Singular value decomposition (SVD) analysis is a powerful tool for identifying different spatial ... more Singular value decomposition (SVD) analysis is a powerful tool for identifying different spatial and timing variation patterns in many fields of researches. Recently we applied complex SVD method to space harmonic analysis of a 13-cell defecting cavity that is built and installed in the APS linac injector for beam phase space characterization and emittance exchange experiments. Real and imaginary space harmonics components are extracted from CST simulated data. Fields inside the iris were expressed in analytic forms and produced good agreement. Work is underway to implement the results into elegant simulation model. INTRODUCTION SVD analysis [1] is a powerful tool for identifying various system spatial and timing variation patterns. Recently we applied complex SVD analysis to extract space harmonics from CST simulated deflecting cavity data. We were able to extract the real and imaginary parts of the space harmonics, from which the field inside the iris can be expressed analytically, which can be used to develop simplified model for beam simulations of deflecting cavities. A BRIEF DESCRIPTION OF SVD ANALYSIS A system matrix consists of m spatial columns, each contains n equal samples of time or another dimension. A=[A11 A12 A13 ⋯ A1m A21 A22 A23 ⋯ A2m ⋮ ⋯ ⋯ ⋯ ⋮ An1 An2 ⋯ ⋯ Anm ] SVD analysis converts A into U, V and Σ matrices: A=U ΣV U=[U 1 U 2 ⋯ Um] V=[V 1 V 2 ⋯ V n ] Σ=[λ1 0 0 ⋯ 0 0 λ2 0 ⋯ 0 ⋮ ⋯ ⋯ ⋯ ⋮ 0 ⋯ ⋯ ⋯ λm 0 ⋯ ⋯ ⋯ 0 ] Here λ1... λm are eigenvalues and each of the vector of U and V matrices are spatial and timing vectors corresponding to eigenvalues. For analysis of cavities the field components are phasors and are generally expressed in complex values. For a complex matrix A, we construct a matrix AA that consists of 2×2 block matrices from a construction matrix Q [2]:
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
SIR -Michael Alvarez, in his Recruiters article 'System-ready scientists' (Nature 447, 612; 2007)... more SIR -Michael Alvarez, in his Recruiters article 'System-ready scientists' (Nature 447, 612; 2007) advises young scientists to consider how they can fit into and enhance the labour force, even though this course might seem dehumanizing to them. He advises universities to gather information from government and industry about their 'design specifications' for incoming talent, to help them develop graduate training programmes that produce suitably qualified trainees. I believe such an approach is a backwards step. Many scientists study and do research out of irrepressible curiosity and sheer love for the subject. It is true that the US academic funding system created a glut of postdoctoral researchers who have had to find alternatives to conventional career paths, but 'publish or perish' is a relatively harmless dictum compared with 'profit or perish' . Rather than helping universities strip the creativity, intuition and joy of discovery from scientists while they train, government and industry should be willing to spend money, within their pragmatic frameworks, to acknowledge that scientific research is a fundamentally creative pursuit.
Suspended solids and P runoff were measured under four rice establishment methods. • Total suspen... more Suspended solids and P runoff were measured under four rice establishment methods. • Total suspended solids losses from direct seeding were significant higher than seedling transplanting. • Direct seeding significantly increased total P, dissolved P, and particulate P losses in runoff. • Particulate P was the main form of P lost in runoff from paddy field. • Total suspended solids had significant positive correlations with total P, dissolved P, and particulate P.
The precipitation legacy effect, defined as the impact of historical precipitation (PPT) on extan... more The precipitation legacy effect, defined as the impact of historical precipitation (PPT) on extant ecosystem dynamics, has been recognized as an important driver in shaping the temporal variability of dryland aboveground net primary production (ANPP) and soil respiration. How the PPT legacy influences whole ecosystem-level carbon (C) fluxes has rarely been quantitatively assessed, particularly at longer temporal scales. We parameterized a process-based ecosystem model to a semiarid savanna ecosystem in the southwestern USA, calibrated and evaluated the model performance based on 7 years of eddy-covariance measurements, and conducted two sets of simulation experiments to assess interdecadal and interannual PPT legacy effects over a 30-year simulation period. The results showed that decreasing the previous period/year PPT (dry legacy) always increased subsequent net ecosystem production (NEP) whereas increasing the previous period/year PPT (wet legacy) decreased NEP. The simulated dry-legacy impacts mostly increased subsequent gross ecosystem production (GEP) and reduced ecosystem respiration (R e ), but the wet legacy mostly reduced GEP and increased R e . Although the direction and magnitude of GEP and R e responses to the simulated dry and wet legacies were influenced by both the previous and current PPT conditions, the NEP responses were predominantly determined by the previous PPT characteristics including rainfall amount, seasonality and event size distribution. Larger PPT difference between periods/years resulted in larger legacy impacts, with dry legacies fostering more C sequestration and wet legacies more C release. The carryover of soil N between periods/years was mainly responsible for the GEP responses, while the carryovers of plant biomass, litter and soil organic matter were mainly responsible for the R e responses. These simulation results suggest that previous PPT conditions can exert substantial legacy impacts on current ecosystem C balance, which should be taken into account while assessing the response of dryland ecosystem C dynamics to future PPT regime changes.
Climate-smart agriculture (CSA) management practices (e.g., conservation tillage, cover crops, an... more Climate-smart agriculture (CSA) management practices (e.g., conservation tillage, cover crops, and biochar applications) have been widely adopted to enhance soil organic carbon (SOC) sequestration and to reduce greenhouse gas emissions while ensuring crop productivity. However, current measurements regarding the influences of CSA management practices on SOC sequestration diverge widely, making it difficult to derive conclusions about individual and combined CSA management effects and bringing large uncertainties in quantifying the potential of the agricultural sector to mitigate climate change. We conducted a meta-analysis of 3,049 paired measurements from 417 peer-reviewed articles to examine the effects of three common CSA management practices on SOC sequestration as well as the environmental controlling factors. We found that, on average, biochar applications represented the most effective approach for increasing SOC content (39%), followed by cover crops (6%) and conservation tillage (5%). Further analysis suggested that the effects of This article is protected by copyright. All rights reserved. CSA management practices were more pronounced in areas with relatively warmer climates or lower nitrogen fertilizer inputs. Our meta-analysis demonstrated that, through adopting CSA practices, cropland could be an improved carbon sink. We also highlight the importance of considering local environmental factors (e.g., climate and soil conditions and their combination with other management practices) in identifying appropriate CSA practices for mitigating greenhouse gas emissions while ensuring crop productivity.
Objectives: Greenhouse pot studies were conducted to assess the abilities of two arbuscular mycor... more Objectives: Greenhouse pot studies were conducted to assess the abilities of two arbuscular mycorrhizal fungi (AMF) namely, Rhizophagus clarus (Rc) and R. intraradices (Ri) to enhance biomass productivity of big bluestem (Andropogon gerardii), as a complementary bioenergy feedstock to and switchgrass (Panicum virgatum). Methodology and results: Big bluestem (BB) and switchgrass (SG) were grown in a soilless substrate adjusted to pH=6.5 or 4.5 and inoculated separately with Rc and Ri. Plants were grown in the greenhouse for 12 weeks. Results show that AMF significantly enhanced biomass productivity of the grasses over corresponding controls, regardless of pH. Substrate inoculation with Rc produced the highest and similar total BB biomass at pH=6.5 and 4.5. However, biomass partitioning into shoot and root differed with pH. Inoculation with Ri produced the highest and similar total SG biomass at pH=6.5 and 4.5. SG biomass was more equally distributed at both pHs. Conclusion and application of findings: Differences in substrate partitioning into shoot and root biomass shown by Rc-inoculated BB at 4.5, appeared to be consistent with Rc endowing BB the capacity to maintain both relatively high shoot as well as root biomass at pH=4.5. This pattern of substrate partitioning was not shown by Rc-or Ri-inoculated BB grown at pH =6.5, or Ri-inoculated BB grown at pH=4.5. Neither was the pattern shown by Rc-or Ri-inoculated SG, which maintained relatively similar R/S ratios regardless of pH. The usual biomass partitioning by BB at pH=4.5 deserves further investigation. Different patterns of biomass partitioning notwithstanding, results of this study strongly suggest that BB could complement SG, the model biofuel feedstock, especially under acidic substrate conditions.
The dynamic ensemble selection of classifiers is an effective approach for processing labelimbala... more The dynamic ensemble selection of classifiers is an effective approach for processing labelimbalanced data classifications. However, such a technique is prone to overfitting, owing to the lack of regularization methods and the dependence of the aforementioned technique on local geometry. In this study, focusing on binary imbalanced data classification, a novel dynamic ensemble method, namely adaptive ensemble of classifiers with regularization (AER), is proposed, to overcome the stated limitations. The method solves the overfitting problem through implicit regularization. Specifically, it leverages the properties of stochastic gradient descent to obtain the solution with the minimum norm, thereby achieving regularization; furthermore, it interpolates the ensemble weights by exploiting the global geometry of data to further prevent overfitting. According to our theoretical proofs, the seemingly complicated AER paradigm, in addition to its regularization capabilities, can actually reduce the asymptotic time and memory complexities of several other algorithms. We evaluate the proposed AER method on seven benchmark imbalanced datasets from the UCI machine learning repository and one artificially generated GMM-based dataset with five variations. The results show that the proposed algorithm outperforms the major existing algorithms based on multiple metrics in most cases, and two hypothesis tests (McNemar's and Wilcoxon tests) verify the statistical significance further. In addition, the proposed method has other preferred properties such as special advantages in dealing with highly imbalanced data, and it pioneers the research on the regularization for dynamic ensemble methods.
Share-copy and redistribute the material in any medium or format. Adapt-remix, transform, and bui... more Share-copy and redistribute the material in any medium or format. Adapt-remix, transform, and build upon the material for any purpose, even commercially. The licensor cannot revoke these freedoms as long as you follow the license terms. Under the following terms: Attribution-You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. No additional restrictions You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.
Aluminum (Al) toxicity is a major constraint to plant growth and crop yield in acid soils. Tomato... more Aluminum (Al) toxicity is a major constraint to plant growth and crop yield in acid soils. Tomato cultivars are especially susceptible to excessive Al 3+ accumulated in the root zone. In this study, tomato plants were grown in a hydroponic culture system supplemented with 50 µM AlK(SO 4 ) 2 . Seeds harvested from Al-treated plants contained a significantly higher Al content than those grown in the control hydroponic solution. In this study, these Al-enriched tomato seeds (harvested from Al-treated tomato plants) were germinated in 50 µM AlK(SO 4 ) 2 solution in a homopiperazine-1,4-bis(2-ethanesulfonic acid) buffer (pH 4.0), and the control solution which contained the buffer only. Proteomes of radicles were analyzed quantitatively by mass spectrometry employing isobaric tags for relative and absolute quantitation (iTRAQ ® ). The proteins identified were assigned to molecular functional groups and cellular metabolic pathways using MapMan. Among the proteins whose abundance levels changed significantly were: a number of transcription factors; proteins regulating gene silencing and programmed cell death; proteins in primary
1. Intensified inter-annual fluctuations in precipitation could profoundly impact terrestrial eco... more 1. Intensified inter-annual fluctuations in precipitation could profoundly impact terrestrial ecosystems. However, how changes previous-year precipitation influence current ecosystem functioning (e.g., resource use efficiency) in semi-arid regions remains unclear. 2. In this study, water use efficiency (WUE) and light use efficiency (LUE) were investigated in a multi-year precipitation gradient experiment with seven treatment levels: 20%, 40% and 60% decreases and 20%, 40% and 60% increases in the amount of natural rainfall plus ambient precipitation. Plots receiving 60% less precipitation were representative of extreme dry years whereas the other treatment levels fell within the normal year-to-year range in precipitation change. Measurements made in both the post-treatment period (2013-2015) and the treatment period (2010-2012) provided an opportunity to quantify the legacy effects of precipitation on resource use efficiency (RUE). 3. Sensitivities of LUE to previous-year precipitation were not changed among treatments in 2013. However, asymmetric responses of RUEs (i.e., WUE and LUE) to previous-year precipitation were found in 2014-2015. WUE2014, WUE2015, LUE2014, and LUE2015 responded more strongly to previous normal decreased than increased precipitation. Importantly, they were more sensitive to previous extreme dry year (represented by 60% precipitation reduction) than normal wet year (represented by 60% precipitation increment). Aboveground net primary productivity (ANPP) rather than resource absorption (Ruptake) drove these asymmetric responses of RUE, and biomass of grasses further explained the asymmetric responses of ANPP. 4. This study reveals the non-linear responses of RUE to previous-year precipitation and highlighted that the legacy effects of precipitation on RUE can be ascribed to the changes in vegetation composition. Our findings can facilitate the prediction of the legacy effects of precipitation variation on grassland ecosystem functions in the future.
Global change can greatly affect plant productivity and subsequently litter input to soil, with p... more Global change can greatly affect plant productivity and subsequently litter input to soil, with potential impacts on soil carbon (C) fluxes. However, the effects of litter layer in mediating C cycling and budget at an ecosystem scale are still not clear. As part of a long‐term litter fall manipulation experiment in a temperate steppe on the Mongolian Plateau, this study was conducted to explore effects of litter removal and addition on ecosystem C budget and the associated mechanisms. Overall, litter removal enhanced photosynthetic active radiation (PAR) at soil surface by 31.0%, but litter addition reduced it by 26.5%. Litter removal decreased soil inorganic nitrogen (SIN) content at the depth of 0–10 cm by 13.6%, but litter addition enhanced it by 14.1%. Litter removal increased legume abundance by 131.1%, whereas litter addition enhanced grass abundance by 30.7% but decreased forb abundance by 33.1%. Litter removal increased gross ecosystem productivity (GEP) through enhancing PA...
Changing precipitation regimes can profoundly affect plant growth in terrestrial ecosystems, espe... more Changing precipitation regimes can profoundly affect plant growth in terrestrial ecosystems, especially in arid and semi-arid regions. However, how changing precipitation, especially extreme precipitation events, alters plant diversity and community composition is still poorly understood. A 3-year field manipulative experiment with seven precipitation treatments, including -60%, -40%, -20%, 0% (as a control), + 20%, + 40%, and + 60% of ambient growing-season precipitation, was conducted in a semi-arid steppe in the Mongolian Plateau. Results showed total plant community cover and forb cover were enhanced with increased precipitation and reduced under decreased precipitation, whereas grass cover was suppressed under the -60% treatment only. Plant community and grass species richness were reduced by the -60% treatment only. Moreover, our results demonstrated that total plant community cover was more sensitive to decreased than increased precipitation under normal and extreme precipitation change, and species richness was more sensitive to decreased than increased precipitation under extreme precipitation change. The community composition and low field water holding capacity may drive this asymmetric response. Accumulated changes in community cover may eventually lead to changes in species richness. However, compared to control, Shannon-Weiner index (H) did not respond to any precipitation treatment, and Pielou's evenness index (E) was reduced under the + 60% treatment across the 3 year, but not in each year. Thus, the findings suggest that plant biodiversity in the semi-arid steppe may have a strong resistance to precipitation pattern changes through adjusting its composition in a short term.
Bitter melon (Momordica charantia L.) has been used for anti-diabetes treatment for decades. Indi... more Bitter melon (Momordica charantia L.) has been used for anti-diabetes treatment for decades. Indian and Chinese bitter melons (BM) are two commonly produced cultivars in the US market. This study has comparatively evaluated the effects of two processing methods (fresh and freeze-drying) on Chinese and Indian BM by measuring their bioactivity in terms of total phenolic content (TPC), total triterpene content (TTC), antioxidant activity, and antidiabetic properties using the DPPH free radical scavenging and reducing power assays, and the α-amylase and α-glucosidase inhibition assays. The TPC (GAE mg/g dw) in freeze-dried BM were 6.03 and 6.09, and in fresh BM were 4.81 and 4.83 for Indian and Chinese BM, respectively. The TTC (OAE mg/g dw) in Indian BM were 7.25 and 5.63, and in Chinese BM were 5.88 and 3.87 for fresh and freeze-dried samples, respectively. TPC and TTC in the freeze-dried BM samples were significantly higher than that in the fresh ones (p < 0.05). The DPPH IC50 of India BM was significantly lower than that of Chinese BM (p < 0.05). All BM samples ranged from 9.18 to 18.6 mg/ml. The reducing power was significantly different between Indian and Chinese BM (p < 0.01) for fresh samples, but after freeze-drying, there was no detectable difference in reducing power (p ≥ 0.05). The Indian BM showed a significantly stronger α-glucosidase inhibition effect as compared to the Chinese BM. TTC was positively correlated with reducing power (p < 0.05). TPC was negatively correlated with α-amylase inhibition efficiency (p < 0.05).
Powdery mildew caused by Erysiphe pulchra is one of the most destructive diseases of flowering do... more Powdery mildew caused by Erysiphe pulchra is one of the most destructive diseases of flowering dogwoods (Cornus florida L.). Control of powdery mildew relies heavily on chemical fungicides. Developing genetic resistance and planting powdery mildew resistant cultivars is a desirable long term control strategy for the disease. Information on inheritance characteristics associated with powdery mildew resistance in C. florida is needed to facilitate development of breeding strategies for a new generation of powdery mildew resistant cultivars. The objectives of this study were to determine broad-sense heritability, genetic gain and minimum number of effective genes associated with resistance to powdery mildew in C. florida. Progeny segregating for powdery mildew resistance were developed through controlled crosses between susceptible cultivar [Cherokee Princess (CP)], resistant selection (R14) and moderately resistant cultivars [MI9 and Cherokee Brave (CB)]. The parents and progeny were evaluated for resistance/ susceptibility to powdery mildew under greenhouse conditions and estimates for broad-sense heritability, genetic gain and minimum number of effective genes was determined. Broad-sense heritability ranged from 60% to 88% while corresponding narrow-sense heritability ranged from 53% to 86.6%. The highest predicted genetic gain for powdery mildew resistance was obtained in the R14 x CP (78%) and CB x MI9 (61%) crosses while the lowest genetic gain was observed in the CP x MI9 (34%) and MI9 x CB (36%) crosses. These results indicate that CB x MI9 and R14 x CP crosses are best parental lines for developing resistance to powdery mildew among the genotypes tested. Use of these parental lines and understanding the gene flow of resistance to powdery mildew in dogwoods will help researchers to develop a targeted breeding approach in generating new generation of resistant cultivars.
This study aimed to identify the aluminum (Al)-induced proteomes in tomato (Solanum lycopersicum,... more This study aimed to identify the aluminum (Al)-induced proteomes in tomato (Solanum lycopersicum, "Micro-Tom") after long-term exposure to the stress factor. Plants were treated in Magnavaca's solution (pH 4.5) supplemented with 7.5 μM Al(3+) ion activity over a 4 month period beginning at the emergence of flower buds and ending when the lower mature leaves started to turn yellow. Proteomes were identified using a 8-plex isobaric tags for relative and absolute quantification (iTRAQ) labeling strategy followed by a two-dimensional (high- and low-pH) chromatographic separation and final generation of tandem mass spectrometry (MS/MS) spectra of tryptic peptides on an LTQ-Orbitrap Elite mass spectrometer. Principal component analysis revealed that the Al-treatment had induced systemic alterations in the proteomes from roots and leaves but not seed tissues. The significantly changed root proteins were shown to have putative functions in Al(3+) ion uptake and transportation,...
Singular value decomposition (SVD) analysis is a powerful tool for identifying different spatial ... more Singular value decomposition (SVD) analysis is a powerful tool for identifying different spatial and timing variation patterns in many fields of researches. Recently we applied complex SVD method to space harmonic analysis of a 13-cell defecting cavity that is built and installed in the APS linac injector for beam phase space characterization and emittance exchange experiments. Real and imaginary space harmonics components are extracted from CST simulated data. Fields inside the iris were expressed in analytic forms and produced good agreement. Work is underway to implement the results into elegant simulation model. INTRODUCTION SVD analysis [1] is a powerful tool for identifying various system spatial and timing variation patterns. Recently we applied complex SVD analysis to extract space harmonics from CST simulated deflecting cavity data. We were able to extract the real and imaginary parts of the space harmonics, from which the field inside the iris can be expressed analytically, which can be used to develop simplified model for beam simulations of deflecting cavities. A BRIEF DESCRIPTION OF SVD ANALYSIS A system matrix consists of m spatial columns, each contains n equal samples of time or another dimension. A=[A11 A12 A13 ⋯ A1m A21 A22 A23 ⋯ A2m ⋮ ⋯ ⋯ ⋯ ⋮ An1 An2 ⋯ ⋯ Anm ] SVD analysis converts A into U, V and Σ matrices: A=U ΣV U=[U 1 U 2 ⋯ Um] V=[V 1 V 2 ⋯ V n ] Σ=[λ1 0 0 ⋯ 0 0 λ2 0 ⋯ 0 ⋮ ⋯ ⋯ ⋯ ⋮ 0 ⋯ ⋯ ⋯ λm 0 ⋯ ⋯ ⋯ 0 ] Here λ1... λm are eigenvalues and each of the vector of U and V matrices are spatial and timing vectors corresponding to eigenvalues. For analysis of cavities the field components are phasors and are generally expressed in complex values. For a complex matrix A, we construct a matrix AA that consists of 2×2 block matrices from a construction matrix Q [2]:
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
SIR -Michael Alvarez, in his Recruiters article 'System-ready scientists' (Nature 447, 612; 2007)... more SIR -Michael Alvarez, in his Recruiters article 'System-ready scientists' (Nature 447, 612; 2007) advises young scientists to consider how they can fit into and enhance the labour force, even though this course might seem dehumanizing to them. He advises universities to gather information from government and industry about their 'design specifications' for incoming talent, to help them develop graduate training programmes that produce suitably qualified trainees. I believe such an approach is a backwards step. Many scientists study and do research out of irrepressible curiosity and sheer love for the subject. It is true that the US academic funding system created a glut of postdoctoral researchers who have had to find alternatives to conventional career paths, but 'publish or perish' is a relatively harmless dictum compared with 'profit or perish' . Rather than helping universities strip the creativity, intuition and joy of discovery from scientists while they train, government and industry should be willing to spend money, within their pragmatic frameworks, to acknowledge that scientific research is a fundamentally creative pursuit.
Suspended solids and P runoff were measured under four rice establishment methods. • Total suspen... more Suspended solids and P runoff were measured under four rice establishment methods. • Total suspended solids losses from direct seeding were significant higher than seedling transplanting. • Direct seeding significantly increased total P, dissolved P, and particulate P losses in runoff. • Particulate P was the main form of P lost in runoff from paddy field. • Total suspended solids had significant positive correlations with total P, dissolved P, and particulate P.
The precipitation legacy effect, defined as the impact of historical precipitation (PPT) on extan... more The precipitation legacy effect, defined as the impact of historical precipitation (PPT) on extant ecosystem dynamics, has been recognized as an important driver in shaping the temporal variability of dryland aboveground net primary production (ANPP) and soil respiration. How the PPT legacy influences whole ecosystem-level carbon (C) fluxes has rarely been quantitatively assessed, particularly at longer temporal scales. We parameterized a process-based ecosystem model to a semiarid savanna ecosystem in the southwestern USA, calibrated and evaluated the model performance based on 7 years of eddy-covariance measurements, and conducted two sets of simulation experiments to assess interdecadal and interannual PPT legacy effects over a 30-year simulation period. The results showed that decreasing the previous period/year PPT (dry legacy) always increased subsequent net ecosystem production (NEP) whereas increasing the previous period/year PPT (wet legacy) decreased NEP. The simulated dry-legacy impacts mostly increased subsequent gross ecosystem production (GEP) and reduced ecosystem respiration (R e ), but the wet legacy mostly reduced GEP and increased R e . Although the direction and magnitude of GEP and R e responses to the simulated dry and wet legacies were influenced by both the previous and current PPT conditions, the NEP responses were predominantly determined by the previous PPT characteristics including rainfall amount, seasonality and event size distribution. Larger PPT difference between periods/years resulted in larger legacy impacts, with dry legacies fostering more C sequestration and wet legacies more C release. The carryover of soil N between periods/years was mainly responsible for the GEP responses, while the carryovers of plant biomass, litter and soil organic matter were mainly responsible for the R e responses. These simulation results suggest that previous PPT conditions can exert substantial legacy impacts on current ecosystem C balance, which should be taken into account while assessing the response of dryland ecosystem C dynamics to future PPT regime changes.
Climate-smart agriculture (CSA) management practices (e.g., conservation tillage, cover crops, an... more Climate-smart agriculture (CSA) management practices (e.g., conservation tillage, cover crops, and biochar applications) have been widely adopted to enhance soil organic carbon (SOC) sequestration and to reduce greenhouse gas emissions while ensuring crop productivity. However, current measurements regarding the influences of CSA management practices on SOC sequestration diverge widely, making it difficult to derive conclusions about individual and combined CSA management effects and bringing large uncertainties in quantifying the potential of the agricultural sector to mitigate climate change. We conducted a meta-analysis of 3,049 paired measurements from 417 peer-reviewed articles to examine the effects of three common CSA management practices on SOC sequestration as well as the environmental controlling factors. We found that, on average, biochar applications represented the most effective approach for increasing SOC content (39%), followed by cover crops (6%) and conservation tillage (5%). Further analysis suggested that the effects of This article is protected by copyright. All rights reserved. CSA management practices were more pronounced in areas with relatively warmer climates or lower nitrogen fertilizer inputs. Our meta-analysis demonstrated that, through adopting CSA practices, cropland could be an improved carbon sink. We also highlight the importance of considering local environmental factors (e.g., climate and soil conditions and their combination with other management practices) in identifying appropriate CSA practices for mitigating greenhouse gas emissions while ensuring crop productivity.
Objectives: Greenhouse pot studies were conducted to assess the abilities of two arbuscular mycor... more Objectives: Greenhouse pot studies were conducted to assess the abilities of two arbuscular mycorrhizal fungi (AMF) namely, Rhizophagus clarus (Rc) and R. intraradices (Ri) to enhance biomass productivity of big bluestem (Andropogon gerardii), as a complementary bioenergy feedstock to and switchgrass (Panicum virgatum). Methodology and results: Big bluestem (BB) and switchgrass (SG) were grown in a soilless substrate adjusted to pH=6.5 or 4.5 and inoculated separately with Rc and Ri. Plants were grown in the greenhouse for 12 weeks. Results show that AMF significantly enhanced biomass productivity of the grasses over corresponding controls, regardless of pH. Substrate inoculation with Rc produced the highest and similar total BB biomass at pH=6.5 and 4.5. However, biomass partitioning into shoot and root differed with pH. Inoculation with Ri produced the highest and similar total SG biomass at pH=6.5 and 4.5. SG biomass was more equally distributed at both pHs. Conclusion and application of findings: Differences in substrate partitioning into shoot and root biomass shown by Rc-inoculated BB at 4.5, appeared to be consistent with Rc endowing BB the capacity to maintain both relatively high shoot as well as root biomass at pH=4.5. This pattern of substrate partitioning was not shown by Rc-or Ri-inoculated BB grown at pH =6.5, or Ri-inoculated BB grown at pH=4.5. Neither was the pattern shown by Rc-or Ri-inoculated SG, which maintained relatively similar R/S ratios regardless of pH. The usual biomass partitioning by BB at pH=4.5 deserves further investigation. Different patterns of biomass partitioning notwithstanding, results of this study strongly suggest that BB could complement SG, the model biofuel feedstock, especially under acidic substrate conditions.
The dynamic ensemble selection of classifiers is an effective approach for processing labelimbala... more The dynamic ensemble selection of classifiers is an effective approach for processing labelimbalanced data classifications. However, such a technique is prone to overfitting, owing to the lack of regularization methods and the dependence of the aforementioned technique on local geometry. In this study, focusing on binary imbalanced data classification, a novel dynamic ensemble method, namely adaptive ensemble of classifiers with regularization (AER), is proposed, to overcome the stated limitations. The method solves the overfitting problem through implicit regularization. Specifically, it leverages the properties of stochastic gradient descent to obtain the solution with the minimum norm, thereby achieving regularization; furthermore, it interpolates the ensemble weights by exploiting the global geometry of data to further prevent overfitting. According to our theoretical proofs, the seemingly complicated AER paradigm, in addition to its regularization capabilities, can actually reduce the asymptotic time and memory complexities of several other algorithms. We evaluate the proposed AER method on seven benchmark imbalanced datasets from the UCI machine learning repository and one artificially generated GMM-based dataset with five variations. The results show that the proposed algorithm outperforms the major existing algorithms based on multiple metrics in most cases, and two hypothesis tests (McNemar's and Wilcoxon tests) verify the statistical significance further. In addition, the proposed method has other preferred properties such as special advantages in dealing with highly imbalanced data, and it pioneers the research on the regularization for dynamic ensemble methods.
Share-copy and redistribute the material in any medium or format. Adapt-remix, transform, and bui... more Share-copy and redistribute the material in any medium or format. Adapt-remix, transform, and build upon the material for any purpose, even commercially. The licensor cannot revoke these freedoms as long as you follow the license terms. Under the following terms: Attribution-You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. No additional restrictions You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.
Aluminum (Al) toxicity is a major constraint to plant growth and crop yield in acid soils. Tomato... more Aluminum (Al) toxicity is a major constraint to plant growth and crop yield in acid soils. Tomato cultivars are especially susceptible to excessive Al 3+ accumulated in the root zone. In this study, tomato plants were grown in a hydroponic culture system supplemented with 50 µM AlK(SO 4 ) 2 . Seeds harvested from Al-treated plants contained a significantly higher Al content than those grown in the control hydroponic solution. In this study, these Al-enriched tomato seeds (harvested from Al-treated tomato plants) were germinated in 50 µM AlK(SO 4 ) 2 solution in a homopiperazine-1,4-bis(2-ethanesulfonic acid) buffer (pH 4.0), and the control solution which contained the buffer only. Proteomes of radicles were analyzed quantitatively by mass spectrometry employing isobaric tags for relative and absolute quantitation (iTRAQ ® ). The proteins identified were assigned to molecular functional groups and cellular metabolic pathways using MapMan. Among the proteins whose abundance levels changed significantly were: a number of transcription factors; proteins regulating gene silencing and programmed cell death; proteins in primary
1. Intensified inter-annual fluctuations in precipitation could profoundly impact terrestrial eco... more 1. Intensified inter-annual fluctuations in precipitation could profoundly impact terrestrial ecosystems. However, how changes previous-year precipitation influence current ecosystem functioning (e.g., resource use efficiency) in semi-arid regions remains unclear. 2. In this study, water use efficiency (WUE) and light use efficiency (LUE) were investigated in a multi-year precipitation gradient experiment with seven treatment levels: 20%, 40% and 60% decreases and 20%, 40% and 60% increases in the amount of natural rainfall plus ambient precipitation. Plots receiving 60% less precipitation were representative of extreme dry years whereas the other treatment levels fell within the normal year-to-year range in precipitation change. Measurements made in both the post-treatment period (2013-2015) and the treatment period (2010-2012) provided an opportunity to quantify the legacy effects of precipitation on resource use efficiency (RUE). 3. Sensitivities of LUE to previous-year precipitation were not changed among treatments in 2013. However, asymmetric responses of RUEs (i.e., WUE and LUE) to previous-year precipitation were found in 2014-2015. WUE2014, WUE2015, LUE2014, and LUE2015 responded more strongly to previous normal decreased than increased precipitation. Importantly, they were more sensitive to previous extreme dry year (represented by 60% precipitation reduction) than normal wet year (represented by 60% precipitation increment). Aboveground net primary productivity (ANPP) rather than resource absorption (Ruptake) drove these asymmetric responses of RUE, and biomass of grasses further explained the asymmetric responses of ANPP. 4. This study reveals the non-linear responses of RUE to previous-year precipitation and highlighted that the legacy effects of precipitation on RUE can be ascribed to the changes in vegetation composition. Our findings can facilitate the prediction of the legacy effects of precipitation variation on grassland ecosystem functions in the future.
Global change can greatly affect plant productivity and subsequently litter input to soil, with p... more Global change can greatly affect plant productivity and subsequently litter input to soil, with potential impacts on soil carbon (C) fluxes. However, the effects of litter layer in mediating C cycling and budget at an ecosystem scale are still not clear. As part of a long‐term litter fall manipulation experiment in a temperate steppe on the Mongolian Plateau, this study was conducted to explore effects of litter removal and addition on ecosystem C budget and the associated mechanisms. Overall, litter removal enhanced photosynthetic active radiation (PAR) at soil surface by 31.0%, but litter addition reduced it by 26.5%. Litter removal decreased soil inorganic nitrogen (SIN) content at the depth of 0–10 cm by 13.6%, but litter addition enhanced it by 14.1%. Litter removal increased legume abundance by 131.1%, whereas litter addition enhanced grass abundance by 30.7% but decreased forb abundance by 33.1%. Litter removal increased gross ecosystem productivity (GEP) through enhancing PA...
Changing precipitation regimes can profoundly affect plant growth in terrestrial ecosystems, espe... more Changing precipitation regimes can profoundly affect plant growth in terrestrial ecosystems, especially in arid and semi-arid regions. However, how changing precipitation, especially extreme precipitation events, alters plant diversity and community composition is still poorly understood. A 3-year field manipulative experiment with seven precipitation treatments, including -60%, -40%, -20%, 0% (as a control), + 20%, + 40%, and + 60% of ambient growing-season precipitation, was conducted in a semi-arid steppe in the Mongolian Plateau. Results showed total plant community cover and forb cover were enhanced with increased precipitation and reduced under decreased precipitation, whereas grass cover was suppressed under the -60% treatment only. Plant community and grass species richness were reduced by the -60% treatment only. Moreover, our results demonstrated that total plant community cover was more sensitive to decreased than increased precipitation under normal and extreme precipitation change, and species richness was more sensitive to decreased than increased precipitation under extreme precipitation change. The community composition and low field water holding capacity may drive this asymmetric response. Accumulated changes in community cover may eventually lead to changes in species richness. However, compared to control, Shannon-Weiner index (H) did not respond to any precipitation treatment, and Pielou's evenness index (E) was reduced under the + 60% treatment across the 3 year, but not in each year. Thus, the findings suggest that plant biodiversity in the semi-arid steppe may have a strong resistance to precipitation pattern changes through adjusting its composition in a short term.
Bitter melon (Momordica charantia L.) has been used for anti-diabetes treatment for decades. Indi... more Bitter melon (Momordica charantia L.) has been used for anti-diabetes treatment for decades. Indian and Chinese bitter melons (BM) are two commonly produced cultivars in the US market. This study has comparatively evaluated the effects of two processing methods (fresh and freeze-drying) on Chinese and Indian BM by measuring their bioactivity in terms of total phenolic content (TPC), total triterpene content (TTC), antioxidant activity, and antidiabetic properties using the DPPH free radical scavenging and reducing power assays, and the α-amylase and α-glucosidase inhibition assays. The TPC (GAE mg/g dw) in freeze-dried BM were 6.03 and 6.09, and in fresh BM were 4.81 and 4.83 for Indian and Chinese BM, respectively. The TTC (OAE mg/g dw) in Indian BM were 7.25 and 5.63, and in Chinese BM were 5.88 and 3.87 for fresh and freeze-dried samples, respectively. TPC and TTC in the freeze-dried BM samples were significantly higher than that in the fresh ones (p < 0.05). The DPPH IC50 of India BM was significantly lower than that of Chinese BM (p < 0.05). All BM samples ranged from 9.18 to 18.6 mg/ml. The reducing power was significantly different between Indian and Chinese BM (p < 0.01) for fresh samples, but after freeze-drying, there was no detectable difference in reducing power (p ≥ 0.05). The Indian BM showed a significantly stronger α-glucosidase inhibition effect as compared to the Chinese BM. TTC was positively correlated with reducing power (p < 0.05). TPC was negatively correlated with α-amylase inhibition efficiency (p < 0.05).
Powdery mildew caused by Erysiphe pulchra is one of the most destructive diseases of flowering do... more Powdery mildew caused by Erysiphe pulchra is one of the most destructive diseases of flowering dogwoods (Cornus florida L.). Control of powdery mildew relies heavily on chemical fungicides. Developing genetic resistance and planting powdery mildew resistant cultivars is a desirable long term control strategy for the disease. Information on inheritance characteristics associated with powdery mildew resistance in C. florida is needed to facilitate development of breeding strategies for a new generation of powdery mildew resistant cultivars. The objectives of this study were to determine broad-sense heritability, genetic gain and minimum number of effective genes associated with resistance to powdery mildew in C. florida. Progeny segregating for powdery mildew resistance were developed through controlled crosses between susceptible cultivar [Cherokee Princess (CP)], resistant selection (R14) and moderately resistant cultivars [MI9 and Cherokee Brave (CB)]. The parents and progeny were evaluated for resistance/ susceptibility to powdery mildew under greenhouse conditions and estimates for broad-sense heritability, genetic gain and minimum number of effective genes was determined. Broad-sense heritability ranged from 60% to 88% while corresponding narrow-sense heritability ranged from 53% to 86.6%. The highest predicted genetic gain for powdery mildew resistance was obtained in the R14 x CP (78%) and CB x MI9 (61%) crosses while the lowest genetic gain was observed in the CP x MI9 (34%) and MI9 x CB (36%) crosses. These results indicate that CB x MI9 and R14 x CP crosses are best parental lines for developing resistance to powdery mildew among the genotypes tested. Use of these parental lines and understanding the gene flow of resistance to powdery mildew in dogwoods will help researchers to develop a targeted breeding approach in generating new generation of resistant cultivars.
This study aimed to identify the aluminum (Al)-induced proteomes in tomato (Solanum lycopersicum,... more This study aimed to identify the aluminum (Al)-induced proteomes in tomato (Solanum lycopersicum, "Micro-Tom") after long-term exposure to the stress factor. Plants were treated in Magnavaca's solution (pH 4.5) supplemented with 7.5 μM Al(3+) ion activity over a 4 month period beginning at the emergence of flower buds and ending when the lower mature leaves started to turn yellow. Proteomes were identified using a 8-plex isobaric tags for relative and absolute quantification (iTRAQ) labeling strategy followed by a two-dimensional (high- and low-pH) chromatographic separation and final generation of tandem mass spectrometry (MS/MS) spectra of tryptic peptides on an LTQ-Orbitrap Elite mass spectrometer. Principal component analysis revealed that the Al-treatment had induced systemic alterations in the proteomes from roots and leaves but not seed tissues. The significantly changed root proteins were shown to have putative functions in Al(3+) ion uptake and transportation,...
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