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.
Flokkar í Opnum vísindum
Veldu flokk til að skoða.
- University of Iceland
- University of Akureyri
- Bifröst University
- Hólar University College
- Reykjavík University
- IRIS
- Agricultural University of Iceland
- National and University Library of Iceland
- Iceland University of the Arts
Nýlega bætt við
Staðgreiðsla og skattbyrði í 30 ár
(2019) Hall, Axel; Viðskipta- og hagfræðideild
Í þessari grein er markmiðið að lýsa núverandi skattkerfi tekjuskatts sem hefur verið við lýði frá upptöku staðgreiðslunnar 1988. Hér er kerfið greint, eiginleikum þess lýst og það að einhverju leyti sett í norrænt samhengi. Til að auðvelda umfjöllun eru settar fram formlegar skilgreiningar á skattbyrði og jaðarsköttum. Mælikvarðar á jöfnun skattkerfis eru ennfremur settir fram. Þegar litið er yfir allt tímabil staðgreiðslunnar sést að tengsl persónuafsláttar við vísitölu neysluverðs á tímum hækkunar kaupmáttar hafa aukið meira skattbyrði hjá hinum tekjulægri en þeim sem hafa hærri tekjur, sem á móti voru með hærri skattbyrði fyrir. Þessi þróun er hér nefnd raunskattskrið og langtímaþróun í þessu efni hefur yfirgnæft aðra hluta staðgreiðslukerfisins og greiðendum tekjuskatts hefur fjölgað. Framangreindar breytingar hafa verið umdeildar og fræðimenn m.a. tekist á um þær. Hér er þróuninni lýst án þess að leitast við að leggja dóm á þá pólitísku vegferð sem hefur verið farin eða vangaveltur um aðrar leiðir mögulegar hingað til. Rauði þráðurinn hefur verið þróun skattleysismarka og persónuafsláttar. Kerfi með framangreindri þróun þarf að endurstilla reglulega standi vilji til að viðhalda lóðréttri jöfnun í kerfinu. Það kallar á stefnumótun um þrep (stig og fjölda), mörk þrepa (t.a.m. skattleysismörk) og þróun markanna yfir tíma. Í þessari grein er farið yfir þá valkosti sem stjórnvöld hafa sett fram varðandi breytingar á skattkerfinu og niðurstaða þeirrar stefnumörkunar greind með áhrifum á jöfnun í kerfi tekjuskatts.
Soft tissue radiodensity parameters mediate the relationship between self-reported physical activity and lower extremity function in AGES-Reykjavík participants
(2021-10-11) Edmunds, Kyle J.; Okonkwo, Ozioma C.; Sigurðsson, Sigurður; Lose, Sarah R.; Guðnason, Vilmundur G.; Carraro, Ugo; Gargiulo, Paolo; Department of Engineering
Although previous studies have highlighted the association between physical activity and lower extremity function (LEF) in elderly individuals, the mechanisms underlying this relationship remain debated. Our recent work has recognized the utility of nonlinear trimodal regression analysis (NTRA) parameters in characterizing changes in soft tissue radiodensity as a quantitative construct for sarcopenia in the longitudinal, population-based cohort of the AGES-Reykjavík study. For the present work, we assembled a series of prospective multivariate regression models to interrogate whether NTRA parameters mediate the 5-year longitudinal relationship between physical activity and LEF in AGES-Reykjavík participants. Healthy elderly volunteers from the AGES-Reykjavík cohort underwent mid-thigh X-ray CT scans along with a four-part battery of LEF tasks: normal gait speed, fastest-comfortable gait speed, isometric leg strength, and timed up-and-go. These data were recorded at two study timepoints which were separated by approximately 5 years: AGES-I (n = 3157) and AGES-II (n = 3098). Participants in AGES-I were likewise administered a survey to approximate their weekly frequency of engaging in moderate-to-vigorous physical activity (PAAGES-I). Using a multivariate mediation analysis framework, linear regression models were assembled to test whether NTRA parameters mediated the longitudinal relationship between PAAGES-I and LEFAGES-II; all models were covariate-adjusted for age, sex, BMI, and baseline LEF, and results were corrected for multiple statistical comparisons. Our first series of models confirmed that all four LEF tasks were significantly related to PAAGES-I; next, modelling the relationship between PAAGES-I and NTRAAGES-II identified muscle amplitude (Nm) and location (μm) as potential mediators of LEF to test. Finally, adding these two parameters into our PAAGES-I → LEFAGES-II models attenuated the prior effect of PAAGES-I; bootstrapping confirmed Nm and μm as significant partial mediators of the PAAGES-I → LEFAGES-II relationship, with the strongest effect found in isometric leg strength. This work describes a novel approach toward clarifying the mechanisms that underly the relationship between physical activity and LEF in aging individuals. Identifying Nm and μm as significant partial mediators of this relationship provides strong evidence that physical activity protects aging mobility through the preservation of both lean tissue quantity and quality.
Caffeine exposure from beverages and its association with self-reported sleep duration and quality in a large sample of Icelandic adolescents
(2021-11) Halldórsson, Þórhallur Ingi; Kristjánsson, Álfgeir Logi; Þórisdóttir, Ingibjörg E.; Oddsdóttir, Charlotta; Sveinbjörnsson, Jóhannes; Benediktsson, Rafn; Sigfúsdóttir, Inga Dóra; Jörundsdóttir, Hrönn Ólína; Gunnlaugsdóttir, Helga; Halldorsson, T I
Previous risk assessments have concluded that adolescent's caffeine exposure from energy drinks (ED) are of limited concern. Recent surveys have, however, shown substantial increase in consumption. This cross-sectional survey conducted in 2020 estimated caffeine exposure from beverages among ∼80% of all 13-15-year-old adolescents (n = 10358) relative to the European Food Safety Authority's level of no safety concern of (3.0 mg/kg bw) and level for effects on sleep (1.4 mg/kg bw). Associations with self-reported sleep duration and quality were also explored. ED consumers were more likely to exceed the limit of no safety concern (prevelance: 12–14%) compared to non-ED-consumers (1–2%). Exceeding the limit for effects on sleep was also higher among ED consumers (31–38%) than non-ED-consumers (5–8%). Across categories of low (<0.5 mg/kg bw) to high (>3.0 mg/kg bw) caffeine intake, the prevalence of participants sleeping <6 h increased from 3% to 24%, respectively. The corresponding adjusted Prevalence Ratio was 4.5 (95% CI: 3.6, 5.7) and mean decrease in duration of sleep was 0.74 h (95% CI: 0.65, 0.84). In conclusion, caffeine intake from beverages above the limit of no safety concern was largely confined to ED consumers. Consistent with effects from intervention studies in adults, caffeine intake was strongly associated with self-reported sleep duration in this representative population.
Narcissism and social media : The role of communal narcissism
(2021-09-26) Kristinsdóttir, Kolbrún Harpa; Gylfason, Haukur Freyr; Sigurvinsdóttir, Rannveig S.; Department of Business and Economics; Department of Psychology
Agentic narcissism and vulnerable narcissism have been widely studied in relation to social media use. However, with research on communal narcissism in its early stages, the current study examines communal narcissism in relation to social media use. Specifically, the current study investigates whether communal narcissism is related to use and frequency of use of the popular social networking sites Instagram, Reddit and Twitter, and if communal narcissism relates to the importance of receiving feedback and to the quality-rating of self-presented content on those plat-forms. A total of 334 individuals were recruited from Amazon Mechanical Turk, with two-thirds being male (66.7%). A regression analysis showed that communal narcissism was related to in-creased use of Instagram and Twitter but not Reddit. Sharing content, the importance of feedback and better than average ratings had positive associations with communal narcissism. The relationship between communal narcissism and sharing on social media was fully mediated by wanting validation on social media and higher ratings of self-presented content. Communal narcissism had a notably strong relationship with wanting validation on all platforms and our results suggest that communal narcissism might be especially relevant in the context of social media use.
P300 Analysis Using High-Density EEG to Decipher Neural Response to rTMS in Patients With Schizophrenia and Auditory Verbal Hallucinations
(2020-11-20) Aubonnet, Romain; Banea, Ovidiu C.; Sirica, Roberta; Wassermann, Eric M.; Yassine, Sahar; Jacob, Deborah; Magnúsdóttir, Brynja Björk; Haraldsson, Magnús; Stefansson, Sigurjon B.; Jónasson, Viktor D.; Ívarsson, Eysteinn; Jónasson, Aron D.; Hassan, Mahmoud; Gargiulo, Paolo
Schizophrenia is a complex disorder about which much is still unknown. Potential treatments, such as transcranial magnetic stimulation (TMS), have not been exploited, in part because of the variability in behavioral response. This can be overcome with the use of response biomarkers. It has been however shown that repetitive transcranial magnetic stimulation (rTMS) can the relieve positive and negative symptoms of schizophrenia, particularly auditory verbal hallucinations (AVH). This exploratory work aims to establish a quantitative methodological tool, based on high-density electroencephalogram (HD-EEG) data analysis, to assess the effect of rTMS on patients with schizophrenia and AVH. Ten schizophrenia patients with drug-resistant AVH were divided into two groups: the treatment group (TG) received 1 Hz rTMS treatment during 10 daily sessions (900 pulses/session) over the left T3-P3 International 10-20 location. The control group (CG) received rTMS treatment over the Cz (vertex) EEG location. We used the P300 oddball auditory paradigm, known for its reduced amplitude in schizophrenia with AVH, and recorded high-density electroencephalography (HD-EEG, 256 channels), twice for each patient: pre-rTMS and 1 week post-rTMS treatment. The use of HD-EEG enabled the analysis of the data in the time domain, but also in the frequency and source-space connectivity domains. The HD-EEG data were linked with the clinical outcome derived from the auditory hallucinations subscale (AHS) of the Psychotic Symptom Rating Scale (PSYRATS), the Quality of Life Scale (QoLS), and the Depression, Anxiety and Stress Scale (DASS). The general results show a variability between subjects, independent of the group they belong to. The time domain showed a higher N1-P3 amplitude post-rTMS, the frequency domain a higher power spectral density (PSD) in the alpha and beta bands, and the connectivity analysis revealed a higher brain network integration (quantified using the participation coefficient) in the beta band. Despite the small number of subjects and the high variability of the results, this work shows a robust data analysis and an interplay between morphology, spectral, and connectivity data. The identification of a trend post-rTMS for each domain in our results is a first step toward the definition of quantitative neurophysiological parameters to assess rTMS treatment.