Beam-Preparation with REXTRAP for the REX-ISOLDE Experiment

REX-ISOLDE is a post-accelerator for radioactive ions located at the ISOLDE facility at CERN. Its task is to accelerate the radioactive ions coming from the on-line mass separator ISOLDE from 60 keV to a final energy of 2.2 MeV/u. To achieve this goal with a compact and cost-efficient setup a new concept was proposed. First the ions are accumulated in a Penning trap (REXTRAP), then the ions are transported to an EBIS (Electron Beam Ion Source), where their charge-state will be increased. Due to the high charge-state of the ions the following linear accelerator can be built comparatively compactly. In the framework of this thesis the construction and commissioning phase of REX-TRAP is described. REXTRAP is a large, gas-filled Penning trap whose aim is to store and cool the radioactive ions coming from ISOLDE. After listing the physics motivation for building REX-ISOLDE and describing its elements, the theory of a Penning trap as well as the setup of REXTRAP is explained. Fi-nally test results for REXTRAP are presented followed by a discussion on how REXTRAP in the present setup can fulfill the demands for the operation of REX-ISOLDE

USING CALLING ACTIVITY TO PREDICT CALLING ACTIVITY: A CASE STUDY WITH THE ENDANGERED HOUSTON TOAD (BUFO [ANAXYRUS] HOUSTONENSIS)

Understanding anuran calling activity patterns is important for maximizing efficiency and value of call survey data collection and analyses. Previous studies have primarily focused on identifying and quantifying abiotic variables that influence anuran calling activity, and investigating relationships between calling activity and population estimates. In this study we investigated the use of a predictor pond approach to guide call survey effort. In this approach, calling activity at a subset of breeding sites (e.g., ponds) is used as a predictor of calling activity at additional breeding sites, with the goal being to minimize sampling effort while simultaneously maximizing sampling efficiency. We explored the efficiency of this approach using call survey data collected on the endangered Houston Toad (Bufo [Anaxyrus] houstonensis) at 15 known breeding ponds over 9 survey years. We found that if calling activity at 3 predictor ponds was used to decide if additional call surveys would occur at the remaining 12 ponds, we would have hypothetically correctly assumed calling activity was not occurring at non-predictor ponds on 92.1% of survey nights, and we would have hypothetically detected 93.9% of the total number of detected individuals over the 9 survey years. We found the predictor pond approach performed well in our case study, and believe it could be a valuable tool for many anuran monitoring programs

Migratory connectivity and spatio-temporal aspects of Pacific Barrow’s goldeneye (Bucephala islandica) migration

Effective management of animals requires understanding movement throughout the annual cycle. We used satellite transmitters to track 229 adult Pacific Barrow’s goldeneye (Bucephala islandica) captured across their full geographic range. We assessed the strength of migratory connectivity and determined latitudinal and sex effects on annual cycle phenology. Male and female goldeneye demonstrated strong migratory connectivity across wintering, breeding, and moulting stages. Males departed breeding grounds before females, spending less time on breeding grounds and more time on moulting grounds. Individuals at northern latitudes spent more time on wintering grounds than individuals at southern latitudes. These results indicate that, within a species, the timing of transitions throughout the annual cycle can vary with both sex and latitude. The spatio-temporal settings in which individuals occur, and the regional associations across annual cycle stages, inform the appropriate scale of management units and the effects of habitat perturbations at different places and times

Taylor Forstner Honors Portfolio

Taylor Forstner\u27s honors portfolio captured in December 2021

Designing a Dyslexia-Friendly Interaction with News Articles

This master's thesis presents a research project focused on improving the accessibility of news articles for people with dyslexia. A significant portion of online news content is text-based, which poses challenges for individuals with reading difficulties. While there are existing digital tools for text simplification and summarization, there is a lack of solutions specifically designed for dyslexic readers, and even fewer adapt to languages other than English. The project addresses this gap with the development of a prototype that generates simplified versions of Norwegian news articles. Adopting a user-centered perspective, qualitative research methods and literature research were conducted to provide a basis for the design process. The later developed prototype aims to provide a flexible model that can accommodate the different reading experiences and perspectives of dyslexic people. Its main functionality lies in visual and content-related text modifications. Together with results from corresponding user tests, the high-fidelity prototype provides detailed findings on how news articles can be made more accessible. They offer insights into the requirements and needs of news consumers with dyslexia and explore the potential of automatic text simplification in this context. The results can benefit companies, institutions, and organizations that are seeking to provide accessible news content, eliminating the need for manual simplification of every article. Moreover, the research conducted in this project can support further studies on design and digital accessibility solutions.Master's Thesis in Interaction and Media DesignMIX350MASV-MI

The stimulating effect of bright light on physical performance depends on internal time.

The human circadian clock regulates the daily timing of sleep, alertness and performance and is synchronized to the 24-h day by the environmental light-dark cycle. Bright light exposure has been shown to positively affect sleepiness and alertness, yet little is known about its effects on physical performance, especially in relation to chronotype. We, therefore, exposed 43 male participants (mean age 24.5 yrs ± SD 2.3 yrs) in a randomized crossover study to 160 minutes of bright (BL: ≈ 4.420 lx) and dim light (DL: ≈ 230 lx). During the last 40 minutes of these exposures, participants performed a bicycle ergometer test. Time-of-day of the exercise sessions did not differ between the BL and DL condition. Chronotype (MSF(sc), mid-sleep time on free days corrected for oversleep due to sleep debt on workdays) was assessed by the Munich ChronoType Questionnaire (MCTQ). Total work was significantly higher in BL (median 548.4 kJ, min 411.82 kJ, max 875.20 kJ) than in DL (median 521.5 kJ, min 384.33 kJ, max 861.23 kJ) (p = 0.004) going along with increased exhaustion levels in BL (blood lactate (+12.7%, p = 0.009), heart rate (+1.8%, p = 0.031), and Borg scale ratings (+2.6%, p = 0.005)) in all participants. The differences between total work levels in BL and DL were significantly higher (p = 0.004) if participants were tested at a respectively later time point after their individual mid-sleep (chronotype). These novel results demonstrate, that timed BL exposure enhances physical performance with concomitant increase in individual strain, and is related not only to local (external) time, but also to an individual's internal time

Two temperature-compensated thermistor current meters for use in marine ecology

Small bead thermistors of the type commonly used for temperature measurement can be adapted for use as current probes in liquid or gaseous media. The small size, the rapid response, and the sensitivity of such probes make them well suited for the study of water movement as a microclimatic factor in marine and limnic habitats...

Preserving neural function under extreme scaling

Important brain functions need to be conserved throughout organisms of extremely varying sizes. Here we study the scaling properties of an essential component of computation in the brain: the single neuron. We compare morphology and signal propagation of a uniquely identifiable interneuron, the HS cell, in the blowfly (Calliphora) with its exact counterpart in the fruit fly (Drosophila) which is about four times smaller in each dimension. Anatomical features of the HS cell scale isometrically and minimise wiring costs but, by themselves, do not scale to preserve the electrotonic behaviour. However, the membrane properties are set to conserve dendritic as well as axonal delays and attenuation as well as dendritic integration of visual information. In conclusion, the electrotonic structure of a neuron, the HS cell in this case, is surprisingly stable over a wide range of morphological scales