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Geometrijski randomizirani algoritmi
No full textOvaj rad istražuje ključne aspekte geometrijskih algoritama i struktura, s posebnim naglaskom na randomizaciju, dekompoziciju prostora i navigacijske strategije te koristi algoritama u stvarnom životu. U uvodnim dijelovima obrađuje se probleme konstrukcija konveksnih ljuski u ravnini i prostoru. Uz to definira se i koncept dualnosti s pomoću kojeg dobivamo "duale" prije opisanih problema. Za dane algoritme analiziramo njihovu očekivanu vremensku složenost. Nadalje, analiziraju se različite tehnike dekompozicije prostora uz korist randomizacije. Prvo definiramo Voronojieve dijagrame i Delaunayjeve triangulacije te dajemo randomizirani algoritam za njihovu konstrukciju koji je usko vezan s problemom konstrukcije konveksne ljuske u tri dimenzije. Uz to dajemo još jedan algoritam za slučaj triangulacije konveksnog poligona. Nakon toga dajemo randomizirane algoritme za konstrukcije trapezoidne dekompozicije i binarnih particija ravnine. Sve dekompozicije imaju široku primjenu u računalnoj geometriji s naglaskom na računalnoj grafici. U zadnjem poglavlju poseban fokus stavljen je na algoritme vezane uz Delaunayjeve triangulacije, gdje se razmatraju različite strategije usmjeravanja, uključujući razne jednostavne determinističke algoritme s naglaskom na pohlepnim algoritmima, te njihova proširenja kroz randomizaciju. Za sve algoritme mjerimo koliko su dobri definirajući im -kompetitivnost. Ispituje se ograničenja determinističkih algoritama bez memorije i analiziraju njihovi negativni rezultati u specifičnim scenarijima. Na kraju poglavlja dajemo algoritam koji je -kompetitivan. Završni dio sadrži kratku raspravu o algoritmima. Rad sintetizira teorijska saznanja i praktične primjene u području računalne geometrije, te pokazuje da su u nekim slučajevima jednostavniji algoritmi bolji za rješavanje određenih problema.This paper explores key aspects of geometric algorithms and structures, with a special focus on randomization, space decomposition, and navigation strategies, as well as the practical applications of these algorithms in real life. In the introductory sections, the paper addresses the problems of constructing convex hulls in the plane and in space. The concept of duality is also defined, allowing us to obtain the ”duals” of the previously described problems. The expected time complexity of these algorithms is analyzed. Further, various space decomposition techniques utilizing randomization are explored. First, Voronoi diagrams and Delaunay triangulations are defined, and a randomized algorithm for their construction is presented, which is closely related to the problem of constructing a convex hull in three dimensions. Additionally, another algorithm for the triangulation of convex polygons is provided. The paper then presents randomized algorithms for the construction of trapezoidal decompositions and binary partitions of the plane. All these decompositions have broad applications in computational geometry, with an emphasis on computer graphics. The final chapter focuses on algorithms related to Delaunay triangulations, where different routing strategies are examined, including various simple deterministic algorithms with an emphasis on greedy algorithms, and their extensions through randomization. For all algorithms, their performance is evaluated by defining their c-competitiveness. The limitations of memoryless deterministic algorithms are examined, and their poor results in specific scenarios are analyzed. The chapter concludes with the presentation of the only c-competitive algorithm. The concluding section includes a brief discussion on the algorithms. This paper synthesizes theoretical insights and practical applications in the field of computational geometry, showing that in some cases, simpler algorithms are more effective for solving certain problems
Pamukkale as a geological and geochemical phenomenon
No full textCilj ovoga rada bilo je određivanje mineraloških značajki uzorka travertina prikupljenog na jednom od bazena Pamukkale, u Turskoj. Provedene su metode: kalcimetrija, kompleksometrija i rendgenska difrakcijska analiza. Navedenim analizama utvrdilo se da se radi o nisko magnezijskom kalcitu. Udio karbonatne komponente je gotovo stopostotni, a od toga je 2,49 % bio udio MgCO3. Travertin je značajan i u sektoru građevinarstva. Upravo zbog svoje niske tvrdoće, lako ga je obrađivati.The aim of this work was to determine the mineralogical characteristics of a travertine sample collected from one of the basins of Pamukkale, in Turkey. The following analytical methods were performed: calcimetry, complexometry and X-ray diffraction analysis. The beforementioned analyses determined that the sample is low-magnesium calcite. The share of the carbonate component is almost 100 %, of which 2.49 % was the share of MgCO3.Travertine is also significant in the construction sector. Precisely because of its low hardness, it is easy to process
Veliki jezični modeli za generiranje ugradbenih vektora
No full textVeliki jezični modeli donijeli su značajan napredak u području obrade prirodnog jezika, omogućujući dublje razumijevanje teksta putem ugradbenih vektora.
U ovom radu analizirali smo arhitekturu transformera, koja predstavlja temelj velikih jezičnih modela i ima ključnu ulogu u suvremenim tehnološkim rješenjima obrade jezika. Istražili smo metode pretraživanja teksta koristeći ugradbene vektore, kao i klasične pristupe poput BM25. Također smo razmatrali kako se ugradbeni vektori u kombinaciji s jezičnim modelima mogu koristiti unutar sustava RAG, čime se značajno proširuje raspon znanja i povećava primjenjivost velikih jezičnih modela.
Naš doprinos obuhvaća razvoj ugradbenog modela , temeljenog na arhitekturi Gemma, koji generira ugradbene vektore prilagođene pretraživanju teksta na hrvatskom jeziku. Eksperimentalni rezultati pokazali su da ovaj model na našem skupu podataka postiže nešto bolje rezultate u usporedbi s ostalim metodama. Kao završni korak, implementirali smo sustav RAG koristeći razvijeni model.Large language models have brought significant advancements in the field of natural language processing, enabling a deeper understanding of text through embedding vectors.
In this study, we analyzed the transformer architecture, which serves as the foundation of large language models and plays a crucial role in modern language processing technologies. We explored text retrieval methods using embedding vectors, as well as classical approaches such as BM25. Additionally, we examined how embedding vectors, in combination with language models, can be utilized within the RAG system, significantly expanding the knowledge scope and increasing the applicability of large language models.
Our contribution includes the development of the embedding model , based on the Gemma architecture, which generates embedding vectors tailored for text retrieval in the Croatian language. Experimental results have shown that this model achieves slightly better performance on our dataset compared to other methods. Finally, we implemented a RAG system using the developed model
A critical review of regional cooperation of Southeast Europe
No full textUsprkos svojim novim političkim, ekonomskim i socijalnim značajkama, nastalima nakon rušenja Berlinskog zida i stvaranja novog svjetskog poretka, Jugoistočna Europa se još uvijek smatra jednim od najnestabilnijih područja Europe. Pokretane su brojne inicijative od strane međunarodne zajednice s ciljem stabilizacije regije Jugoistočne Europe i očuvanja mira u istoj. Regija Jugoistočne Europe je prostor izuzetno bogat poviješću, različitim vjerama, kulturama i običajima, ali i nizom otvorenih pitanja koja se tiču suradnje među državama na ovom području. Regionalna suradnja u Jugoistočnoj Europi ostvaruje se kroz brojne inicijative koje potiču ekonomsku, političku i sigurnosnu integraciju, ali njihova učinkovitost ovisi o političkoj volji i stabilnosti država. Iako su neke zemlje aktivnije uključene u procese suradnje, razlike u prioritetima i institucionalnim kapacitetima utječu na njihov stvarni uspjeh. Cilj ovog rada je na temelju pregleda znanstvenih i stručnih radova te internetskih izvora, analizirati i usporediti obilježja i učinke bilateralne i multilateralne suradnje na području Jugoistočne Europe kroz posljednja četiri desetljeća.Despite its new political, economic and social features, created after the collapse of the Berlin Wall and the creation of a new world order, Southeast Europe is still considered to be one of the most unstable areas of Europe. Numerous initiatives have been launched by the international community with the aim of stabilizing Southeast Europe and preserving peace. Southeast Europe is an area extremely rich in history, different religions, cultures and customs, but also in a number of open questions regarding cooperation between countries in this area. Regional cooperation in Southeast Europe is achieved trough numerous initiatives that promote economic, political and security integration but their effectiveness depends on political will and the stability of the countries. While some countries are more actively involved in cooperation processes, differences in priorities and institutional capacities affect their success. The aim of this paper is to analyze and compare the characteristics and effects of bilateral and multilateral cooperation in Southeast Europe over the last four decades, based on a review of scientific and professional papers and online sources
Investigation of the stability and SERS efficiency of gold nanoparticles prepared in HEPES buffer
No full textUV/VIS i SERS spektroskopijom istražena je stabilnost tijekom vremena i SERS učinkovitost koloidnih nanočestica zlata nastalih reakcijom tetraklorozlatne(III) kiseline i 4-(2-hidroksietil)- 1-piperazinetilensulfonske kiseline (HEPES). Kao modelne molekule korišteni su rodamin 6G (R6G) i (E)-1,2-di(piridin-4-il)eten (BPE). Koloidi zlata pripremljeni su sa i bez dodatka srebrova(I) nitrata te su uspoređeni s koloidima kojima su dodani stabilizatori nanočestica; cetiltrimetilamonijev bromid (CTAB), odnosno N,N-di-(3-aminopropil)butan-1,4-diamin (spermin). U svim pripravljenim koloidima najjače pojačanje raspršenja zračenja opaženo je za molekule BPE, zbog karakteristične strukture bez naboja. Molekule R6G daju intenzivne spektre samo u nemodificiranim koloidima zbog elektrostatskog odbijanja pozitivno nabijenih molekula R6G i molekula stabilizatora koje okružuju nanočestice u modificiranim koloidima. CTAB se pokazao kao bolji stabilizirajući agens nanočestica zlata u odnosu na spermin. Dodatak AgNO3 tijekom sinteze koloida rezultira nastankom nanočestica koje intenzivnije pojačavaju raspršenje zračenja, u usporedbi s koloidima bez dodatka srebrova(I) nitrata.The UV/VIS and SERS spectroscopy were used to investigate the stability over time and the SERS efficiency of colloidal gold nanoparticles formed by the reaction of tetrachloroauric(III) acid and 4-(2-hydroxyethyl)-1-piperazineethylenesulfonic acid (HEPES). Rhodamine 6G (R6G) and (E)-1,2-di(pyridin-4-yl)ethene (BPE) were used as model molecules. Gold colloids were prepared with and without the addition of silver(I) nitrate and were compared with colloids to which nanoparticle stabilizers were added; cetyltrimethylammonium bromide (CTAB) and N,N-di-(3-aminopropyl)butane-1,4-diamine (spermine). In all prepared colloids, the strongest radiation scattering enhancement was observed for BPE molecules, due to their characteristic uncharged structure. R6G molecules give intense spectra only in unmodified colloids due to electrostatic repulsion between positively charged R6G molecules and stabilizer molecules surrounding the nanoparticles in modified colloids. CTAB has been shown to be a better stabilizing agent for gold nanoparticles than spermine. The addition of AgNO3 during the synthesis of the colloids results in nanoparticles that enhance the scattering of radiation more intensely compared to colloids without the addition of silver(I) nitrate
THE EFFECT OF ASCORBATE ON SARCOMA-DERIVED CANCER STEM CELLS
No full textAgresivnost sarkoma koja se očituje u otpornosti na terapiju i jakoj sklonosti metastaziranju se
pripisuje tumorskim matičnim stanicama (CSC, engl. cancer stem cells). Kako bi se ispitala
osjetljivost CSC sarkoma na askorbat, CSC su izolirane iz šest uzoraka sarkoma te je potvrđen
njihov matični karakter. Ispitivanje citotoksičnosti askorbinske kiseline, dehidroaskorbinske
kiseline i askorbil palmitata ugrađenog u čvrste lipidne nanočestice na CSC je pokazalo kako je
optimalno primjenjivati askorbat u slobodnom obliku. Uz to, prisutnost bazičnog fibroblastnog
faktora rasta (bFGF) utječe na citotoksični učinak askorbata. Sedmodnevni tretman CSC
askorbatom u slobodnom obliku je ukazao kako dehidroaskorbinska kiselina u prisutnosti bFGF
postiže jači učinak na oksidacijski stres, ali i stanični metabolizam. Ustanovljeno je kako u
liposarkomu i rabdomiosarkomu proliferacijski signali od bFGF i mutiranih signalnih puteva u
prisutnosti dehidroaskorbinske kiseline ne dovode do proliferacije već do stanične smrti.The aggressiveness of sarcomas, characterized by therapy resistance and high metastatic potential,
is attributed to cancer stem cells (CSC). To investigate the sensitivity of sarcoma CSC to ascorbate,
CSC were isolated from six sarcoma samples, and their stemness was confirmed. Cytotoxicity
testing of ascorbic acid, dehydroascorbic acid, and ascorbyl palmitate incorporated into solid lipid
nanoparticles on CSC demonstrated that ascorbate in free form is optimal for application.
Additionally, the presence of basic fibroblast growth factor (bFGF) influenced cytotoxic effects. A
seven-day treatment of CSCs with free-form ascorbate revealed that dehydroascorbic acid in the
presence of bFGF had a stronger impact on oxidative stress and cellular metabolism. It was found
that, in liposarcoma and rhabdomyosarcoma, proliferative signals from bFGF and mutated
signaling pathways, in the presence of dehydroascorbic acid, do not lead to proliferation but
instead cause cell death
Toxicity of serotonin reuptake inhibitors on zebrafish (Danio rerio) embryos
No full textAntidepresivi postaju jedni od najčešće propisivanih lijekova u svijetu. Međutim, ekotoksični učinci
njihovih aktivnih spojeva još uvijek su slabo poznati. U ovom radu istraženi su učinci tri spoja sa svojstvom
inhibicije ponovne pohrane serotonina: citalopram, tramadol i nortriptilin te njihova smjesa. Koristile su se
okolišno relevantne koncentracije (0,001, 0,01, 0,1 i 0,5 mg/L). Izlaganje embrija ribe zebrice (Danio rerio)
ovim spojevima u trajanju od 120 sati uzrokovalo je kardiotoksične učinke te povišenu razinu oksidativnog
stresa. Zabilježene su promjene u lokomotornom ponašanju pri čemu je jasno uočen smanjen odgovor na
podražaje iz okoliša te manja prijeđena udaljenost životinje što može značajno utjecati na stopu
preživljavanja u prirodnom staništu. Koncentracije od 0,5 mg/L za sve spojeve, kao i koncentracija od 1,5
mg/L smjese spojeva, izazvale su najveće promjene. Praćena su i morfološka obilježja ličinki te pokreti
repne peraje gdje nije bilo statistički značajnih promjena. Ovaj rad potvrđuje da farmaceutski aktivni spojevi
imaju mogućnost djelovati na životinje na sličan način kao što djeluju na ljude. Rezultati ukazuju da ispitane
koncentracije neuroaktivnih spojeva imaju štetan učinak na vodene organizme uslijed farmakoloških
svojstava lijeka, odnosno sposobnosti djelovanja lijeka pri niskim koncentracijama, kontinuirane izloženosti
i potencijalno sinergijskog djelovanja.Antidepressants are becoming some of the most prescribed medications worldwide. However, the
ecotoxicological effects of their active compounds are still poorly understood. This study investigated the
effects of three serotonin reuptake inhibitors: citalopram, tramadol, and nortriptyline, as well as their
mixture. Environmentally relevant concentrations (0.001, 0.01, 0.1, and 0.5 mg/L) were used. Exposure of
zebrafish (Danio rerio) embryos to these compounds for 120 hours revealed cardiotoxic effects and caused
elevated levels of oxidative stress. Changes in locomotor behavior were observed, with a clearly reduced
response to environmental stimuli and a shorter distance traveled, which could significantly affect survival
rates in natural habitats. Concentrations of 0.5 mg/L for all compounds, as well as the concentration of 1.5
mg/L of the compound mixture, caused the greatest changes. Morphological characteristics of larvae and
tail fin movements were also monitored, with no statistically significant changes observed. This study
confirms that pharmaceutical active compounds can affect animals in a similar way to humans. The results
suggest that the tested concentrations of neuroactive compounds have harmful effects on aquatic organisms
due to the pharmacological properties of the drug, namely its ability to act at low concentrations, continuous
exposure, and potentially synergistic effects
Upper Miocene deposits of Drava depression
No full textPredmet istraživanja u ovome radu bile su gornjomiocenske turbiditne naslage Dravske depresije. Te su naslage zanimljive s naftnogeološkog stajališta jer mogu imati izvrsna ležišna svojstva, a njihov postanak vezan je za progradaciju klastičnih sustava i postupno zatrpavanje JZ dijela Panonskog bazenskog sustava. U sklopu rada na tri naftno-plinska polja (A-C), jednom plinskom polju (E) i jednom području bez pojave ugljikovodika (D) provedena je kompleksna geološka analiza. Na temelju sedimentološko-petrografskih analiza jezgara iz Fonda stručne dokumentacije INA-e određeni su glavni litofacijesi: masivni pješčenjaci (LF1), tankoslojeviti pješčenjaci, siltiti i lapori (LF2), siltozni lapori (LF3) i kalcitom bogati lapori (LF4). LF1 interpretiran je kao Ta interval Bouma sekvencije, LF2 kao podsječene Bouma sekvencije tipa Tb-e, Tc-e i Td-e, dok su LF3 i LF4 interpretirani kao donji, odnosno gornji dio Te interval Bouma sekvencije. Pomoću karotažnih i seizmičkih podataka te pojave PL_UNC za polje A i područje D utvrđen je kontinentalni taložni okoliš, za polje B aluvijalno/šelfno/deltni i za polje E okoliš padina/krovina bazenskih turbidita. Analizom propusnosti i poroznosti istraživanih naslaga utvrđen je trend smanjenja propusnosti i poroznosti idući od SZ prema JI depresije kao i idući od proksimalnih prema distalnim turbiditima.The subject of this study were the Upper Miocene turbidite deposits of the Drava Depression. These deposits are interesting from a petroleum-geological point of view because they can have excellent reservoir properties, and their formation is related to the progradation of clastic systems and the gradual filling of the SW part of the Pannonian Basin System. As part of the work a complex geological analysis was carried out on three oil and gas fields (A-C), one gas field (E), and on one area without hydrocarbons (D). Based on sedimentological and petrographic analyses of cores from the INA Technical Documentation Fund, four main lithofacies were determined: massive sandstones (LF1), thin-bedded sandstones, siltstones and marls (LF2), silty marls (LF3) and calcite-rich marls (LF4). LF1 was interpreted as the Ta interval of the Bouma sequence, LF2 as incomplete Bouma sequences of the Tb-e, Tc-e and Tde types, while LF3 and LF4 were interpreted as the lower and upper part of the Te interval of the Bouma sequence, respectively. Using wireline logging and seismic data and the PL_UNC occurrence, a continental depositional environment was determined for field A and area D, an alluvial/shelf/deltaic environment for field B, and a slope/uppermost part of basin turbidite environment for field E. The analysis of the permeability and porosity of the investigated deposits determined a trend of decreasing permeability and porosity going from the NW to the SE of the depression as well as going from proximal to distal turbidites
Triassic ichthyosaurs from European and Croatian localities
No full textIchthyosauria je red izumrlih morskih gmazova, koji je obitavao morima od trijasa do krede. Naziv ihtiosaur dolazi od grčkih riječi ichthys, što znači riba i sauros, što znači gušter. Ihtiosauri su bili najspecijaliziraniji morski gmazovi. Ihtiosauri su bili viviparni, odnosno rađali su žive mlade. Zbog oblika tijela, koje je slično današnjim delfinima, perajama u obliku vesla i hipocerknoj repnoj peraji, smatra se da su bili izvrsni plivači. Evolucijska povijest ihtiosaura i dalje je dijelom nepoznanica. Primitivne značajke ranih ihtiosaura, ne ukazuju na povezanost s nekom posebnom skupinom kopnenih ili vodenih gmazova, od kojih su se ihtiosauri mogli razviti, odnosno nije poznat neki prijelazni oblik između njihovih terestričkih predaka i njih samih, međutim prisutnost dorzalnog temporalnog otvora, tzv. fenestre sugerira na sličnost s ranim dijapsidnim gmazovima.Ichthyosauria is an order of extinct marine reptiles that inhabited the seas from the Triassic to the Cretaceous period. The name ichthyosaur comes from the Greek words ichthys, meaning fish, and sauros, meaning lizard. Ichthyosaurs were the most specialized marine reptiles. They were viviparous, meaning they gave birth to live young. Due to their body shape, which resembled that of modern dolphins, their paddle-shaped fins, and hypocercal tail fin, they are believed to have been excellent swimmers. The evolutionary history of ichthyosaurs remains partly unknown. The primitive features of early ichthyosaurs do not indicate a connection with any specific group of terrestrial or aquatic reptiles from which they could have evolved, in other words, no transitional form between their terrestrial ancestors and themselves is known. However, the presence of a dorsal temporal opening, known as the fenestra, suggests a similarity to early diapsid reptiles