Probing the Local Interstellar Medium with Scintillometry of the Bright Pulsar B1133+16

The interstellar medium hosts a population of scattering screens, most of unknown origin. Scintillation studies of pulsars provide a sensitive tool for resolving these scattering screens and a means of measuring their properties. In this paper, we report our analysis of 34 yr of Arecibo observations of PSR B1133 + 16, from which we have obtained high-quality dynamic spectra and their associated scintillation arcs, arising from the scattering screens located along the line of sight to the pulsar. We have identified six individual scattering screens that are responsible for the observed scintillation arcs, which persist for decades. Using the assumption that the scattering screens have not changed significantly in this time, we have modeled the variations in arc curvature throughout the Earth's orbit and extracted information about the placement, orientation, and velocity of five of the six screens, with the highest-precision distance measurement placing a screen at just ${5.46}_{-0.59}^{+0.54}$ pc from the Earth. We associate the more distant of these screens with an underdense region of the Local Bubble

Challenges in Quasinormal Mode Extraction: Perspectives from Numerical solutions to the Teukolsky Equation

The intricacies of black hole ringdown analysis are amplified by the absence of a complete set of orthogonal basis functions for quasinormal modes. Although damped sinusoids effectively fit the ringdown signals from binary black hole mergers, the risk of overfitting remains, due to initial transients and nonlinear effects. In light of this challenge, we introduce two methods for extracting quasinormal modes in numerical simulations and qualitatively study how the transient might affect quasinormal mode fitting. In one method, we accurately fit quasinormal modes by using their spatial functional form at constant time hypersurfaces, while in the other method, we exploit both spatial and temporal aspects of the quasinormal modes. Both fitting methods leverage the spatial behavior of quasinormal eigenfunctions to enhance accuracy, outperforming conventional time-only fitting techniques at null infinity. We also show that we can construct an inner product for which the quasinormal eigenfunctions form an orthonormal (but not complete) set. We then conduct numerical experiments involving linearly perturbed Kerr black holes in horizon penetrating, hyperboloidally compactified coordinates, as this setup enables a more precise isolation and examination of the ringdown phenomenon. From solutions to the Teukolsky equation, describing scattering of an ingoing gravitational wave pulse, we find that the contributions from early-time transients can lead to large uncertainties in the fit to the amplitudes of higher overtones ($n\geq 3$) when the signal is fitted over a short time interval. While the methods we discuss here cannot be applied directly to data from merger observations, our findings underscore the persistence of ambiguities in interpreting ringdown signals, even with access to both temporal and spatial information

Research and Application on the Dynamic Protection Approach using in the Historic residential Blocks Renewal

In this paper, the main research question is How can the Dynamic Protection approach be used for the renewal of the historic residential block and make the old living areas become full of vitality? The historic residential block is a part of historic district, and it mainly refers to the block in which the buildings have mainly the residential function in the past, and even today they still retain the living function as its main function. The community, historical significance, size and built density, distinguishable features and identity, continuity, strong vitality, and diversity are the main characteristics of the historic residential block. the use value is the basic value of historic residential block, and together with the historic value and cultural value, make up very important features of the historic residential block, that should be carefully considered during the renovation process. I argue here that by the dynamic protection approach, the attractiveness and vitality lacking in many of these neighborhoods could be brought into the historic residential block again. The dynamic protection approach emphasizes the sustainable, organic and small-scaled renovation of historic residential block and it focuses on the protection of the intangible cultural heritages as well as the tangible heritages in the block. The goal of dynamic protection approach is to stimulate the development potential of the block itself and restore the vitality to the block, make the block not only well protected, but also re-adapted to the development of the modern city. Therefore, I consider that the dynamic protection approach is suitable for the renovation of historic residential block. In order to explore the application of the dynamic protection in practice, I use a case study approach as my research method. In order to explore the application of dynamic protection approach in a Chinese historic residential block, I conducted a design proposal of the historic residential block in Xijindu historic district, Zhenjiang, my case study, as an application case. I concluded through my case study and the design proposal that the dynamic protection has strong operational value in practice

The Impact of Wind-Driven Rain on Surface Waterproofed Brick Cavity Walls

Moisture ingress is a major cause of damage to masonry cavity walls. Products of various chemical compositions are available for wall surface treatment, aimed at reducing/eliminating water ingress. This study presents the results of full-scale wall tests designed to quantify water absorption into uninsulated and insulated brick masonry cavity walls exposed to wind-driven rain (WDR) with and without surface waterproofing. Two different waterproofing products were used: acrylic and silane–siloxane mixture. Untreated and treated walls were exposed to cycles consisting of 10 min wetting at 2.25 L/m2·min every 60 min. The results show that both treatments lead to a reduction in water ingress ranging from 90% to 97%. However, while a more consistent performance was obtained for the silane/siloxane-treated walls under repeated exposure, the results for the acrylic treatment were dominated by the original wall conditions, improved with a reapplication of the treatment. The testing protocol proposed in this study is effective in determining the performance of waterproofing treatments exposed to different levels of WDR. Both treatments prove to be effective in preventing moisture uptake in walls in moderate WDR exposure conditions, while in extreme WDR exposure conditions, the acrylic treatment is less effective

New algorithm for isometric embedding of black hole horizons

Isometric Embedding is a classic problem in differential geometry and general relativity that involves constructing a surface in Euclidean space described by a metric tensor. The results from this problem have a long history for visualization, but are also relevant for calculating quantities like black hole mass and energy. Unfortunately, in general scenarios, this problem requires a solver capable of handling a system of strongly nonlinear and nonstandard PDEs, for which there is no generally established algorithm. We have explored a radically new approach to the embedding problem, applying it to a variety of specific test cases and confirming that the results converge as expected and agree with results obtained analytically and by other algorithms. This presentation describes this novel algorithm and results of a finite-difference-based C++ code that we have written to implement and test it

In-situ study of the structure and dynamics of thermo-responsive PNIPAAm grafted on a cotton fabric

Stimuli-responsive polymeric materials can adapt to various surrounding environments, converting chemical and biochemical changes into optical, electrical and thermal signals, or changing wettability and adhesion properties upon external stimuli. Herein we report a cotton fabric modified with a thermo-responsive polymer, Poly(N-isopropylacrylamide) (PNIPAAm). 1H solid-state NMR techniques were used to characterize the molecular structure and dynamics of the PNIPAAm brushes, while still grafted on the cotton fabric surfaces, avoiding un-grafting destructive procedures. The results demonstrate that the motion of the grafted PNIPAAm brushes is restricted as the temperature rises above the low critical solution temperature (LCST), which was estimated to be ~34 °C. Variable temperature (VT) experiments were used to investigate the nature of the hydrophilic-hydrophobic transitions of the grafted polymer. The 1H solid-state NMR techniques used proved to be an extremely sensitive and precise way to probe in-situ the LCST transition of the PNIPAAm brushes, while still grafted on cotton fibres. This work presents a high potential synthesis and analysis route towards stimuli-responsive cotton fibres which can find exceptional applications as novel intelligent fabrics for the textile related industries