共查询到20条相似文献,搜索用时 15 毫秒
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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: |
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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.
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Peter Godfrey-SmithEmail: |
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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: |
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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: |
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Causal Explanation of Indonesian Forest Fires: Concepts, Applications, and Research Priorities 总被引:1,自引:0,他引:1
Andrew P. Vayda 《Human ecology: an interdisciplinary journal》2006,34(5):615-635
Problems with studies, claims, and assumptions that have been made about the causes of fires in Indonesia's tropical moist forests are identified, and the kinds of concepts, methods, prioritizing, and data needed to resolve the problems are discussed. Separate sections are devoted to studying ignitions, studying fire susceptibility and fire behavior, and using the goal of causal explanation to guide interdisciplinary research.
相似文献
Andrew P. VaydaEmail: |
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Threatened species and the spatial concentration of humans 总被引:1,自引:1,他引:0
Public policies that encourage high-density human living arrangements have been predicated explicitly on the assumption that
certain spatial distributions of a fixed-size human population are less environmentally damaging than others. We examine the
empirical validity of this assumption across 127 countries by analyzing whether the concentration of human presence in each
country is related statistically to the percentage of species that were on the IUCN Red List in 2004. Our findings indicate
that concentration of the human population is associated with reduced imperilment among amphibians but increased imperilment
among reptiles, and birds.
相似文献
Ram PanditEmail: |
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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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Methanogens growing on C-1 substrates synthesize 2-carbon acetyl groups in the form of acetyl-CoA for carbon assimilation
using the multienzyme complex acetyl-CoA decarbonylase/synthase (ACDS) which contains five different subunits encoded within
an operon. In species growing on acetate ACDS also functions to cleave the acetate C-C bond for energy production by methanogenesis.
A number of species of Methanosarcina that are capable of growth on either C-1 compounds or acetate contain two separate ACDS operons, and questions have been
raised about whether or not these operons play separate roles in acetate synthesis and cleavage. Methanosarcina thermophila genomic DNA was analyzed for the presence of two ACDS operons by PCR amplifications with different primer pairs, restriction
enzyme analyses, DNA sequencing and Southern blot analyses. A single ACDS operon was identified and characterized, with no
evidence for more than one. MALDI mass spectrometric analyses were carried out on ACDS preparations from methanol- and acetate-grown
cells. Peptide fragmentation patterns showed that the same ACDS subunits were present regardless of growth conditions. The
evidence indicates that a single form of ACDS is used both for acetate cleavage during growth on acetate and for acetate synthesis
during growth on C-1 substrates.
Electronic Supplementary Material Supplementary material is available for this article at
相似文献
David A. Grahame (Corresponding author)Email: |
Edward DeMoll (Corresponding author)Email: |
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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: |
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Studies on the effects of a variety of exogenous and anthropogenic environmental factors, including endocrine disruptors,
heavy metals, UV light, high temperature, and others, on marine organisms have been presented at the 2nd Bilateral Seminar
Italy–Japan held in November 2006. Reports were discussed in order to reveal the current situation of marine ecosystems, aiming
at evaluation and prediction of environmental risks.
相似文献
V. MatrangaEmail: |
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Jane E. Schultz 《Journal of bioethical inquiry》2007,4(2):93-102
In researching the biomedically-engineered drug Neulasta (filgrastim), a breast cancer patient becomes aware of the extent
to which knowledge about the development and marketing of drugs influences her decisions with regard to treatment. Time spent
on understanding the commercial interests of insurers and pharmaceutical companies initially thwarts but ultimately aids the
healing process. This first-person narrative calls for physicians to recognize that the alignment of commercial interests
transgresses the patient’s humanity.
相似文献
Jane E. SchultzEmail: |
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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: |
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Leslie P. Francis Margaret P. Battin Jay Jacobson Charles Smith 《Journal of bioethical inquiry》2009,6(2):187-195
Syndromic surveillance uses new ways of gathering data to identify possible disease outbreaks. Because syndromic surveillance
can be implemented to detect patterns before diseases are even identified, it poses novel problems for informed consent, patient
privacy and confidentiality, and risks of stigmatization. This paper analyzes these ethical issues from the viewpoint of the
patient as victim and vector. It concludes by pointing out that the new International Health Regulations fail to take full
account of the ethical challenges raised by syndromic surveillance.
相似文献
Leslie P. FrancisEmail: |
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Renuka M. Sharma 《Journal of bioethical inquiry》2007,4(3):181-192
This paper discusses the persistent devaluation of the girl child in India and the link between the entrenched perception
of female valuelessness and the actual practice of infanticide of girl babies or foetuses. It seeks to place female infanticide,
or ‘gendercide,’ within the context of Western-derived conceptions of ethics, justice and rights. To date, current ethical
theories and internationally purveyed moral frameworks, as well as legal and political declarations, have fallen short of
an adequate moral appraisal of infanticide. This paper seeks to rethink the issue.
相似文献
Renuka M. SharmaEmail: |
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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: |