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A perspective on competitive freeride skiing and snowboarding
No full textFreeride skiing and snowboarding—collectively termed competitive freeriding—have evolved from niche extreme sports into formally recognized disciplines under the International Ski & Snowboard Federation (FIS). Unlike traditional alpine or freestyle events, competitive freeriding emphasizes creative line selection, technical execution, fluidity, style, and aerial maneuvers on natural, ungroomed mountain terrain. Athletes descend complex slopes based solely on visual inspection, without practice runs, facing unique physical and psychological challenges. This perspective article outlines the competition format and judging system, identifies key physiological and biomechanical demands, and reviews essential equipment and safety considerations. Despite growing popularity and institutional recognition, scientific research remains limited—primarily focused on avalanche risk and injury incidence—while other dimensions, such as psychological resilience, creative expression, and environmental connectedness, remain underexplored. Physiologically, competitive freeriders require high levels of eccentric and explosive strength, core stability, reactive control, and anaerobic endurance to navigate variable terrain and absorb impact during aerial maneuvers. Lower-extremity injuries—particularly anterior cruciate ligament (ACL) ruptures—are a major concern. Technological advances in drone-based filming, athlete monitoring, and protective equipment are reshaping freeride competition and broadcasting. As the sport moves toward potential Olympic inclusion, the central challenge lies in embracing innovation without compromising the core values of freedom, improvisation, and connection to the mountain environment
Evolution of microstructure in induction hardened roll from tool steel
No full textValji so ključni in hkrati najranljivejši deli valjarskih linij za hladno valjanje. Pomembno je, da prenesejo dolge valjarske kampanje brez izgube hrapavosti površine ali drugih poškodb. Novo razviti valji so izdelani iz orodnega jekla in imajo veliko hrapavost površine, manjšo obrabo in večjo odpornostjo na poškodbe, pri čemer odpravljajo potrebo po okoljsko škodljivem kromanju, ki je pogosto pri standardnih jeklenih valjih. V okviru doktorskega dela smo raziskovali jeklo z 8-% masnim deležem kroma za uporabo v hladnem valjanju z uporabo različnih tehnik optične in vrstične elektronske mikroskopije, rentgenske difrakcije, meritev trdote in triboloških testov.
Elektroda iz jekla OCR8W je bila naprej elektroobločno pretaljena pod žlindro in nato prekovana v kovano palico premera 325 mm in dolžine 1560 mm, ki je bila nadalje postružena v valj premera 315 mm z dolžino delovne površine 1250 mm ter skupno dolžino 1530 mm. Po poboljšanju, tj. kaljenju in popuščanju valja, smo delovno površino valja postružili na 309 mm in nato valj indukcijsko kalili s štirimi različnimi pomiki (24, 30, 36 in 42 mm/min). Po kaljenju smo ga popuščali najprej pri 515?°C 24 ur, nato pa še dodatnih 24 ur pri 480?°C. Analiza je pokazala jasen vpliv hitrosti pomika med indukcijskim kaljenjem na globino kaljene plasti, velikost karbidov in obrabne lastnosti valja. Z zmanjšanjem pomika na 24 mm/min smo povečali globino kaljenosti s 16 mm (pri 36 mm/min) na 25 mm, kar predstavlja 56,25-odstotno povečanje. To podaljša življenjsko dobo valja brez negativnega vpliva na odpornost proti obrabi in druge ključne parametre. Rentgenska fazna analiza je pokazala, da vzorec vsebuje le 0,4 % zadržane avstenitne faze, kar zmanjšuje tveganje za poškodbe valja med delovanjem v primerjavi s standardnimi vrstami jekel za izdelavo valjev.Rolls are the most critical yet vulnerable parts of cold rolling mills. It is crucial for them to withstand long rolling campaigns without losing surface roughness or incurring damage. The newly developed rolls are made from tool-grade steel with high roughness, lower wear, and high damage resistance. One of the most important advantages is the elimination of the need for chrome plating, which is currently widely used on standard steel rolls but is ecologically harmful. We investigated a type of steel containing 8% chromium for use in cold rolling by conducting light optical microscopy, X-ray diffraction analysis, scanning electron microscopy, energy-dispersive spectroscopy, electron backscatter diffraction, hardness testing, and wear resistance evaluations. In this study, a bar with a diameter of 325 mm was electro-slag remelted and forged, machined to a diameter of 315 mm, and quenched and tempered to simulate industrial roll production. After second machining to diameter of 309 mm, a forged roll was induction heated and hardened at four different feed rates (i.e., 24 mm/min, 30 mm/min, 36 mm/min, and 42 mm/min), tempered at 515°C for 24 hours and again at 480°C for 24 hours, and dissected for in-depth analysis. We identified a clear relationship between the feed rate of the roll during induction hardening and the depth of hardness, the sizes of carbides, and the wear properties of the roll. By reducing the feed rate of the roll through the inductor, we increased the depth of the hardened layer from 16 mm (at a feed rate of 36 mm/min) to 25 mm (at a feed rate of 24 mm/min), which is a 56.25% increase expected to extend the lifespan of the working roll without having negative effects on the wear resistance and other important parameters. XRD analysis showed that the sample had a 0.4% residual austenite, which means it had a significantly lower risk of roll damage during operation than standard steel grades
Association of polymorphisms in MARC1 and PNPLA3 genes with non-alcoholic steatosis in adolescents
No full textNealkoholna zamaščenost jeter (NAFLD) je najpogostejša kronična jetrna bolezen pri otrocih in mladostnikih, pri čemer njeno razširjenost dodatno povečuje globalna epidemija debelosti. Bolezen povečuje tveganje za razvoj resnejših zapletov, kot so nealkoholni steatohepatitis (NASH), fibroza in ciroza. Med ključne dejavnike pri razvoju NAFLD uvrščamo genetsko predispozicijo, pri čemer je polimorfizem PNPLA3 (rs738409) povezan z večjim tveganjem za pojav in napredovanje bolezni, medtem ko polimorfizem MARC1 (rs2642438) kaže zaščitni učinek. Večina obstoječih raziskav je bila izvedena pri odraslih, zato so podatki za pediatrično populacijo omejeni.
Namen magistrske naloge je bil preučiti povezavo med pogostima polimorfizmoma PNPLA3 in MARC1 ter pojavnostjo NAFLD pri mladostnikih. V študijo je bilo vključenih 200 mladostnikov iz Črne gore, starih med 16 in 19 let. Prisotnost NAFLD smo potrdili z ultrazvočno preiskavo. Iz vzorcev polne krvi smo izolirali DNA, izvedli genotipizacijo s pomočjo hidrolizirajočih sond in analizirali povezave z biokemijskimi, antropometričnimi ter kliničnimi kazalniki.
Polimorfizem MARC1 rs2642438 je bil povezan z nižjimi vrednostmi LDL-holesterola v vseh modelih, kar nakazuje zaščitni učinek variantnega alela A. Pri PNPLA3 rs738409 so nosilci variantnega alela G (CG ali GG) imeli nižji HDL-holesterol (dominantni model). V podskupini z NAFLD je bil PNPLA3 rs738409 dodatno povezan z višjim skupnim holesterolom (aditivni in dominantni model). Jetrni encimi in izračunani indeksi (HSI, FLI, PNFI) niso pokazali statistično značilnih povezav. Zaključimo lahko, da genetski dejavniki pomembno vplivajo na presnovne značilnosti, povezane z NAFLD, tudi v mladostniški populaciji Naša študija pa predstavlja pomemben prispevek k razumevanju vloge genetike pri NAFLD v adolescenci in odpira možnosti za nadaljnje raziskave genetskih označevalcev v zgodnjem odkrivanju NAFLD.Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children and adolescents, with its prevalence further amplified by the global obesity epidemic. The disease increases the risk of more serious complications such as non-alcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Among the key factors in the development of NAFLD are genetic predispositions, with the PNPLA3 (rs738409) polymorphism associated with a higher risk of disease onset and progression, whereas the MARC1 (rs2642438) polymorphism appears to have a protective effect. Most existing studies have been conducted in adultsconsequently, data on the pediatric population is limited.
The aim of this Master’s thesis was to investigate the association between common PNPLA3 and MARC1 polymorphisms and the occurrence of NAFLD in adolescents. The study included 200 adolescents from Montenegro, aged 16–19 years. NAFLD was diagnosed by ultrasound examination. DNA was isolated from whole blood samples, genotyping was performed using hydrolysis probes, and associations with biochemical, anthropometric, and clinical parameters were analyzed.
The MARC1 rs2642438 polymorphism was associated with lower LDL-cholesterol levels across all genetic models, suggesting a protective effect of the A allele. For PNPLA3 rs738409, carriers of the G allele (CG or GG) had lower HDL-cholesterol (dominant model). In the subgroup with NAFLD, PNPLA3 rs738409 was additionally associated with higher total cholesterol (additive and dominant models). No statistically significant associations were observed for liver enzymes or calculated indices (HSI, FLI, PNFI).
In conclusion, genetic factors significantly influence metabolic characteristics related to NAFLD in the adolescent population. This study provides an important contribution to understanding the role of genetics in pediatric NAFLD and highlights the need for further research on genetic markers for the early detection of NAFLD
Effect of 3-(pyrrolidine-1-yl)pyridine core structure modifications of new heat shock protein 90 C-terminal domain inhibitors on their anticancer activity
No full textRakava obolenja s svojimi kompleksnimi značilnostmi predstavljajo izziv pri razvoju učinkovitih terapevtskih in diagnostičnih metod. Na tem področju zato v ospredje prihajajo novi multitarčni pristopi, ki vzporedno ciljajo več različnih procesov, vključenih v kancerogenezo. Med njimi je tudi zaviranje proteina toplotnega šoka 90 (Hsp90), ki se vpleta v funkcionalnost več sto onkogenih proteinov in posredno v napredovanje raka. Neuspeh prvih zaviralcev, selektivnih za N-končno domeno Hsp90, je bil povezan s toksičnimi učinki in spodbujanjem odziva toplotnega šoka. Raziskovanje se je zato med drugim preusmerilo tudi v zaviranje Hsp90 preko vezave v C-končno domeno. Ker trenutno na trgu še ni učinkovitih C-končnih zaviralcev, smo se razvoja spojin s tem mehanizmom delovanja lotili tudi v sklopu magistrske naloge.
Pripravili smo knjižnice spojin A, B, C in D. Pri načrtovanju smo si pomagali z dostopnimi informacijami o odnosu med strukturo in delovanjem (SAR), pridobljenimi s pomočjo primerjave z znanimi zaviralci C-končne domene Hsp90, saj strukturni podatki o vezavi zaviralcev v C-končno domeno niso na voljo. Naš namen je bil razširiti SAR novih zaviralcev s 3-(pirolidin-1-il)piridinskim osnovnim skeletom, pri čemer je kot izhodišče pri optimizaciji predstavljala spojina TAK-27, sintetizirana na Fakulteti za farmacijo Univerze v Ljubljani. Z modifikacijami različnih strukturnih elementov smo uspešno sintetizirali 15 končnih spojin, pri katerih smo vpliv strukturnih sprememb na in vitro aktivnost ovrednotili s pomočjo rezultatov testa MTS na celični liniji raka dojke MCF-7.
Ugotovili smo, da imata na delovanje velik vpliv prisotnost in položaj dušika v osrednjem aromatskem obroču, pri čemer se je za najugodnejše izkazalo mesto orto glede na amidni substituent. Pri iskanju optimalne razdalje od amida do bazičnega centra smo v knjižnicah A-C kot najobetavnejši substituent identificirali β-alanin z razdaljo dveh ogljikovih atomov. Pri vplivu konfiguracije na pirolidinskem stereogenem centru se je izkazalo, da je slednji odvisen od substituenta z bazičnim centrom, medtem ko se je za najboljši ogrodni sistem z vidika aktivnosti izkazal benzenov obroč. S spojinami knjižnice D smo želeli ovrednotiti vpliv halogenih interakcij v primerjavi s hidrofobnimi oziroma π-interakcijami. Z zamenjavo 3,4-diklorofenila z naftilom smo pripravili najaktivnejši analog naše serije spojin, spojino 29, s srednjo zaviralno koncentracijo 1,97 ± 0,15 μM na celični liniji raka dojke MCF-7. Spojina TAK-27 kljub temu ostaja najaktivnejši analog iz serije pirolidinskih C-končnih zaviralcev Hsp90, razširjen odnos med strukturo in delovanjem pa predstavlja pomembna izhodišča za nadaljnjo optimizacijo tega razreda spojin.Cancer diseases remains one of the most significant public health challenges due to its complex nature, which hinders the development of effective therapeutic and diagnostic strategies. Novel anticancer drugs aim to target multiple processes involved in carcinogenesis. One promising approach is the inhibition of heat shock protein 90 (Hsp90), which regulates the functionality of hundreds of oncogenic proteins and thereby influences disease progression. However, first-generation N-terminal inhibitors failed due to toxicity and induction of the heat shock response. Consequently, research has shifted toward the less-explored C-terminal domain. Since no effective C-terminal inhibitors are currently available on the market, our aim was to develop novel compounds targeting this site.
We designed and synthesized four libraries of compounds A, B, C, and D, guided by structure–activity relationship (SAR) insights from known C-terminal inhibitors, even though detailed binding information for the C-terminal domain remains unavailable. Our work focused on expanding the SAR of novel inhibitors built around a 3-(pyrrolidine-1-yl)pyridine scaffold. TAK-27, previously synthesized at the Faculty of Pharmacy, University of Ljubljana, served as the starting point for optimization. Structural modifications were introduced at multiple positions, resulting in the successful synthesis of 15 final compounds. Their anticancer activity was evaluated using the MTS assay on the MCF-7 breast cancer cell line.
Our results demonstrate that both the presence and position of nitrogen atoms within the central aromatic ring significantly affect activity, with the ortho position relative to the amide substituent proving most favorable. Optimization of the distance between the amide group and the basic center identified β-alanine (two carbon atoms) as the optimal linker. The stereochemistry of the pyrrolidine center influenced activity in relation to substituents at the basic center, while a benzene ring emerged as the most effective scaffold. In library D, we investigated the role of halogen bonding compared with hydrophobic and π-interactions. Substituting a 3,4-dichlorophenyl group with a naphthyl moiety yielded the most active analogue in our series, compound 29, with a half-maximal inhibitory concentration (IC50) of 1.97 ± 0.15 μM in MCF-7 cells. Nevertheless, TAK-27 remains the most potent pyrrolidine-based C-terminal Hsp90 inhibitor identified to date and represents a strong lead for further optimization
Izboljšanje mehanskih lastnosti Kevlarjevih kompozitov z optimiziranimi parametri šivanja
No full textThe study explores the development of stitched reinforced composites using Kevlar woven fabric as the primary reinforcement. The influence of stitching parameters, stitch type, needle type and stitches per cm (SPC) on the mechanical performance of the composites was systematically investigated. Kevlar fabric was stitched using different needle types and SPC values before being mechanically tested for tensile strength, delamination resistance and impact performance. The results demonstrate that composites stitched with a ballpoint needle using a chain stitch at 3.94 SPC exhibited the highest mechanical strength, with tensile strength increasing from 145 MPa (unstitched) to 191.5 MPa (lock stitch) and 240 MPa (chain stitch). Impact resistance improved from 98 kJ/m² (unstitched) to 133 kJ/m² (ballpoint needle, lock stitch), with chain-stitched composites showing even better performance due to the greater load distribution of the sewing thread and reduced fabric damage. Conversely, lock-stitched composites provided superior delamination resistance due to enhanced interlayer gripping. These findings highlight the potential of the developed composite for advanced protective applications, including bulletproof vests and aerospace structures requiring superior impact resistance and structural integrity.Prispevek obravnava razvoj s šivanjem ojačanih kompozitov, pri katerih je kot primarna ojačitev uporabljena tkanina iz Kevlarja. Sistematično je bil preučen vpliv parametrov šivanja, vrste vboda, vrste igle ter število vbodov na centimeter (SPC) na mehanske lastnosti kompozitov. Kevlar tkanina je bila šivana z različnimi vrstami igel in SPC vrednostmi, preden je bila mehansko testirana na natezno trdnost, odpornost proti razslojevanju in odpornost proti udarnim obremenitvam. Rezultati kažejo, da so kompoziti, šivani z iglo z okroglo konico in verižnim vbodom pri 3,94 SPC, pokazali najvišjo mehansko trdnostnatezna trdnost se je povečala s 145 MPa (nešivani) na 191,5 MPa (prešivni vbod) in 240 MPa (verižni vbod). Odpornost proti udarcem se je izboljšala z 98 kJ/m² (nešivan) na 133 kJ/m² (igla z okroglo konico, prešivni vbod), pri čemer so kompoziti z verižnim vbodom dosegli še boljše lastnosti zaradi porazdelitve obremenitve preko šivalne niti in manjše poškodbe tkanine. Nasprotno pa so kompoziti s prešivnim vbodom zagotavljali boljšo odpornost proti razslojevanju zaradi izboljšane oprijemljivosti med plastmi. Izsledki raziskave poudarjajo potencial razvitega kompozita za napredne zaščitne aplikacije, vključno z neprebojnimi jopiči in letalskimi strukturami, ki zahtevajo visoko odpornost proti udarcem in strukturno celovitost
Effect of confinement geometry on pool boiling performance of gold-coated copper surface
No full textPool boiling is widely employed in compact thermal management systems, but its performance can deteriorate significantly under geometric confinement. This study investigates the combined effects of vertical gap height and confinement plate diameter on pool boiling of distilled water at atmospheric pressure using gold-coated copper samples. The vertical gap between the boiling surface and an overhead plate varied from 0.1λ to 20λ, where λ = 2.5 mm is the capillary length of water, and three plate diameters were examined: 14 mm, 24 mm, and 39 mm. For large gaps (▫▫), the critical heat flux (CHF) remained at approximately 1100 kW m−2 and the heat transfer coefficient (HTC) was comparable to unconfined boiling. As the gap decreases below 2.5λ, both CHF and HTC decrease sharply. At the smallest gap (0.1λ), CHF and HTC were reduced by up to 78 % and 85 %, respectively, relative to the unconfined reference. In the intermediate gap range (0.5λ–2.5λ), the plate diameter had a pronounced effect, with the largest plate producing substantially lower CHF and HTC than the smallest plate for the same gap height due to more restricted radial vapor escape. High-speed visualization confirmed that strong confinement promotes bubble coalescence, vapor accumulation beneath the plate, and intermittent dryout of the boiling surface. Based on the CHF data for all gap heights and plate diameters, empirical correlations were developed using a dimensionless gap ratio and a characteristic plate-size parameter, providing a predictive framework for assessing CHF under combined vertical gap height and confinement plate diameter
Optične sklopne strukture za heterogeno integracijo gradnikov kvantne fotonike
No full textThis thesis belongs to the general field of integrated photonics. In analogy to integrated electronics, integrated photonics offers several benefits over discrete optical assemblies, including small size and robust assembly, highly scalable functionality and complexity, as well as mass manufacturing at a fraction of the cost of bulk optical devices. However, in contrast to electronics, which is dominated by CMOS fabrication of silicon chips, there exist a plethora of photonic integration platforms and technologies based on a variety of materials such as Si, SiN, InP, GaAs, LiNbO3, glass, polymers, and more. This is due to the competing optical and optoelectronic properties of different materials—no single platform has all the capabilities necessary to enable monolithic fabrication of the variety of active and passive photonic components needed in conjunction to form fully featured devices. Hence, heterogeneous integration of diverse components on a single chip is a very active topic in integrated photonics. Besides enabling advances in more traditional application areas such as optical communications, it opens the door to new opportunities also in other areas, including quantum technologies. In this context, the benefits of photonic integration and importance of photons as quantum information carriers makes quantum photonic integrated circuits (QPICs) critical to the development of future scalable quantum technologies. However, to satisfy the stringent requirements of these technologies, diverse materials and photonic platforms must be heterogeneously integrated. Here, a critical limitation of current integration techniques are optical losses associated with the optical coupling of these platforms, which must be minimised.
In this thesis, we focus on design and experimental demonstrations of robust and highly efficient coupling structures used to optically couple heterogeneously integrated quantum photonic devices in QPICs. We particularly focus on the integration of GaAs waveguides with SiN waveguides. The former are used in single-photon sources based on waveguide-embedded InAs quantum dots but suffer from high optical propagation loss. In contrast, the latter are well-known for their low-loss operation and thus present an excellent interposer platform for scalable QPICs. Due to the high losses of GaAs waveguides, which hinder the SiN-GaAs optical coupling efficiency, the research presented in this thesis comes in two parts. First, we systematically investigate the propagation losses of standalone GaAs waveguides to identify their main origins and develop deeper insight into underlying scattering mechanisms. And second, we devise a strategy to design efficient optical couplers for heterogeneous integration considering realistic operating conditions. These conditions include GaAs propagation losses, analysed in the first part of our research, and key structural variations of fabricated devices, which originate from the limitations of current integration techniques.
Our study of scattering propagation losses spans two suspended GaAs platforms operating at wavelengths of 930 nm and 1300 nm, corresponding respectively to an established platform used to fabricate high-quality single-photon sources and an emerging one in the telecommunication O-band. This approach allows us to evaluate and compare scattering losses across both mature and exploratory wavelengths relevant to QPICs. Using a combined approach of numerical simulations and experimental measurements, we examine four key waveguide nano- and micro-scale perturbation types: sidewall roughness, top surface roughness, surface particles, and suspension tethers. We decouple their individual contributions to the total propagation loss by employing the same rigorous numerical method in all cases, enabling a well-founded comparative analysis not found in existing literature. We characterise fabricated PIC samples to determine the statistical properties of waveguide perturbations and to directly measure the total scattering propagation loss, also isolating the loss induced by a single suspension tether.
By correlating experimental data with simulations, we identify sidewall roughness as the dominant source of scattering loss in both platforms, contributing about 3× more in the 930 nm case than in the 1300 nm case. Secondly, we also identify suspension tethers as significant loss contributors, accounting for roughly ⅓ of the losses at 1300 nm and down to ⅙ (due to higher overall losses) at 930 nm. Through additional simulation analyses, we investigate these losses and propose two design-time avenues for loss reduction. We consider the waveguide width dependence of sidewall scattering and link observed local maxima to the occurrence of weakly-guided higher-order modes, which is an insight enabled by our rigorous numerical approach. By selecting wider waveguide widths corresponding to local minima, we show that sidewall scattering losses can be reduced by factors up to 4–5. To address suspension tether losses, we propose a concrete tether geometry optimisation strategy and demonstrate a simulated loss reduction of ~2.5× while maintaining the overall structure layout.
In the second part of our research, we investigate the optimisation of adiabatic taper mode-couplers for high efficiency operation tolerant to fabrication variations and propagation losses. We particularly focus on the integration of the 930 nm suspended GaAs platform with a low-loss SiN interposer through micro-transfer printing (µTP). In this case, the key coupling loss mechanisms are mode coupling and scattering caused by systematic fabrication variations like µTP-induced misalignment and sidewall scattering propagation losses, which are investigated in the scope of the first part of our research. These effects can be minimised by optimising the adiabatic waveguide tapering profile and length. Here, we propose a fully numerical strategy directly incorporating systematic fabrication variations in the taper optimisation procedure based on simulations and a global optimisation algorithm. Moreover, we take a second step and also include sidewall scattering losses determined in the first part of the thesis in the optimisation objective function in addition to losses caused by systematic variations. These are modelled in the same way as in the case of standalone GaAs waveguides and are critically important as they are heavily influenced by the waveguide width variation in the taper. In this way, the optimisation algorithm is guided towards an optimal tapering profile tolerant to explicitly defined variations and propagation losses.
We apply our devised strategy to design two adiabatic SiN-GaAs couplers considering: (1) only systematic variations, and (2) both systematic variations and propagation losses. We verify their performance through experiment (and simulations). Our measurements show increased coupling efficiency in the second case (-0.4 dB) compared to the first (-0.6 dB) and a substantial improvement compared to a reference established semi-analytical coupler design (-1.0 dB).
In relation to propagation losses, our combined simulation and experimental approach provides deeper insight into the underlying scattering loss mechanisms, which remain a fundamental challenge across all photonic integration technologies—including heterogeneous approaches. Our adiabatic coupler design approach builds on this and incorporates a waveguide width dependent propagation loss model in the taper optimisation procedure for the first time to our knowledge. The devised optimisation strategy enables accurate consideration of explicitly defined systematic fabrication variations and propagation losses, substantially improving coupling performance. We apply this strategy to design adiabatic tapers enabling high efficiency coupling between a low-loss SiN platform and a high loss GaAs platform used to fabricate high quality single-photon sources. Therefore, our findings in both parts of our research advance QPICs both at the monolithic and heterogeneous integration levels. First, the proposed improvements of the standalone GaAs platform offer a practical route to significantly reduce propagation losses in suspended GaAs strip waveguides, representing a valuable step toward enabling more complex QPICs directly within the single-photon source host platform. And second, our adiabatic coupler optimisation strategy and concrete SiN-GaAs coupler designs enable improved coupling of heterogeneously integrated single-photon sources and represent a key step forward for robust high-efficiency adiabatic mode-coupler design, supporting heterogeneous integration of diverse QPIC components.Ta doktorska disertacija spada v širše področje integrirane fotonike. Po analogiji z integrirano elektroniko integrirana fotonika ponuja več prednosti v primerjavi z diskretnimi optičnimi sistemi. Te vključujejo manjšo velikost in bolj robusten sklop gradnikov, zelo razširljivo funkcionalnost in kompleksnost sistemov ter množično proizvodnjo ob znatno nižji ceni v primerjavi z diskretnimi optičnimi gradniki. V nasprotju z elektroniko, kjer prevladuje CMOS-proizvodnja silicijevih čipov, pa v fotoniki obstaja množica integracijskih platform in tehnologij, ki temeljijo na različnih materialih, kot so Si, SiN, InP, GaAs, LiNbO₃, steklo, polimeri in še več. To izhaja iz konkurenčnih optičnih in optoelektronskih lastnosti različnih materialov – nobena posamezna platforma ne zagotavlja vseh potrebnih zmogljivosti, ki bi skupaj omogočale monolitno izdelavo raznolikih aktivnih in pasivnih fotonskih komponent, nujnih za proizvodnjo celovitih naprav s široko funkcionalnostjo. Zato je v integrirani fotoniki heterogena integracija raznolikih gradnikov na enem samem čipu zelo aktivna raziskovalna tema. Poleg napredka na bolj tradicionalnih področjih, kot so optične komunikacije, ta odpira tudi nove priložnosti na drugih področjih, med drugim v kvantnih tehnologijah. V tem kontekstu kombinacija prednosti integrirane fotonike in pomena fotonov kot kvantnih nosilcev informacij daje kvantnim fotonskim integriranim vezjem (QPIC) ključno vlogo v razvoju prihodnjih razširljivih kvantnih tehnologij. Vendar pa je za izpolnjevanje strogih zahtev teh tehnologij nujna heterogena integracija različnih materialov in platform integrirane fotonike. Pri tem so ena glavnih omejitev sodobnih integracijskih tehnik optične izgube pri sklopu med platformami, ki jih je treba čim bolj zmanjšati.
V tej disertaciji se osredotočamo na načrtovanje in eksperimentalno demonstracijo robustnih in visoko učinkovitih sklopnih struktur, ki se uporabljajo za optično sklapljanje heterogeno integriranih kvantnih fotonskih gradnikov v QPIC. Posebno se osredotočamo na integracijo valovodov GaAs in valovodov SiN. Prvi (GaAs) se uporabljajo v enofotonskih virih, ki temeljijo na vgrajenih kvantnih pikah InAs, vendar so omejeni z visokimi optičnimi izgubami širjenja svetlobe. Drugi (SiN) so pa znani po nizko-izgubnem delovanju in predstavljajo odlično povezovalno platformo za razširljive QPIC. Zaradi visokih izgub valovodov GaAs, ki zmanjšajo učinkovitost optičnega sklopa SiN–GaAs, so raziskave, predstavljene v tej disertaciji, razdeljene na dva dela. Najprej sistematično preučimo izgube pri širjenju svetlobe v samostojnih valovodih GaAs, da identificiramo njihove glavne izvore in pridobimo globlji vpogled v temeljne sipalne mehanizme. Nato pa razvijemo strategijo za načrtovanje učinkovitih optičnih sklopnikov za heterogeno integracijo ob upoštevanju realnih delovnih pogojev. Ti pogoji vključujejo izgube širjenja v GaAs, preučene v prvem delu raziskav, in ključne strukturne variacije izdelanih naprav, ki izvirajo iz omejitev sodobnih integracijskih postopkov.
Naša študija sipalnih izgub pri širjenju svetlobe zajema dve platformi visečih valovodov GaAs, ki delujeta pri valovnih dolžinah 930 nm in 1300 nm, kar ustreza uveljavljeni platformi za izdelavo visokokakovostnih enofotonskih virov in platformi v razvoju za enofotonske vire v telekomunikacijskem pasu O. Ta pristop nam omogoča evaluacijo in primerjavo sipalnih izgub pri zrelih in eksperimentalnih valovnih dolžinah, pomembnih za QPIC. Z združenim pristopom numeričnih simulacij in eksperimentalnih meritev preučimo štiri ključne nano- in mikro-strukturne vrste perturbacij valovodov: hrapavost stranic, hrapavost zgornje ploskve, površinske delce in nosilne mostičke. Njihove posamezne prispevke k skupnim izgubam širjenja razločimo z uporabo iste rigorozne numerične metode v vseh primerih, kar omogoča dobro utemeljeno primerjalno analizo, kakršne v obstoječi literaturi ni mogoče najti. S karakterizacijo izdelanih vzorcev PIC določimo statistične lastnosti perturbacij valovodov in neposredno izmerimo skupne sipalne izgube širjenja, pri čemer izoliramo tudi izgube, ki jih povzroči posamezen nosilni mostiček.
S korelacijo eksperimentalnih podatkov s simulacijami identificiramo hrapavost stranic valovoda kot dominanten vir sipalnih izgub na obeh platformah, pri čemer ta prispeva približno 3× več pri 930 nm kot pri 1300 nm. Poleg tega identificiramo nosilne mostičke kot pomembne povzročitelje dodatnih izgub, ki predstavljajo približno ⅓ izgub pri 1300 nm in najmanj ⅙ (manjši delež zaradi večjih skupnih izgub) pri 930 nm. Z dodatnimi simulacijskimi analizami te izgube podrobneje preučimo in predlagamo dva pristopa k njihovemu zmanjšanju v fazi načrtovanja PIC. Obravnavamo odvisnost sipanja na stranicah valovoda od njegove širine in opažene lokalne maksimume povežemo s pojavom šibko vodenih višjih rodov, kar je vpogled, omogočen z našim rigoroznim numeričnim pristopom. Z izbiro širših valovodov, ki ustrezajo lokalnim minimumom, pokažemo, da je mogoče sipalne izgube stranic zmanjšati za faktor do 4–5. Za zmanjšanje izgub nosilnih mostičkov pa predlagamo konkretno strategijo optimizacije njihove geometrije in pokažemo simulirano zmanjšanje izgub za ~2,5× brez sprememb topologije strukture.
V drugem delu raziskav obravnavamo optimizacijo adiabatnih zožitvenih sklopnikov za visoko učinkovito delovanje, odporno na variacije pri izdelavi vezij in izgube širjenja. Posebno se osredotočamo na integracijo viseče platforme GaAs 930 nm z nizko-izgubno povezovalno platformo SiN preko mikro-prenosnega tiska (µTP). V tem primeru so ključni mehanizmi izgub pri sklopitvi medrodovno sklapljanje in sipanje svetlobe, ki ga povzročijo sistematične proizvodne variacije, kot je zamik struktur zaradi µTP, ter sipalne izgube stranic valovodov, ki so obravnavane v prvem delu raziskav. Te učinke lahko minimiziramo z optimizacijo profila in dolžine adiabatne zožitve valovoda. Za to predlagamo popolnoma numerično strategijo, ki neposredno vključuje sistematične variacije v postopek optimizacije zožitve na osnovi simulacij in algoritma globalne optimizacije. V nadaljnjem, drugem koraku, v cenovno funkcijo optimizacije vključimo poleg izgub zaradi teh variacij tudi sipalne izgube stranic valovoda, določene v prvem delu disertacije. Te modeliramo na enak način kot pri samostojnih valovodih GaAs v prvem delu raziskav in so ključnega pomena, saj nanje močno vplivajo spremembe širine valovoda vzdolž zožitve. Na ta način optimizacijski algoritem usmerimo proti optimalnemu profilu zožitve, odpornemu na eksplicitno definirane variacije in izgube širjenja.
Našo zasnovano strategijo uporabimo za načrtovanje dveh adiabatnih sklopnikov SiN–GaAs, pri čemer upoštevamo: (1) le sistematične variacije in (2) tako sistematične variacije kot tudi izgube širjenja. Njuno delovanje preverimo z eksperimentom (in simulacijami). Naše meritve pokažejo povečano učinkovitost sklopitve v drugem primeru (-0,4 dB) v primerjavi s prvim (-0,6 dB) ter bistveno izboljšanje v primerjavi z referenčnim uveljavljenim semi-analitično zasnovanim sklopnikom (-1,0 dB).
V povezavi z izgubami širjenja naš kombiniran pristop simulacij in eksperimenta ponuja globlji vpogled v osnovne mehanizme sipalnih izgub, ki ostajajo temeljni izziv v vseh tehnologijah fotonske integracije – tudi v heterogenih pristopih. Naš pristop k načrtovanju adiabatnih sklopnikov temelji na tem in v postopek optimizacije zožitve vključi model izgub širjenja z odvisnostjo od širine valovoda, kar je po naših informacijah prvi tovrsten pristop. Razvita optimizacijska strategija omogoča natančno upoštevanje eksplicitno definiranih sistematičnih proizvodnih variacij in izgub širjenja, kar bistveno izboljša učinkovitost in zanesljivost sklopitve. To strategijo uporabimo za načrtovanje adiabatnih zožitev, ki omogočajo visoko učinkovito sklapljanje med nizko-izgubno platformo SiN in visoko-izgubno platformo GaAs, uporabljeno za izdelavo visokokakovostnih enofotonskih virov. Naše ugotovitve v obeh delih raziskav prispevajo k napredku QPIC tako na monolitni kot tudi na heterogeni ravni. Predlagane izboljšave samostojne platforme GaAs ponujajo praktično pot k znatnemu zmanjšanju izgub pri širjenju svetlobe v visečih valovodih GaAs, kar predstavlja pomemben korak k omogočanju bolj kompleksnih QPIC neposredno na gostiteljski platformi enofotonskih virov. Hkrati pa naša strategija za optimizacijo adiabatnih sklopnikov ter konkretni načrti sklopnikov SiN–GaAs omogočajo izboljšano sklapljanje heterogeno integriranih enofotonskih virov in predstavljajo ključen korak naprej za načrtovanje robustnih in visoko učinkovitih adiabatnih zožitvenih sklopnikov za heterogeno integracijo raznolikih gradnikov QPIC
Germanizmi v romanu Danila Kiša „Vrt, pepel" in njihova raba v sodobnem črnogorskem jeziku
No full textDie vorliegende Arbeit beschäftigt sich mit Germanismen, die im Roman „Garten, Asche“ von Danilo Kiš vorkommen. Das Ziel der Korpusanalyse ist es, die im Roman vorkommenden Germanismen zu identifizieren und ihren Kontext zu analysieren. Ergänzend wird mithilfe eines Sprachtests unter Sprachbenutzer/-innen verschiedener Generationen ihr Gebrauch in der gegenwärtigen montenegrinischen Sprache analysiert. Im theoretischen Teil der Arbeit konzentriere ich mich auf die Definition von Germanismen und auf das Leben und Werk des Autors, um den kulturellen und historischen Hintergrund des Gebrauchs von Germanismen im Werk zu beleuchten. Der praktische Teil stellt eine Untersuchung vor, die darauf abzielt, den Gebrauch der im Werk identifizierten Germanismen in der gegenwärtigen montenegrinischen Sprache zu analysieren.Magistrsko delo obravnava germanizme, ki se poljavljajo v romanu Danila Kiša „Vrt, pepel“. Cilj korpusne analize je identificirati germanizme, ki se poljavljajo v romanu, in analizirati njihov kontekst. Poleg tega je za analizo njihove rabe v sodobnem črnogorskem jeziku uporabljen jezikovni test med jezikovnimi uporabniki različnih generacij. V teoretičnem delu diplomskega dela se osredotočam na opredelitev germanizmov ter na avtorjevo življenje in delo, da bi osvetlila kulturnozgodovinsko ozadje rabe germanizmov v delu. V praktičnem delu je predstavljena raziskava, katere namen je analizirati rabo germanizmov, opredeljenih v delu, v sodobnem črnogorskem jeziku
Contextual reflection of emergence of Slovenian fashion
No full textV doktorski nalogi so obravnavani različni konteksti pojavnosti slovenske mode od leta 1945 do leta 2024. Slovensko modo analiziramo v časovnem pregledu, geografski specifiki, v okviru političnih sprememb, pod vplivi ekonomskih dejavnikov, znotraj družbenih okoliščin, v relaciji do kulturnih vplivov in trajnostnih globalnih zahtev. Kvalitativna analiza zbranih podatkov o slovenski modi ponuja celovit vpogled v njeno specifičnost v zgodovinskih refleksijah, ki so bile za potrebe raziskave razdeljene v sedem obdobij: proizvodnja od leta 1900 do 1945, nastanek oblačilne industrije po letu 1945, strukturne spremembe v 60. letih 20. stoletja, razcvet oblačilne industrije v 70. letih 20. stoletja, nestabilne razmere v 80. letih 20. stoletja, pojav samostojnih modnih oblikovalcev po letu 1990 in vključevanje trajnostnih praks v 21. stoletju. Znotraj zgodovinskih obdobij smo preverili in analizirali vplive ugotovljenih sprememb parametrov v kontekstualnih refleksijah pojavnosti mode in oblačilne kulture v Sloveniji. Opredelili smo ključne dejavnike v različnih obdobjih, ki so vplivali na pojavnost slovenske mode, določili parametre družbenega, kulturnega, gospodarskega in političnega okolja, ki so vplivali na razvoj slovenske mode, ter ovrednotili parametre časovnega, geografskega in trajnostnega konteksta pojavnosti slovenske mode. Z analizo in primerjavo raznolikih kontekstov smo ugotavljali pomen in umestitev slovenske mode v relaciji do globalnih dejavnikov in trendov.In the doctoral thesis, the different contexts of the appearance of Slovenian fashion from 1945 to 2024 are discussed. Slovenian fashion is analyzed in terms of time, in geographical specifics, in the context of political changes, under the influence of economic factors, within social circumstances, in relation to cultural influences and sustainable global demands. Qualitative analysis of collected data on Slovenian fashion offers a comprehensive insight into its specificity in historical reflections, which were divided into seven periods for the purposes of the research: manufacturing production from 1900 to 1945, the emergence of the clothing industry after 1945, structural changes in the 1960s, the boom of the clothing industry in the 1970s, unstable conditions in the 1980s. century, the emergence of independent fashion designers after 1990 and the incorporation of sustainable practices in the 21st century. Within historical periods, we verified and analyzed the impacts of identified parameter changes in contextual reflections of the appearance of fashion and clothing culture in Slovenia. We identified the key factors in different periods that influenced the emergence of Slovenian fashion, determined the parameters of the social, cultural, economic and political environment that influenced the development of Slovenian fashion and evaluated the parameters of the temporal, geographical and sustainable context of the emergence of Slovenian fashion. By analyzing and comparing various contexts, we determined the importance and placement of Slovenian fashion in relation to global factors and trends
Strong log-convexity of genus sequences
No full textFor a graph , and a nonnegative integer , let be the number of -cell embeddings of ▫▫ in an orientable surface of genus (counted up to the combinatorial homeomorphism equivalence). In 1989, Gross, Robbins, and Tucker [Genus distributions for bouquets of circles, J. Combin. Theory Ser. B 47 (1989), 292-306] proposed a conjecture that the sequence is log-concave for every graph . This conjecture is reminiscent to the Heron-Rota-Welsh Log Concavity Conjecture that was recently resolved in the affirmative by June Huh et al., except that it is closer to the notion of -matroids than to the usual matroids. In this short paper, we disprove the Log Concavity Conjecture of Gross, Robbins, and Tucker by providing examples that show strong deviation from log-concavity at multiple terms of their genus sequences