Spatio-temporal Organization During Ventricular Fibrillation in the Human Heart

In this paper, we present a novel approach to quantify the spatio-temporal organization of electrical activation during human ventricular fibrillation (VF). We propose three different methods based on correlation analysis, graph theoretical measures and hierarchical clustering. Using the proposed approach, we quantified the level of spatio-temporal organization during three episodes of VF in ten patients, recorded using multi-electrode epicardial recordings with 30 s coronary perfusion, 150 s global myocardial ischaemia and 30 s reflow. Our findings show a steady decline in spatio-temporal organization from the onset of VF with coronary perfusion. We observed transient increases in spatio-temporal organization during global myocardial ischaemia. However, the decline in spatio-temporal organization continued during reflow. Our results were consistent across all patients, and were consistent with the numbers of phase singularities. Our findings show that the complex spatio-temporal patterns can be studied using complex network analysis

Learning Behavior of Memristor-Based Neuromorphic Circuits in the Presence of Radiation

In this paper, a feed-forward spiking neural network with memristive synapses is designed to learn a spatio-temporal pattern representing the 25-pixel character ‘B’ by separating correlated and uncorrelated afferents. The network uses spike-timing-dependent plasticity (STDP) learning behavior, which is implemented using biphasic neuron spikes. A TiO2 memristor non-linear drift model is used to simulate synaptic behavior in the neuromorphic circuit. The network uses a many-to-one topology with 25 pre-synaptic neurons (afferent) each connected to a memristive synapse and one post-synaptic neuron. The memristor model is modified to include the experimentally observed effect of state-altering radiation. During the learning process, irradiation of the memristors alters their conductance state, and the effect on circuit learning behavior is determined. Radiation is observed to generally increase the synaptic weight of the memristive devices, making the network connections more conductive and less stable. However, the network appears to relearn the pattern when radiation ceases but does take longer to resolve the correlation and pattern. Network recovery time is proportional to flux, intensity, and duration of the radiation. Further, at lower but continuous radiation exposure, (flux 1x1010 cm−2 s−1 and below), the circuit resolves the pattern successfully for up to 100 s

Intensive support for adults with intellectual disability and behaviours that challenge: a survey of provision and service typologies in England

BACKGROUND: Approximately 18% of adults with intellectual disabilities living in the community display behaviours that challenge. Intensive support teams (ISTs) have been recommended to provide high-quality responsive care aimed at avoiding unnecessary admissions and reducing lengthy in-patient stays. AIMS: To identify and describe the geographical distribution and characteristics of ISTs, and to develop a typology of IST service models in England. METHOD: We undertook a national cross-sectional survey of 73 ISTs. A hierarchical cluster analysis was performed based on six prespecified grouping factors (mode of referrals, size of case-load, use of outcome measures, staff composition, hours of operation and setting of service). A simplified form of thematic analysis was used to explore free-text responses. RESULTS: Cluster analysis identified two models of IST provision: (a) independent and (b) enhanced provision based around a community intellectual disability service. ISTs aspire to adopt person-centred care, mostly use the framework of positive behaviour support for behaviour that challenges, and report concerns about organisational and wider context issues. CONCLUSIONS: This is the first study to examine the delivery of intensive support to people with intellectual disability and behaviour that challenges. A two-cluster model of ISTs was found to have statistical validity and clinical utility. The clinical heterogeneity indicates that further evaluation of these service models is needed to establish their clinical and cost-effectiveness

Assessment for learning : a model for the development of a child’s self competence in the early years of education

In recent years policy documents, curricula and other educational initiatives have promoted a pedagogy founded on the concept of independent learning. This is broadly defined as ‘having the belief in yourself to think through learning activities, problems or challenges, make decisions about your learning and act upon those decisions (Blandford and Knowles, 2009:336). The central role of Assessment for Learning (AfL) in this process is often overlooked in practice. By considering the findings from a small scale research study this article addresses the central role of the teacher /practitioner in developing effective AfL in the early years classroom (3-5 years)

Rate of Decline of the Oriental White-Backed Vulture Population in India Estimated from a Survey of Diclofenac Residues in Carcasses of Ungulates

The non-steroidal anti-inflammatory drug diclofenac is a major cause of the rapid declines in the Indian subcontinent of three species of vultures endemic to South Asia. The drug causes kidney failure and death in vultures. Exposure probably arises through vultures feeding on carcasses of domesticated ungulates treated with the drug. However, before the study reported here, it had not been established from field surveys of ungulate carcasses that a sufficient proportion was contaminated to cause the observed declines. We surveyed diclofenac concentrations in samples of liver from carcasses of domesticated ungulates in India in 2004–2005. We estimated the concentration of diclofenac in tissues available to vultures, relative to that in liver, and the proportion of vultures killed after feeding on a carcass with a known level of contamination. We assessed the impact of this mortality on vulture population trend with a population model. We expected levels of diclofenac found in ungulate carcasses in 2004–2005 to cause oriental white-backed vulture population declines of 80–99% per year, depending upon the assumptions used in the model. This compares with an observed rate of decline, from road transect counts, of 48% per year in 2000–2003. The precision of the estimate based upon carcass surveys is low and the two types of estimate were not significantly different. Our analyses indicate that the level of diclofenac contamination found in carcasses of domesticated ungulates in 2004–2005 was sufficient to account for the observed rapid decline of the oriental white-backed vulture in India. The methods we describe could be used again to assess changes in the effect on vulture population trend of diclofenac and similar drugs. In this way, the effectiveness of the recent ban in India on the manufacture and importation of diclofenac for veterinary use could be monitored

Ethnopolitics Across Central and Eastern Europe in a State of Flux: Time for Updating and Upgrading?

This chapter illustrates why and how the existing theoretical models in the study of ethnopolitics need to be updated in light of the latest developments and the increasing impact of new catalysts. These are, namely, anti-immigration and the rise of the populist and radical right across Central and Eastern Europe. This chapter hints that the more systematic cooperation between academic experts in nationalism and academic experts in the populist and radical right will enable: (a) the former to assess more accurately the degree to which new variables such as Euroscepticism and anti-immigrant trends can reshape ethnopolitics, both as a living reality and a field of study, across Central and Eastern Europe; (b) the latter to formulate new interpretative models about how (right-wing) populist and Eurosceptic actors embed their agendas inside the pre-existing political cultures of nationalism and particularistic identity and memory politics. This chapter introduces and outlines the ethnosymbolic approach as well as the triadic and quadratic configurations of ethnopolitics. Then, it proceeds into a more empirical assessment of the applicability of these theoretical approaches in a series of case studies during the 1990s, as well as the more recent emergence of new catalysts and the ensuing necessity to update and upgrade the existing theoretical models

Comparative Evaluation of Methodologies for T-wave Alternans Mapping in Electrograms.

Electrograms (EGM) recorded from the surface of the myocardium are becoming more and more accessible. T-wave alternans (TWA) is associated with increased vulnerability to ventricular tachycardia/fibrillation and it occurs before the onset of ventricular arrhythmias. Thus, accurate methodologies for time-varying alternans estimation/detection in EGM are needed. In this paper, we perform a simulation study based on epicardial EGM recorded in vivo in humans to compare the accuracy of four methodologies: the spectral method (SM), modified moving average method (MMA), laplacian likelihood ratio method (LLR) and a novel method based on time-frequency distributions (TFD). A variety of effects are considered, which include the presence of wide band noise, respiration and impulse artifacts. We found that (a) EGM-TWA can be detected accurately when the standard deviation of wide band noise is equal or smaller than 10 times the magnitude of EGM-TWA. (b) Respiration can be critical for EGM-TWA analysis, even at typical respiratory rates. (c) Impulse noise strongly reduces the accuracy of all methods, except LLR. (d) If depolarization time is used as a fiducial point, the localization of the T-wave is not critical for the accuracy of EGMTWA detection. (e) According to this study, all methodologies provided accurate EGM-TWA detection/quantification in ideal conditions, while LLR was the most robust, providing better detection-rates in noisy conditions. Application on epicardial mapping of the in-vivo human heart shows that EGM-TWA has heterogeneous spatio-temporal distribution

ESC core curriculum for the general cardiologist (2013)

[No abstract available

Neutrophil Elastase Enhances Sputum Solubilization in Cystic Fibrosis Patients Receiving DNase Therapy

Cystic fibrosis patients suffer from chronic lung infection and inflammation due to the secretion of viscous sputum. Sputum viscosity is caused by extracellular DNA, some of which originates from the release of neutrophil extracellular traps (NETs). During NET formation neutrophil elastase (NE) partially processes histones to decondense chromatin. NE is abundant in CF sputum and is thought to contribute to tissue damage. Exogenous nucleases are a palliative treatment in CF as they promote sputum solubilization. We show that in a process reminiscent of NET formation, NE enhances sputum solubilization by cleaving histones to enhance the access of exogenous nucleases to DNA. In addition, we find that in Cf sputum NE is predominantly bound to DNA, which is known to downregulate its proteolytic activity and may restrict host tissue damage. The beneficial role of NE in CF sputum solubilization may have important implications for the development of CF therapies targeting NE

Metabolism of aceclofenac in cattle to vulture-killing diclofenac

The non-steroidal anti-inflammatory drug (NSAID) diclofenac is highly toxic to Gyps vultures and its recent widespread use in South Asia caused catastrophic declines in at least three scavenging raptors. The manufacture of veterinary formulations of diclofenac has since been banned across the region with mixed success. However, at least 12 other NSAIDs are available for veterinary use in South Asia. Aceclofenac is one of these compounds and it is known to metabolise into diclofenac in some mammal species. The metabolic pathway of aceclofenac in cattle, the primary food of vultures in South Asia, is unknown. In this study, we give six cattle the recommended dose of aceclofenac (2 mg/kg), collect blood along a time series and undertake a pharmacokinetic analysis of aceclofenac and diclofenac-metabolites in their plasma using liquid chromatography with mass spectrometry. We found that nearly all of the aceclofenac administered to the cattle was very rapidly metabolised into diclofenac. Therefore, treating livestock with pure diclofenac or aceclofenac poses the same risk to vultures. This fact, coupled with the risk that aceclofenac may replace diclofenac in the veterinary market, fortifies the need for an immediate ban on all aceclofenac formulations that can be used to treat livestock. Without such a ban, the recovery of vultures across South Asia will not be successful.This study was largely funded by the RSPB Centre for Conversation Science. In addition, SAC Consulting: Veterinary Services receives funding from the Scottish Government through the Veterinary and Advisory Services (VAS) programme.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1523-17392017-10-31hb2016Paraclinical Science