共查询到20条相似文献,搜索用时 62 毫秒
1.
Following the methodology of K. F. Huemmrich and colleagues [Huemmrich et al. (1999) J Geophys Res 104:27,935–27,944], agrometeorological
standard radiation sensors, i.e. two photosynthetically active radiation sensors and an albedometer, were used to measure
the broadband visible and optical–infrared reflectance of an oat plot during its whole growth period. From these reflectance
data – recorded as 15-min averages and pooled to daily means – the seasonal cycle of the normalised difference vegetation
index (NDVI) was calculated. In addition, a ground-based multi-channel spectroradiometer was used as a reference to estimate
narrowband “green” and “red” NDVIs at weekly intervals near noon. The narrowband “green” NDVI was shown to be consistent with
the simultaneous broadband 15-min NDVI. This shows that the configuration of agrometeorological radiation sensors is suitable
to adequately track phenological crop dynamics.
相似文献
Martin KraftEmail: |
2.
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: |
3.
4.
Albert Pèlachs Jordi Nadal Joan Manuel Soriano David Molina Raquel Cunill 《Vegetation History and Archaeobotany》2009,18(5):403-416
This research is based on the discovery of a large number of charcoal kiln sites and abandoned iron mines in Vallferrera (Axial
Pyrenees, northeastern Spain). The study reveals that this region has been affected by the metal mining and smelting industry
for at least 2,000 years, with maximum intensity in the eighteenth and nineteenth centuries, followed by abandonment of the
activity. The region’s woodland dendrochronology and historical records indicate that exploitation of wood charcoal for metalworking
affected the past vegetation in the area and impeded the development of mature woodland. Our findings suggest that the greatest
changes in vegetation and landscape history occurred at times of particular specialization in socioeconomic activities.
相似文献
Albert PèlachsEmail: |
5.
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: |
6.
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.
相似文献
B. LescheEmail: |
7.
8.
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: |
9.
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: |
10.
Great Barrier Island (c. 27,400 ha) is the largest off-shore Island in New Zealand. Some of the most serious introduced mammalian
pests of New Zealand are absent, but feral cats and rodents are present. Community based trusts are spear-heading ecological
studies to support conservation and a pest eradication programme. Rodent numbers are greatest in late summer/autumn and lowest
in winter/early spring. Maximum abundances were recorded in riparian and coastal vegetation, and in mature forest. Monitoring
shows that trapping alone is not able to reduce rat numbers sufficiently for safety in avian re-introductions. A combination
of trapping and strategically pulsed toxin baits, however, achieved low levels of rats. Ecosystem recovery is demonstrated
by increases in key tree seedlings, large invertebrates and lizards in managed compared to unmanaged areas, and by the survivorship
of translocated robins (Petroica longipes). The Great Barrier Island Charitable Trust is communicating these benefits, and associated risks, to the Island community,
with a view to promoting pest eradication as a key component in an ecology-based economy, centred on eco-tourism.
相似文献
Judy GilbertEmail: |
11.
Robert Carlson 《Systems and synthetic biology》2007,1(3):109-117
Biological technologies are becoming an important part of the economy. Biotechnology already contributes at least 1% of US
GDP, with revenues growing as much as 20% annually. The introduction of composable biological parts will enable an engineering
discipline similar to the ones that resulted in modern aviation and information technology. As the sophistication of biological
engineering increases, it will provide new goods and services at lower costs and higher efficiencies. Broad access to foundational
engineering technologies is seen by some as a threat to physical and economic security. However, regulation of access will
serve to suppress the innovation required to produce new vaccines and other countermeasures as well as limiting general economic
growth.
相似文献
Robert CarlsonEmail: |
12.
Peter Olofsson 《Biology & philosophy》2008,23(4):545-553
The explanatory filter is a proposed method to detect design in nature with the aim of refuting Darwinian evolution. The explanatory filter borrows
its logical structure from the theory of statistical hypothesis testing but we argue that, when viewed within this context,
the filter runs into serious trouble in any interesting biological application. Although the explanatory filter has been extensively
criticized from many angles, we present the first rigorous criticism based on the theory of mathematical statistics.
相似文献
Peter OlofssonEmail: |
13.
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: |
14.
J. Stephen Athens 《Biological invasions》2009,11(7):1489-1501
Paleoenvironmental and archaeological investigations from the ’Ewa Plain of O’ahu provide insight into the problem of understanding
lowland native forest loss in Hawai’i. Data from pollen analysis of a pond core record, avian paleontology, and archeology,
document a precipitous decline of the native forest starting before Polynesian settlement on the ’Ewa Plain but after Polynesian
colonization of O’ahu. It is hypothesized that rats, introduced by Polynesian colonizers, increased exponentially in the absence
of significant predators or competitors, feeding on a largely endemic vegetation that had evolved in the absence of mammalian
predators. Rats radiated ahead of human colonizers on O’ahu, eating their way through the vegetation, perhaps before the colonizers
had encountered much of the pristine lowland forest into which the rats had radiated. This hypothesis is supported by several
observations, including the almost complete absence of extinct or extirpated avian faunal remains in archaeological deposits,
the present distribution of endemic vegetation in Hawai’i, rat ecology, population biology, and other evidence.
相似文献
J. Stephen AthensEmail: |
15.
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: |
16.
Alejandro Rosas 《Biology & philosophy》2008,23(4):555-566
Recent developments in evolutionary game theory argue the superiority of punishment over reciprocity as accounts of large-scale
human cooperation. I introduce a distinction between a behavioral and a psychological perspective on reciprocity and punishment
to question this view. I examine a narrow and a wide version of a psychological mechanism for reciprocity and conclude that a narrow version is clearly distinguishable from punishment, but inadequate for
humans; whereas a wide version is applicable to humans but indistinguishable from punishment. The mechanism for reciprocity
in humans emerges as a meta-norm that governs both retaliation and punishment. I make predictions open to empirical investigation
to confirm or disconfirm this view.
相似文献
Alejandro RosasEmail: |
17.
Oscillatory phenomena have been a focus of dynamical systems research since the time of the classical studies on the pendulum
by Galileo. Fast cortical oscillations also have a long and storied history in neurophysiology, and olfactory oscillations
have led the way with a depth of explanation not present in the literature of most other cortical systems. From the earliest
studies of odor-evoked oscillations by Adrian, many reports have focused on mechanisms and functional associations of these
oscillations, in particular for the so-called gamma oscillations. As a result, much information is now available regarding
the biophysical mechanisms that underlie the oscillations in the mammalian olfactory system. Recent studies have expanded
on these and addressed functionality directly in mammals and in the analogous insect system. Sub-bands within the rodent gamma
oscillatory band associated with specific behavioral and cognitive states have also been identified. All this makes oscillatory
neuronal networks a unique interdisciplinary platform from which to study neurocognitive and dynamical phenomena in intact,
freely behaving animals. We present here a summary of what has been learned about the functional role and mechanisms of gamma
oscillations in the olfactory system as a guide for similar studies in other cortical systems.
相似文献
Leslie M. KayEmail: |
18.
Density functional theoretical studies of monooxygenation reactivity of the high-valent oxoiron(IV) porphyrin cation-radical compound of cytochrome P450, the so-called Compound I, and of its precursor, the ferric(III)-hydroperoxide species, are described. The degeneracy of the spin states of Compound I, its electron deficiency, and dense orbital manifold lead to two-state and multi-state reactivity scenarios and may thereby create reactivity patterns as though belonging to two or more different oxidants. Most of the controversies in the experimental data are reconciled using Compound I as the sole competent oxidant. Theory finds ferric(III)-hydroperoxide to be a very sluggish oxidant, noncompetitive with Compound I. If and when Compound I is absent, P450 oxidation will logically proceed by another form, but this has to be more reactive than ferric(III)-hydroperoxide. Theoretical studies are conducted to pinpoint such an oxidant for P450.
相似文献
Sason ShaikEmail: Phone: +972-2-6585909Fax: +972-2-6584680 |
19.
This paper examines the biosemiotic approach to the study of life processes by fashioning a series of questions that any worthwhile
semiotic study of life should ask. These questions can be understood simultaneously as: (1) questions that distinguish a semiotic
biology from a non-semiotic (i.e., reductionist–physicalist) one; (2) questions that any student in biosemiotics should ask
when doing a case study; and (3) still currently unanswered questions of biosemiotics. In addition, some examples of previously
undertaken biosemiotic case studies are examined so as to suggest a broad picture of how such a biosemiotic approach to biology
might be done.
相似文献
Donald FavareauEmail: |
20.
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: |