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Long-term conservation agriculture increases nitrogen use efficiency by crops, land equivalent ratio and soil carbon stock in a subtropical rice-based cropping system
No full textConservation Agriculture (CA) is still a relatively new approach for intensively cultivated (3 crops yr-1) rice-based cropping systems that produce high crop yield and amounts of residues annually. With the recent development of transplanting of rice into tilled strips on non-puddled soil, CA could become feasible for rice-based cropping patterns. However, the effect of increased retention of crop residues on crop response to nitrogen (N) fertilization rate in strip tilled systems with the transplanted rice and other crops grown in the annual rotation is yet to be determined. For nine years, we have examined the effects of soil disturbance levels - strip tillage (ST) and conventional tillage (CT), two residue retention levels –15% residue by height (low residue, LR) and 30% residue (high residue, HR) and five N rates (60%, 80%, 100%, 120%, and 140% of the recommended N fertilizer doses (RFD)) for a rice-wheat-mungbean cropping sequence. The 100% RFD was 75, 100 and 20 kg N ha-1for rice, wheat, and mungbean, respectively. Rice yields were comparable between the two tillage systems for up to year-6, wheat for up to year-3 but mungbean yield markedly increased in ST from year-1; however, the land equivalent ratio increased from year-1, principally because of higher mungbean yield. Introduction of ST increased land equivalent ratio by 26% relative to CT, N use efficiency and partial factor productivity. Nitrogen fertilizer demand for maximum yield in ST was increased by about 10% for rice and 5% for mungbean but decreased by 5% for wheat. Although fertilizer N demand had increased in ST system due to higher yield than CT, the N requirement declined by50–90% when the same yield goal is considered for ST as for CT. The soil organic carbon stock (0–15 cm) after 8 years increased from 21.5 to 30.5 t ha-1 due to the effect of ST plus high crop residue retention. Annual gross margin increased by 57% in ST over CT practice and 26% in HR over LR retention. In conclusion, after 9 years practicing CA with increased residue retention under strip tillage, the crops had higher N use efficiency, grain yield, land equivalent ratio and annual gross margin in the rice-wheat-mungbean cropping system while the N fertilizer requirement increased minimally
Hsp90 and associated co-chaperones of the Malaria parasite
Get PDFHeat shock protein 90 (Hsp90) is one of the major guardians of cellular protein homeostasis, through its specialized molecular chaperone properties. While Hsp90 has been extensively studied in many prokaryotic and higher eukaryotic model organisms, its structural, functional, and biological properties in parasitic protozoans are less well defined. Hsp90 collaborates with a wide range of co-chaperones that fine-tune its protein folding pathway. Co-chaperones play many roles in the regulation of Hsp90, including selective targeting of client proteins, and the modulation of its ATPase activity, conformational changes, and post-translational modifications. Plasmodium falciparum is responsible for the most lethal form of human malaria. The survival of the malaria parasite inside the host and the vector depends on the action of molecular chaperones. The major cytosolic P. falciparum Hsp90 (PfHsp90) is known to play an essential role in the development of the parasite, particularly during the intra-erythrocytic stage in the human host. Although PfHsp90 shares significant sequence and structural similarity with human Hsp90, it has several major structural and functional differences. Furthermore, its co-chaperone network appears to be substantially different to that of the human host, with the potential absence of a key homolog. Indeed, PfHsp90 and its interface with co-chaperones represent potential drug targets for antimalarial drug discovery. In this review, we critically summarize the current understanding of the properties of Hsp90, and the associated co-chaperones of the malaria parasite
Exogenously applied proline enhances Morph-Physiological responses and yield of Drought-Stressed maize plants grown under different irrigation systems
Get PDFThe exogenous application of osmoprotectants [e.g., proline (Pro)] is an important approach for alleviating the adverse effects of abiotic stresses on plants. Field trials were conducted during the summers of 2017 and 2018 to determine the effects of deficit irrigation and exogenous application of Pro on the productivity, morph-physiological responses, and yield of maize grown under two irrigation systems [surface irrigation (SI) and drip irrigation (DI)]. Three deficit irrigation levels (I100, I85, and I70, representing 100, 85, and 70% of crop evapotranspiration, respectively) and two concentrations of Pro (Pro1 = 2 mM and Pro2 = 4 mM) were used in this study. The plants exposed to drought stress showed a significant reduction in plant height, dry matter, leaf area, chlorophyll content [soil plant analysis development (SPAD)], quantum efficiency of photosystem II [Fv/Fm, Fv/F0, and performance index (PI)], water status [membrane stability index (MSI) and relative water content (RWC)], and grain yield. The DI system increased crop growth and yield and reduced the irrigation water input by 30% compared with the SI system. The growth, water status, and yield of plants significantly decreased with an increase in the water stress levels under the SI system. Under the irrigation systems tested in this study, Pro1 and Pro2 increased plant height by 16 and 18%, RWC by 7 and 10%, MSI by 6 and 12%, PI by 6 and 19%, chlorophyll fluorescence by 7 and 11%, relative chlorophyll content by 9 and 14%, and grain yield by 10 and 14%, respectively, compared with Pro0 control treatment (no Pro). The interaction of Pro2 at I100 irrigation level in DI resulted in the highest grain yield (8.42 t ha–1). However, under the DI or SI system, exogenously applied Pro2 at I85 irrigation level may be effective in achieving higher water productivity and yield without exerting any harmful effects on the growth or yield of maize under limited water conditions. Our results demonstrated the importance of the application of Pro as a tolerance inducer of drought stress in maize
Genetic diversity and population structure of pigeonpea (Cajanus cajan [L.] Millspaugh) landraces grown in Benin revealed by Genotyping-By-Sequencing
Get PDFGenetic diversity studies provide important details on target trait availability and its variability, for the success of breeding programs. In this study, GBS approach was used to reveal a new structuration of genetic diversity and population structure of pigeonpea in Benin. We used a total of 688 high-quality Single Nucleotide Polymorphism markers for a total of 44 pigeonpea genotypes. The distribution of SNP markers on the 11 chromosomes ranged from 14 on chromosome 5 to 133 on chromosome 2. The Polymorphism Information Content and gene diversity values were 0.30 and 0.34 respectively. The analysis of population structure revealed four clear subpopulations. The Weighted Neighbor Joining tree agreed with structure analyses by grouping the 44 genotypes into four clusters. The PCoA revealed that genotypes from subpopulations 1, 2 and 3 intermixed among themselves. The Analysis of Molecular Variance showed 7% of the total variation among genotypes while the rest of variation (93%) was within genotypes from subpopulations indicating a high gene exchange (Nm = 7.13) and low genetic differentiation (PhiPT = 0.07) between subpopulations. Subpopulation 2 presented the highest mean values of number of different alleles (Na = 1.57), number of loci with private alleles (Pa = 0.11) and the percentage of polymorphic loci (P = 57.12%). We discuss our findings and demonstrate how the genetic diversity and the population structure of this specie can be used through the Genome Wide Association Studies and Marker-Assisted Selection to enhance genetic gain in pigeonpea breeding programs in Benin
Use of a penicillin allergy clinical decision rule to enable direct oral penicillin provocation: an international multicentre randomised control trial in an adult population (PALACE): study protocol
Get PDFIntroduction Penicillin allergies are highly prevalent in the healthcare setting and associated with the prescription of second-line inferior antibiotics. More than 85% of all penicillin allergy labels can be removed by skin testing and 96%–99% of low-risk penicillin allergy labels can be removed by direct oral challenge. An internally and externally validated clinical assessment tool for penicillin allergy, PEN-FAST, can identify a low-risk penicillin allergy without the need for skin testing; a score of less than 3 has a negative predictive value of 96.3% (95% CI, 94.1 to 97.8) for the presence of a penicillin allergy. It is hypothesised that PEN-FAST is a safe and effective tool for assessing penicillin allergy in an outpatient clinic setting.
Methods and analysis This is an international, multicentre randomised control trial using the PEN-FAST tool to risk-stratify penicillin allergy labels in adult outpatients. The study’s primary objective is to evaluate the non-inferiority of using PEN-FAST score-guided management with direct oral challenge compared with standard care (defined as prick and intradermal skin testing followed by oral penicillin challenge). Participants will be randomised 1:1 to the intervention arm (direct oral penicillin challenge) or standard of care arm (skin testing followed by oral penicillin challenge, if skin testing is negative). The sample size of 380 randomised patients (190 per treatment arm) is required to demonstrate non-inferiority.
Ethics and dissemination The study will be performed according to the guidelines of the Helsinki Declaration and is approved by the Austin Health Human Research Ethics Committee (HREC/62425/Austin-2020) in Melbourne Australia, Vanderbilt University Institutional Review Board (IRB #202174) in Tennessee, USA, Duke University Institutional Review Board (IRB #Pro00108461) in North Carolina, USA and McGill University Health Centre Research Ethics Board in Canada (PALACE/2022-7605). The results of this study will be published and presented in various scientific forums
Global position tracking control of PMSM servo system via internal model approach and experimental validations
No full textIn practical engineering, load torque disturbance and parameter uncertainties are two important factors, which may deteriorate the tracking accuracy of permanent magnet synchronous motor (PMSM) servo system. Therefore, its global position tracking control problem is a challenging task when the load torque disturbance is time-varying and the motor parameters are unknown. In this article, an internal model controller based on global robust output regulation (GROR) theory is proposed to achieve this control objective. In particular, we first formulate the global position tracking control problem as a GROR problem. Then, the GROR problem is converted into a global robust stabilization problem of an augmented system by constructing an appropriate internal model. Finally, we can stabilize the augmented system by a global stabilization controller instead of local stabilization controller used in the recent work, which guarantees global position tracking and disturbance rejection of PMSM servo system. The excellent position tracking performance of our design is demonstrated by both simulation and experimental results
Climate warming masks the negative effect of microplastics on plant-soil health in a silt loam soil
No full textMany anthropogenic pressures are being exerted on terrestrial ecosystems globally, perhaps the most pressing of which include microplastics (MPs; <5 mm in size) pollution and climate change, both of which may have unpredictable consequences on soil ecosystem functioning. We therefore hypothesized that a dual pressure (MPs and warming) on plant-soil functioning would be more severe than either stress alone. Thus, we studied the interactive effects of MPs and warming on soil quality and ecosystem multifunctionality. Maize (Zea mays L.) was grown for 6 weeks under ambient and warming (+5 °C) conditions in the absence (control) or presence (5 % loading) of either polyethylene (PE), polyvinylchloride (PVC), or biodegradable polyhydroxyalkanoate (PHA). We found that PHA stimulated microbial biomass and enzyme activity due to the additional C resources, thus changing soil quality and ecosystem multifunctionality under ambient temperature. However, the accelerated microbial growth in PHA-treated soils also promoted N immobilization and plant–microbe nutrient competition, consequently decreasing plant health index by 65 % relative to the Control. As PVC and PE are chemically more stable than PHA, they had limited effect on soil quality and plant health under ambient temperature in the short term (6 weeks). Most of the negative impacts of MPs only occurred under ambient temperature, with few effects evident under warming conditions. This suggested that the effect of heat stress (evidenced by stunted growth and chlorophyll content) was noticeably more acute than the effect of MPs. In conclusion, we showed that MPs do affect plant health, soil quality, and ecosystem multifunctionality but these effects on plant-soil health were not exacerbated by the effects of a warmer climate
How international humanitarian law will constrain the use of autonomous weapon systems in the conduct of hostilities
Get PDFThis thesis will assess International Humanitarian Law (IHL) Additional Protocol 1 (AP 1) compliance issues that may arise in the use of Autonomous Weapon Systems (AWSs) in the conduct of hostilities. The focus of this assessment will be on the use of AWSs to launch kinetic attacks. The basis for an assessment of AWSs will be identical to that of conventional weapons. AP 1 requires weapon systems to first be found to be in compliance with IHL weapons law before being subject to targeting law.
Novel compliance issues arise due to the use of autonomy in weapon systems. Algorithmically determined autonomy utilised to ‘decide’ to launch kinetic attacks raises questions of human control of a weapon system. AP 1 creates obligations on a human's decision to use force and the resulting kinetic attack. This is altered by the use of autonomy that controls the weapon system.
The focus therefore of any IHL evaluation must necessarily be on the computer that uses algorithmically determined autonomy to control AWSs. The type of algorithm that runs the weapon systems that this thesis will focus on is machine learning. Machine learning uses heuristics to provide the capability to improve AWSs performance over time. Setting the conditions for a constructive dialogue on AWSs, an AP 1 assessment on the lawfulness of AWSs will discuss both general issues; and additional issues that might arise in the use of autonomous weapon systems that improve upon their performance over time.
The use of algorithmically determined autonomy in kinetic attacks raises several controversies that must be assessed for weapons law and targeting law compliance. The use of Observe, Orient, Decide, Act Loop (OODA Loop) will be used to analyse whether human decision-making is being completely removed, or merely displaced from the targeting decision-making process. The operational context of how AWSs will be used will be assessed in temporal and geographic terms to better understand how technology has led to the displacement of human decision-making in weapon systems. Ultimately, this thesis will inform the reader of the legality and use of weapon systems that were once largely electro-mechanical platforms directly controlled by humans, to weapon systems that are increasingly cyber-physical controlled by algorithms
Assessing the social cohesion of a translocated pride of white lions integrated with wild tawny lions in South Africa, using social network analysis
Get PDFIn South Africa, lions are protected in national parks and smaller fenced reserves. Translocating lions between fenced reserves, whilst necessary to maintain genetic diversity, is disruptive and can impact survivorship and pride cohesion. Critical to translocation success is pride cohesion. White lions are a natural colour variant occurring in the Greater Kruger Park Region, where anthropogenic threats eliminated this population until reintroduction in 2006. Through social network analysis (SNA), the sociality of a released pride of captive-origin white and wild tawny lions was compared to two captive-origin and wild prides of tawny lions. Social interactions and pride dynamics were recorded for each pride. For all prides, cubs and subadults were central to the play network, while adults received the most social interactions. White and wild tawny adult males initiated more social interactions than captive-origin tawny males, whilst a keystone adult female was identified in each pride. For the constructed pride, social interactions were more evenly distributed, suggesting a high level of connectedness and cohesion. This is the first study to demonstrate that captive-origin white and wild tawny lions can form a socially functional pride, suggesting that white lions would survive in the wild in the absence of anthropogenic threats
The effect of hydrogen peroxide concentration and water temperature on yellowtail kingfish Seriola lalandi in a repeated bathing treatment
No full textHydrogen peroxide is routinely used in commercial yellowtail kingfish culture to treat monogenean infections. As the culture of this species expands into warmer geographical areas, this study aimed to compare the effects of a repeated exposure to different hydrogen peroxide concentrations at two rearing temperatures, 18 and 26 °C. The repeat bath occurred 14 days after the initial bath in line with commercial treatment regimes. The three concentrations tested were 85, 170 and 340 mg L−1, with bathing conducted for 30 min. Mortality occurred following the second bath at 340 mg L−1 at 26 °C.
The highest hydrogen peroxide dose caused epithelial lifting in gill filaments and significantly reduced the size and abundance of common mucus cells within the skin epithelium following the repeat bath in warm water. Despite the highest dose causing gill damage and mortality in warm water, there were no significant effects of hydrogen peroxide concentration on any of the conventional blood parameters, except in moribund fish. A novel measurement of plasma thiol oxidation, however, was found to be significantly elevated at the highest bathing concentration.
Whilst yellowtail kingfish appeared to be tolerant of the high concentration of hydrogen peroxide tested in the current study at ambient water temperature, these fish were not infected with monogeneans, and any such burden is likely to increase the susceptibility of the fish to the effects of hydrogen peroxide