366 research outputs found
mLearning, development and delivery : creating opportunity and enterprise within the HE in FE context
This research project was funded by ESCalate in 2006-7 to support Somerset College in developing the curriculum, as well as widening participation via the use of mobile communications technologies such as mp3 players and mobile phones. The Project represents a highly topical and timely engagement with the opportunities for learning provided by the burgeoning use of mobile computing/ communications devices. Activities bring together colleagues from Teacher Education and Multimedia Computing in an innovative approach to designing for and delivering the curriculum. The Project addresses pedagogic issues and also vitally involves current and future learners, providing them with a new context for skills development and entrepreneurship. Anticipated outcomes include informed development of new HE modules and professional CPD activities which address the skills and context of this emerging approach to delivering the curriculum. The Project also intends to trial and evaluate the use of mobile technologies to support a blended learning approach to programme delivery and the development of a FD module which could be delivered via a mobile computing device. An interim report and a final project report are available as Word and PDF file
A combinatorial analog of the Poincaré Index Theorem
AbstractThe local configurations of arrows in directed graphs mapped on surfaces are related to one another by a relationship analogous to the Poincaré Index Theorem
Entrainment and chaos in a pulse-driven Hodgkin-Huxley oscillator
The Hodgkin-Huxley model describes action potential generation in certain
types of neurons and is a standard model for conductance-based, excitable
cells. Following the early work of Winfree and Best, this paper explores the
response of a spontaneously spiking Hodgkin-Huxley neuron model to a periodic
pulsatile drive. The response as a function of drive period and amplitude is
systematically characterized. A wide range of qualitatively distinct responses
are found, including entrainment to the input pulse train and persistent chaos.
These observations are consistent with a theory of kicked oscillators developed
by Qiudong Wang and Lai-Sang Young. In addition to general features predicted
by Wang-Young theory, it is found that most combinations of drive period and
amplitude lead to entrainment instead of chaos. This preference for entrainment
over chaos is explained by the structure of the Hodgkin-Huxley phase resetting
curve.Comment: Minor revisions; modified Fig. 3; added reference
New Methods for the Analysis of Heartbeat Behavior in Risk Stratification
Developing better methods for risk stratification for tachyarrhythmic sudden cardiac remains a major challenge for physicians and scientists. Since the transition from sinus rhythm to ventricular tachycardia/fibrillation happens by different mechanisms in different people, it is unrealistic to think that a single measure will be adequate to provide a good index for risk stratification. We analyze the dynamical properties of ventricular premature complexes over 24 h in an effort to understand the underlying mechanisms of ventricular arrhythmias and to better understand the arrhythmias that occur in individual patients. Two dimensional density plots, called heartprints, correlate characteristic features of the dynamics of premature ventricular complexes and the sinus rate. Heartprints show distinctive characteristics in individual patients. Based on a better understanding of the natures of transitions from sinus rhythm to sudden cardiac and the mechanisms of arrhythmia prior to cardiac arrest, it should be possible to develop better methods for risk stratification
Complex Motor Dynamics and Control in Multi-looped Negative Feedback Systems
Experiments were performed in normal and Parkinsonian subjects who were asked to maintain a constant finger position using time-delayed visual feedback. The finger position showed complex dynamics, with characteristic differences between normal and Parkinosonian subjects. Here we discuss some of the theoretical issues that must be resolved in order to understand the mechanisms that underlie the generation of these complex signals
Time-Dependent Solution for a Star Immersed in a Background Radiation
We study a time-dependent and spherically-symmetric solution with a star-like
source. We show that this solution can be interpreted as an exterior solution
of a contracting star which has a decreasing temperature and is immersed in a
homogenous and isotropic background radiation. Distribution of the temperature
in the fields and close-to Schwarzschild approximation of the solution are
studied. By identifying the radiation with the cosmic background one, we find
that the close-to-Schwarzschild approximate solution is valid in a wide range
in our solar system. Possible experimental tests of the solution are discussed
briefly.Comment: Latex, 7 pages, no figures, to appear in J. Math. Phys.(2002
Dynamical Disease: Identification, Temporal Aspects and Treatment Strategies for Human Illness
Dynamical diseases are characterized by sudden changes in the qualitative dynamics of physiological processes, leading to abnormal dynamics and disease. Thus, there is a natural matching between the mathematical field of nonlinear dynamics and medicine. This paper summarizes advances in the study of dynamical disease with emphasis on a NATO Advanced Research Workshop held in Mont Tremblant, Quebec, Canada in February 1994. We describe the international effort currently underway to identify dynamical diseases and to study these diseases from a perspective of nonlinear dynamics. Linear and nonlinear time series analysis combined with analysis of bifurcations in dynamics are being used to help understand mechanisms of pathological rhythms and offer the promise for better diagnostic and therapeutic techniques
Reverse Engineering the Gap Gene Network of Drosophila melanogaster
A fundamental problem in functional genomics is to determine the structure and dynamics of genetic networks based on expression data. We describe a new strategy for solving this problem and apply it to recently published data on early Drosophila melanogaster development. Our method is orders of magnitude faster than current fitting methods and allows us to fit different types of rules for expressing regulatory relationships. Specifically, we use our approach to fit models using a smooth nonlinear formalism for modeling gene regulation (gene circuits) as well as models using logical rules based on activation and repression thresholds for transcription factors. Our technique also allows us to infer regulatory relationships de novo or to test network structures suggested by the literature. We fit a series of models to test several outstanding questions about gap gene regulation, including regulation of and by hunchback and the role of autoactivation. Based on our modeling results and validation against the experimental literature, we propose a revised network structure for the gap gene system. Interestingly, some relationships in standard textbook models of gap gene regulation appear to be unnecessary for or even inconsistent with the details of gap gene expression during wild-type development
Sufficient Conditions for Fast Switching Synchronization in Time Varying Network Topologies
In previous work, empirical evidence indicated that a time-varying network
could propagate sufficient information to allow synchronization of the
sometimes coupled oscillators, despite an instantaneously disconnected
topology. We prove here that if the network of oscillators synchronizes for the
static time-average of the topology, then the network will synchronize with the
time-varying topology if the time-average is achieved sufficiently fast. Fast
switching, fast on the time-scale of the coupled oscillators, overcomes the
descychnronizing decoherence suggested by disconnected instantaneous networks.
This result agrees in spirit with that of where empirical evidence suggested
that a moving averaged graph Laplacian could be used in the master-stability
function analysis. A new fast switching stability criterion here-in gives
sufficiency of a fast-switching network leading to synchronization. Although
this sufficient condition appears to be very conservative, it provides new
insights about the requirements for synchronization when the network topology
is time-varying. In particular, it can be shown that networks of oscillators
can synchronize even if at every point in time the frozen-time network topology
is insufficiently connected to achieve synchronization.Comment: Submitted to SIAD
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