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Subtype-specifieke dendritische herstructurering in retinale ganglioncellen
No full textNeurodegenerative disorders affect an ever-larger group of people. Moreover, they lead to a drastically reduced quality of life, to a large extent because the central nervous system of adult mammals has only a limited capacity to repair itself. Retinal ganglion cells are the neurons that majorly affected in glaucoma and other optic neuropathies. Unraveling the mechanisms involved in the natural ganglion cells developmental growth and the differences and similarities between it and the lack of regrowth in neurodegeneration can provide new insights that are essential to develop new therapeutic strategies for axonal regeneration in the central nervous system. In this project we want to empower in the mouse our innovative hypothesis, which states that dendritic shrinkage contributes to axonal regeneration in order to recapitulate the developmental order and hence attain successful repair. We also want to investigate whether energy transfer via mitochondrial transport could be at the basis of this interaction. First, we will characterize the rules of dendritic growth in retinal ganglion cells during development and their relationship with axonal growth. Next, we will use the retina as a model to investigate similarity between development and recovery from disease, we will demonstrate that the axonal regeneration after optic nerve injury process mimics the events during development, by a correlation between dendrite remodelling and axonal growth. Finally, mitochondrial morphology and transport will be analyzed, and its possible role in stimulating axonal growth will be studied in mouse retinal neurons. This work will unravell mechanisms involved both in development and in neurodegeneration, allowing us to be a step closer to find new therapeutic strategies for axonal regeneration in central nervous system.status: Publishe
Jol-Jomi-Jon: Een Altlas van Publieke Ruimte in Waterlandschappen
No full textThis thesis argues that the planning and design of public space in Dhaka requires a conceptual shift towards a contextualist approach that acknowledges the innate relationship between land and water. Water is the main defining element of Dhaka, but astonishingly hardly recognised in contemporary planning discourses of Dhaka. A conceptual integration of aquatic and terrestrial systems—reframed as a 'blue-green-muddy' network, has the potential to redefine urbanism and public space discourse.
To make this point, the thesis is retracing the history of Dhaka, uniquely through the lens of its water landscape. It specifically investigates the liminal space between water and land. The research does this in 3 main case studies, that are representative for the relationship between city and river, land and water: the Buriganga-Turag River system, the Hatirjheel-Banani-Gulshan integrated lake, and the Balu River. Within these three case studies, the research critically explores liminal spaces as forms of public spaces, spaces produced through the social practices of communities. The exploration is resulting in an atlas of the liminal spaces between water and land in Dhaka that spatially structure a multitude of social practices of communities in Dhaka.
These spaces, shaped by the people who inhabit them, operate outside normative urban design frameworks yet play a critical role in the production of space. By deconstructing public space elements across temporal and spatial scales, this research searches a taxonomy for deltaic public space, that could offer eventually offer a framework for its future integration into urban planning. The alternative and critical reading of liminal spaces developed in the thesis allows indeed to speculate on their potential to reclaim public space in Dhaka.status: Publishe
In defense of categories
No full textsponsorship: Flemish Government, Methusalem funding|METH/24/003, Fonds Wetenschappelijk Onderzoek|G073122Nstatus: Published onlin
The evolution of plasticity and evolvability in a simple gene regulatory network
No full textOrganisms adapt to environmental change by plastic phenotypic responses, genetic adaptation, or a combination of the two. Beyond adapting to the environment, organisms can also evolve the ability to adapt more effectively. Evolution can enhance their capacity to respond to environmental cues (increased plasticity), but also their capacity to harness the effects of mutations (increased evolvability). However, it is unclear how these different adaptive capacities co-evolve. Here, we present an evolutionary simulation study in which a simple gene regulatory network must adapt to various regimes of environmental change. We systematically investigate the evolution of plasticity and evolvability in this network, depending on the speed and predictability of environmental changes, and the reliability of environmental cues. We find that plasticity evolves mostly under fast and erratically changing conditions, especially if cues are reliable. In contrast, evolvability evolves under intermediate environmental variability and lower cue reliability. We zoom in on network architecture to investigate what makes these networks more adaptable, showing that different parts of the network become sensitive to mutations depending on the environmental regime. Overall, our results show that both plasticity and evolvability are readily accommodated even in a simple network, depending on the selective pressures exerted by environmental change.sponsorship: P.vdB. was supported by a KU Leuven start-up grant (STG/21/003). The resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation-Flanders (FWO) and the Flemish Government. (KU Leuven|STG/21/003, Flemish Supercomputer Center, Research Foundation Flanders, Flemish Government)status: Published onlin
Ontwerp en Analyse van Schoeiselantennes voor Draagbare en Lichaamsgebonden Draadloze Systemen
No full textThis doctoral research investigates the design, miniaturization, and implementation of antennas embedded in footwear for wearable and body-centric wireless communication systems. With the increasing demand for high-data-rate, low-latency wireless connectivity in applications such as health monitoring, indoor navigation, and smart wearables, footwear offers a rigid platform for integrating antennas.
The work focuses on two core concepts: constructive mutual coupling and full-duplex operation. First, strongly coupled planar arrays are studied, showing that mutual coupling can be exploited to achieve maximum aperture efficiency and compact high-gain designs. This concept is extended to millimeter-wave (mm-wave) frequencies, resulting in a circularly polarized (CP) array, the first mm-wave antenna successfully integrated into footwear.
Second, the thesis develops self-diplexing and full-duplex antennas capable of simultaneous transmission and reception with high port isolation and harmonic suppression. These designs are further advanced to dual-band self-duplexing structures spanning microwave and mm-wave frequencies. Finally, a self-quadruplexing antenna is presented, operating at four distinct frequency bands (5.8, 7.4, 28, and 38 GHz) using Substrate-Integrated Waveguide (SIW) techniques.
Two designs are validated through simulations, fabrication, and measurements in both free-space and footwear-embedded conditions at mmwave frequencies. The results confirm wide bandwidth, high isolation, compactness, and SAR compliance, establishing practical frameworks for future wearable communication systems. The research demonstrates that compact, efficient, multi-band, and full-duplex antennas can be successfully realized in footwear, opening pathways toward next-generation gigabit-capable smart wearable platforms.status: Publishe
Onderzoeken van aerosol-geassisteerde plasma depositie van biocomposiet antifouling filmen voor biosensing
No full textBiosensor and lab-on-chip devices are revolutionizing modern healthcare as they offer great potential for point-of care diagnostics and various bioanalytical applications. A key challenge in biosensor technology is the development of stable, reliable and reproducible interface chemistries for immobilization of the bioreceptors onto the sensor substrate. At imec, we have explored different surface chemistries, mainly self-assembled monolayers, to ensure a covalent binding of the receptors to biosensor devices. Vapor-phase processes offer a good control of the deposition reaction with less chemical usage and result in uniform coatings in micro-structured substrates or microfluidic channels hereby enhancing the integration compatibility with standard CMOS processing flows. The current limitation of standard CVD and MLD processes is imposed by the low vapor pressure of the precursors that require a too high temperature budget for volatilization. Therefore, in this PhD we want to explore the use of plasma-based depositions of functional coatings in collaboration with the Molecular Plasma Group (MPG)*. MPG offers a technology called atmospheric pressure plasma-enhanced chemical vapor deposition. The use of inert gases such as argon, helium and nitrogen and the use of small quantities of energy at low operating temperatures makes this method environment-friendly and opens the possibility to deposit precursors with a high vapor pressure and to co-deposit different reagents, including intact biomolecules into the deposited layer. By using this technology, I want to deposit uniform thin layers to produce biosensors in a CMOS environment. In view of the large variety of biosensors that is currently investigated, it is likely that no single coating method will suffice for all applications. In order to make the results of this work as widely applicable as possible, the plasma processes will be developped to allow electrochemical detection of inflammatory markers (e.g. C-reactive protein, Tumor Necrosis Factor-α) and detection of metabolites (e.g. glucose, lactose) on selected electrode materials. I will explore the wafer level uniformity, stability and reproducibility, the ability to co-deposit mediators, small molecules and antibodies, the possibilities for area-selective deposition using standard CMOS patterning technologies and/or using optimized nozzle geometries during plasma deposition and finally showcase multiplexed biosensing.status: Publishe
Efficient analysis of production tolerances on static assembly behavior: a flexible multibody approach
No full textsponsorship: The Internal Fund KU Leuven and Research Foundation - Flanders (FWO) (fellowship no. 1266725) are gratefully acknowledged for their support. In addition, this research was partially supported by Flanders Make, the strategic research center for the manufacturing industry. (Flanders Make, KU Leuven)status: Published onlin
HPWP climate, Collective Well-Being, and Firm Performance in SMEs: An Exchange Perspective
No full textResearch on High-Performance Work Practices (HPWP) typically examines employees' aggregated HPWP perceptions and their impact on outcomes. We argue that variability in these perceptions also matters due to its impact on collective exchange relationships. We integrate the aggregated (mean) level HPWP perceptions and variability regarding HPWP perceptions to identify four HPWP climate types: a strong HPWP climate (high mean, low variability) and three weak HPWP climates—unshared high (high variability, high mean), shared low (low variability, low mean), and unshared low (high variability, low mean). Using data from 695 employees in 72 Belgian SMEs, we find that a strong HPWP climate is optimal as it relates to the highest collective social and lowest economic exchange levels, which are – in turn – associated with high collective affective organizational commitment (CAOC) and subjective firm performance. However, it is also linked to high collective exhaustion, showing that aligning organizational and workforce interests is not always possible. As regards the weak climates, they are suboptimal, with shared low climates being particularly detrimental. Even though these climates can be fruitful for firm performance, they are linked to lower levels of CAOC, which can be harmful for SMEs that rely heavily on the effort and engagement of their employees. These findings show that investing in HPWP is fruitful for SMEs, even though they have limited financial means, and that SMEs also need to handle the inherent tensions present in HRM.status: Published onlin
Op weg naar efficiënte terbiumextractie: moleculaire bundels van TbFx voor ISOL en nucleaire geneeskunde
No full textThe goal of this research is to improve the production of radioactive terbium isotopes, which hold great promise for both advanced cancer treatments and diagnostic imaging in nuclear medicine. Four terbium isotopes—¹⁴⁹Tb, ¹⁵²Tb, ¹⁵⁵Tb, and ¹⁶¹Tb—are especially valuable for theragnostic applications, combining therapy and diagnostics and offering a pth towards personalised medicine. However, producing these isotopes in sufficient quantity and purity remains a major challenge..
This work focuses on improving terbium extraction through molecular extraction, specifically by producing terbium fluoride (TbFx) beams that are more volatile. A series of experiments were conducted at CERN's ISOLDE and MEDICIS facilities, using both stable and radioactive targets under extreme conditions typical of Isotope Separation On Line (ISOL) systems. The results demonstrate that terbium can be efficiently extracted though molecular sidebands, opening new possibilities for producing high-purity terbium beams. This research not only provides practical guidance for future production but also lays the groundwork for applying similar methods to other difficult-to-extract elements.
Looking ahead, these findings support the development of large-scale terbium isotope production at next-generation facilities like ISOL@MYRRHA (Belgium) and TATTOOS@PSI (Switzerland).status: Publishe