Determinants of the outcome of electrophysiologic study in patients with ventricular tachyarrhythmias

To determine those factors predictive of the ability to both initiate and suppress ventricular tachyarrhythmias during electrophysiologic study, the results of programmed cardiac stimulation were evaluated in 261 patients: 66 presenting with nonsustained ventricular tachycardia, 91 with sustained ventricular tachycardia and 104 with ventricular fibrillation. Multivariate logistic regression analysis revealed that the presenting arrhythmia was a potent and independent predictor of the ability to provoke ventricular arrhythmias at electrophysiologic study; a history of myocardial infarction and male sex were also significant independent predictors. Of patients presenting with sustained ventricular tachycardia, 89% (81 of 91) had inducible ventricular arrhythmias compared with 61 (40 of 66) and 66% (69 of 104) of patients with nonsustained ventricular tachycardia and ventricular fibrillation, respectively.Complete suppression of inducible arrhythmias could be achieved in only 52% (34 of 66) of patients with sustained ventricular tachycardia, compared with 73 (24 of 33) and 75% (46 of 61) of patients presenting with nonsustained ventricular tachycardia and ventricular fibrillation, respectively. Multivariate analysis showed that the major independent determinants of the ability to suppress inducible arrhythmias were the number of drug trials performed before electrophysiologic study (inversely correlated) and the nature of the induced arrhythmia.The nature of the presenting clinical arrhythmia is, therefore, a highly significant and independent predictor of the ability to induce ventricular arrhythmias during electrophysiologic testing and an important determinant of the ability to suppress induced arrhythmias in patients with spontaneous ventricular tachyarrhythmias

Translations: effects of viewpoint, feature, naming and context on identifying repeatedly copied drawings

We explored the tension between bottom – up and top – down contributions to object recognition in a collaboration between a visual artist and a cognitive psychologist. Initial pictorial renderings of objects and animals from various viewpoints were iteratively copied, and a series of drawings that changed from highly concrete images into highly abstract images was produced. In drawing identification in which sets were shown in reverse order, participants were more accurate, more confident, and quicker to correctly identify the evolving image when it was originally displayed from a canonical viewpoint with all salient features present. In drawing identification in which images were shown in random order, more abstract images could be resolved as a result of previously identifying a more concrete iteration of the same drawing. The results raise issues about the influence of viewpoint and feature on the preservation of pictorial images and about the role of labelling in the interpretation of ambiguous stimuli. In addition, the study highlights a procedure in which visual stimuli can degrade without necessitating a substantial loss of complexity

Random matrix theory for portfolio optimization: a stability approach

We apply Random Matrix Theory (RMT) on an empirically-measured financial correlation matrix, C, and show that this matrix contains a large amount of noise. In order to determine the sensitivity of the spectral properties of a random matrix to noise, we simulate a set of data and add different volumes of random noise. Having ascertained that the eigenspectrum is independent of the standard deviation of added noise, we use RMT to determine the noise percentage in a correlation matrix based on real data from S&P500. Eigenvalue and eigenvector analyses are applied and the experimental results for each of them are presented to identify qualitatively and quantitatively different spectral properties of the empirical correlation matrix to a random counterpart. Finally we attempt to separate the noisy part from the non-noisy part of C. We apply an existing technique to cleaning C and then discuss its associated problems. We propose a technique of filtering C which has many advantages, from a stability point of view over the existing method of cleaning

EpiGeNet : A graph database of interdependencies between genetic and epigenetic events in colorectal cancer

The development of colorectal cancer (CRC)—the third most common cancer type—has been associated with deregulations of cellular mechanisms stimulated by both genetic and epigenetic events. StatEpigen is a manually curated and annotated database, containing information on interdependencies between genetic and epigenetic signals, and specialized currently for CRC research. Although StatEpigen provides a well-developed graphical user interface for information retrieval, advanced queries involving associations between multiple concepts can benefit from more detailed graph representation of the integrated data. This can be achieved by using a graph database (NoSQL) approach. Data were extracted from StatEpigen and imported to our newly developed EpiGeNet, a graph database for storage and querying of conditional relationships between molecular (genetic and epigenetic) events observed at different stages of colorectal oncogenesis. We illustrate the enhanced capability of EpiGeNet for exploration of different queries related to colorectal tumor progression; specifically, we demonstrate the query process for (i) stage-specific molecular events, (ii) most frequently observed genetic and epigenetic interdependencies in colon adenoma, and (iii) paths connecting key genes reported in CRC and associated events. The EpiGeNet framework offers improved capability for management and visualization of data on molecular events specific to CRC initiation and progression

Fanny Copeland and the geographical imagination

Raised in Scotland, married and divorced in the English south, an adopted Slovene, Fanny Copeland (1872 – 1970) occupied the intersection of a number of complex spatial and temporal conjunctures. A Slavophile, she played a part in the formation of what subsequently became the Kingdom of Yugoslavia that emerged from the First World War. Living in Ljubljana, she facilitated the first ‘foreign visit’ (in 1932) of the newly formed Le Play Society (a precursor of the Institute of British Geographers) and guided its studies of Solčava (a then ‘remote’ Alpine valley system) which, led by Dudley Stamp and commended by Halford Mackinder, were subsequently hailed as a model for regional studies elsewhere. Arrested by the Gestapo and interned in Italy during the Second World War, she eventually returned to a socialist Yugoslavia, a celebrated figure. An accomplished musician, linguist, and mountaineer, she became an authority on (and populist for) the Julian Alps and was instrumental in the establishment of the Triglav National Park. Copeland’s role as participant observer (and protagonist) enriches our understanding of the particularities of her time and place and illuminates some inter-war relationships within G/geography, inside and outside the academy, suggesting their relative autonomy in the production of geographical knowledge