57 research outputs found
Channel-Independent and Sensor-Independent Stimulus Representations
This paper shows how a machine, which observes stimuli through an
uncharacterized, uncalibrated channel and sensor, can glean machine-independent
information (i.e., channel- and sensor-independent information) about the
stimuli. First, we demonstrate that a machine defines a specific coordinate
system on the stimulus state space, with the nature of that coordinate system
depending on the device's channel and sensor. Thus, machines with different
channels and sensors "see" the same stimulus trajectory through state space,
but in different machine-specific coordinate systems. For a large variety of
physical stimuli, statistical properties of that trajectory endow the stimulus
configuration space with differential geometric structure (a metric and
parallel transfer procedure), which can then be used to represent relative
stimulus configurations in a coordinate-system-independent manner (and,
therefore, in a channel- and sensor-independent manner). The resulting
description is an "inner" property of the stimulus time series in the sense
that it does not depend on extrinsic factors like the observer's choice of a
coordinate system in which the stimulus is viewed (i.e., the observer's choice
of channel and sensor). This methodology is illustrated with analytic examples
and with a numerically simulated experiment. In an intelligent sensory device,
this kind of representation "engine" could function as a "front-end" that
passes channel/sensor-independent stimulus representations to a pattern
recognition module. After a pattern recognizer has been trained in one of these
devices, it could be used without change in other devices having different
channels and sensors.Comment: The results of a numerically simulated experiment, which illustrates
the proposed method, have been added to the version submitted on October 27,
2004. This paper has been accepted for publication in the Journal of Applied
Physics. For related papers, see http://www.geocities.com/dlevin2001
Hospital physicians perform five types of work duties in Japan: An observational study
Rubber Hands Feel Touch, but Not in Blind Individuals
Psychology and neuroscience have a long-standing tradition of studying blind individuals to investigate how visual experience shapes perception of the external world. Here, we study how blind people experience their own body by exposing them to a multisensory body illusion: the somatic rubber hand illusion. In this illusion, healthy blindfolded participants experience that they are touching their own right hand with their left index finger, when in fact they are touching a rubber hand with their left index finger while the experimenter touches their right hand in a synchronized manner (Ehrsson et al. 2005). We compared the strength of this illusion in a group of blind individuals (n = 10), all of whom had experienced severe visual impairment or complete blindness from birth, and a group of age-matched blindfolded sighted participants (n = 12). The illusion was quantified subjectively using questionnaires and behaviorally by asking participants to point to the felt location of the right hand. The results showed that the sighted participants experienced a strong illusion, whereas the blind participants experienced no illusion at all, a difference that was evident in both tests employed. A further experiment testing the participants' basic ability to localize the right hand in space without vision (proprioception) revealed no difference between the two groups. Taken together, these results suggest that blind individuals with impaired visual development have a more veridical percept of self-touch and a less flexible and dynamic representation of their own body in space compared to sighted individuals. We speculate that the multisensory brain systems that re-map somatosensory signals onto external reference frames are less developed in blind individuals and therefore do not allow efficient fusion of tactile and proprioceptive signals from the two upper limbs into a single illusory experience of self-touch as in sighted individuals
Spatial Language Processing in the Blind: Evidence for a Supramodal Representation and Cortical Reorganization
Neuropsychological and imaging studies have shown that the left supramarginal gyrus (SMG) is specifically involved in processing spatial terms (e.g. above, left of), which locate places and objects in the world. The current fMRI study focused on the nature and specificity of representing spatial language in the left SMG by combining behavioral and neuronal activation data in blind and sighted individuals. Data from the blind provide an elegant way to test the supramodal representation hypothesis, i.e. abstract codes representing spatial relations yielding no activation differences between blind and sighted. Indeed, the left SMG was activated during spatial language processing in both blind and sighted individuals implying a supramodal representation of spatial and other dimensional relations which does not require visual experience to develop. However, in the absence of vision functional reorganization of the visual cortex is known to take place. An important consideration with respect to our finding is the amount of functional reorganization during language processing in our blind participants. Therefore, the participants also performed a verb generation task. We observed that only in the blind occipital areas were activated during covert language generation. Additionally, in the first task there was functional reorganization observed for processing language with a high linguistic load. As the visual cortex was not specifically active for spatial contents in the first task, and no reorganization was observed in the SMG, the latter finding further supports the notion that the left SMG is the main node for a supramodal representation of verbal spatial relations
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
Soft law implementation in the EU multilevel system: legitimacy and governance efficiency revisited
Soft law instruments such as recommendations, guidelines or communications do not entail jurisdictional control, but produce important legal and practical effects. The literature on soft law frequently praises these instruments for enhancing governance efficiency through flexible problem solving. On the other hand critiques stress a lack of legitimacy as soft law is typically adopted outside the legislative arena. Yet, relatively little is known about concrete effects it takes at the national level. On the basis of case study evidence from Germany, this chapter shows that despite being non-binding, EU soft law is frequently implemented. Comparing implementation of nine soft law instruments in financial market regulation, social and environmental policy the chapter highlights that actors implement soft EU instruments either in the form of soft or hard law. Efficiency gains are frequently a main driver of implementation, while legitimacy and accountability become a concern where responsibilities are blurred during implementation
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