624 research outputs found

    Mechanistic understanding of iron toxicity tolerance in contrasting rice varieties from Africa: 1. Morpho-physiological and biochemical responses

    Get PDF
    Iron (Fe) is a fundamental element involved in various plant metabolic processes. However, when Fe uptake is excessive, it becomes toxic to the plant and disrupts cellular homeostasis. The aim of this study was to determine the physiological and biochemical mechanisms underlying tolerance to Fe toxicity in contrasting rice varieties adapted to African environments. Four varieties (CK801 and Suakoko 8 (tolerant), Supa and IR64 (sensitive)) selected from our previous work were analysed in more detail, and the first part of this study reports morphological, physiological and biochemical responses induced by Fe toxicity in these four varieties. Morphological (shoot length, root length, number of lateral roots), physiological (photosynthesis rate, stomatal conductance, transpiration rate, fluorescence, relative water content and cell membrane stability) and biochemical (tissue Fe, chlorophyll pigments, soluble sugars, protein and starch) traits were measured, as appropriate, on both shoot and root tissues and at different time points during the stress period. Fe toxicity significantly (P ≤ 0.05) reduced growth and metabolism of all the four varieties. Tolerant varieties showed more lateral roots than the sensitive ones, under Fe toxic conditions as well as higher photosynthesis rate, chlorophyll content and cell membrane stability. Strong dilution of Fe concentration in cells was identified, as one of the additional tolerance mechanisms used by CK801, whereas Suakoko 8 mainly used strong mobilisation of carbohydrates at the early stage of the stress period to anticipate metabolite shortage. Traits associated with Fe toxicity tolerance in this study could be specifically targeted in trait-based breeding programs of superior lowland rice varieties tolerant of Fe toxicity

    Malaysian white shrimp (P. Vannamei) aquaculture: an application of stochastic frontier analysis on technical efficiency

    Get PDF
    Shrimp aquaculture is playing a vital role in Malaysian agriculture, especially its increasing contribution to economic growth. White shrimp aquaculture is not only the key player in brackish water shrimp aquaculture but also the largest contributor to Malaysian shrimp aquaculture.This study estimates technical efficiency and investigates factors affecting technical inefficiency of Malaysian white shrimp aquaculture.Stochastic frontier analysis with trans-log production model is applied in this study.Malaysian white shrimp aquaculture farmers have achieved an estimated average technical efficiency of 81.2 percent.Land ownership, shrimp seed size and seminar are the factors having significant impacts on technical inefficiency and thereby playing important roles in improving technical efficiency of this industry.This study suggests that seminar should be conducted by shrimp farming extension agents to enhance knowledge of shrimp farmers.Malaysian government should allocate lands and, provide technical and financial supports to develop this industry. Subsidy on shrimp seed should be also given to encourage shrimp farmers to embrace and adopt quality shrimp seed for their farms

    Pengaruh Pelatihan Relaksasi Terhadap Penurunan Tingkat Kecemasan Melahirkan Anak Pertama

    Get PDF
    Tujuan penelitian untuk mengetahui pengaruh pelatihan relaksasi terhadap penurunan tingkat kecemasan melahirkan anak pertama. Hipotesis yang diajukan ada perbedaan kecemasan melahirkan anak pertama pada ibu hamil sebelum dan sesudah pelatihan relaksasi. Kecemasan melahirkan anak pertama pada ibu hamil sesudah pelatihan relaksasi lebih rendah dibandingkan sebelum pelatihan. Subjek penelitian sebanyak 10 pasien ibu hamil trisemester ke tiga, yang memeriksakan di Rumah Bersalin Aulia Boyolali. Metode pengumpulan data menggunakan skala kecemasan melahirkan anak pertama, intervensi me nggunakan pelatihan relaksasi. Data dioleh dengan teknik analisis non paramaterik wilcoxon. Hasil analisis pretest dengan posttest diperoleh nilai Z = -2,805; sig 0,005 (p< 0,01). Mean rank pretest sebesar 0,00 dan mean posttest sebesar 5,50. Hasil ini menunjukkan ada perbedaan kecemasan melahirkan anak pertama sebelum dan sesudah pelatihan. Artinya pelatihan relaksasi efektif untuk menurunkan kecemasan melahirkan anak pertama pada ibu kehamilan tri semester ketiga

    An ELPAT definition of the concept ‘Psychosocial’ in the context of Screening Living Organ Donors in Europe: A Concept Mapping approach

    Get PDF
    Introduction: Across Europe, transplant centers vary in the set of psychosocial screening criteria/guidelines used for the selection of eligible living donors. Our aim was to explore whether a common framework underlies this variation in screening criteria and, based on this framework, to develop a consensus on the essential elements of psychosocial screening of living liver and kidney donors. In order to do so, a research question was set out to define a conceptual framework of the concept ‘Psychosocial’ in the context of screening living organ donors in Europe. We formulated the following research question: Which psychosocial screening criteria are most commonly reported and considered as most important or effective in selecting eligible kidney and liver donors? Method: Concept mapping methodology was used to create a visual representation of the complex topic ‘Psychosocial’ in the context of screening living organ donors in Europe, in which underlying concepts, the relative importance of these concepts and the interplay between different concepts are organized. Initial psychosocial screening criteria (N=83) were derived from an extensive systematic literature review on guidelines, protocols and consensus statements on psychosocial screening practices, complemented by group brainstorm sessions. These criteria were then sorted and rated for their importance and effectiveness by 26 project participants. The data were analyzed using the Concept System Core© Software, which provided us with graphical depictions (concept maps) illustrating the view of project participants on these screening criteria. Pattern Matches and Go-Zones showed us the highlycommon, important and effective criteria. Results: The concept map procedure resulted in six clusters of psychosocial screening criteria: (1) Motivation and decision making (2) Personal resources (3) Psychopathology (4) Social resources (5) Ethical and Legal factors (6) Information and risk processing. Bivariate rating of these criteria revealed which important criteria are already frequently used for screening and which require more attention. Based on the cluster map and bivariate ratings we constructed a conceptual framework for non-medical risk factors that need to be considered when screening potential living organ donors. Conclusion: We provided a conceptual framework of psychosocial screening criteria which can serve as a practical recommendation for the psychosocial screening of potential living organ donors

    Simulation of Ammonia Production using HYSYS Software

    Get PDF
    Now-a-days, Because of cost and time consuming in the design of plants chemical engineer used simulators to simulate design and operation of chemical equipment and plant,  which spares a great deal of time and cash.Today, there are many number of the simulators are refreshed and utilized in the simulation of chemical equipment and plant such as ChemCad, ProII, UniSim……..etc. Among of these simulators, Aspen Hysys is the most utilized programming in all ventures because of aiding in two noteworthy fields (design &amp; operation). Simulation of ammonia synthesis process is done on Aspen Hysys V8.8 with steady state mode making some assumptions and using hypothetical reactors ammonia. By fluctuating the distinctive parameters in this simulation environment, the impact of these parameters in the generation rate of the procedure are watched. Keywords: Ammonia, Simulation, Aspen Hysys DOI: 10.7176/CPER/62-03 Publication date: January 31st 202

    Experimental verification of null steering by element positionperturbations

    Get PDF
    Null steering in an adaptive array is realized by element position perturbations. Small position perturbations are assumed, which is valid when the number of imposed nulls is small compared to the number of array elements. The null steering has been achieved for an eight-element monopole array over a ground plane. The array illumination function is used solely for pattern formation and can also be used for main beam steering. Single and double nulls are realized in the sidelobe region. The experimental results prove the validity of null steering by controlling the element position

    Null steering in phased arrays by controlling the element positions

    Get PDF
    Null steering methods usually involve costly and complicated amplitude and/or phase control systems. A technique is presented for null steering based on the element position perturbations. The technique frees the phase shifters to be used solely for steering the main beam toward the direction of the desired signal. It also removes the limitations of the other techniques by independently steering the main beam and the nulls to arbitrary independent directions. This technique is also capable of obtaining sidelobe cancellation and wideband signal rejectio

    Combined modal parameters-based index for damage identification in a beamlike structure: theoretical development and verification

    Get PDF
    A new index for detecting the damage severity in structural elements by combining modal parameters is proposed in this study. The index is based on the combined effect of both the natural frequencies and mode shapes when a change in stiffness of the structural element occurs. In order to demonstrate the significance and capability of this new algorithm, the magnitude of damage was calculated from a finite element model of a beam-like structure model and comparisons with previous algorithms were carried out. The new index called Combined Parameter Index (CPI) compares the factor of reduction in stiffness according to reduction in natural frequencies and also the factor of reduction in stiffness according to change in mode shape. Various damage levels starting from reduction in stiffness of 1 were adopted to validate the sensitivity of the new index to detect the damage severity at various deterioration levels. Mid-span and quarter-span damage positions were adopted to verify the capability of the new damage index to detect the damage severity at various locations. Moreover, damage in support condition was investigated in order to ascertain that the new damage index can also identify support damage cases. The results indicate that the new index has better ability and higher sensitivity to determine the severity of the damage due to stiffness changes in the element or support. In addition, the CPI exhibits sensitivity to detect lower level of damage occurring at earlier stage by having the ability to detect a damage of 1 reduction in the structural element stiffness or elastic bearing stiffness
    corecore