共查询到20条相似文献,搜索用时 31 毫秒
1.
Large-scale scientific computing applications frequently make use of closely-coupled distributed parallel components. The
performance of such applications is therefore dependent on the component parts and their interaction at run-time. This paper
describes a methodology for predictive performance modelling and evaluation of parallel applications composed of multiple
interacting components. In this paper, the fundamental steps and required operations involved in the modelling and evaluation
process are identified—including component decomposition, component model combination, M×N communication modelling, dataflow analysis and overall performance evaluation. A case study is presented to illustrate the
modelling process and the methodology is verified through experimental analysis.
相似文献
Stephen A. JarvisEmail: |
2.
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: |
3.
Anya Plutynski 《Biology & philosophy》2008,23(5):605-623
The discussion of the adaptive landscape in the philosophical literature appears to be divided along the following lines.
On the one hand, some claim that the adaptive landscape is either “uninterpretable” or incoherent. On the other hand, some
argue that the adaptive landscape has been an important heuristic, or tool in the service of explaining, as well as proposing
and testing hypotheses about evolutionary change. This paper attempts to reconcile these two views.
相似文献
Anya PlutynskiEmail: |
4.
In this paper we review and argue for the relevance of the concept of open-ended evolution in biological theory. Defining
it as a process in which a set of chemical systems bring about an unlimited variety of equivalent systems that are not subject
to any pre-determined upper bound of organizational complexity, we explain why only a special type of self-constructing, autonomous
systems can actually implement it. We further argue that this capacity derives from the ‘dynamic decoupling’ (in its minimal
or most basic sense: the phenotype–genotype decoupling) by means of which a radically new way of material organization (minimal
living organization) is achieved, allowing for the long-term sustenance of systems whose individual-metabolic and collective-historical
pathways become thereafter deeply intertwined.
相似文献
Kepa Ruiz-MirazoEmail: |
5.
Patrick Forber 《Biology & philosophy》2009,24(2):247-266
Evolutionary biology, indeed any science that attempts to reconstruct prehistory, faces practical limitations on available
data. These limitations create the problem of contrast failure: specific observations may fail to discriminate between rival evolutionary hypotheses. Assessing the risk of contrast failure
provides a way to evaluate testing protocols in evolutionary science. Here I will argue that part of the methodological critique
in the Spandrels paper involves diagnosing contrast failure problems. I then distinguish the problem of contrast failure from the more familiar
philosophical problem of underdetermination, and demonstrate how contrast failure arises in scientific practice with an investigation
into Lewontin and White’s (Evolution 14:116–129, 1960) estimation of an adaptive landscape.
相似文献
Patrick ForberEmail: |
6.
7.
Jay Odenbaugh 《Biology & philosophy》2006,21(5):607-621
In this essay, I argue for four related claims. First, Richard Levins’ classic “The Strategy of Model Building in Population
Biology” was a statement and defense of theoretical population biology growing out of collaborations between Robert MacArthur,
Richard Lewontin, E. O. Wilson, and others. Second, I argue that the essay served as a response to the rise of systems ecology
especially as pioneered by Kenneth Watt. Third, the arguments offered by Levins against systems ecology and in favor of his
own methodological program are best construed as “pragmatic”. Fourth, I consider limitations of Levins’ arguments given contemporary
population biology.
相似文献
Jay OdenbaughEmail: |
8.
The distinction between personal level explanations and subpersonal ones has been subject to much debate in philosophy. We
understand it as one between explanations that focus on an agent’s interaction with its environment, and explanations that
focus on the physical or computational enabling conditions of such an interaction. The distinction, understood this way, is
necessary for a complete account of any agent, rational or not, biological or artificial. In particular, we review some recent
research in Artificial Life that pretends to do completely without the distinction, while using agent-centred concepts all
the way. It is argued that the rejection of agent level explanations in favour of mechanistic ones is due to an unmotivated
need to choose among representationalism and eliminativism. The dilemma is a false one if the possibility of a radical form
of externalism is considered.
相似文献
Jason NobleEmail: |
9.
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: |
10.
T. Ryan Gregory 《Evolution》2009,2(2):156-175
Natural selection is one of the central mechanisms of evolutionary change and is the process responsible for the evolution
of adaptive features. Without a working knowledge of natural selection, it is impossible to understand how or why living things
have come to exhibit their diversity and complexity. An understanding of natural selection also is becoming increasingly relevant
in practical contexts, including medicine, agriculture, and resource management. Unfortunately, studies indicate that natural
selection is generally very poorly understood, even among many individuals with postsecondary biological education. This paper
provides an overview of the basic process of natural selection, discusses the extent and possible causes of misunderstandings
of the process, and presents a review of the most common misconceptions that must be corrected before a functional understanding
of natural selection and adaptive evolution can be achieved.
相似文献
T. Ryan GregoryEmail: |
11.
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: |
12.
W. Tecumseh Fitch 《Biology & philosophy》2008,23(2):157-177
I suggest that most discussions of intentional systems have overlooked an important aspect of living organisms: the intrinsic
goal-directedness inherent in the behaviour of living eukaryotic cells. This goal directedness is nicely displayed by a normal
cell’s ability to rearrange its own local material structure in response to damage, nutrient distribution or other aspects
of its individual experience. While at a vastly simpler level than intentionality at the human cognitive level, I propose
that this basic capacity of living things provides a necessary building block for cognition and high-order intentionality,
because the neurons that make up vertebrate brains, like most cells in our body, embody such capacities. I provisionally dub
the capacities in question “nano-intentionality”: a microscopic form of “aboutness”. The form of intrinsic intentionality
I propose is thoroughly materialistic, fully compatible with known biological facts, and derived non-mysteriously through
evolution. Crucially, these capacities are not shared by any existing computers or computer components, and thus provide a
clear, empirically-based distinction between brains and currently existing artificial information processing systems. I suggest
that an appreciation of this aspect of living matter provides a potential route out of what may otherwise appear to be a hopeless
philosophical quagmire confronting information-processing models of the mind.
相似文献
W. Tecumseh FitchEmail: |
13.
The widespread deployment of the advanced computer technology in business and industries has demanded the high standard on
quality of service (QoS). For example, many Internet applications, i.e. online trading, e-commerce, and real-time databases,
etc., execute in an unpredictable general-purpose environment but require performance guarantees. Failure to meet performance
specifications may result in losing business or liability violations. As systems become distributed and complex, it has become
a challenge for QoS design. The ability of on-line identification and auto-tuning of adaptive control systems has made the
adaptive control theoretical design an attractive approach for QoS design. However, there is an inherent constraint in adaptive
control systems, i.e. a conflict between asymptotically good control and asymptotically good on-line identification. This
paper first identifies and analyzes the limitations of adaptive control for network QoS by extensive simulation studies. Secondly,
as an approach to mitigate the limitations, we propose an adaptive dual control framework. By incorporating the existing uncertainty
of on-line prediction into the control strategy and accelerating the parameter estimation process, the adaptive dual control
framework optimizes the tradeoff between the control goal and the uncertainty, and demonstrates robust and cautious behavior.
The experimental study shows that the adaptive dual control framework mitigate the limitations of the conventional adaptive
control framework. Compared with the conventional adaptive control framework under the medium uncertainty, the adaptive dual
control framework reduces the deviation from the desired hit-rate ratio from 40% to 13%.
相似文献
Haowei BaiEmail: |
14.
Catherine Driscoll 《Biology & philosophy》2008,23(1):101-113
This paper tries to explain how individuals manage adaptive individual choice (i.e., the decision to acquire a fitter than
average behavior or idea rapidly and tractably) in cultural evolution, despite the fact that acquiring fitness information
is very difficult. I argue that the means of solving this problem suggested in the cultural evolution literature largely are
various types of decision rules employing representations of fitness correlated properties or states of affairs. I argue that
the problem of adaptive individual choice is best solved where some of these learning rule representations are socially transmitted
and some are biologically transmitted.
相似文献
Catherine DriscollEmail: |
15.
16.
The interconnection network is one of the key architectural components in any parallel computer. The distribution of the traffic
injected into the network is among the factors that greatly influences network performance. The uniform traffic pattern has
been adopted in many existing network performance evaluation studies due to the tractability of the resulting analytical modelling
approach. However, many real applications exhibit non-uniform traffic patterns such as hot-spot traffic. K-ary n-cubes have been the mostly widely used in the implementation of practical parallel systems. Extensive research studies have
been conducted on the performance modelling and evaluation of these networks. Nonetheless, most of these studies have been
confined to uniform traffic distributions and have been based on software simulation. The present paper proposes a new stochastic
model to predict message latency in k-ary
n-cubes with deterministic routing in the presence of hot-spot traffic. The model has been validated through simulation experiments
and has shown a close agreement with simulation results.
相似文献
Geyong MinEmail: |
17.
18.
19.
James Carney 《Biosemiotics》2008,1(3):313-327
The basic premise of biosemiotics as a discipline is that there are elementary processes linking signifying strategies in
all forms of animate life. Correspondingly, the discoveries of biosemiotics should, in principle, be capable of revealing
new insights about human signification. In the present article, I show that this is in fact the case by constructing a biosemiotic
model that links advertising strategies with corresponding structures in animal predation. The methodological framework for
this model is the catastrophe theory of René Thom. The end result is a revised understanding of an ostensibly cultural phenomenon
that demonstrates its continuity with signalling processes conventionally associated with the natural world.
相似文献
James CarneyEmail: |
20.
We propose a principle of consistency between different hierarchical levels of biological systems. Given a consistency between
molecule replication and cell reproduction, universal statistical laws on cellular chemical abundances are derived and confirmed
experimentally. They include a power law distribution of gene expressions, a lognormal distribution of cellular chemical abundances
over cells, and embedding of the power law into the network connectivity distribution. Second, given a consistency between
genotype and phenotype, a general relationship between phenotype fluctuations by genetic variation and isogenic phenotypic
fluctuation by developmental noise is derived. Third, we discuss the chaos mechanism for stem cell differentiation with autonomous
regulation, resulting from a consistency between cell reproduction and growth of the cell ensemble.
相似文献
Kunihiko KanekoEmail: |