409 research outputs found
Aistitiedon käsittelyn vaikeuksien yhteys kouluakäymättömyyteen ja koulupudokkuuteen
Tiivistelmä. Aistitiedon käsittelyn vaikeudet vaikuttavat toimintakykyyn laaja-alaisesti. Sen vaikutusta kouluakäymättömyyteen ja koulupudokkuuteen ei toistaiseksi ole tutkittu. Tämän tutkielman päätavoitteena on kuvata näihin ilmiöihin liittyvää teoriatietoa ja aiempaa tutkimusta, samalla selvittäen, voisiko näillä ilmiöillä olla yhteyttä toisiinsa.
Tutkielma on toteutettu kuvailevana kirjallisuuskatsauksena. Haasteita tutkielman luomiseen tuotti aiheesta tehtyjen tutkimusten vähäinen määrä. Sekä aistitiedon käsittelyn vaikeudet, että koulupudokkuus ovat niukasti tutkittuja aiheita, joskin koulupudokkuudesta löytyy tutkimuskirjallisuutta hieman enemmän. Tutkimuksia, joissa on tutkittu aistisäätelyn vaikeuksien yhteyttä koulunkäyntiin liittyviin asioihin, on tehty vain autismikirjon oppilaista koostuvissa otoksissa. Näissä tutkimuksissa aistisäätelyn vaikeuksien on todettu olevan yhteydessä oppimiskykyyn, koulumenestykseen ja kouluhyvinvointiin, joilla tiedetään olevan yhteys kohonneeseen koulupudokkuuden riskiin.
Tilastokeskuksen mukaan Suomessa jää vuosittain oppilaita koulupudokkaaksi peruskoulusta ja toisen asteen koulutuksista. Tilastoissa ei kuitenkaan käy ilmi koulun keskeyttämiseen johtaneita syitä. Tutkimuskirjallisuudessa on viitteitä siitä, että aistitiedon käsittelyn vaikeudet liittyvät tekijöihin, joiden tiedetään ennustavan koulupudokkuutta ja koulupudokkuus on erityisen yleistä neuropsykiatrisissa oirekuvissa, joissa aistitiedon käsittelyn vaikeudet ovat yleisiä. Ne eivät kuitenkaan liity pelkästään neuropsykiatrisiin oirekuviin, vaan niitä voi esiintyä myös ilman muita diagnosoitavissa olevia tiloja, ja ne koskettavat mahdollisesti kymmeniä tuhansia peruskoululaisia. Aistitiedon käsittelyn vaikeuksien ja koulupudokkuuden välisiä yhteyksiä selvittämällä mahdollistetaan tehokkaampien tukitoimien kehittäminen ja edistetään koulupudokkuuden ennaltaehkäisyä
High-latitude artificial aurora using the EISCAT high-gain HF facility
The EISCAT high-frequency (HF) transmitter facility at Ramfjord, Norway, has been used to accelerate F-region electrons sufficiently to excite the oxygen atoms and nitrogen molecules, resulting in optical emissions at 630, 557.7 and 427.8 nm. During O-mode transmissions at 5.423 MHz, using 630 MW effective radiated power, in the hours after sunset on 12 November 2001 several new observations were made, including: (1) The first high-latitude observation of an HF induced optical emission at 427.8 nm and (2) Optical rings being formed at HF on followed by their collapse into a central blob. Both discoveries remain unexplained with current theories
Efficient Certified Resolution Proof Checking
We present a novel propositional proof tracing format that eliminates complex
processing, thus enabling efficient (formal) proof checking. The benefits of
this format are demonstrated by implementing a proof checker in C, which
outperforms a state-of-the-art checker by two orders of magnitude. We then
formalize the theory underlying propositional proof checking in Coq, and
extract a correct-by-construction proof checker for our format from the
formalization. An empirical evaluation using 280 unsatisfiable instances from
the 2015 and 2016 SAT competitions shows that this certified checker usually
performs comparably to a state-of-the-art non-certified proof checker. Using
this format, we formally verify the recent 200 TB proof of the Boolean
Pythagorean Triples conjecture
A study to the Iranian Cryptinae (Hymenoptera: Ichneumonidae)
This paper provides faunistic data for 27 species of Cryptinae in Iran, of which 12 species and three genera, Buathra Cameron, Myrmeleonostenus Uchida and Glyphicnemis Foerster, are newly recorded from Iran. Previously recorded species with related references are also included. Distributional map is given for all species of Cryptinae. This study increases the number of known species of Iranian Cryptinae to 55
A Bibliometric Study on Authorship Trends and Research Themes in Knowledge Management Literature
This is the author accepted manuscript. The final version is available from IFKAD via the link in this record.The aim of the study is to identify the contribution of authors in the domain of Knowledge Management (KM). The underlying data is from two leading KM journals, namely, the Journal of Knowledge Management (JKM) and the Journal of Intellectual
Capital (JIC). We downloaded articles from Thomson Reuters Web of Science (WoS),with JKM and JIC-specific searches resulting in 508 and 73 citing articles respectively. The timeframe of analysis was 2009-2016. This dataset was used to create co-citation network visualisations to provide insights into the clusters of authors and research topics. Measures such as Betweenness centrality and hubs-authorities (HITS) were used to identify significant authors and their key themes of interest. More specifically, network analysis identified six dominant research themes, it revealed a total of 14,422 authors
being cited (depicted as nodes in the visualisation) with a total of 1,023,123 citations (edges). Based on the findings of this study, the paper will explore the specific themes and the intellectual turning points in KM research and its evolution. Our bibliometric analysis has practical significance for researchers since it recognises the dominant research areas, and by extension, it identifies those that are still in their infancy; the latter having the potential of representing an interesting research gap. The limitation of the study is that the underlying data is only from two journals (albeit, from the top two journals in KM), which may lead to partially biased results. In future, the aim is to also leverage the analysis to more KM journals, e.g., the top ten journals within the Serenko & Bontis (2013) most updated list
Incrementally Computing Minimal Unsatisfiable Cores of QBFs via a Clause Group Solver API
We consider the incremental computation of minimal unsatisfiable cores (MUCs)
of QBFs. To this end, we equipped our incremental QBF solver DepQBF with a
novel API to allow for incremental solving based on clause groups. A clause
group is a set of clauses which is incrementally added to or removed from a
previously solved QBF. Our implementation of the novel API is related to
incremental SAT solving based on selector variables and assumptions. However,
the API entirely hides selector variables and assumptions from the user, which
facilitates the integration of DepQBF in other tools. We present implementation
details and, for the first time, report on experiments related to the
computation of MUCs of QBFs using DepQBF's novel clause group API.Comment: (fixed typo), camera-ready version, 6-page tool paper, to appear in
proceedings of SAT 2015, LNCS, Springe
On QBF Proofs and Preprocessing
QBFs (quantified boolean formulas), which are a superset of propositional
formulas, provide a canonical representation for PSPACE problems. To overcome
the inherent complexity of QBF, significant effort has been invested in
developing QBF solvers as well as the underlying proof systems. At the same
time, formula preprocessing is crucial for the application of QBF solvers. This
paper focuses on a missing link in currently-available technology: How to
obtain a certificate (e.g. proof) for a formula that had been preprocessed
before it was given to a solver? The paper targets a suite of commonly-used
preprocessing techniques and shows how to reconstruct certificates for them. On
the negative side, the paper discusses certain limitations of the
currently-used proof systems in the light of preprocessing. The presented
techniques were implemented and evaluated in the state-of-the-art QBF
preprocessor bloqqer.Comment: LPAR 201
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Optical Waveplates Based on Birefringence of Anisotropic Two-Dimensional Layered Materials
Birefringence is an inherent optical property of anisotropic materials introduced by the anisotropic confinement in their crystal structures. It enables manipulation of light propagation properties (e.g., phase velocity, reflection, and refrac- tion) for various photonic and optoelectronic applications, including waveplates and liquid crystal displays. Two-dimensional (2D) layered materials with high anisotropy are currently gaining an increasing interest for polarization-integrated nano- device applications, which advances the research on birefringent materials. In this article, we investigate the optical birefrin- gence of three anisotropic 2D layered materials (black phosphorus (BP), rhenium disulfide (ReS2), and rhenium diselenide (ReSe2)). We demonstrate that the birefringence in BP (~0.245) is ~ 6 times larger than that of ReS2 (~0.037) and ReSe2 (~0.047) at 520 nm and is comparable to the current state of the art bulk materials (e.g., CaCO3). We use these 2D materials to fabricate atomically-thin optical waveplates and investigate their performance. In particular, for BP, we observe a polarization-plane rotation of ~0.05° per atomic layer at 520 nm. Our results show that the relatively large birefringence of anisotropic 2D layered materials can enable accurate manipulation of light polarization with atomically controlled device thickness for various applications where integrated, nanoscale polarization-controllers are required
High-k GaAs metal insulator semiconductor capacitors passivated by ex-situ plasma-enhanced atomic layer deposited AlN for Fermi-level unpinning
This paper examines the utilization of plasma-enhanced atomic layer deposition grown AlN in the fabrication of a high-kinsulator layer on GaAs. It is shown that high-kGaAsMIS capacitors with an unpinned Fermi level can be fabricated utilizing a thin ex-situ deposited AlNpassivation layer. The illumination and temperature induced changes in the inversion side capacitance, and the maximum band bending of 1.2 eV indicates that the MIS capacitor reaches inversion. Removal of surface oxide is not required in contrast to many common ex-situ approaches.Peer reviewe
Optimization of single crystal mirrors for ITER diagnostics
Diagnostic mirrors are planned to be used in all optical diagnostics in ITER. Degradation of mirrors due to e.g. deposition of plasma impurities will hamper the entire performance of affected diagnostics. in situ mirror cleaning by plasma sputtering is presently envisaged for the recovery of contaminated mirrors. There are observations showing a signature of sputtering dependence on crystal orientation. Should such a dependence exist, the sputtering of single crystal mirrors could be minimized, thus prolonging a mirror lifetime. Four single crystal molybdenum mirrors with different orientations were produced to study the effect of crystal orientation on sputtering. Mirrors were exposed to argon plasma under identical plasma conditions relevant to those expected in the mirror cleaning systems of ITER. The energy of impinging ions was about 60 eV. The amount of sputtered material corresponded to about a hundred mirror cleaning cycles in argon. Plasma exposures did not affect the mirror reflectivity. The maximum decrease of specular reflectivity did not exceed 5% at 250 nm. The mirrors with orientations [110]/[101] demonstrated up to 42% less sputtering than the mirrors with other crystal orientations. These findings outline the advantage of a favorable crystal orientation for a cleaning of heavy contaminants from ITER mirrors.Peer reviewe
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