Opin vísindi
Opin vísindi er varðveislusafn vísindaefnis og doktorsritgerða í opnum aðgangi á vegum íslenskra háskóla og Landsbókasafns Íslands - Háskólabókasafns.
Opinn aðgangur að rannsóknaniðurstöðum er í samræmi við 10. gr. laga nr. 3/2003 um opinberan stuðning við vísindarannsóknir sem og kröfur innlendra og erlendra rannsóknasjóða. Markmiðið með opnum aðgangi er að niðurstöður rannsókna séu aðgengilegar sem flestum óhindrað og án endurgjalds á rafrænu formi. Vistun í varðveislusafninu er varanleg og ætlað að tryggja aðgang að vísindaefni íslenskra háskóla í opnum aðgangi um ókomna tíð. Varðveislusafnið Opin vísindi er tengt við rannsóknagáttina IRIS og rannsóknaniðurstöður í opnum aðgangi sem eru skráðar í IRIS eru um leið vistaðar og gerðar aðgengilegar til framtíðar í varðveislusafninu. Með því að safna þessu efni saman í eitt safn verður aðgangur að því einfaldur og þægilegur fyrir alla sem vilja kynna sér það og geta þannig notið þess öfluga vísindastarfs sem fram fer í háskólum landsins.
Varðveislusafnið er OpenAIRE / OpenAIREplus samhæft og samrýmist kröfum sem gerðar eru um birtingu rannsóknaniðurstaðna úr verkefnum sem styrkt eru úr evrópsku rannsóknaáætlununum FP7 og H2020.
Varðveislusafnið notar opna hugbúnaðinn DSpace.
Opinn aðgangur að rannsóknaniðurstöðum er í samræmi við 10. gr. laga nr. 3/2003 um opinberan stuðning við vísindarannsóknir sem og kröfur innlendra og erlendra rannsóknasjóða. Markmiðið með opnum aðgangi er að niðurstöður rannsókna séu aðgengilegar sem flestum óhindrað og án endurgjalds á rafrænu formi. Vistun í varðveislusafninu er varanleg og ætlað að tryggja aðgang að vísindaefni íslenskra háskóla í opnum aðgangi um ókomna tíð. Varðveislusafnið Opin vísindi er tengt við rannsóknagáttina IRIS og rannsóknaniðurstöður í opnum aðgangi sem eru skráðar í IRIS eru um leið vistaðar og gerðar aðgengilegar til framtíðar í varðveislusafninu. Með því að safna þessu efni saman í eitt safn verður aðgangur að því einfaldur og þægilegur fyrir alla sem vilja kynna sér það og geta þannig notið þess öfluga vísindastarfs sem fram fer í háskólum landsins.
Varðveislusafnið er OpenAIRE / OpenAIREplus samhæft og samrýmist kröfum sem gerðar eru um birtingu rannsóknaniðurstaðna úr verkefnum sem styrkt eru úr evrópsku rannsóknaáætlununum FP7 og H2020.
Varðveislusafnið notar opna hugbúnaðinn DSpace.
Nýlega bætt við
Gradient Clock Synchronization with Practically Constant Local Skew
(Association for Computing Machinery, 2026-07-01) Lenzen, Christoph; Department of Computer Science
Gradient Clock Synchronization (GCS) is the task of minimizing the local skew, i.e., the clock offset between neighboring clocks, in a larger network. While asymptotically optimal bounds are known, from a practical perspective they have crucial shortcomings:• Local skew bounds are determined by upper bounds on offset estimation that need to be guaranteed throughout the entire lifetime of the system.• Worst-case frequency deviations of local oscillators from their nominal rate are assumed, yet frequencies tend to be much more stable in the (relevant) short term.State-of-the-art deployed synchronization methods adapt to the true offset measurement and frequency errors, but achieve no nontrivial guarantees on the local skew.In this work, we provide a refined model and novel analysis of existing techniques for solving GCS in this model. By requiring only stability of measurement and frequency errors, we can circumvent existing lower bounds, leading to dramatic improvements under very general conditions. For example, if links exhibit a uniform worst-case estimation error of Δ and a change in estimation errors of δ ≪ Δ on relevant time scales, we bound the local skew by O( (Equation Presented ) D) for networks of diameter D, effectively "breaking"the established Ω(Δ log D) lower bound, which holds when δ = Δ. Surprisingly, these results require only very limited knowledge of Δ. In particular, the likely dominant term of O( (Equation Presented ) in the local skew is determined by the actual link performance, not an upper bound covering worst-case conditions.The full version of this paper [17] also shows how to achieve full self-stabilization, perform external synchronization, and limit the influence of local oscillators on δ to scale with the change of frequency of an individual oscillator on relevant time scales.
Finite-Element Analysis of the Quasi-Static Response of Concrete Specimens Containing Polymeric Self-Healing Microcapsules
(2026-06) Zhelyazov, Todor
Healing agent encapsulated in polymeric microcapsules has proven its ability to seal surface and internal cracks. Focused on mitigating the negative impact of capsules on the properties of fresh cement paste and hardened cementitious matrix, uncertainties in self-healing triggering, and poor control of the released quantity, researchers report technological improvements in predominantly experimental studies. However, practical applications will necessitate lightweight models that capture all the characteristics of practical importance. Analysis of the scientific literature reveals the lack of such models adapted for cementitious composites. In this paper, a model rooted in continuum damage mechanics, tuned based on empirical data, is used in the finite element analysis of concrete specimens containing polymer self-healing microcapsules to quantify self-healing efficiency and local damage-healing behavior. The predicted increase in the self-healing rate is more pronounced for specimens subjected to compression compared to that for elements subjected to four-point bending. Thus, for a 20% increase in healing efficiency, strength recovery in compression increases from 18.5% to 32% for C25 and C30, respectively, whereas the corresponding values for tension in the tension-be-flexure setup are 3.5% and 5.3%.
Estimation of the Knee Joint with Single-Camera Smartphone
(2026-04) Russo, Michela; Ricciardi, Carlo; Romano, Maria; Santoriello, Vittorio; Ponsiglione, Alfonso Maria; Amato, Francesco; Spadea, Maria Francesca; Department of Engineering
(1) Background: Gait analysis provides quantitative information on walking patterns and has proven invaluable for assessing motor function in rehabilitation programmes. A markerless motion capture system combining computer vision techniques provides low-cost, real-time, portable gait analysis. (2) Methods: The kinematics of the knee and ankle of twenty-seven healthy volunteers were assessed using a single smartphone camera combined with the MediaPipe human pose estimation framework. The system was validated using the OPAL wearable sensor system by APDM Wearable Technologies. (3) Results: Findings showed close correspondence between the two systems for knee kinematics showing a mean absolute error of 4.10° ± 2.32° and 3.15° ± 3.10° for right and left knee flexion, respectively, and a mean absolute error of 2.30° ± 2.01° and 3.12° ± 2.63° for right and left knee extension, respectively. The mean absolute error for right and left knee range of motion was found to be 4.55° ± 3.12° and 4.15° ± 3.01°, respectively. Moreover, Bland–Altman plots indicated minimal bias (average 0.6 for flexion, average 0.47 for the extension, and 0.30 for the range of motion) and excellent correlation for knee flexion bilaterally (0.916 and 0.845 for the right and left side, respectively), with slightly lower but still satisfactory agreement for knee extension (0.862 and 0.845 for the right and left side, respectively). Conversely, ankle measurements revealed poor concordance: dorsiflexion and range of motion presented significant differences and systematic errors, while plantarflexion showed no statistical difference but weak correlation. (4) Conclusions: This study demonstrated that combining a smartphone camera with a human pose estimation framework allows for low-cost, real-time, portable gait analysis, particularly of the knee joint.
Early-Stabilizing Counting
(Association for Computing Machinery, 2026-07-01) Lenzen, Christoph; Loss, Julian; Department of Computer Science
Synchronous Counting is the task of reaching agreement on a common round counter in a synchronous system of n nodes with up to t Byzantine faults in a self-stabilizing manner. That is, after transient faults may have arbitrarily corrupted the system state and ceased, the at least n - t non-faulty nodes need to (re-)establish that (i) their local outputs are identical and (ii) increase by 1 modulo C in each round. An overhead-free reduction from consensus shows that all known lower bounds and impossibilities for consensus carry over to the counting problem. In the other direction, prior work has established that a consensus algorithm A can be turned into a counting algorithm at small overhead relative to the running time and bit complexity of A, without losing resilience.Taking inspiration from early-stopping consensus protocols, in this work we introduce the concept of early stabilization. That is, if there are 0 ≤ f ≤ t (persistent) faults in an execution, the algorithm should stabilize in a number of rounds that depends on f only. Likewise, we seek to achieve an amortized bit complexity that is adaptive in the number of actual faults f. By developing a number of modular building blocks suitable to these goals, we develop a C-counting algorithm that stabilizes within asymptotically optimal O(f + 1) rounds, has message size O(log2 n + log C), and has amortized bit complexity O(n(f log C + log2 n)).
Disclosing depressive symptoms : perceived sensitivity of PHQ-9 items in a general population sample
(2026-12) Kristófersdóttir, Kristín Hulda; Vésteinsdóttir, Vaka; Kristjánsdóttir, Hafrún; Karlsson, Thorlakur; Thorsdottir, Fanney; Department of Sport Science; Department of Psychology
Background: The Patient Health Questionnaire-9 (PHQ-9) is one of the most widely used tools for screening and assessing depression. However, previous research has yielded inconsistent results regarding its factor structure, with studies suggesting either a one- or two-factor model. One possible explanation is socially desirable responding (SDR), which may arise if some items are perceived as more sensitive than others. This study examines whether such differences in perceived sensitivity exist and how they correspond to patterns reported in prior factor-analytic research. Methods: A total of 273 participants completed 36 paired comparisons of the PHQ-9 items, indicating which symptoms they would find more uncomfortable to disclose. Additionally, absolute judgments were collected, where participants rated each item as either uncomfortable or not uncomfortable to disclose. Data were analyzed using a paired comparisons model rooted in Thurstone’s law of comparative judgment to estimate the relative sensitivity of each item and whether they were more or less likely to be judged as (not) uncomfortable to disclose. Kendall’s coefficients of consistence and agreement were calculated to evaluate the internal consistency of participants’ responses and the level of agreement between them. Results: Results showed that cognitive/affective symptoms, such as feelings of worthlessness and depressed mood were perceived as more sensitive than somatic symptoms like fatigue and sleep disturbances. Notably, the sensitivity estimates obtained in this study align closely with prior factor analytic findings that have supported a two-factor model distinguishing cognitive/affective and somatic symptoms. Conclusions: These findings suggest that social desirability may contribute to the underreporting of certain depression symptoms, potentially helping to explain inconsistencies in the PHQ-9’s factor structure. Researchers and clinicians should consider the impact of SDR when interpreting PHQ-9 scores to enable more accurate assessments of depression symptom severity.
Flokkar í Opnum vísindum
Veldu flokk til að skoða.
- University of Iceland
- University of Akureyri
- Bifröst University
- Hólar University College
- IRIS
- Agricultural University of Iceland
- National and University Library of Iceland
- Iceland University of the Arts