2,934 research outputs found
Fractals in the Nervous System: conceptual Implications for Theoretical Neuroscience
This essay is presented with two principal objectives in mind: first, to
document the prevalence of fractals at all levels of the nervous system, giving
credence to the notion of their functional relevance; and second, to draw
attention to the as yet still unresolved issues of the detailed relationships
among power law scaling, self-similarity, and self-organized criticality. As
regards criticality, I will document that it has become a pivotal reference
point in Neurodynamics. Furthermore, I will emphasize the not yet fully
appreciated significance of allometric control processes. For dynamic fractals,
I will assemble reasons for attributing to them the capacity to adapt task
execution to contextual changes across a range of scales. The final Section
consists of general reflections on the implications of the reviewed data, and
identifies what appear to be issues of fundamental importance for future
research in the rapidly evolving topic of this review
The Bionic Radiologist: avoiding blurry pictures and providing greater insights
Radiology images and reports have long been digitalized. However, the potential of the more than 3.6 billion radiology
examinations performed annually worldwide has largely gone unused in the effort to digitally transform health care. The Bionic
Radiologist is a concept that combines humanity and digitalization for better health care integration of radiology. At a practical
level, this concept will achieve critical goals: (1) testing decisions being made scientifically on the basis of disease probabilities and
patient preferences; (2) image analysis done consistently at any time and at any site; and (3) treatment suggestions that are closely
linked to imaging results and are seamlessly integrated with other information. The Bionic Radiologist will thus help avoiding missed
care opportunities, will provide continuous learning in the work process, and will also allow more time for radiologists’ primary
roles: interacting with patients and referring physicians. To achieve that potential, one has to cope with many implementation
barriers at both the individual and institutional levels. These include: reluctance to delegate decision making, a possible decrease in
image interpretation knowledge and the perception that patient safety and trust are at stake. To facilitate implementation of the
Bionic Radiologist the following will be helpful: uncertainty quantifications for suggestions, shared decision making, changes in
organizational culture and leadership style, maintained expertise through continuous learning systems for training, and role
development of the involved experts. With the support of the Bionic Radiologist, disparities are reduced and the delivery of care is
provided in a humane and personalized fashion
Networks of Recurrent Events, a Theory of Records, and an Application to Finding Causal Signatures in Seismicity
We propose a method to search for signs of causal structure in spatiotemporal
data making minimal a priori assumptions about the underlying dynamics. To this
end, we generalize the elementary concept of recurrence for a point process in
time to recurrent events in space and time. An event is defined to be a
recurrence of any previous event if it is closer to it in space than all the
intervening events. As such, each sequence of recurrences for a given event is
a record breaking process. This definition provides a strictly data driven
technique to search for structure. Defining events to be nodes, and linking
each event to its recurrences, generates a network of recurrent events.
Significant deviations in properties of that network compared to networks
arising from random processes allows one to infer attributes of the causal
dynamics that generate observable correlations in the patterns. We derive
analytically a number of properties for the network of recurrent events
composed by a random process. We extend the theory of records to treat not only
the variable where records happen, but also time as continuous. In this way, we
construct a fully symmetric theory of records leading to a number of new
results. Those analytic results are compared to the properties of a network
synthesized from earthquakes in Southern California. Significant disparities
from the ensemble of acausal networks that can be plausibly attributed to the
causal structure of seismicity are: (1) Invariance of network statistics with
the time span of the events considered, (2) Appearance of a fundamental length
scale for recurrences, independent of the time span of the catalog, which is
consistent with observations of the ``rupture length'', (3) Hierarchy in the
distances and times of subsequent recurrences.Comment: 19 pages, 13 figure
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