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Područje Sjevernog Velebita poznato je po razvijenim krškim oblicima, uključujući duboke speleološke objekte. Aktivna tektonika, glacijalna razdoblja i izloženost atmosferskim uvjetima utjecali su na koroziju stijena i razvoj krša na ovim područjima.Osim analize stijena i razvijenog reljefa, rezultati analize sedimenata iz speleoloških objekata također mogu doprinijeti razumijevanju njihovog nastanka i geoloških procesa na užem području. Spoznaja raznolikosti stijena, geoloških struktura, minerala i fosila doprinose georaznolikosti područja, dok su speleološki objekti izuzetni i značajni primjeri geolokaliteta čije je očuvanje od neizmjerne znanstvene i ekološke važnosti. U svrhu istraživanja odabrane su dvije jame s područja Sjevernog Velebita, jama Nedam na Hajdučkim i Rožanskim kukovima, te Ledena jama u Lomskoj dulibi. Oba spomenuta područja su od velikog geomorfološkog značaja zbog specifično razvijenog reljefa i krških oblika. Jama Nedam drugi je najdublji speleološki objekt u Hrvatskoj s dubinom od 1335 m, te se u njenoj neposrednoj blizini nalaze i ostale duboke jame: Lukina jama – Trojama (-1431 m), Slovačka jama (-1324 m), jama Velebita (-1026 m) i dr. Jama Nedam zanimljiva je zbog izmjene uskih meandara i širokih vertikala, te specifičnog nepristupačnog terena Hajdučkih kukova gdje joj je smješten ulaz. Ledena jama smještena je u glacijalnoj dolini Lomska duliba, okružena visokim planinskim vrhovima, a svoju specifičnost krije u debelom sloju leda prisutnom tijekom cijele godine na dubini od 50 do 90 metara. Jedan od ciljeva ovog istraživanja bio je utvrđivanje prisutnih stratigrafskih jedinica i njihovih kontakata u jami Nedam, te utvrđivanje stratigrafske jedinice na ulaznim dijelovima Ledene jame. Uzroci koji pripadaju istim stratigrafskim jedinicama u obje jame su međusobno i uspoređeni. Drugi cilj istraživanja bio je mineraloška analiza sedimenata iz obje jame, te njihova usporedba. Ovisno o veličini frakcije, provedene su različite analize u svrhu dobivanja što iscrpnijih informacija o mineralnom sastavu i mogućoj provenijenciji sedimenata. Uzorci su prikupljeni tijekom speleološke ekspedicije ˝Nedam 2020.˝ u organizaciji Speleološkog odsjeka PDS Velebit, Komisije za speleologiju Hrvatskog planinarskog saveza te Nacionalnog parka Sjeverni Velebit.

Caves formed in karst terrains are often trapping big amounts of different kinds of sediments. Cave sediments can be very useful for the determination of conditions and processes that were present at the time of their deposition. They are usually well preserved so they can give us a lot of i nformation about changing of the conditions over a long period (sometimes even over a few million years). One of the key methods that can provide us with a deeper insight into the complex karst systems is magnetic susceptibility, which shows the magnetism of measured material. Magnetic susceptibility measuring allows recognition of iron-rich minerals (together with their concentration and volume), classification of different types of materials and a better understanding of tectonic events. This is also particularly important in the context of exploration of karst waters that are important from the aspect of vulnerable karst ecosystems and strategic reserves of drinking water. In this research, two caves were chosen for sediment analysis. Both caves are located in the northern part of Velebit mountain, named Nedam and Ledena jama. Nedam is Croatia's fourth deepest pit with a depth of 1021 m. Ledena jama, is 536 m deep pit that is significant by the perennial ice between depths of 50 and 160 m, and is located in a paleoglacier valley. Nedam is located on steeper and more inaccessible karst terrain. The entrances are at different altitudes – at 1420 m for Nedam, and at 1235 m for Ledena jama. That altitude difference and different terrain morphology (paleoglacier valley vs. steep karst), suggest that interesting differences in the sediments studied may be present. Sediment samples were taken at 50 m depth in Ledena jama, and at 100 m depth in Nedam. Preliminary magnetic measurements were performed using the SM30 instrument (ZH instruments). The additional analyzes made on the sediment samples were the determination of mineralogical composition – identification of clay minerals by X-ray diffraction analysis, separation of light and heavy mineral fraction, and observing under the microscope. Magnetic research provides complementary data to these methods. From this analyzes, we can deduce the province of the sediments, and some conditions that were present during their deposition and terrain formation. The mineral composition of the samples from both pits was compared. This work was done in collaboration with Northern Velebit National Park, Krasno (project Exploration of the deep pits of the Northern Velebit National Park), Department of Geology, Faculty of Science, University of Zagreb and Speleological Society Velebit, Zagreb.

The topic of climate change is one of the fronts of scientific research in the 21st century. A special focus of speleological research is the discovery of records of climate change in caves. However, the question arises as to the impact of climate change on the conditions of speleological research and on the hydrological dynamics in karst. Extreme weather conditions around the world have become more frequent. That is why we need to define new standards of speleological research. New recommendations to the speleological community should include methods for monitoring, collecting and analyzing climate data for risk assessment purposes. Analyzes of hydrological extremes and other climate-related processes in karst and caves are of interest to the wider community. We will highlight examples from the Dinaric Karst in Croatia (deep pits, hydrologically active caves, caves with ice).

The aim of the research is to contribute the knowledge of surface and underground karst relief in the area of West Medvednica Mt.

Caves formed in karst cavities are often trapping big amounts of different kinds of sediments. Cave sediments can be very useful for the determination of conditions and processes that were present at the time of their deposition. In this research two caves where chosen for sediment analysis.

Natural processes of sudden rockfall, other than water erosion, frost weathering and temperature change were observed in Dinaric karst.

Cave sediments and speleothems are valuable archives of past environmental conditions due to their large geographic extent and extensive time scales. They contain geochemical and paleoenvironmental data and therefore represent one of the front lines in research of paleo processes in paleo environments. The Dinaric karst of Croatia, characterized by complex and deep caves, is a promising location for this kind of research. The complexity and large dimensions open the need for the introduction of fast and inexpensive methods that can detect locations and patterns for further detailed research. We aim to introduce the relatively new method of magnetic susceptibility (MS) in environmental research in Croatian karst, in addition to usually used geochemical and mineralogical methods. First such measurements in Croatia were performed by Frančišković- Bilinski (2008) on the samples from Kupa River watershed. Preliminary measurements showed the highest values of magnetic susceptibility in the lower flow of Mrežnica river and increased values of magnetic susceptibility in the upper flow of the Dobra River. Elevated values of MS, thus elevated concentrations of heavy metals, could be of natural or anthropogenic causes, or sometimes combination of them. In deep pits of Croatian karst most of elevated values are results of natural processes, e.g. in Lukina jama pit, where largest number of element anomalies are present. In Lukina jama a whole series of elements, including many heavy metals, show extreme values (Pb, Cu, Zn, Mn, Ni, Cr, Co, Ba, K, Mg, Li, Be, Al, U, Si, Ti, W, Fe, As). We aim to determine those processes, which caused such elevated concentrations of particular elements and in such way to reconstruct paleoenvironmental conditions. Our current investigations aim to investigate changes of MS and elemental concentrations with depth, which we are studying on examples of two deep pits – Slovačka jama pit and Cave system Velebita. The most recent study was performed by Kamenski (2018) in three profiles in Slovačka jama pit and in two profiles in Kita Gaćešina-Draženova puhaljka pit, where magnetic susceptibility was measured. Obtained MS results were compared with mineral composition, obtained by X-ray powder diffraction (XRD). It was concluded that samples with values higher than 50x10-5 SI contain minerals which contain metals, e.g. iron, aluminum, etc. Samples with higher metal content have proportionally higher MS values. Sediments with prevailing carbonate minerals and quartz are diamagnetic and have lower MS values, lower than 40x10-5 SI. For full understanding of precipitation processes of cave sediments, a series of additional MS measurements are necessary along the whole cave/pit length/depth. Then, on locations with large MS variation sampling should be performed and later elemental and mineralogical content analyzed. Rererences: Frančišković-Bilinski, S. (2008). Mineralogical Magazine 72, 1, 43-48. Kamenski, A. (2018). Diploma thesis, Faculty of Mining, Geology and Petroleum Engineering, University of Zagreb.

Fractal analysis addresses an important problem in the study of nature. Natural phenomena are complex, and their understanding requires many years of scientific research. There are no methods that can be described quantitatively in a faster way. Determining the fractal dimension is one of the prospective techniques if appropriate a way to connect with geological, hydrological and physical processes in nature. Dimensions in the case of regular geometric figures, such as lines, squares and cubes integer: 1, 2, 3. However, in nature there are structures (fractals) that do not have the whole spatial dimension. The technique presented in this work is aimed at the determination the fractal dimension and analysis of the longest cave of Dinaric Karst (length is 32 km). For the Cave system Kita Gaćešina (Velebit Mt., Croatia) fractal dimension up to 2.4 was determined, which confirms that the network of cave channels has a fractal structure. This is a significant result that requires further interpretation in framework of geological studies.

Health tourism in Croatia has many opportunities for development, especially within protected areas, such as Nature Park Medvednica. Hidden in the woods of Medvednica Mt., the Brestovac Sanatorium (built in 1909) was, during the first half of the 20th century, one of the best tuberculosis care facilities in all of Europe. In the natural environment of Medvednica Mt., one of the biggest caves of Croatian karst is situated. It is over 7 km long Veternica Cave, known for its complex geological history, paleontological discoveries, signs of presence of Neanderthals and present animals – 18 species of bats were recorded. Since in the summer period, the first 380 m are open for tourists, the idea of staying in a cave for the purpose of speleotherapy is introduced. To consider this, it is necessary to explore the climate, geochemical and biological properties of the environment. At the same time, it should be determined whether the longer human presence in the cave has influence on the microclimatic properties. Within this work, we give an overview of the present knowledge and guidelines for further research.

Transformacija obrazovnog sustava polazi od dvije ključne komponente: reduciranja izbora tema koje djeca uče te razvoja metoda s naglaskom na istraživačku i problemski orijentiranu nastavu uz što više izvanučioničke nastave. Fizičari trebaju prirediti sadržaje prikladne za učenje od rane dobi. No, koje teme su važne? Odgovor je jasan – to su aktualne teme vezane uz razvoj znanosti i tehnologije. Ako se priča gradi oko takvih, uzbudljivih, intrigantnih i u pravilu još u potpunosti nerazjašnjenih tema, interes učenika je znatno veći. Primjer takve teme, koja je stavljena na margine aktualnog obrazovnog sustava, a predstavlja ogroman potencijal u razvoju novih tehnologija je fenomen supravodljivosti.

Modern education in Croatia tends to put central emphasis on competences within the scientific education (STEAM = Science, Technology, Engineering, Arts and Mathematics), as these knowledge and skills are the foundations of the 21st century jobs. Emphasis is placed on project teaching, out‐of‐class‐learning concept, and interdisciplinarity. It demands development and introduction of new teaching methods and contents related to the biggest problems in the world today, from local to global issues. Numerous researches show the effectiveness of the outdoor education as a part of out‐of‐class learning in which pupils and students interact with the real‐world experience in a natural environment. It is also well‐known that learning in natural environment affords a wide range of benefits: educational, health, cultural and social. Karst and caves are ideal locations that can serve as outdoor classrooms for learning about natural processes from various aspects but also for application of different knowledge and skills. But besides pupils and students as "end users" of education, it is important to prepare teachers for these new forms of teaching. For the needs of preparing out‐of‐ class geography and physics teaching projects in primary and secondary schools, we formed a working group of scientists and practitioners (geographers, physicists, experts in geography teaching methodology, experts in nature conservation) that developed a programme for teacher education and preparation. A key idea was to highlight the development of programs for formal education and, at the same time, encouraging scientific activities whose results can be included in these programs. We also addressed the importance of collaboration of higher education, schools and nature (cave) management service. This project was realized in cooperation between several institutions: Faculty of Science (UNIZG), Education and Teacher Training Agency, Public Institution for the Management of Geomorphologic Monuments of Nature "Cave Park Grabovača", Croatian Geographical Society and Croatian Geomorphological Society.

Ulascima u špilje i jame speleolozi obavljaju stalni monitoring, koji je neophodan kako bi se na vrijeme uočila zagađenja ili drugi izvori ugrožavanja, te potaknula zaštita i sanacija. Ustanove koje upravljaju zaštićenim područjima nisu ekipirane, niti će u usporedbi sa stanjem u EU biti to u budućnosti, za obavljanje takvog monitoringa u podzemlju. Više stotina aktivnih speleologa u Hrvatskoj stoga predstavljaju važan izvor informacija o stanju u hrvatskom podzemlju, te mogu potaknuti od tih ustanova biti odlični suradnici u zaštiti prirode i inventarizaciji prirodnih vrijednosti.

Terenska nastava je nezaobilazan dio nastavnog procesa u geografiji. Najjednostavnije se može definirati kao način rada izvan učionice u kojem se za poučavanje i učenje koriste "iskustva iz prve ruke" (Lambert i Reiss, 2014). Svi dionici nastavnog procesa će se složiti kako je to najefektniji oblik učenja i poučavanja, a to pokazuju i studije (Mackenzie i White, 1981; Herrick, 2010). Učiteljima pruža mogućnost različitih oblika prezentiranja i demonstriranja sadržaja s naglaskom na objašnjavanju složenih prostornih veza i odnosa na geografskim (interdisciplinarnim, holističkim) principima, te povezivanja nastavnih sadržaja i stvarnosti što nastavu čini zanimljivijom. Temelji se na funkcionalnom promatranju i uočavanju kompleksnosti geoprostora (Brazda, 1985). Terenski oblik nastave omogućuje primjenu stečenih znanja i svladavanje vještina što je u učionici nemoguće ostvariti na odgovarajući način. Terensko iskustvo učenicima omogućuje da apstraktne pojmove usvojene u učioničkoj nastavi povežu s pojavama i procesima u prostoru, da ih provjere i potvrde u stvarnim uvjetima te da ih znaju korisno upotrijebiti.

Microwave absorption measurements in magnetic fields from 0 up to 16 T were used to determine the temperature range of superconducting fluctuations above the superconducting critical temperature Tc in YBa2Cu3O7−δ. Measurements were performed on deeply underdoped, slightly underdoped, and overdoped single crystals. The temperature range of the superconducting fluctuations above Tc is determined by an experimental method which is free from arbitrary assumptions about subtracting the nonsuperconducting contributions to the total measured signal and/or theoretical models to extract the unknown parameters. The superconducting fluctuations are detected in the ab plane, and c-axis conductivity, by identifying the onset temperature T′. Within the sensitivity of the method, this fluctuation regime is found only within a fairly narrow region above Tc. Its width increases from 7 K in the overdoped sample (Tc=89 K) to, at most, 23 K in the deeply underdoped sample (Tc=57 K), so that T′ falls well below the pseudogap temperature T∗. Implications of these findings are discussed in the context of other experimental probes of superconducting fluctuations in the cuprates.

Temperature and magnetic field dependent measurements of the microwave surface impedance in the novel superconductor LaO_0.9F_0.1FeAs reveal a very large upper critical field (\Bc2~$\approx 56$T) and a large value of the depinning frequency (f_0 \approx 6GHz) together with the measured effective penetration depth, \lambda_eff=200 \pm 50$nm, our results indicate a stark similarity between this system and the high-T_c superconducting cuprates.

We have performed 75As nuclear magnetic resonance measurements on aligned powders of the new LaFeAsO0:9F0:1 superconductor. In the normal state, we find a strong temperature dependence of the spin shift and Korringa behavior of the spin lattice relaxation rate. In the superconducting state, we find evidence for line nodes in the superconducting gap and spin-singlet pairing. Our measurements reveal a strong anisotropy of the spin lattice relaxation rate, which suggests that superconducting vortices contribute to the relaxation rate when the field is parallel to the c axis but not for the perpendicular direction.

Ru(1-x)SnxSr2EuCu2O8 and Ru(1-x)SnxSr2GdCu2O8 have been comprehensively studied by microwave and dc resistivity and magnetoresistivity and by the Hall measurements. The ruthenium magnetic ordering temperature Tm is considerably reduced with increasing Sn content. However, doping with Sn leads to only slight reduction of the superconducting critical temperature Tc accompanied with the increase of the upper critical field Bc2, indicating an increased disorder in the system and a reduced scattering length of the conducting holes in CuO2 layers. In spite of the increased scattering rate, the normal state resistivity and the Hall resistivity are reduced with respect to the pure compound, due to the increased number of itinerant holes in CuO2 layers, which represent the main conductivity channel. Most of the electrons in RuO2 layers are presumably localized, but the observed negative magnetoresistance and the extraordinary Hall e® ; ; ; ect lead to the conclusion that there exists a small number of itinerant electrons in RuO2 layers that exhibit colossal magnetoresistance.

Field and temperature microwave measurements have been carried out on MgB2 thin film grown on Al2O3 substrate. The analysis reveals the mean field coherence length xi_{MF} in the mixed state and a temperature independent anisotropy ratio gamma_{MF} = xi_{MF}^{ab} / xi_{MF}^c approximately 2. At the superconducting transition, the scaling of the fluctuation conductivity yields the Ginzburg-Landau coherence length with a different anisotropy ratio gamma_{GL} = 2.8, also temperature independent., Comment: submitted to PRL

We have performed susceptibility, thermopower, dc resistance and microwave measurements on RuSr2EuCu2O8. This compound has recently been shown to display the coexistence of both superconducting and magnetic order. We find clear evidence of changes in the dc and microwave resistance near the magnetic ordering temperature (132 K). The intergranular effects were separated from the intragranular effects by performing microwave measurements on a sintered ceramic sample as well as on a powder sample dispersed in an epoxy resin. We show that the data can be interpreted in terms of the normal-state resistivity being dominated by the CuO2 layers with exchange coupling to the Ru moments in the RuO2 layers. Furthermore, most of the normal-state semiconductor-like upturn in the microwave resistance is found to arise from intergranular transport. The data in the superconducting state can be consistently interpreted in terms of intergranular weak-links and an intragranular spontaneous vortex phase due to the ferromagnetic component of the magnetization arising from the RuO2 planes., 20 pages including 6 figures in pdf format. To be published in Phys. Rev. B

We have performed ac susceptibility, thermopower, dc resistance and microwave measurements on RuSr_2EuCu_2O_8. This compound has recently been shown to display the coexistence of both superconducting and magnetic order. We find clear evidence of changes in the dc and microwave resistance near the magnetic ordering temperature (132 K). The intergranular effects were separated from the intragranular effects by performing microwave measurements on a sintered ceramic sample as well as on a powder sample dispersed in an epoxy resin. We show that the data can be interpreted in terms of the normal-state resistivity being dominated by the CuO_2 layers with exchange coupling to the Ru moments in the RuO_2 layers. Furthermore, most of the normal-state semiconductor-like upturn in the microwave resistance is found to arise from intergranular transport. The data in the superconducting state can be consistently interpreted in terms of intergranular weak-links and an intragranular spontaneous vortex phase due to the ferromagnetic component of the magnetization arising from the RuO_2 planes.

The microwave response of a thin film of high temperature superconductor YBa2Cu3O7 - δ was measured for a wide region of temperatures and magnetic fields. From the measured complex frequency shift, the complex conductivity was calculated. The model for effective conductivity in the mixed state was fitted to the complex conductivity data and the values of upper critical fields Bc2(T) and depinning frequencies ω0 (T) have been obtained as fitted parameters., Mjerili smo mikrovalni odziv tankog filma visokotemperaturnog supravodiča YBa2Cu3O7−δ u širokom području temperatura i magnetskih polja. Iz izmjerenog kompleksnog frekventnog pomaka izračunali smo kompleksnu vodljivost. Numeričkom prilagodbom modela efektivne vodljivosti u miješanom stanju odredili smo vrijednosti gornjeg kritičnog polja Bc2 (T) i frekvencije opuštanja ω0(T).

Tema klimatskih promjena u školskom obrazovanju, a naročito u nastavi fizike, zastupljena je minimalno u odnosu na njenu važnost. Fizika kao eksperimentalna znanost mora učenicima ponuditi eksperimentalni pristup toj temi kako bi samostalno došli do opažanja i time bolje razumjeli klimu na globalnoj razini. Ovaj rad temelji se na korištenju micro:bita u kombinaciji s vanjskim senzorima, kao jednostavnog mjernog instrumenta. Mikroračunala, posebice micro:bit, imaju brojne prednosti i mogućnost brze implementacije u nastavni proces. Ovakvi pokusi omogućavaju učenje programiranja i uvid u principe rada suvremenih mjernih uređaja. Rad je osmišljen kao uputa nastavnicima za uvođenje teme klimatskih promjena u nastavu fizike. Kao središnja aktivnost odabran je učinak staklenika kao jedna od najvažnijih tema u kontekstu proučavanja klimatskih promjena. Uz osnovne principe učinka staklenika, dane su upute za kodove potrebne za programiranje micro:bitova, primjeri pokusa koje je moguće uvesti u nastavu s pojašnjenjima, primjerima mjerenja i analize podataka, motivacijskim pitanjima i popratnim materijalima za učenike. The topic of climate change in school education, and especially in the teaching of physics, is represented minimally in relation to its importance. Physics, as an experimental science, must offer students an experimental approach to the subject in order to independently come to observations and thereby better understand the climate on a global scale. This work is based on the use of the micro:bit, in combination with external sensors, as a simple measuring instrument. Microcomputers, especially micro:bit, have numerous advantages and the possibility of quick implementation in the teaching process. Such experiments enable learning programming and insight into the principles of operation of modern measuring devices. The thesis is designed as an instruction for teachers to introduce the topic of climate change into physics classes. As a central activity, the greenhouse effect was chosen as one of the most important topics in the context of studying climate change. In addition to the basic principles of the greenhouse effect, there are instructions for the codes needed to program the micro: bits, examples of experiments that can be introduced into classes with explanations, examples of measurement and data analysis, motivational questions and accompanying materials for students.

Fizikalni pokus treba biti dio svakog sata fizike. Postavlja se pitanje koje pokuse izabrati, koja je za to potrebna oprema i koliko vremena treba nastavniku za pripremu. Mikroračunala poput micro:bita omogućavaju relativno brzu konstrukciju pokusa u kome se koriste njegovi interni ili vanjski senzori. U ovom radu su dane smjernice za izvođenje nekoliko pokusa koji su vezani uz temu valova u fizici. Slično se može izvesti u brojnim drugim područjima fizike. Pri tome se uči osnove programiranja i upravljanje sa senzorima, prijenos i obrada podataka. Osim toga ideja je i učiniti fiziku zanimljiviju učenicima, potaknuti ih da samostalno istražuju kroz projekte, ali i izvode grupna istraživanja vezana uz važne teme današnjice. A physics experiment should be part of every physics lesson. The question arises as to which tests to choose, what equipment is needed and how much time the teacher needs to prepare. Microcomputers like the micro:bit enable relatively fast construction of experiments using its internal or external sensors. In this thesis, guidelines are given for performing several experiments related to the topic of waves in physics. The same can bed one in many other areas of physics. In doing so, several subject are connecter interdisciplinary, for example, physics with computer science and mathematics. In doing so, the basic of programming and sensor management, dana transmission and processing are learned. In addition, the idea is to make physics more interesting to students, to encourage them to independently research through projects, but also to carry out group research related to important topics of today.

Postoje brojne mogućnosti upotrebe mikroračunala u nastavi fizike čime se uvode novi elementi u izvedbu fizikalnih pokusa te se povezuju STEM područja. U radu demonstriramo upotrebu micro:bit uređaja u konstrukciji vremenskih vrata koja se mogu implementirati u nizu fizikalnih pokusa. Prikazano je nekoliko izvedbi vremenskih vrata koja su primjerena za uključivanje u nastavu fizike u osnovnoj i srednjoj školi te za samostalni rad i interaktivno upoznavanje sa fizikalnim konceptima kao što su: vrijeme, put, brzina, ubrzanje, frekvencija i sila. Analizom dobivenih rezultata ukazujemo na prednosti i nedostatke pojedinih izvedba i dajemo sugestije za uključivanje u nastavu fizike. There are numerous possibilities of using microcomputers in physics teaching, which introduces new elements in the performance of physical experiments and connects STEM fields. In this thesis, we demonstrate the use of micro:bit device in the construction of time gates that can be implemented in a series of physical experiments. Several designs of time gates are shown, which are suitable for inclusion in physics classes in primary and secondary schools and for independent work and interactive learning of physical concepts such as: time, path, speed, acceleration, frequency, and force. By analyzing the obtained results, we indicate the advantages and disadvantages of individual time gate performances and we give suggestions for inclusion in physics classes.

U modernim laboratorijima u atomskoj fizici, podatci se kontinuirano prikupljaju i bilježe. Zbog utjecaja koji temperatura i drugi atmosferski uvjeti imaju na vrlo osjetljive eksperimente, na primjer, optičke atomske satove [1], nužno je mjeriti i bilježiti ove parametre kako bi se postigla rekordna točnost mjerenja vremena koji ovakvi satovi omogućuju. U ovom radu je opisana izrada sustava za automatizirano, kontinuirano mjerenje, bilježenje i interaktivno prikazivanje parametara u Laboratoriju za hladne atome na Institutu za fiziku. Mjerenja su bazirana na Labjack i Pico uređajima. Ostvareno je kontinuirano mjerenje i bilježenje temperature na više točaka u laboratoriju. Most između mjerenja na uređajima i spremanja podataka u bazu baziran je na programskom jeziku Python. Podaci će se spremati u InfluxDB bazu podataka, te se mogu prikazivati interaktivno i u stvarnom vremenu. Ovaj postav služit će za daljnju nadogradnju i priključivanje novih mjernih instrumenata čiji će se podaci moći obrađivati, spremati i nadograđivati kako bude potrebno za vrijeme trajanja eksperimenta. In modern laboratories in atomic physics, data is continuously collected and logged. Due to the influence that temperature and other atmospheric conditions have on very sensitive experiments, for example, on optical atomic clocks, it is necessary to measure and log these parameters in order to achieve the record accuracy of time measurements that such clocks allow. This thesis describes the development of a system for automated, continuous measurement, logging and interactive display of parameters in the Laboratory for Cold Atoms at the Institute of Physics. Measurements are based on Labjack and Pico devices. Continuous measurement and logging of temperature at several points in the laboratory was achieved. The bridge between measuring on devices and saving data to a database is based on the Python programming language. The data will be stored in a InfluxDB database and can be displayed interactively and in real time. This setup will be used for further upgrading and connection of new measuring instruments whose data will be able to be processed, logged and upgraded as needed during the experiment.

Od veljače do svibnja 2022. provedena su terenska istraživanja u izvorišnome području potoka Vrapčaka u Parku prirode Medvednica. Na približno 3, 37 km2 površine utvrđena je pojava 95 izvora, od kojih se oko dvije trećine nalazi u kredno- trijaskim, a trećina u miocenskim naslagama. Izvorišno područje potoka Vrapčaka pretežno je umjereno raščlanjenog reljefa, uglavnom na znatno nagnutim padinama različitih orijentacija, te pokazuje odlike fluviodenudacijskoga reljefa. Prema Meinzerovoj podjeli izvora prema izdašnosti, više od polovice pronađenih izvora pripada VII. razredu (Q=0, 01-0, 1 L/s). Prema obliku staništa koje tvore, najviše je reo- i helokrenih, a od kombiniranih stanišnih tipova heloreokrenih izvora. Za 57 izvora mjereni su hidrološki fizikalno-kemijski parametri, električna vodljivost, temperatura vode, pH i količina otopljenih krutih tvari (TDS-a). Ovim su istraživanjem prvi put popisani, georeferencirani i kategorizirani izvori potoka Vrapčaka te su prikupljeni prvi podatci o izdašnosti i kakvoći njihove vode u trenutku pronalaska. Rezultati istraživanja trebali bi potaknuti daljnje, sustavnije i obuhvatnije istraživanje i praćenje stanja izvora, kao elemenata georaznolikosti diljem Medvednice, a preko njih i zagrebačkih potoka i ostalih hidroloških pojava na području Parka prirode Medvednica.

U radu su analizirani fosilni nalazi vrste vunasti mamut (lat. Mammuthus primigenius) evidentirani u Zbirci paleontološke građe Muzeja Međimurja Čakovec u razdoblju od 2003. godine do rujna 2022. godine. Fosilne ostatke najpoznatijeg predstavnika pleistocenske hladnodobne megafaune bilježimo i na području Međimurja. Recentni nalazi su iz aluvijalnih naslaga uz rijeku Muru te na aktivnim šljunčarama. Od 41 paleontološkog nalaza u Zbirci, njih 10 su nalazi vrste vunasti mamut. Najčešći su nalazi fosilnih zuba (5), a zabilježena je i zdjelična kost (1), bedrena kost (1), nadlaktica (1), potkoljenica (1) te kljova (1). Najveći broj nalaza je iz šljunčara, njih 6. Čak 3 fosilna zuba su nađena na šljunčari Ivanovec.

Danas, u suvremenom obrazovanju koje stavlja naglasak na znanja i vještine za nova zanimanja 21. stoljeća, nastava fizike ima sve veći utjecaj i značaj. U ovome se radu naglasak stavlja na rano učenje fizike, već u nižim razredima osnovne škole. Brojna istraživanja pokazuju da je susretanje djece sa STEM područjima (prirodoslovlje, tehnologija, inženjerstvo i matematika) bitno za njihov daljnji interes i motivaciju prema tim područjima. Djeca su u ranoj dobi jako znatiželjna, postavljaju puno pitanja te je tada pravi trenutak da im se predstave poticajni fizikalni koncepti. Ključan segment u nastavi fizike je pokus. Pokusi u nastavi fizike omogućuju djeci samostalno istraživanje te kod djece potiču maštovitost, razvijanje kritičkog razmišljanja i zaključavanja. Isto tako, u suvremenoj nastavi fizike dobro je implementirati primjere iz svakodnevnog života koji pobuđuju dodatni interes za fiziku. Sport je praktična aktivnost u kojoj se primjenjuju brojne fizikalne zakonitosti. Kako bi ih bolje razumjeli, postoje dvije opcije: jedna je detaljno istraživati - mjeriti gibanja i druge fizikalne pojave u sportu, a druga je osmisliti i izvoditi pokuse kojima bi se prikazale pojedine zakonitosti koje se primjenjuju u sportu. U radu se obrađuje nekoliko odabranih i prilagođenih primjera koji se mogu implementirati u kurikulum u osnovnoj školi, ponajviše u razrednoj nastavi. Today, in modern education that places emphasis on knowledge and skills for new occupations of the 21st century, the teaching of physics has an increasing influence and importance. In this thesis, the emphasis is placed on early learning of physics, already in the lower grades of primary school. Numerous studies show that meeting children with STEM areas (science, technology, engineering and mathematics) is essential for their further interest and motivation towards these areas. Children at an early age are very curious, they ask a lot of questions and then it is the right time to introduce them to stimulating physical concepts. A key segment in physics teaching is experimentation. Experiments in physics teaching enable children to explore independently and encourage children's imagination, development of critical thinking and reasoning. Likewise, in modern physics teaching it is good to implement examples from everyday life that arouse additional interest in physics. Sport is a practical activity in which a number of physical laws are applied. To better understand them, there are two options, one is to investigate in detail - to measure movements and other physical phenomena in sports, and the other is to design and perform experiments to show the individual laws applied in sports. This thesis deals with several selected and adapted examples that can be implemented in the curriculum in primary school, mostly in the classroom teaching.

Istraživački usmjerena nastava fizike potiče razvoj znanstvenog razmišljanja i zaključivanja. Učenici kroz istraživački usmjerenu nastavu razvijaju kritičko mišljenje, aktivno sudjeluju u nastavi te stječu znanja o samoj prirodi znanosti. Veliku ulogu u istraživački usmjerenoj nastavi fizike predstavlja pokus. Pokus, osim što nastavu čini zanimljivijom i zabavnijom, pruža izravno iskustvo učenicima o fizičkim pojavama. Pomoću pokusa učenici upoznavaju i istražuju nove pojave, te uz pokus uočavaju zakonitosti i testiraju hipoteze. Pri samom izvođenju pokusa kvantitativno se mjere fizičke veličine pri čemu pomažu mjerni instrumenti. Micro:bit kao suvremeno mikroračunalo može zamijeniti veći broj instrumenata i tako riješiti problem nedostatka opreme za izvođenje pokusa. Upoznavanje fizike na zabavan, kreativan i interdisciplinaran način uz korištenje tehnologije uvedeno je pomoću STEM pristupa obrazovanju. Research-oriented teaching of physics encourages the development of scientific thinking and reasoning. Through research-oriented teaching, students develop critical thinking, actively participate in teaching, and acquire knowledge about the very nature of science. Experiment plays a major role in research-oriented teaching of physics. The experiment, in addition to making teaching more interesting and fun, provides students with a direct experience of physical phenomena. With the help of the experiment, students get to know new phenomena, research about the phenomena, and with the experiment they notice the laws and test the hypotheses. During the experiment, physical quantities are measured quantitatively with the help of measuring instruments. Micro:bit as a modern microcomputer can replace a larger number of instruments and thus solve the problem of lack of equipment for performing experiments. Getting to know physics in a fun, creative and interdisciplinary way with the use of technology was introduced using the STEM approach to education.

Speleološki objekti nude pogled u geološke karakteristike koje mogu biti teško vidljive na površini. U ovom istraživanju odabrane su dvije jame Sjevernog Velebita za analizu i uspredbu stijena i sedimenata, Ledena jama i jama Nedam. U svrhu određivanja mineralnog sastava sedimenata korištena je metoda analize teške frakcije, te rendgenska difrakcija. Iz uzoraka sedimentnih stijena izrađeni su mikroskopski preparati u svrhu određivanja starosti i litološih karakteristika uzoraka. Rezultati analiza sedimenata pokazali su razliku u mineraloškom sastavu uzoraka, ovisno o njihovoj dubini. Rezultati određivanja starosti i litoloških karakteristika stijenskih uzoraka potvrdili su pretpostavljeni slijed naslaga, uz neočekivanu prisutnost sloja karbonatnih breča na većim dubinama. Caves offer a view of geological features that may be difficult to see on the surface. In this study, two caves of the Northern Velebit were selected for the analysis and comparison of rocks and sediments, the Ledena jama and the Nedam cave. To determine the mineral composition of sediments, the method of heavy fraction analysis and X-ray diffraction were used. Thin sections were made from sedimentary rock samples in order to determine the age and lithological characteristics of the samples. The results of sediment analyses showed a difference in the mineralogical composition of the samples, depending on their depth. The results of determining the age and lithological characteristics of the rock samples confirmed the assumed sequence of deposits, with the unexpected presence of a layer of carbonate breccias at greater depths.

Rad i energija su među ključnim konceptima u fizici i predstavljaju izazov u nastavi fizike u osnovnoj i srednjoj školi. Suvremeni pristup učenju fizike baziran je na učenicima zanimljivim pokusima i aktivnostima iz svakodnevnog života. U ovom radu izabran je konkretan primjer, olimpijski sportovi koji su izvrsna podloga za proučavanje koncepata rada i energije. Sport općenito je učenicima zanimljiv, a okvir u kojem se uči kako primjenom fizikalnih znanja poboljšati sportske rezultate predstavlja dodanu motivaciju u učenju fizike. U ovom radu kroz primjere iz konkretnih olimpijskih sportova i fizikalne pokuse dani su okviri kako ovaj pristup implementirati u okviru postojećih kurikuluma nastave fizike. Work and energy are among the key concepts in physics and present a challenge in physics education in primary and secondary schools. Modern approach to learning physics is based on interesting experiments and everyday activities which are interesting to students. In this work, specific example was chosen, Olympic sports which are a excellent base for studying concepts of work and energy. Sports in general are interesting to students, and the framework in which they study how to enhance sports results by applying physics knowledge presents additional motivation in physics learning. In this work, through examples from specific Olympic sports and physics experiments, frameworks are given on how to implement this approach within the given physics curricula.

Jedan od ključnih faktora koji utječu na kvalitetu učenja fizike na daljinu je motivacija učenika. Motivacija je već dulje tema istraživanja u kontekstu suvremenog obrazovanja. Kada govorimo o nastavi fizike, istraživano je utječu li upravo pokusi na motivaciju učenika. Pokusi iz fizike značajno utječu na motivaciju i mogu se primijeniti u nekoliko kognitivno motivacijskih tehnika poučavanja poput jednostavnih pokusa, problemskih i paradoksalnih pokusa, pokusa koje možemo primijeniti u svakodnevnom životu i dr. Za motivaciju učenika značajni su jednostavni fizikalni pokusi, koji ne iziskuju velika sredstva i ujedno otvaraju široki kreativan prostor za nastavnike. No istraživanje među hrvatskim nastavnicima fizike je pokazalo da preko 50 % nastavnika nije uspjelo motivirati učenike izvođenjem pokusa na daljinu. Svjetska istraživanja prikazana u ovom radu pokazala su da postoji niz metoda kako pokus učiniti zanimljivim, odnosno povećati motivaciju učenika, pri čemu se posebno ističe učinak jednostavnih pokusa. To otvara prostor unaprjeđenju nastave fizike u Hrvatskoj. One of the key factors influencing the quality of distance learning in physics is student motivation. Motivation has long been a research topic in the context of modern education. When we talk about teaching physics, it has been investigated whether experiments influence students' motivation. Experiments in physics significantly affect motivation and can be applied in several cognitively motivational teaching techniques such as simple experiments, problem and paradoxical experiments, experiments that we can apply in everyday life, etc. Simple physical experiments are important for motivating students, which do not require large funds and at the same time open a wide creative space for teachers. However, research among Croatian physics teachers has shown that over 50% of teachers have failed to motivate students by conducting distance experiments. Other research presented in this paper has shown that there are a number of methods to make the experiment interesting, i.e. to increase student motivation, with special emphasis on the effect of simple experiments. This opens space for the improvement of physics teaching in Croatia.

Nastava fizike, kao jedno od temeljnih STEM područja, u suvremenom obrazovanju ima sve veći značaj. U ovome radu stavljamo naglasak na rano učenje fizike, osobito koncepte sile. Upoznavanjem djece s konceptima prirodnih znanosti u razrednoj nastavi, dajemo mogućnosti za istraživanje, postavljanje raznih pitanja. Mnoga istraživanja pokazuju da je rano upoznavanje djece sa STEM područjem ključno za njihovo daljnje napredovanje i usmjeravanje ka tim područjima. Nastava fizike u središtu ima fizikalni pokus, koji nam omogućuje zanimljiviji pristup učenicima, te mogućnost njihovog samostalnog istraživanja. Djeca u ranoj dobi su znatiželjna, postavljaju pitanja, stoga trebamo iskoristiti to razdoblje da ih izložimo zanimljivim konceptima sile i potaknemo suradnju i istraživanja. U sklopu ovoga rada pokazujemo kako fiziku možemo uvesti već u razrednoj nastavi kroz koncept sile. Ako se djeca s njima nisu prije susrela, iste pokuse bi bilo dobro izvoditi u okviru odgovarajućih tema u kurikulumu fizike. Physics teaching, as one of the fundamental STEM fields, has an increasing importance in modern education. In this diploma thesis we put emphasis on early learning of physics, especially the concepts of force. By introducing children to the concepts of natural sciences in lower elementary school teaching, we provide opportunities for inquiry and asking questions. Great deal of studies demonstrate that early introducing children to the STEM field is crucial to their further progress and guidance towards these areas. Physics teaching has a physical experiment as its focus, which allows more interesting approach to students, and the possibility for their independent research. Children at an early age are curious and ask questions, therefore, we should use this period to expose them to interesting concepts of force and encourage their collaboration and research. In this diploma thesis we show how physics can be introduced in lower elementary school already, through the concept of force. If children have not encountered them before, the same experiments would be good to perform within the framework of appropriate topics in the physics curriculum.

Mobilni uređaji danas imaju brojne hardverske i softverske mogućnosti koje omogućuju široke primjene u nastavi fizike. Mobitel kao mjerni instrument može biti središnji dio znanstvene metode kojom se proučavaju određeni procesi, izvode kvantitativna mjerenja i na temelju njih donose zaključci. U kontekstu istraživački orijentirane nastave, mobitel predstavlja mali istraživački laboratorij kojim istražujemo različite fizikalne pojave. Diskusija da li je mobitelu mjesto u školi možda nije potrebna, jer se istraživanje u konačnici ne mora izvoditi na nastavnom satu. Činjenica je da djeca sve više vremena izvan škole provode na mobitelima te usmjeravanje barem dijela tog vremena na njima korisne obrazovne sadržaje može imati širi obrazovni učinak. Mobile devices today have a number of hardware and software capabilities that enable numerous applications in physics teaching. A mobile phone as a measuring instrument can be a central part of a scientific method that studies certain processes, performs quantitative measurements and draws conclusions based on them. In the context of research-oriented teaching, the mobile phone is a small research laboratory with which we investigate various physical phenomena. A discussion of whether a cell phone has a place in school may not be necessary, as research ultimately does not have to be conducted in class. The fact is that children are spending more and more time outside of school on mobile phones. Directing at least part of that time to useful educational content can have a wider educational effect.

Terenska nastava je oblik izvanučioničke nastave u kojoj se omogućuje učenje u izvornoj stvarnosti, a sastavni je dio svakog školskog kurikuluma. Tema ovog rada je posjet mobilnom planetariju kao oblik terenske nastave u okviru suvremenog znanstvenog obrazovanja. U radu su opisane tehničke karakteristike mobilnog planetarija i digitalni sadržaji. Pojašnjene su teme i koncepti koje učenici mogu naučiti, ali i miskoncepcije koje se mogu spriječiti ili ukloniti odlaskom u planetarij. Opisani su i pokusi koje učenici mogu vidjeti kako bi se dodatno razjasnile pojave koje nisu vidljive na samom nebu planetarija. Field teaching is a form of extracurricular teaching that enables learning in the original reality, and is an integral part of every school curriculum. The topic of this paper is a visit to the mobile planetarium as a form of field teaching in modern science education. The paper describes the technical characteristics of the mobile planetarium and digital content.Topics and concepts that students can learn are presented as well as misconceptions, but also misconceptions that can be prevented or eliminated by going to the planetarium. Experiments that students can see are also described to further elucidate phenomena that are not visible in the planetarium sky itself.

Mobitel sa svojim mogućnostima različitih aplikacija i upotrebe različitih senzora otvara brojne mogućnosti primjene u nastavi, posebice kao mjernog instrumenta. Pokazuje se da je izvedba pokusa s mobitelom učenicima zanimljiva. No isto tako zanimljivi su im i dobro koncipirani istraživački pokusi bez mobitela. U radu su dani primjeri upotrebe mobitela kao mjernih instrumenata u proučavanju gibanja. Zaključak je da se mobitel može koristiti u nastavi fizike ali treba biti umjeren u njegovoj primjeni. Učenici moraju osim s mobitelom izvesti dovoljno pokusa, analiza i grafičkih prikaza podataka bez mobitela kako bi savladali osnove analize i prikaza podataka. S druge strane korištenjem mobitela otvaraju se mogućnosti za složenije pokuse i istraživanja u okviru istraživački orijentirane nastave. The mobile phone with its possibilities of different applications and the use of different sensors opens up numerous possibilities for application in teaching, especially as a measuring instrument. It turns out that the performance of the experiment with a mobile phone is interesting for students. But they are also interested in well-designed research experiments without mobile phones. The paper gives examples of the use of mobile phones as measuring instruments in the study of motion. The conclusion is that the mobile phone can be used in physics teaching, but it should be moderate in its application. In addition to the mobile phone, students must perform sufficient experiments, analyzes and graphical representations of data without the mobile phone in order to master the basics of data analysis and data display. On the other hand, the use of mobile phones opens up opportunities for more complex experiments and research within research-oriented teaching.

Na samom početku rada naveden je razvoj suvremene nastave fizike. Opisana je interaktivna, istraživački usmjerena nastava fizike te osnovni sadržaji koji bi se trebali provoditi unutar nje. Isto tako, opisan je tijek sata koji kod učenika postiže najveću aktivnost te interaktivne nastavne metode kojima se postiže.Nadalje, prema Nacionalnom kurikulumu opisan je redoslijed nastavnog sadržaja vezanog za savladavanje sila. Nakon toga, objašnjen je pojam miskoncepcije te su prikazani rezultati ankete provedene na učenicima kako bi se usporedio učenički pojam sile unatrag tridesetak godina i danas. Iz rezultata ankete vidljivo je da učenici unatoč promjenama u nastavi fizike i dalje zadržavaju intuitivna objšnjenja pojava te je potrebno još poraditi na samom izvođenju nastave fizike. At the very beginning of the paper, the development of modern physics teaching is mentioned. Interactive, research-oriented teaching of physics is described, as well as the basic contents that should be implemented within it. Also, the course of the lesson that achieves the greatest activity in students is described, as well as the interactive teaching methods that are achieved. Furthermore, according to the National Curriculum, the repeated teaching content related to mastering forces is described. After that, the concept of misconception is explained and the results of a survey conducted on students are presented in order to compare the students' concept of force thirty years ago and today. The results of the survey show that despite the changes in physics teaching, students still retain intuitive explanations of the phenomena, and it is necessary to work on teaching physics.

U suvremenom obrazovanju, nastava fizike kao jedno od temeljnih STEM područja ima sve veći značaj. Ključna pitanja danas su kako učenike aktivno uključiti u nastavni proces, zainteresirati ih za fiziku i potaknuti dalje u smjeru STEM područja koja su okosnica zanimanja 21. stoljeća. O upotrebi mikroračunala u nastavi se već dugo razmišlja, no tek je prije 5 godina, konstrukcijom posebno dizajniranog mikroračunala BBC micro:bit, za potrebe obrazovanja u Europskoj uniji, došlo do masovne primjene u školama. Paralelno tome razvijaju se ideje i metode kako ih uključiti u nastavu pojedinih predmeta. Nastava fizike, koja u središtu ima fizikalni pokus, logično je mjesto implementacije mikroračunala. Micro:bit otvara mogućnost razvoja brojnih istraživačkih ideja u nastavi fizike uz relativno male troškove. Upotrebom micro:bit uređaja kao mjernog instrumenta u fizikalnom pokusu, uz mogućnost prikupljanja i bežičnog slanja podataka, učenike uvodimo u istraživački proces. Premda je preciznost mjerenja manja nego s profesionalnom opremom, ona je dovoljna za detekciju i analizu fizikalnih pojava. Micro:bitom izmjereni podaci prenose se na računalo, te se ovisno o razini obrazovanja na kojoj se tema obrađuje, mogu izvoditi jednostavne i složene analize i fizikalna modeliranja. Moglo bi se reći da je micro:bit i prvi korak u smjeru razvoja i dizajna novih uređaja ili visokotehnoloških proizvoda. U obrazovanju 21. stoljeća važno je da se učenici praktično upoznaju s tim procesom. In modern education, the teaching of physics as one of the fundamental STEM areas is of increasing importance. The key questions today are how to actively involve students in the teaching process, increase their interest in physics and encourage them further in the direction of STEM areas that are the backbone of 21st century occupations. The use of microcomputers in teaching has been considered for a long time, but only 5 years ago the construction of a specially designed microcomputer BBC Micro:bit for the needs of education in the European Union led to mass application in schools. In parallel, ideas and methods are being developed on how to include them in the teaching of individual subjects. Teaching physics, which has a physical experiment at its center, is the logical place to implement microcomputers. Micro:bit opens the possibility of developing numerous research ideas in physics teaching at relatively low cost. By using micro:bit as a measuring instrument in a physical experiment with the possibility of collecting and sending data wirelessly, we introduce students to the research process. Although the measurement accuracy is lower than with professional equipment, it is sufficient for the detection and analysis of physical phenomena. Micro:bit-measured data are transferred to a computer and, depending on the level of education at which the topic is covered, simple and complex analyzes and physical modeling can be performed. It could be said that micro:bit is also the first step in the direction of development and design of new devices or high-tech products. In 21st century education, it is important that students become practically familiar with this process.