共查询到20条相似文献,搜索用时 78 毫秒
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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.
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Marienne S. de VilliersEmail: Fax: +27-21-6503434 |
John CooperEmail: |
Peter G. RyanEmail: |
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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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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.
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V. MatrangaEmail: |
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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: |
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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.
相似文献
Peter Godfrey-SmithEmail: |
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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.
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Terry HarmerEmail: |
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Coral reef marine protected areas (MPA) are widely distributed around the globe for social and ecological reasons. Relatively
few of these MPAs are well managed. This review examines the governance of coral reef MPAs and the means to improve coral
reef MPA management. It highlights common governance challenges, such as confused goals, conflict, and unrealistic attempts
to scale up beyond institutional capacity. Recommendations, based on field experience and empirical evidence from around the
world, are made for best practices at various stages of MPA implementation.
相似文献
A. T. WhiteEmail: |
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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.
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Laurent Tournier (Corresponding author)Email: |
Jean-Luc GouzéEmail: |
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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.
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Andrew P. VaydaEmail: |
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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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Previous studies have indicated that microbubbles prepared by co-axial electrohydrodynamic atomisation (CEHDA) are less stable
than those prepared by other methods such as sonication and microfluidic techniques. The aim of this investigation was to
determine the reasons for this observation and how this might be addressed in future work. Microbubbles were prepared by CEHDA
using (i) a glycerol–air system, (ii) a glycerol–Tween 80–air system and (iii) a glycerol–zirconia–air system and also by
simple agitation of (i) and (ii), in order to compare the effect upon the dissolution rate of microbubbles of different materials
and processing methods. Both theoretical examination and the experimental results indicated that all three quantities were
important in controlling the rate of microbubble dissolution, namely: surface tension at the gas/liquid interface, the effective
diffusivity of gas through this interface and the initial concentration of gas dissolved in the surrounding liquid. However,
it was the difference in gas concentration in the surrounding liquid that was indicated as the primary reason for the differences
in stability observed with different processing methods. It was concluded, therefore, that improved stability could be achieved
for microbubbles prepared using CEHDA by saturating the collecting fluid with gas and/or maintaining a high concentration
of microbubbles during collection.
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Eleanor StrideEmail: |
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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
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David A. Grahame (Corresponding author)Email: |
Edward DeMoll (Corresponding author)Email: |
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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: |
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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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Sahotra Sarkar 《Biology & philosophy》2008,23(2):217-228
On the basis of distinctions between those properties of entities that can be defined without reference to other entities
and those that (in different ways) cannot, this note argues that non-trivial forms of frequency-dependent selection of entities
should be interpreted as selection occurring at a level higher than that of those entities. It points out that, except in
degenerately simple cases, evolutionary game-theoretic models of selection are not models of individual selection. Similarly,
models of genotypic selection such as heterosis cannot be legitimately interpreted as models of genic selection. The analysis
presented here supports the views that: (i) selection should be viewed as a multi-level process; (ii) upper-level selection
is ubiquitous; (iii) kin selection should be viewed as a type of group selection rather than individual selection; and (iv)
inclusive fitness is not an individual property.
相似文献
Sahotra SarkarEmail: |
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Cell division in tissues can be investigated in various ways. We present here a method for improving cell recovery and cell
cycle analysis for a wide range of mouse tissues. This strategy combines a cell isolation procedure for various mouse tissues
based on intracardiac perfusion and subsequent treatment followed by flow cytometry. This easy and reproducible method allows
a rapid analysis of nuclear DNA content, providing an estimate of the cell number at different phases of the cell cycle. This
combined procedure could also be used for the isolation of specific cell subpopulations from different mouse tissues by fluorescence
activated cell sorting.
相似文献
Geneviève GourdonEmail: |