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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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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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Mathews KL Chapman SC Trethowan R Pfeiffer W van Ginkel M Crossa J Payne T Delacy I Fox PN Cooper M 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,115(6):819-835
The International Adaptation Trial (IAT) is a special purpose nursery designed to investigate the genotype-by-environment
interactions and worldwide adaptation for grain yield of Australian and CIMMYT spring bread wheat (Triticum aestivum L.) and durum wheat (T. turgidum L. var. durum). The IAT contains lines representing Australian and CIMMYT wheat breeding programs and was distributed to 91 countries between
2000 and 2004. Yield data of 41 reference lines from 106 trials were analysed. A multiplicative mixed model accounted for
trial variance heterogeneity and inter-trial correlations characteristic of multi-environment trials. A factor analytic model
explained 48% of the genetic variance for the reference lines. Pedigree information was then incorporated to partition the
genetic line effects into additive and non-additive components. This model explained 67 and 56% of the additive by environment
and non-additive by environment genetic variances, respectively. Australian and CIMMYT germplasm showed good adaptation to
their respective target production environments. In general, Australian lines performed well in south and west Australia,
South America, southern Africa, Iran and high latitude European and Canadian locations. CIMMYT lines performed well at CIMMYT’s
key yield testing location in Mexico (CIANO), north-eastern Australia, the Indo-Gangetic plains, West Asia North Africa and
locations in Europe and Canada. Maturity explained some of the global adaptation patterns. In general, southern Australian
germplasm were later maturing than CIMMYT material. While CIANO continues to provide adapted lines to northern Australia,
selecting for yield among later maturing CIMMYT material in CIANO may identify lines adapted to southern and western Australian
environments.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
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Ky L. Mathews (Corresponding author)Email: |
Scott C. ChapmanEmail: |
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Machado RR Lima Filho ES Jardim DF Ferreira MA de Faria CG Duarte RS Lesche B 《European biophysics journal : EBJ》2008,38(1):111-119
An interferometer that measures the refractive index changes due to bacterial metabolism is described. The apparatus permits
simultaneous and real time measurement of bacterial growth in several samples of slowly growing mycobacteria. The error sources
are discussed and the sensitivity of the apparatus is tested. For the species Mycobacterium bovis BCG and M. smegmatis, a relation between refractive index change and bacterial concentration is determined experimentally and the time constant
of bacterial growth is measured.
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B. LescheEmail: |
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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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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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Strategies of abstraction 总被引:2,自引:1,他引:1
Richard Levins 《Biology & philosophy》2006,21(5):741-755
Abstraction is seen as an active process which both enlightens and obscures. Abstractions are not true or false but relatively
enlightening or obscuring according to the problem under study; different abstractions may grasp different aspects of a problem.
Abstractions may be useless if they can answer questions only about themselves. A theoretical enterprise explores reality
through acluster of abstractions that use different perspectives, temporal and horizontal scales, and assumes different givens.
相似文献
Richard LevinsEmail: |
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Lisa Robins 《EcoHealth》2007,4(3):247-263
This paper examines capacity-building measures used by the health sector relevant to natural resource management (NRM) using
the delivery of two programs in Australia through its recently formalized 56 community-based regional NRM Boards as a reference
point. The delivery of NRM outcomes through devolved governance arrangements has been hampered by inadequate capacity in other
countries (e.g., New Zealand, Canada). The inherent complexities of NRM, coupled with professional “comfort zones,” often
limit actors from looking to other sectors confronting similar issues. This paper summarizes findings from ∼70 sources in
health reviewing nine major capacity-building measures. The outcomes of research evaluating the relative benefits and disbenefits
of applying these measures are discussed. The paper identifies several opportunities to trial some of these measures in NRM.
相似文献
Lisa RobinsEmail: |
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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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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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In this paper, we explore the role of reciprocity in the employment of restrictive measures in contexts of contagion. Reciprocity
should be understood as a substantive value that governs the use, level and extent of restrictive measures. We also argue
that independent of the role reciprocity plays in the legitimisation the use of restrictive measures, reciprocity can also
motivate support and compliance with legitimate restrictive measures. The importance of reciprocity has implications for how
restrictive measures should be undertaken when preparing and evaluating public health responses to contagion.
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A. M. ViensEmail: |
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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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We develop a formal framework for the optimal allocation of limited resources that includes and clarifies the interplay between
individual optimization and the resulting effects at the population level. As an example, in regard to the evolution of sexual
recombination, the paradox of the twofold cost of sex is avoided by distinguishing between the evolution of recombination
and the subsequent emergence and stability of different mating types as a result of individual optimization within a population
that benefits from recombination.
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John PepperEmail: |
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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.
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Ram PanditEmail: |