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1.
James Justus 《Biology & philosophy》2006,21(5):647-666
Richard Levins has advocated the scientific merits of qualitative modeling throughout his career. He believed an excessive
and uncritical focus on emulating the models used by physicists and maximizing quantitative precision was hindering biological
theorizing in particular. Greater emphasis on qualitative properties of modeled systems would help counteract this tendency,
and Levins subsequently developed one method of qualitative modeling, loop analysis, to study a wide variety of biological
phenomena. Qualitative modeling has been criticized for being conceptually and methodologically problematic. As a clear example
of a qualitative modeling method, loop analysis shows this criticism is indefensible. The method has, however, some serious
limitations. This paper describes loop analysis, its limitations, and attempts to clarify the differences between quantitative
and qualitative modeling, in content and objective. Loop analysis is but one of numerous types of qualitative analysis, so
its limitations do not detract from the currently underappreciated and underdeveloped role qualitative modeling could have
within science.
相似文献
James JustusEmail: |
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Francois B. Vialatte Justin Dauwels Monique Maurice Yoko Yamaguchi Andrzej Cichocki 《Cognitive neurodynamics》2009,3(3):251-261
In this paper, we investigate the large-scale synchrony of EEG oscillatory bursts, during stimulation by a flickering square
of light. Whereas most studies focus on averaged raw EEG responses, this study considers oscillatory events within EEG of single trials, which leads to various new insights. We recorded EEG signals before, during and after stimulation by a flickering
square of light in medium (16 Hz) and high frequency (32 Hz) ranges. Similar oscillatory bursts, to those observed in spontaneous
EEG, can be found in single-trial synchrony of steady state visual evoked potentials (SSVEP). These bursts are extracted from
the EEG of single trials using bump modeling. Stochastic event synchrony method is applied to those events, which quantifies
synchronies of oscillatory bursts on a large-scale basis. Those oscillatory patterns have a significantly higher degree of
co-occurrence during SSVEP, uncorrelated with ongoing signal synchrony. It means that EEG oscillatory patterns are presumably
an outcome of brain activity, rather than a mere side effect of ongoing EEG. They undergo a consistent reorganization during
visual stimulation, preferentially along the visual pathway, depending on magno or parvo stimulations. Flickering stimuli
may induce some cognitive side-effects depending on the stimulation frequency.
相似文献
Francois B. VialatteEmail: |
5.
Sub-Antarctic Marion Island has had a permanent research station for 50 years and the islands Wandering Albatrosses have been intensively studied for 20 years. The reactions of breeding birds to approaches by a human on foot were recorded. Three response variables were calculated: intensity of vocal reaction (IVR), intensity of non-vocal reaction (INR) and overall response index (ORI). At 5 m from the nest, twice as many birds stood and/or vocalised as at 15 m. Nearest neighbour distance, age and gender did not explain individual variability of responses. Study colony birds had higher IVR scores than non-study colony birds; birds at colonies closest to the station had the highest ORI scores. A better breeding record was associated with lower IVR and ORI scores, but a causative relationship remains to be demonstrated. A minimum viewing distance of 25 m is recommended for breeding Wandering Albatrosses.
相似文献
Marienne S. de VilliersEmail: Fax: +27-21-6503434 |
John CooperEmail: |
Peter G. RyanEmail: |
6.
Event-related brain potentials (ERP) are important neural correlates of cognitive processes. In the domain of language processing,
the N400 and P600 reflect lexical-semantic integration and syntactic processing problems, respectively. We suggest an interpretation
of these markers in terms of dynamical system theory and present two nonlinear dynamical models for syntactic computations
where different processing strategies correspond to functionally different regions in the system’s phase space.
相似文献
Peter beim GrabenEmail: |
7.
A key point in the analysis of dynamical models of biological systems is to handle systems of relatively high dimensions.
In the present paper we propose a method to hierarchically organize a certain type of piecewise affine (PWA) differential
systems. This specific class of systems has been extensively studied for the past few years, as it provides a good framework
to model gene regulatory networks. The method, shown on several examples, allows a qualitative analysis of the asymptotic
behavior of a PWA system, decomposing it into several smaller subsystems. This technique, based on the well-known strongly
connected components decomposition, is not new. However, its adaptation to the non-smooth PWA differential equations turns
out to be quite relevant because of the strong discrete structure underlying these equations. Its biological relevance is
shown on a 7-dimensional PWA system modeling the gene network responsible for the carbon starvation response in Escherichia coli.
相似文献
Laurent Tournier (Corresponding author)Email: |
Jean-Luc GouzéEmail: |
8.
Andrei V. Sazonov Chin Keong Ho Jan W. M. Bergmans Johan B. A. M. Arends Paul A. M. Griep Evgeny A. Verbitskiy Pierre J. M. Cluitmans Paul A. J. M. Boon 《Biological cybernetics》2009,100(2):129-146
The phase locking index (PLI) was introduced to quantify in a statistical sense the phase synchronization of two signals.
It has been commonly used to process biosignals. In this article, we investigate the PLI for measuring the interdependency
of cortical source signals (CSSs) recorded in the Electroencephalogram (EEG). To this end, we consider simple analytical models
for the mapping of simulated CSSs into the EEG. For these models, the PLI is investigated analytically and through numerical
simulations. An evaluation is made of the sensitivity of the PLI to the amount of crosstalk between the sources through biological
tissues of the head. It is found that the PLI is a useful interdependency measure for CSSs, especially when the amount of
crosstalk is small. Another common interdependency measure is the coherence. A direct comparison of both measures has not been made in the literature so far. We assess the performance of the PLI and
coherence for estimation and detection purposes based on, respectively, a normalized variance and a novel statistical measure termed contrast. Based on these performance measures, it is found that the PLI is similar or better than the CM in most cases. This result
is also confirmed through analysis of EEGs recorded from epileptic patients.
相似文献
Andrei V. SazonovEmail: |
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In this study, based on the view of statistical inference, we investigate the robustness of neural codes, i.e., the sensitivity
of neural responses to noise, and its implication on the construction of neural coding. We first identify the key factors
that influence the sensitivity of neural responses, and find that the overlap between neural receptive fields plays a critical
role. We then construct a robust coding scheme, which enforces the neural responses not only to encode external inputs well,
but also to have small variability. Based on this scheme, we find that the optimal basis functions for encoding natural images
resemble the receptive fields of simple cells in the striate cortex. We also apply this scheme to identify the important features
in the representation of face images and Chinese characters.
相似文献
Sheng LiEmail: |
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Andres Quiroz Nathan Gnanasambandam Manish Parashar Naveen Sharma 《Cluster computing》2009,12(1):73-85
We present a decentralized algorithm for online clustering analysis used for anomaly detection in self-monitoring distributed
systems. In particular, we demonstrate the monitoring of a network of printing devices that can perform the analysis without
the use of external computing resources (i.e. in-network analysis). We also show how to ensure the robustness of the algorithm,
in terms of anomaly detection accuracy, in the face of failures of the network infrastructure on which the algorithm runs.
Further, we evaluate the tradeoff in terms of overhead necessary for ensuring this robustness and present a method to reduce
this overhead while maintaining the detection accuracy of the algorithm.
相似文献
Naveen SharmaEmail: |
12.
The recent contribution by Jarmila Kukalová-Peck on Hennigian phylogenetics and hexapod limb evolution is critically evaluated.
相似文献
Michael S. Engel (Corresponding author)Email: |
13.
Peter Olofsson 《Biology & philosophy》2008,23(4):545-553
The explanatory filter is a proposed method to detect design in nature with the aim of refuting Darwinian evolution. The explanatory filter borrows
its logical structure from the theory of statistical hypothesis testing but we argue that, when viewed within this context,
the filter runs into serious trouble in any interesting biological application. Although the explanatory filter has been extensively
criticized from many angles, we present the first rigorous criticism based on the theory of mathematical statistics.
相似文献
Peter OlofssonEmail: |
14.
We present two computational models (i) long-range horizontal connections and the nonlinear effect in V1 and (ii) the filling-in
process at the blind spot. Both models are obtained deductively from standard regularization theory to show that physiological
evidence of V1 and V2 neural properties is essential for efficient image processing. We stress that the engineering approach
should be imported to understand visual systems computationally, even though this approach usually ignores physiological evidence
and the target is neither neurons nor the brain.
相似文献
Shunji SatohEmail: |
15.
Peter beim Graben Dimitris Pinotsis Douglas Saddy Roland Potthast 《Cognitive neurodynamics》2008,2(2):79-88
We construct a mapping from complex recursive linguistic data structures to spherical wave functions using Smolensky’s filler/role
bindings and tensor product representations. Syntactic language processing is then described by the transient evolution of
these spherical patterns whose amplitudes are governed by nonlinear order parameter equations. Implications of the model in
terms of brain wave dynamics are indicated.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.
相似文献
Peter beim GrabenEmail: |
16.
Terry Harmer 《Cluster computing》2007,10(3):277-285
Gridcast is an R&D project investigating grid ideas and technologies in the broadcasting technical infrastructure. In this
paper I discuss the business and technical issues in building infrastructures to support broadcasters and outline the structure
of the Gridcast grid-based service oriented architecture for broadcasting playout support.
相似文献
Terry HarmerEmail: |
17.
Peter Godfrey-Smith 《Biology & philosophy》2007,22(3):429-437
Jablonka and Lamb's claim that evolutionary biology is undergoing a ‘revolution’ is queried. But the very concept of revolutionary
change has uncertain application to a field organized in the manner of contemporary biology. The explanatory primacy of sequence
properties is also discussed.
相似文献
Peter Godfrey-SmithEmail: |
18.
Debates over adaptationism can be clarified and partially resolved by careful consideration of the ‘grain’ at which evolutionary
processes are described. The framework of ‘adaptive landscapes’ can be used to illustrate and facilitate this investigation.
We argue that natural selection may have special status at an intermediate grain of analysis of evolutionary processes. The
cases of sickle-cell disease and genomic imprinting are used as case studies.
相似文献
Peter Godfrey-SmithEmail: |
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Roger Sansom 《Biology & philosophy》2008,23(4):475-491
I show that gene regulation networks are qualitatively consistent and therefore sufficiently similar to linearly seperable
connectionist networks to warrant that the connectionist framework be applied to gene regulation. On this view, natural selection
designs gene regulation networks to overcome the difficulty of development. I offer some general lessons about their evolvability
that can be learned by examining the generic features of connectionist networks.
相似文献
Roger SansomEmail: |