On Stress of a Vertex in a Graph

The stress of a vertex in a graph is the number of geodesics passing through it (A. Shimbel, 1953). A graph is $k$-stress regular if stress of each of its vertices is $k$. In this paper, we investigate some results and compute stress of vertices in some standard graphs and give a characterization of graphs with all vertices of zero stress except for one. Also we compute stress of vertices in graphs of diameter 2 and in the corona product $K_m \circ G$. Further we prove that any strongly regular graph is stress regular and characterize $k$-stress regular graphs for $k=0,1,2$.Comment: 11 pages, 12 figures, accepted for publication in Palestine Journal of Mathematic

Utilisation of flyash as cement replacement material to produce high performance concrete

Disposal of fly ash, a waste product from thermal power plants, is a major problem in India.Many R&D and academic institutions are actively involved in the effective utilisation of flyash in Civil Engineering applications. The Structural Engineering Research Centre (SERC),Chennai has carried out extensive research on utilisation of fly ash in concrete as partial cement replacement material (CRM) since 1975 . Recently, SERC has carried out extensive R&D work on development of High Performance Concrete (HPC) mixes using flyash(FA),ground granulated blast furnace slag(GGBS) and silica fume(SF) as mineral dmixtures,especially to improve the durability characteristics of cement concrete. This paper presents the mechanical and urability properties of different HPC mixes containing fly ash. HPCs using flyash as mineral admixture have been used to evelop precast concrete products such as, non-pressure pipes and heavy duty paver blocks and these developments are eported in this paper

Circulating tumor cells criteria (CyCAR) versus standard RECIST criteria for treatment response assessment in metastatic colorectal cancer patients

The use of circulating tumor cells (CTCs) as indicators of treatment response in metastatic colorectal cancer (mCRC) needs to be clarified. The objective of this study is to compare the Response Evaluation Criteria in Solid Tumors (RECIST) with the Cytologic Criteria Assessing Response (CyCAR), based on the presence and phenotypic characterization of CTCs, as indicators of FOLFOX–bevacizumab treatment response. We observed a decrease of CTCs (42.8 vs. 18.2%) and VEGFR positivity (69.7% vs. 41.7%) after treatment. According to RECIST, 6.45% of the patients did not show any clinical benefit, whereas 93.55% patients showed a favorable response at 12 weeks. According to CyCAR, 29% had a non-favorable response and 71% patients did not. No significant differences were found between the response assessment by RECIST and CyCAR at 12 or 24 weeks. However, in the multivariate analysis, RECIST at 12 weeks and CyCAR at 24 weeks were independent prognostic factors for OS (HR: 0.1, 95% CI 0.02–0.58 and HR: 0.35, 95% CI 0.12–0.99 respectively). CyCAR results were comparable to RECIST in evaluating the response in mCRC and can be used as an alternative when the limitation of RECIST requires additional response analysis techniques.This work was supported by Roche Spain and a Ph.D. grant from the University of Granada

Allele-specific RNA interference prevents neuropathy in Charcot-Marie-Tooth disease type 2D mouse models.

Gene therapy approaches are being deployed to treat recessive genetic disorders by restoring the expression of mutated genes. However, the feasibility of these approaches for dominantly inherited diseases - where treatment may require reduction in the expression of a toxic mutant protein resulting from a gain-of-function allele - is unclear. Here we show the efficacy of allele-specific RNAi as a potential therapy for Charcot-Marie-Tooth disease type 2D (CMT2D), caused by dominant mutations in glycyl-tRNA synthetase (GARS). A de novo mutation in GARS was identified in a patient with a severe peripheral neuropathy, and a mouse model precisely recreating the mutation was produced. These mice developed a neuropathy by 3-4 weeks of age, validating the pathogenicity of the mutation. RNAi sequences targeting mutant GARS mRNA, but not wild-type, were optimized and then packaged into AAV9 for in vivo delivery. This almost completely prevented the neuropathy in mice treated at birth. Delaying treatment until after disease onset showed modest benefit, though this effect decreased the longer treatment was delayed. These outcomes were reproduced in a second mouse model of CMT2D using a vector specifically targeting that allele. The effects were dose dependent, and persisted for at least 1 year. Our findings demonstrate the feasibility of AAV9-mediated allele-specific knockdown and provide proof of concept for gene therapy approaches for dominant neuromuscular diseases

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Relationships Among Different Models for Discrete-Time Queues

Abstract: Many small scale telecommunication networks operate in a slotted mode with constant data packet sizes. Some of these systems have only modest hardware and hence, queuing performance is an important issue. Performance analysis of slotted systems requires more than simply obtaining the performance figures of discrete-time Markov chains. This paper elucidates the importance of characterizing the timing and synchronization details required to correctly formulate the Markov chain and evaluate corresponding performance figures. Two distinct Markov chains are identified in such analysis of any slotted system. The events causing different transitions between the system states are systematically developed for both Markov chains. Relationships between time-averaged performance figures and corresponding expectations of both the Markov chains are developed. The approach is demonstrated by providing easier solutions to some slotted systems found in the literature. A few other apparently different modes of operation and corresponding models are shown to fall into the two model categories studied here. Key-Words: Discrete-time queues, slotted networks, performance analysis, Markov chains, crossbar switch, timing and synchronization.

Gaussian Mixture Parameter Estimation for Cognitive Radio and Network Surveillance Applications

Abstract: Cognitive radio is being heralded as an important, new frontier in radio communication; one that promises to overcome spectrum-congestion hotspots. In the cognitive radio approach, different groups of radio users may operate in the same spectrum region. The radio systems intelligently and dynamically change their transmission schemes during operation to co-exist. Therefore, a fundamental issue in cognitive radio is being able to assess and track users on a wireless channel. This problem occurs when the cognitive radio system is searching for friendly data or usable channels. The received and preprocessed signal typically turns out to be a Gaussian mixture random variable with common component variance. The task then is to quickly estimate and continue tracking the parameters of this mixture random variable from samples of data. Two efficient and easily-implemented methods for estimating all these parameters are developed, using a novel approach of fitting the cumulative distribution function (cdf) to the estimated cdf, and nonlinear, unconstrained optimization. The algorithms are demonstrated through simulation experiments. The algorithms presented here compare favourably with the general EM algorithm and are better suited for cognitive radio and wireless network surveillance applications