Generalized parton distributions of pseudoscalar mesons in a relativistic Bethe-Salpeter framework

The research presented in this PhD dissertation is situated in the field of hadron physics. In this field, it is investigated how strongly interacting particles such as the proton and the pion are built from their elementary constituents, quarks and gluons. The laws obeyed are comprised in the standard model of particle physics. Nevertheless, the interactions between the different building blocks of matter are not entirely understood and a lot of open questions remain. Many of these questions are related to the theory of the strong interaction, which is described in quantum chromodynamics (QCD). In the energy range of hadron physics, QCD is unsolvable. Because the description of hadrons is not feasible in QCD, their inner structure is still not fully understood. One of the questions that remain to be solved, is the origin of the quantum mechanical spin of the nucleon (proton or neutron). In 1997, it was realized that an important contribution to that spin could be calculated through generalized parton distibutions (GPDs). Also for other hadrons, GPDs can be defined and measured. In this dissertation, the pion and kaon GPDs are calculated within the Lorentz covariant Bonn constituent quark model. In this model, a bound quark-antiquark state is described by the Bethe-Salpeter amplitude, which is the solution to the Bethe-Salpeter equation. The thesis describes the analytical derivation of the GPD in the Bonn model, as well as the numerically calculated results

Student perceptions of student support services for first-year engineering students

To help first-year students get accustomed to university, many universities organise intra- and extracurricular support initiatives. During the academic year, student support services at the Faculty of Engineering Technology at KU Leuven offer both course-specific activities as well as initiatives focusing on study career guidance and academic skills. Yet we notice that not all students find their way to these voluntary activities – even if they would benefit from the help. The purpose of this study is (1) to understand how first-year engineering students perceive the student support services, and (2) to understand how we can reach students who need the support, but do not find their way yet. This will further guide us in the development and communication of support activities. A small-scale questionnaire was distributed among first-year engineering students, followed by two focus group discussions. Our findings indicate that support needs are bigger at the start and end of the first semester. Crucial information such as how to study, and communication regarding support activities, should be served more than once, as first-year students still find it hard to filter out the right information. Students prefer course-specific Q&A sessions where they can hear questions of fellow students as well as the answers to those questions. A mentor for study career guidance is well appreciated. Tests and trial exams are important as triggers to start studying. We believe that these findings can inspire colleagues in other institutions

De ontwikkeling van een sociale kaart voor ADHD in de adolescentie en de (jong)volwassenheid

Prospectief onderzoek toont aan dat 30 tot 70% van de kinderen met ADHD problemen blijven vertonen in de volwassenheid. ADHD treft de persoon ook in deze levensfase op vele domeinen en de consequenties voor de directe omgeving en de maatschappij kunnen ernstig zijn. De nood aan betrouwbare diagnostiek, behandeling en ondersteuning in deze groep is duidelijk, het huidige diagnostische, behandelings- en ondersteuningsaanbod daarentegen vaak niet voldoende specifiek en/of gekend. Voor de doelgroep van adolescenten en (jong)volwassenen met (vermoeden van) ADHD is een stoornisspecifieke sociale kaart een noodzaak. Bestaande sociale kaarten bieden al heel wat bruikbare informatie over diensten en instellingen in de welzijns- en gezondheidssector. Het is evenwel vaak moeilijk af te leiden welke specifieke vormen van diagnostiek en begeleiding beschikbaar zijn. Met ondersteuning van de Adviesraad Wetenschappelijk Onderzoek van het sig willen we deze informatie in kaart brengen voor ADHD bij adolescenten en (jong)volwassenen. Concreet werden op basis van een kritische literatuuranalyse richtlijnen voor wetenschappelijk verantwoorde diagnostiek, behandeling en ondersteuning van ADHD na de kindertijd opgesteld. Deze richtlijnen vormen het uitgangspunt van een bevraging van het ADHD-aanbod van verschillende zorginstanties (revalidatiecentra, cggz, COS, MPI, buitengewoon onderwijs, zelfstandige psychologen/psychiaters, instellingen van bijzondere jeugdzorg, kinder- en jeugdpsychiatrie). In het najaar van 2010 wordt deze informatie online beschikbaar gesteld. In deze bijdrage willen we de status van ons initiatief bekend maken en het diagnostisch, behandelings- en ondersteuningsaanbod in Vlaanderen toetsen aan de principes van evidence based practice.status: publishe

Quantifying acromiohumeral distance in overhead athletes with glenohumeral internal rotation loss and the influence of a stretching program

Background: Loss of internal rotation range of motion (ROM) on the dominant side is well documented in athletes performing overhead sports activity. This altered motion pattern has been shown to change glenohumeral and scapular kinematics. This could compromise the subacromial space and explain the association between glenohumeral internal rotation deficit (GIRD) and subacromial impingement. Purpose: First, to quantify acromiohumeral distance (AHD) and compare between the dominant and nondominant side in overhead athletes with GIRD of more than 15 degrees. Second, to investigate the effect of a sleeper stretch program on ROM and AHD. Study Design: Controlled laboratory study. Methods: Range of motion was measured with a digital inclinometer and AHD was measured with ultrasound in 62 overhead athletes with GIRD (>15 degrees) at baseline. Differences between sides were analyzed. Athletes were randomly allocated to the stretch (n = 30) or control group (n = 32). The stretch group performed a 6-week sleeper stretch program on the dominant side. Change of range of motion and AHD were measured and analyzed in both groups after 6 weeks. Results: The dominant side showed a significant internal rotation deficit (-24.7 degrees +/- 6.3 degrees) and horizontal adduction deficit (-11.8 degrees +/- 7.4 degrees) and the dominant side AHD was significantly smaller with the arm at neutral (-0.4 +/- 0.6 mm) and at 45 degrees (-0.5 6 0.8 mm) and 60 degrees (-0.6 +/- 0.7 mm) of active abduction compared with the nondominant side. After stretching, significant increase of internal rotation (113.5 degrees +/- 0.8 degrees), horizontal adduction (110.6 degrees +/- 0.9 degrees) ROM and AHD (+0.5 to +0.6mm) was observed at the dominant side of the stretch group compared with prestretching measurements. No significant change of AHD was seen in the nondominant side of the stretch group and in both sides of the control group. Conclusion: The AHD, a 2-dimensional measure for subacromial space, was found to be smaller on the dominant side in athletes with GIRD and was found to increase after a 6-week sleeper stretch program

Dendritic mitochondrial energy channeling as driver of successful axonal regeneration?

Poster presentation annual Nerf meeting 2018.status: publishe

Helicity amplitudes of nonstrange baryons in the third and fourth resonance region

Baryon resonances with masses around 1600 MeV and higher come into play already at threshold in meson photo- and electroproduction reactions from the proton such as p(gamma(()*()), pi pi)N, p(gamma(()*()), K)Y, P(gamma(()*()), omega)p and p(gamma(()*()), eta)p. We present results for the Q(2) dependence of the helicity amplitudes of these nonstrange baryons resonances, computed in the framework of the Bethe-Salpeter model developed by the Bonn group. The model describes bound states of three relativistic constituent quarks, interacting through an instantaneous linear confining potential and a residual instanton-induced interaction potential. The seven model parameters were fitted to the best known baryon masses, but no extra parameters are introduced in computing the helicity amplitudes

A new microfluidic model to study dendritic remodeling and mitochondrial dynamics during axonal regeneration of adult zebrafish retinal neurons.

Unlike mammals, adult zebrafish are able to fully regenerate axons and functionally recover from neuronal damage in the mature central nervous system (CNS). Decades of research have tried to identify the mechanisms behind their spontaneous regenerative capacity, but the exact underlying pathways and molecular drivers remain to be fully elucidated. By studying optic nerve injury-induced axonal regrowth of adult zebrafish retinal ganglion cells (RGCs), we previously reported transient dendritic shrinkage and changes in the distribution and morphology of mitochondria in the different neuronal compartments throughout the regenerative process. These data suggest that dendrite remodeling and temporary changes in mitochondrial dynamics contribute to effective axonal and dendritic repair upon optic nerve injury. To further elucidate these interactions, we here present a novel adult zebrafish microfluidic model in which we can demonstrate compartment-specific alterations in resource allocation in real-time at single neuron level. First, we developed a pioneering method that enables to isolate and culture adult zebrafish retinal neurons in a microfluidic setup. Notably, with this protocol, we report on a long-term adult primary neuronal culture with a high number of surviving and spontaneously outgrowing mature neurons, which was thus far only very limitedly described in literature. By performing time-lapse live cell imaging and kymographic analyses in this setup, we can explore changes in dendritic remodeling and mitochondrial motility during spontaneous axonal regeneration. This innovative model system will enable to discover how redirecting intraneuronal energy resources supports successful regeneration in the adult zebrafish CNS, and might facilitate the discovery of new therapeutic targets to promote neuronal repair in humans.info:eu-repo/semantics/publishe