The fast contribution of visual-proprioceptive discrepancy to reach aftereffects and proprioceptive recalibration

Adapting reaches to altered visual feedback not only leads to motor changes, but also to shifts in perceived hand location; “proprioceptive recalibration”. These changes are robust to many task variations and can occur quite rapidly. For instance, our previous study found both motor and sensory shifts arise in as few as 6 rotated-cursor training trials. The aim of this study is to investigate one of the training signals that contribute to these rapid sensory and motor changes. We do this by removing the visuomotor error signals associated with classic visuomotor rotation training; and provide only experience with a visual-proprioceptive discrepancy for training. While a force channel constrains reach direction 30o away from the target, the cursor representing the hand unerringly moves straight to the target. The resulting visual-proprioceptive discrepancy drives significant and rapid changes in no-cursor reaches and felt hand position, again within only 6 training trials. The extent of the sensory change is unexpectedly larger following the visual-proprioceptive discrepancy training. Not surprisingly the size of the reach aftereffects is substantially smaller than following classic visuomotor rotation training. However, the time course by which both changes emerge is similar in the two training types. These results suggest that even the mere exposure to a discrepancy between felt and seen hand location is a sufficient training signal to drive robust motor and sensory plasticity.York University Librarie

Cluster decomposition, T-duality, and gerby CFT's

In this paper we study CFT's associated to gerbes. These theories suffer from a lack of cluster decomposition, but this problem can be resolved: the CFT's are the same as CFT's for disconnected targets. Such theories also lack cluster decomposition, but in that form, the lack is manifestly not very problematic. In particular, we shall see that this matching of CFT's, this duality between noneffective gaugings and sigma models on disconnected targets, is a worldsheet duality related to T-duality. We perform a wide variety of tests of this claim, ranging from checking partition functions at arbitrary genus to D-branes to mirror symmetry. We also discuss a number of applications of these results, including predictions for quantum cohomology and Gromov-Witten theory and additional physical understanding of the geometric Langlands program.Comment: 61 pages, LaTeX; v2,3: typos fixed; v4: writing improved in several sections; v5: typos fixe

Chromospheric Inversions of a Micro-flaring Region

We use spectropolarimetric observations of the Ca II 8542~\AA\ line, taken from the Swedish 1-m Solar Telescope (SST), in an attempt to recover dynamic activity in a micro-flaring region near a sunspot via inversions. These inversions show localized mean temperature enhancements of $\sim$1000~K in the chromosphere and upper photosphere, along with co-spatial bi-directional Doppler shifting of 5 - 10 km s$^{-1}$. This heating also extends along a nearby chromospheric fibril, co-spatial to 10 - 15 km s$^{-1}$ down-flows. Strong magnetic flux cancellation is also apparent in one of the footpoints, concentrated in the chromosphere. This event more closely resembles that of an Ellerman Bomb (EB), though placed slightly higher in the atmosphere than is typically observed.Comment: 9 pages, 9 figures, accepted in ApJ. Movies are stored here: https://star.pst.qub.ac.uk/webdav/public/areid/Microflare

Design science research with focus groups - a pragmatic meta-model

Purpose – The purpose of this research paper is to present a pragmatic and systematic approach to conduct and document Design Science Research (DSR) activities with Focus Groups (FG), exploring its continuous usage and providing traceability between problem, requirements, solutions, and artifacts. Design/methodology/approach – To conduct the research and produce the meta-model for DSR with FG, a DSR approach was adopted using a conceptual model for Action Design Research already available. The artifact is the result from a specific literature review to define requirements, a careful design, and a refinement stage where it was widely used and tested in real IS implementation projects. Findings – The main outcome of this research is a specific meta-model for DSR with FG, that delivers new insights and practical guidelines for academics and professionals conducting and documenting real-world research and development initiatives deep-rooted in stakeholders’ participation. Rigorous and committed stakeholder engagement is a critical success factor in complex projects. The use of a meta-model enables to increase the process effectiveness, by framing debate and stimulating stakeholders’ participation. Research limitations/implications – The meta-model has been endorsed as a practical and useful artifact by the stakeholders participating in the IS projects where it was adopted. However, to fully demonstrate its capabilities and to become more robust, the model must be further used and tested in other application situations and environments. Originality/value – The usage of Focus Groups (FG) in Design Science Research (DSR) has already been proposed as an effective way, either to study artifacts, to propose improvements in its design, or to acknowledge the utility of those artifacts in field use. The paper provides a sound contribution to this line of research by presenting a meta-model that integrates process and data that may be used by researchers and practitioners to conduct their projects.info:eu-repo/semantics/acceptedVersio

Hydration and anomalous solubility of the Bell-Lavis model as solvent

We address the investigation of the solvation properties of the minimal orientational model for water, originally proposed by Bell and Lavis. The model presents two liquid phases separated by a critical line. The difference between the two phases is the presence of structure in the liquid of lower density, described through orientational order of particles. We have considered the effect of small inert solute on the solvent thermodynamic phases. Solute stabilizes the structure of solvent, by the organization of solvent particles around solute particles, at low temperatures. Thus, even at very high densities, the solution presents clusters of structured water particles surrounding solute inert particles, in a region in which pure solvent would be free of structure. Solute intercalates with solvent, a feature which has been suggested by experimental and atomistic simulation data. Examination of solute solubility has yielded a minimum in that property, which may be associated with the minimum found for noble gases. We have obtained a line of minimum solubility (TmS) across the phase diagram, accompanying the line of maximum in density (TMD). This coincidence is easily explained for non-interacting solute and it is in agreement with earlier results in the literature. We give a simple argument which suggests that interacting solute would dislocate TmS to higher temperatures

Measurement of miniband parameters of a doped superlattice by photoluminescence in high magnetic fields

We have studied a 50/50\AA superlattice of GaAs/Al$_{0.21}$Ga$_{0.79}$As composition, modulation-doped with Si, to produce $n=1.4\times 10^{12}$ cm$^{-2}$ electrons per superlattice period. The modulation-doping was tailored to avoid the formation of Tamm states, and photoluminescence due to interband transitions from extended superlattice states was detected. By studying the effects of a quantizing magnetic field on the superlattice photoluminescence, the miniband energy width, the reduced effective mass of the electron-hole pair, and the band gap renormalization could be deduced.Comment: minor typing errors (minus sign in eq. (5)

Neonatal pneumomediastinum and the spinnaker-sail sign

A male infant was born at 40 weeks of gestation by vacuum-assisted vaginal delivery. Mild respiratory distress with expiratory grunting and subcostal retraction was noted 1 hour after birth. Arterial oxygen saturation remained at more than 95% without the administration of supplemental oxygen. Chest radiography performed 6 hours after birth (Panel A) showed the spinnaker-sail sign, consisting of a large, wedge-shaped opacity extending from the right hemidiaphragm to the superior mediastinum (white arrows), representing thymic tissue displaced from its usual location by a collection of gas under pressure (black arrows). Axial computed tomography of the chest revealed air trapped between the pericardial sac and the thymus, confirming a diagnosis of anterior pneumomediastinum (Panel B, arrow). Named for its visual resemblance to the headsail of a boat, the spinnaker-sail sign occurs with a spontaneous anterior pneumomediastinum and usually resolves without specific treatment. After being observed for clinical and radiographic improvement for 3 weeks, the infant was discharged home in good condition

Stable Umbral Chromospheric Structures

Aims. To understand the morphology of the chromosphere in sunspot umbra. We investigate if the horizontal structures observed in the spectral core of the Ca II H line are ephemeral visuals caused by the shock dynamics of more stable structures, and examine their relationship with observables in the H-alpha line. Methods. Filtergrams in the core of the Ca II H and H-alpha lines as observed with the Swedish 1-m Solar Telescope are employed. We utilise a technique that creates composite images and tracks the flash propagation horizontally. Results. We find 0"15 wide horizontal structures, in all of the three target sunspots, for every flash where the seeing was moderate to good. Discrete dark structures are identified that are stable for at least two umbral flashes, as well as systems of structures that live for up to 24 minutes. We find cases of extremely extended structures with similar stability, with one such structure showing an extent of 5". Some of these structures have a correspondence in H-alpha but we were unable to find a one to one correspondence for every occurrence. If the dark streaks are formed at the same heights as umbral flashes then there are systems of structures with strong departures from the vertical for all three analysed sunspots. Conclusions. Long-lived Ca II H filamentary horizontal structures are a common and likely ever-present feature in the umbra of sunspots. If the magnetic field in the chromosphere of the umbra is indeed aligned with the structures, then the present theoretical understanding of the typical umbra needs to be revisited.Comment: Accepted to Astronomy and Astrophysics. Online material (Fig3.mov and Fig4.mov) will be available at A&

Special Educators Describe the Critical Mass of Co-Teaching

Co-teaching is an instructional approach usually initiated by school administrators to help general and special education teachers who share a single classroom to ensure students with disabilities have access to the general curriculum. Although research regarding co-teaching is still in need of further development in some areas such as student achievement, co-teaching has increasingly grown in popularity as an option for addressing the multiple needs of diverse learners, including students with disabilities. Some school professionals and researchers who are proponents of this instructional delivery model believe that, At the core of co-teaching is determining what instructional techniques will be most efficient and effective in helping all students meet academic standards (Murawski and Dieker, 2004). This study explored the knowledge and skills of special educators related to classroom practices for effective co-teaching. Participants (N=43) were certified special educators from different states around the country. Findings suggest positive relationships between instructional communication and several other variables and may potentially help teacher education candidates develop better skills for delivering general education curriculum along with specially designed services to students with disabilities in co-taught classrooms

Learn what matters: cross-domain imitation learning with task-relevant embeddings

We study how an autonomous agent learns to perform a task from demonstrations in a different domain, such as a different environment or different agent. Such cross-domain imitation learning is required to, for example, train an artificial agent from demonstrations of a human expert. We propose a scalable framework that enables cross-domain imitation learning without access to additional demonstrations or further domain knowledge. We jointly train the learner agent's policy and learn a mapping between the learner and expert domains with adversarial training. We effect this by using a mutual information criterion to find an embedding of the expert's state space that contains task-relevant information and is invariant to domain specifics. This step significantly simplifies estimating the mapping between the learner and expert domains and hence facilitates end-to-end learning. We demonstrate successful transfer of policies between considerably different domains, without extra supervision such as additional demonstrations, and in situations where other methods fail