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Beyond the palimpsest: Traditions and modernity in urban villages of Shenzhen, China
No full textThis study uses the palimpsest analogy to explore the interactions between traditions and modernity in Chinese urban contexts. Chinese megacities including Shenzhen have undergone continually radical and dramatic transformations. The palimpsest notion, a layered, overwritten surface with traces of earlier content, enables us to unravel historical and cultural layers from the past in the present readings. Shenzhen is then conceptualised as a palimpsest, illustrating its uneven stratification process in which urban villages contain deep descriptive layers, encompassing both traditional myths and futuristic modern ideas. The case study of Pingshan village through a close examination of specific locations via ethnographic mapping demonstrates that each particular space is an accumulation of various ways of palimpsest. This gives a glimpse of the traditions that being handed down and how they intersect with modern influences to produce hybrid spaces. These traditions are the forms of practice embedded in the everyday lives of residents, including long-term villagers and arrived migrants. The study concludes by proposing a framework for creating the potential of hybridisation to inform a more inclusive approach to urban planning and design.Spatial Planning and Strateg
Delay Threshold for Social Interaction in Volumetric eXtended Reality Communication
No full textImmersive technologies like eXtended Reality (XR) are the next step in videoconferencing. In this context, understanding the effect of delay on communication is crucial. This article presents the first study on the impact of delay on collaborative tasks using a realistic Social XR system. Specifically, we design an experiment and evaluate the impact of end-to-end delays of 300, 600, 900, 1,200, and 1,500 ms on the execution of a standardized task involving the collaboration of two remote users that meet in a virtual space and construct block-based shapes. To measure the impact of the delay in this communication scenario, objective and subjective data were collected. As objective data, we measured the time required to execute the tasks and computed conversational characteristics by analyzing the recorded audio signals. As subjective data, a questionnaire was prepared and completed by every user to evaluate different factors such as overall quality, perception of delay, annoyance using the system, level of presence, cybersickness, and other subjective factors associated with social interaction. The results show a clear influence of the delay on the perceived quality and a significant negative effect as the delay increases. Specifically, the results indicate that the acceptable threshold for end-to-end delay should not exceed 900 ms. This article additionally provides guidelines for developing standardized XR tasks for assessing interaction in Social XR environments.Multimedia Computin
PDB2DAT: Automating LAMMPS data file generation from PDB molecular systems using Python, Rdkit, and Pysimm
No full textPdb2dat, developed in Python, is an open-source, self-contained utility that facilitates the conversion of PDB files into LAMMPS data files, catering to the need of initializing atomistic simulation from initial atomic configurations. It extracts molecular details from PDB files, uses Rdkit and Xyz2mol for bonding analysis and 3D conformer generation, and uses Pysimm for assigning force field types and charges. Designed to be lightweight and fully Pythonic, pdb2dat is suitable for use in privilege-limited high-throughput environments. The output details system topologies for use in MD simulations, significantly simplifying the preparatory steps needed by researchers to explore materials phenomena through LAMMPS.Pavement Engineerin
Kunnen tempering van de aanvangshuren en de bereidheid om te investeren in de vrijehuursector samengaan?: Een voorstudie naar de toepassing van de Duitse 'Mietspiegel'
No full textDe ontwerp-Wet Betaalbare Huur die door de minister voor Volkshuisvesting en Ruimtelijke Ordening bij het parlement aanhangig is gemaakt, geeft aanleiding tot verhitte debatten tussen voor- en tegenstanders van de introductie van regulering van aanvangshuurprijzen in een groot deel van wat nu nog de vrije huursector heet. Inmiddels is de wijze waarop in Duitsland van overheidswege de woninghuren worden beïnvloed meermaals genoemd als een goed, zo niet beter, alternatief voor de manier waarop met de ontwerp-Wet Betaalbare Huur beoogd wordt de aanvangshuren in het grootste deel van de huidige vrije huursector te verlagen. Deze constatering was voor Peter Boelhouwer, Arnoud Vlak en Marietta Haffner aanleiding om op basis van de onderzoeksvraag “Kunnen tempering van de aanvangshuren en de bereidheid om te investeren in de vrijehuursector samengaan?” een eerste antwoord te vinden op de vraag of de Duitse aanpak inderdaad een serieus alternatief voor de ontwerp-Wet Betaalbare Huur is.Uit hun voorstudie blijkt dat de Mietspiegel en de Mietpreisbremse tot doel hebben om de scherpe kanten van marktwerking in de vrijehuursector weg te nemen door de ontwikkeling van de aanvangshuren te dempen ten opzichte van hoe deze zich bij volledig vrijlaten daarvan ontwikkelen. Dit laatste gebeurt door de introductie van vergelijkings- of referentiehuren. Deze worden bijgehouden en gepubliceerd in een zogeheten Mietspiegel, een overzicht van huurprijzen geordend naar bepaalde woningkenmerken. In gebieden met een gespannen woningmarkt mag de aanvangshuur van nieuwe huurcontracten niet hoger liggen dan het niveau van de ter plaatse geldende referentie- of vergelijkingshuur vermeerderd met 10% (de Mietpreisbremse). Centrale gedachte is dat de met de Mietpreisbremse ten hoogste toegestane aanvangshuren de trend volgen die aan de ontwikkeling van markthuren ten grondslag ligt. Door de temperende werking op de ontwikkeling van de aanvangshuren draagt een systematiek geënt op de Duitse Mietspiegel in combinatie met de Mietpreisbremse bij aan verbetering van de betaalbaarheid van de aanvangshuren in die delen van de vrije huursector die zich kenmerken door krapte. Deze toekomstige aanvangshuren worden met toepassing van het instrumentarium lager vastgesteld, dan wanneer ze in het geheel vrije spel van vraag en aanbod tot stand zullen komen.Bovendien heeft de combinatie van Mietspiegel en Mietpreisbremse tot gevolg dat aanvangshuren die uitgaan boven de geldende Mietspiegel met opslag als exces worden aangemerkt. Deze situaties kunnen met het reeds bestaande instrumentarium van bijvoorbeeld de Wet Goed Verhuurderschap bestreden worden.Afhankelijk van de beschouwperiode waarover de Mietspiegel wordt berekend én van de hoogte van de opslag die met de Mietpreisbremse voor nieuw af te sluiten huurovereenkomsten ten hoogste wordt toegestaan, is de dempende werking van het instrumentarium groter of juist minder groot.Onmiskenbaar voordeel van het gebruik van een systeem geënt op de Duitse Mietspiegel in combinatie met een Mietpreisbremse is dat het de investeringsbereidheid in vrijesectorhuurwoningen in beginsel niet aantast.Een ander belangrijk voordeel van de Duitse Mietspiegel in combinatie met de Mietpreisbremse is dat het, in tegenstelling tot de ontwerp-Wet Betaalbare Huur, aansluit op de vraag-/aanbodverhouding op de (huur)woningmarkt. En omdat de woningmarkt vooral regionaal wordt bepaald, betekent dit dat het instrument van regio tot regio verschillende uitkomsten heeft. Naar verwachting zal toepassing van een dergelijk systeem in Nederland voor een niet-onbelangrijk deel van de woningmarktregio’s géén effect hebben. In de regio’s waar geen sprake is van krapte op de vrijesector huurwoningmarkt of waar na verloop van tijd de krapte afneemt zullen de aanvangshuren de opslag van de Mietpreisbremse op de Mietspiegel niet halen. Het instrumentarium schakelt zich in zulke situaties vanzelf uit. Het instrumentarium treedt pas weer werking als de krapte toeneemt. Ook dit draagt bij aan de investeringsbereidheid.In tegenstelling tot wat met de ontwerp-Wet Betaalbare Huur wordt beoogd, is het doel van een systematiek geënt op de Duitse Mietspiegel in combinatie met de Mietpreisbremse juist niet om de aanvangshuren in de vrijehuursector per definitie lager dan de markthuur vast te stellen. Dat tast het vertrouwen van investeerders in het door de overheid ten opzichte van de vrijehuursector gevoerde beleid in de kern aan.Ingeval de wetgever van opvatting is dat een systeem geënt op de Duitse Mietspiegel in combinatie met de Mietpreisbremse resulteert in aanvangshuren die nog steeds voor te veel huishoudens onvoldoende betaalbaar zijn, komt als vanzelf de vraag van herintroductie van objectsubsidiëring aan de orde. Objectsubsidiëring brengt de overheid in de positie om van de investeerders die daarop intekenen te vragen de aanvangshuren vast te stellen op niveaus die een te laag rendement geven. In ruil voor deze prestatie draagt de overheid middels subsidiëring bij aan het voor hen benodigde rendement.Real Estate ManagementUrban Development Managemen
Distributing quantum information with holes in germanium
No full textIn this thesis, research is presented that explores the characteristics and possibilities of hole spin qubits defined in quantum dots in a germanium/silicon germanium heterostructure. The results of the most important experiments are concerned with distributing quantum information: either by entangling three qubits as the basis for the phase flip code or by shuttling quantum information encoded in a spin qubit. Chapter 2 gives a brief description of the experimental and theoretical background needed to understand the experiments presented in this thesis. The focus lies on the theory that is specific for hole spin qubits in germanium/silicon germanium, in contrast to electron spin qubits in other semiconductor platforms. In chapter 3, the properties of a two-by-two quantum dot device that could facilitate hole spin qubits are discussed, including shell filling and control over the tunnel coupling between the quantum dots. Chapter 4 provides a detailed discussion of the features of a two-by-two qubit system, showing high-fidelity single qubit gates and the implementation of two-, three-, and four-qubit gates. This two-by-two qubit system is used to implement the Phase flip code, of which the results are shown in chapter 5. To facilitate this, the SWAP, CS−1 and the Toffoli-like gate are demonstrated. Chapter 6 explores the possibilities of diabatically shuttling a hole spin qubit through multiple quantum dots. The effects of spin-orbit interaction and the shuttling performances are described. Finally, Chapter 7 discusses the results presented in this thesis and provides an outlook.QCD/Veldhorst La
Ground-Based Soil Moisture Retrieval Using the Correlation Between Dual-Polarization GNSS-R Interference Patterns
No full textSoil moisture (SM) is an important state variable in land surface models. Here, we investigate the potential of a ground-based global navigation satellite system receiver with two linearly polarized antennas that measure the interference power (IP) of direct and reflected signals in horizontal polarization (H-pol) and vertical polarization (V-pol) to estimate SM. The coefficient of determination between the IP waveforms at H-pol and V-pol ( ) was used as a predictor of SM. A coherent specular reflection model was employed to first explore the relationship between and SM for different values of soil roughness. That relationship was subsequently applied to estimate SM from determined from global positioning system (GPS) signals acquired continuously by a ground-based receiver between May and December 2022 for an area with very smooth bare soil. The results show that the proposed method can estimate the SM of the upper 10-cm layer with high accuracy (with a root-mean-square error (RMSE) of approximately 1.5 vol.%) and demonstrate the potential of the ground-based IP technique as a practical system solution for proximal remote sensing of SM over bare soils .Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Mathematical Geodesy and PositioningGeoscience and Remote Sensin
DeHNSSo: The Delft Harmonic Navier-Stokes Solver for Nonlinear Stability Problems with Complex Geometric Features
No full textA nonlinear Harmonic Navier-Stokes (HNS) framework is introduced for simulating instabilities in laminar spanwise-invariant shear layers, featuring sharp and smooth wall surface protuberances. While such cases play a critical role in the process of laminar-to-turbulent transition, classical stability theory analyses such as parabolized or local stability methods fail to provide (accurate) results, due to their underlying assumptions. The generalized incompressible Navier-Stokes (NS) equations are expanded in perturbed form, using a spanwise and temporal Fourier ansatz for flow perturbations. The resulting equations are discretized using spectral collocation in the wall-normal direction and finite-difference methods in the streamwise direction. The equations are then solved using a direct sparse-matrix solver. The nonlinear mode interaction terms are converged iteratively. The solution implementation makes use of a generalized domain transformation to account for geometrical smooth surface features, such as humps. No-slip conditions can be embedded in the interior domain to account for the presence of sharp surface features such as forward- or backward-facing steps. Common difficulties with Navier-Stokes solvers, such as the treatment of the outflow boundary and convergence of nonlinear terms, are considered in detail. The performance of the developed solver is evaluated against several cases of representative boundary layer instability growth, including linear and nonlinear growth of Tollmien-Schlichting waves in a Blasius boundary layer and stationary crossflow instabilities in a swept flat-plate boundary layer. The latter problem is also treated in the presence of a geometrical smooth hump and a sharp forward-facing step at the wall. HNS simulation results, such as perturbation amplitudes, growth rates, and shape functions, are compared to benchmark flow stability analysis methods such as Parabolized Stability Equations (PSE), Adaptive Harmonic Linearized Navier-Stokes (AHLNS), or Direct Numerical Simulations (DNS). Good agreement is observed in all cases. The HNS solver is subjected to a grid convergence study and a simple performance benchmark, namely memory usage and computational cost. The computational cost is found to be considerably lower than high-fidelity DNS at comparable grid resolutions.AerodynamicsMathematical Physic
18F-Sodium fluoride PET-CT visualizes disease activity in chronic nonbacterial osteitis in adults
No full textChronic nonbacterial osteitis (CNO) is a rare disease spectrum, which lacks biomarkers for disease activity. Sodium fluoride-18 positron emission tomography/computed tomography ([18F]NaF-PET/CT) is a sensitive imaging tool for bone diseases and yields quantitative data on bone turnover. We evaluated the capacities of [18F]NaF-PET/CT to provide structural and functional assessment in adult CNO. A coss-sectional study was performed including 43 adult patients with CNO and 16 controls (patients referred for suspected, but not diagnosed with CNO) who underwent [18F]NaF-PET/CT at our expert clinic. Structural features were compared between patients and controls, and maximal standardized uptake values (SUVmax [g/mL]) were calculated for bone lesions, soft tissue/joint lesions, and reference bone. SUVmax was correlated with clinical disease activity in patients. Structural assessment revealed manubrial and costal sclerosis/hyperostosis and calcification of the costoclavicular ligament as typical features associated with CNO. SUVmax of CNO lesions was higher compared with in-patient reference bone (mean paired difference: 11.4; 95% CI: 9.4–13.5; p < .001) and controls (mean difference: 12.4; 95%CI: 9.1–15.8; p < .001). The highest SUVmax values were found in soft tissue and joint areas such as the costoclavicular ligament and manubriosternal joint, and these correlated with erythrocyte sedimentation rate in patients (correlation coefficient: 0.546; p < .002). Our data suggest that [18F]NaF-PET/CT is a promising imaging tool for adult CNO, allowing for detailed structural evaluation of its typical bone, soft-tissue, and joint features. At the same time, [18F]NaF-PET/CT yields quantitative bone remodeling data that represent the pathologically increased bone turnover and the process of new bone formation. Further studies should investigate the application of quantified [18F]NaF uptake as a novel biomarker for disease activity in CNO, and its utility to steer clinical decision making.RST/Radiation, Science and Technolog
Characterization of Superselective Behavior using DNA Nanostars: Exploring the influence of binding affinity and structural flexibility on DNA nanostar superselectivity
No full textMultivalent interactions are crucial mechanisms employed by cells to respond to their environment, often leading to superselectivity phenomena. Extensive experimental and theoretical efforts have been made to understand the variables controlling superselectivity, but challenges persist in achieving precise control over receptor and ligand numbers in biological systems. To address this, the Laan lab developed a model system using DNA origami, enabling precise manipulation of receptor and ligand numbers at the nanoscale. These nanoscopic (~15 nm) structures can mimic the receptors of a target surface, and the extracellular ligands are represented by a branched star-shaped DNA origami structure in solution. Both structures hold a fluorophore, allowing visualization using total internal reflection microscopy (TIRF) by measuring intensity values of the DNA nanostars absorbed into target surface. In this study, we investigated the effects of altering binding strength and flexibility in DNA nanostar structures on superselectivity. We found that experimental results for replicating previous experiments using the same DNA nanostars (Design A) exhibited minor variations within expected ranges, validating the reliability of the experimental protocol. However, sensitivity analysis highlighted the influence of data points on superselectivity interpretation, emphasizing the need for careful data analysis. Our study also evaluated the impact of introducing sequence mismatches on binding affinity (Design A*), revealing that modifications reducing binding affinity do not necessarily enhance superselective behavior for this system. Additionally, our investigation into the effects of increased flexibility (Design C) revealed unexpected behaviors in bound fraction and cluster formation, suggesting a potential relationship between cluster formation, intensity values registered, and the flexibility of the structure mediated by phase separation. These findings underscore the complexity of DNA nanostar behavior and stress the need for further research to elucidate the factors influencing superselectivity in DNA nanostars. By providing more understanding into how to develop highly selective particles, therapeutic molecules could sharply distinguish between healthy and corrupt cells, leading to customizable treatments with higher efficacy.Applied Sciences | Nanobiolog