183 research outputs found

    Simulating Nitrate-Nitrogen Concentration from a Subsurface Drainage System in Response to Nitrogen Application Rates Using RZWQM2

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    Computer models have been widely used to evaluate the impact of agronomic management on nitrogen (N) dynamics in subsurface drained fields. However, they have not been evaluated as to their ability to capture the variability of nitrate-nitrogen (NO3–N) concentration in subsurface drainage at a wide range of N application rates due to possible errors in the simulation of other system components. The objective of this study was to evaluate the performance of Root Zone Water Quality Model2 (RZWQM2) in simulating the response of NO3–N concentration in subsurface drainage to N application rate. A 16-yr field study conducted in Iowa at nine N rates (0–252 kg N ha−1) from 1989 to 2004 was used to evaluate the model, based on a previous calibration with data from 2005 to 2009 at this site. The results showed that the RZWQM2 model performed “satisfactorily” in simulating the response of NO3–N concentration in subsurface drainage to N fertilizer rate with 0.76, 0.49, and −3% for the Nash-Sutcliffe efficiency, the ratio of the root mean square error to the standard deviation, and percent bias, respectively. The simulation also identified that the N application rate required to achieve the maximum contaminant level for the annual average NO3–N concentration was similar to field-observed data. This study supports the use of RZWQM2 to predict NO3–N concentration in subsurface drainage at various N application rates once it is calibrated for the local condition

    Isolation and characterization of an Aux/IAA gene (LaIAA2) from Larix

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    The phytohormone auxin controls many aspects of plant development. Auxin/indole-3-acetic acid (Aux/IAA)  transcriptional factors are key regulators of auxin responses in plants. To investigate the effects of auxin on  gene expression during the rooting process of Larix cuttings, a subtractive cDNA library was constructed and  272 UniEST were obtained by using suppression subtractive hybridization (SSH). Based on a fragment of 272  UniEST, the full-length cDNA of LaIAA2, an Aux /IAA gene from Larix was isolated. Then, the response  expression of LaIAA2 to auxin was determined by treating with different sources and concentration of auxin and cycloheximide and the expression patterns of LaIAA2 were examined in different tissues. The results show  that LaIAA2 appears to be the first response gene of auxin and LaIAA2 gene was involved in the root  development and auxin signaling. The express pattern of LaIAA2 gene indicated that it might play a central role in root development, specially regulated lateral and adventitious root production.Key words: Aux/IAA gene family, auxin, LaIAA2, Lari

    Matching-based Hybrid Service Trading for Task Assignment over Dynamic Mobile Crowdsensing Networks

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    By opportunistically engaging mobile users (workers), mobile crowdsensing (MCS) networks have emerged as important approach to facilitate sharing of sensed/gathered data of heterogeneous mobile devices. To assign tasks among workers and ensure low overheads, a series of stable matching mechanisms is introduced in this paper, which are integrated into a novel hybrid service trading paradigm consisting of futures trading mode and spot trading mode to ensure seamless MCS service provisioning. In the futures trading mode, we determine a set of long-term workers for each task through an overbooking-enabled in-advance many-to-many matching (OIA3M) mechanism, while characterizing the associated risks under statistical analysis. In the spot trading mode, we investigate the impact of fluctuations in long-term workers' resources on the violation of service quality requirements of tasks, and formalize a spot trading mode for tasks with violated service quality requirements under practical budget constraints, where the task-worker mapping is carried out via onsite many-to-many matching (O3M) and onsite many-to-one matching (OMOM). We theoretically show that our proposed matching mechanisms satisfy stability, individual rationality, fairness and computational efficiency. Comprehensive evaluations also verify the satisfaction of these properties under practical network settings, while revealing commendable performance on running time, participators' interactions, and service quality

    Simulating Dryland Water Availability and Spring Wheat Production in the Northern Great Plains

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    Agricultural system models are useful tools to synthesize field experimental data and to extrapolate results to longer periods of weather and to other cropping systems. The objectives of this study were: (i) to quantify the effects of crop management practices and tillage on soil water and spring wheat (Triticum aestivum L.) production in a continuous spring wheat system using the RZWQM2 model (coupled with CERES-Wheat) under a dryland condition, and (ii) to extend the RZWQM2 model results to longer term weather conditions and propose alternate cropping systems and management practices. Measured soil water content, yield, and total aboveground biomass under different tillage and plant management practices were used to calibrate and evaluate the RZWQM2 model. The model showed no impacts of tillage but late planting greatly reduced grain yield and biomass, in agreement with observed differences among treatments. The hydrologic analysis under long-term climate variability showed a large water deficit (32.3 cm) for spring wheat. Fallowing the cropland every other year conserved 4.2 cm of water for the following wheat year, of which only 1.7 cm water was taken up by wheat, resulting in a yield increase of 249 kg ha−1 (13.7%); however, the annualized mean yield decreased 782 kg ha−1(43.1%) due to 1 yr of fallow. Other long-term simulations showed that optimal planting dates ranged from 1 March to 10 April and the seeding rates with optimum economic return were 3.71 and 3.95 × 106 seeds ha−1 for conventional and ecological management treatments, respectively

    The language of religious affiliation: social, emotional, and cognitive differences

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    Religious affiliation is an important identifying characteristic for many individuals and relates to numerous life outcomes including health, well-being, policy positions, and cognitive style. Using methods from computational linguistics, we examined language from 12,815 Facebook users in the United States and United Kingdom who indicated their religious affiliation. Religious individuals used more positive emotion words (β = .278, p < .0001) and social themes such as family (β = .242, p < .0001), while nonreligious people expressed more negative emotions like anger (β = −.427, p < .0001) and categories related to cognitive processes, like tentativeness (β = −.153, p < .0001). Nonreligious individuals also used more themes related to the body (β = −.265, p < .0001) and death (β = −.247, p < .0001). The findings offer directions for future research on religious affiliation, specifically in terms of social, emotional, and cognitive differences

    Microgeographically diverse Plasmodium vivax populations at the Thai-Myanmar border

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    Malaria transmission along international borders of the Greater Mekong Subregion is a big challenge for regional malaria elimination. At the Thai-Myanmar border, Plasmodium falciparum cases have dropped dramatically; however, increasing P. vivax prevalence and the emerging reports on hidden malaria burden due to asymptomatic infections demand attention. We conducted cross-sectional surveys to detect asymptomatic malaria infections in a small village located at Thai-Myanmar border and genotyped P. vivax infections in order to understand the level of genetic diversity on such a microgeographic scale. PCR/RFLP and DNA sequencing identified high levels of genetic polymorphisms at both Pvmsp3ι and Pvmsp3β loci among P. vivax infections. Combining the PCR/RFLP patterns of Pvmsp3ι and Pvmsp3β, a total of 10 genotypes were observed among 17 samples, while concatenated DNA sequences of Pvmsp3ι and 3β generated 14 haplotypes with haplotype diversity of 0.97. These markedly diverse parasites on a microgeographic scale suggest the circulation of a considerably large parasite population at the international border

    Microgeographic Heterogeneity of Border Malaria During Elimination Phase, Yunnan Province, China, 2011–2013

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    To identify township-level high-risk foci of malaria transmission in Yunnan Province, China, along the international border, we retrospectively reviewed data collected in hospitals and clinics of 58 townships in 4 counties during 2011–2013. We analyzed spatiotemporal distribution, especially hot spots of confirmed malaria, using geographic information systems and Getis-Ord Gi*(d) cluster analysis. Malaria incidence, transmission seasonality, and Plasmodium vivax:P. falciparum ratio remained almost unchanged from 2011 to 2013, but heterogeneity in distribution increased. The number of townships with confirmed malaria decreased significantly during the 3 years; incidence became increasingly concentrated within a few townships. High-/low-incidence clusters of P. falciparum shifted in location and size every year, whereas the locations of high-incidence P. vivax townships remained unchanged. All high-incidence clusters were located along the China–Myanmar border. Because of increasing heterogeneity in malaria distribution, microgeographic analysis of malaria transmission hot spots provided useful information for designing targeted malaria intervention during the elimination phase

    Plasmodium falciparum populations from northeastern Myanmar display high levels of genetic diversity at multiple antigenic loci

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    Levels of genetic diversity of the malaria parasites and multiclonal infections are correlated with transmission intensity. In order to monitor the effect of strengthened malaria control efforts in recent years at the China-Myanmar border area, we followed the temporal dynamics of genetic diversity of three polymorphic antigenic markers msp1, msp2, and glurp in the Plasmodium falciparum populations. Despite reduced malaria prevalence in the region, parasite populations exhibited high levels of genetic diversity. Genotyping 258 clinical samples collected in four years detected a total of 22 PCR size alleles. Multiclonal infections were detected in 45.7% of the patient samples, giving a minimum multiplicity of infection of 1.41. The majority of alleles experienced significant temporal fluctuations through the years. Haplotype diversity based on the three-locus genotypes ranged from the lowest in 2009 at 0.33 to the highest in 2010 at 0.80. Sequencing of msp1 fragments from 36 random samples of five allele size groups detected 13 different sequences, revealing an additional layer of genetic complexity. This study suggests that despite reduced prevalence of malaria infections in this region, the parasite population size and transmission intensity remained high enough to allow effective genetic recombination of the parasites and continued maintenance of genetic diversity

    Microgeography and molecular epidemiology of malaria at the Thailand-Myanmar border in the malaria pre-elimination phase

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    BACKGROUND: Endemic malaria in Thailand continues to only exist along international borders. This pattern is frequently attributed to importation of malaria from surrounding nations. A microgeographical approach was used to investigate malaria cases in a study village along the Thailand–Myanmar border. METHODS: Three mass blood surveys were conducted during the study period (July and December 2011, and May 2012) and were matched to a cohort-based demographic surveillance system. Blood slides and filter papers were taken from each participant. Slides were cross-verified by an expert microscopist and filter papers were analysed using nested PCR. Cases were then mapped to households and analysed using spatial statistics. A risk factor analysis was done using mixed effects logistic regression. RESULTS: In total, 55 Plasmodium vivax and 20 Plasmodium falciparum cases (out of 547 participants) were detected through PCR, compared to six and two (respectively) cases detected by field microscopy. The single largest risk factor for infection was citizenship. Many study participants were ethnic Karen people with no citizenship in either Thailand or Myanmar. This subpopulation had over eight times the odds of malaria infection when compared to Thai citizens. Cases also appeared to cluster near a major drainage system and year–round water source within the study village. CONCLUSION: This research indicates that many cases of malaria remain undiagnosed in the region. The spatial and demographic clustering of cases in a sub-group of the population indicates either transmission within the Thai village or shared exposure to malaria vectors outside of the village. While it is possible that malaria is imported to Thailand from Myanmar, the existence of undetected infections, coupled with an ecological setting that is conducive to malaria transmission, means that indigenous transmission could also occur on the Thai side of the border. Improved, timely, and active case detection is warranted
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