Reconstructing embedding spaces of coupled dynamical systems from multivariate data

A method for reconstructing dimensions of subspaces for weakly coupled dynamical systems is offered. The tool is able to extrapolate the subspace dimensions from the zero coupling limit, where the division of dimensions as per the algorithm is exact. Implementation of the proposed technique to multivariate data demonstrates its effectiveness in disentangling subspace dimensionalities also in the case of emergent synchronized motions, for both numerical and experimental systems.

Three coupled oscillators as a universal probe of synchronization stability in coupled oscillator arrays

We show that the stability surface that governs the synchronization of a large class of arrays of identical oscillators can be probed with a simple array of just three identical oscillators. Experimentally this implies that it may be possible to probe the synchronization conditions of many arrays all at the same time. In the process of developing a theory of the three-oscillator probe, we also show that several regimes of asymptotic coupling can be derived for the array classes, including the case of large imaginary coupling, which apparently has not been explored.

Meningiomas, dicentric chromosomes, gliomas, and telomerase activity

Lack of telomere maintenance during cell replication leads to telomere erosion and loss of function. This can result in telomere associations which probably cause the dicentric chromosomes seen in some tumour cells. One mechanism of telomere maintenance in dividing cells is the action of telomerase, a ribonucleoprotein enzyme that adds TTAGGG repeats onto telomeres and compensates for their shortening during cell division. Over 90 per cent of extracranial malignant neoplasms have been found to have telomerase activity. This study sought to determine if there was a relationship between absence of telomerase activity and presence of dicentric chromosomes in meningiomas and to what extent the other main group of central nervous system tumours, the gliomas, expressed telomerase activity. Telomerase activity was measured on 25 meningiomas and 29 gliomas. Four of the meningiomas were atypical variants and 11 were positive for dicentric chromosomes. Twenty-five of 29 gliomas were glioblastoma multiforme tumours. Measures were taken to ensure absence of false positives due to primer-dimer interaction and false negatives due to protein degradation or the presence of Taq polymerase inhibitors. All 25 meningiomas and the four low-grade gliomas (WHO grade II) were telomerase activity-negative. Seven (28 per cent) of the 25 glioblastoma multiforme tumours showed telomerase activity. The absence of telomerase activity in meningiomas and the high frequency of telomere associations support the hypothesis that these tumours are benign, transformed but pre-crisis. The relatively low frequency of telomerase activity in the malignant glioblastoma multiforme suggests that most of these tumours may have other mechanisms of telomere maintenance and that the potentially therapeutic telomerase inhibitors will not be of great value in the future management of the majority of patients suffering from these tumours.

Novel technetium-99m-labeled platelet GPIIb/IIIa receptor antagonists as potential imaging agents for venous and arterial thrombosis

OBJECTIVES

Either venous or arterial thrombosis is a potentially life-threatening event and existing diagnostic modalities are inadequate to diagnose and to determine the morphology of the evolving thrombus. Thus development of a noninvasive imaging agent that can detect clot location remains a critical and unmet need in nuclear diagnostic medicine. The present study was undertaken to determine the potential of platelet GPIIb/IIIa receptors compared with direct thrombin inhibitors, in the detection of venous and arterial clots.

METHODS

Initially, the validity of exploiting the degree and extent of specific uptake and retention of a potent GPIIb/IIIa receptor antagonist in venous and in arterial thrombus was confirmed in vitro in artificially created arterial- or venous-type clots, using the radiolabeled antagonist, 3H-DMP728. This was followed by comparing the in-vivo clot/blood distribution of various technetium-99m (99mTc)-labeled, DMP728-derived, GPIIb/IIIa receptor antagonists and of thrombin inhibitors, over time, in mixed arterial/venous or venous clots in arteriovenous shunt and in venous clot models in dogs. In addition, we performed noninvasive single-photon emission tomographic imaging of the venous clot in a deep vein thrombosis model in dogs.

RESULTS

Our data confirmed that potency for the platelet GPIIb/IIIa receptors was maintained after radiolabeling of the parent active GPIIb/IIIa receptor antagonists. DMP728 demonstrated a relatively greater affinity for activated than for unactivated human platelets, which might be essential for attaining an optimal thrombus/blood (target/background) distribution ratio and the optimal detection of small clots (i.e. greater sensitivity).

CONCLUSIONS

These data suggest a potential utility of 99mTc-GPIIb/IIIa receptor antagonists, but not of direct thrombin inhibitors, in the diagnosis of venous clots in deep vein thrombosis, pulmonary embolism and arterial thromboembolic disorders including stroke and coronary and peripheral artery thrombotic disorders.

Subarachnoid hemorrhage due to late recurrence of a previously unruptured aneurysm after complete endovascular occlusion

We present a case of subarachnoid hemorrhage attributed to rupture of an aneurysm 18 months after endovascular occlusion. The aneurysm was diagnosed after the patient had a seizure; however, there was no evidence of subarachnoid hemorrhage. Angiography at 6 months revealed a totally occluded aneurysm. This case illustrates that the long-term results of endovascular occlusion remain uncertain.

A strategy for empowerment: the role of midwives in computer systems implementation

The procurement and implementation of patient administration systems has been done on numerous occasions in the past. The Rotunda project however encompassed major bespoke clinical developments which were going to impact upon large clusters of midwives, and medical staff to a lesser extent. A broad based four level structured methodology was used to implement the project which is significantly ahead of schedule. This methodology together with its strengths and weaknesses is comprehensively discussed. The empowerment of midwives, their roles in systems analysis and design, software testing and organisational re-engineering is described. The importance of undertaking comprehensive computer training is highlighted and a compact 10 h information technology course coupled with ongoing educational and related activities which could be adopted by any organisation is documented. The seven deadly sins of project management are mapped out. An update on benefits realisation is provided. Gender issues are also discussed.

Partners in powersharing--the role of midwives in information technology

The contribution which midwives can make to the successful implementation of information systems is described. Issues such as Change Management, Quality, Benefits Realisation, and Public Relations are discussed. Damage limitation in the information age is outlined.

Investment appraisal of the protection, confidentiality and security arrangements of patient data

Data Protection and Security issues are reviewed in relevant literature. Policies implemented in relation to the subject matter are discussed in detail. Findings from a review of data protection and security arrangements at a major hospital are presented. Future data protection and security recommendations are outlined.

The Dandy-Walker syndrome--a 10-year experience of its management and outcome

Hydroephalus of childhood may be associated with intracranial haemorrhage, infection, aqueductal stenosis, Arnold-Chiari malformation (spina bifida), tumours or more uncommonly with the Dandy-Walker syndrome (DWS). We present our experience with the management of this condition over a 10-year period. Twelve children with a definite diagnosis of DWS are reviewed with regard to the age at diagnosis, investigations, treatment, associated problems and overall outcome. Two patients died; there was a high incidence of mental retardation (65%) and associated problems. All but one child had ventriculo-peritoneal shunting and two had cysto-peritoneal shunts in addition to their V-P shunts. There were no familial cases; one child had a chromosomal abnormality. Although the long-term outcome is dismal in most cases, about 35% of the children have a reasonable outcome and hence the condition warrants energetic treatment.

A comparison of conventional and matched filtering techniques for rapid eye movement detection of the newborn

This paper compares an extended conventional filter technique for automated detection and analysis of rapid eye movements (REM) in neonates, using amplitude, synchrony, velocity, and coherence threshold criteria, with a matched filtering technique using the morphology of the REM waveform. Analyses of both simulated and real data were carried out. Automated REM tabulations are compared with visual scoring by a trained observer. Both preterm and fullterm neonates were used to test these methods. Both the advantages and disadvantages of these two techniques are discussed as compared with conventional methods which use only amplitude and synchrony threshold criteria. The major advantage of the extended conventional over the conventional method, as well as the matched filtering over the extended conventional technique, is the increased REM detection rate for ten minute intervals of artifact-free sleep. More accurate methods of automated REM detection that can be applied over extended monitoring periods are still needed.