Hrčak - Portal of scientific journals of Croatia
Not a member yet
321498 research outputs found
Sort by
Influence of the Salix caprea Genotype and Leaf Characteristics on the Occurrence of Fungus Melampsora caprearum
No full textLeaf rust caused by Melampsora caprearum is one of the most important but understudied diseases of goat willow (Salix caprea). This research studied for the first time the effect of genotype and the morphology of goat willow leaves on the occurrence and abundance of Melampsora caprearum uredinia. The genotype showed a statistically significant impact on the occurrence and abundance of uredinia on goat willow leaves. The morphological characteristics of the leaves, leaf area, leaf circumference, and length and width of the leaves had a statistically significant effect on the occurrence of uredinia, while they did not impact the uredinia abundance on the leaves. On the same tree, leaves of larger dimensions showed greater resistance to the occurrence of infection symptoms. Based on leaf morphology, the results represent a realistic basis for selecting goat willow trees less susceptible to Melampsora caprearum. Measures that can be applied in goat willow habitats to regulate leaf dimensions and reduce damage from Melampsora caprearum are discussed
Observations on the marine benthic diatom Halamphora yundangensis W.W.Wu et al., a species originally described from China, in the Mediterranean Region
No full textDuring light and scanning electron microscope observations of marine benthic diatoms on various substrates in the eastern Adriatic Sea and the western Black Sea, we discovered a peculiarly structured amphoroid diatom species. The species was characterised by semi-elliptic to semi-lanceolate valves with distinctly protracted capitate to occasionally rostrate apices, a dorsal valve side crossed by transapical slits, a wide dorsal marginal ridge, biseriate dorsal striae internally, and usually lacking ventral striae externally, except for one or two poroids at the apices. Following a search in the literature, this taxon could only be identified as Halamphora yundangensis, a recently described species from the southeastern coasts of China. Here we present the first verified observation of this species in the Mediterranean Region. After thorough analyses of the observed populations in scanning electron microscopy and a literature overview, we provide an emended description of the species, and additional information enabling/justifying its separation from similar taxa occurring in the Mediterranean Region. Notes on the ecology and distribution of the species based on the new observations are also given
Optimizing an imperfect production system with varying production cost under selling price and advertising-driven demand
No full textThis study develops a production inventory model that accounts for imperfect production processes, acknowledging that a certain percentage of items produced are defective, reason being labor inefficiencies and machinery malfunctions. These defective items are identified and are segregated during the quality check and inspection phase and sold at a discounted price. The model incorporates economies of scale, whereby production costs decreases as productivity increases, and represents production costs as a diminishing function of productivity. Furthermore, the demand rate is modeled as dependent on advertising frequency and selling price, impacting significantly the product demand. The primary objective of this research is to determine the optimal advertising frequency, selling price, and the production cycle that maximize overall system profit. A numerical illustration is provided to validate the model, and a sensitivity analysis is conducted to assess the stability of the system. The findings reveal that increased demand reduces production time and raises pricing potential that leads to boosting of profits. Higher production rates improve efficiency and lower unit costs, while a higher defect rate and rising holding costs adversely impact profitability, which illustrates the importance of quality control and efficient inventory management. These insights highlight the model's practicality and innovation, offering valuable guidance for optimizing operations, managing costs, and achieving sustainable growth
HOW CAN I THRIVE AT WORK? THE INTERPLAY OF EMPLOYEES’ ENVIRONMENT, WORK CULTURE AND JOB-RELATED FACTORS
No full textThis study investigates how three organizational antecedents – environment, work culture, and job design – jointly shape employees’ thriving at work. We propose that these factors create a supportive ecosystem that fosters both vitality and learning. Using a survey of 316 employees in the ICT industry in North Macedonia, we conducted multiple linear regression analyses to assess the predictive power of environment, work culture, and job design on thriving at work. Results reveal that the environmental factors emerged as the strongest predictor, followed by job design and work culture. Altogether, these factors accounted for a substantial portion of the variability in thriving at work, underscoring their collective importance for employee well-being and development. From a practical standpoint, these findings suggest that enhancing physical, social, and structural job dimensions can substantially boost employees’ vitality and learning. For managers and human resource professionals, the insights encourage a holistic approach by integrating ergonomic practices, cultivating a positive organizational culture, and thoughtfully designing job roles to promote thriving in contemporary, often remote, work settings
Expressing three consecutive integers as sums of three cubes
No full textThis paper is concerned with the problem of expressing three consecutive integers as sums of three cubes. We give several parametric solutions of the problem. We also give some examples of five and seven consecutive integers that can all be expressed as sums of three cubes. We conclude the paper with an open problem regarding four or more consecutive integers expressible as sums of three cubes
Pruža li elektrokoagulacija učinkovito rješenje za uklanjanje mikroplastike iz sintetičke morske vode?
No full textMicroplastics (Mikroplastika
Indeks percepcije implementacije e-bankarstva (PI e-B) u Republici Kosovo
No full textUsing data collected from a random sample of 351 consumers and 60 employees of second-level banks, the Perception Index and its component indicators were assessed for the process of implementing e-banking services (PI e-B) in Kosovo. According to values of PI e-B currently, this process is classified at the “Moderate” level. Legislation, regulatory framework and perceptions of the benefits that banks and consumers realize from e-banking services are driving factors for the success of these services. The characteristics and peculiarities of the consumer, the level of economic and social development, the capacities and experiences in the use of information technology are factors that currently create barriers to increasing the effectiveness and territorial expansion of e-banking services in Kosovo. The PI e-B is an instrument that can be used by second-level banks to design policies and implement programs to increase the effectiveness and quality of e-banking services in Kosovo. In-depth statistical analysis for the construction of PI e-B as a multi-dimensional instrument, the values of which will be the result of weighting the values of its constituent indicators, are future directions of scientific research.Na temelju podataka prikupljenih iz slučajnog uzorka od 351 potrošača i 60 zaposlenika banaka druge razine, procijenjen je Indeks percepcije i njegovi sastavni pokazatelji za proces implementacije usluga e-bankarstva (PI e-B) u Republici Kosovo. Prema trenutačnim vrijednostima PI e-B, ovaj se proces klasificira na „umjerenoj” razini. Zakonodavni i regulatorni okvir te percepcija koristi koje banke i potrošači ostvaruju korištenjem usluga e-bankarstva predstavljaju ključne čimbenike uspješnosti ovih usluga. S druge strane, obilježja i specifičnosti potrošača, razina gospodarskog i društvenog razvoja te kapaciteti i iskustva u korištenju informacijske tehnologije trenutačno predstavljaju prepreke povećanju učinkovitosti i teritorijalnom širenju usluga e-bankarstva u Republici Kosovo. Indeks percepcije e-bankarstva (PI e-B) predstavlja instrument koji banke druge razine mogu koristiti pri oblikovanju politika i provedbi programa usmjerenih na povećanje učinkovitosti i kvalitete usluga e-bankarstva u Republici Kosovo. Buduća istraživanja trebala bi biti usmjerena na dublju statističku analizu konstrukcije PI e-B kao višedimenzionalnog instrumenta, čije će vrijednosti proizlaziti iz ponderiranja vrijednosti njegovih sastavnih pokazatelja
Diversity of aquatic mollusc communities of the river Cetina
No full textThe Balkan region is inhabited by hundreds of endemic freshwater molluscs, mainly small hydrobiids, and is considered a hotspot of global biodiversity. On the other hand, data about their distribution as well as data about distribution of more common and widespread molluscs have been still sparse and complete inventories of the mollusc communities of many areas are missing. The river Cetina is the largest river in the Adriatic part of Croatia. Aquatic non-marine molluscs of this river were studied in 2009, 2018-2022 and 2024. The quantity of distributional data were obtained thus the main objective of this study was to summarize and analyse recent distributional data on freshwater and brackish molluscs with special focus on endemic or threatened species. In total 35 aquatic molluscs were found at 26 sites at Cetina including its the biggest tributary Ruda. Mollusc communities at individual sites were usually composed of 5-15 species. Molluscs Theodoxus fluviatilis, Holandriana holandrii, Bithynia tentaculata, Radomaniola spp., Emmericia patula, Stagnicola fuscus, Physa fontinalis, Ancylus fluviatilis, Euglesa casertana and E. subtruncata were the most often recorded taxons found at least at half of studied sites. Notable is the occurrence of gastropods Dalmatinella simonae, Horatia klecakiana, Islamia sp. and several species of genus Radomaniola. No bivalves from the family Unionidae were found in the main stream of Cetina or Ruda. Numerous populations of non-native gastropod Potamopyrgus antipodarum in Cetina were found. The most serious impact is the change in the water regime caused by the construction of dams, which most likely had an impact on changes in the mollusc communities
Indirect estimation of serum enzymes reference intervals in adults using the reflimR and refineR algorithms
No full textIntroduction: Many clinical laboratories rely on manufacturer-provided reference intervals (RIs) because of logistical and financial constraints of direct RI estimation. Indirect estimation methods offer a practical alternative for deriving RIs from laboratory data. This study aimed to estimate RIs for eight serum enzymes using the R-based algorithm reflimR, and to compare them with refineR, manufacturer’s instructions for use (IFU), and direct methods.
Materials and methods: Data from adult outpatients tested between January 2021 and May 2022 were retrospectively analyzed for alkaline phosphatase (ALP), alanine aminotransferase (ALT), amylase, aspartate aminotransferase (AST), creatine kinase (CK), gamma-glutamyl transferase (GGT), lactate dehydrogenase and lipase. Reference intervals were estimated using reflimR and refineR, and compared with IFU and direct RIs. Overlap between lower and upper limits was evaluated using a color-coded scheme. Data distribution was tested with Shapiro–Wilk; and Mann–Whitney U and Spearman’s correlation tests were used for group comparisons and correlations.
Results: Sex-specific RIs were required for ALP, ALT, AST, CK and GGT. ReflimR generally produced wider intervals than refineR. Agreement of reflimR with refineR, parametric, and IFU-based RIs was 88.5%, 72.7%, and 62.5%, respectively. The lowest agreement was observed with the non-parametric method (55.0%).
Conclusions: ReflimR provides a practical approach for indirect RIs estimation from routine data. Its performance was comparable to refineR and parametric methods, supporting its use for verifying or updating local RIs, especially where population-specific RIs are unavailable. To our knowledge, this is the first study to apply reflimR to the Turkish population and directly compare its performance with refineR and IFUs