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Microglia are major immunocompetent cells in the central nervous system and retain highly dynamic motility. The processes which allow these cells to move, such as chemotaxis and phagocytosis, are considered part of their functions and are closely related to purinergic signaling. Previously, we reported that the activation of the P2Y receptor by UDP stimulation in microglia evoked dynamic cell motility which enhanced their phagocytic capacity, as reported by Koizumi et al. (Nature 446(7139):1091-1095, ). These responses require actin cytoskeletal rearrangement, which is seen after UDP stimulation. However, the intracellular signaling pathway has not been defined. In this study, we found that UDP in rat primary microglia rapidly induced the transient phosphorylation at Ser157 of vasodilator-stimulated phosphoprotein (VASP). VASP, one of actin binding protein, accumulated at the plasma membrane where filamentous (F)-actin aggregated in a time-dependent manner. The phosphorylation of VASP was suppressed by inhibition of PKC. UDP-induced local actin aggregations were also abrogated by PKC inhibitors. The Rho inhibitor CT04 and the expression of p115-RGS, which suppresses G signaling, attenuated UDP-induced phosphorylation of VASP and actin aggregation. These results indicate that PKC- and Rho-dependent phosphorylation of VASP is involved in UDP-induced actin aggregation of microglia. [ABSTRACT FROM AUTHOR]

Scanning of ports on a computer occurs frequently on the Internet. An attacker performs port scans of Internet protocol addresses to find vulnerable hosts to compromise. However, it is also useful for system administrators and other network defenders to detect port scans as possible preliminaries to more serious attacks. It is a very difficult task to recognize instances of malicious port scanning. In general, a port scan may be an instance of a scan by attackers or an instance of a scan by network defenders. In this survey, we present research and development trends in this area. Our presentation includes a discussion of common port scan attacks. We provide a comparison of port scan methods based on type, mode of detection, mechanism used for detection and other characteristics. This survey also reports on the available data sets and evaluation criteria for port scan detection approaches. [ABSTRACT FROM AUTHOR]

UDP has been successfully applied in many fields, finding a subspace that maximizes the ratio of the nonlocal scatter to the local scatter. But UDP can not represent the nonlinear space well because it is a linear method in nature. Kernel methods can otherwise discover the nonlinear structure of the images. To improve the performance of UDP, kernel UDP (a nonlinear vision of UDP) is proposed for face feature extraction and face recognition via kernel tricks in this paper. We formulate the kernel UDP theory and develop a two-stage method to extract kernel UDP features: namely weighted Kernel PCA plus UDP. The experimental results on the FERET and ORL databases show that the proposed kernel UDP is effective. [ABSTRACT FROM AUTHOR]

Abstract: A new, homogeneous, high-throughput-compatible assay method is described for the fluorescence-based quantitation of nanomolar concentrations of ribonucleoside diphosphates (rNDPs). The principle of the method is the conversion of the rNDPs to RNA by the enzyme polynucleotide phosphorylase (EC 2.7.7.8) and detection of the RNA by the increased fluorescence of a commercial nucleic acid detection dye. A commercial RNA homopolymer complementary to the RNA product is included to increase the sensitivity for ADP and UDP. Standard curves for nanomolar concentrations of ADP, UDP, GDP, and CDP are shown. The assay detected 75nM ADP produced by the pyruvate kinase-catalyzed phosphorylation of pyruvate with a signal-to-baseline ratio of 2.8. The assay may be used in either a continuous or a discontinuous mode. [Copyright &y& Elsevier]

The IEEE 802.11 standard is a successful wireless local area networks (WLAN) technology, because of its easy deployment. With deployment of WLAN, the ability of the IEEE802.11 standard to support multimedia applications with high quality of service (QoS) requirements has increased. This paper evaluates the capacity of QoS support in Enhanced Distributed Channel Access (EDCA) mechanism of the IEEE 802.11e standard. The EDCA is an enhancement for QoS support in 802.11. EDCA mechanisms allow prioritized medium access for applications with high QoS requirements by assigning different priorities to the access categories. This study discusses the performance evaluation of 802.11 and 802.11e by simulations using the network simulator OmNET++. The parameters jitter, delay and throughput are calculated. A comparative Discussion between DCF und EDCA is constituted for different services, such as voice, video, best-effort and background traffic. The scenarios results show the QoS support of EDCA for different types of data traffic due to its service differentiation technique and its four access categories. With EDCA mechanism, network capacity is effectively increased and the support for multimedia applications transmissions is improved. [ABSTRACT FROM AUTHOR]

The article discusses a research study on optimizing roasting temperature for soybean cake evaluated by nitrogen (N)-factionation and in-situ protein degradability. Conducted by researchers was the in situ nylon bag technique and protein partitioning by subjecting feedstuffs to different solvents for digestion. Results showed that acid detergent insoluble N (ADIN) content increased with increasing temperature for roasting and no increase in user datagram protocol (UDP) content after the temperature of 160 degrees Celsius.

Abstract: The ASDEX Upgrade tokamak experiment is equipped with a versatile discharge monitoring and control system. It allows to develop and use advanced control algorithms to investigate plasma physics under well-defined conditions with the objective of optimising plasma performance. The achievable quality depends on the accuracy with which the plasma state can be reconstructed from measurements under real-time conditions. Today''s advanced algorithms need physics quantities – scalar entities as well as profiles. These are obtained processing huge numbers of raw measurements with complex diagnostic algorithms. Adequate network communication for the resulting signals is crucial to satisfy real-time requirements, especially when several diagnostic systems cooperate in a feedback control loop. Support for the technology of choice, however, is not easily available for all of the diverse, highly specialised diagnostic systems. We give an overview about the methods that have been explored at ASDEX Upgrade for real-time signal transfer. In particular, we investigated reflective shared memory and Ethernet technologies. Our solution strives to combine their strengths. For fast communication on dedicated computing nodes, reflective shared memory is used. For the majority of diagnostic systems producing large data blocks at moderate rates, Ethernet connections with UDP protocol are employed. Following ASDEX Upgrade''s framework concept, a software layer hides the networks used from both diagnostic and control applications. [Copyright &y& Elsevier]

The P2Y14 receptor is a relatively broadly expressed G protein-coupled receptor that is prominently associated with immune and inflammatory cells as well as with many epithelia. This receptor historically was thought to be activated selectively by UDP-glucose and other UDP-sugars. However, UDP is also a very potent agonist of this receptor, and may prove to be one of its most important cognate activators. [ABSTRACT FROM AUTHOR]

The IEEE 802.21 Media Independent Handover (MIH) working group is developing a set of mechanisms to facilitate migration of mobile users between access networks that use different link-layer technologies. Among these are mobility managers that create and process signaling messages to facilitate handovers. The MIH signaling architecture being developed in the Internet Engineering Task Force (IETF) allows any transport layer protocol to carry MIH messages. The IETF has considered using the unreliable but lightweight transport available with the User Datagram Protocol (UDP) as well as the reliable stream-oriented transport with congestion control offered by the Transmission Control Protocol (TCP). In this paper we develop mathematical models that result in expressions for the characteristic function of the time required to complete exchanges of an arbitrary number of MIH signaling messages between a mobile node (MN) and a remote mobility manager (MM). Our models also provide expressions for the average amount of overhead associated with MIH message exchanges due to retransmissions either by the MIH signaling entities or by the transport-layer protocol. In addition, we provide simulation results that confirm the results from the mathematical model and illustrate the effect of varying transport parameters such as the TCP maximum retransmission timeout. [ABSTRACT FROM AUTHOR]

Aims: Extracellular nucleotides are vasoactive molecules. The concentrations of these molecules are regulated by ectonucleotidases. In this study, we investigated the role of the blood vessel ectonucleotidase NTPDase1, in the vasoconstrictor effect of nucleotides using Entpd1−/− mice. [ABSTRACT FROM PUBLISHER]

In this paper we present our solution for improving the quality of communication in our particular desktop grid system, QADPZ, which consists of a dual communication mechanism. Thus, in order to improve the efficiency of communication, QADPZ support two different protocols (UDP and TCP/IP). To deal with the unreliability of UDP, an additional, more reliable level of communication has been added to the system, which works similarly with the real life postal service, delivering and receiving high-level message and implements a reliable, confirmation-based message exchange protocol. We point out that an unreliable transport mechanism that deals with packet loss gracefully and does not exhibit extreme losses can compete well with other more reliable transport protocols. [ABSTRACT FROM AUTHOR]

Abstract: Buffers in emerging optical packet routers are expensive resources, and it is expected that they would be able to store at most a few tens of KiloBytes of data in the optical domain. When TCP and real-time (UDP) traffic multiplex at an optical router with such small buffers (less than 50 KB), we recently showed that UDP packet loss can increase with increasing buffer size. This anomalous loss behaviour can negatively impact the investment made in larger buffers and degrade quality of service. In this paper we explore if this anomalous behaviour can be alleviated by dedicating (i.e., pre-allocating) buffers to UDP traffic. Our contributions within this context are two fold. First, we show using extensive simulations that there would seem to be a critical buffer size above which UDP benefits with dedicated buffers that protect it from the aggressive nature of TCP. However, for smaller buffers that are below this critical value, UDP can benefit by time-sharing the buffers with TCP. Second, we develop a simple linear model that quantitatively captures the combined utility of TCP and real-time traffic for shared and dedicated buffers, and propose a method to optimise the buffer split ratio with the objective of maximising the overall network utility. Our study equips designers of optical packet switched networks with quantitative tools to tune their buffer allocation strategies subject to various system parameters such as the ratio of traffic mix and relative weights associated with TCP and UDP traffic. [Copyright &y& Elsevier]

• GPCR receptor-P2Y6 was involved in mediating innate immune response in ALI process. • P2Y6 on neutrophil contributed to the of neutrophil infiltrating into lung tissues in ALI. • P2Y6 mediated neutrophil migration through cytoskeleton F-actin remodeling via ERK signaling pathway. • Deficiency of P2Y6 alleviated the development of ALI in mice. • Bone marrow and neutrophilic chimeras were taken in our P2Y6 deficienct ALI mouse model. Neutrophils play a prominent role in the inflammatory response and are a critical factor in the pathogenesis of acute lung injury (ALI). Despite a deep understanding of neutrophil accumulation in the pulmonary microvasculature during the process of this disease, the regulatory mechanism of neutrophil recruitment remains unclear. This study aimed to explore the functions and signaling pathways of the purinergic receptor P2Y 6 in mediating the innate immune response in ALI. P2Y 6 -deficient mice, bone marrow chimeras, and neutrophilic chimeras were created in this work to explore the function of P2Y 6 in ALI. The results indicated that the extracellular nucleotide UDP was released as a dangerous signal and activated P2Y 6 to promote the inflammatory response and pulmonary damage during the process of ALI. P2Y 6 deficiency may mitigate deterioration of this disease, including reduced ALI-related inflammatory factor release and immune cell invasion. Bone marrow and neutrophil chimeras and adoptive transfer in mice showed that P2Y 6 expression on neutrophils contributed to neutrophil infiltration into lung tissues induced by UDP. Further work indicated that P2Y 6 was involved in the neutrophil migration capability through the ErK signaling pathway by mediating the deformation of F-actin filaments and pseudopodia formation during cell recruitment to pulmonary tissue. Here, we provide evidence for the mechanism by which the purinergic receptor P2Y 6 contributes to ALI development by regulating neutrophil infiltration into lung tissues. These data indicated that P2Y 6 might be a potential therapeutic target for the treatment of this acute severe disease. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, an efficient feature extraction method named as constrained maximum variance mapping (CMVM) is developed. The proposed algorithm can be viewed as a linear approximation of multi-manifolds learning based approach, which takes the local geometry and manifold labels into account. The CMVM and the original manifold learning based approaches have a point in common that the locality is preserved. Moreover, the CMVM is globally maximizing the distances between different manifolds. After the local scatters have been characterized, the proposed method focuses on developing a linear transformation that can maximize the dissimilarities between all the manifolds under the constraint of locality preserving. Compared to most of the up-to-date manifold learning based methods, this trick makes contribution to pattern classification from two aspects. On the one hand, the local structure in each manifold is still kept; on the other hand, the discriminant information between manifolds can be explored. Finally, FERET face database, CMU PIE face database and USPS handwriting data are all taken to examine the effectiveness and efficiency of the proposed method. Experimental results validate that the proposed approach is superior to other feature extraction methods, such as linear discriminant analysis (LDA), locality preserving projection (LPP), unsupervised discriminant projection (UDP) and maximum variance projection (MVP). [Copyright &y& Elsevier]

Abstract: Activation of the Gq-coupled P2Y6 receptor heterologously expressed in astrocytes significantly attenuates apoptosis induced by tumor necrosis factor α (TNFα). We have extended the analysis of P2Y6 receptor-induced cytoprotection to mouse skeletal muscle cells endogenously expressing this receptor. The endogenous P2Y6 receptor agonist UDP and synthetic agonist MRS2693 protected C2C12 skeletal muscle cells against apoptosis in a concentration-dependent manner (0.1–10nM) as determined by propidium iodide staining, histochemical analysis using hematoxylin and Hoechst 33258, and DNA fragmentation. The insurmountable P2Y6 receptor antagonist MRS2578 blocked the protection. TNFα-induced apoptosis in C2C12 cells correlated with activation of the transcription factor NF-κB. The NF-κB activation was attenuated by 10nM MRS2693, which activated the antiapoptic ERK1/2 pathway. In an in vivo mouse hindlimb model, MRS2693 protected against skeletal muscle ischemia/reperfusion injury. The P2Y6 receptor is a novel cytoprotective receptor that deserves further exploration in ameliorating skeletal muscle injury. [Copyright &y& Elsevier]

Abstract: The phosphate, uracil, and ribose moieties of uracil nucleotides were varied structurally for evaluation of agonist activity at the human P2Y2, P2Y4, and P2Y6 receptors. The 2-thio modification, found previously to enhance P2Y2 receptor potency, could be combined with other favorable modifications to produce novel molecules that exhibit high potencies and receptor selectivities. Phosphonomethylene bridges introduced for stability in analogues of UDP, UTP, and uracil dinucleotides markedly reduced potency. Truncation of dinucleotide agonists of the P2Y2 receptor, in the form of Up4-sugars, indicated that a terminal uracil ring is not essential for moderate potency at this receptor and that specific SAR patterns are observed at this distal end of the molecule. Key compounds reported in this study include 9, α,β-methylene-UDP, a P2Y6 receptor agonist; 30, Up4-phenyl ester and 34, Up4-[1]glucose, selective P2Y2 receptor agonists; dihalomethylene phosphonate analogues 16 and 41, selective P2Y2 receptor agonists; 43, the 2-thio analogue of INS37217 (P1-(uridine-5′)-P4-(2′-deoxycytidine-5′)tetraphosphate), a potent and selective P2Y2 receptor agonist. [Copyright &y& Elsevier]

Embedded Ethernet technology has been utilized increasingly widely as the communication mode in the substation automation system (SAS). This paper introduces the current applying situation about embedded Ethernet in SAS First. After analyzing the protocol levels used in SAS based on embedded Ethernet and the differences between the TCP and UDP, UDP/IP is selected as the communication protocol between the station-level and bay-level devices for its real-time characteristic. Then a new kind of implementation of the embedded Ethernet is presented based on hardware protocol stack. The designed scheme can be implemented easily, reduce cost significantly and shorten developing cycle. [ABSTRACT FROM AUTHOR]

There is a vast literature on the throughput analysis of the IEEE 802.11 media access control (MAC) protocol. However, very little has been done on investigating the interplay between the cotlisioc avoidance mechanisms of the 802.11 MAC protocol and the dynamics of upper layer transpod protocols. In this paper, we tackle this issue from an analytical, simulative, and experimental perspective. Specifically, we develop Markov chain models to compute the distribution of the number of active stations in an 802.11 wireless local area network (WLAN) when long-lived Transmission Control Protocol (TCP) connections compete with finite-loed User Datagram Protocol (UDP) flows. By embedding these distributions in the MAC protocol modeling, we derive approximate but accurate expressions of the TCP and UDP throughput. We validate the model accuracy through performance tests carried out in a real WLAN for a wide range of configurations. Our analytical model and the supporting experimental outcomes show that 1) the total TCP throughput is basically independent of the number of open TCP connections and the aggregate TCP traffic can be equivalently modeled as two saturated flows and 2) in the saturated regime, n UDP flows obtain about n times the aggregate throughput achieved by the TCP flows, which is independent of the overall number of persistent TCP connections. [ABSTRACT FROM AUTHOR]

Abstract: Nucleotides can modify intraocular pressure (IOP). We have tested the ability of uridine-5′-diphosphate, UDP, for modulating IOP in New Zealand white rabbits. Uridine 5′ diphosphate, UDP, reduced IOP by 82.9±2.6% compared to control. Dose-response analysis demonstrated a concentration dependent pattern which presented a pD2 value of 7.57±1.45, equivalent to an EC50 of 26.91 nM. Of all the tested P2 receptor antagonists, suramin, pyridoxalphosphate-6-azophenyl-2, 4-disulfonic acid (PPADS) and Reactive Blue 2 (RB-2), only the last two were able to reverse the action triggered by UDP. Altogether, UDP acting probably on P2Y6 receptors present on the ciliary processes, can reduce intraocular pressure, indicating that this substance may be used for the treatment of ocular hypertension and glaucoma. [Copyright &y& Elsevier]

Malonic aciduria is a rare autosomal recessive disorder caused by deficiency of malonyl-CoA decarboxylase, encoded by the MLYCD gene. We report on a patient with clinical presentation in the neonatal period. Metabolic investigations led to a diagnosis of malonyl-CoA decarboxylase deficiency, confirmed by decreased activity in cultured fibroblasts. High doses of carnitine and a diet low in lipids led to a reduction in malonic acid excretion, and to an improvement in his clinical conditions, but at the age of 4 months he died suddenly and unexpectedly. No autopsy was performed. Molecular analysis of the MLYCD gene performed on the proband's RNA and genomic DNA identified a previously undescribed mutation (c.772–775delACTG) which was homozygous. This mutation was present in his mother but not in his father; paternity was confirmed by microsatellite analysis. A hypothesis of maternal uniparental disomy (UPD) was investigated using fourteen microsatellite markers on chromosome 16, and the results confirmed maternal UPD. Maternal isodisomy of the 16q24 region led to homozygosity for the MLYCD mutant allele, causing the patient's disease. These findings are relevant for genetic counselling of couples with a previously affected child, since the recurrence risk in future pregnancies is dramatically reduced by the finding of UPD. In addition, since the patient had none of the clinical manifestations previously associated with maternal UPD 16, this case provides no support for the existence of maternally imprinted genes on chromosome 16 with a major effect on phenotype. [ABSTRACT FROM AUTHOR]

We propose a bandwidth control method to increase or decrease the entire assigned upstream bandwidth by monitoring the queue length in order to prevent a drop in the throughput and an increase in the delay time when congestion is produced by the traffic generated by multiple users in a passive optical network (PON)-type optical access system for economically providing wideband multimedia services. The ability of the proposed method to avoid congestion, improve the Transmission Control Protocol (TCP) throughput, reduce the delays, and assure fairness between the TCP and User Datagram Protocol (UDP) traffic is demonstrated in computer simulations by applying the proposed method to the Broadband-PON (B-PON) system which complies with the ITU-T standard. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(7): 41– 55, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20374 [ABSTRACT FROM AUTHOR]

This paper introduces a general hybrid systems framework to model the flow of traffic in communication networks. The proposed models use averaging to continuously approximate discrete variables such as congestion window and queue size. Because averaging occurs over short time intervals, discrete events such as the occurrence of a drop and the consequent reaction by congestion control can still be captured. This modeling framework, thus, fills a gap between purely packet-level and fluid-based models, faithfully capturing the dynamics of transient phenomena and yet providing significant flexibility in modeling various congestion control mechanisms, different queueing policies, multicast transmission, etc, The modeling framework is validated by comparing simulations of the hybrid models against packet-level simulations. It is shown that the probability density functions produced by the ha-2 network simulator match closely those obtained with hybrid models. Moreover, a complexity analysis supports the observation that in networks with large per-flow bandwidths, simulations using hybrid models require significantly less computational resources than an-2 simulations. Tools developed to automate the generation and simulation of hybrid systems models are also presented. Their use is showcased in a study, which simulates TCP flows with different roundtrip times over the Abilene backbone. [ABSTRACT FROM AUTHOR]

Background and purpose:The uracil nucleotides UDP and UTP have been reported to activate P2Y2, P2Y4 and P2Y6 receptors to cause vasoconstriction. We have performed a comparative analysis of these receptors in endothelium-denuded smooth muscle from porcine isolated coronary and ear arteries, using pharmacological and molecular tools.Experimental approach:Tissue segments were used to construct non-cumulative concentration response curves for UTP and UDP, in the absence and presence of the P2 receptor antagonists PPADS or suramin. RT-PCR and immunoblot analyses were employed to define gene expression and immunoreactivity for P2Y2, P2Y4 and P2Y6 receptors.Key results:In the coronary artery, UTP-evoked contractile responses were reduced in the presence of suramin, but not PPADS, while the smaller responses to UDP were unaffected by either antagonist. In the ear artery, contractile responses to UDP were much smaller than those to UTP; responses to UTP were inhibited by both PPADS and suramin. RT-PCR suggested predominant expression of P2Y2 receptors in the coronary artery, while P2Y4 and P2Y6 receptor gene expression appeared equivalent in both tissues. Immunoblot analyses provided evidence for P2Y6 receptors in both tissues, with equivocal evidence of P2Y2 and P2Y4 receptor immunoreactivities.Conclusions and implications:We conclude that UTP-evoked contraction of porcine coronary artery smooth muscle appears to be predominantly P2Y2-mediated, while the ear artery appears to express a uracil nucleotide-sensitive P2 receptor(s) which fails to fit readily into the current classification.British Journal of Pharmacology (2007) 150, 604–612. doi:10.1038/sj.bjp.0707120; published online 29 January 2007 [ABSTRACT FROM AUTHOR]

Wireless multimedia studies have revealed that forward error correction (FEC) on corrupted packets yields better bandwidth utilization and lower delay than retransmissions. To facilitate FEC-based recovery, corrupted packets should not be dropped so that maximum number of packets is relayed to a wireless receiver's FEC decoder. Previous studies proposed to mitigate wireless packet drops by a partial checksum that ignored payload errors. Such schemes require modifications to both transmitters and receivers, and incur packet-losses due to header errors. In this paper, we introduce a receiver-based scheme which uses the history of active multimedia sessions to detect transmitted values of corrupted packet headers, thereby improving wireless multimedia throughput. Header detection is posed as the decision-theoretic problem of multihypothesis detection of known parameters in noise. Performance of the proposed scheme is evaluated using trace-driven video simulations on an 802.11b local area network. We show that header detection with application layer FEC provides significant throughput and video quality improvements over the conventional UDP/IP/802.11 protocol stack [ABSTRACT FROM PUBLISHER]

This paper considers control and estimation problems where the sensor signals and the actuator signals are transmitted to various subsystems over a network. In contrast to traditional control and estimation problems, here the observation and control packets may be lost or delayed. The unreliability of the underlying communication network is modeled stochastically by assigning probabilities to the successful transmission of packets. This requires a novel theory which generalizes classical control/estimation paradigms. The paper offers the foundations of such a novel theory. The central contribution is to characterize the impact of the network reliability on the performance of the feedback loop. Specifically, it is shown that for network protocols where successful transmissions of packets is acknowledged at the receiver (e.g., TCP-like protocols), there exists a critical threshold of network reliability (i.e., critical probabilities for the successful delivery of packets), below which the optimal controller fails to stabilize the system. Further, for these protocols, the separation principle holds and the optimal LOG controller is a linear function of the estimated state. In stark contrast, it is shown that when there is no acknowledgement of successful delivery of control packets (e.g.. UDP-like protocols), the LOG optimal controller is in general nonlinear. Consequently, the separation principle does not hold in this circumstance. [ABSTRACT FROM AUTHOR]

The cost savings and novel features associated with voice over IP (VoIP) are driving its adoption by service providers. Unfortunately, the Internet's best effort service model provides no quality of service guarantees. Because low latency and jitter are the key requirements for supporting high-quality interactive conversations, VoIP applications use UDP to transfer data, thereby subjecting themselves to quality degradations caused by packet loss and network failures. In this paper, we describe an architecture to improve the performance of such VoIP applications. Two protocols are used for localized packet loss recovery and rapid rerouting in the event of network failures. The protocols are deployed on the nodes of an application-level overlay network and require no changes to the underlying infrastructure. Experimental results indicate that the architecture and protocols can be combined to yield voice quality on par with the public switched telephone network [ABSTRACT FROM PUBLISHER]

Wireless networks beyond 2G aim at supporting real-time applications such as VolP. Before a user can start a VolP session, the end-user terminal has to establish the session using signaling protocols such as H.323 and session initiation protocol (SIP) in order to negotiate media parameters. The time interval to perform the session setup is called the session setup time. It can be affected by the quality of the wireless link, measured in terms of frame error rate (FER), which can result in retransmissions of packets lost and can lengthen the session setup time. Therefore, such protocols should have a session setup time optimized against loss. One way to do so is by choosing the appropriate retransmission timer and the underlying protocols. In this paper, we focus on SIP session setup delay and propose optimizing it using an adaptive retransmission timer. We also evaluate SIP session setup performances with various underlying protocols (transport control protocol (TCP), user datagram protocol (UDP), radio link protocols (RLPs)) as a function of the FER. For 19.2 Kbps channel, the SIP session setup time can be up to 6.12s with UDP and 7s with TCP when the FER is up to 10 percent. The use of RLP (1,2, 3) and RLP (1, 1, 1, 1, 1, 1) puts the session setup time down to 3.4s under UDP and 4s under TCP for the same FER and the same channel bandwidth. We also compare SIP and H.323 performances using an adaptive retransmission timer: SIP outperforms H.323, especially for a FER higher than 2 percent. [ABSTRACT FROM AUTHOR]

Abstract: Data acquisition in shot-based fusion experiments is characterized by a large amount of data collected within a short time. The stellarator experiment Wendelstein 7-X (W7-X) will produce a considerable higher amount of data in a continuous and steady-state operation within half an hour. Therefore, it is not sufficient to wait until all data has been acquired and stored in the database before being able to view and analyze data. Continuous and robust data transport is needed for (1) a distributed data monitoring system to visualize trends, (2) continuous data acquisition of data available at the network and (3) message signaling. The paper introduces a network channel concept covering a system-wide available data description, half sync/half async communication pattern, data serialization, identification and matching of data. It is focusing on the IP Multicast/UDP implementation for the data monitoring system and presents results of performance measurements. Suitability and limitations are discussed and an appropriate answer to the question “When is IP Multicast/UDP reliable?” is given. [Copyright &y& Elsevier]

Protocols in the transport layer are basically classified by the amount of reliability they offer. Adoption of customized protocol, wherein the user can select the level of reliability for the pertinent communication, finds importance specifically in situations of activation and/or information retrieval of/from a robotized system. The developed architecture, Variable Reliability Dataflow Protocol (VRDP), provides transmission accountability in a transparent way, wherein users can select the degree of reliable connection necessary for the application. [ABSTRACT FROM AUTHOR]

We propose a general framework based in the Gilbert model for cross-layer analysis of TCP and UDP over MIMO wireless systems. Our framework takes into consideration diverse system characteristics often difficult to express as a Gilbert model such as fading, space-time transmission schemes, modulation, channel coding and ARQ. We apply our framework to analyze the TCP performance of two representative MIMO systems, namely, the BLAST system and the orthogonal space-time block coded (STBC) system. In particular, we investigate the optimal information rate that maximizes the TCP throughput, the effect of Doppler on the optimal TCP throughput and the optimal channel coding rate for various modulations. We provide simulations results from the ns-2 network simulator to demonstrate the accuracy of the proposed analytical framework in characterizing the TCP performance. We further apply the framework to two additional cross-layer applications: the analysis of the buffer occupancy on the base station, and the analysis of CBR video transmission over MIMO systems. We show that while the optimal rate for maximum TCP throughput is far from the channel capacity, the optimal rate for error and delay-tolerant video transmission requires much higher rates, and so the physical layer should be aware and adapt to the type of application in order to increase the system performance. We also show that mobility benefits systems with larger buffers, especially for TCP, as the ARQ scheme is able to recover the shorter burst errors. In general, our investigation shows that the type of application plays a crucial role in the optimization of a wireless system, and that our modelling framework is useful for the cross-layer analysis and design of those systems. [ABSTRACT FROM PUBLISHER]

The pervasiveness and the seemingly unpopular nature of unidirectional data transfer has greatly necessitated the efforts of this paper. We investigated the performance of User Datagram Protocol (UDP) over IP-based wireline and wireless networks. The conceptual model was developed and tested using Network Simulator 2(NS2) and its bevaviour was monitored over the two networks. The results of the simulation in terms of effective throughput, packet drop/loss, and bandwidth utilization were presented. It reveals that UDP exhibits improved performance degradation on wired networks and that the high throughput is as a result of the fact that UDP does not have flow control protocol as it does not retransmit lost packets. [ABSTRACT FROM AUTHOR]

Abstract: Montelukast and pranlukast are orally active leukotriene receptor antagonists selective for the CysLT1 receptor. Conversely, the hP2Y1,2,4,6,11,12,13,14 receptors represent a large family of GPCRs responding to either adenine or uracil nucleotides, or to sugar-nucleotides. Montelukast and pranlukast were found to inhibit nucleotide-induced calcium mobilization in a human monocyte-macrophage like cell line, DMSO-differentiated U937 (dU937). Montelukast and pranlukast inhibited the effects of UTP with IC50 values of 7.7 and 4.3μM, respectively, and inhibited the effects of UDP with IC50 values of 4.5 and 1.6μM, respectively, in an insurmountable manner. Furthermore, ligand binding studies using [3H]LTD4 excluded the possibility of orthosteric nucleotide binding to the CysLT1 receptor. dU937 cells were shown to express P2Y2, P2Y4, P2Y6, P2Y11, P2Y13 and P2Y14 receptors. Therefore, these antagonists were studied functionally in a heterologous expression system for the human P2Y receptors. In 1321N1 astrocytoma cells stably expressing human P2Y1,2,4,6 receptors, CysLT1 antagonists inhibited both the P2Y agonist-induced activation of phospholipase C and intracellular Ca2+ mobilization. IC50 values at P2Y1 and P2Y6 receptors were <1μM. In control astrocytoma cells expressing an endogenous M3 muscarinic receptor, 10μM montelukast had no effect on the carbachol-induced rise in intracellular Ca2+. These data demonstrated that CysLT1 receptor antagonists interact functionally with signaling pathways of P2Y receptors, and this should foster the study of possible implications for the clinical use of these compounds in asthma or in other inflammatory conditions. [Copyright &y& Elsevier]

The growth of high-speed wide area networks (WANs) has enabled the emergence of new classes of data intensive, wide area computing applications, such as the remote analysis and exploration of data and distributed data mining. The de facto standard for reliable data transfers is the Transmission Control Protocol (TCP). Despite improvements in TCP over the years (to reduce overhead and achieve higher throughput), it is still a common experience for the end-to-end data rates of wide area data mining and data analysis applications to be inefficient. This paper introduces a library called SABUL (Simple Available Bandwidth Utilization Library) which merges features of UDP and TCP to produce a light-weight protocol with flow control, rate control and reliable transmission mechanisms that is designed for data intensive applications over wide area high performance networks. In this paper, we describe the library and give experimental evidence of its effectiveness. [ABSTRACT FROM AUTHOR]

Several novel UDP glycosyltransferase (UGT) genes, mainly UDP glucuronosyltransferases, have been identified in the human, mouse and rat genomes and in other mammalian species. This review provides an update of the UGT nomenclature to include these new genes and prevent the confusion that arises when the same gene is given different names. The new genes are named following previously established recommendations, taking into consideration evolutionary relatedness and the names already in general usage in the literature. The mammalian UGT gene superfamily currently has 117 members that can be divided into four families, UGT1, UGT2, UGT3 and UGT8. The 5-exon genes of the UGT1 family each contain a unique first exon, plus four exons that are shared between the genes; the exons 1 appear to have evolved by a process of duplication, leading to the synthesis of proteins with identical carboxyl-terminal and variable amino-terminal domains. Exon-sharing is also seen with the 6-exon UGT2A1 and UGT2A2 genes. However, UGT2A3 and those of the UGT2B (six exons), UGT3 (seven exons) and UGT8 gene families (five or six exons) do not share exons and most likely were derived by a process of duplication of all exons in the gene. Most UGT1 and UGT8 enzymes have been characterized in detail; however, the catalytic functions of the UGT3A enzymes and several UGT2 enzymes remain to be characterized. [ABSTRACT FROM AUTHOR]

In airways Cl- secretion is activated and Na+ absorption is inhibited when P2Y2 receptors are stimulated by ATP or UTP. Both nucleotides are subject to degradation to ADP and UDP by ecto-nucleotidases. Here we show that these metabolites change electrolyte transport by stimulation of P2Y6 receptors in mouse trachea. Immunohistochemistry confirmed luminal and basolateral expression of P2Y 6 receptors. In Ussing chamber experiments luminal ADP, UDP or the P2Y6 receptor agonist INS48823 induced both transient and persistent increase in short circuit currents (ISC). Activation of I SC was inhibited by the P2Y6 receptor blocker PPADS. The transient response was inhibited by DIDS, whereas the persistent I SC was inhibited by glibenclamide and by the protein kinase A (PKA) blocker H-89. Moreover, sustained activation of I SC by luminal UDP was inhibited by blocking basolateral K+ channels with 293B. Possible effects of diphosphates on P2Y1 or adenosine receptors were excluded by the inhibitors MRS2179 and 8-SPT, respectively. Inhibition of amiloride sensitive Na+ absorption was only seen after blocking basolateral K+ channels with 293B. In contrast, Cl- secretion activated by basolateral ADP or UDP was only transient and was blocked by the sk4 K+ channel blocker clotrimazole. In summary, activation of luminal P2Y6 receptors in the airways shifts electrolyte transport towards secretion by increasing intracellular Ca+ and activation of PKA. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Nucleotides like ATP and UTP act as potent extracellular signalling molecules. Released from sympathetic nerve endings as cotransmitters of noradrenaline or paracrine from nonexcitatory cells, they activate specific receptors (ion-gated P2X1-7 and G-protein-coupled P2Y1,2,4,6,11-15). Which of these subtypes, however, are able to modulate vasoconstriction in the kidney is unclear.Wild-type- and P2Y4-receptor-deficient mice kidneys were isolated and perfused with Krebs-Henseleit solution. Pressor responses to renal nerve stimulations (RNS) and added drugs were recorded. Release of endogenous noradrenaline was measured by HPLC.RNS (1-15?Hz) induced a frequency-dependent increase in the perfusion pressor (14.2±5.1-67.3±6.9?mmHg) and noradrenaline release (1.4±0.3-24.2±3.4?ng?g-1 kidney).Pressor responses to RNS were not (1-2?Hz) or only partially (5-15?Hz) blocked by thea-adrenoceptor antagonist phentolamine (1?µM). Combination of phentolamine and the P2-receptor blocker PPADS (5?µM) prevented RNS-induced pressor responses. The P2X1,3-receptor selective antagonist NF279 (10?µM) reduced RNS-induced pressor responses in a frequency-dependent manner.Perfusion of ATP, ADP, UTP, UDP anda,ß-meATP concentration dependently increased perfusion pressor with the following rank order of potencya,ß-meATP>ADP˜ATP˜UDP?UTP. NF279 (10?µM) reduceda,ß-meATP- (0.1?µM) (21.7±3.9%of control) but not UTP- (0.3?µM) (102.6±15.3%of control) induced pressor responses. No differences in nucleotide-induced effects were detected among wild-type and P2Y4-receptor knockout mice.Continuous perfusion ofa,ß-meATP (0.01?µM) potentiated UTP-, UDP- and ATP-?S-induced pressor responses.Neuronally and paracrine-released nucleotides evoked renal vasoconstriction by activation of P2X1,3- and P2Y6-like receptors in mice. Pretreatment with the P2X1,3-receptor agonista,ß-meATP potentiated P2Y6-like receptor-mediated vasoconstrictions.British Journal of Pharmacology (2005) 145, 66-74. doi:10.1038/sj.bjp.0706151 [ABSTRACT FROM AUTHOR]

A fundamental issue in real-time interactive voice transmissions over unreliable IF networks is the loss or late arrival of packets for playback. This problem is especially serious when transmitting low bit rate-coded speech with pervasive dependencies introduced. In this case, the loss or late arrival of a single packet will lead to the loss of subsequent dependent frames. We study end-to-end loss-concealment schemes for ensuring high quality in playback. We propose a novel multiple description-coding method for concealing packet losses in transmitting low bit rate-coded speech. Based on high correlations observed in linear predictor parameters-in the form of Line Spectral Pairs (LSPs)-of adjacent frames, we generate multiple descriptions in senders by interleaving LSPs, and reconstruct lost LSPs in receivers by linear interpolations. As excitation codewords have low correlations, we further enlarge the segment size for excitation generation and replicate excitation codewords in all the descriptions in order to maintain the same transmission bandwidth. Our proposed scheme can be extended easily to more than two descriptions and can adapt its number of descriptions dynamically to network-loss conditions. Experimental results on FS-1016 CELP, ITU G.723.1, and FS MELP coders show good performance of our scheme. [ABSTRACT FROM PUBLISHER]

In this paper the transmission of JPEG2000 and Motion JPEG2000 codestreams in 802.11 WLAN environment is analyzed. The issues related to the transmission of JPEG2000, using non reliable protocols as UDP-RTP, are investigated and a proper protection scheme for dealing with such an environment is presented. along with the obtained performance with different systems parameters. The proposed technique addresses a wide range of multimedia applications such as wireless PC to Digital Projector multimedia presentations, point to multipoint digital slide projection, wireless video-surveillance systems. [ABSTRACT FROM AUTHOR]

Quality-delay trade-offs can be made in transmitting subband-coded images in the Internet by using either the TCP or the UDP protocol. Delivery by TCP gives superior decoding quality but with very long delays when the network is unreliable, whereas delivery by UDP has negligible delays but with degraded quality when packets are lost. Although images are delivered primarily by TCP today, we study in this paper the use of UDP to deliver multi-description reconstruction-based subband-coded images and the reconstruction of missing information at the receiver based on information received. We first determine empirically the interleaving factors that should be used in order to keep the probability of unrecoverable packet losses sufficiently small. Next, we propose a joint sender-receiver approach for designing transforms in multi-description subband coding. In the receiver, we use a simple interpolation-based reconstruction algorithm, as sophisticated concealment techniques cannot be employed in practice. In the sender, we design an optimized reconstruction-based subband transform (ORB-ST), with an objective of minimizing the mean squared error, assuming that some of the descriptions are lost and that the missing information is reconstructed by simple averaging at the destination. Experimental results show that our proposed ORB-ST performs well in real Internet tests, and UDP delivery of MDC images is an attractive alternative to TCP delivery. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the throughput and energy efficiency performance of user datagram protocol (UDP) using linear, binary exponential, and geometric backoff algorithms at the link layer (LL) on point-to-point wireless fading links. Using a first-order Markov chain representation of the packet success/failure process on fading channels, we derive analytical expressions for throughput and energy efficiency of UDP/LL with and without LL backoff. The analytical results are verified through simulations. We also evaluate the mean delay and delay variation of voice packets and energy efficiency performance over a wireless link that uses UDP for transport of voice packets and the proposed backoff algorithms at the LL. We show that the proposed LL backoff algorithms achieve energy efficiency improvement of the order of 2-3 dB compared to LL with no backoff, without compromising much on the throughput and delay performance at the UDP layer. Such energy savings through protocol means will improve the battery life in wireless mobile terminals. [ABSTRACT FROM PUBLISHER]