Robust Foregrounds Removal for 21-cm Experiments

Direct detection of the Epoch of Reionization via the redshifted 21-cm line will have unprecedented implications on the study of structure formation in the early Universe. To fulfill this promise current and future 21-cm experiments will need to detect the weak 21-cm signal over foregrounds several order of magnitude greater. This requires accurate modeling of the galactic and extragalactic emission and of its contaminants due to instrument chromaticity, ionosphere and imperfect calibration. To solve for this complex modeling, we propose a new method based on Gaussian Process Regression (GPR) which is able to cleanly separate the cosmological signal from most of the foregrounds contaminants. We also propose a new imaging method based on a maximum likelihood framework which solves for the interferometric equation directly on the sphere. Using this method, chromatic effects causing the so-called "wedge" are effectively eliminated (i.e. deconvolved) in the cylindrical ($k_{\perp}, k_{\parallel}$) power spectrum.Comment: Subbmited to the Proceedings of the IAUS333, Peering Towards Cosmic Dawn, 4 pages, 2 figure

Breaking boundaries:Charge density waves, quantum measurement, and black holes in theoretical physics

This thesis, titled “Breaking Boundaries” is a journey through three topics united by the theme of boundaries in physics. First, the journey begins with an investigation into charge density waves (CDWs) and their nearly commensurate phase, focusing on the materials 2H-TaSe2 and 1T-TaS2. An extensive treatment of Ginzburg-Landau theory is covered with an extension into truly two-dimensional systems. This extension is used to study spiral patches of commensurate charge density waves observed in experiment. The research leads to a novel perspective on CDW behaviour with the existence of a spiral CDW phase in a range of materials. Secondly, transitioning to the quantum realm, the thesis addresses the quantum measurement problem, emphasizing the constraints any valid theory must possess. It critiques existing models, demonstrates the non-linearity of objective collapse theories, and proposes a minimal model that bridges quantum mechanics and classical physics. Thirdly, the thesis delves into black holes and specifically the phenomena of thermal radiation due to a horizon. First, we explore analogue models that mimic the thermal spectrum near a black hole horizon, to pave the way to experimental realization. Then we focus on the region far away from a black hole horizon and challenge the notion of remnant radiation at this position. With a theoretical toy model, we study the regime and find a non-evaporating black hole. This questions the validity of standard Hawking radiation calculations.In conclusion, the thesis navigates through the boundaries of material behaviours, the quantum-classical divide, and the enigmatic nature of black holes. It highlights the blurring and breaking of boundaries in physics, offering new perspectives and promising avenues for future discoveries

Toric phakic implantable collamer lens for correction of astigmatism: 1-year outcomes

Erik L MertensMedipolis Eye Centre, Antwerp, BelgiumPurpose: The purpose of this study was to assess predictability, efficacy, safety and stability in patients who received a toric implantable collamer lens to correct moderate to high myopic astigmatism.Methods: Forty-three eyes of 23 patients underwent implantation of a toric implantable collamer lens (STAAR Surgical Inc) for astigmatism correction. Mean spherical refraction was —4.98 ± 3.49 diopters (D) (range: 0 to —13 D), and mean cylinder was —2.62 ± 0.97 D (range: —1.00 to —5.00 D). Main outcomes measures evaluated during a 12-month follow-up included uncorrected visual acuity (UCVA), refraction, best-corrected visual acuity (BCVA), vault, and adverse events.Results: At 12 months the mean Snellen decimal UCVA was 0.87 ± 0.27 and mean BCVA was 0.94 ± 0.21, with an efficacy index of 1.05. More than 60% of the eyes gained ≥1 line of BCVA (17 eyes, safety index of 1.14). The treatment was highly predictable for spherical equivalent (r2 = 0.99) and astigmatic components: J0 (r2 = 0.99) and J45 (r2 = 0.90). The mean spherical equivalent dropped from —7.29 ± 3.4 D to —0.17 ± 0.40 D at 12 months. Of the attempted spherical equivalent, 76.7% of the eyes were within ±0.50 D and 97.7% eyes were within ±1.00 D, respectively. For J0 and J45, 97.7% and 83.7% were within ±0.50 D, respectively.Conclusion: The results of the present study support the safety, efficacy, and predictability of toric implantable collamer lens implantation to treat moderate to high myopic astigmatism.Keywords: phakic intraocular lens, toric implantable collamer lens, astigmatis

Wintergroenten.nl: Teelttips voor groenten onder glas

In de winter worden veel verse groenten vanuit het buitenland ingevoerd. Tegelijkertijd neemt de vraag naar regioproducten toe. In het praktijknetwerk wintergroenten.nl ligt de focus op afzet in de eigen regio en in ruimere zin de regio Nederland. Welke gewassen groeien in de winterperiode in een onverwarmde of licht gestookte kas? Zijn er mogelijkheden voor nieuwe gewassen en worden deze opgenomen door de markt? Om de ervaringen en kennis over de verschillende winterteelten verder te verspreiden is besloten om vanuit het praktijknetwerk deze brochure uit te geven. De nadruk ligt bij de teelt en noodzakelijke teeltkennis over de meest voorkomende winterteelten, maar ook acceptatie vanuit de markt en aandachtspunten bij de afzet van wintergroenten worden hierin meegenomen. Mogelijk stimuleert deze brochure de uitbreiding van biologische winterteelten en daarmee de verbreding van het aanbod in het groenteschap met aantrekkelijke wintergroenten uit eigen regio

Equilibrium Existence and Approximation for Incomplete Market Models with Substantial Heterogeneity

This paper contains an analysis of incomplete market models with finitely but arbitrarily many heterogeneous agents. We discuss the mathematical foundation for equilibrium conditions which leads to two findings. First, we establish existence of equilibria for small and large risks. Second, we develop a simple but general solution technique which handles many state and choice variables for each agent and thus an extremely high-dimensional state space. The method is based on perturbations around a point at which the solution is known. The novel idea is to exploit the symmetry of the problem to overcome the curse of dimensionality. We use the analysis to demonstrate the impact of heterogeneity on macroeconomic quantities and the pricing of risk. Furthermore, we set our technique apart from the standard method used in the literature

Scheduling the installation of the LHC injection lines

The installation of the two Large Hadron Collider (LHC) injection lines has to fit within tight milestones of the LHC project and of CERN's accelerator activity in general. For instance, the transfer line from the Super Proton Synchrotron (SPS) to LHC point 8 (to fill the anti-clockwise LHC ring) should be tested with beam before the end of 2004 since the SPS will not run in 2005. It will first serve during the LHC sector test in 2006. Time constraints are also very strong on the installation of the transfer line from the SPS to LHC point 2 (for the clockwise LHC ring): its tunnel is the sole access for the LHC cryo-magnets and a large part of the beam line can only be installed once practically all LHC cryo-magnets are in place. Of course, the line must be operational when the LHC starts. This paper presents the various constraints and how they are taken into account for the logistics and installation planning of the LHC injection lines

Noise-induced switching between vortex states with different polarization in classical two-dimensional easy-plane magnets

In the 2-dimensional anisotropic Heisenberg model with XY-symmetry there are non-planar vortices which exhibit a localized structure of the z-components of the spins around the vortex center. We study how thermal noise induces a transition of this structure from one polarization to the opposite one. We describe the vortex core by a discrete Hamiltonian and consider a stationary solution of the Fokker-Planck equation. We find a bimodal distribution function and calculate the transition rate using Langer's instanton theory (1969). The result is compared with Langevin dynamics simulations for the full many-spin model.Comment: 15 pages, 4 figures, Phys. Rev. B., in pres