Search results for "outer"
showing 10 items of 252 documents
Peripherin-2 couples rhodopsin to the CNG channel in outer segments of rod photoreceptors.
2014
Outer segments (OS) of rod photoreceptors are cellular compartments specialized in the conversion of light into electrical signals. This process relies on the light-triggered change in the intracellular levels of cyclic guanosine monophosphate (cGMP), which in turn controls the activity of cyclic nucleotide-gated (CNG) channels in the rod OS plasma membrane. The rod CNG channel is a macromolecular complex that in its core harbors the ion-conducting CNGA1 and CNGB1a subunits. To identify additional proteins of the complex that interact with the CNGB1a core subunit we applied affinity purification of mouse retinal proteins followed by mass spectrometry. In combination with in vitro and in viv…
Differential expression and interaction with the visual G-protein transducin of centrin isoforms in mammalian photoreceptor cells.
2004
Photoisomerization of rhodopsin activates a heterotrimeric G-protein cascade leading to closure of cGMP-gated channels and hyperpolarization of photoreceptor cells. Massive translocation of the visual G-protein transducin, Gt, between subcellular compartments contributes to long term adaptation of photoreceptor cells. Ca(2+)-triggered assembly of a centrin-transducin complex in the connecting cilium of photoreceptor cells may regulate these transducin translocations. Here we demonstrate expression of all four known, closely related centrin isoforms in the mammalian retina. Interaction assays revealed binding potential of the four centrin isoforms to Gtbetagamma heterodimers. High affinity b…
AQM generalized nyquist stability in multiple bottleneck networks
2005
Abstract The influence of multiple bottlenecks on the stability of Active Queue Management (AQM) controllers, usually configured on a single bottleneck basis is discussed. We consider a network scenario where RED is configured at each router according to previously developed control theoretic techniques. These configuration rules assure stability in a single bottleneck scenario. We show that instability may arise when two links become congested. We justify this result through a multiple bottleneck model using the Generalized Nyquist stability criterion.
Packet management techniques for measurement based end-to-end admission control in IP networks
2000
End-to-end Measurement Based connection Admission Control (EMBAC) mechanisms have been proposed to support real-time flows quality of service requirements over a Differentiated Services Internet architecture. The EMBAC basic idea is to decentralize the admission control decision, by requiring each individual user to probe the network path during flow setup, and by basing the accept/reject decision on the probing traffic statistics measured at the destination. In conformance with the differentiated services framework, routers are oblivious to individual flows and only need to serve data packets with a higher priority than probing traffic. In this paper, we build upon the observation that som…
Cost-Efficient On-Chip Routing Implementations for CMP and MPSoC Systems
2011
[EN] The high-performance computing domain is enriching with the inclusion of networks-on-chip (NoCs) as a key component of many-core (CMPs or MPSoCs) architectures. NoCs face the communication scalability challenge while meeting tight power, area, and latency constraints. Designers must address new challenges that were not present before. Defective components, the enhancement of application-level parallelism, or power-aware techniques may break topology regularity, thus, efficient routing becomes a challenge. This paper presents universal logic-based distributed routing (uLBDR), an efficient logic-based mechanism that adapts to any irregular topology derived from 2-D meshes, instead of usi…
A Novel Fault-Tolerant Routing Technique for Mesh-of-Tree based Network-on-Chip Design
2018
Due to the increase in the number of processing elements in System-on-Chips (SoCs), communication between the cores is becoming complex. A solution to this issue in SoCs gave rise to a new paradigm called Network-on-Chips (NoCs). In NoCs, communication between different cores is achieved using packet based switching techniques. In the deep sub-micron technology, NoCs are more susceptible to different kinds of faults which can be transient, intermittent and permanent. These faults can occur at any component of NoCs. This paper presents a novel Fault-Tolerant Routing (FTR) technique for Mesh-of-Tree (MoT) topology in the presence of router faults. The proposed technique is compared with routi…
Fault Tolerant Routing Methodology for Mesh-of-Tree based Network-on-Chips using Local Reconfiguration
2018
Increase in the processing elements in a System-on- Chip (SoC) has led to an increasing complexity between the cores in the entire network. This communication bottleneck led to rise in the new paradigm called Network-on-Chip (NoC). These NoC are very much susceptible to various types of faults which can be transient, intermittent or permanent. This paper presents a fault-tolerant routing technique which can route the packets from a source to a destination in presence of permanent faults in the leaf routers of Mesh-of-Tree topology where cores are connected. This is achieved by using reconfiguration in the local ports of the leaf routers by inserting multiplexers as a layer between the leaf …
Algorithmic Complexity Vulnerability Analysis of a Stateful Firewall
2016
Algorithmic complexity vulnerabilities are an opportunity for an ad-versary to conduct a sophisticated kind of attack i.e. on network infrastructure services. Such attacks take advantage of worst case time or space complexity of algorithms implemented on devices in their software. In this paper we address potential risks introduced by such algorithmic behavior in computer networks in particular on a stateful firewall. First we introduce the idea and theoretical background for the attack. We then describe in full detail a successfully con-ducted attack which takes advantage of the worst case computational complexi-ty of O(n2) of a hash table data structure used to store active sessions. The …
An API for Advanced Traffic Control in Diffserv Routers
2003
Distributed per-flow admission control is a promising solution for Differentiated Services networks. Its deployment in DiffSery domains requires the ability to suitably configure, in each network router, low-level packet forwarding mechanisms, such as packet dropping algorithms driven by traffic measurements. In this paper we first show that performance effectiveness is achieved by means of non traditional configuration of the forwarding mechanisms. Hence, we propose a modular Application Program Interface that allows to flexibly and adaptively configure the forwarding/dropping behavior associated to a router’s output queue, well beyond the traditional RED/RIO active queue management scheme…
About the stability of active queue management mechanisms
2004
In this paper, we discuss the influence of multiple bottlenecks on the stability of active queue management (AQM) controllers, usually configured on a single bottleneck basis. To see this, we consider a network scenario where RED is configured at each router according to previously developed control theoretic techniques. These configuration rules assure stability in a single bottleneck scenario. Yet, we show that instability may arise when two links become congested. We justify this result through a multiple bottleneck model.