•Water entitlements are defined in terms of withdrawal instead of consumption rights.•Water markets reallocate consumption and return flows, impairing downstream uses.•We use a hydro-economic model ...to assess tradeoffs between trading and return flows.•The model is applied to an inter-basin water market in SE Spain.•Return flow-neutral markets reduce profit by EUR 1.6 per m3 of conserved streamflow.
Water markets are water management instruments that can support water reallocation from low to high value agricultural uses. However, unless explicit consideration is given to water uses not directly involved in the trading (e.g. environment), water markets may fail to promote sustainable growth. In inter-basin water markets, the reallocation of water withdrawal entitlements from the selling basin typically involves the reallocation of return flows (the surface and subsurface water that leaves the agricultural system following withdrawal of irrigation water) along with consumptive uses, which may impair environmental flows and affect water uses downstream in the selling basin. This paper couples, using a sequential modular approach, a Positive Multi-Attribute Utility Programming (PMAUP) tool that models the behavior of irrigators and the Soil and Water Assessment Tool (SWAT) eco-hydrologic model to: i) assess the economic and water reallocation potential of a return flow-neutral inter-basin water market; and ii) explore the trading-return flow tradeoffs that stem from relaxing the neutrality principle. Methods are applied to the case of agricultural water markets in the Tagus-Segura interconnected basins in Spain. Results show that enforcing a return flow-neutral water market can reduce returns from trade by up to EUR 1.63 per m3 of conserved streamflow.
The hypothesis of a rebound effect as a consequence of water saving investments is taken analogically from the Jevons paradox models in energy economics. The European Commission (EC) alert about the ...consequences in water stressed regions that are investing heavily in modernization of irrigation networks and systems. This paper reviews the literature, linking water savings with water diversion and water depletion, both from theoretical models and empirical evidence from the published research. In order to increase knowledge of this phenomenon, a new empirical case study is presented based on a survey of 36,000 ha of recently modernized irrigated areas in the Guadalquivir basin (southern Spain). The results of the case study illustrates the conditions that may avoid rebound effect, although the results of the available empirical evidence and the published theoretical research are diverse and lead to contradictory results. Further research is therefore needed to determine the causes and solutions of water saving investment impacts and the possible speculative rebound effect.
This paper explores the impacts of water pricing as a demand management policy, at a regional level (or basin-sector). To this aim, a hydro-economic model for the Guadalquivir River basin (southern ...Spain) is proposed here. This basin constitutes a perfect example of a Mediterranean basin subject to frequent and long drought periods, where challenges related to water scarcity are increasing, leading to social conflicts among water users. Moreover, this basin is characterised by a closure state meaning that all available water resources are already allocated among users. In this context, water pricing policy may act as an effective tool to reduce water demand by encouraging changes of behaviour in water users. In particular, those who perform irrigation practices in the agricultural sector. This paper focuses on the irrigation sector since it is the main water user in the basin (87%). Additionally, alternative water-availability scenarios have been used to test the effect of water pricing under drought conditions. The hydro-economic model presented here has been sectorized into four basin sectors with common characteristics (hydro and economic). This enables the analysis of alternative price scenarios in the agricultural sector, in terms of water used, crop patterns and gross margin. Results show that water pricing policy should consider the regional characteristics at the basin-sector scale to gain effectiveness and equity at the river basin scale. Moreover, it has been found that both water availability and the crop pattern at the basin-sector scale have an effect on the reduction of water used (and therefore in gross margin.
Renewable energy sources are believed to reduce drastically greenhouse gas emissions that would otherwise be generated from fossil fuels used to generate electricity. This implies that a unit of ...renewable energy will replace a unit of fossil-fuel, with its CO2 emissions, on an equivalent basis – with no other effects on the grid. But, the fuel economy and emissions in the existing power systems are not proportional with the electricity production of intermittent sources due to cycling of the fossil-fuel plants that make up the balance of the grid (i.e. changing the power output makes thermal units to operate less efficiently).
This study focuses in the interactions between wind generation and thermal plants cycling, by establishing the levels of extra fuel use caused by decreased efficiencies of fossil back-up for wind electricity in Spain. We analyze the production of all thermal plants in 2011, studying scenarios where wind penetration causes major deviations in programming and we define a procedure for quantifying CO2 reductions using emission factors and efficiency curves from existing installations; the objective is to discuss the real contribution of renewable energy to the environmental targets: the results show that CO2 reductions are still relevant at high wind penetration, whilst we also suggest alternatives to improve reliability of the power system.
► Comprehensive analysis of interactions of wind and fuel utilities in the power system. ► Fuel economy is not proportional with wind generation due to cycling of fossil plants. ► The results show that CO2 reductions are still relevant even at high wind penetration. ► Alternatives to improve reliability of future power systems are also pointed out.
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•Commercial polymeric supports coated with TiO2 exhibit photocatalytic activity.•Sol–gel synthesis method is valid for anatase-TiO2 coating at low temperature.•SiO2–TiO2 combination ...with the help of surfactants improves TiO2 adhesion on PMMA.•PMMA is postulated the best polymer as transparent support in the UV–Vis region.
Commercially available transparent polymers are evaluated as support for photoactive TiO2 and tested for their application in gas phase photocatalytic oxidation processes. The polymers were selected on the basis of their optical properties and the TiO2 film adhesion. Two low-temperature surfactant-mediated sol–gel synthesis methods of TiO2–SiO2 nanocomposites are investigated to provide acid TiO2–basic SiO2 interactions for the formation of photocatalytic films of higher quality. These procedures are expected to improve photocatalytic properties compared to those obtained by direct coating of TiO2 on the polymers. One method consists in modifying the polymer surface with a layer of poly(diallyldimethylammonium) chloride, which provides a positively charged surface for the fixation of the alkaline SiO2 sol. The other method is based on reducing the surface tension of the SiO2 sol using perfluorobutane sulfonates. Both methods are compared to direct deposition in terms of homogeneity of the layers and photocatalytic activity for trichloroethylene oxidation. Among the commercial polymers employed poly(methyl methacrylate) processed by sheet moulding showed the best optical properties, TiO2 adhesion, and photocatalytic activity, which was promoted by the deposition of the silica interlayer by both preparation methods.
Abstract
Mounting evidence suggests that science and engineering fields suffer from gender biases. In this paper, we study the physics community, a discipline where women are still under-represented ...and gender disparities persist. To reveal such inequalities, we perform a paper matching analysis using a robust statistical similarity metric. Our analyses indicate that women’s papers tend to have lower visibility in the global citation network, a phenomenon significantly influenced by the temporal aspects of scientific production. Within pairs of similar papers, the authors that publish first tend to obtain more citations. From the group perspective, men have cumulative historical advantages due to women joining the field later and at a slower rate. Altogether, these results indicate that the first-mover advantage plays a crucial role in the emergence of gender disparities in citations of women-authored papers in the physics community.
Abstract
In non-rheumatic atrial fibrillation (AF), left atrial appendage (LAA) is thought to be the source of embolism in 90% of the strokes. Thus, as recent clinical trials have shown the ...non-inferiority of percutaneous LAA closure (LAAc) in comparison to medical treatment, and despite a IIb recommendation in the latest guidelines for concomitant surgical LAAc, we sought to investigate the beneficial effect of LAAc in the surgical population. A meta-analysis model was performed comparing studies including any cardiac surgery with or without concomitant surgical LAAc reporting stoke/embolic events and/or mortality, from inception to January 2019. Twenty-two studies (280 585 patients) were included in the model. Stroke/embolic events both in the perioperative period relative risk (RR) 0.66, 95% confidence interval (CI) 0.53–0.82; P = 0.0001 and during follow-up of >2 years (RR 0.67, 95% CI 0.51–0.89; P < 0.005) were significantly reduced in patients who underwent surgical LAAc (RR 0.71, 95% CI 0.58–0.87; P = 0.001). Regarding the rate of preoperative AF, LAAc showed protective effect against stroke/embolic events in studies with >70% preoperative AF (RR 0.64, 95% CI 0.53–0.77; P < 0.00001) but no benefit in the studies with <30% of preoperative AF (RR 0.77, 95% CI 0.46–1.28; P = 0.31). Postoperative mortality was also significantly lower in surgical patients with LAAc at the mid- and long-term follow-up. (RR 0.72, 95% CI 0.67–0.78; P < 0.00001; I2 = 0%). Based on these findings, concomitant surgical LAAc is associated with lower rates of embolic events and stroke in the postoperative period in patients with preoperative AF and also improves postoperative mortality in the mid- and long-term follow-up.
Antibiotics are added to semen extenders when preparing commercial semen doses for artificial insemination according to national and international guidelines. However, this addition of antibiotics ...represents non-therapeutic usage and could be contributing to the development of antibiotic resistance. Colloid centrifugation was shown to reduce the load of bacteria present in boar semen and was capable of removing all bacteria if performed directly after semen collection, albeit with some loss of spermatozoa. The present experiment was conducted with a low density colloid to investigate whether it was possible to separate all of the spermatozoa from seminal plasma i.e. without selection for robust spermatozoa, or whether this would have a detrimental effect on sperm quality. Ejaculates from nine boars were extended in Beltsville Thawing Solution without antibiotics and were transported to the laboratory for Single Layer Centrifugation (SLC) on modified Porcicoll i.e. at a low density (S). A further modification was that a sterile inner tube was included inside some of the 50 mL centrifuge tubes to facilitate harvesting of the sperm pellet (M). Aliquots of all samples (control, S and M) were cultured for bacterial quantification and identification using standard microbiological methods. Sperm quality was evaluated daily. Three of the C and M samples and five of the S samples did not contain any bacteria. Mean bacterial counts for the remaining samples (colony forming units/mL) were as follows: C 259 ± 216; S 30 ± 22; M 33 ± 15 (P < 0.01). Citrobacter spp., Staphylococcus simulans, Klebsiella variicola, Escherichia coli, Myroides odoratimimus, Proteus spp. and Enterococcus faecalis were identified in the control samples. There were marginal differences in sperm quality among treatments, with sperm velocity and linearity being higher in S and M samples than in C at all time points. However, sperm viability, capacitation and acrosome status were marginally better in controls than in S or M on day 0, but these differences disappeared during storage. Conclusions: centrifugation through a low density colloid can remove or reduce bacterial contamination in boar ejaculates without using antibiotics. Furthermore, it is possible to collect boar ejaculates without bacterial contamination by paying strict attention to hygiene.
•Boar semen was centrifuged on a low density colloid to separate the spermatozoa from seminal plasma.•Controls and resuspended sperm pellets were evaluated for sperm quality.•Aliquots were taken for microbiology and identification by MaldiTof.•Colloid centrifugation removed all or most of the bacteria from the sample.•Sperm quality was not different among treatments.
Books throughout the Middle Ages were written on vellum, the prepared skins of animals, and it has been proposed that medieval readers navigated manuscripts in part by touch, by perceiving and ...recognizing the different textures of pages. However, scholars today often read these same books in printed or digital form, likely having a very different experience from that had with the physical pages. Here, we attempted to understand this difference by quantifying the tactile experience of interacting with vellum as sliding friction. Friction was measured on 14 vellum samples from different animal sources and preparation methods on the hair and flesh sides of the page. Results were correlated to the sensory perception of an untrained panel and explained in terms of statistical surface roughness parameters. Data demonstrate divergence between optical and tactile perception of surface features and physical measurements, calling into question statements about vellum type and quality based on digital images alone. The results are a first step toward understanding the tactile experience of interacting with medieval vellum such that the experience might be approximated by scholars today.
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