Low-achieving students’ participation to collaborative learning and group-level regulation

Abstract. The aim of this thesis was to first explore low-achieving students’ participation to collaborative group learning interaction. Second, the thesis explored low-achieving students’ participation to group-level regulation of learning. Students who regulate their own learning process, individually and in groups, have been found to achieve higher learning outcomes. In collaborative groups, students engage in interactions to negotiate strategy and construct shared knowledge. To regulate their learning, student groups actively direct their efforts, and exercise agency by controlling their learning, strategic choices, learning goals, and task engagement, rather than relying on instructors to do it for them. As such, students take an active role in their own learning, and in doing so, demonstrate a high level of self-efficacy and motivation towards learning. In this study, 31 students, nine of which low-achieving in a physics individual examination, were selected to explore and compare low-achieving students’ collaborative activity through coding and analysis of video data. Through two research questions, this thesis aimed to explore: 1) how low-achieving students participate in small group collaborative interaction, and 2) how low-achieving students participate in group-level regulation of learning. Results suggest that some students regardless of achievement level appear considerably inactive in group-level regulation. This thesis also found that initiating regulation does not seem to be distributed evenly between group members, but rather that an individual member often has the lead in initiating group-level regulation. It also appears that low-achieving students may be less active in metacognitive interaction and less likely to take a lead role in group interaction and regulatory activities. However, larger samples of low-achieving students are necessary for generalizable results on achievement groups. Future research should look to explore the factors influencing individual low-achieving student activity in collaborative learning and regulation of learning. The main implications to teaching should be to aim to develop effective solutions for identifying and supporting low-achieving students who are consistently inactive in collaborative learning and regulation of learning

Mouse T-cells restrict replication of human immunodeficiency virus at the level of integration

<p>Abstract</p> <p>Background</p> <p>The development of an immunocompetent, genetically modified mouse model to study HIV-1 pathogenesis and to test antiviral strategies has been hampered by the fact that cells from native mice do not or only inefficiently support several steps of the HIV-1 replication cycle. Upon HIV-1 infection, mouse T-cell lines fail to express viral proteins, but the underlying replication barrier has thus far not been unambiguously identified. Here, we performed a kinetic and quantitative assessment of consecutive steps in the early phase of the HIV-1 replication cycle in T-cells from mice and humans.</p> <p>Results</p> <p>Both T-cell lines and primary T-cells from mice harbor a severe post-entry defect that is independent of potential species-specTR transactivation. Reverse transcription occurred efficiently following VSV-G-mediated entry of virions into mouse T-cells, and abundant levels of 2-LTR circles indicated successful nuclear import of the pre-integration complex. To probe the next step in the retroviral replication cycle, i.e. the integration of HIV-1 into the host cell genome, we established and validated a nested real-time PCR to specifically quantify HIV-1 integrants exploiting highly repetitive mouse <it>B1 </it>elements. Importantly, we demonstrate that the frequency of integrant formation is diminished 18- to > 305-fold in mouse T-cell lines compared to a human counterpart, resulting in a largely abortive infection. Moreover, differences in transgene expression from residual vector integrants, the transcription off which is cyclin T1-independent, provided evidence for an additional, peri-integrational deficit in certain mouse T-cell lines.</p> <p>Conclusion</p> <p>In contrast to earlier reports, we find that mouse T-cells efficiently support early replication steps up to and including nuclear import, but restrict HIV-1 at the level of chromosomal integration.</p

Vieras kieli, lukivaikeus ja fonologinen prosessointi

Tiivistelmä. Lukivaikeus eli dysleksia on neurobiologinen kapea-alainen oppimisen vaikeus, joka ilmenee pääasiassa teknisen lukutaidon hitautena ja epätarkkuutena. Lukivaikeuden taustalla katsotaan vaikuttavan heikot fonologisen prosessoinnin taidot. Fonologisen prosessoinnin taitoihin lukeutuvat yleisesti fonologinen tietoisuus, fonologinen työmuisti ja nopea sarjallinen nimeäminen. Lukivaikeus aiheuttaa tavallisesti oppimisen haasteita äidinkielessä, mutta sen yhteyksiä vieraan kielen oppimiseen on tutkittu verrattain vähemmän. Vieras kieli on kieli, jota ei puhuta oppijan elinympäristössä, vaan jonka hän oppii koulussa tai muussa oppimisympäristössä pääosin opetuksen tuloksena. Vieraan kielen oppimisen katsotaan tapahtuvan kielen ortografisten ominaisuuksien ja oppijan yksilöllisten ominaisuuksien yhteisvaikutuksen tuloksena. Kirjain-äännevastaavuudeltaan johdonmukaiset kielet ovat yleisesti ottaen helpompia oppia, kuin kirjain-äännevastaavuudeltaan epäjohdonmukaiset kielet. Oppijan yksilöllisiä ominaisuuksia sen sijaan ovat erilaiset kielelliset perustaidot ja kognitiiviset kyvyt, joita kaikki kieltenoppiminen edellyttää. Tällaisia taitoja ovat myös fonologisen prosessoinnin taidot. Fonologisen prosessoinnin taidoista kaikki kolme olivat jossain määrin yhteydessä lukemiseen ja vieraan kielen oppimiseen. Suomalaisessa kontekstissa vähiten merkittävä tekijä lienee fonologinen tietoisuus, kun taas fonologisen työmuistin yhteydestä vieraan kielen sanaston oppimiseen on saatu monia merkittäviä tuloksia. Nopean nimeämisen sen sijaan todettiin olevan lähinnä toimiva ennustaja äidinkielen lukutaidossa. Varhaistuvan kieltenopetuksen myötä on tärkeää kiinnittää entistä tarkempaa huomiota lukivaikeuksisten oppilaiden tuentarpeeseen paitsi äidinkielessä myös vieraissa kielissä, joiden opiskelussa äidinkielen oppimisen pulmat voivat entisestään korostua

An analysis of the acoustic cavitation noise spectrum: The role of periodic shock waves

Research on applications of acoustic cavitation is often reported in terms of the features within the spectrum of the emissions gathered during cavitation occurrence. There is, however, limited understanding as to the contribution of specific bubble activity to spectral features, beyond a binary interpretation of stable versus inertial cavitation. In this work, laser-nucleation is used to initiate cavitation within a few millimeters of the tip of a needle hydrophone, calibrated for magnitude and phase from 125 kHz to 20 MHz. The bubble activity, acoustically driven at f0 = 692 kHz, is resolved with high-speed shadowgraphic imaging at 5 × 106 frames per second. A synthetic spectrum is constructed from component signals based on the hydrophone data, deconvolved within the calibration bandwidth, in the time domain. Cross correlation coefficients between the experimental and synthetic spectra of 0.97 for the f 0/2 and f 0/3 regimes indicate that periodic shock waves and scattered driving field predominantly account for all spectral features, including the sub-harmonics and their over-harmonics, and harmonics of f 0

І. Дамейка: мінеролаг і картограф

Материалы V Междунар. науч. конф. студентов, аспирантов и молодых ученых, Гомель, 24 мая 2012 г

The most difficult at-fault fatal crashes to avoid with current active safety technology

Objective We studied which current fatal at-fault crashes would occur despite the most advanced current active safety devices (up to SAE level 2 of driving automation) and how frequent these crashes would be. Methods We carried out a cross-sectional study of passenger cars that were first registered during the period 1st January 2010 to 31st December 2017 in Finland. To gain the true exposure for these cars, we accessed the national Vehicular and Driver Data Register to obtain the mileage information and the registration count for the study period of 2010-17. Similarly, we accessed the registry of Finnish road accident investigation teams and included all fatal at-fault crashes among the cars in our study for the same period. We used a real world reference technology for each active safety system in our analysis and chose one car brand as an example. This gave us exact system specifications and enabled testing the operation of the systems on the road. We performed field tests to gain further information on the precise operation of the safety systems in different operating conditions. Finally, we gathered all information on the studied active safety systems and analyzed the investigated at-fault fatal crashes case-by-case using our four level method. Results Cars in our study were the primary party in 113 investigated fatal accidents during the years 2010-17. In 87 of the accidents, the leading cause of death was the injuries due to the crash, and these cases were classified as “unavoidable” (n = 58, 67 %), “avoidable” (n = 26, 30 %) or unsolved (n = 3, 3 %). Of the 58 “unavoidable” crashes 21 (36 %) were suicides, 21 (36%) involved active driver input which would have prevented the safety system operation, 15 (17 %) featured circumstances beyond the safety system performance and in one loss-of-control crash the driver had disabled the relevant safety system (electronic stability control). The registration years of the cars in our study (2010-17) totaled 3,772,864 and during this period, the cars travelled 75.9 billion kilometers. The crash incidence of the “unavoidable” at-fault fatal crashes was 0.76-0.80 fatal crashes per billion kilometers and 15-16 fatal crashes per million registration years. Conclusions We calculated a crash incidence for the “unavoidable” crashes which was 20–27% smaller than the observed crash rate of ESC-fitted passenger cars in our previous study. We concluded that suicides, active driver input until the crash, and challenging weather and road conditions are the most difficult factors for current active safety systems. Our analysis did not account for issues such as system usability or driver acceptance and therefore our results should be regarded as something that is currently theoretically achievable. However, the observed incidence is a good reference for automated driving development and the crash rate of automated cars.Peer reviewe

Monitoring synaptic transmission in primary neuronal cultures using local extracellular stimulation

Various techniques have been applied for the functional analysis of synaptic transmission in Cultured neurons. Here, we describe a method of studying synaptic transmission in neurons cultured at high-density from different brain regions such as the cortex, striatum and spinal cord. We use postsynaptic whole-cell recordings to monitor synaptic Currents triggered by presynaptic action potentials that are induced by brief stimulations with a nearby extracellular bipolar electrode. Pharmacologically isolated excitatory or inhibitory postsynaptic currents can be reliably induced, with amplitudes, synaptic charge transfers, and short-term plasticity properties that are reproducible from culture to culture. We show that the size and kinetics of pharmacologically isolated inhibitory postsynaptic Currents triggered by single action potentials or stimulus trains depend on the Ca2+ concentration, temperature and stimulation frequency. This method can be applied to study synaptic transmission in wildtype neurons infected with lentiviruses encoding various components of presynaptic release machinery, or in neurons from genetically modified mice, for example neurons carrying floxed genes in which gene expression can be acutely ablated by expression of Cre recombinase. The preparation described in this paper should be useful for analysis of synaptic transmission in inter-neuronal synapses formed by different types of neurons. (c) 2006 Elsevier B.V. All rights reserved

β-TrCP is dispensable for Vpu's ability to overcome the CD317/Tetherin-imposed restriction to HIV-1 release

<p>Abstract</p> <p>Background</p> <p>The cellular transmembrane protein CD317/BST-2/HM1.24/Tetherin restricts HIV-1 infection by physically tethering mature virions to the surface of infected cells. HIV-1 counteracts this restriction by expressing the accessory protein Vpu, yet the mechanism of this antagonism is incompletely understood. β-TrCP is the substrate recognition domain of an E3 ubiquitin ligase complex that interacts with the di-serine motif S52/S56 in the cytoplasmic tail of Vpu to target the CD4 receptor for proteasomal degradation. Recently, it has been suggested that β-TrCP is also critically involved in Vpu's ability to overcome the CD317-mediated virion release block.</p> <p>Results</p> <p>To test this model, we analyzed the consequences of several experimental strategies to interfere with the Vpu-β-TrCP protein-protein interaction. Under these conditions, we studied effects of Vpu on expression and localization of CD317 and CD4, as well as on its ability to promote HIV-1 release. Our results demonstrate a strict requirement for Vpu's di-serine motif for degradation of CD4 and also CD317, reduction of cell surface exposure of CD317, and HIV-1 release enhancement. We further show a critical role of β-TrCP2, but not of the structurally related β-TrCP1 isoform, for Vpu-mediated degradation of both receptors. Most importantly, Vpu remained active in downregulating CD317 from the cell surface and in overcoming the HIV-1 release restriction in β-TrCP-depleted cells.</p> <p>Conclusions</p> <p>These results demonstrate that β-TrCP is not strictly required for Vpu's ability to counteract the CD317-imposed virion release block and support the relevance of cell surface down-modulation of the restriction factor as a central mechanism of Vpu antagonism. Moreover, we propose the existence of a critical, yet to be identified cellular factor that interacts with Vpu via its di-serine motif to alter the trafficking of the restriction factor.</p