The strong intervening absorption system at redshift 1.15 towards the very bright quasar HE 0515−4414 is the most studied absorber for measuring possible cosmological variations in the fine-structure ...constant,
α
. We observed HE 0515−4414 for 16.1 h with the Very Large Telescope and present here the first constraint on relative variations in
α
with parts-per-million (ppm) precision from the new ESPRESSO spectrograph: Δ
α
/
α
= 1.3 ± 1.3
stat
± 0.4
sys
ppm. The statistical uncertainty (1
σ
) is similar to the ensemble precision of previous large samples of absorbers and derives from the high signal-to-noise ratio achieved (≈105 per 0.4 km s
−1
pixel). ESPRESSO’s design, and the calibration of our observations with its laser frequency comb, effectively removed wavelength calibration errors from our measurement. The high resolving power of our ESPRESSO spectrum (
R
= 145 000) enabled the identification of very narrow components within the absorption profile, allowing a more robust analysis of Δ
α
/
α
. The evidence for the narrow components is corroborated by their correspondence with previously detected molecular hydrogen and neutral carbon. The main remaining systematic errors arise from ambiguities in the absorption profile modelling, effects from redispersing the individual quasar exposures, and convergence of the parameter estimation algorithm. All analyses of the spectrum, including systematic error estimates, were initially blinded to avoid human biases. We make our reduced ESPRESSO spectrum of HE 0515−4414 publicly available for further analysis. Combining our ESPRESSO result with 28 measurements, from other spectrographs, in which wavelength calibration errors have been mitigated yields a weighted mean Δ
α
/
α
= −0.5 ± 0.5
stat
± 0.4
sys
ppm at redshifts 0.6−2.4.
Raman scattering enables unforeseen uses for the laser guide-star system of the Very Large Telescope. Here, we present the observation of one up-link sodium laser beam acquired with the ESPRESSO ...spectrograph at a resolution λ/Δλ∼140 000. In 900 s on source, we detect the pure rotational Raman lines of ^{16}O_{2}, ^{14}N_{2}, and ^{14}N^{15}N (tentatively) up to rotational quantum numbers J of 27, 24, and 9, respectively. We detect the ^{16}O_{2} fine-structure lines induced by the interaction of the electronic spin S and end-over-end rotational angular momentum N in the electronic ground state of this molecule up to N=9. The same spectrum also reveals the ν_{1←0} rotational-vibrational Q-branch for ^{16}O_{2} and ^{14}N_{2}. These observations demonstrate the potential of using laser guide-star systems as accurate calibration sources for characterizing new astronomical spectrographs.
We present here the preliminary design of the RIZ module, one of the visible spectrographs of the ANDES instrument 1. It is a fiber-fed high-resolution, high-stability spectrograph. Its design ...follows the guidelines of successful predecessors such as HARPS and ESPRESSO. In this paper we present the status of the spectrograph at the preliminary design stage. The spectrograph will be a warm, vacuum-operated, thermally controlled and fiber-fed echelle spectrograph. Following the phase A design, the huge etendue of the telescope will be reformed in the instrument with a long slit made of smaller fibers. We discuss the system design of the spectrographs system.
The strong intervening absorption system at redshift 1.15 towards the very bright quasar HE 0515\(-\)4414 is the most studied absorber for measuring possible cosmological variations in the ...fine-structure constant, \(\alpha\). We observed HE 0515\(-\)4414 for 16.1\(\,\)h with the Very Large Telescope and present here the first constraint on relative variations in \(\alpha\) with parts-per-million (ppm) precision from the new ESPRESSO spectrograph: \(\Delta\alpha/\alpha = 1.3 \pm 1.3_{\rm stat} \pm 0.4_{\rm sys}\,{\rm ppm}\). The statistical uncertainty (1\(\sigma\)) is similar to the ensemble precision of previous large samples of absorbers, and derives from the high S/N achieved (\(\approx\)105 per 0.4\(\,\)km\(\,\)s\(^{-1}\) pixel). ESPRESSO's design, and calibration of our observations with its laser frequency comb, effectively removed wavelength calibration errors from our measurement. The high resolving power of our ESPRESSO spectrum (\(R=145000\)) enabled the identification of very narrow components within the absorption profile, allowing a more robust analysis of \(\Delta\alpha/\alpha\). The evidence for the narrow components is corroborated by their correspondence with previously detected molecular hydrogen and neutral carbon. The main remaining systematic errors arise from ambiguities in the absorption profile modelling, effects from redispersing the individual quasar exposures, and convergence of the parameter estimation algorithm. All analyses of the spectrum, including systematic error estimates, were initially blinded to avoid human biases. We make our reduced ESPRESSO spectrum of HE 0515\(-\)4414 publicly available for further analysis. Combining our ESPRESSO result with 28 measurements, from other spectrographs, in which wavelength calibration errors have been mitigated, yields a weighted mean \(\Delta\alpha/\alpha = -0.5 \pm 0.5_{\rm stat} \pm 0.4_{\rm sys}\,\)ppm at redshifts 0.6-2.4.
The
predicts that regulation-related factors in the student and in the context combine to determine the student's levels in emotional variables, stress, and coping strategies. The objective of the ...present research was to test this prediction in the aspect of coping strategies. Our hypothesis posed that students' level of self-regulation (low-medium-high), in combination with the level of regulation promoted in teaching (low-medium-high), would determine the type of strategies students used to cope with academic stress; the interaction of these levels would focus coping strategies either toward emotions or toward the problem. A total of 944 university students completed validated questionnaires on self-regulation, regulatory teaching, and coping strategies, using an online tool. ANOVAs and MANOVAs (3 × 1; 3 × 3; 5 × 1) were carried out, in a quasi-experimental design by selection. Level of self-regulation and level of regulatory teaching both had a significant effect on the type of coping strategies used. The most important finding was that the combined level of self-regulation and external regulation, on a five-level scale or heuristic, predicted the type of coping strategies that were used. In conclusion, the fact that this combination can predict type of coping strategies used by the student lends empirical support to the initial theory. Implications for the teaching-learning process at university and for students' emotional health are discussed.
► Field measurements show that soil erosion in olive orchards eroded nearly 30% of the soil profile over a 250-year time period. ► Models calibrated with historical data on soil management reflect ...the large temporal variation in soil erosion rates. ► Soil erosion rates are above critical thresholds for sustainability, even during historical periods with less intensive management. ► Agronomic practices resulted in continuously increasing yields since 1752.
Olive orchards are an important agro-ecosystem in the Mediterranean. Soil erosion is a widely recognized threat to their sustainability. However, the variability of short-term soil erosion measurements and the limited understanding of driving processes result in a considerable uncertainty over the long-term effects of soil erosion. This study aims at measuring and modelling soil erosion rates in olive orchards over a 250-year period, and relating these to changes in management practices and yield, as documented from historical sources. In three study areas in S-Spain, the height of relic tree mounds was measured in olive orchards dated between 153 and 291 years old to determine soil profile truncation. Measured average soil erosion rates were between 29 and 47
t
ha
−1
year
−1. Historical documents allowed characterizing land management since 1752 in eight distinct periods. This information was then used to calibrate a soil erosion model, combining water and tillage erosion. The model reproduced the temporal patterns in soil erosion rates and showed considerable historical variation: between 8 and 124
t
ha
−1
year
−1 for water and between 3 and 42
t
ha
−1
year
−1 for tillage. Mainly due to improved agronomic practices, yield was not affected by soil erosion and has continuously increased over time.
Mechanization of agriculture drastically increases labour productivity in crop production, playing a major role in industrialization by freeing up workforce for industry and services. These ...historical processes are well studied, but there is much less knowledge on their environmental implications, particularly the carbon footprint.
In this work, we aimed to reconstruct the complete historical process of mechanization in Spanish agriculture at the national scale, estimating the carbon footprint of traction through a life cycle assessment approach. The assessment includes greenhouse gas emissions from working animals and feed production, and accounts for the historical changes in the energy efficiency of the industrial production of machinery and fuels.
The results reveal an increase in the carbon footprint of traction from 3.1 Tg CO2e yr−1 in 1900 to 11–12 Tg CO2e yr−1 in the 1970s and 1980s, decreasing to 7–8 Tg CO2e yr−1 in 2010–2014. Area-based emissions ranged 185–242 kg CO2e ha−1 yr−1 in 1900–1933, when the practical totality of traction was animal, and 503–540 kg CO2e ha−1 yr−1 in the 21st century, when animal traction had almost completely disappeared. Product-based emissions were similar at the beginning and at the end of the study period, as the productivity growth offset the area-based emissions growth. The results show a large peak in emissions during the main decades of the mechanization process. Thus, the large savings observed in the last three decades start from a very high emission level. The carbon footprint of traction could be reduced by mimicking the logic of traditional organic systems but still benefiting from modern technological efficiency, through the self-production of the fuel. Our analysis, however, shows that a simple shift to biofuels may actually increase greenhouse gas emissions and consume a large share of the current agricultural output. Therefore, its combination with significant reductions in fuel and feed demand would be necessary to achieve its mitigation potential.
•Detailed reconstruction of inventory data on animal and mechanical traction.•Animal traction emissions depend on species mix and feed emission factor.•Higher greenhouse gas emissions in mechanized systems.•Highest emissions during the transition from animal to mechanical traction.•Self-produced biofuels could contribute to mitigation but also increase emissions.
The main type of consumptive water use is crop evapotranspiration. The historical evolution of crop evapotranspiration depends on climate and cropland changes. These two latter variables present ...complex interactions and are expected to continue changing in the future, but the coupling between these two processes is insufficiently addressed in the literature. The objective of this study is to disentangle the impact of historical climate and cropland changes on four water performance indicators of agroecosystems in a Mediterranean country (Spain) between 1922 and 2016: crop water requirements actual evapotranspiration, the net primary productivity-based water intensity and violet water, accounting for water stress. These indicators were estimated based on soil water balances and the effects of climate and cropland were unravelled through counterfactual scenarios. The results showed that climate change tended to increase actual evapotranspiration (9%), crop water requirements (14%) and net primary productivity-based water intensity (8%), its greatest impact being on violet water (increasing it by 34%). The cropland variable produced effects of different positive or negative signs according to the parameters considered (type of crop, crop management and point in space-time). In aggregate terms, however, the cropland effect pushed in the same direction as climate change, causing increases in actual evapotranspiration (11%), violet water (15%) and crop water requirements (3%), while reducing net primary productivity-based water intensity (−15%). This approach allows us to quantify and show the importance of agricultural industrialization on the water performance of agroecosystems. In this way, our results highlight great opportunities to manoeuvre to adapt agriculture to climate change through agronomic management and hydrological planning options. Complex interaction patterns between climate and cropland effects were shown. Moreover, geographical, crop-type and temporal evapotranspiration hotspots and drivers were uncovered, and interrelations among the water performance indicators were discussed, thus raising relevant points of discussion in the field.
Display omitted
•Cropland and climate effects on agroecosystems water performance were separated.•Overall cropland changes tend to exacerbate the climate effects.•Contrarily to irrigated, rainfed cropland changes tend to reduce climate effects.•Complex interaction patterns between climate and cropland evolution were revealed.•Great opportunities to adapt cropland to climate change through improving management.
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