This paper attempts to answer the usually neglected ethical questions of the interaction between tourism workers and participants in tourism movements and users of tourism services in general. Contact with numerous people in the work place, dynamic work with customers, continuous phone calls and stress due to constant responsibility, are just some of the conditions which tourism workers encounter on the daily basis and which sometimes make them ask themselves: Am I really able to do this job? Will their behaviour with each customer be ethical? Will they be able to hide from the customers their stress, nervousness and mental fatigue? Have all the employees in travel agencies attended the training courses in communication with customers, or does everything depend on their own decisions and home upbringing? Is it worth taking risk and putting agency`s reputation at stake? Which moral dilemmas do the tour guides encounter on the journeys? These are just some of the questions which will be put in the spotlight in this paper. The aim of this paper is to indicate the necessity to establish the codes of conduct for all professionals who are in direct contact with tourists.

The paper describes a procedure for identification of single machine infinite bus system. Mathematical model of synchronous generator is identified using data obtained from monitoring system. To determine the model parameters of the synchronous generator, a procedure based on Kalman filter was applied. The identified model of the synchronous generator can be used for parameter setting of the voltage controller and optimal parameter tuning of power system stabilizers.

We have examined the correlation between heat tolerance and small heat shock protein (sHSP) expression under heat stress conditions in potato (Solanum tuberosum l.). The relative heat tolerance of nine potato cultivars grown under greenhouse conditions was determined using the electrolyte leakage assay (el A), a standard quantitative assay for heat tolerance. Three cultivars differing in heat tolerance were selected and designated as heat-tolerant (' laura'), moderately sensitive (' liseta') and heat-sensitive ('Agria') genotypes. The expression of cytosolic HSP18 and chloroplast HSP21 was analyzed at the protein level in the leaves of selected cultivars, both ex vitro- and in vitro-grown , after heat stress or control treatment. Immunoblot analysis revealed heat-induced HSP18 and HSP21 expression in all examined genotypes. A similar pattern of examined sHSP expression was observed ex vitro and in vitro: heat-tolerant ' laura' accumulated higher levels of both HSP18 and HSP21 compared to heat-sensitive ' liseta' and ' Agria'. Our results indicate that elA combined with im- munoblot analysis of sHSP accumulation under HS conditions, might be considered as a reliable procedure in screening potato genotypes for heat tolerance. to our knowledge, this is the first study where sHSP expression between ex vitro- and in vitro-grown potato plants was compared.

In order to obtain multifunctional materials with good biocompatibility and antimicrobial effect, hydroxyapatite (HAp) doped with Zn2+ was synthesized by hydrothermal method. Powders with different content of zinc ions were synthesized and compared with undoped HAp to investigation of Zn2+ ion influence on the antimicrobial activity of HAp. Analyses of undoped and Zn2+-doped powders before and after thermal treatment at 1200oC were performed by SEM and XRD. Antimicrobial effects of powders were examined in relation to Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans in liquid medium. The results showed that the obtained powders have good antimicrobial activity, but higher antimicrobial activities of powders doped with Zn2+ were observed after annealing at 1200°C. For powders annealed at 1200°C in vitro biocompatibility tests MTT and DET with MRC-5 fibroblast cells in liquid medium were carried out. Based on MTT and DET tests it was shown that powders do not have a significant cytotoxic effect, which was confirmed by SEM analysis of MRC-5 fibroblast cells after theirs in vitro contact with powders. [Projekat Ministarstva nauke Republike Srbije, br. III 45019 and FP7-REGPOT-2009-1 NANOTECH FTM]

In this article the neurotoxic disorders appearing in patients poisoned with organophosphorus pesticides (OPs) are reviewed. OPs cause four important neurotoxic effects in humans: the cholinergic syndrome, the intermediate syndrome, organophosphate-induced delayed polyneuropathy and chronic organophosphateinduced neuropsychiatric disorder. Compared to the cholinergic syndrome, that causes millions of cases of poisoning with fatality of more than 15% each year, other disorders involve much smaller number of patients. This article is focused on neurotoxic disorders appearing after acute and chronic exposure to OPs with emphasis on clinical presentation, molecular mechanisms and possibilities of medical treatment.