EMG signal decomposition: how can it be accomplished and used?

Electromyographic (EMG) signals are composed of the superposition of the activity of individual motor units. Techniques exist for the decomposition of an EMG signal into its constituent components. Following is a review and explanation of the techniques that have been used to decompose EMG signals. Before describing the decomposition techniques, the fundamental composition of EMG signals is explained and after, potential sources of information from and various uses of decomposed EMG signals are described.     

What proportion of congenital abnormalities can be prevented?

OBJECTIVE--To estimate the proportion of preventable congenital abnormalities in Hungary. DESIGN--Analysis of available Hungarian data-bases and of the effectiveness of primary, secondary, and tertiary preventive methods. SETTING--Databases of ad hoc epidemiological studies and of the Hungarian congenital abnormality registry. MAIN OUTCOME MEASURES--Prevalence at birth and prevalence after prevention in 73 congenital abnormality types or groups. RESULTS--Preventive methods are available for 51 (70%) of the 73 congenital abnormality types or groups evaluated. The birth prevalence of all congenital abnormalities could be reduced from 65 to 26 per 1000; thus 39 per 1000 (60%) are preventable. Without congenital dislocation of the hip, which is unusually common in Hungary, the preventable proportion of congenital abnormalities is 52%. CONCLUSION--Many congenital abnormalities can be prevented, but as they do not represent a single pathological category there is no single strategy for their prevention.     

Environmental auditing: what is it and how can it contribute to environmental education?

The concept of environmental auditing and its use by industry and commerce are explained. A questionnaire-based method is described which can be used to introduce students to the techniques of environmental auditing, as well as developing problem-solving and communication skills and possibly even resulting in positive benefit to the educational institution.     

Teleost polarization vision: how it might work and what it might be good for

In this review, we will discuss the recent literature on fish polarization vision and we will present a model on how the retina processes polarization signals. The model is based on a general retinal-processing scheme and will be compared with the available electrophysiological data on polarization processing in the retina. The results of this model will help illustrate the functional significance of polarization vision for both feeding behaviour and navigation. First, we examine the linkage between structure and function in polarization vision in general.     

Modeling perceptual learning: difficulties and how they can be overcome

We investigated the roles of feedback and attention in training a vernier discrimination task as an example of perceptual learning. Human learning even of simple stimuli, such as verniers, relies on more complex mechanisms than previously expected – ruling out simple neural network models. These findings are not just an empirical oddity but are evidence that present models fail to reflect some important characteristics of the learning process. We will list some of the problems of neural networks and develop a new model that solves them by incorporating top-down mechanisms. Contrary to neural networks, in our model learning is not driven by the set of stimuli only. Internal estimations of performance and knowledge about the task are also incorporated. Our model implies that under certain conditions the detectability of only some of the stimuli is enhanced while the overall improvement of performance is attributed to a change of decision criteria. An experiment confirms this prediction. Received: 23 May 1996 / Accepted in revised form: 16 October 1997     

ICOS costimulation requires IL-2 and can be prevented by CTLA-4 engagement

We investigated the relationship between ICOS, CD28, CTLA-4, and IL-2 to gain a better understanding of this family of costimulatory receptors in the immune response. Using magnetic beads coated with anti-CD3 and varying amounts of anti-ICOS and anti-CTLA-4 Abs, we show that CTLA-4 ligation blocks ICOS costimulation. In addition to inhibiting cellular proliferation, CTLA-4 engagement prevented ICOS-costimulated T cells from producing IL-4, IL-10, and IL-13. Both an indirect and direct mechanism of CTLA-4's actions were examined. First, CTLA-4 engagement on resting cells was found to indirectly block ICOS costimulation by interferring with the signals needed to induce ICOS cell surface expression. Second, on preactivated cells that had high levels of ICOS expression, CTLA-4 ligation blocked the ICOS-mediated induction of IL-4, IL-10, and IL-13, suggesting an interference with downstream signaling pathways. The addition of IL-2 not only overcame both mechanisms, but also greatly augmented the level of cellular activation suggesting synergy between ICOS and IL-2 signaling. This cooperation between ICOS and IL-2 signaling was explored further by showing that the minimum level of IL-2 produced by ICOS costimulation was required for T cell proliferation. Finally, exogenous IL-2 was required for sustained growth of ICOS-costimulated T cells. These results indicate that stringent control of ICOS costimulation is maintained initially by CTLA-4 engagement and later by a requirement for exogenous IL-2.