Influence of different soaking times with selenium on growth, metabolic activities of wheat seedlings under low temperature stress

Low temperature (LT) is one of the most important factors limiting the growth, development and distribution of wheat plants in temperate regions. Selenium often acts as an antioxidant in plants and this study  hypothesize that selenium application can partly alleviate LT-induced oxidative stress and negative impacts of LT on wheat (Triticum aestivum L.) plant. Wheat seeds were soaked in aqueous solutions of selenium (5 mg Se L–1) for 5, 10 and 15 h. Then, the seeds were germinated at 3 or 5°C for 14 days and allowed to recover at 22°C for three days. The results show that low temperature stress inhibited the growth, chlorophylls, soluble sugars and antioxidant enzyme activities and increased oxidant production and membrane damage. Soaking the seeds in selenium solution for different times was feasible in enhancing the growth, chlorophylls,  anthocyanin, sugars, proline contents and enzymatic activities and decreased membrane damage by  enhancing antioxidant defense coupled with the appearance of novel protein bands. Se induced the lowering of respiratory potential measured as electron transport system (ETS) activity of mitochondria. However,  prolonged soaking in selenium (15 h) exerts toxic effects. These positive effects of Se are, however, dependent on the period of soaking.Key words: Selenium, cold stress, wheat seedlings, antioxidants, protein electrophoresis, respiratory potential

Application of Kalman filtering in computer relaying of power systems

Kalman-filter models for the optimal estimation of the post-fault currents and voltages for computer relaying purposes of power systems are presented. As a prerequisite for the Kalman-filtering implementation, the random description of the fault-induced noise signals was quantitatively studied. Empirical formulas that describe the random nature of the noise based on the probability of fault location and the frequency of occurrence of the different types of faults are given. These empirical formulas offer the possibility of developing other new techniques in computer relaying of power systems;Sensitivity of the Kalman filters to incorrect model parameters was studied through extensive simulation. A Kalman-filtering-based digital distance relay was designed to detect, classify, and locate faults in a high voltage transmission line in the shortest period of time;Comparison of the developed technique with four other algorithms demonstrated that the Kalman-filtering-based algorithm is superior to other techniques in the rate of convergence to the exact values, accuracy, and computer burden. Thus the Kalman-filtering approach appears to be especially well-suited to the power system protection problem

Coordination control of robot manipulators using flat outputs

Published ArticleThis paper focuses on the synchronizing control of multiple interconnected flexible robotic manipulators using differential flatness theory. The flatness theory has the advantage of simplifying trajectory tracking tasks of complex mechanical systems. Using this theory, we propose a new synchronization scheme whereby a formation of flatness based systems can be stabilized using their respective flat outputs. Using the flat outputs, we eliminate the need for cross coupling laws and communication protocols associated with such formations. The problem of robot coordination is reduced to synchronizing the flat outputs between the respective robot manipulators. Furthermore, the selection of the flat output used for the synchronizing control is not restricted as any system variable can be used. The problem of unmeasured states used in the control is also solved by reconstructing the missing states using flatness based interpolation. The proposed control law is less computationally intensive when compared to earlier reported work as integration of the differential equations is not required. Simulations using a formation of single link flexible joint robots are used to validate the proposed synchronizing control

Coordination control of robot manipulators using flat outputs

Published ArticleThis paper focuses on the synchronizing control of multiple interconnected flexible robotic manipulators using differential flatness theory. The flatness theory has the advantage of simplifying trajectory tracking tasks of complex mechanical systems. Using this theory, we propose a new synchronization scheme whereby a formation of flatness based systems can be stabilized using their respective flat outputs. Using the flat outputs, we eliminate the need for cross coupling laws and communication protocols associated with such formations. The problem of robot coordination is reduced to synchronizing the flat outputs between the respective robot manipulators. Furthermore, the selection of the flat output used for the synchronizing control is not restricted as any system variable can be used. The problem of unmeasured states used in the control is also solved by reconstructing the missing states using flatness based interpolation. The proposed control law is less computationally intensive when compared to earlier reported work as integration of the differential equations is not required. Simulations using a formation of single link flexible joint robots are used to validate the proposed synchronizing control

Physiological role of exogenous nitric oxide in improving performance, yield and some biochemical aspects of sunflower plant under zinc stress

The present study was undertaken to examine the possible roles of sodium nitroprusside in protection against oxidative damage due to zinc toxicity in sunflower plants. Physiochemical parameters in sunflower plants exposed to Zn2+ (100, 200 and 300 mg/kg soil) alone or combined with SNP were measured. The results showed that excess of Zn decreased plant growth, seed yield components and photosynthetic pigments content. On the other hand, Zn stress increased the level of non-enzymatic antioxidants (ascorbic acid and reduced glutathione) and enzymatic antioxidants (superoxide dismutase, ascrobate peroxidase and glutathione reductase), coupled with the appearance of novel protein bands. Furthermore, Zn stress increased Zn content in roots and shoots. The amounts of Zn in roots were higher than shoots. A marked increase in total saturated fatty acids accompanied by a decrease in total unsaturated fatty acids was observed. Exogenously application of SNP (20 μM) increased growth parameters, photosynthetic pigments content, ascorbic acid and glutathione contents, antioxidant enzyme activities and the quality of the oil in favour of the increase of unsaturated fatty acids. Moreover, SNP application increased Zn concentration in roots and inhibited Zn accumulation in shoots. Therefore, it is concluded that SNP treatment can help reduce Zn toxicity in sunflower plants

On twisted ordered monoid rings over quasi-Baer rings

In this paper we show that if M is an Ordered monoid then the twisted monoid ring R^T M is (left principally) quasi-Baer if and only if R is (left principally) quasi-Baer. Also if R is (left principally) quasi-Baer and G is an ordered group acting on R we give a necessary and sufficient condition for the crossed product R∗G to be (left principally) quasi-Baer

Genetic relationships among feed intake measures, feed conversion efficiency, and milk production traits in Holsteins using field recorded data

A total of 114,351 Holstein first lactation records collected by the Quebec Dairy Herd Analysis Service (DHAS-PATLQ) between September, 1979 and January, 1994 were used to study the effects of adjusting records for linear and quadratic effects of 90- and 305-d feed intake measures (total energy, total protein and total dry matter) on estimation of heritabilities of and genetic correlations among yield and composition traits. Genetic parameters of feed intake measures, relationships between feed intake and age and weight at calving, and feed conversion efficiency traits were also examined in a series of studies. A sire model fitted by REML estimated heritabilities of 305-d milk, fat and protein yields, fat and protein percents as .45 +/- .04, .48 +/- .04, .44 +/- .03, .92 +/- .06, and .88 +/- .05, respectively. Correction of 305-d records for differences among cows in feed intake levels reduced heritabilities of milk, fat and protein yields to .35 +/- .03, .52 +/- .04, and .38 +/- .03, respectively. Heritabilities of composition traits (fat and protein percents) remained unchanged. Genetic and phenotypic correlations for yield traits were also reduced (48--170%, and 16--51%, respectively) which may indicate that genetic associations between yield traits are less than what we believed them to be. Heritabilities of 305-d total energy, total protein, total DM intake, grain energy, grain protein, grain DM, base energy, base protein, and base DM were .30 +/- .03, .24 +/- .02, .35 +/- .03, .23 +/- .02, .23 +/- .02, .23 +/- .02, .31 +/- .03, .26 +/- .02, and .40 +/- .03, respectively. Genetic correlations between feed intake measures were very high; they were approaching unity in some cases. Therefore, any one of these feed intake measures can represent the others. A multi-trait REML analysis estimated heritabilities of age and weight at first calving as .11 +/- .01 and .37 +/- .03, respectively. Age at calving was negatively associated with yield traits and with total