Usporedba električkih nadomjesnih shema ljudskog zuba korištenih za mjerenje duljine korijenskog kanala

An accurate determination of the root canal length, which is the most critical procedure in the endodontic treatment of a tooth, is commonly performed nowadays by electronic apex locators which are based on electrical impedance measurements. In this paper tooth impedances were measured in vitro on extracted tooth in alginate material using HP 4284A LCR meter and a specially designed stalk with a micrometer for precise file positioning. In order to develop a more accurate measurement procedure human tooth was modeled by electrical equivalent circuit. Four new equivalent circuits comprising of resistors, capacitors and constant-phase elements were proposed in this paper and compared with four previously suggested circuits. Elements of equivalent circuits were determined by complex nonlinear least squares fitting using LEVM software. Different quality factors were defined to describe the fit quality of a certain equivalent circuit at each file position. The overall fitting efficiency in the region of file positions of interest was calculated as well. A detailed discussion was given on equivalent circuit parameters that can be used to measure the root canal length. Upon these results the most appropriate equivalent circuit was selected and a new measurement procedure was proposed.Točno određivanje duljine korijenskog kanala zuba, što je najkritičniji postupak u endodontskom tretmanu, se uobičajeno danas provodi elektroničkim detektorima apeksa koji se temelje na mjerenju električne impedancije. U ovoj studiji su impedancije zuba izmjerene in vitro na izvađenom zubu uronjenom u alginat. Korišten je HP 4284A LCR metar i posebno izrađeni stalak s mikrometrom za precizno pozicioniranje endodontskog instrumenta u kanalu. U svrhu razvoja točnije mjerne metode ljudski je zub modeliran električkom nadomjesnom shemom. Četiri nove nadomjesne sheme sastavljene od otpora, kapaciteta i elemenata s konstantnom fazom su predložene u ovom radu i uspoređene s četiri ranije predložene nadomjesne sheme. Elementi nadomjesnih shema su izračunati metodom kompleksnih nelinearnih najmanjih kvadrata korištenjem programa LEVM. Definirano je više faktora kvalitete kako bi se usporedilo svojstvo nadomjesnih shema da modeliraju izmjerenu impedanciju na pojedinim položajima endodontskog instrumenta u kanalu. Izračunati su i faktori kojima se uspoređuje sveukupna efikasnost nadomjesne sheme. Detaljno su objašnjeni parametri nadomjesnih shema koji se mogu koristiti za mjerenje duljine korijenskog kanala. Temeljem dobivenih rezultata odabrana je najpogodnija nadomjesna shema te je predložen novi mjerni postupak

Usporedba električkih nadomjesnih shema ljudskog zuba korištenih za mjerenje duljine korijenskog kanala

An accurate determination of the root canal length, which is the most critical procedure in the endodontic treatment of a tooth, is commonly performed nowadays by electronic apex locators which are based on electrical impedance measurements. In this paper tooth impedances were measured in vitro on extracted tooth in alginate material using HP 4284A LCR meter and a specially designed stalk with a micrometer for precise file positioning. In order to develop a more accurate measurement procedure human tooth was modeled by electrical equivalent circuit. Four new equivalent circuits comprising of resistors, capacitors and constant-phase elements were proposed in this paper and compared with four previously suggested circuits. Elements of equivalent circuits were determined by complex nonlinear least squares fitting using LEVM software. Different quality factors were defined to describe the fit quality of a certain equivalent circuit at each file position. The overall fitting efficiency in the region of file positions of interest was calculated as well. A detailed discussion was given on equivalent circuit parameters that can be used to measure the root canal length. Upon these results the most appropriate equivalent circuit was selected and a new measurement procedure was proposed.Točno određivanje duljine korijenskog kanala zuba, što je najkritičniji postupak u endodontskom tretmanu, se uobičajeno danas provodi elektroničkim detektorima apeksa koji se temelje na mjerenju električne impedancije. U ovoj studiji su impedancije zuba izmjerene in vitro na izvađenom zubu uronjenom u alginat. Korišten je HP 4284A LCR metar i posebno izrađeni stalak s mikrometrom za precizno pozicioniranje endodontskog instrumenta u kanalu. U svrhu razvoja točnije mjerne metode ljudski je zub modeliran električkom nadomjesnom shemom. Četiri nove nadomjesne sheme sastavljene od otpora, kapaciteta i elemenata s konstantnom fazom su predložene u ovom radu i uspoređene s četiri ranije predložene nadomjesne sheme. Elementi nadomjesnih shema su izračunati metodom kompleksnih nelinearnih najmanjih kvadrata korištenjem programa LEVM. Definirano je više faktora kvalitete kako bi se usporedilo svojstvo nadomjesnih shema da modeliraju izmjerenu impedanciju na pojedinim položajima endodontskog instrumenta u kanalu. Izračunati su i faktori kojima se uspoređuje sveukupna efikasnost nadomjesne sheme. Detaljno su objašnjeni parametri nadomjesnih shema koji se mogu koristiti za mjerenje duljine korijenskog kanala. Temeljem dobivenih rezultata odabrana je najpogodnija nadomjesna shema te je predložen novi mjerni postupak

Oblikovanje marketinškoga miksa na primjeru segmentacije tržišta autoškole

U današnje doba rijetko se može govoriti o tržištima na kojima nema konkurencije. Posebno u kontekstu proizvoda ili usluga široke potrošnje. Problem s kojim se suočavaju mnoge tvrtke ili ponuđači proizvoda ili usluga na tržištu je pitanje konkurentske prednosti; kako se nositi s visokom stopom konkurencije na određenom tržištu, kako uspješno poslovati i uspješno se razvijati. Ponuđači koji shvaćaju koncept segmentacije tržišta imaju priliku ponuditi veću vrijednost na tržištu i time pridobiti potrošače u odnosu na konkurenciju. U ovom radu, postupkom jednostavne segmentacije, korištenjem dviju najznačajnijih traženih koristi na tržištu autoškole, identificirana su četiri segmenta. Na temelju ustanovljenih razlika u traženim koristima razrađen je specifični marketinški miks za svaki pojedini segment čime se ukazuje na razlike u marketinškim pristupima nužnim za postizanje konkurentske prednosti

Oblikovanje marketinškoga miksa na primjeru segmentacije tržišta autoškole

U današnje doba rijetko se može govoriti o tržištima na kojima nema konkurencije. Posebno u kontekstu proizvoda ili usluga široke potrošnje. Problem s kojim se suočavaju mnoge tvrtke ili ponuđači proizvoda ili usluga na tržištu je pitanje konkurentske prednosti; kako se nositi s visokom stopom konkurencije na određenom tržištu, kako uspješno poslovati i uspješno se razvijati. Ponuđači koji shvaćaju koncept segmentacije tržišta imaju priliku ponuditi veću vrijednost na tržištu i time pridobiti potrošače u odnosu na konkurenciju. U ovom radu, postupkom jednostavne segmentacije, korištenjem dviju najznačajnijih traženih koristi na tržištu autoškole, identificirana su četiri segmenta. Na temelju ustanovljenih razlika u traženim koristima razrađen je specifični marketinški miks za svaki pojedini segment čime se ukazuje na razlike u marketinškim pristupima nužnim za postizanje konkurentske prednosti

Choice of Grout Curtain type of dam “Rečani” on Orizarska river – Kočani

In the frames of Preliminary design for choice of dam type for dam “Rečani” on river of Orizarska near Kočani, three types of embankment dams were elaborated. Based on the results from geological, hydrogeological, geotechnical investigations and recommendations of the geotechnical model, possible alternatives of the grout gallery and curtain were designed. Structural and geotechnical analyses were performed for each of the solutions. At the end, total costs of dam construction and grout works were calculated. Comparing all important factors, optimal design of the grout curtain was proposed. The selection of the optimal type of embankment dam and grouting curtain was also done with application of multi-criteria optimization, by applying of the method of compromise programming

Entrepreneurial Factors Influencing Recovery from Covid-19: A Country-Level Analysis

This study examines the impact of entrepreneurship ecosystem factors on the recovery of entrepreneurship from the COVID-19 pandemic and offers valuable insights to drive growth. By analyzing the Serbian dataset from the Global Entrepreneurship Monitor National Expert Survey in 2022, the study employs linear regression analysis to investigate the relationship between Entrepreneurial Framework Conditions and post-pandemic recovery. Data were collected through interviews with 40 experts representing the government, academia, and industry. The National Entrepreneurship Context Index score for Serbia\u27s entrepreneurial environment quality in 2022 is 4.6 which positions Serbia in the middle of the continuum of included country scores. The results of the analysis have shown that Market openness (β = .474; p < .01) and Achieving the UN Sustainable Economic Development Goals (β = .460; p < .01) have a direct positive impact on the recovery of entrepreneurs from the consequences of COVID-19. The limitations of the study are related to the demographics of the sample, self-reported data, geographic scope, focusing only on the Republic of Serbia, cross-sectional design that does not capture the dynamic and evolving nature of the recovery process. Given these limitations, future work could incorporate a more diverse sample to enhance the generalizability of the findings.This research provides important insights and policy recommendations to leverage entrepreneurial practices for economic recovery following the impact of the COVID-19 pandemic

Impact of drought and salt stress on seed germination and seedling growth of maize hybrids

Since maize is grown in climatically diverse regions and under different production conditions, the aim of our study was to investigate the effect of two common stress factors (drought and salinity), on seed germination, as well as on seedling root and shoot length of maize hybrids. The experiments were conducted in 2015, in the Laboratory for Seed Testing of the Institute of Field and Vegetable Crops from Novi Sad, Serbia, on seven maize hybrids from different maturity groups (from FAO 300 to FAO 700). For simulation of drought conditions we have used polyethylene glycol (PEG) 6000 (control and concentration of 1, 10, 16 and 23%). For study of salt stress, NaCl in concentration of 0.02, 0.07, 0.12, 0.17, 0.20 and 0.22 M has been used. The data obtained were processed by ANOVA. Duncan's Multiple Range Test was used to measure statistical differences between treatment methods and the control. In drought stress study, germination percentage started to decrease at the 0.1 MPa. Root and seedling length were less affected by PEG treatment. In salt stress study, a significant drop in germination was observed at the concentration of 0.20 M of NaCl

Uticaj suše na razvoj klijanaca kukuruza

Drought stress is one of the most important abiotic stresses influencing performance of crops. Certain stress-related conditions can appear and slow down germination, seedling development and in some cases cause loss of life durability of seed. Assuming that drought in the substrate affects corn seed performance, such conditions were simulated in this study in order to examine their effects on seed germination and length in seven corn hybrids. Polyethylene glycol (PEG) 6000 has been used in laboratory studies for simulation of drought conditions. Different osmotic potentials of PEG solutions were used (control; -0.1, -0.3, -0.6 and -0.9 MPa). Germination percentage decreased as osmotic potential increased at PEG solution.Suša je jedan od najvažnijih abiotskih stresova koji utiču na razvoj ratarskih kultura. Određeni uslovi koji su povezani s pojedinim stresovima mogu dovesti do usporavanja klijanja, razvoja ponika, a u nekim slučajevima i do gubitka životne sposobnosti semena. Pod pretpostavkom da nedostatak vode u supstratu utiče na karakteristike semena kukuruza, simulirani su uslovi suše u ovoj studiji sa ciljem da se ispita njihov uticaj na klijavost semena i razvoj ponika sedam hibrida kukuruza. Polietilen glikol (PEG) se koristi u laboratorijskim istraživanjima za simulaciju uslova suše. Koristili smo različite osmotske potencijale u rastvoru PEG-a (kontrola, -0,1, -0,3, -0,6 i -0,9 MPa). Procenat klijavosti je opadao sa smanjenjem osmotskog potencijala u rastvoru. Osetljivost korena i nadzemnog dela se povećava sa smanjenjem osmotskog potencijala. Na potencijalu od -0,6 i -0,9 MPa, nadzemni deo semena kukuruza nije se razvio