Sound Field Analysis of Rooms with Ceiling Absorbers

The theory on damped modes and absorption of modes with grazing incidence presented by Kinsler et al. has been applied to the shoebox-shaped room with five hard walls and one absorber wall, using measurements in a scale model box. Single mode reverberation time analysis, estimations of reverberation time based on grazing mode absorption via measurements of the specific acoustic impedance, and measurements of vertical components of the sound intensity has all been used in an attempt at identifying grazing modes and comparing the theoretical descriptions to the observed sound field. The thesis found Kinsler et al.'s theory on damped modes and absorption of modes with grazing incidence to be poorly suited for the shoebox-shaped room with five hard walls and one absorber wall. Grazing modes and non-grazing modes were not separable, neither by reverberation time estimates nor by sound intensity measurements. The reverberation time estimates using the damped modes & grazing mode absorption theory were several orders of magnitude less than the observed reverberation time. The most likely weakness in the theory is thought to be the assumption on wall impedance, which does not fit with porous absorbers on rigid walls

Deformation, Phyllonitization and Associated Element Mobilization of Granitoid Rocks: - A geochemical study of the Fagervika granitoid, Norway.

The Fagervika granitoid is a felsic, peraluminous intrusion that was emplaced in oceanic crust at 481 Ma, now represented as the Bymarka ophiolite in Trondheim, Norway. It belongs to the Støren Group in the Upper Allochthon within the Scandinavian Caledonides. The emplacement onto the Baltican margin during the Caledonian orogeny occurred around 420 Ma, with following collapse in 400 - 380 Ma. Regionally, the rocks have been subjected to greenschist to lower amphibolite facies metamorphic conditions. Detailed mapping at centimetre to decimetre scale of the Gråkallen area reveals the complex distribution of phyllonitic shear zones hosted by a granodiorite, with transport direction interpreted as a top-to-the-west movement. Field observations and petrographic studies were performed for mineral identification and textural descriptions. Comparison of the modal mineralogy with whole-rock data including trace elements is used to show chemical variation between the different lithologies. Mineral chemistry was examined with element mapping by Scanning Electron Microscopy (SEM), Electron Microprobe Analysis (EMPA) and Laser Ablation Inductively Coupled Mass Spectrometry (LA-ICP-MS). These methods report the major and trace element distribution along with the Rare Earth Elements (REE) distribution in each mineral phase. Isocon analysis of paired granodiorite-phyllonite samples enabled for quantification of the gains and losses in the system. The rocks at Gråkallen are granodioritic, with only minor variations in modal mineralogy across all samples. The granodiorite is hypidiomorphic, show no preferred mineral orientation with early growth of mica and dynamic recrystallization of quartz. Phyllonitic shear zones have developed locally in the granodiorite and signs of widespread fluid interaction and metasomatism is evident throughout the rocks. The granodioritic assemblage is represented by Qtz + Pl + Kfs + Ms ± Py, with secondary accessories Ep + Aln + Ttn, which has been identified as the main REE-carriers. Allanite is enriched in the LREE, while epidote contains LREE to a lesser degree and titanite holds the HREEs, reflecting each minerals preferential affinity for the REEs. The feldspars are altered, with alkali feldspar neocrystallized to albite, and plagioclase is seritized and saussuritized, with widespread muscovite and epidote. Major elements Na and K have been mobilized and Ca to a lesser degree, while the REEs has only been mobilized at micro scale in the granodiorite. iii The phyllonitic shear zones trend approximately N-S and consist of elongated quartz grains in a muscovite matrix, defining the assemblage of Qtz + Ms ± Py ± feldspar porphyroclasts. The formation of the muscovite indicates the presence of water-rich fluid. The Ca-bearing accessories Ep + Aln + Ttn has been destabilized, along with most of the feldspar due to deformation and high fluid/rock ratio, though some titanite is remnant. In addition, the fluid composition enabled for mobilization of trace elements and REEs. This resulted in depletion of the REE, with a greater loss of LREE compared to HREE. An epidote-rich shear zone shows a high modality of epidote, along with Ms + Py + Qtz + Ttn, with subsequent REE enrichment in comparison to the granodiorite. The REE pattern of the epidote-rich shear zone appeared as an enriched version of the granodiorite REE pattern, suggesting that stabilization of epidote and titanite prevented loss of the REEs. This study shows that metasomatism triggered mineralogical changes and grain size reduction, especially for the feldspars in the undeformed granodiorite, enabling increased fluid flow. The heightened fluid/rock ratio allows muscovite to form, and thus promoting strain weakening and further strain partitioning. Deformation and fluid-rock interaction completely changed the mineralogy by destabilizing feldspar and the REE-bearing phases and by forming muscovite, which promoted mobilization of K, Na, Ca and the REEs during phyllonitization of the granodiorite

A genetically encoded reporter of synaptic activity in vivo

To image synaptic activity within neural circuits, we tethered the genetically encoded calcium indicator (GECI) GCaMP2 to synaptic vesicles by fusion to synaptophysin. The resulting reporter, SyGCaMP2, detected the electrical activity of neurons with two advantages over existing cytoplasmic GECIs: it identified the locations of synapses and had a linear response over a wider range of spike frequencies. Simulations and experimental measurements indicated that linearity arises because SyGCaMP2 samples the brief calcium transient passing through the presynaptic compartment close to voltage-sensitive calcium channels rather than changes in bulk calcium concentration. In vivo imaging in zebrafish demonstrated that SyGCaMP2 can assess electrical activity in conventional synapses of spiking neurons in the optic tectum and graded voltage signals transmitted by ribbon synapses of retinal bipolar cells. Localizing a GECI to synaptic terminals provides a strategy for monitoring activity across large groups of neurons at the level of individual synapses

Determining the neurotransmitter concentration profile at active synapses

Establishing the temporal and concentration profiles of neurotransmitters during synaptic release is an essential step towards understanding the basic properties of inter-neuronal communication in the central nervous system. A variety of ingenious attempts has been made to gain insights into this process, but the general inaccessibility of central synapses, intrinsic limitations of the techniques used, and natural variety of different synaptic environments have hindered a comprehensive description of this fundamental phenomenon. Here, we describe a number of experimental and theoretical findings that has been instrumental for advancing our knowledge of various features of neurotransmitter release, as well as newly developed tools that could overcome some limits of traditional pharmacological approaches and bring new impetus to the description of the complex mechanisms of synaptic transmission

Programmeringsoppgaver i Kikora: En studie av Kognitive Krav, Oppgavetype, Affordances & Constraints

Denne studien har sett på programmeringsoppgaver på 9. trinn i det digitale læreverket Kikora med fokus på kognitive krav, oppgavetyper og affordances og constraints. Gjennom en grundig analyse av to temaer, Fra blokk til tekstprogrammering og Programmere Pytagoras, ble det identifisert viktige funn. Analysen avslørte at det er en betydelig overvekt av oppgaver som krever lavere nivåer av kognitiv tenkning, spesielt innenfor kategorier som memorering og prosedyrer uten sammenhenger. Imidlertid var det mangel på oppgavetyper som lar eleven skape egne koder, forklare hvordan koder fungerer med egne ord og oppgavetyper som lar elevene lage hypoteser om hva som kommer til å skje når en kode kjøres. En viktig begrensning som ble påpekt, var mangelen på formativ evaluering. Tilbakemeldinger begrenset seg i stor grad til å vurdere om oppgaven var løst riktig eller ikke, og kunne ikke gi innsikt i elevenes prosess eller misoppfatninger. På den positive siden ble fordelen av selvrettende oppgaver understreket, noe som sparer tid for lærerne, men samtidig begrenser deres evne til å identifisere elevenes utfordringer. Konklusjonen indikerer at det er behov for en større variasjon av oppgavetyper som utfordrer høyere nivåer av kognitiv tenkning for å støtte både programmeringskompetanse og kritisk tenkning blant elevene. Denne studien fokuserer på kun to temaer som utgjør en liten del av programmeringsoppgavene, og gir dermed også en begrenset innsikt i Kikoras programmeringsoppgaver.This study has investigated programming tasks for 9th-grade students within the digital learning platform Kikora, with a focus on cognitive requirements, types of tasks, and affordances and constraints. Through a thorough analysis of two themes, From Block to Text Programming and Programming Pythagoras, significant findings were identified. The analysis revealed a significant prevalence of tasks that require lower levels of cognitive thinking, especially within categories such as memorization and context-less procedures. However, there was a lack of task types that allow students to create their own code, explain how code works in their own words, and task types that enable students to make hypotheses about what will happen when code is executed. An important limitation that was pointed out was the lack of formative assessment. Feedback was largely limited to assessing whether the task was solved correctly or not and could not provide insight into students' processes or misconceptions. On the positive side, the benefit of self-assessing tasks was emphasized, which saves time for teachers but at the same time limits their ability to identify students' challenges. The conclusion indicates the need for a greater variety of task types that challenge higher levels of cognitive thinking to support both programming skills and critical thinking among students. This study focuses on only two themes, which constitute a small part of the programming tasks in Kikora, thus providing limited insight into Kikora's programming tasks

Ultrastructural and functional fate of recycled vesicles in hippocampal synapses

Efficient recycling of synaptic vesicles is thought to be critical for sustained information transfer at central terminals. However, the specific contribution that retrieved vesicles make to future transmission events remains unclear. Here we exploit fluorescence and time-stamped electron microscopy to track the functional and positional fate of vesicles endocytosed after readily releasable pool (RRP) stimulation in rat hippocampal synapses. We show that most vesicles are recovered near the active zone but subsequently take up random positions in the cluster, without preferential bias for future use. These vesicles non-selectively queue, advancing towards the release site with further stimulation in an actin-dependent manner. Nonetheless, the small subset of vesicles retrieved recently in the stimulus train persist nearer the active zone and exhibit more privileged use in the next RRP. Our findings reveal heterogeneity in vesicle fate based on nanoscale position and timing rules, providing new insights into the origins of future pool constitution

Sound Field Analysis of Rooms with Ceiling Absorbers

The theory on damped modes and absorption of modes with grazing incidence presented by Kinsler et al. has been applied to the shoebox-shaped room with five hard walls and one absorber wall, using measurements in a scale model box. Single mode reverberation time analysis, estimations of reverberation time based on grazing mode absorption via measurements of the specific acoustic impedance, and measurements of vertical components of the sound intensity has all been used in an attempt at identifying grazing modes and comparing the theoretical descriptions to the observed sound field. The thesis found Kinsler et al.'s theory on damped modes and absorption of modes with grazing incidence to be poorly suited for the shoebox-shaped room with five hard walls and one absorber wall. Grazing modes and non-grazing modes were not separable, neither by reverberation time estimates nor by sound intensity measurements. The reverberation time estimates using the damped modes & grazing mode absorption theory were several orders of magnitude less than the observed reverberation time. The most likely weakness in the theory is thought to be the assumption on wall impedance, which does not fit with porous absorbers on rigid walls

A Synaptic Mechanism for Temporal Filtering of Visual Signals

The visual system transmits information about fast and slow changes in light intensity through separate neural pathways. We used in vivo imaging to investigate how bipolar cells transmit these signals to the inner retina. We found that the volume of the synaptic terminal is an intrinsic property that contributes to different temporal filters. Individual cells transmit through multiple terminals varying in size, but smaller terminals generate faster and larger calcium transients to trigger vesicle release with higher initial gain, followed by more profound adaptation. Smaller terminals transmitted higher stimulus frequencies more effectively. Modeling global calcium dynamics triggering vesicle release indicated that variations in the volume of presynaptic compartments contribute directly to all these differences in response dynamics. These results indicate how one neuron can transmit different temporal components in the visual signal through synaptic terminals of varying geometries with different adaptational properties

Dendritic position is a major determinant of presynaptic strength

Different regulatory principles influence synaptic coupling between neurons, including positional principles. In dendrites of pyramidal neurons, postsynaptic sensitivity depends on synapse location, with distal synapses having the highest gain. In this paper, we investigate whether similar rules exist for presynaptic terminals in mixed networks of pyramidal and dentate gyrus (DG) neurons. Unexpectedly, distal synapses had the lowest staining intensities for vesicular proteins vGlut, vGAT, Synaptotagmin, and VAMP and for many nonvesicular proteins, including Bassoon, Munc18, and Syntaxin. Concomitantly, distal synapses displayed less vesicle release upon stimulation. This dependence of presynaptic strength on dendritic position persisted after chronically blocking action potential firing and postsynaptic receptors but was markedly reduced on DG dendrites compared with pyramidal dendrites. These data reveal a novel rule, independent of neuronal activity, which regulates presynaptic strength according to dendritic position, with the strongest terminals closest to the soma. This gradient is opposite to postsynaptic gradients observed in pyramidal dendrites, and different cell types apply this rule to a different extent

Tectonomagmatic evolution of the Sveconorwegian orogen recorded in the chemical and isotopic compositions of 1070–920 Ma granitoids

The Sveconorwegian Province in Southern Norway and Sweden hosts at least four granitoid suites, representing apparently continuous magmatism at the SW margin of the Fennoscandian Shield between 1070 and 920 Ma. This study presents a compilation of published and new zircon LA-ICP-MS U-Pb geochronology, whole-rock and zircon geochemistry and Sm-Nd isotope data for the granitoid suites and demonstrates the granitoids’ ability to record changes in the tectonomagmatic evolution of this orogenic Province. The Sirdal Magmatic Belt (SMB, ca. 1070–1010 Ma) represents the earliest magmatism, west in the Province, followed by two hornblende-biotite granitoid suites (HBG, ca. 1000–920 Ma) and the Flå–Iddefjord–Bohus suite (FIB, ca. 925 Ma), in central and eastern parts of the Province, respectively. The SMB and the HBG bodies located outside of the SMB (referred to as HBGout) are chemically similar, whereas the HBG bodies located in the same region as the SMB (referred to as HBGin) are more ferroan, enriched in incompatible elements and have higher zircon saturation temperatures. Isotopically, the SMB and both HBG suites fall on an evolutionary trend from widespread 1.5 Ga crust in the region, suggesting this was the dominant crustal contribution to magmatism. The FIB suite is more peraluminous, rich in inherited zircon, and has isotopic compositions suggesting a more evolved source than both the HBG suites and the SMB. Trace element modelling shows that the SMB and HBGout suites could have formed by 50% partial melting of 1.5 Ga crust, whereas 5–10% remelting of the dehydrated and depleted SMB residue accounts for the geochemical composition of the HBGin suite. The available data suggest a scenario where the 1.5 Ga lower crust underwent melting due to long-lived mafic underplating giving rise to the SMB suite. After ca. 1000 Ma, regional-scale extension may have led to more widespread mafic underplating causing remelting of the residue following SMB melt extraction, forming the HBGin suite, with lower-crustal melting farther east forming the HBGout suite. Changes in melt composition over this 150 Myr time interval may thus be ascribed to an evolving melt source rather than fundamental changes in tectonic regime. Deep continental subduction at ca. 990 Ma, east in the orogen, provided an isotopically evolved crustal source for the FIB suite. The data underline the difference in tectonic processes across the orogen, with long-lived, high temperatures in the western and central parts and colder, high-pressure events in the eastern parts of the orogen