Faramarzi M.,Eawag - Swiss Federal Institute of Aquatic Science and Technology |
Faramarzi M.,Isfahan University of Technology |
Yang H.,Eawag - Swiss Federal Institute of Aquatic Science and Technology |
Schulin R.,Universitatstr 16 |
Abbaspour K.C.,Eawag - Swiss Federal Institute of Aquatic Science and Technology
Agricultural Water Management | Year: 2010
In most parts of Iran, water scarcity has been intensifying and posing a threat to the sustainability of agricultural production. Wheat is the dominant crop and the largest irrigation water user in Iran; hence, understanding of the crop yield-water relations in wheat across the country is essential for a sustainable production. Based on a previously calibrated hydrologic model, we modeled irrigated and rainfed wheat yield (Y) and consumptive water use (ET) with uncertainty analysis at a subbasin level in Iran. Simulated Y and ET were used to calculate crop water productivity (CWP). The model was then used to analyze the impact of several stated policies to improve the agricultural system in Iran. These included: increasing the quantity of cereal production through more efficient use of land and water resources, improving activities related to soil moisture conservation and retention, and optimizing fertilizer application. Our analysis of the ratio of water use to internal renewable water resources revealed that 23 out of 30 provinces were using more than 40% of their water resources for agriculture. Twelve provinces reached a ratio of 100% and even greater, indicating severe water scarcity and groundwater resource depletion. An analysis of Y-CWP relationship showed that one unit increase in rainfed wheat yield resulted in a lesser additional water requirement than irrigated wheat, leading to a larger improvement in CWP. The inference is that a better water management in rainfed wheat, where yield is currently small, will lead to a larger marginal return in the consumed water. An assessment of improvement in soil available water capacity (AWC) showed that 18 out of 30 provinces are more certain to save water while increasing AWC through proper soil management practices. As wheat self-sufficiency is a desired national objective, we estimated the water requirement of the year 2020 (keeping all factors except population constant) to fulfill the wheat demand. The results showed that 88% of the additional wheat production would need to be produced in the water scarce provinces. Therefore, a strategic planning in the national agricultural production and food trade to ensure sustainable water use is needed. This study lays the basis for a systematic analysis of the potentials for improving regional and national water use efficiency. The methodology used in this research, could be applied to other water scarce countries for policy impact analysis and the adoption of a sustainable agricultural strategy. © 2010 Elsevier B.V.
Steiner F.M.,University of Innsbruck |
Pautasso M.,Universitatstr 16 |
Pautasso M.,Animal and Plant Health Unit |
Zettel H.,Natural History Museum Vienna |
And 3 more authors.
Systematic Biology | Year: 2015
Current science evaluation still relies on citation performance, despite criticisms of purely bibliometric research assessments. Biological taxonomy suffers from a drain of knowledge and manpower, with poor citation performance commonly held as one reason for this impediment. But is there really such a citation impediment in taxonomy?We compared the citation numbers of 306 taxonomic and 2291 non-taxonomic research articles (2009-2012) onmosses, orchids, ciliates, ants, and snakes, usingWeb of Science (WoS) and correcting for journal visibility. For three of the five taxa, significant differences were absent in citation numbers between taxonomic and non-taxonomic papers. This was also true for all taxa combined, although taxonomic papers received more citations than non-taxonomic ones. Our results show that, contrary to common belief, taxonomic contributions do not generally reduce a journal's citation performance and might even increase it. The scope of many journals rarely featuring taxonomy would allow editors to encourage a larger number of taxonomic submissions. Moreover, between 1993 and 2012, taxonomic publications accumulated faster than those from all biological fields. However, less than half of the taxonomic studies were published in journals in WoS. Thus, editors of highly visible journals inviting taxonomic contributions could benefit from taxonomy's strong momentum. The taxonomic output could increase even more than at its current growth rate if: (i) taxonomists currently publishing on other topics returned to taxonomy and (ii) nontaxonomists identifying the need for taxonomic acts started publishing these, possibly in collaboration with taxonomists. Finally, considering the high number of taxonomic papers attracted by the journal Zootaxa, we expect that the taxonomic community would indeed use increased chances of publishing in WoS indexed journals. We conclude that taxonomy's standing in the present citation-focused scientific landscape could easily improve-if the community becomes aware that there is no citation impediment in taxonomy. © The Author(s) 2015.
Martins J.Z.R.,Universitatstr 16 |
Chappey C.,Genentech |
Haddad M.,Monogram Biosciences |
Whitcomb J.M.,Monogram Biosciences |
And 3 more authors.
Epidemics | Year: 2010
To detect general patterns and temporal trends of HIV-1 resistance, we apply principal component analysis (PCA) to in vitro fitness data. Twenty-eight thousand virus samples, obtained between 2002 and 2008, were assayed for fitness in 16 to 21 selective environments. Fitness measurements are based on replication capacity (RC), which quantifies in vitro viral replication in a single cycle of infection. RC is determined both in the absence of drugs and in the presence of 6-7 nucleoside analog reverse transcriptase inhibitors (NRTIs), 3-4 non-nucleoside reverse transcriptase inhibitors (NNRTIs), and 6-9 protease inhibitors (PIs). PCA shows remarkable structure in RC across the different environments, which reveals differences in the patterns of resistance and cross-resistance between drugs or between drug classes. To probe the causes of the observed patterns, we develop a model to generate simulated data and subject these simulated data to an equivalent analysis. By comparing the outcomes of PCA on the original and the simulated data, we quantify which part of the total variance of the original data is due to non-specific effects, class-specific effects, and drug-specific effects of resistance mutations. We find that relative fitness is mainly drug-independent and that drug-specific effects are substantially bigger than class-specific effects for NRTIs, but not for NNRTIs or PIs. The observed patterns remain remarkably stable over the period of observation. Comparison with known potent combination therapies suggests that PCA helps to identify combinations that act synergistically in preventing the emergence of resistance. © 2010 Elsevier B.V. All rights reserved.
Bahlmann E.,University of Hamburg |
Bernasconi S.M.,Universitatstr 16 |
Bouillon S.,Vrije Universiteit Brussel |
Houtekamer M.,Netherlands Institute of Ecology |
And 9 more authors.
Organic Geochemistry | Year: 2010
Nitrogen isotopes of organic matter are increasingly studied in marine biogeochemistry and geology, plant and animal ecology, and paleoceanography. Here, we present results of an inter-laboratory test on determination of nitrogen isotope ratios in marine and lacustrine sediments. Six different samples covering a wide range of total nitrogen content and δ15N values were analyzed by eight different laboratories using their routine procedures. The laboratories were asked to measure three batches with three replicates for each sample to assess accuracy and variability within and among laboratories; this permits assessment of repeatability and reproducibility, which are essential in meta analysis of the increasing database on δ15N values in marine sediments. The grand average δ15N values for individual samples ranged from 1.65-10.90‰. One laboratory exhibited an average bias of -0.27‰ compared to the mean of all other laboratories. Apart from one sample, which showed an exceptionally high overall standard deviation (OSD) of 0.51‰, the analytical precision (1 s) averaged 0.24‰, ranging from 0.18-0.31‰ for individual samples. Out of the eight participating laboratories, two showed a significantly elevated within-laboratory standard deviation (WLSD) of 0.41‰ and 0.32‰ compared to an average WLSD of 0.15‰ for the other laboratories. The WLSD was inversely correlated with the ratio of peak height to peak width, which was taken as a simple measure of peak shape. Moreover, our data also revealed an inverse correlation between total nitrogen content and measurement precision. These correlations may provide guidance for improving the measurement precision of individual laboratories. Based on the results of this round robin test, we have estimated the expanded measurement uncertainty on the 2σ level to 0.45‰ for sediment samples with a nitrogen content >0.07 wt%. Sediment samples with lower nitrogen contents cannot be measured with sufficient precision without additional precautions and care should be taken when interpreting δ15N signatures and records for sediments with nitrogen concentrations <0.07 wt%. © 2009 Elsevier Ltd. All rights reserved.
Yeganeh M.,Isfahan University of Technology |
Afyuni M.,Isfahan University of Technology |
Khoshgoftarmanesh A.H.,Isfahan University of Technology |
Rezaeinejad Y.,Isfahan University of Technology |
Schulin R.,Universitatstr 16
Soil Use and Management | Year: 2010
The application of sewage sludge on farmland is practised in many countries since sludge is rich in macro- and micro- nutrients. However, increasing use of sewage sludge on farmland has raised concerns about the potential transport of heavy metals into food chains and groundwater. This study determined for a calcareous soil the effects of sludge application on soil physical properties and transport of zinc (Zn), copper (Cu), and lead (Pb). Secondary anaerobic digested sewage sludge was applied at rates of 0, 25, 50, and 100 t/ha (on a dried weight basis) for four consecutive years and mixed in the top 20-cm of soil. Corn (Zea mays L.) was planted as a spring crop, followed by wheat (Triticum aestivum) as a winter crop. Sludge application increased the dissolved organic matter content and modified the soil structure, increased the soil infiltration rate, saturated hydraulic conductivity, and aggregate stability, and decreased the bulk density. Sludge application greatly increased DTPA (diethylenetriamine pentaacetic acid)-extractable soil metal concentrations to 50 cm depth and significantly to 1 m. In the plots that received four application of 100 t/ha sewage sludge, the mean concentrations of Zn, Cu, and Pb in subsoil increased by 1600, 7, and 4.5 times, respectively, compared with the control. The results indicate that a combination of enhanced soil physical properties, heavy and inefficient irrigation and high organic matter content with heavy metals cause significant metal mobility. High sludge applications pose risks of groundwater and food chain contamination and rates are best restricted to those reflecting the nutrient demand of crops (20 t/ha every 4 to 5 yr or an average of 4 to 5 t/ha/yr). © 2010 The Authors. Journal compilation © 2010 British Society of Soil Science.
Eugster O.,Universitatstr 16 |
Gruber N.,Universitatstr 16
Global Biogeochemical Cycles | Year: 2012
We determine the global rates of marine N-fixation and denitrification and their associated uncertainties by combining marine geochemical and physical data with a new two-dimensional box model that separates the Atlantic from the IndoPacific basins. The uncertainties are estimated using a probabilistic approach on the basis of a suite of 2500 circulation configurations of this box model. N-fixation and denitrification are diagnosed in an inverse manner for each of these configurations using N, P, and the stable nitrogen isotope composition of nitrate as data constraints. Our approach yields a median water column denitrification rate of 52 TgN yr-1 (39 to 66 TgN yr -1, 5th to 95th percentile) and a median benthic denitrification rate of 93 TgN yr-1 (68 to 122 TgN yr-1). The resulting benthic-to-water column denitrification ratio of 1.8 confirms that the isotopic signature of water column denitrification has a limited influence on the global mean stable isotopic value of nitrate due to the dilution of the waters with a denitrification signal with the remainder of the ocean's nitrate pool. On the basis of two different approaches, we diagnose a global N-fixation rate of between 94 TgN yr-1 and 175 TgN yr-1, with a best estimate of 131 TgN yr-1 and 134 TgN yr-1, respectively. Most of the N-fixation occurs in the IndoPacific suggesting a relative close spatial coupling between sources and sinks in the ocean. Our N-fixation and denitrification estimates plus updated estimates of atmospheric deposition and riverine input yield a pre-industrial marine N cycle that is balanced to within 3 TgN yr-1 (-38 to 40 TgN yr-1). Our budget implies a median residence time for fixed N of 4,200yr (3,500 to 5,000yr). © 2012. American Geophysical Union. All Rights Reserved.