The Third Way

Apart from the traditional division "the teacher-centered" or "the student-centered education" the third option is, according to my mind and experience, more promising, more effective and more flexible. Namely, "the teacher-centered" education looks like an obsolete and worn-out concept, while "the student-centered" is mostly recognized as contemporary approach which must totally replace the old concept with predominant teacher's authority. The teacher-centered notion encapsulates teachers as the focal points of education. In other words teachers are organizers who rule the whole process of education, while students are mostly passive observers which active participation is strictly limited. On the other hand "the student-centered" education allegedly eliminates all major deficiencies of traditional authoritarian style fostering students' participation in all phases of education. The focus is shifted from teaching to learning (from teachers to students). The solution seems workable, efficient and self-evident - which is not the case. Instead of two extreme positions the third option emerges as more efficient; "the quality-centered education". The purpose of my paper is to prove the benefits of the "third approach" and define its major characteristics

Tehnički sistemi za kontrolu mikroklime u plastenicima

Plant production within a protected area presents the most intense way of agricultural production. Plant growing is intense year-round, with high yields and high quality products. The point of microclimate regulation in green house is to increase agriculture production within limited (protected) areas (spaces) with the least amount of production costs, by arranging a balanced ratio of many factors, first of all the climate, which influences the yields of the cultivated crops. Microclimate control in green houses presents an accountable, precise and complicated process, with respect to a number of factors that affect the climate within a protected space, which are interdependent, so the control could be successfully achieved only by applying the right technical systems and devices controlled by computers. The work shows new generations of control systems and devices with characteristics that are used to control microclimate of a green house.Biljna proizvodnja u zaštićenom prostoru predstavlja najintenzivniji oblik proizvodnje u poljoprivredi. Rast biljaka je intenzivan tokom cele godine, sa ostvarivanjem visokog prinosa i kvaliteta proizvoda . Svrha regulacije mikroklime u plastenicima je povećanje obima poljoprivredne proizvodnje na ograničenim (zaštićenim) površinama (prostorima) pri najmanjim proizvodnim troškovima, dovođenjem u skladan odnos mnogobrojnih faktora pre svega klime od kojih zavisi prinos gajenih kultura. Kontrola mikroklime u plastenicima predstavlja odgovoran, precizan i komplikovan proces, obzirom da ima više faktora koji utiču na klimu u zaštićenom prostoru, koji su uzajamno zavisni, pa se kontrola može uspešno postići jedino primenom odgovarajućih tehničkih sistema i uređaja kontrolisanih PC računarima. U radu su prikazane novije generacije kontrolnih sistema i uređaja sa karakteristikama koje se koriste u kontroli mikroklime plastenika

A small temperature rise may contribute towards the apparent induction by microwaves of heatshock gene expression in the nematode Caenorhabditis elegans

We have previously reported that low-intensity microwave exposure (0.75-1.0 GHz CW at 0.5 W; SAR 4-40 mW kg-1) can induce an apparently non-thermal heat-shock response in Caenorhabditis elegans worms carrying hsp16-1::reporter genes. Using matched copper TEM cells for both sham and exposed groups, we can detect only modest reporter induction in the latter (15-20% after 2.5 h at 26°C, rising to ~50% after 20 h). Traceable calibration of our copper TEM cell by the National Physical Laboratory (NPL) reveals significant power loss within the cell (8.5% at 1.0 GHz), accompanied by slight heating of exposed samples (~0.3°C at 1.0 W). Thus exposed samples are in fact slightly warmer (by ≤0.2°C at 0.5 W) than sham controls. Following NPL recommendations, our TEM cell design was modified with the aim of reducing both power loss and consequent heating. In the modified silver-plated cell, power loss is only 1.5% at 1.0 GHz, and sample warming is reduced to ~ 0.15°C at 1.0 W (i.e. ≤ 0.1°C at 0.5 W). Under sham:sham conditions, there is no difference in reporter expression between the modified silverplated TEM cell and an unmodified copper cell. However, worms exposed to microwaves (1.0 GHz and 0.5 W) in the silver-plated cell also show no detectable induction of reporter expression relative to sham controls in the copper cell. Thus the 20% “microwave induction” observed using two copper cells may be caused by a small temperature difference between sham and exposed conditions. In worms incubated for 2.5 h at 26.0, 26.2 and 27.0°C (with no microwave field), there is a consistent and significant increase in reporter expression between 26.0 and 26.2°C (by ~20% in each of 6 independent runs), but paradoxically expression levels at 27.0°C are similar to those seen at 26.0°C. This surprising result is in line with other evidence pointing towards complex regulation of hsp16-1 gene expression across the sub-heat-shock range of 25-27.5°C in C. elegans. We conclude that our original interpretation of a non-thermal effect of microwaves cannot be sustained; at least part of the explanation appears to be thermal

Aktivnost enzima katalaze i sadržaj organskih kiselina kod Hajdučke trave (Achillea millefolium) sa sanirane deponije „Žitkovac“ Rudarsko metalurško hemijskog kombinata „Trepča“

In this comparative study, the activity of enzyme catalase and total content of organic acids were determined in undergroung and above-ground plant parts of medicinal plant Achillea millefolium from tailing pond “Žitkovac” of Mining and Metallurgical Chemical Company „Trepča“ and from uncontaminated area near city of Niš. Catalase activity was measured using the gasometric method and the values obtained for this activity were expressed as ml of O2. The content of organic acids in the plant material was detrmined by modified titration method in the presence of indicator. An increased catalase activity on tailing pond, in comparison with uncontaminated habitat, is a result of stress that is caused by chemical changes in the soil on tailing pond representing good metabolic ways of detoxification, which belongs to the mechanisms of defence and acquiring resistance. An increased content of organic acids in samples on tailing pond is an efficient mechanism reducing the heavy metal uptake, binding them to complexes and allowing the plant growth at high level of contamination.U ovom komparativnom istraživanju određeni su aktivnost enzima katalaze i ukupan sadržaj organskih kiselina u podzemnim i nadzemnim delovima lekovite biljke hajdučka trava (Achillea millefolium) sa sanirane deponije „Žitkovac“ Rudarsko Metalurško Hemijskog Kombinata „Trepča“ i nezagađenog područja okoline Niša. Aktivnost katalaze je izmerena korišćenjem gasometrijske metode i izražena u ml kiseonika. Sadržaj organskih kiselina u bilјnom materijalu određen je modifikovanom metodom titracije u prisustvu indikatora. Uvećanje aktivnosti enzima katalaze kod uzoraka na deponiji u poređenju sa nezagađenim staništem je rezultat stresa uzrokovan hemijskim promenama u zemljištu i predstavlja metabolički vid razgradnje štetnih jedinjenja, odnosno detoksikacije, koja spada u kvalitetne mehanizme sticanja otpornosti, kao odgovor na izmenjene uslove u životnoj sredini. Povećan sadržaj organskih kiselina u uzorcima sa deponije je efikasan mehanizam, koji smanjuje unos teških metala u bilјku vezujući se za njih u komplekse i omogućava rast biljke pri visokom nivou kontaminacije

INFLUENCE OF CULTIVAR CHARACTERISTICS OF MUSCAT TABLE GRAPEVINE CULTIVARS (VITIS VINIFERA L.) ON GRAPE BRANDY COMPOSITION AND QUALITY

The goal of this paper has been to examine influence of a cultivar on the quality of a grape brandy produced from the muscat table cultivars: Demir kapija, Early muscat, Radmilovacki muskat, Banatski muskat, Muscat Hamburg, Smederevski muskat, Italy and Afuz-ali. In terms of the content of methyl alcohol as well as of the total evaporable ingredients, grape brandies made of the fermented grape mash of investigated cultivars meet the prescribed standards stipulated by the Rulebook on the Quality of Alcoholic Beverages

The Third Way

Apart from the traditional division "the teacher-centered" or "the student-centered education" the third option is, according to my mind and experience, more promising, more effective and more flexible. Namely, "the teacher-centered" education looks like an obsolete and worn-out concept, while "the student-centered" is mostly recognized as contemporary approach which must totally replace the old concept with predominant teacher's authority. The teacher-centered notion encapsulates teachers as the focal points of education. In other words teachers are organizers who rule the whole process of education, while students are mostly passive observers which active participation is strictly limited. On the other hand "the student-centered" education allegedly eliminates all major deficiencies of traditional authoritarian style fostering students' participation in all phases of education. The focus is shifted from teaching to learning (from teachers to students). The solution seems workable, efficient and self-evident - which is not the case. Instead of two extreme positions the third option emerges as more efficient; "the quality-centered education". The purpose of my paper is to prove the benefits of the "third approach" and define its major characteristics

Importance of background values in assessing the impact of heavy metals in river ecosystems: case study of Tisza River, Serbia

The main objective of this paper is to evaluate how a choice of different background values may affect assessing the anthropogenic heavy metal pollution in sediments from Tisza River (Serbia). The second objective of this paper is to underline significance of using geochemical background values when establishing quality criteria for sediment. Enrichment factor (EF), geoaccumulation index (I (geo)), pollution load index (PLI), and potential ecological risk index (PERI) were calculated using different background values. Three geochemical (average metal concentrations in continental crust, average metal concentrations in shale, and average metal concentrations in non-contaminated core sediment samples) and two statistical methods (delineation method and principal component analyses) were used for calculating background values. It can be concluded that obtained information of pollution status can be more dependent on the use of background values than the index/factor chosen. The best option to assess the potential river sediment contamination is to compare obtained concentrations of analyzed elements with concentrations of mineralogically and texturally comparable, uncontaminated core sediment samples. Geochemical background values should be taken into account when establishing quality criteria for soils, sediments, and waters. Due to complexity of the local lithology, it is recommended that environmental monitoring and assessment include selection of an appropriate background values to gain understanding of the geochemistry and potential source of pollution in a given environment

The inverted hysteresis loops and exchange bias effects in amorphous/nanocrystalline fe<inf>72</inf>cu<inf>1</inf>v<inf>4</inf>si<inf>15</inf>b<inf>8</inf> ribbons at room temperature

© 2020 Authors. Published by association for ETRAN Society. Тhe influence of thermally induced microstructural transformations on magnetic properties of Fe72Cu1V4Si15B8 ribbon with combined amorphous/nanocrystalline structure is presented. The experiments showed that thermally induced structural changes are in correlation with the appearance of magnetic hysteresis, i.e. with inverted hysteresis loops (IHL) and exchange bias (EB) effects. It was found that the ratio of surface to volume of a ribbon sample have an influence on hysteresis loop appearance. The inverted hysteresis loops were observed for the 1.5 mm wide and 55 μm thick alloy samples shorter than 10 mm, but for the samples longer than 10 mm hysteresis loops were normal. With an increase of annealing temperature, a shift of the hysteresis loops measured at room temperature was noticed. The highest positive exchange bias field Heb was observed for the sample annealed at 723 K, together with the lowest magnetic field at which the changes from inverted to normal hysteresis loop occurred. Annealing at the temperature of 823 K resulted in negative Heb