共查询到20条相似文献,搜索用时 31 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.
相似文献
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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Natalia V. Ivanova Aron J. Fazekas Paul D. N. Hebert 《Plant Molecular Biology Reporter》2008,26(3):186-198
Many plant species are considered difficult for DNA isolation due to their high concentrations of secondary metabolites such
as polysaccharides and polyphenols. Several protocols have been developed to overcome this problem, but they are typically
time-consuming, not scalable for high throughput and not compatible with automation. Although a variety of commercial kits
are available for plant DNA isolation, their cost is high and these kits usually have limited taxonomic applicability. In
a previous study we developed an inexpensive automation-friendly protocol for DNA extraction from animal tissues. Here we
demonstrate that a similar protocol allows DNA isolation from plants.
相似文献
Natalia V. IvanovaEmail: |
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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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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.
相似文献
Terry HarmerEmail: |
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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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This study focuses on community-based knowledge to analyze the impacts of range enclosures, crop farming, fire suppression
and bush encroachment on the communal rangelands of Borana, southern Ethiopia. The knowledge of local herders is the basis
for decision making in the utilization and management of grazing lands. We used Borana oral history associated with the period
of the gada system to reconstruct environmental change that spans a period of 48 years. Our results show that the use of communities’
perceptions as a basis for evaluating the impacts of land use change on the environment makes an important methodological
contribution. Communities’ responses to changing land use resulted in the development of range enclosures, the expansion of
crop farming and the fragmentation of the communal rangelands, while the suppression of fire contributed to the expansion
of bush encroachment. The overall impact was forage scarcity and greater vulnerability of stock during drought years. We conclude
that policymakers could use communities’ knowledge of environmental change to improve the use of the rangelands. We propose
that sustainable use of the southern rangelands in the future will require a greater focus on regulating the expansion of
enclosures, crop farming and ranching, as well as reintroducing fire where necessary, to control the expansion of bush cover.
相似文献
Gufu ObaEmail: |
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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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Fabien Marpeau Aditya Barua Krešimir Josić 《Journal of computational neuroscience》2009,26(3):445-457
The stochastic integrate and fire neuron is one of the most commonly used stochastic models in neuroscience. Although some
cases are analytically tractable, a full analysis typically calls for numerical simulations. We present a fast and accurate
finite volume method to approximate the solution of the associated Fokker-Planck equation. The discretization of the boundary
conditions offers a particular challenge, as standard operator splitting approaches cannot be applied without modification.
We demonstrate the method using stationary and time dependent inputs, and compare them with Monte Carlo simulations. Such
simulations are relatively easy to implement, but can suffer from convergence difficulties and long run times. In comparison,
our method offers improved accuracy, and decreases computation times by several orders of magnitude. The method can easily
be extended to two and three dimensional Fokker-Planck equations.
相似文献
Fabien MarpeauEmail: |
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Skunkworks in the Embers of the Cedar Fire: Enhancing Resilience in the Aftermath of Disaster 总被引:2,自引:0,他引:2
Bruce Evan Goldstein 《Human ecology: an interdisciplinary journal》2008,36(1):15-28
A coalition of environmental activists and professionals created the San Diego Fire Recovery Network (SDFRN) while the largest
wildfire in California history was still burning at the city’s edge in October 2003. Acting quickly while the citizenry questioned
governmental ability to protect their rapidly growing region, SDFRN proposed to reduce fire risk in a way that altered residential
knowledge practices and identity while reshaping governance relationships. While this effort stalled after governmental agencies
restored public confidence through massive fire prevention initiatives, SDFRN’s efforts may not have been in vain. Retained
within collective memory, SDFRN contributed to community resilience by diversifying possible responses to environmental change
and uncertainty. In this way, flexible, informal learning organizations such as SDFRN may serve as “skunkworks,” seizing on
disaster in order to incubate social–ecological relationships that might avert greater tragedies to come.
相似文献
Bruce Evan GoldsteinEmail: |
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Frank R. Thomas 《Human ecology: an interdisciplinary journal》2007,35(2):179-194
Focusing on contemporary shellfish exploitation among several atoll communities in Kiribati, Micronesia, this paper examines
the relationship between human foragers and their invertebrate prey via the prey choice or diet breadth model derived from
optimal foraging theory. Shellfish, like many other reef organisms, are relatively sedentary and predictable, but these characteristics
make them susceptible to over-harvesting. The research reveals that shellfish gatherers are foraging in a manner that matches
the predictions of optimal foraging theory. The work adds to our understanding of optimal foraging decisions in atoll settings
by critically evaluating the depiction of atoll dwellers as conservationists.
相似文献
Frank R. ThomasEmail: Email: |
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In the Indian state of Goa, communally owned agricultural land has persisted through indigenous state rule, colonial occupation
and postcolonial liberation. We show that in Goa, and indeed elsewhere in the world, communally owned land provides protection
against scarcity, risk, and state revenue demands in wet rice agriculture. When wet rice agriculture is the primary agricultural
activity, communally owned land is an effective way to utilize resources. These findings add to the literature that challenges
the inevitability of the tragedy of commonly owned resources.
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Paul AxelrodEmail: |
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To our knowledge, this paper is the first record/report of a juvenile light-coloured Weddell seal (Leptonychotes weddellii) at Cape Shirreff, Livingston Island in January 1998, determining that it was an albino individual. Based on available literature,
three cases of albino seals have been reported exclusively for Harbour seal pups, and no albino has been reported for Antarctic
pagophilic true seals. Therefore, this is the first confirmed case of albinism in Antarctic pagophilic true seals species,
indicating that this phenomenon is indeed of a rare occurrence.
相似文献
Daniel TorresEmail: |
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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: |
20.
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: |