Hrčak - Portal of scientific journals of Croatia
Not a member yet
321498 research outputs found
Sort by
Enhancing Trust by Ensuring Fairness in Medical AI
No full textRad se bavi suvremenim izazovima pravednosti u kontekstu primjene umjetne inteligencije (UI) u zdravstvenoj skrbi. Osim izazova konceptualizacije pravednosti, prikazana je i važnost objašnjivosti i objašnjive umjetne inteligencije putem koje se osigurava povjerenje u primjenu UI u zdravstvu. Neželjeni primjeri primjene UI u zdravstvu podsjećaju da je moguće da sustav UI predlože nepravedne i pristrane ishode predviđanja koja mogu dodatno produbiti društvene nejednakosti na rasnoj, etničkoj ili drugim pripadnostima. Potrebno je stoga razvijati sustave UI koji će ublažavati pristranost i posljedice diskriminacije koji mogu nepovoljno utjecati na procese donošenja odluka. Usprkos alatima poput »AI Fairness 360« i »What-If Tool« koji pružaju tehnička rješenja za smanjenje pristranosti u sustavima UI, potrebno je uložiti dodatan napor u razvoj UI koja pruža mogućnost objašnjenja uz ispunjenje etičkih normi. Stoga se rješenje za ublažavanje nepravednosti i pristranosti može naći u sustavu UI pod nazivom TWIX koji, zahvaljujući mogućnostima objašnjivosti, osigurava pravednija predviđanja. Buduća istraživanja trebala bi biti usmjerena u razvoj sličnih sustava UI s mogućnostima objašnjenja predviđanja radi pravednijega donošenja odluka.The paper addresses current issues of fairness in context of the application of artificial intelligence (henceforth: AI) in healthcare. Along with the difficulties in conceiving fairness, paper demonstrates the significance of explainable AI (henceforth: xAI), since xAI helps to mitigate bias and build trust in the use of Medical AI. Case studies of AI's use in healthcare serve as a reminder that an AI system may produce unfair and biased prediction results, which might exacerbate societal disparities based on race, ethnic, or other factors. Thus, AI systems that will mitigate bias and minimaze effects of discrimination—which can negatively impact on the decision-making process—must be developed. Even with technological solutions for reducing bias in AI systems, such as the What-If Tool and AI Fairness 360, additional effort is required to create AI that can provide explanations for its predictions in order to adhere to the ethical norms. Furthermore, explainability is especially important for healthcare in situations requiring informed consent. This was highlighted in the most recent Artificial Intelligence Act regulation, which placed a strong emphasis on explainability, transparency, and human oversight. This paper presents technical solutions that can significantly reduce bias by enabling explainable predictions, which positively impacts clinical outcomes and trust in the technology. Proposal for the development of AI systems like TWIX, which improve trust and mitigate bias by providing explanations, we can contribute to the development of future AI systems that are trustworthy and ethical. Therefore, I think that an AI system named TWIX, which guarantees the fairness of predictions due to its explainability capabilities, offers ways to reduce bias and discrimination. Future research should focus on developing similar AI systems with predictive explanatory abilities in order to promote fair and trustworthy decision-making
Iskorištavanje metaheuristički optimizirane iskoristivosti klasifikatora za otkrivanje i razumijevanje ispisivanja studenata
No full textEducation is crucial for social progress, fostering knowledge, skills, and cognitive development, and is closely linked to long-term economic growth. By enhancing the general knowledge and skills of the population, education fuels innovation and the adoption of new ideas, making human capital a key driver of economic development. A well-educated workforce significantly contributes to research and development, integrating innovations into production and promoting economic growth. Despite extensive research, maintaining high enrolment and low dropout rates remains challenging. The potential of artificial intelligence (AI) in addressing this issue is underexplored. This work aims to fill this gap by leveraging metaheuristic optimized deep neural networks to detect students at risk of dropping out. A modified version of the firefly algorithm (FA) is introduced specifically to meet the demands of this optimization. Additionally, explainable AI (XAI) techniques are employed to better understand the factors influencing student decisions, thereby aiding in the formulation of effective retention policies. The introduced methodology is evaluated on a realworld dataset, with the best models achieving an accuracy exceeding 82% for dropout detection.Obrazovanje je ključno za društveni napredak, poticanje znanja, vještina i kognitivnoga razvoja te je usko povezano s dugoročnim ekonomskim rastom. Povećanjem općega znanja i vještina stanovništva, obrazovanje potiče inovacije i usvajanje novih ideja, čineći ljudski kapital ključnim pokretačem gospodarskoga razvoja. Dobro obrazovana radna snaga značajno doprinosi istraživanju i razvoju, integrirajući inovacije u proizvodne procese i potičući ekonomski rast. Unatoč opsežnim istraživanjima, održavanje visoke stope upisa i niske stope ispisivanja studenata ostaje izazov. Potencijal umjetne inteligencije (AI) u rješavanju ovoga problema još uvijek nije dovoljno istražen. Ovim radom nastoji se popuniti ta praznina koristeći metaheuristički optimizirane duboke neuronske mreže za otkrivanje studenata koji su u riziku od ispisivanja. U tu svrhu, predstavljena je modificirana verzija algoritma krijesnica (FA) kako bi se zadovoljili specifični zahtjevi optimizacije. Dodatno, tehnike objašnjive umjetne inteligencije (XAI) koriste se za bolje razumijevanje čimbenika koji utječu na odluke studenata, čime se olakšava formuliranje učinkovitih strategija zadržavanja studenata. Predložena metodologija evaluirana je na stvarnom skupu podataka, pri čemu su najbolji modeli postigli točnost veću od 82 % u predviđanju ispisivanja studenata
Učinci metode obrnute učionice i korištenja mobitela u nastavi tjelesnoga odgoja
No full textThis pedagogical experiment has been aimed at evaluating the way of preparing Physical Education classes in elementary school. The effects of two methods were compared, one of which is flipped classroom, and the other one is traditional teaching. The flipped classroom method implies prior familiarization of the students with basic information about the content of the next lesson by viewing the video materials that the teacher sends to them via mobile phone. An experiment with two groups was conducted on a sample of 40 elementary school students aged 11 years (±6 months). The experimental group was formed with 21 participants (11 boys and 10 girls) and the flipped classroom method was implemented with them. The control group consisted of 19 participants (10 boys and 9 girls), and their classes were organized in a traditional manner. The experiment lasted eight weeks, during which 16 lessons lasting 45 minutes each were conducted. Elements of handball were practiced in all classes. The learning outcomes were evaluated on the basis of the participants’ grades for six elements: ball catching, passing, dribbling, defensive stance, side shot (chasse) and long jump shot. The effects of the flipped classroom were also evaluated based on the attitudes towards physical education that the participants expressed before and after the experiment, as well as the active workout time in the main part of lesson. The benefits of the flipped classroom in Physical Education, which were explained in previous studies, were confirmed. It has been proved that this method is more effective than traditional teaching. The subjects in the experimental group made significantly more progress in four handball elements. After the treatment, the experimental group had significantly more positive attitudes towards Physical Education than the control group. It was shown that the effects of the flipped classroom depend on the difficulty of the motor tasks being learned, because in more difficult elements this method did not show an advantage compared to traditional teaching. The greatest effects of the flipped classroom were achieved with tasks of moderate difficulty that are aligned with the developmental level of students’ motor skills. The obtained results show that the flipped classroom method can provide a significant contribution to the improvement of Physical Education teaching in elementary school.Ovaj pedagoški eksperiment imao je za cilj vrednovanje načina pripremanja nastave tjelesnoga odgoja u osnovnoj školi. Uspoređeni su učinci dviju metoda, od kojih je jedna obrnuta učionica, a druga tradicionalna nastava. Obrnuta učionica podrazumijeva prethodno upoznavanje učenika s osnovnim informacijama o sadržaju sljedeće lekcije gledanjem videomaterijala koje im nastavnik šalje putem mobitela. Na uzorku od 40 učenika osnovne škole u dobi od 11 godina (±6 mjeseci) proveden je eksperiment s dvije skupine. Eksperimentalnu je činio 21 ispitanik (11 dječaka i 10 djevojčica) i s njima je provedena obrnuta učionica. Kontrolnu skupinu činilo je 19 ispitanika (10 dječaka i 9 djevojčica), a nastava im je bila organizirana na tradicionalan način. Eksperiment je trajao osam tjedana tijekom kojih je provedeno 16 sati po 45 minuta. Na svim satima uvježbavani su elementi rukometa. Ishodi učenja vrednovani su na temelju ocjena koje su sudionici dobili za šest elemenata: hvatanje, dodavanje, vođenje lopte, obrambeni stav, bočni šut (šase) i skok šut u dalj. Učinci obrnute učionice procijenjeni su i na temelju stavova prema tjelesnom odgoju koje su ispitanici izrazili prije i nakon eksperimenta, kao i vremena aktivnoga vježbanja u glavnom dijelu sata. Potvrđene su prednosti obrnute učionice u nastavi tjelesnoga odgoja koji su objašnjeni u prijašnjim studijama. Dokazano je da je ova metoda učinkovitija od tradicionalne nastave. Ispitanici eksperimentalne skupine značajno više su napredovali u četirima rukometnim elementima. Nakon primjene metode obrnute učionice eksperimentalna skupina imala je signifikantno pozitivnije stavove prema tjelesnom odgoju od kontrolne. U eksperimentalnoj skupini izmjereno je duže aktivno vrijeme vježbanja u glavnom dijelu sata. Pokazalo se da učinci obrnute učionice ovise o težini motoričkih zadataka koji se uče jer u težim elementima ova metoda nije pokazala prednost u odnosu na tradicionalnu nastavu. Najveći učinci obrnute učionice postignuti su u zadatcima koji su usklađeni s razvojnom razinom motoričkih sposobnosti učenika. Rezultati pokazuju da metoda obrnute učionice može dati značajan doprinos unaprjeđenju nastave tjelesnoga odgoja u osnovnoj školi
Investigation of the mechanical strength of cement mortars containing novel synthesised chitosan/hydromagnesite stromatolite nano-composite
Get PDFOvaj rad predstavlja upotrebu novog sintetiziranog nanokompozita kitozan/hidromagnezit stromatolit (CHT/HS) u cementnim mortovima i istražuje njegove učinke na mehanička svojstva. Predloženi biološki nanokompozit sintetiziran je metodom „zelene“ sonikacije primjenjujući hidromagnezit stromatolit (HS) iz jezera Salda (Burdur, Turska). Određena su kemijska i morfološka svojstva nanokompozita HS i CHT/HS. Uzorci koji sadrže HS u omjerima od 5 i 10 % i nanostrukture CHT/HS s 0,1, 0,5, 1 i 2 % ispitani su na savojnu i tlačnu čvrstoću nakon 7 i 28 dana. Novi sintetizirani nanokompozit CHT/HS pokazao je jasno povećanje mehaničke čvrstoće. Navedeni rezultati predlažu smjernice za budući rad na različitim primjenama nanopunila.This study introduces the use of a novel synthesised chitosan/hydromagnesite stromatolite (CHT/HS) nano-composite in cement mortars and investigates its effects on the mechanical properties. The proposed bio-based nano-composite was synthesised by a green sonication method using HS originating from Salda Lake (Burdur, Turkey). The chemical and morphological properties of HS and CHT/HS nano-composites were determined. Specimens including HS in ratios of 5 and 10 % and CHT/HS nanostructures with 0.1, 0.5, 1 and 2 % were tested for flexural and compressive strengths for 7 and 28 days. The novel synthesised CHT/HS nano-composite showed a clear enhancement in mechanical strength. These findings suggest directions for future work on different nano-filler applications
Extended developmental plasticity and vulnerability of human prefrontal microcircuits
No full textThe transition from childhood to adulthood has become increasingly prolonged, with milestones such as completing education, marriage, and parenthood occurring later than ever before. This shift raises the question of whether adolescence should still be defined as the period between ages 12 and 18 or if its endpoint should be extended. Neurobiological research revealed that synaptic overproduction and developmental remodeling, including substantial elimination of synaptic spines, continue deeply into the third decade of life before stabilizing at adult level (Petanjek et al. 2023). A recent study performing cross-species proteomic mapping of synapse development, tracked changes in over 1,000 postsynaptic density proteins from midgestation to young adulthood comparing human, macaque and mouse neocortex (Wang et al. 2023.). The results showed that human postsynaptic densities develop two to three times more slowly than those of other species, largely due to a higher abundance of RhoGEF proteins in the turquoise module. The turquoise module is linked to synaptic plasticity, human cognitive function and neuropsychiatric disorders. Overexpression of RhoGEFs was found to increase spine density and delay synapse maturation. Several studies have previously demonstrated that gene expression changes during postnatal brain development in the human prefrontal cortex occur significantly later than in chimpanzees and rhesus macaques (Petanjek et al. 2023). The microcircuits responsible for processing the higher cognitive functions have the most extended period of synaptic overproduction, supporting high plasticity, which is crucial for acquiring complex cognitive abilities, including affective modulation of emotional cues, self-conceptualization, mentalization, cognitive flexibility, working memory and social skills. However, this prolonged development also extends the window of vulnerability, potentially increasing susceptibility to factors that may disrupt the formation of neural circuits involved in higher cognitive functions, which are impaired in neuropsychiatric disorders such as autism and schizophrenia (Petanjek et al. 2023). A recent study performing single-nucleus RNA sequencing (Batiuk et al. 2022), found a reduction in GABAergic neurons and a concomitant increase in principal neurons within dorsolateral prefrontal cortex of patients with schizophrenia. The most pronounced changes were observed in the upper cortical layers, suggesting selective vulnerability and general cortico-cortical network impairment as a core substrate associated with schizophrenia symptomatology. The dopamine system, whose disruption is considered to be one of the key features in schizophrenia, undergoes delayed maturation and changes throughout the whole stage of adolescence. Dopamine maturation interacts with changes in endocannabinoid signaling (Peters and Naneix 2022), characterized by transient increases in receptors expression and gradual rise in neurotransmitter levels. These changes enhance the recruitment of GABAergic interneurons and sustain the activity of pyramidal neurons. Prefrontal dopamine signaling refines processing by improving the selection of specific inputs, decreasing the signal-to-noise ratio, most likely through regulation of glutamatergic synaptic spine pruning. Similar adolescent remodeling hasn’t been observed in other neuromodulatory systems. Given their interactions with different neuronal populations and effects at different synaptic sites, dopamine and endocannabinoid signaling play a critical role in the late maturation of prefrontal circuits and their functioning. Extensive reports showed that external factors, including drug use, nutritional habits, and stress, affect the functioning of the prefrontal cortex during adolescence. Research strongly indicates that these factors interfere with the development of dopamine and endocannabinoid pathways, ultimately impacting the reorganization of cortical microcircuits. A recent epidemiological study conducted on a large Danish cohort found an association between cannabis use disorders and the onset of schizophrenia (Hjorthøj et al. 2023). The study indicated that 15-30% of schizophrenia cases in males, and 5-10% in females could potentially be prevented if cannabis use disorders were avoided between ages 15 and 25. This provides a very explicit example of how the adolescent and post-adolescent brain remains extremely plastic and vulnerable to external factors. Recognizing the extended developmental window in humans is crucial, as it entails both increased plasticity and vulnerability of prefrontal microcircuits. The influence of environmental factors on the shaping of these microcircuits is significant and may contribute to the development of late-onset neuropsychiatric disorders. Insights into prolonged neurodevelopment should be carefully considered when designing psychological, social, and educational strategies for adolescents and young adults, with a particular focus on legislation affecting those under 25
The role of the extracellular matrix in neurodevelopmental brain disorders: a genetic perspective
No full textThe fetal cerebral wall is rich in extracellular matrix molecules (ECM) that fill the intercellular space, estimated to comprise up to 60% of the volume of the early fetal brain. Four numerous families of ECM molecules (hyaluronan, proteoglycans, glycoproteins, and link proteins) are the main components of the biochemical niches that mediate the distribution of key signaling and trophic factors during prenatal development and build mechanical scaffolds to conduct actively morphogenetic processes such as cell proliferation, migration, axon pathfinding, and cortical folding. The transient fetal zones, such as the marginal zone, subplate, and early intermediate zone, are rich in hydrated extracellular matrix (ECM), and the last two are the bases of the cortical (hyperintensity) pattern on MRI scans, highlighting the importance of ECM in brain diagnostic and prognostic MRI follow-up in fetuses. In collaboration with their receptor, the ECM components also play a significant role in the differentiation of dendrites and the genesis of spines and synapses. Finally, some ECM molecules become integral to the quadripartite synapse and perineuronal nets, contributing to the formation of the functional connectome. Humans have more ECM in the cortical wall during fetal development compared to the evolutionary closest primate species. This supports the ECM as an evolutionary force, in conjunction with prolonged brain development, which facilitates the formation of more synapses and more elaborate, complex connections, while also being an additional substrate for vulnerability and plasticity in humans. Mutation of ECM coding genes or dysregulations of the ECM molecules’ expression spatial and temporal patterns, can affect the processes of cell proliferation, migration, cortical folding, or differentiation, leading to a heterogeneous group of disorders- known as malformations of cortical development (MCD, such as microcephalia, megalocephalia, lissencephaly, polymicrogyria, periventricular nodular or subcortical band heterotopia), or neurodevelopmental disorders (NDD), such as epilepsy, autism spectrum (AS), schizophrenia, and/or intellectual disabilities (ID). With the latest advances in sequencing technologies, greater accessibility to whole-genome and whole-exome sequencing (WGS, WES) for diagnostic purposes has led to an increase in the number of mutated genes coding for ECM components identified in patients and linked to MCD or NDD. A few examples include mutations in the heparan sulfate proteoglycan 2 (HSPG2) and laminin subunit gamma 1 (LAMC1) genes, which are associated with disrupted proliferation in the ventricular and subventricular zones, leading to microcephaly, hemimegalencephaly, or focal cortical dysplasia. The mutations in genes coding glycoprotein reelin, ECM glycosylation enzymes, O-mannosyltransferase enzyme, and glycosyltransferase-like protein, or the adhesion G—protein-coupled receptor (RELN, POMT1, LARGE, and GPR56, respectively), have been found to hinder migration and cell adhesion, causing lissencephaly or cobblestone lissencephaly, bilateral frontoparietal polymicrogyria, or ID. Proteoglycans, including versican, neurocan, lumican, hyaluronan, and proteoglycan link protein-1, as well as collagens (encoded by VCAN, NCAN, LUM, HAPLN1, and COL4A1, respectively), are expressed in the subplate and marginal zone. When mutated or dysregulated, these proteins alter synaptogenesis and gyrification, resulting in MCD or ID. The genes PAX6, TBR1, SOX2, and MEF2C coding for transcription factors, as well as members of the Wnt and Notch signaling pathways, enzymes involved in DNA methylation and histone modifications, and miRNAs, regulate the quantity and distribution of the ECM and their dysregulation can be part of the pathogenesis of MCD and NDD. For example, the NDST1 and CHSY1 genes, which encode enzymes involved in ECM biosynthesis, are found to be mutated in patients with AS and IP (for additional examples, see Table 1). The new research paradigm, which leverages the potential of generating induced pluripotent stem cells from patients with MCD or NDD to cultivate cerebral organoids, is an exceptional tool for elucidating the function of ECM and its receptor genes in the developing brain, both in health and disease. Therefore, knowledge of the genetic basis of brain-specific ECM and its MRI representation contributes to understanding the pathogenesis of cortical malformations and brain function abnormalities, and has proven essential in identifying potential new targets for diagnostic and therapeutic approaches to treating neurodevelopmental disorders
Možemo li početnim programima društvenih plesova, latinskoameričkim i standardnim plesovima utjecati na čimbenike rizika za kardiovaskularne bolesti?
No full textCilj istraživanja bio je utvrditi učinak programa standardnih i latinskoameričkih društvenih plesova na
ukupno smanjenje više kardiovaskularnih čimbenika rizika u prethodno sedentarnih osoba odrasle dobi.
U istraživanju je sudjelovalo 100 ispitanika, podijeljenih u eksperimentalnu (N=50) i kontrolnu (N=50) skupinu. Ispitanici oba spola, starosti od 35 do 70 godina, uključeni su prema kriteriju sedentarnosti. Mjerenje rizičnih čimbenika za kardiovaskularne bolesti (anamnestičkih podataka prikupljenih upitnikom, vrijednosti krvnog tlaka, antropometrijskih mjera i krvnih pretraga) provodilo se u obje skupine na početku istraživanja i nakon dva mjeseca. Inicijalna i završna mjerenja kod eksperimentalne skupine provodio je jedan istraživač u plesnim centrima u kojima su ispitanici plesali, dok su se mjerenja kontrolne skupine provodila u ambulantama pod nadzorom liječnika. Eksperimentalna skupina sudjelovala je u dvomjesečnom programu početnog tečaja latinskoameričkih i standardnih društvenih plesova (Cha Cha Cha, Samba, Rumba, Jive,
Bečki valcer, Engleski valcer, Tango i Foxtrot), koji se provodio dva puta tjedno u trajanju od 90 minuta. U
istraživanju je postavljena hipoteza: kardiovaskularni rizični čimbenici značajno su manji u istraživanoj skupini u odnosu na kontrolnu skupinu nakon dva mjeseca treninga plesa. Hipoteza o značajnom smanjenju kardiovaskularnih rizičnih čimbenika u istraživanoj skupini nakon dva mjeseca treninga plesa djelomično je potvrđena jer su smanjenja utvrđena u vrijednostima ukupnog kolesterola (p=0,000) i glukoze (p=0,000). Rezultati binarne logističke regresije pokazali su da kontrolna skupina ima 2,76 puta veću vjerojatnost povećanja indeksa tjelesne mase, OR=2,76, (95%, 1,19-6,42, p=0,019), 6,29 puta veću vjerojatnost povećanja kolesterola, OR=6,29, (95 %, 2,58-15,36,
Hrvatski frazemi kojima se opisuje govorni proces: aspekti frazeološke i međujezične kompetencije studenata
No full textThe conducted research provided insight into specific segments of the phraseological competence of the younger generation of native speakers, which refers to the recognition and use of Croatian idioms that describe the speech process, as well as the knowledge of English equivalents. The results of the research showed a significant disparity between the knowledge of idioms and the self-assessment of their use in the language, which indicates that certain idioms are slowly disappearing from the speech of young people (Hansdóttir, 2024). Although the younger generation of speakers did not show a high level of interlingual phraseological competence regarding this semantic group of idioms, they simultaneously represent a valuable source of additional interpretations of the meaning of idioms, and a relevant reflection of contemporary language use which is not represented in phraseological sources. The paper aims to encourage further empirical and corpus-based research on the knowledge and active use of a broader range of idioms, both in native and foreign languages, to gain deeper and more relevant insights into the phraseological competence of the younger generation of speakers.Provedeno istraživanje pružilo je uvid u pojedine segmente frazeološke kompetencije mlađe generacije izvornih govornika u vezi s poznavanjem i upotrebom hrvatskih idioma kojima se opisuje govorni proces te poznavanjem engleskih ekvivalenata. Rezultati istraživanja pokazali su značajan nesrazmjer između poznavanja idioma i samoprocjene njihove upotrebe u jeziku, što upućuje na činjenicu da pojedini idiomi polako nestaju iz govora mladih (Hansdóttir, 2024). Iako mlađe generacije govornika nisu pokazale visoku razinu međujezične frazeološke kompetencije unutar ove semantičke skupine frazema, ti govornici istovremeno predstavljaju dragocjen izvor dodatnih interpretacija značenja frazema i relevantan su odraz suvremene jezične upotrebe koja nije zastupljena u frazeografskim izvorima. Rad ima cilj potaknuti daljnja empirijska i korpusna istraživanja poznavanja i aktivne upotrebe šireg opusa frazema kako u materinjem, tako i u stranome jeziku, kako bi se dobio relevantniji uvid u razinu frazeološke kompetencije mlađe generacije govornika