An Efficient Queueing Policy for Input-Buffered Packet Switches

An efficient self-adaptive packet queueing policy, called Queueing with Output Address Grouping (QOAG), is proposed for optimizing the performance of an input buffered packet switch. Each input port of the N×N switch under consideration has Q queues and each queue has B packet buffers, where 1<Q<N. Using QOAG, a packet arriving at an input port is assigned to the queue which has some backlog packets with the same output address as that of the new packet. If the output address of the new packet is different from all current buffered packets in all queues, it is assigned to the shortest queue. The performance of QOAG is compared with the Odd-Even queueing policy of Kolias and Kleinrock (see Proceedings of IEEE ICC '96, p.1674-79, 1996) by simulations. The Zipf distribution version II is used to model the non-uniform packet output distributions. We found that for a 16×16 switch with B=20 buffers at each queue and input load p=0.7, the mean packet delays are 58.1 and 91.2 time slots and the mean throughputs are 0.474 and 0.355 for using QOAG and Odd-Even queueing respectively. This represents a 57% cut in mean packet delay and 25% increase in throughput when QOAG is used.published_or_final_versio

Scheduling algorithms for input-queued switches with virtual output queueing

A set of packet scheduling algorithms are proposed for improving the performance of Iterative Longest Port First (iLPF) algorithm in [1] for Virtual Output Queueing Switch. In our proposed algorithms, scheduling priority is given according to different criteria that include input port occupancy, output port occupancy and critical port in VOQ. One of our proposed algorithm, called Longest Input Port First with Throughput Maximization (LIPF with TM), gives significant performance improvement in mean packet delay and throughput when compared with iLPF. We found that for a 16 × 16 switch with input load p = 0.85, the mean packet delay is 7.08 slots for iLPF and 3.21 slots for LIPF with TM. This represents a 55% cut in mean packet delay.published_or_final_versio

Lookahead scheduling algorithm for input-buffered packet switches

An analytical model for evaluating the performance of a packet scheduling algorithm, called lookahead scheduling, is proposed in this paper. Using lookahead scheduling, each input port of a switch has B packet buffers. A packet arrives at an input port is scheduled for conflict-free transmission for up to B time slots in advance. If it cannot be scheduled for transmission in the next B slots, the packet is immediately discarded for having more room for the packets arrived later on. Based on a set of recursive equations for obtaining buffer occupancy and probability that a packet cannot be placed into a buffer, analytical expressions for switch throughput, packet loss probability and mean packet delay are derived. Analytical results are then compared with the simulation results and good agreement is found.published_or_final_versio

Evaluation of Phage Display Discovered Peptides as Ligands for Prostate-Specific Membrane Antigen (PSMA)

The aim of this study was to identify potential ligands of PSMA suitable for further development as novel PSMA-targeted peptides using phage display technology. The human PSMA protein was immobilized as a target followed by incubation with a 15-mer phage display random peptide library. After one round of prescreening and two rounds of screening, high-stringency screening at the third round of panning was performed to identify the highest affinity binders. Phages which had a specific binding activity to PSMA in human prostate cancer cells were isolated and the DNA corresponding to the 15-mers were sequenced to provide three consensus sequences: GDHSPFT, SHFSVGS and EVPRLSLLAVFL as well as other sequences that did not display consensus. Two of the peptide sequences deduced from DNA sequencing of binding phages, SHSFSVGSGDHSPFT and GRFLTGGTGRLLRIS were labeled with 5-carboxyfluorescein and shown to bind and co-internalize with PSMA on human prostate cancer cells by fluorescence microscopy. The high stringency requirements yielded peptides with affinities KD∼1 μM or greater which are suitable starting points for affinity maturation. While these values were less than anticipated, the high stringency did yield peptide sequences that apparently bound to different surfaces on PSMA. These peptide sequences could be the basis for further development of peptides for prostate cancer tumor imaging and therapy. © 2013 Shen et al

Annotation and query of tissue microarray data using the NCI Thesaurus

<p>Abstract</p> <p>Background</p> <p>The Stanford Tissue Microarray Database (TMAD) is a repository of data serving a consortium of pathologists and biomedical researchers. The tissue samples in TMAD are annotated with multiple free-text fields, specifying the pathological diagnoses for each sample. These text annotations are not structured according to any ontology, making future integration of this resource with other biological and clinical data difficult.</p> <p>Results</p> <p>We developed methods to map these annotations to the NCI thesaurus. Using the NCI-T we can effectively represent annotations for about 86% of the samples. We demonstrate how this mapping enables ontology driven integration and querying of tissue microarray data. We have deployed the mapping and ontology driven querying tools at the TMAD site for general use.</p> <p>Conclusion</p> <p>We have demonstrated that we can effectively map the diagnosis-related terms describing a sample in TMAD to the NCI-T. The NCI thesaurus terms have a wide coverage and provide terms for about 86% of the samples. In our opinion the NCI thesaurus can facilitate integration of this resource with other biological data.</p

Inhibitors of inflammation and endogenous surfactant pool size as modulators of lung injury with initiation of ventilation in preterm sheep

<p>Abstract</p> <p>Background</p> <p>Increased pro-inflammatory cytokines in tracheal aspirates correlate with the development of BPD in preterm infants. Ventilation of preterm lambs increases pro-inflammatory cytokines and causes lung inflammation.</p> <p>Objective</p> <p>We tested the hypothesis that selective inhibitors of pro-inflammatory signaling would decrease lung inflammation induced by ventilation in preterm newborn lambs. We also examined if the variability in injury response was explained by variations in the endogenous surfactant pool size.</p> <p>Methods</p> <p>Date-mated preterm lambs (n = 28) were operatively delivered and mechanically ventilated to cause lung injury (tidal volume escalation to 15 mL/kg by 15 min at age). The lambs then were ventilated with 8 mL/kg tidal volume for 1 h 45 min. Groups of animals randomly received specific inhibitors for IL-8, IL-1, or NF-κB. Unventilated lambs (n = 7) were the controls. Bronchoalveolar lavage fluid (BALF) and lung samples were used to quantify inflammation. Saturated phosphatidylcholine (Sat PC) was measured in BALF fluid and the data were stratified based on a level of 5 μmol/kg (~8 mg/kg surfactant).</p> <p>Results</p> <p>The inhibitors did not decrease the cytokine levels or inflammatory response. The inflammation increased as Sat PC pool size in BALF decreased. Ventilated lambs with a Sat PC level > 5 μmol/kg had significantly decreased markers of injury and lung inflammation compared with those lambs with < 5 μmol/kg.</p> <p>Conclusion</p> <p>Lung injury caused by high tidal volumes at birth were decreased when endogenous surfactant pool sizes were larger. Attempts to decrease inflammation by blocking IL-8, IL-1 or NF-κB were unsuccessful.</p

Lineage Divergence and Historical Gene Flow in the Chinese Horseshoe Bat (Rhinolophus sinicus)

PMCID: PMC3581519This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited