The feasibility for detection and distinguishing HNLs signals with neutrino signals in IceCube/KM3NeT neutrino telescopes were discussed andWe proposed a distinguishable double tracks events...Show moreThe feasibility for detection and distinguishing HNLs signals with neutrino signals in IceCube/KM3NeT neutrino telescopes were discussed andWe proposed a distinguishable double tracks events geometry and calculated the sensitivity curves by Mathematica. Comparison of the number of events at the lower boundary in KM3NET and CHARM experiments implied IceCube/KM3NeT has no potential for probing this kind of event. We also studied the full decay channels of HNLs and calculated the corresponding sensitivity curves in IceCube and CHARM experiments, excellent agreements were obtained by comparing the numeric sensitivity bounds with the analytic formulas. Further comparison of sensitivity curves of HNLs in both experiments indicates that IceCube has no superiority in HNLs detection. The methods to improve HNLs detection sensitivity in IceCube were also considered, where extension of working time is the most reliable way. Besides, IceCube sensitivity may exceed CHARM by increasing the detector area and/or decay volume length, thus, IceCube gen2 is prospective to contribute to HNLs detection.Show less
The formation of large scale structure e.g. clusters of galaxies has caught plenty of attention lately, since nowadays there exists the technology to collect data with high precision. This implies...Show moreThe formation of large scale structure e.g. clusters of galaxies has caught plenty of attention lately, since nowadays there exists the technology to collect data with high precision. This implies that we might be able to start probing theories that go beyond the simplest single-field inflationary scenario, as an effective single-field theory coming from a two-field inflation framework. In particular, in this work, we study the (scale-dependent) bias in galaxy clustering that comes from an effective field theory, whose effect in the inflaton dynamics is a transient reduction in the speed of sound.Show less
Fluorescence Correlation Spectroscopy (FCS) and F¨orster Resonance Energy Transfer (FRET) are used in combination to study conformational dynamics of biological complexes such as nucleosomes....Show moreFluorescence Correlation Spectroscopy (FCS) and F¨orster Resonance Energy Transfer (FRET) are used in combination to study conformational dynamics of biological complexes such as nucleosomes. However, it is currently unclear how experimental conditions affect the accuracy with which rates of conformational dynamics are determined. We develop a computational method that allows us to simulate FCS data for FRET labelled molecules under Pulsed Interleaved Excitation (PIE). Using these simulations, we determined the effect of experimental conditions such as laser intensity, measurement time, sample concentration and shift in laser focus on the correlation curves and extracted diffusion time and rate of transitions. We show two ways to accurately determine transition rates of diffusing molecules in single experiments. One using PIE and a wavelength dependent correction factor and another under continuous excitation. These simulations can assist in obtaining new insight on protein- DNA interaction studies from combined PIE FRET-FCS studies.Show less
Magnetic Resonance Force Microscopy (MRFM) is a sensitive method to investigate spin systems, which uses a flexible cantilever as mechanical amplifier of the forces on its magnetic tip. However,...Show moreMagnetic Resonance Force Microscopy (MRFM) is a sensitive method to investigate spin systems, which uses a flexible cantilever as mechanical amplifier of the forces on its magnetic tip. However, MRFM is generally limited in its application at milliKelvin temperatures because existing devices rely on laser interferometry to detect cantilever deflection, which heats the cantilever, leaving many condensed matter systems out of reach for MRFM. Furthermore, lower temperatures correspond to lower cantilever force noise, so samples with more diluted spins could be investigated. SQUID-detected MRFM, using the flux induced by a moving cantilever tip, does allow for operation at milliKelvin temperatures. Yet, SQUID-detecting setups have still been limited in sample accessibility because the detection loop is printed on the sample. This thesis reports on the construction of a SQUID-detected MRFM device that employs a single probe head design to overcome the issue. The design choices and assembly methods for this device, called the easyMRFM, are discussed, as well as models to predict the sensitivity. It was found that the coupling is large enough to do optimisations in liquid helium dipstick experiments, although the thermal cantilever motion signal will only barely rise above the flux noise level. Lastly, a room-temperature magnetometry setup for cantilever chips is discussed that has proven useful in characterising cantilevers before mounting them in more permanent setups.Show less
Mechanical forces regulate many cell functions such as differentiation and proliferation. Existing traction force methodology is often limited to measurements in the two-dimensional plane. Recent...Show moreMechanical forces regulate many cell functions such as differentiation and proliferation. Existing traction force methodology is often limited to measurements in the two-dimensional plane. Recent studies have used hydrogel micro-particles to measure cell forces in a complex 3D environment such as a spheroid. However, these micro-particles have not been fully characterised. We show here the synthesis of hydrogel micro particles with size and stiffness similar to cells. We also show that the measured effective Young’s modulus is dependent on the size of the particle measured. The softest beads with a Young’s modulus of 175 Pa can measure normal stresses down to ~ 7.3 Pa. The synthesised beads can be used to determine cell forces in tissues such a tumour spheroids or can be used to mimic cells in tissue layers.Show less
To study the coupling mechanism in high-Tc superconductors we would like to observe them using STM while suppressing the superconductivity with high currents. As the superconductor under study we...Show moreTo study the coupling mechanism in high-Tc superconductors we would like to observe them using STM while suppressing the superconductivity with high currents. As the superconductor under study we choose Bi2S2C1C2O8+x because of easy exfoliatability and doping. Wanting to achieve the required high current densities we decide on lithographically contacting a flake and performing a cleaving in the STM. Several methods are attempted and successful cleaving outside of the STM is achieved. The procedure, however, cannot be reproduced reliably inside the chamber. The journey leading to the result does yield some promising insights to complete the final step.Show less
This study uses the rigid base pair model (rbp) and Markov Chain Monte Carlo (MCMCs) to simulate the unwrapping of nucleosome core particles(NCPs). The model is sequence dependent and is used to...Show moreThis study uses the rigid base pair model (rbp) and Markov Chain Monte Carlo (MCMCs) to simulate the unwrapping of nucleosome core particles(NCPs). The model is sequence dependent and is used to research the bias in left or right unwrapping and the effect of weakening the nucleosome bindings for several DNA sequences (Widom-601, sea urchin 5S gene and 601-derivatives). We are able to focus on intermediate stages in unwrapping, while these may not always be visible in experiments. We validate the model by comparing model outcomes to experimental results and we propose a (simple) method to find interesting sequences for future experiments.Show less
Quantum Spin Hall insulators are particularly attractive materials due to theintrinsic appearance of robust conducting surface states. They represent anew quantum state of matter and offer the...Show moreQuantum Spin Hall insulators are particularly attractive materials due to theintrinsic appearance of robust conducting surface states. They represent anew quantum state of matter and offer the potential of realizing dissipationa-less spin current devices, making them appealing from both a fundamentaland applied point of view. In realistic devices, multiple such states co-existat the surface, but only one pair can be considered ‘topologically’ protectedfrom back-scattering. Thus, the desired robust pair is buried under ‘triv-ial’ conductance. Would the presence of disorder suppress the conductanceof the trivial states, enabling us to capture the topological states? In thisthesis, using a first-principles derived model, we study the effect of disorderon the electronic transport of nanoribbons. Our results show that trivialconductance vanishes for strong enough disorder, and topological protectionsurvives even when a disorder-induced band gap closing occursShow less
The hydrodynamic properties of self-propelled particles have, in the past, been approximated by a multipole expansion. As it becomes easier to produce synthetic swimmers in various shapes and sizes...Show moreThe hydrodynamic properties of self-propelled particles have, in the past, been approximated by a multipole expansion. As it becomes easier to produce synthetic swimmers in various shapes and sizes, a proper understanding of this hydrodynamic basis will likely be important. In this thesis, simulation was used to explore the diusive behavior of the first-order term in the presence of a wall. To quantify this behavior, the characteristic rotation time and eective diusion coecient were determined for a range of values of the first-order expansion coecient . It is shown that for low the particle diuses in three dimensions, while for high alpha it diuses in two dimensions as it is locked parallel to the wall.Show less
Active crystals are a relatively unexplored type of active matter, which could potentially allow for a completely new class of materials. This thesis proposes a system consisting of stainless steel...Show moreActive crystals are a relatively unexplored type of active matter, which could potentially allow for a completely new class of materials. This thesis proposes a system consisting of stainless steel beads in a low-conducting solution of AOT in hexadecane in between two electrodes, to which a high voltage is applied. It presents both theoretical and experimental results for a single bead, showing a voltage range exist for which the beads bounce without reaching the top electrode. These results are used to create a stable bouncing crystal of which the interplay between rigidity and diffusivity is studied. Lastly, this thesis provides suggestions on how to develop the bouncing crystal system further to achieve an active crystal.Show less
In Cosmology, the theories of General Relativity and Quantum Mechanics have to work together very closely. However, the workings of quantum fields in General Relativity are challenging to calculate...Show moreIn Cosmology, the theories of General Relativity and Quantum Mechanics have to work together very closely. However, the workings of quantum fields in General Relativity are challenging to calculate, especially the backreaction of particle production caused by gravitational fields. This can normally only be calculated perturbatively. The theory of Classical-Quantum Correspondence could help with these calculations, as it allows for a single set of equations that covers the full evolution of both fields without the need for perturbations. This is possible by transforming the expectation values of the quantum field to depend on a corresponding classical one. This thesis focuses on the validation this theory of the Classical-Quantum Correspondence for interactions between quantum and gravitational fields. Furthermore we cover simulations of a quantum field in a FRW metric and compare them with simulations of a classical field in the same metric. This shows that the Classical-Quantum Correspondence is a good technique to combine quantum fields with classical gravity, and get the full evolution of both without the need to do the same equation itteratively.Show less
