Studies on bacterial canker of tomato caused by Corynebacterium michiganense

In initial studies the symptoms of the disease bacterial canker of tomato caused by Corynebacterium michiganense were followed, and methods of inoculation were assessed. The morphological and physiological characters of c. michiganense isolations were studied and a modified selective medium was developed. Transmission of the disease by artificially-infected seeds varied depending on the conditions of the experiment. The number of diseased plants were less than the plants with 'resident phase' of C. michiganense. The disease is disseminated by infected debris and through commercial practices (handling diseased plants, using contaminated knives) but not with insects. The survival of c. michiganense in water varied but cells in high concentration, low temperature and anaerobic conditions survived more than one year. The pathogen survived at least 20 days on tomato leaves without symptoms; survival depended on relative humidity.The disease ratings were higher in succulent tissue of young plants, young parts of mature plants and in plants grown in light soils with excess fertiliser. The pathogen can cause hypersensitive reaction (HR) in tobacco leaves similar to one caused by pseudoraonads as the external and ultra-structural changes showed. The ultrastructural changes of tomato leaves infiltrated with saprophyte Pseudomonas aeruginosa, heterologous P. syringae and homologous c. michiganense were followed and compared. The development of foliage spots was followed by scanning electron microscopy. Studying the development of C. michiganense and other selected heterologous and saprophytic bacteria it was found that only C. michiganense multiplied from low inocula to high final populations. Some saprophytes could inhibit homologous and heterologous bacteria if they were inoculated earlier and in a ratio of 10:1 or higher. No host more sensitive than tomato was found. One infected seed in2000 or more could be detected by leaf infiltration techniques and a 10-4 pathogen cells ml-1 by using fluorescent substrate(3-0-methylfluorescein) in ELISA double antibody sandwich method.<p

The effect of inoculum concentration and time of application of various bactericides on the control of fire blight (Erwinia amylovora) under artificial inoculation

The efficacy of various bactericides for the control of fire blight (Erwinia amylovora) in pear flowers was tested. Bactericides were applied preventively one day before, or curatively one or three days after artificial inoculation with pathogen concentrations of 104, 105 and 107 cfu ml-1. The results indicated that a) preventive sprays were more effective than curative sprays; b) the effectiveness of curative sprays decreased progressively from the first to the third day; c) the infection was proportional to inoculum concentration, both in the water–sprayed (control) and in the bactericide–sprayed flowers. There was also significant interaction between bactericide and inoculum concentration. Best results were achieved with streptomycine (Agrept) at 0.5 g and 1 g l-1 H2O; oxolinic acid (S–0208) 1.5 g l-1 H2O; and flumequine (Firestop) 2 ml l-1 H2O. Kasugamycin (Kasumin), phosetyl–Al (Aliette) and copper hydroxide (Kocide) were less effective

Stochastic dynamic simulations of fast remagnetization processes: recent advances and applications

Numerical simulations of fast remagnetization processes using the stochastic dynamics are widely used to study various magnetic systems. In this paper we first address several crucial methodological problems of such simulations: (i) the influence of the finite-element discretization on the simulated dynamics, (ii) choice between Ito and Stratonovich stochastic calculi by the solution of micromagnetic stochastic equations of motion and (iii) non-trivial correlation properties of the random (thermal) field. Next we discuss several examples to demonstrate the great potential of the Langevin dynamics for studying fast remagnetization processes in technically relevant applications: we present numerical analysis of equilibrium magnon spectra in patterned structures, study thermal noise effects on the magnetization dynamics of nanoelements in pulsed fields and show some results for a remagnetization dynamics induced by a spin-polarized current.Comment: Invited paper submittedto JEMS'04 (Dresden, Germany

Exploring the Role of Metacognition in Measuring Students’ Critical Thinking and Knowledge in Mathematics: A Comparative Study of Regression and Neural Networks

This article discusses the importance of open-ended problems in mathematics education. The traditional approach to teaching mathematics focuses on the repetitive practice of well-defined problems with a clear solution, leaving little room for students to develop critical thinking and problem-solving skills. Open-ended problems, on the other hand, open-ended problems require students to apply their knowledge creatively and flexibly, often with multiple solutions. We herein present a case study of a high school mathematics class that incorporated open-ended problems into its curriculum. The students were given challenging problems requiring them to think beyond what they had learned in class and develop their problem-solving methods. The study results showed that students exposed to open-ended problems significantly improved their problem-solving abilities and ability to communicate and collaborate with their peers. The article also highlights the benefits of open-ended problems in preparing students for real-world situations. By encouraging students to develop their problem-solving strategies, they are better equipped to face the unpredictable challenges of the future. Additionally, open-ended problems promote a growth mindset and a love for learning, as students are encouraged to take risks and explore new ideas. Overall, the article argues that incorporating open-ended problems into mathematics education is a necessary step towards developing students’ critical thinking skills and preparing them for success in the real world

Factors Effecting Studies in the Department of Industrial Informatics of the Kavala Institute of Technology

Information regarding students’ and education institutes’ progress is a barometer for the overall prestige of the education system in Greece. Scientific community, the relative ministries and the society demand the evaluation of students and education institutes. Higher education studies are one of the most important level of education in Greece and compose important time in the lives of young scientists. A long deliberation took place during the last years regarding the time that is consuming for higher education and whether it should be unlimited or it should be limited to an upper limit. Recently, a rule of (2ν+1) for the upper limit of studies has been set by the Greek state. The pass-mark of 10 has been abolished and a deliberation for possible integration and abolishment of departments has started. In this paper, we study data regarding duration of studies in the department of Industrial Informatics of the Kavala Institute of Technology. The goal of this study is to extract important conclusions for the students’ progress and for their evaluation for the department. The final conclusions can become an important tool for the department, in order to make the necessary actions for its better function

Shape-dependent exchange bias effect in magnetic nanoparticles with core-shell morphology

We study the low-temperature isothermal magnetic hysteresis of cubical and spherical nanoparticles with ferromagnetic-core/antiferromagnetic-shell morphology, in order to elucidate the sensitivity of the exchange bias effect to the shape of the particles and the structural imperfections at the core-shell interface. We model the magnetic structure using a classical Heisenberg Hamiltonian with uniaxial anisotropy and simulate the hysteresis loop using the metropolis Monte Carlo algorithm. For nanoparticles with geometrically sharp interfaces, we find that cubes exhibit a higher coercivity and lower exchange bias field than spheres of the same size. With increasing interface roughness, the shape dependence of the characteristic fields gradually decays, and eventually, the distinction between cubical and spherical particles is lost for moderately rough interfaces. The sensitivity of the exchange bias field to the microstructural details of the interface is quantified by a scaling factor (b) relating the bias field to the net moment of the antiferromagnetic shell (Heb=bMAF+Ho). Cubical particles exhibit a lower sensitivity to the dispersed values of the net interfacial moment.This research was cofinanced by the European Social Fund and Greek national funds through the Research Funding Program ARCHIMEDES-III (MIS 383576)