The article presents findings of a two-year systematic study of stable isotope content in two karst groundwater resources in Primorsko-goranska county (Croatia): the Martinšćica wells (MWs) and the ...Dobrica spring (DBC). The temporal and spatial variation of hydrogen and oxygen isotopes is commonly studied in conjunction with hydrogeological conditions such as groundwater dynamics and discharge conditions. However, since this information was incomplete, we were forced to work with limited data and rely on analyses of stable isotope monitoring results. The obtained results show that winter precipitation is the most common recharge source for the systems, and the average residence time of water in the subsurface is less than a year. Furthermore, the MWs system is a typical dual-porosity system with dominant base flow. The results of the nonparametric regression analysis show that the possibility of seawater intrusion into the spring affecting DBC isotope content cannot be ruled out. We believe that the results presented in the paper demonstrate that when combined with statistical analyses, environmental stable isotopes are a powerful tool for gaining insights in karst hydrogeology.
The Gacka River basin aquifer is a highly-developed karst system, located in the Croatian Dinarides. It is mostly composed of permeable Jurassic and Cretaceous carbonate rocks, and clastic ...sedimentary rocks of Paleogene age. Gacka River provides high quality water for the town of Otočac and several villages; together with the neighboring Lika River, the water is used for the Hydroelectric Power Plant at Senj on the coast. About 10 perennial and over 20 seasonal springs are located at 450 to 460ma.s.l. (above sea level). Three major springs (Pećina, Majerovo and Tonkovića) provide 57% of the mean annual river flow. Similarities between the average groundwater temperatures as well as between the average specific electrical conductivity values (9.0°C-328μS/cm, 9.6°C-350μS/cm and 8.9°C-312μS/cm) of the springs imply that they are fed from aquifers with similar mean residence times (MRTs). The mean δ18O contents of Majerovo, Tonkovića, and Pećina are around −10.1‰, −9.2‰ and −8.9‰, respectively, revealing differences in the mean recharge area elevations. Compared to the temporal amplitude of the18O signal of precipitation, the 18O signal variations of the springs are substantially attenuated because the recharges occurring at different times are well mixed within the aquifers. This indicates MRTs of more than just a few years. The average tritium contents of Pećina, Majerovo and Tonkovića are 5.48TU, 6.13TU and 6.17TU, respectively. Serially connected exponential-plug type unsteady lumped-parameter models run on an annual time scale resulted in rather satisfactory matches between the observed and calculated tritium contents for all studied springs. The models revealed similar MRTs (and corresponding reservoir volumes) for Pećina, Tonkovića and Majerovo of 12years (470Mm3), 12years (1190Mm3), and 12.2years (1210Mm3), respectively. Plug flow conditions dominate in about 90% of the total aquifer volumes.
•The Gacka River karst aquifer is part of the strategic water resource of Croatia.•The discharge of springs indicates a long mean residence times of ground water.•Tritium-based models yield MRTs of ca. 12years and a large reservoir volume.•Areal recharge mainly in the cold season; plug flow conditions are dominant.
Aim: To inform about the results of isotopic analyses of karstic springs, Rječina Spring and Zvir, that ensure potable water for more than 200,000 people in Rijeka County (Croatia)
Methods: Specific ...activities of selected radionuclides were determined by high resolution gamma spectrometric analysis and radiochemical separation method. Values of hydrogen and stable isotope contents were determined by water equilibration method on isotope ratio mass spectrometer in conjunction with dual inlet and equilibration peripheral unit.
Results: Anthropogenic radionuclides were detected in trace amounts. The results of the analysis show that the calculated yearly dose introduced to an adult human consuming 2 liters of water per day is approximately 20 mSv. Stable isotopes content of the spring waters indicate a dominant recharge of the analyzed hydrological system by winter precipitation. Different isotopic variations of spring water as a consequence of sudden precipitation inputs in summer and autumn indicate that water discharged at Rječina Spring mainly originates from a big water reservoir situated in the wide mountain region in the hinterland of the spring.
Conclusion: The examined water is potable and radiologically safe. Stable isotope variations of the spring water show a fast reaction to sudden precipitation inputs, confirming the ecological vulnerability of karstic springs. In light of recent heavy precipitation and flooding in different parts of Croatia, a more systematic research on isotopic water composition should be encouraged.
Cilj: Cilj rada je predstaviti rezultate ispitivanja studentskih stavova o fizici i njihove povezanosti s usvajanjem koncepata u fizici. Ispitanici i metode: U istraživanju je sudjelovalo 89 ...studenata prve godine Preddiplomskog stručnog studija Fizioterapija, Fakulteta zdravstvenih studija Sveučilišta u Rijeci. Ovom istraživanju, prethodilo je ispitivanje učenika sedmih i osmih razreda jedne riječke osnovne škole (N = 92). Upitnik je sadržavao tvrdnje kojima su izražavani stavovi ispitanika studenata o fizici. Drugi dio upitnika činile su tvrdnje među kojima su bile i česte miskoncepcije u fizici. Miskoncepcije smo podijelili na one koje nastaju zbog jezičnog miješanja pojmova iz svakodnevnog života i znanosti, one koje proizlaze iz korištenja neispravnih pretpostavki za objašnjenje svakodnevnog iskustva te one koje se temelje na nerazumijevanju znanstvenih pojmova i koncepata. Rezultati: Studenti u najvećoj mjeri imaju neutralan stav prema fizici. Postoji statistički značajna razlika u zastupljenosti miskoncepcija prema uzroku njihova nastanaka (Hi-kvadrat; P < 0,001). Najzastupljenijima su se pokazale miskoncepcije nastale poistovjećivanjem izraza iz svakodnevnog života i znanosti, tzv. žargonske miskoncepcije (58 % slučajeva). Utjecaj studentskih stavova na učestalost miskoncepcija pokazao se statistički značajnim za stavove koji ukazuju na to da su ispitanici više usmjereni na memoriranje gradiva i kvantitativne manipulacije nego na uspješno usvajanje znanstvenih pojmova i koncepata. Zaključci: Primjena napredne tehnologije u terapiji i dijagnostici u okviru medicinske skrbi ukazuje na sve veću potrebu za znanjem iz fizike kod studenata zdravstvenih i medicinskih studija. Studenti shvaćaju važnost fizike u svojem obrazovanju i većinom ne iskazuju negativan stav prema fizici. Određene vrste miskoncepcija zadržavaju se tijekom čitavog obrazovnog procesa. Zato treba sprječavati nastanak neznanstvenih koncepata, odnosno ako oni već postoje, treba ih što ranije detektirati i aktivno raditi na njihovom uklanjanju.
Objective: The aim of the paper is to present the results of the study of students’ attitudes towards physics and their relationship with the acquisition of concepts in physics. Subjects and Methods: Eighty-nine students of the first year of undergraduate studies in physiotherapy at the Faculty of Health Studies, University of Rijeka, participated in the study. This study was preceded by a survey of seventh and eighth grade students of an elementary school in Rijeka (N=92). The questionnaire contained statements expressing the attitude of the surveyed students towards physics. The second part of the questionnaire consisted of statements that included common misconceptions in physics. We divided the misconceptions into those that arise from the linguistic mixing of terms from everyday life and science, those that result from the use of incorrect assumptions to explain everyday experiences, and those that are based on a misunderstanding of scientific terms and concepts. Results: Students have predominantly neutral attitudes toward physics. There is a statistically significant difference in the prevalence of misconceptions according to the cause of their occurrence (chi-square; P<0.001). The most prevalent misconceptions were those arising from the identification of expressions used in everyday life and science, the so-called jargon misconceptions (58% of cases). The influence of student attitudes on the frequency of misconceptions proved statistically significant for attitudes indicating that respondents focus more on memorising data and quantitative manipulations than on successfully acquiring scientific terms and concepts. Conclusions: The application of advanced technologies in therapy and diagnostics in the context of medical care indicates an increasing need for physics knowledge among students in health and medical programmes. Students are aware of the importance of physics to their education and, for the most part, do not have negative attitudes toward physics. Certain types of misconceptions persist throughout the educational process. Therefore, the emergence of unscientific concepts should be prevented, but if they already exist, they should be identified as early as possible and active efforts should be made to eliminate them.
Introduction: The Republic of Croatia (HR) has significantly invested in monitoring the quality of inland bathing areas during the past 10 years. The aim of this paper was to analyze the results ...obtained during the 2014-2019 period and to compare them with the Region (non-European Union EU countries neighboring Croatia) and EU. Moreover, bathing water quality data at two bathing areas of Zagreb (lakes Jarun and Bundek) were processed in more detail.Methods: The quality of inland bathing areas in the HR is monitored in five rivers and five lakes in nine Croatian counties; 19 of the 35 monitored sites are located in Zagreb County. Escherichia coli (EC) was determined by EN ISO 9308-3: 1998, while intestinal enterococci (ENT) were defined by EN ISO 7899-2: 2000. Statistical processing of the results was performed using the Microsoft Excel Statistical Package (Redmond, USA) and Statistica 13.5. (Stat.Sof.Inc., Tulsa, USA); the significance level was set to p < 0.05.Results: During the study period, the worst Croatian inland water quality was recorded in 2019 (excellent quality for only 25.9% of the bathing areas), while the best quality was recorded in 2015 (excellent quality in 57.1%). On average (2014-2019), the share of bathing areas with excellent quality in Croatia was 46.3% (i.e., under the EU average of 85.3%); with no poor locations (EU average was nearly 2%). A significant positive correlation was found between fecal indicators (EC&ENT) and the amount of precipitation, while a negative correlation with water and air temperature in lakes.Conclusions: The quality of Croatian inland bathing areas is significantly lower than the European average, while EU water quality is improving. Regarding the countries bordering Croatia, Italy, Slovenia, and Hungary have achieved better results, while Montenegro, Serbia, and Bosnia and Herzegovina are still in the process of developing the monitoring of the bathing water quality.
U fizici, plazma je ioniziran, kvazineutralan plin za koji se često kaže da je četvrto stanje materije. Dugo vremena se plazma u medicini koristila zbog svojih termalnih svojstava, primjerice za ...sterilizaciju kirurškog i medicinskog pribora te za rezanje i kauterizaciju tkiva. Generiranjem hladne plazme u atmosferskim uvjetima započelo je novo razdoblje u primjeni plazme u biomedicini. Plazma medicina novo je interdisciplinarno znanstveno područje koje kombinira spoznaje fizike plazme s biomedicinskim i kliničkim znanostima. Hladna atmosferska plazma emitira elektromagnetno zračenje te se sastoji od mnoštva nabijenih i nenabijenih čestica, među kojima su najznačajnije reaktivne kisikove i dušikove vrste. Smatra se da su upravo reaktivne kisikove vrste najvažnije za biološke učinke plazme kao što su inaktivacija mikroorganizama i biofilmova. U dermatologiji se pokazalo da hladna atmosferska plazma pozitivno utječe na zacjeljivanje kroničnih rana. Prvi instrumenti za primjenu hladne plazme na ljudima već su i komercijalno dostupni. Primjena hladne plazme ima velik potencijal za primjenu u onkologiji, ali i u stomatologiji. Mnogobrojne studije dale su vrlo obećavajuće rezultate za primjenu hladne plazme u medicini, no treba imati na umu da mehanizmi međudjelovanja plazme s biološkim tkivom još uvijek nisu u potpunosti razjašnjeni, da nema dogovorom prihvaćene definicije doze koju plazma predaje materiji, da još uvijek nema standardiziranih instrumenata za generiranje i karakterizaciju plazme te da za pravu procjenu potencijala primjene atmosferske plazme u medicini i stomatologiji nedostaje više detaljnih in vivo studija.
We analyze a panel of 147 countries over a 21-year period. We used the Generalized Method of Moments First Differences panel estimation method and found that there is a statistically significant ...positive association between terrestrial protected areas and protected species. There is strong evidence of a positive statistical relationship between the Human Development Index and protected species under the condition of efficient nitrogen use as an instrumental variable. We support the revision of the Environmental Kuznets Curve hypothesis by claiming that in the 21st century it need not be strictly U-shaped, but that a rise in environmental protection measures is present across the board. The final contribution of the paper is the idea that protecting the habitat of endangered species is commensurate with increasing human welfare through income, health and education.
Atmospheric pressure plasma jets (APPJs) are a promising tool in medicine with extensive possibilities of utilization. For a safe and therapeutically effective application of APPJs, it is necessary ...to know in detail the physical processes in plasma as well as possible hazards. In this paper, we focus on plasma thermal energy transferred to the substrate, i.e. to a passive thermal probe acting as substrate dummy. Specifically, we examined the dependence of transferred energy on the distance from the plasma source outlet, on the gas flow rate, and on the length of the visible plasma plume. The plasma plume is the plasma carried by the gas flow from the outlet of the source into the ambient air. The results show the distance between the plasma-generating device and the substrate to be the most important determinant of the transferred thermal energy, among the three examined variables. Most importantly for the end-user, the results also show this relation to be non-linear. To describe this relation, we chose a model based on a Boltzmann type of sigmoid function. Based on the results of our modelling and visual inspection of the plasma, we provide sort of a user guide for the adjustment of a suitable energy flux on the (bio) substrate.
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Aim To develop a new method of health-economic analysis based on a marginal approach. Methods We tested the research hypothesis that a detailed comparative a priori incremental cost-effectiveness ...analysis provides the necessary input for budget impact analysis about the proper order of introduction of new therapies, and thus maximizes the cost-effectiveness bounded by the total budget constraint. For the analysis we chose a combination therapy for the treatment of hepatitis C virus (HCV) genotype 1 (GT1) infection, which was approved by the European Medicine Agency in 2015. We used the incremental cost-effective approach to assess the increase in the percentage of patients achieving sustained virological response (SVR) and the expenditure per additional SVR modulated by the new therapy's market entrance dynamics. Patient subpopulations were differentiated by their response to previous treatment, presence of cirrhosis, and HCV GT1 subtype. Final parameters were estimated by Monte Carlo simulations. Results The new combination therapy had high efficacy, shorter duration, and was better tolerated than alternative interventions. The research hypothesis was confirmed: gradual introduction of the new therapy on the market, based on a priori incremental cost-effectiveness analysis, would result in average increase in successfully treated patients by 20%-40%, while additional costs would approximately be between 8%-40%, ie, 21 000-52 000 euro per additional patient achieving SVR. Conclusion We showed the new combination therapy to be cost-effective for certain patient subpopulations, especially for experienced cirrhotic HCV GT1 patients. Results of the analysis are in agreement with the latest recommendations for HCV patients' treatment in Croatia. This economic evaluation could serve as a starting point for negotiations between pharmaceutical industry and insurance companies.
We tested the validity of the traditional hypothesis of a causal effect between rainfall occurrence, groundwater discharging into the sea, and marine microbial contamination. For groundwater ...characterization, we used the \(^18 O\) isotope. This stable isotope, together with 2 H, proved to be a useful physical, naturally occurring tracer primarily due to its abundance variations at different stages of water cycle. Test locations include Bakar Bay and selected adjacent Rijeka city beaches (Croatia). To test for statistical associations, we used the Panel Data Pairwise Granger Causality test. At examined locations, we found statistically significant relationships between the amount of rainfall and the abundance of \(^18 O\) isotope in groundwater, as well as relationships between the abundance of \(^18 O\) isotope in groundwater and faecal bacteria concentrations. Accordingly, \(^18 O\) isotope, when used as an indicator for the functioning of karstic groundwater systems, may also be used as the predictor of faecal contamination of bathing waters in associated karst littoral areas. We believe this physical method could be a valuable addition to present methods of predicting microbiological contamination and economic allocation of stock and flow pollutants in scarce common pool resources as fresh water basins, springs and beaches.
Testirali smo hipotezu o statističkoj povezanosti između kiše, podzemnih voda koje utječu u more i mikrobiološkog onečišćenja mora. Kao varijablu koja opisuje podzemne vode odabrali smo stabilni izotop \(^18 O\). Stabilni izotop \(^18 O\) vode je okolišni obilježivač koji se često korisiti u hidrologiji, osobito u krškim područjima kakav je obalni pojas Jadranskog mora. Testiranje je provedeno na lokacijama u Bakarskom zaljevu i odabranim plažama u gradu Rijeci. Panel analizom “Granger kauzalnosti” utvrdili smo postojanje statistički značajne povezanosti između količine oborina i izdašnosti \(^18 O\) izotopa u podzemnim vodama, kao i statistički značajnu povezanost između izdašnosti \(^18 O\) u podzemnim vodama i koncentracije fekalnih bakterija u moru. U skladu s dobivenim rezultatima možemo zaključti da se stabilni izotop \(^18 O\), u slučaju kada se koristi kao obilježivač za proučavanje krških podzemnih voda, također može koristiti i kao prediktorska varijabla fekalnog onečišćenja mora u koje se te podzemne vode ulijevaju. Pretpostavljamo da bi ova fizikalna metoda mogla biti vrijedan dodatak metodama predviđanja mikrobioloških zagađenja i ekonomske alokacije oskudnih zaliha zajedničkih prirodnih resursa kao što su vodonosnici, izvori pitke vode i plaže.
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