1,491 research outputs found
Having the Second Leg At Home - Advantage in the UEFA Champions League Knockout Phase?
In soccer knockout ties which are played in a two-legged format the team having the return match at home is usually seen as advantaged. For checking this common belief, we analyzed matches of the UEFA Champions League knockout phase since 1995. It is shown that the observed differences in frequencies of winning between teams first playing away and those which are first playing at home can be completely explained by their performances on the group stage and - more importantly - by the teams' general strength
The vertical structure of upper ocean variability at the Porcupine Abyssal Plain during 2012-2013
This study presents the characterization of variability in temperature, salinity and oxygen concentration, including the vertical structure of the variability, in the upper 1000m of the ocean over a full year in the northeast Atlantic. Continuously profiling ocean gliders with vertical resolution between 0.5-1m provide more information on temporal variability throughout the water column than time series from moorings with sensors at a limited number of fixed depths. The heat, salt and dissolved oxygen content are quantified at each depth. While the near surface heat content is consistent with the net surface heat flux, heat content of the deeper layers is driven by gyre-scale water mass changes. Below ~150m, heat and salt content display intraseasonal variability which has not been resolved by previous studies. A mode-1 baroclinic internal tide is detected as a peak in the power spectra of water mass properties. The depth of minimum variability is at ~415m for both temperature and salinity, but this is a depth of high variability for oxygen concentration. The deep variability is dominated by the intermittent appearance of Mediterranean Water, which shows evidence of filamentation. Susceptibility to salt fingering occurs throughout much of the water column for much of the year. Between about 700-900m, the water column is susceptible to diffusive layering, particularly when Mediterranean Water is present. This unique ability to resolve both high vertical and temporal resolution highlights the importance of intraseasonal variability in upper ocean heat and salt content, variations that may be aliased by traditional observing techniques
The mechanism of oxygen isotope fractionation during N2O production by denitrification
The isotopic composition of soil-derived N2O can help differentiate between N2O production pathways and estimate the fraction of N2O reduced to N2. Until now, δ18O of N2O has been rarely used in the interpretation of N2O isotopic signatures because of the rather complex oxygen isotope fractionations during N2O production by denitrification. The latter process involves nitrate reduction mediated through the following three enzymes: nitrate reductase (NAR), nitrite reductase (NIR) and nitric oxide reductase (NOR). Each step removes one oxygen atom as water (H2O), which gives rise to a branching isotope effect. Moreover, denitrification intermediates may partially or fully exchange oxygen isotopes with ambient water, which is associated with an exchange isotope effect. The main objective of this study was to decipher the mechanism of oxygen isotope fractionation during N2O production by denitrification and, in particular, to investigate the relationship between the extent of oxygen isotope exchange with soil water and the δ18O values of the produced N2O. We performed several soil incubation experiments. For the first time, ∆17 O isotope tracing was applied to simultaneously determine the extent of oxygen isotope exchange and any associated oxygen isotope effect. We found bacterial denitrification to be typically associated with almost complete oxygen isotope exchange and a stable difference in δ18O between soil water and the produced N2O of δ18O(N2O / H2O) = (17.5±1.2) ‰. However, some experimental setups yielded oxygen isotope exchange as low as 56 % and a higher δ18O(N2O / H2O) of up to 37‰. The extent of isotope exchange and δ18O(N2O / H2O) showed a very significant correlation (R2 = 0.70, p < 0.00001). We hypothesise that this observation was due to the contribution of N2O from another production process, most probably fungal denitrification. An oxygen isotope fractionation model was used to test various scenarios with different magnitudes of branching isotope effects at different steps in the reduction process. The results suggest that during denitrification the isotope exchange occurs prior to the isotope branching and that the mechanism of this exchange is mostly associated with the enzymatic nitrite reduction mediated by NIR. For bacterial denitrification, the branching isotope effect can be surprisingly low, about (0.0±0.9) ‰; in contrast to fungal denitrification where higher values of up to 30‰ have been reported previously. This suggests that δ18O might be used as a tracer for differentiation between bacte- 5 rial and fungal denitrification, due to their different magnitudes of branching isotope effect
Oxygen isotope fractionation during N2O production by soil denitrification
The isotopic composition of soil-derived N<sub>2</sub>O can help differentiate
between N<sub>2</sub>O production pathways and estimate the fraction of N<sub>2</sub>O
reduced to N<sub>2</sub>. Until now, <i>δ</i><sup>18</sup>O of N<sub>2</sub>O has been rarely
used in the interpretation of N<sub>2</sub>O isotopic signatures because of the
rather complex oxygen isotope fractionations during N<sub>2</sub>O production by
denitrification. The latter process involves nitrate reduction mediated
through the following three enzymes: nitrate reductase (NAR), nitrite
reductase (NIR) and nitric oxide reductase (NOR). Each step removes one
oxygen atom as water (H<sub>2</sub>O), which gives rise to a branching isotope
effect. Moreover, denitrification intermediates may partially or fully
exchange oxygen isotopes with ambient water, which is associated with an
exchange isotope effect. The main objective of this study was to decipher
the mechanism of oxygen isotope fractionation during N<sub>2</sub>O production by
soil denitrification and, in particular, to investigate the relationship
between the extent of oxygen isotope exchange with soil water and the
<i>δ</i><sup>18</sup>O values of the produced N<sub>2</sub>O.
<br><br>
In our soil incubation experiments Δ<sup>17</sup>O isotope tracing was applied
for the first time to simultaneously determine the extent of oxygen isotope
exchange and any associated oxygen isotope effect. We found that N<sub>2</sub>O
formation in static anoxic incubation experiments was typically associated
with oxygen isotope exchange close to 100 % and a stable difference
between the <sup>18</sup>O ∕ <sup>16</sup>O ratio of soil water and the N<sub>2</sub>O
product of
<i>δ</i><sup>18</sup>O(N<sub>2</sub>O ∕ H<sub>2</sub>O) = (17.5 ± 1.2) ‰.
However, flow-through experiments gave lower oxygen isotope exchange down to
56 % and a higher <i>δ</i><sup>18</sup>O(N<sub>2</sub>O ∕ H<sub>2</sub>O) of up to
37 ‰. The extent of isotope exchange and
<i>δ</i><sup>18</sup>O(N<sub>2</sub>O ∕ H<sub>2</sub>O) showed a significant correlation
(<i>R</i><sup>2</sup> = 0.70, <i>p</i> < 0.00001). We hypothesize that this
observation was due to the contribution of N<sub>2</sub>O from another production
process, most probably fungal denitrification.
<br><br>
An oxygen isotope fractionation model was used to test various scenarios with
different magnitudes of branching isotope effects at different steps in the
reduction process. The results suggest that during denitrification, isotope
exchange occurs prior to isotope branching and that this exchange is mostly
associated with the enzymatic nitrite reduction mediated by NIR. For
bacterial denitrification, the branching isotope effect can be surprisingly
low, about (0.0 ± 0.9) ‰, in contrast to fungal
denitrification where higher values of up to 30 ‰ have been reported
previously. This suggests that <i>δ</i><sup>18</sup>O might be used as a tracer for
differentiation between bacterial and fungal denitrification, due to their
different magnitudes of branching isotope effects
Evidence of O2 consumption in underway seawater lines: Implications for air-sea O2 and CO2 fluxes
We observed O2 deficits of 0.5 to 2.0% (1 to 4 mol/kg) in the underway seawater lines of three different ships. Deficits in O2/Ar and isotopic enrichments in dissolved O2 observed in underway seawater lines indicate a respiratory removal process. A 1% respiratory bias in underway lines would lead to a 2.5-5 atm (2.5-5pbar) enhancement in surface water pCO2. If an underway pCO2 bias of this magnitude affectedall measurements, the global oceanic carbon uptake based on pCO 2 climatologies would be 0.5-0.8 Pg/yr higher than the present estimate of 1.6 Pg/yr. Treatment of underway lines with bleach for several hours and thorough flushing appeared to minimize O2 loss. Given the increasing interest in underway seawater measurements for the determination of surface CO2 and O2 fluxes, respiration in underway seawater lines must be identified and eliminated on all observing ships to ensure unbiased data
Learning Aerial Image Segmentation from Online Maps
This study deals with semantic segmentation of high-resolution (aerial)
images where a semantic class label is assigned to each pixel via supervised
classification as a basis for automatic map generation. Recently, deep
convolutional neural networks (CNNs) have shown impressive performance and have
quickly become the de-facto standard for semantic segmentation, with the added
benefit that task-specific feature design is no longer necessary. However, a
major downside of deep learning methods is that they are extremely data-hungry,
thus aggravating the perennial bottleneck of supervised classification, to
obtain enough annotated training data. On the other hand, it has been observed
that they are rather robust against noise in the training labels. This opens up
the intriguing possibility to avoid annotating huge amounts of training data,
and instead train the classifier from existing legacy data or crowd-sourced
maps which can exhibit high levels of noise. The question addressed in this
paper is: can training with large-scale, publicly available labels replace a
substantial part of the manual labeling effort and still achieve sufficient
performance? Such data will inevitably contain a significant portion of errors,
but in return virtually unlimited quantities of it are available in larger
parts of the world. We adapt a state-of-the-art CNN architecture for semantic
segmentation of buildings and roads in aerial images, and compare its
performance when using different training data sets, ranging from manually
labeled, pixel-accurate ground truth of the same city to automatic training
data derived from OpenStreetMap data from distant locations. We report our
results that indicate that satisfying performance can be obtained with
significantly less manual annotation effort, by exploiting noisy large-scale
training data.Comment: Published in IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSIN
Subnanosecond Fluctuations in Low-Barrier Nanomagnets
Fast magnetic fluctuations due to thermal torques have useful technological
functionality ranging from cryptography to probabilistic computing. The
characteristic time of fluctuations in typical uniaxial anisotropy magnets
studied so far is bounded from below by the well-known energy relaxation
mechanism. This time scales as , where parameterizes the
strength of dissipative processes. Here, we theoretically analyze the
fluctuating dynamics in easy-plane and antiferromagnetically coupled
nanomagnets. We find in such magnets, the dynamics are strongly influenced by
fluctuating intrinsic fields, which give rise to an additional dephasing-type
mechanism for washing out correlations. In particular, we establish two time
scales for characterizing fluctuations (i) the average time for a nanomagnet to
reverse|which for the experimentally relevant regime of low damping is governed
primarily by dephasing and becomes independent of , (ii) the time scale
for memory loss of a single nanomagnet|which scales as and is
governed by a combination of energy dissipation and dephasing mechanism. For
typical experimentally accessible values of intrinsic fields, the resultant
thermal-fluctuation rate is increased by multiple orders of magnitude when
compared with the bound set solely by the energy relaxation mechanism in
uniaxial magnets. This could lead to higher operating speeds of emerging
devices exploiting magnetic fluctuations
Environmental Attitudes in 28 European Countries Derived From Atheoretically Compiled Opinions and Self-Reports of Behavior
People differ in their personal commitment to fighting climate change and protecting the environment. The question is, can we validly measure people's commitment by what they say and what they claim they do in opinion polls? In our research, we demonstrate that opinions and reports of past behavior can be aggregated into comparable depictions of people's personal commitment to fighting climate change and protecting the environment (i.e., their environmental attitudes). In contrast to the commonly used operational scaling approaches, we ground our measure of people’s environmental attitudes in a mathematically formalized psychological theory of the response process - the Campbell paradigm. This theory of the response process has already been extensively validated, and its relevance for manifest behavior has repeatedly been shown as well. In our secondary analysis of Eurobarometer data (N = 27,998) from 28 European countries, we apply the Campbell paradigm to a set of indicators that was not originally collected to be aggregated into a single scale. With our research, we propose a distinct way to measure behavior-relevant environmental attitudes that can be used even with a set of indicators that was originally atheoretically compiled. Overall, our study suggests that the Campbell paradigm provides a sound psychological measurement theory that can be applied to cross-cultural comparisons in the environmental protection domain
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