Search

Although human cytomegalovirus (HCMV) primary infection is generally asymptomatic, in immune-compromised patients HCMV increases morbidity and mortality. As a member of the betaherpesvirus family, in vivo studies of HCMV are limited due to its species specificity. CMVs from other species are often used as surrogates to express HCMV genes/proteins or used as models for inferring HCMV protein function in humans. Using innovative experiments, these animal models have answered important questions about CMV's life cycle, dissemination, pathogenesis, immune evasion, and host immune response. This chapter provides CMV biologists with an overview of the insights gained using these animal models. Subsequent chapters will provide details of the specifics of the experimental methods developed for each of the animal models discussed here. [ABSTRACT FROM AUTHOR]

Of the many research challenges posed by human cytomegalovirus latency, perhaps the most notable is the requirement for primary hematopoietic cell culture. Culturing hematopoietic subpopulations while maintaining physiological relevance must be given utmost consideration. We describe a long-standing primary CD34+ hematopoietic progenitor cell (HPCs) system as an experimental model to study human cytomegalovirus (HCMV) latency and reactivation. Key aspects of our model include infection of primary human CD34+ HPCs prior to ex vivo expansion, maintenance of undifferentiated cells in a long-term culture with a stromal cell support, and an assay to quantitate infectious centers produced prior to and following a reactivation stimulus. Our method offers a unique way to quantitatively assess HCMV latency and reactivation to study the contribution of viral and host genes in latency and reactivation. [ABSTRACT FROM AUTHOR]

The extensive tropism of human cytomegalovirus (HCMV) results in the productive infection of multiple cell types within the human host. However, infection of other cell types, such as undifferentiated cells of the myeloid lineage, gives rise to nonpermissive infections. This has been used experimentally to model latent infection which is known to be established in the pluripotent CD34+ hematopoietic progenitor cell population resident in the bone marrow in vivo. The absence of a tractable animal model for studies of HCMV has resulted in a number of laboratories employing experimental infection of cells in vitro to simulate both HCMV lytic and latent infection. Herein, we will focus on the techniques used in our laboratory for the isolation and use of primary cells to study aspects of HCMV latency, reactivation, and lytic infection. [ABSTRACT FROM AUTHOR]

We describe a primary neuronal culture system suitable for molecular characterization of herpes simplex virus type 1 (HSV-1) infection, latency, and reactivation. While several alternative models are available, including infections of live animal and explanted ganglia, these are complicated by the presence of multiple cell types, including immune cells, and difficulties in manipulating the neuronal environment. The highly pure neuron culture system described here can be readily manipulated and is ideal for molecular studies that focus exclusively on the relationship between the virus and host neuron, the fundamental unit of latency. As such it allows for detailed investigations of both viral and neuronal factors involved in the establishment and maintenance of HSV-1 latency and in viral reactivation induced by defined stimuli. [ABSTRACT FROM AUTHOR]

DNA vaccines have been licensed in veterinary medicine and have promise for humans. This format is relatively immunogenic in mice and guinea pigs, the two principle HSV-2 animal models, permitting rapid assessment of vectors, antigens, adjuvants, and delivery systems. Limitations include the relatively poor immunogenicity of naked DNA in humans and the profound differences in HSV-2 pathogenesis between host species. Herein, we detail lessons learned over the last few years investigating candidate DNA vaccines in the progesterone-primed female mouse vaginal model of HSV-2 infection as a guide to investigators in the field. [ABSTRACT FROM AUTHOR]

Two important components to a useful strategy to examine viral gene regulation in vivo are (1) a highly efficient protocol to generate viral mutants that limits undesired mutation and retains full replication competency in vivo and (2) an efficient system to detect and quantify viral promoter activity in rare cells in vivo. Our strategy and protocols for generating, characterizing, and employing HSV viral promoter/reporter mutants in vivo are provided in this two-part chapter. [ABSTRACT FROM AUTHOR]

Wireless sensor networks have been widely used in the monitoring application. In this paper we shed some lights on several issues in building a complete system for using wireless sensor networks for practical highway long distance tunnel environment monitoring application. From the engineering perspective it is necessary to consider the nodes deployment and from the application perspective it is necessary to meet the performance requirements. Energy conservation, topology and coverage are some important factors need to be taken full consideration for the purpose of providing safe friendly vehicle running environment. Still more deserve to discuss for brighter future of the tracking and monitoring foreground. [ABSTRACT FROM AUTHOR]

Carbon Nanotubes (CNTs), Graphene Nanoribbons (GNRs), and Optical Interconnects and carbon nanotubes present promising options for replacing the existing Cu-based global/semiglobal and local wires. In this chapter, the performance of these novel interconnects is quantified and compared with Cu/low-Κ wires for future high-performance integrated circuits. For a local wire, a CNT bundle exhibits a smaller latency than Cu for a given geometry. In addition, by leveraging the superior electromigration properties of CNT and optimizing its geometry, the latency advantage can be further amplified. GNRs outperforms Cu wire below the width of 7nm. For semiglobal and global wires, both optical and CNT options are compared with Cu in terms of latency, energy efficiency/power dissipation, and bandwidth density. The above trends are studied with technology node. In addition, for a future technology node, we compare the relationship between bandwidth density, power density, and latency, thus alluding to the latency and power penalty to achieve a given bandwidth density. [ABSTRACT FROM AUTHOR]

Cadaveric studies measuring up to 63% narrowing of the stenotic spine with extension suggests that intraspinal conductions in the cauda equina might be delayed by extension. In this chapter, we examine delays in H-reflexes brought about by extension and then use this delay as an estimate of the clinical significance of patients΄ stenosis. This is useful in determining how great a factor the stenosis is when it is accompanied by a herniated disc, for it helps clinicians decide which of two conditions should be the chief focus of therapy. [ABSTRACT FROM AUTHOR]

4 design case studies using the 2.5-D integration scheme are presented in this chapter. The first 3 designs, a crossbar circuit, a Rambus DRAM, and a reconfigurable data-path (PipeRench), are re-designed by exploiting fine-grain inter-chip interconnects. The 4th design study involves a 3-D stacked CPU/memory system. The above design cases studies validate the potential of the 2.5-D integration paradigm from a performance point of view. [ABSTRACT FROM AUTHOR]

Network-on-Chip (NoC) is viewed as a viable substitution for traditional interconnection networks to achieve high performance, communication efficiency and reliability in complex VLSI architectures at deep sub micron. Achieving high performance, power efficiency with optimum area is a target for any routing algorithm in NoC. In this paper, we propose a novel routing scheme named `ERA΄, which offers higher throughput with controlled delays while remaining power aware. ERA is an adaptive routing algorithm, which avoids congestion and tends to minimize the hot spots in the network. Unlike other existing algorithms, the proposed algorithm does not require any virtual channels to avoid deadlocks. We compare our algorithm with XY and OE on the basis of a performance metric called `power performance factor΄ for different traffic patterns and injection models. Our results show that ERA performs better than these two algorithms. [ABSTRACT FROM AUTHOR]

Online classification learners operating under concept drift can be subject to latency in examples arriving at the training base. A discussion of latency and the related notion of example filtering leads to the development of an example life cycle for online learning (OLLC). Latency in a data stream is modelled in a new Example Life-cycle Integrated Simulation Environment (ELISE). In a series of experiments, the online learner algorithm CD3 is evaluated under several drift and latency scenarios. Results show that systems subject to large random latencies can, when drift occurs, suffer substantial deterioration in classification rate with slow recovery. [ABSTRACT FROM AUTHOR]

Due to the large-scale ad hoc deployments and wireless interference, data aggregation is a fundamental but time consuming task in wireless sensor networks. This paper focuses on the latency of data aggregation. Previously, it has been proved that the problem of minimizing the latency of data aggregation is NP-hard [1]. Using maximum independent set and first fit algorithms, in this study we design a scheduling algorithm, Peony-tree-based Data Aggregation (PDA), which has a latency bound of 15R + ∆− 15, where R is the network radius (measured in hops) and ∆ is the maximum node degree. We theoretically analyze the performance of PDA based on different network models, and further evaluate it through extensive simulations. Both the analytical and simulation results demonstrate the advantages of PDA over the state-of-art algorithm in [2], which has a latency bound of 23R + ∆− 18. [ABSTRACT FROM AUTHOR]

Shared last level cache is crucial to performance. However, multi-thread program model incurs serious contention in shared cache. In this paper, to reduce average cache access latency, we propose two schemes. First, an implicitly dynamic cache partitioning scheme, i.e. block agglutinating. The purpose is to isolate conflicting data blocks. Second, a novel hardware buffer, called thread owned block cache, i.e. TOB Cache. The purpose is to store conflicting data blocks. Extensive analysis of the proposed schemes with Splash2 benchmarks and Bioinformatics workloads is performed using a cycle accurate many-core simulator. Experimental results show that the proposed schemes make conflict miss rate of shared cache reduced by 40% compared to traditional shared cache. Compared with victim cache, average load latency of shared cache and primary data cache is reduced by about 26% and 12%, respectively; primary data cache miss penalties are reduced by about 14%, and IPC is improved by 17%. [ABSTRACT FROM AUTHOR]

In this paper we present a benchmark tool called PI-ping that can be used to compare real-time performance of operating systems. It uses two types of processes that are common in operating systems – interactive tasks demanding low latencies and also processes demanding high CPU utilization. Most operating systems have to perform well in both conditions and the goal is to achieve the highest throughput when keeping the latencies within a reasonable interval. PI-ping measures the latencies of an interactive process when the system is under heavy computational load. Using PI-ping benchmark tool we are able to compare different operating systems and we attest the functionality of it using two very common operating systems - Linux and FreeBSD. [ABSTRACT FROM AUTHOR]

Mattern΄s GVT algorithm is a time management algorithm that helps achieve the synchronization in parallel and distributed systems. This algorithm uses ring structure to establish cuts C1 and C2 to calculate the GVT. The latency of calculating the GVT is vital in parallel/distributed systems which is extremely high if calculated using this algorithm. However, using synchronous barriers with the Matterns algorithm can help improving the GVT computation process by minimizing the GVT latency. In this paper, we incorporate the butterfly barrier to employ two cuts C1 and C2 and obtain the resultant GVT at an affordable latency. Our analysis shows that the proposed GVT computation algorithm significantly improves the overall performance in terms of memory saving and latency. [ABSTRACT FROM AUTHOR]

In recent years a number of TCP variants have emerged to optimise some aspect of data transport where high delay-bandwidth product paths are common. We evaluate a different scenario - latency-sensitive UDP-based traffic sharing a consumer-grade `broadband΄ link with one or more TCP flows. In particular we compare Linux implementations of NewReno, H-TCP and CUBIC. We find that dynamic latency fluctuations induced by each TCP variant is a more significant differentiator than `goodput΄ (useful throughput), and that CUBIC induces far more latency than either H-TCP or NewReno when multiple TCP flows are active concurrently. This potential for `collateral damage΄ should influence future efforts to re-design TCP for widespread deployment. [ABSTRACT FROM AUTHOR]

A network of many sensors and a base station that are deployed over a region is considered. Each sensor has a transmission range, a interference range, and a carrier sensing range, which is r, αr, and βr, respectively. In this paper, we study the minimum latency conflict-aware many-to-one data aggregation scheduling problem: Given locations of sensors along with a base station, a subset of sensors, and parameters r,α, and β, find a schedule in which the data of each sensor in the subset can be transmitted to the base station with no conflicts, such that the latency is minimized. We designed an nearly a constant ratio approximation algorithm and a heuristic algorithm for the problem. Extensive simulations have been done to show the performances of the two algorithms. [ABSTRACT FROM AUTHOR]

Design of a MAC protocol for a wireless sensor network requires ensuring efficient utilization of energy and minimization of interference and latency. We present QDMAC, a MAC protocol designed to excel on these parameters for query based wireless sensor networks. The paper includes various phases of the proposed protocol viz. allotment of mote-ids, formation of convergecast tree topology, allocation of collision free schedules to the motes and the technique for maintaining the time synchronization in the network. The protocol has been implemented and tested on a test-bed of twenty micaz motes. The implementation of the protocol is found to be satisfactory. [ABSTRACT FROM AUTHOR]

Wireless Sensor Network is Multihop Self-configuring Wireless Network consisting of sensor nodes. The patterns of movement of nodes can be classified into different mobility models and each is characterized by their own distinctive features. The significance of this study is that there has been very limited investigations of the effect of mobility models on routing protocol performance such as Packet Delivery Ratio, Throughput and Latency in Wireless Sensor Network. In this paper, we have considered the influence of pursue group and random based entity mobility models on the performance of Ad Hoc On-Demand Distance Vector Routing Protocol (AODV) routing protocol. The simulation results show that Pursue Group Mobility model is better than Random Based Entity model. [ABSTRACT FROM AUTHOR]

Recently a large number of multimedia content is streamed to millions of users through peer-to-peer networks. Most of them are based on an unstructured mesh-based topology. It results to a long end-to-end delay. Based on this consideration, this paper proposed a novel topology construction approach, LayerP2P, to construct a low-latency structured overlay for live streaming. It organize peers into a multi-layer mesh-based topology. Since the maximum relay hops in the overlay are bounded by the number of layer, the average end-to-end delay is cut down. At the same time, the overlay keeps resilient by self-organized peers in a decentralized way. Experiments carried out over a simulated network of up to 500 peers illustrate the effectiveness of our approach. [ABSTRACT FROM AUTHOR]

Chapter 9 of the book "Journey Across the Life Span" is presented. It describes the physical characteristics common to school-age children. It explains the psychosocial task identified by psychologist Erik Erikson for the school-age period. It discusses the cognitive levels of functioning during the school-age period and offers information about moral development in school-age children.

The problem of transmission scheduling over a correlated time-varying wireless channel is formulated as a Constrained Markov Decision Process. The model includes a transmission buffer and finite state Markov model for time-varying radio channel and incoming traffic. The resulting cross-layer optimization problem is formulated to minimize the transmission cost under the constraint on a buffer cost such as the transmission delay. Under the assumptions on submodularity and convexity of the cost function it is shown that the optimal randomized policy is monotonically increasing with the increase of the buffer state. Furthermore, the influence of the channel and traffic correlation matrices on the optimal transmission cost is investigated. It is shown that comparison between optimal transmission costs of two different channels can be performed by considering the stochastic dominance relation of their conditional probability distributions. As an example of this result, channels with smaller scattering and the same mean can achieve smaller average transmission cost for the same average buffer cost. [ABSTRACT FROM AUTHOR]