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OSA Treatment Lowers the Risk of Declining Daily Activities
No full textAbstract
Background:
The aim of the study was to investigate whether severe obstructive sleep apnea (OSA) had association with quality of life (QOL), fatigue and functional ability seven years after ischemic stroke.
Methods:
A total of 204 ischemic stroke patients were included in the study during 2013‐2015. After seven years the 136 survivors had a structured interview by telephone focusing on subjective QOL, functional ability, fatigue, depression, and insomnia.
Results:
Of alive patients, 136/99.3% answered the questionnaires. The mean age was 64.2 years, 41.9 % were men, and 54/40% had respiratory event index (REI) ≥30/h. Those with REI ≥ 30 were more obese (29.2% vs 26.6%, p < 0.001), and coronary artery disease (25.9% vs 12.2%, p = 0.04), had lower Barthel Index (BI) (88.3 vs 92.3, p = 0.014), higher modified Rankin Scale (mRS) (2 vs 1, p = 0.025), and more need of medical aids (18.4 vs 13.2, p = 0.004). The QOL was good, but lower (6.98 vs 6.48, p = 0.056) and mobility domain was significantly worse (1.5 vs 1.3, p = 0.019) among severe OSA (REI) ≥30/h) patients. The CPAP treatment associated with an impaired risk of decreased usual activities (OR 0.190, 95% CI 0.042‐0.857, p = 0.031). Though severe OSA was not an independent risk factor for functional ability, whereas higher BMI was an independent risk factor for impaired QOL (p = 0.006, 95%CI 1.047‐1.315).
Conclusions:
Seven years post-stroke the QOL was in good level, although it tended to be lower in stroke patients with severe OSA. The CPAP treatment associated with better usual activities in patients with severe OSA.Abstract
Background:
The aim of the study was to investigate whether severe obstructive sleep apnea (OSA) had association with quality of life (QOL), fatigue and functional ability seven years after ischemic stroke.
Methods:
A total of 204 ischemic stroke patients were included in the study during 2013‐2015. After seven years the 136 survivors had a structured interview by telephone focusing on subjective QOL, functional ability, fatigue, depression, and insomnia.
Results:
Of alive patients, 136/99.3% answered the questionnaires. The mean age was 64.2 years, 41.9 % were men, and 54/40% had respiratory event index (REI) ≥30/h. Those with REI ≥ 30 were more obese (29.2% vs 26.6%, p < 0.001), and coronary artery disease (25.9% vs 12.2%, p = 0.04), had lower Barthel Index (BI) (88.3 vs 92.3, p = 0.014), higher modified Rankin Scale (mRS) (2 vs 1, p = 0.025), and more need of medical aids (18.4 vs 13.2, p = 0.004). The QOL was good, but lower (6.98 vs 6.48, p = 0.056) and mobility domain was significantly worse (1.5 vs 1.3, p = 0.019) among severe OSA (REI) ≥30/h) patients. The CPAP treatment associated with an impaired risk of decreased usual activities (OR 0.190, 95% CI 0.042‐0.857, p = 0.031). Though severe OSA was not an independent risk factor for functional ability, whereas higher BMI was an independent risk factor for impaired QOL (p = 0.006, 95%CI 1.047‐1.315).
Conclusions:
Seven years post-stroke the QOL was in good level, although it tended to be lower in stroke patients with severe OSA. The CPAP treatment associated with better usual activities in patients with severe OSA
Computational studies on heavy element systems: fundamentals, bonding properties and emerging insights
No full textAbstract
The frontier of inorganic chemistry increasingly explores the unusual bonding and reactivity that arise when heavy elements adopt low oxidation states. Across the p-block, d-block, and f-block, the interplay of spin–orbit coupling, valence-shell energetics, and ligand interactions unlocks new electronic configurations, covalency, and magnetic properties. Bridging these diverse regimes, this thesis presents three different computational studies that reveal principles for designing and understanding low coordinate, low-valent complexes of heavy elements.
First, energy decomposition and orbital analyses of lutetium(III) metallocenes challenge the traditional view of strictly ionic lanthanide–ligand bonds. Quantitative partitioning of metal–ligand interactions uncovers significant donation into 5d, 6s, and 6p shells, imparting directional covalent character that tunes crystal-field splitting and magnetic anisotropy. Next, a systematic survey of actinide cyclopentadienyl complexes spanning Ac–Lr in oxidation states 0–3 reveals two valence regimes: early actinides access mixed 5f /6d or 5f /7s configurations, whereas mid-series elements stabilize purely 5f -dominated ground states, with a conceptual “break” between Np and Pu marking the transition and correlating valence-shell stability trends with calculated redox potentials. Finally, an ab initio crystalfield framework for main-group single-molecule magnets identifies how isolating a heavy p-element in a minimal σ-donor environment preserves npx/npy orbital degeneracies and yields pronounced axial anisotropy. By modeling np3 electronic configurations in oneand two-coordinate geometries, this work establishes the orbital-symmetry constraints required for bistable spin states and guides the selection of sterically protective ligands that minimize unwanted crystal-field distortions.
Together, these studies establish a coherent picture of how heavy-element valence orbitals respond to low oxidation state, strong spin–orbit coupling, and ligand-field symmetry. The insights into orbital selection rules, covalent mixing, and valence-shell evolution provide predictive guidance for synthesizing new low-valent complexes with bespoke magnetic, redox, or catalytic functions, extending the toolbox of heavy-element chemistry beyond conventional oxidation states. Original papers Chekkottu Parambil, A., & Mansikkamäki, A. (2024). Nature of the metal–ligand bonding in bis (Cyclopentadienyl) and bis (Cyclobutadienyl) lutetium (III) metallocenes. Journal of Organometallic Chemistry, 1007, 123024. https://doi.org/10.1016/j.jorganchem.2024.123024 https://doi.org/10.1016/j.jorganchem.2024.123024 Self-archived version Chekkottu Parambil, A., & Mansikkamäki, A. (2025). Electronic configurations of low-valent actinide bis (cyclopentadienyl) metallocenes. (Manuscript submitted for publication). Mansikkamäki, A., & Chekkottu Parambil, A. (2025). A framework for designing main-group single-molecule magnets. Physical Chemistry Chemical Physics, 27(11), 5739–5758. https://doi.org/10.1039/D4CP04790G https://doi.org/10.1039/D4CP04790G Self-archived version Osajulkaisut Chekkottu Parambil, A., & Mansikkamäki, A. (2024). Nature of the metal–ligand bonding in bis (Cyclopentadienyl) and bis (Cyclobutadienyl) lutetium (III) metallocenes. Journal of Organometallic Chemistry, 1007, 123024. https://doi.org/10.1016/j.jorganchem.2024.123024 https://doi.org/10.1016/j.jorganchem.2024.123024 Rinnakkaistallennettu versio Chekkottu Parambil, A., & Mansikkamäki, A. (2025). Electronic configurations of low-valent actinide bis (cyclopentadienyl) metallocenes. (Manuscript submitted for publication). Mansikkamäki, A., & Chekkottu Parambil, A. (2025). A framework for designing main-group single-molecule magnets. Physical Chemistry Chemical Physics, 27(11), 5739–5758. https://doi.org/10.1039/D4CP04790G https://doi.org/10.1039/D4CP04790G Rinnakkaistallennettu versio Academic dissertation to be presented with the assent of the Doctoral Training Committee of Technology and Natural Sciences of the University of Oulu for public discussion in the Auditorium IT116, Linnanmaa, on February 20th, 2026, at 12 o’clock noon.Abstract
The frontier of inorganic chemistry increasingly explores the unusual bonding and reactivity that arise when heavy elements adopt low oxidation states. Across the p-block, d-block, and f-block, the interplay of spin–orbit coupling, valence-shell energetics, and ligand interactions unlocks new electronic configurations, covalency, and magnetic properties. Bridging these diverse regimes, this thesis presents three different computational studies that reveal principles for designing and understanding low coordinate, low-valent complexes of heavy elements.
First, energy decomposition and orbital analyses of lutetium(III) metallocenes challenge the traditional view of strictly ionic lanthanide–ligand bonds. Quantitative partitioning of metal–ligand interactions uncovers significant donation into 5d, 6s, and 6p shells, imparting directional covalent character that tunes crystal-field splitting and magnetic anisotropy. Next, a systematic survey of actinide cyclopentadienyl complexes spanning Ac–Lr in oxidation states 0–3 reveals two valence regimes: early actinides access mixed 5f /6d or 5f /7s configurations, whereas mid-series elements stabilize purely 5f -dominated ground states, with a conceptual “break” between Np and Pu marking the transition and correlating valence-shell stability trends with calculated redox potentials. Finally, an ab initio crystalfield framework for main-group single-molecule magnets identifies how isolating a heavy p-element in a minimal σ-donor environment preserves npx/npy orbital degeneracies and yields pronounced axial anisotropy. By modeling np3 electronic configurations in oneand two-coordinate geometries, this work establishes the orbital-symmetry constraints required for bistable spin states and guides the selection of sterically protective ligands that minimize unwanted crystal-field distortions.
Together, these studies establish a coherent picture of how heavy-element valence orbitals respond to low oxidation state, strong spin–orbit coupling, and ligand-field symmetry. The insights into orbital selection rules, covalent mixing, and valence-shell evolution provide predictive guidance for synthesizing new low-valent complexes with bespoke magnetic, redox, or catalytic functions, extending the toolbox of heavy-element chemistry beyond conventional oxidation states
Permanent maxillary canine eruption in children with clefts - a retrospective study
No full textAbstract
Objective:
The purpose of this study was to investigate the effect of alveolar bone grafting (ABG) on the eruption timing and the need for deliberation of the permanent maxillary canine in cleft lip and/or palate patients.
Materials and methods:
The study group included 45 cleft sites from a total of 39 unilateral cleft lip and alveolus (CLA, n = 5) and unilateral (n = 22) cleft lip and palate (CLP) and bilateral (n = 12) CLP patients who had undergone treatment in the Oulu Cleft Center (OCC). A split-mouth approach and linear mixed-effects regression analysis was used to compare findings between single individual grafted and non-grafted alveolar sites.
Results:
The maxillary canine angulation had a significant role in the timing of the canine eruption (estimate 0.06, 95% CI 0.04 to 0.08). While ABG seemed to delay the canine eruption, this result was not statistically significant. The eruption of the maxillary canine tooth on the bone grafted side was delayed compared to the eruption of the maxillary canine on the non-grafted side (estimate -0.55, 95% CI -0.99 to -0.11). Another factor affecting the canine eruption was surgical exposure of the canine, and it typically emerged about a year after it had been surgically exposed and deliberated (estimate 1.05, 95% CI 0.40 to 1.70).
Conclusion:
The permanent maxillary canine eruption was slightly delayed after the ABG. Also, the maxillary canine was found to typically emerge about a year after it has been deliberated. The early bone graft had no benefit in terms of the timing of canine eruption. The angulation of the maxillary canine should be taken into consideration when planning ABG to facilitate its eruption. Careful planning and timing of the ABG and multidisciplinary approach have an important role in cleft patients’ treatment.Abstract
Objective:
The purpose of this study was to investigate the effect of alveolar bone grafting (ABG) on the eruption timing and the need for deliberation of the permanent maxillary canine in cleft lip and/or palate patients.
Materials and methods:
The study group included 45 cleft sites from a total of 39 unilateral cleft lip and alveolus (CLA, n = 5) and unilateral (n = 22) cleft lip and palate (CLP) and bilateral (n = 12) CLP patients who had undergone treatment in the Oulu Cleft Center (OCC). A split-mouth approach and linear mixed-effects regression analysis was used to compare findings between single individual grafted and non-grafted alveolar sites.
Results:
The maxillary canine angulation had a significant role in the timing of the canine eruption (estimate 0.06, 95% CI 0.04 to 0.08). While ABG seemed to delay the canine eruption, this result was not statistically significant. The eruption of the maxillary canine tooth on the bone grafted side was delayed compared to the eruption of the maxillary canine on the non-grafted side (estimate -0.55, 95% CI -0.99 to -0.11). Another factor affecting the canine eruption was surgical exposure of the canine, and it typically emerged about a year after it had been surgically exposed and deliberated (estimate 1.05, 95% CI 0.40 to 1.70).
Conclusion:
The permanent maxillary canine eruption was slightly delayed after the ABG. Also, the maxillary canine was found to typically emerge about a year after it has been deliberated. The early bone graft had no benefit in terms of the timing of canine eruption. The angulation of the maxillary canine should be taken into consideration when planning ABG to facilitate its eruption. Careful planning and timing of the ABG and multidisciplinary approach have an important role in cleft patients’ treatment
A longitudinal study exploring paternal stress and well-being, maternal depressive symptoms, and the offspring’s later psychosocial functioning in adolescence and young adulthood
No full textAbstract
Background:
The influence of the father’s well-being on child development has been increasingly studied, but longitudinal studies remain few. This study explores how paternal stress and well-being in the offspring’s middle childhood is associated with the child’s internalizing and externalizing problems and competence in adolescence and young adulthood. In addition, it explores the combined effect of paternal stress and maternal depressive symptoms (MDS) trajectories, on child outcomes.
Method:
The longitudinal study started in 1989 in Tampere, Finland, and included 351 normal population primiparous mothers. MDS were screened prenatally, postnatally at 2 and 6 months, and when the index child was 4–5, 8–9, 16–17, and 27 years old. Fathers participated at the 8–9 years follow-up. The children completed questionnaires when they were 16–17 and 27 years old. Complete data were available from 106 adolescents and 81 young adults.
Results:
The father’s long term health problems were associated with the child’s poorer competence in adolescence. The simultaneous high maternal depressive symptoms trajectory increased the risk. In young adulthood, the father’s poorer health and life satisfaction were associated with the offspring having a lower level of internalizing problems and better adaptive functioning. The MDS trajectory was not associated with the young adult’s outcomes.
Limitations:
The sample size was moderate, and high-symptomatic cases were more common among drop-outs.
Conclusions:
Exposure to paternal stress and poor well-being in middle childhood should be considered as an important risk factor for child development. On the other hand, (mild) childhood adversity may enhance psychosocial functioning in young adulthood.Abstract
Background:
The influence of the father’s well-being on child development has been increasingly studied, but longitudinal studies remain few. This study explores how paternal stress and well-being in the offspring’s middle childhood is associated with the child’s internalizing and externalizing problems and competence in adolescence and young adulthood. In addition, it explores the combined effect of paternal stress and maternal depressive symptoms (MDS) trajectories, on child outcomes.
Method:
The longitudinal study started in 1989 in Tampere, Finland, and included 351 normal population primiparous mothers. MDS were screened prenatally, postnatally at 2 and 6 months, and when the index child was 4–5, 8–9, 16–17, and 27 years old. Fathers participated at the 8–9 years follow-up. The children completed questionnaires when they were 16–17 and 27 years old. Complete data were available from 106 adolescents and 81 young adults.
Results:
The father’s long term health problems were associated with the child’s poorer competence in adolescence. The simultaneous high maternal depressive symptoms trajectory increased the risk. In young adulthood, the father’s poorer health and life satisfaction were associated with the offspring having a lower level of internalizing problems and better adaptive functioning. The MDS trajectory was not associated with the young adult’s outcomes.
Limitations:
The sample size was moderate, and high-symptomatic cases were more common among drop-outs.
Conclusions:
Exposure to paternal stress and poor well-being in middle childhood should be considered as an important risk factor for child development. On the other hand, (mild) childhood adversity may enhance psychosocial functioning in young adulthood
Low-complexity multi-antenna RF wireless power transfer : signal processing and system design
No full textAbstract
The rapid growth of wireless devices and the Internet of Things (IoT) has increased the demand for scalable solutions for delivering energy without physical connections. Radio frequency (RF) wireless power transfer (WPT) enables simultaneous energy delivery to multiple devices over a shared wireless channel, but its efficiency is limited by propagation losses, hardware constraints, and the need to fairly distribute power among receivers under heterogeneous conditions. This thesis addresses these challenges through a systematic study of RF-WPT system design and optimization, covering distributed deployments, metasurface-based architectures, and adaptive charging protocols.
The thesis first investigates hotspot-centric deployments, where energy demand is spatially concentrated. Radio stripes are introduced as distributed transmitters, and their placement and beamforming are optimized to maximize the minimum received power. A clustering-based deployment framework is developed, along with multiple radio stripe configurations ranging from low-complexity structured layouts to free-form cable geometries. The results demonstrate significant performance gains over conventional co-located antenna systems and improved adaptability to varying operating conditions.
To reduce transmitter power consumption, dynamic metasurface antennas (DMA) are integrated into RF-WPT systems. Their tunable architecture enables efficient energy focusing with a limited number of active components. Beamforming and waveform design methods are developed for both linear and non-linear energy harvesting models, showing that DMA-based transmitters can outperform fully digital arrays depending on system configuration and propagation environment.
The thesis then considers beyond-diagonal reconfigurable intelligent surfaces (RIS), which provide enhanced control over the wireless channel. Joint waveform and beamforming optimization algorithms are proposed, revealing that beyond-diagonal RIS can substantially increase harvested energy in rich scattering environments, while highlighting trade-offs relative to diagonal RIS.
Finally, adaptive charging protocols are studied for dynamic and uncertain environments. Reinforcement learning is employed to design power-efficient scheduling strategies under time-varying energy demands. In addition, a sense-then-charge protocol is proposed for scenarios without channel state information, where device locations are estimated through sensing and used for targeted beamforming. Both approaches outperform conventional baseline methods.
Overall, the thesis develops robust, fair, and energy-efficient RF-WPT techniques that support large-scale IoT deployments.Tiivistelmä
Langattomien laitteiden ja esineiden internetin (IoT) nopea kasvu on lisännyt tarvetta skaalautuville ratkaisuille energian siirtämiseksi ilman fyysisiä yhteyksiä. Radiotaajuinen (RF) langaton tehonsiirto (WPT) mahdollistaa energian samanaikaisen toimittamisen useille laitteille yhteisen langattoman kanavan kautta, mutta sen tehokkuutta rajoittavat etenemishäviöt, laitteistorajoitteet sekä energian oikeudenmukainen jakaminen vastaanottajien kesken vaihtelevissa olosuhteissa. Tässä väitöskirjassa näihin haasteisiin vastataan systemaattisella RF-WPT-järjestelmien suunnittelun ja optimoinnin tutkimuksella, joka kattaa hajautetut käyttöönotot, metapintapohjaiset arkkitehtuurit ja mukautuvat latausprotokollat.
Tutkielmassa tarkastellaan ensin hotspot-keskeisiä käyttöönottoja, joissa energiantarve on alueellisesti keskittynyt. Radiojuovat esitellään hajautettuina lähettiminä, joiden sijoittelu ja keilanmuodostus optimoidaan minimivastaanottotehon maksimoimiseksi. Klusterointiin perustuva käyttöönoton viitekehys sekä useita radiojuovien konfiguraatioita kehitetään aina matalan monimutkaisuuden rakenteellisista ratkaisuista vapaamuotoisiin kaapeligeometrioihin. Tulokset osoittavat merkittäviä parannuksia verrattuna perinteisiin keskitettyihin antennijärjestelmiin sekä paremman sopeutumiskyvyn vaihteleviin käyttöolosuhteisiin.
Lähettimen tehonkulutuksen vähentämiseksi RF-WPT-järjestelmiin integroidaan dynaamisia metapinta-antenneja (DMA). Niiden säädettävä rakenne mahdollistaa energian tehokkaan kohdentamisen rajallisella määrällä aktiivisia komponentteja. Keilanmuodostuksen ja aaltomuodon suunnittelumenetelmät kehitetään sekä lineaarisille että epälineaarisille energiankeräysmalleille, ja tulokset osoittavat, että DMA-pohjaiset lähettimet voivat ylittää täysin digitaalisten antenniryhmien suorituskyvyn järjestelmä- ja ympäristötekijöistä riippuen.
Tämän jälkeen tutkielmassa käsitellään ei-diagonaalisia uudelleenkonfiguroitavia älypintoja (RIS), jotka tarjoavat laajemman hallinnan langattomasta kanavasta. Yhteisiä aaltomuodon ja keilanmuodostuksen optimointialgoritmeja esitetään, ja analyysi osoittaa, että ei-diagonaaliset RIS voivat merkittävästi lisätä kerättyä energiaa moniheijasteisissa ympäristöissä samalla, kun kompromissit diagonaalisiin RIS-ratkaisuihin nähden tuodaan esiin.
Lopuksi tutkielmassa tarkastellaan mukautuvia latausprotokollia dynaamisissa ja epävarmoissa ympäristöissä. Vahvistusoppimista hyödynnetään energiatehokkaiden aikataulutusstrategioiden suunnittelussa ajassa vaihtelevien energiantarpeiden alaisuudessa. Lisäksi esitetään sense-then-charge-protokolla tilanteisiin, joissa kanavan tilatietoa ei ole saatavilla ja laitteet eivät vastaa. Tällöin laitteiden sijainnit arvioidaan havainnoinnin avulla ja niitä hyödynnetään kohdennetussa keilanmuodostuksessa. Molemmat lähestymistavat ylittävät perinteiset vertailumenetelmät.
Kokonaisuudessaan väitöskirja kehittää vankkoja, oikeudenmukaisia ja energiatehokkaita RF-WPT-ratkaisuja, jotka tukevat laajamittaisia IoT-järjestelmiä.Academic dissertation to be presented with the assent of the Doctoral Programme Committee of Information Technology and Electrical Engineering of the University of Oulu for public defence in the Wetteri auditorium (IT115), Linnanmaa, on 2 March 2026, at 12 noonAbstract
The rapid growth of wireless devices and the Internet of Things (IoT) has increased the demand for scalable solutions for delivering energy without physical connections. Radio frequency (RF) wireless power transfer (WPT) enables simultaneous energy delivery to multiple devices over a shared wireless channel, but its efficiency is limited by propagation losses, hardware constraints, and the need to fairly distribute power among receivers under heterogeneous conditions. This thesis addresses these challenges through a systematic study of RF-WPT system design and optimization, covering distributed deployments, metasurface-based architectures, and adaptive charging protocols.
The thesis first investigates hotspot-centric deployments, where energy demand is spatially concentrated. Radio stripes are introduced as distributed transmitters, and their placement and beamforming are optimized to maximize the minimum received power. A clustering-based deployment framework is developed, along with multiple radio stripe configurations ranging from low-complexity structured layouts to free-form cable geometries. The results demonstrate significant performance gains over conventional co-located antenna systems and improved adaptability to varying operating conditions.
To reduce transmitter power consumption, dynamic metasurface antennas (DMA) are integrated into RF-WPT systems. Their tunable architecture enables efficient energy focusing with a limited number of active components. Beamforming and waveform design methods are developed for both linear and non-linear energy harvesting models, showing that DMA-based transmitters can outperform fully digital arrays depending on system configuration and propagation environment.
The thesis then considers beyond-diagonal reconfigurable intelligent surfaces (RIS), which provide enhanced control over the wireless channel. Joint waveform and beamforming optimization algorithms are proposed, revealing that beyond-diagonal RIS can substantially increase harvested energy in rich scattering environments, while highlighting trade-offs relative to diagonal RIS.
Finally, adaptive charging protocols are studied for dynamic and uncertain environments. Reinforcement learning is employed to design power-efficient scheduling strategies under time-varying energy demands. In addition, a sense-then-charge protocol is proposed for scenarios without channel state information, where device locations are estimated through sensing and used for targeted beamforming. Both approaches outperform conventional baseline methods.
Overall, the thesis develops robust, fair, and energy-efficient RF-WPT techniques that support large-scale IoT deployments.Tiivistelmä
Langattomien laitteiden ja esineiden internetin (IoT) nopea kasvu on lisännyt tarvetta skaalautuville ratkaisuille energian siirtämiseksi ilman fyysisiä yhteyksiä. Radiotaajuinen (RF) langaton tehonsiirto (WPT) mahdollistaa energian samanaikaisen toimittamisen useille laitteille yhteisen langattoman kanavan kautta, mutta sen tehokkuutta rajoittavat etenemishäviöt, laitteistorajoitteet sekä energian oikeudenmukainen jakaminen vastaanottajien kesken vaihtelevissa olosuhteissa. Tässä väitöskirjassa näihin haasteisiin vastataan systemaattisella RF-WPT-järjestelmien suunnittelun ja optimoinnin tutkimuksella, joka kattaa hajautetut käyttöönotot, metapintapohjaiset arkkitehtuurit ja mukautuvat latausprotokollat.
Tutkielmassa tarkastellaan ensin hotspot-keskeisiä käyttöönottoja, joissa energiantarve on alueellisesti keskittynyt. Radiojuovat esitellään hajautettuina lähettiminä, joiden sijoittelu ja keilanmuodostus optimoidaan minimivastaanottotehon maksimoimiseksi. Klusterointiin perustuva käyttöönoton viitekehys sekä useita radiojuovien konfiguraatioita kehitetään aina matalan monimutkaisuuden rakenteellisista ratkaisuista vapaamuotoisiin kaapeligeometrioihin. Tulokset osoittavat merkittäviä parannuksia verrattuna perinteisiin keskitettyihin antennijärjestelmiin sekä paremman sopeutumiskyvyn vaihteleviin käyttöolosuhteisiin.
Lähettimen tehonkulutuksen vähentämiseksi RF-WPT-järjestelmiin integroidaan dynaamisia metapinta-antenneja (DMA). Niiden säädettävä rakenne mahdollistaa energian tehokkaan kohdentamisen rajallisella määrällä aktiivisia komponentteja. Keilanmuodostuksen ja aaltomuodon suunnittelumenetelmät kehitetään sekä lineaarisille että epälineaarisille energiankeräysmalleille, ja tulokset osoittavat, että DMA-pohjaiset lähettimet voivat ylittää täysin digitaalisten antenniryhmien suorituskyvyn järjestelmä- ja ympäristötekijöistä riippuen.
Tämän jälkeen tutkielmassa käsitellään ei-diagonaalisia uudelleenkonfiguroitavia älypintoja (RIS), jotka tarjoavat laajemman hallinnan langattomasta kanavasta. Yhteisiä aaltomuodon ja keilanmuodostuksen optimointialgoritmeja esitetään, ja analyysi osoittaa, että ei-diagonaaliset RIS voivat merkittävästi lisätä kerättyä energiaa moniheijasteisissa ympäristöissä samalla, kun kompromissit diagonaalisiin RIS-ratkaisuihin nähden tuodaan esiin.
Lopuksi tutkielmassa tarkastellaan mukautuvia latausprotokollia dynaamisissa ja epävarmoissa ympäristöissä. Vahvistusoppimista hyödynnetään energiatehokkaiden aikataulutusstrategioiden suunnittelussa ajassa vaihtelevien energiantarpeiden alaisuudessa. Lisäksi esitetään sense-then-charge-protokolla tilanteisiin, joissa kanavan tilatietoa ei ole saatavilla ja laitteet eivät vastaa. Tällöin laitteiden sijainnit arvioidaan havainnoinnin avulla ja niitä hyödynnetään kohdennetussa keilanmuodostuksessa. Molemmat lähestymistavat ylittävät perinteiset vertailumenetelmät.
Kokonaisuudessaan väitöskirja kehittää vankkoja, oikeudenmukaisia ja energiatehokkaita RF-WPT-ratkaisuja, jotka tukevat laajamittaisia IoT-järjestelmiä
L-PBF technology and mechanical properties of manufactured parts
No full textKandidaatintyön tavoitteena on kertoa aiheeseen perehtymättömälle lukijalle, miten L-PBF-teknologialla metallien 3D-tulostus toimii, mikä tulostimen osien tehtävä on ja millaisia mekaanisia ominaisuuksia tuotteilla on verrattaessa perinteisellä menetelmällä valmistettuihin tuotteisiin.
Työn teoriaosio on ryhmitelty helposti ymmärrettävässä järjestyksessä, jossa ensin kerrotaan koneen toiminnasta, sen jälkeen koneen osista ja lopuksi tarkastellaan tulostettujen kappaleiden mekaanisista ominaisuuksista sekä niihin vaikuttavia tekijöitä.
Työn tuloksena lukija saa tarkan kuvan L-PBF-teknologian toiminnasta ja sillä tulostettujen kappaleiden mekaanisista ominaisuuksista. Tekstin luettuaan lukija osaa kertoa tulostimen osien funktiot ja kuinka kestäviä osista saadaan
Hierarchical Porosity Engineering of Birch‐Derived Carbons via KOH Activation for High‐Performance Aluminum Batteries
No full textAbstract
Aluminum batteries (ABs) present a cost-effective, high-energy alternative to lithium-ion systems, owing to aluminum's abundance and high theoretical capacity. Here, it reports the synthesis of birch wood derived carbons (CBWs) via carbonization of sawdust followed by KOH activation and their evaluation as AB cathodes. Two samples CBW14 and CBW16 are prepared using biochar-to-KOH weight ratios of 1:4 and 1:6, respectively. Both materials are highly disordered, predominantly amorphous carbons, exhibiting Brunauer–Emmett–Teller-specific surface areas of 3015 m2 g−1 (CBW14) and 3306 m2 g−1 (CBW16). When cycled between 0.01 and 2.2 V at 0.1 A g−1, CBW14 and CBW16 delivered discharge capacities of 120 and 140 mAh g−1, respectively. Notably, CBW16 sustained 35 mAh g−1 at a high rate of 10 A g−1 and achieved energy densities of 155 Wh kg−1 at 0.1 A g−1 and 95 Wh kg−1 at 1.0 A g−1. These findings underscore the critical influence of KOH activation parameters on pore architecture and electrochemical performance, pointing the way toward scalable fabrication of efficient carbon cathodes for next-generation aluminum batteries.Abstract
Aluminum batteries (ABs) present a cost-effective, high-energy alternative to lithium-ion systems, owing to aluminum's abundance and high theoretical capacity. Here, it reports the synthesis of birch wood derived carbons (CBWs) via carbonization of sawdust followed by KOH activation and their evaluation as AB cathodes. Two samples CBW14 and CBW16 are prepared using biochar-to-KOH weight ratios of 1:4 and 1:6, respectively. Both materials are highly disordered, predominantly amorphous carbons, exhibiting Brunauer–Emmett–Teller-specific surface areas of 3015 m2 g−1 (CBW14) and 3306 m2 g−1 (CBW16). When cycled between 0.01 and 2.2 V at 0.1 A g−1, CBW14 and CBW16 delivered discharge capacities of 120 and 140 mAh g−1, respectively. Notably, CBW16 sustained 35 mAh g−1 at a high rate of 10 A g−1 and achieved energy densities of 155 Wh kg−1 at 0.1 A g−1 and 95 Wh kg−1 at 1.0 A g−1. These findings underscore the critical influence of KOH activation parameters on pore architecture and electrochemical performance, pointing the way toward scalable fabrication of efficient carbon cathodes for next-generation aluminum batteries
Statistical Characteristics of Electron Precipitation During HSS‐ and ICME‐Driven Storms Observed by the EISCAT Radar
No full textAbstract
The 1–100 keV electron precipitation during storm time has been studied by applying the updated ELSPEC inversion method to field-aligned electron density profiles measured by the EISCAT Tromsø radar at L = 6.5. The statistical properties of peak energy, total energy flux, and total number flux as a function of MLT have been studied for the two main solar wind drivers (high-speed streams, HSSs, and interplanetary coronal mass ejections, ICMEs), and two storm phases (main and recovery) between 1998 and 2023. We found that the peak energy grows after midnight until noon, but the number fluxes behave in the opposite manner, decreasing toward noon. Electron precipitation in this region is believed to be caused by lower-band chorus waves. The peak energies were lower for ICME-driven storms than HSS-driven storms. At 10–12 MLT, the maximum in the mean peak energy was 43 keV for HSS-driven storms and 28 keV for ICME-driven storms. The probable reason is the change in the equatorial magnetic field value during storms affecting resonant energies of electrons. ICME-driven storms were stronger in magnitude than HSS-driven storms, and hence the equatorial magnetic field at L = 6.5 decreased more for ICME-driven storms. The same mechanism can explain why the peak energies in the pre-noon sector during the main phase were lower than during the recovery phase. The number fluxes and energy fluxes were larger in the main phase than in the recovery phase in the morning sector.Abstract
The 1–100 keV electron precipitation during storm time has been studied by applying the updated ELSPEC inversion method to field-aligned electron density profiles measured by the EISCAT Tromsø radar at L = 6.5. The statistical properties of peak energy, total energy flux, and total number flux as a function of MLT have been studied for the two main solar wind drivers (high-speed streams, HSSs, and interplanetary coronal mass ejections, ICMEs), and two storm phases (main and recovery) between 1998 and 2023. We found that the peak energy grows after midnight until noon, but the number fluxes behave in the opposite manner, decreasing toward noon. Electron precipitation in this region is believed to be caused by lower-band chorus waves. The peak energies were lower for ICME-driven storms than HSS-driven storms. At 10–12 MLT, the maximum in the mean peak energy was 43 keV for HSS-driven storms and 28 keV for ICME-driven storms. The probable reason is the change in the equatorial magnetic field value during storms affecting resonant energies of electrons. ICME-driven storms were stronger in magnitude than HSS-driven storms, and hence the equatorial magnetic field at L = 6.5 decreased more for ICME-driven storms. The same mechanism can explain why the peak energies in the pre-noon sector during the main phase were lower than during the recovery phase. The number fluxes and energy fluxes were larger in the main phase than in the recovery phase in the morning sector
Early-career special education teachers´ experiences of their own professional competencies and work adjustment in teaching students with intellectual disabilities
No full textTämän pro gradu -tutkielman tavoitteena oli selvittää, millaisia kokemuksia uran alkuvaiheessa olevilla erityisluokanopettajilla on omista valmiuksistaan ja työhön sopeutumisesta kehitysvammaisten oppilaiden opetuksessa. Kehitysvammaisten oppilaiden opettajana toimiminen edellyttää monipuolisia ammatillisia valmiuksia, sillä työ voi olla vaativaa ja oppilaiden tuen tarpeet moninaisia. Aiemman tutkimustiedon perusteella kehitysvammaisten oppilaiden opetusta koskeva tieto on pedagogiikan kentällä melko vähäistä, joka näkyy myös erityisluokanopettajaopinnoissa. Opettajien uran alkuvaihe koetaan usein haastavana, jonka vuoksi on olennaista tarkastella sitä omien koettujen valmiuksien ja työhön sopeutumisen kautta myös tässä erityispedagogiikan kontekstissa. Tässä tutkielmassa uran alkuvaiheessa olevia erityisluokanopettajia ovat ne, joiden valmistumisesta on kulunut enintään viisi vuotta.
Tutkielma toteutettiin laadullisena tutkimuksena käyttäen fenomenologista lähestymistapaa. Tutkielman aineisto kerättiin sähköisen kyselylomakkeen avulla, johon vastasi 18 erityisluokanopettajaa. Aineisto analysoitiin aineistolähtöisellä sisällönanalyysilla, jonka jälkeen tulokset esiteltiin tutkimuskysymysten mukaan koettujen ammatillisten valmiuksien ja työhön sopeutumisen kokemusten kautta.
Tutkielman tulokset osoittavat, että uran alkuvaiheessa olevat erityisluokanopettajat kokevat omat valmiutensa puutteellisiksi toimia kehitysvammaisten oppilaiden opetuksessa. Ammatillisten valmiuksien kehittyminen näyttäytyy epätasaisena, sillä opettajien taustatekijät vaihtelevat esimerkiksi aiempien työkokemusten tai henkilökohtaisten ominaisuuksien mukaan. Tuloksissa ilmenee myös, että koetut ammatilliset valmiudet sekä työhön sopeutuminen ovat vahvasti yhteydessä toisiinsa: puutteet valmiuksissa näyttäytyvät työhön sopeutumista haastavina tekijöinä.
Tuloksissa näyttäytyy, että työhön sopeutumisen kannalta merkityksellistä on kollegiaalinen tuki ja työyhteisön ilmapiiri. Laadukas ja kattava perehdytys voi sujuvoittaa työhön sopeutumista, kun taas sen puuttuminen voi lisätä työn kuormittavuutta. Tutkielman tulokset tuovat esiin tarpeen kehittää sekä erityisopettajakoulutusta, että koulujen rakenteita, jotta kehitysvammaisten oppilaiden laadukas opetus voidaan turvata