211 research outputs found
The use of the stable oxygen isotope (18O) to trace the distribution and uptake of water in riparian woodlands
Streamside vegetation forming narrow "corridors" in temperate regions, is typically dominated by deciduous tree species reflecting strong influences by human activities. Riparian woodlands depend on hydrological resources and have to adapt to rapid changes in water levels and soil moisture conditions. Three main water sources are typically present in the riparian zone: river water originating in the mountains, ground water and rainfall. Stable isotopes, such as oxygen-18, are useful tools which allow for water movement to be traced within the riparian zone and which help to identify water sources utilised by the trees growing in these areas
The use of the stable oxygen isotope (180) to trace the distribution and uptake of water in riparian woodlands
International audienceStreamside vegetation forming narrow “corridors” in temperate regions, is typically dominated by deciduous tree species reflecting strong influences by human activities. Riparian woodlands depend on hydrological resources and have to adapt to rapid changes in water levels and soil moisture conditions. Three main water sources are typically present in the riparian zone: river water originating in the mountains, ground water and rainfall. Stable isotopes, such as oxygen 18, are useful tools which allow for water movement to be traced within the riparian zone and which help to identify water sources utilised by the trees growing in these areas
The use of the stable oxygen isotope (180) to trace the distribution and uptake of water riparian woodlands
Streamside vegetation forming narrow “corridors” in temperate regions, is typically dominated by deciduous tree species reflecting strong influences by human activities. Riparian woodlands depend on hydrological resources and have to adapt to rapid changes in water levels and soil moisture conditions. Three main water sources are typically present in the riparian zone: river water originating in the mountains, ground water and rainfall. Stable isotopes, such as oxygen 18, are useful tools which allow for water movement to be traced within the riparian zone and which help to identify water sources utilised by the trees growing in these areas
Analyse de la relation entre le revenu et la mortalité : un commentaire méthodologique
La région urbaine de l’Outaouais (Gatineau) a un revenu moyen plus élevé que le Québec urbain; cependant, ses indicateurs de santé sont moins favorables. Cette situation, contraire à ce que l’on retrouve le plus souvent au niveau de la santé des populations, est désignée par l’expression « paradoxe outaouais ». Nous avons pu analyser l’impact des choix méthodologiques sur l’évaluation de la relation entre le revenu et la santé, au niveau de la ville et au niveau du quintile de revenu. Selon que l’unité de référence est le Québec urbain ou la RMR Ottawa-Gatineau, le paradoxe se réalise ou disparaît. Selon la partition utilisée, le gradient de l’espérance de vie ainsi que l’écart entre Ottawa et Gatineau varient de manière appréciable. Nos résultats montrent que les choix méthodologiques jouent un rôle important et doivent par conséquent être faits avec soin.The Outaouais urban area (Gatineau) has a higher average income compared to the rest of urban Quebec, but its health indicators are less favourable. This situation, contrary to what is usually expected for population health, has been called “the Outaouais paradox”. We have been able to analyse the impact of methodological choices on the evaluation of the relationship between income and health, at the city level and at the income quintile level. If the reference unit is urban Quebec the paradox appears, but if the reference unit is the Ottawa-Gatineau CMA, the paradox disappears. Depending on the partition used, the life expectancy gradient as well as the gap between Ottawa and Gatineau differ substantially. Our results show that methodological choices play an important role and must thus be done cautiously
Myths and lessons of liberal intervention: The British campaign for the abolition of the Atlantic slave trade to Brazil
This is the Pre-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2012 Martinus NijhoffThis article takes issue with recent references to the British nineteenth century campaign for the abolition of the trans-Atlantic slave trade to Brazil that serve to bolster interventionist or imperialist agendas. In particular, such accounts reproduce two and a half myths about the campaign: that it can serve as a model for the present age; that the success of the campaign can be explained through the actions of the intervening party alone (with a corresponding neglect of those of the ‘target’ state); and the half-myth that the campaign’s success was due to military action (at the expense of institutional (legal) and normative factors and the capacity of the target state). I argue instead that this case – and interventions more generally – would benefit from an analysis that considers the role of force in relation to a series of residual institutional and cultural constraints within the liberal state and to political conditions in the target state. In light of the complexities and contingencies that these factors present the underlying lesson is that military force should be used sparingly, if at all
Spontaneous hot-electron light emission from electron-fed optical antennas
Nanoscale electronics and photonics are among the most promising research
areas providing functional nano-components for data transfer and signal
processing. By adopting metal-based optical antennas as a disruptive
technological vehicle, we demonstrate that these two device-generating
technologies can be interfaced to create an electronically-driven self-emitting
unit. This nanoscale plasmonic transmitter operates by injecting electrons in a
contacted tunneling antenna feedgap. Under certain operating conditions, we
show that the antenna enters a highly nonlinear regime in which the energy of
the emitted photons exceeds the quantum limit imposed by the applied bias. We
propose a model based upon the spontaneous emission of hot electrons that
correctly reproduces the experimental findings. The electron-fed optical
antennas described here are critical devices for interfacing electrons and
photons, enabling thus the development of optical transceivers for on-chip
wireless broadcasting of information at the nanoscale
A combination of methotrexate and zoledronic acid prevents bone erosions and systemic bone mass loss in collagen induced arthritis
Introduction Osteoclasts play a key role in the pathogenesis of
bone erosion and systemic bone mass loss during rheumatoid
arthritis (RA). In this study, we aimed to determine the effect of
methotrexate (MTX) and zoledronic acid (ZA), used alone or in
combination, on osteoclast-mediated bone erosions and
systemic bone mass loss in a rat model of collagen induced
arthritis (CIA). We hypothesized that MTX and ZA could have an
additive effect to prevent both bone erosion and systemic bone
loss.
Methods Arthritis was induced in 64 female Sprague-Dawley
rats. After the clinical onset of CIA, rats were assigned to
treatment with MTX (1 mg/kg/week), ZA (100 μg/kg twice
weekly), both treatments at the same regimens, or vehicle.
Arthritis score and paw thickness were recorded twice weekly.
The rats were sacrificed on D28 and hind paws were removed
for radiographic, histological and immunohistochemical
analysis. The effects of treatments on osteoclastogenesis were
determined by Tartrate resistant acid phosphatase (TRAP)
staining. Micro-CT of the tibia was carried out for
histomorphometric analysis. Bone mass density was evaluated
by densitometry.
Results MTX significantly decreased the severity of CIA,
whereas ZA slightly exacerbated it. When these two drugs were
used in combination, MTX prevented the pro-inflammatory effect
of ZA. The combination of ZA with MTX was more effective than
MTX alone for reducing structural joint damage with a dramatic
decrease of osteoclasts' number in the eroded joints. However,
MTX alone also significantly reduced the number of osteoclasts
and the number of CD68+ mononuclear cells. ZA alone, or ZA
with MTX, significantly increased the systemic bone mass
density measured by densitometry and bone volume on
histomorphometric analysis.
Conclusions A combination of MTX and ZA prevented both
bone erosion and systemic bone loss in a rat model of arthritis.
Both treatments independently decreased the number of
osteoclasts in the eroded joint. However, while MTX probably
acts mainly through a decrease of inflammation, ZA has a direct
effect on osteoclasts, allowing a dramatic down-regulation of
these cells in inflamed joints. These two different mechanisms of
action provide support for the use of a combination of these two
drugs to improve the prevention of structural joint damage in RA
Impact of classic and paradoxical low flow on survival after aortic valve replacement for severe aortic stenosis
BackgroundLow flow (LF) can occur with reduced (classic) or preserved (paradoxical) left ventricular ejection fraction (LVEF). ObjectivesThe objective of this study was to compare outcomes of patients with low ejection fraction (LEF), paradoxical low flow (PLF), and normal flow (NF) after aortic valve replacement (AVR). MethodsWe examined 1,154 patients with severe aortic stenosis (AS) who underwent AVR with or without coronary artery bypass grafting. ResultsAmong these patients, 206 (18%) had LEF as defined by LVEF of 35 ml · m2. Aortic valve area was lower in low flow/LVEF groups (LEF: 0.71 ± 0.20 cm2 and PLF: 0.65 ± 0.23 cm2 vs. NF: 0.77 ± 0.18 cm2; p < 0.001). The 30-day mortality was higher (p < 0.001) in LEF and PLF groups than in the NF group (6.3% and 6.3% vs. 1.8%, respectively). SVi and PLF group were independent predictors of operative mortality (odds ratio [OR]: 1.18, p < 0.05; and OR: 2.97, p = 0.004; respectively). At 5 years after AVR, overall survival was 72 ± 4% in LEF group, 81 ± 2% in PLF group, and 85 ± 2% in NF group (p < 0.0001). ConclusionsPatients with LEF or PLF AS have a higher operative risk, but pre-operative risk score accounted only for LEF and lower LVEF. Patients with LEF had the worst survival outcome, whereas patients with PLF and normal flow had similar survival rates after AVR. As a major predictor of perioperative mortality, SVi should be integrated in AS patients’ pre-operative evaluation
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