Authors: Gong Tao , Tuson Andrew L.
Published: May 2008

Particle swarm optimisation (PSO) is an innovative and competitive optimisation
technique for numerical optimisation with real‐parameter representation. In this paper, we examine the working mechanism of PSO in a principled manner with forma analysis and investigate the applicability of PSO
on the permutation problem domain. Particularly, our derived PSO schemes are empirically studied based on the quadratic assignment problem (QAP) benchmarks to justify its comparable performance, which in turn implies the benefits of our approach in applying PSO to the discrete problem domain.
Molecular Processes in Biological Thermosensation
Authors: Digel I. , Kayser P. , Artmann G. M.
Published: May 2008

Since thermal gradients are almost everywhere, thermosensation could represent one of the oldest sensory transduction processes that evolved in organisms. There are many examples of temperature changes affecting the physiology of living cells. Almost all classes of biological macromolecules in a cell (nucleic acids, lipids, proteins) can present a target of the temperature-related stimuli. This review discusses some features of different classes of temperature-sensing molecules as well as molecular and biological processes that involve thermosensation. Biochemical, structural, and thermodynamic approaches are applied in the paper to organize the existing knowledge on molecular mechanisms of thermosensation. Special attention is paid to the fact that thermosensitive function cannot be assigned to any particular functional group or spatial structure but is rather of universal nature. For instance, the complex of thermodynamic, structural, and functional features of hemoglobin family proteins suggests their possible accessory role as “molecular thermometers”.
Membranes of Polyvinylidene Fluoride and PVDF Nanocomposites with Carbon Nanotubes via Immersion Precipitation
Authors: Mago Gaurav , Kalyon Dilhan M. , Fisher Frank T.
Published: May 2008

Microporous polyvinylidene fluoride (PVDF) and PVDF nanocomposite membranes were prepared via an isothermal immersion precipitation method using two different antisolvents (ethanol and water). The structure and morphology of the resulting membranes were investigated by wide angle X‐ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The effects of the type of the antisolvent and the presence of multiwalled carbon nanotubes (MWNTs) on membrane morphology and the crystal structure developed within the membranes were studied. The crystallization of the PVDF upon immersion precipitation occurred predominantly in the α‐phase when water is used as the antisolvent or in the absence of the carbon nanotubes. On the other hand, β‐phase crystallization of the PVDF was promoted upon the use of ethanol as the antisolvent in conjunction with the incorporation of the MWNTs. The morphology and the total crystallinity of the PVDF membranes were also affected by the incorporation of the MWNTs and the antisolvent used, suggesting that the microstructure and the ultimate properties of the PVDF membranes can be engineered upon the judicious selection of crystallization conditions and the use of carbon nanotubes.
Existence and Global Exponential Stability of Periodic Solutions for General Neural Networks with Time‐Varying Delays
Authors: Yang Xinsong
Published: May 2008

By using the coincidence degree theorem and differential inequality
techniques, sufficient conditions are obtained for the existence and global exponential
stability of periodic solutions for general neural networks with time‐varying (including
bounded and unbounded) delays. Some known results are improved and some new
results are obtained. An example is employed to illustrate our feasible results.