671 research outputs found
Relative Importance of Nitric Oxide Physical Drivers in the Lower Thermosphere
Nitric oxide (NO) observations from the Solar Occultation for Ice Experiment and Student Nitric Oxide Explorer satellite instruments are investigated to determine the relative importance of drivers of short‐term NO variability. We study the variations of deseasonalized NO anomalies by removing a climatology, which explains between approximately 70% and 90% of the total NO budget, and relate them to variability in geomagnetic activity and solar radiation. Throughout the lower thermosphere geomagnetic activity is the dominant process at high latitudes, while in the equatorial region solar radiation is the primary source of short‐term NO changes. Consistent results are obtained on estimated geomagnetic and radiation contributions of NO variations in the two data sets, which are nearly a decade apart in time. The analysis presented here can be applied to model simulations of NO to investigate the accuracy of the parametrized physical drivers
Effects of elevational range shift on the morphology and physiology of a carabid beetle invading the sub-Antarctic Kerguelen Islands.
Climatic changes can induce geographic expansion and altitudinal shifts in the distribution of invasive species by offering more thermally suitable habitats. At the remote sub-Antarctic Kerguelen Islands, the predatory insect Merizodus soledadinus (Coleoptera: Carabidae), introduced in 1913, rapidly invaded coastal habitats. More recent colonisation of higher elevation habitats by this species could be underlain by their increased thermal suitability as the area has warmed. This study compared the effect of elevational range shift on the morphology and physiology of adult M. soledadinus sampled along two altitudinal transects (from the foreshore to 250 m a.s.l.) and a horizontal lowland transect orthogonal to the seashore (400 m length). Although high inter-individual and inter-transect variations in the traits examined were present, we observed that body mass of males and females tended to decrease with elevation, and that triglyceride contents decreased with distance from the shore. Moreover, protein contents of females as well as those of 26 metabolites were influenced significantly by distance to the foreshore. These results suggest that future climate change at the Kerguelen Islands will further assist the colonisation of lowland inland and higher altitude habitats by this aggressively invasive predator, by making previously sub-optimal habitats progressively more suitable
Optimum sterilization: a comparative study between average and surface quality
Sterilization temperatures to maximize volume average or surface quality retention were calculated for one-dimensional conduction heating foods as a function of (1) Food Properties, (2) Processing Conditions and (3) Processing Criteria. A target lethality at the least-lethality point was used as a constraint, and optimal temperatures were qualitatively and quantitatively compared for equal design variables.
Average quality optimum conditions depend linearly on the inverse square of the Drefq-value for the quality factor. These conditions do not vary linearly with all the other influential variables, opposite to what had been observed for surface quality. Optimum temperature for maximum average quality is always higher than the corresponding one for surface quality, but the difference is not constant. A systematic approach to the dependence of average quality optimal conditions on all the relevant parameters was carried out and quantitative relations were obtained. Optimum average quality retention is independent of surface heat transfer resistance
On the lack of robustness of hydrologic models regarding water balance simulation: a diagnostic approach applied to three models of increasing complexity on 20 mountainous catchments
This paper investigates the robustness of rainfall–runoff models when their
parameters are transferred in time. More specifically, we propose an approach
to diagnose their ability to simulate water balance on periods with different hydroclimatic
characteristics. The testing procedure consists in a series of parameter
calibrations over 10 yr periods and the systematic analysis of mean flow volume
errors on long records. This procedure was applied to three conceptual models
of increasing structural complexity over 20 mountainous catchments in southern France.
The results showed that robustness problems are common. Errors on 10 yr mean
flow volume were significant for all calibration periods and model structures.
Various graphical and numerical tools were used to investigate these errors and
unexpectedly strong similarities were found in the temporal evolutions
of these volume errors. We indeed showed that relative changes in simulated
mean flow between 10 yr periods can remain similar, regardless of the calibration
period or the conceptual model used. Surprisingly, using longer records for parameters
optimisation or using a semi-distributed 19-parameter daily model instead of a simple
1-parameter annual formula did not provide significant improvements regarding these
simulation errors on flow volumes. While the actual causes for these robustness problems
can be manifold and are difficult to identify in each case, this work highlights that the
transferability of water balance adjustments made during calibration can be poor,
with potentially huge impacts in the case of studies in non-stationary conditions
Impact of interface traps on charge noise, mobility and percolation density in Ge/SiGe heterostructures
Hole spins in Ge/SiGe heterostructure quantum dots have emerged as promising
qubits for quantum computation. The strong spin-orbit coupling (SOC),
characteristic of heavy-hole states in Ge, enables fast and all-electrical
qubit control. However, SOC also increases the susceptibility of spin qubits to
charge noise. While qubit coherence can be significantly improved by operating
at sweet spots with reduced hyperfine or charge noise sensitivity, the latter
ultimately limits coherence, underlining the importance of understanding and
reducing charge noise at its source. In this work, we study the voltage-induced
hysteresis commonly observed in SiGe-based quantum devices and show that the
dominant charge fluctuators are localized at the semiconductor-oxide interface.
By applying increasingly negative gate voltages to Hall bar and quantum dot
devices, we investigate how the hysteretic filling of interface traps impacts
transport metrics and charge noise. We find that the gate-induced accumulation
and trapping of charge at the SiGe-oxide interface leads to an increased
electrostatic disorder, as probed by transport measurements, as well as the
activation of low-frequency relaxation dynamics, resulting in slow drifts and
increased charge noise levels. Our results highlight the importance of a
conservative device tuning strategy and reveal the critical role of the
semiconductor-oxide interface in SiGe heterostructures for spin qubit
applications
Identifying factors associated with sedentary time after stroke. Secondary analysis of pooled data from nine primary studies.
<p><b>Background</b>: High levels of sedentary time increases the risk of cardiovascular disease, including recurrent stroke.</p> <p><b>Objective</b>: This study aimed to identify factors associated with high sedentary time in community-dwelling people with stroke.</p> <p><b>Methods</b>: For this data pooling study, authors of published and ongoing trials that collected sedentary time data, using the activPAL monitor, in community-dwelling people with stroke were invited to contribute their raw data. The data was reprocessed, algorithms were created to identify sleep-wake time and determine the percentage of waking hours spent sedentary. We explored demographic and stroke-related factors associated with total sedentary time and time in uninterrupted sedentary bouts using unique, both univariable and multivariable, regression analyses.</p> <p><b>Results</b>: The 274 included participants were from Australia, Canada, and the United Kingdom, and spent, on average, 69% (SD 12.4) of their waking hours sedentary. Of the demographic and stroke-related factors, slower walking speeds were significantly and independently associated with a higher percentage of waking hours spent sedentary (p = 0.001) and uninterrupted sedentary bouts of <i>>30</i> and <i>>60 min</i> (p = 0.001 and p = 0.004, respectively). Regression models explained 11–19% of the variance in total sedentary time and time in prolonged sedentary bouts.</p> <p><b>Conclusion</b>: We found that variability in sedentary time of people with stroke was largely unaccounted for by demographic and stroke-related variables. Behavioral and environmental factors are likely to play an important role in sedentary behavior after stroke. Further work is required to develop and test effective interventions to address sedentary behavior after stroke.</p
The IDA-80 measurement evaluation programme on mass spectrometric isotope dilution analysis of uranium and plutonium. Vol.II: Preparation, characterization and transport of test samples
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