The Emergence of Gravitational Wave Science: 100 Years of Development of Mathematical Theory, Detectors, Numerical Algorithms, and Data Analysis Tools

On September 14, 2015, the newly upgraded Laser Interferometer Gravitational-wave Observatory (LIGO) recorded a loud gravitational-wave (GW) signal, emitted a billion light-years away by a coalescing binary of two stellar-mass black holes. The detection was announced in February 2016, in time for the hundredth anniversary of Einstein's prediction of GWs within the theory of general relativity (GR). The signal represents the first direct detection of GWs, the first observation of a black-hole binary, and the first test of GR in its strong-field, high-velocity, nonlinear regime. In the remainder of its first observing run, LIGO observed two more signals from black-hole binaries, one moderately loud, another at the boundary of statistical significance. The detections mark the end of a decades-long quest, and the beginning of GW astronomy: finally, we are able to probe the unseen, electromagnetically dark Universe by listening to it. In this article, we present a short historical overview of GW science: this young discipline combines GR, arguably the crowning achievement of classical physics, with record-setting, ultra-low-noise laser interferometry, and with some of the most powerful developments in the theory of differential geometry, partial differential equations, high-performance computation, numerical analysis, signal processing, statistical inference, and data science. Our emphasis is on the synergy between these disciplines, and how mathematics, broadly understood, has historically played, and continues to play, a crucial role in the development of GW science. We focus on black holes, which are very pure mathematical solutions of Einstein's gravitational-field equations that are nevertheless realized in Nature, and that provided the first observed signals.Comment: 41 pages, 5 figures. To appear in Bulletin of the American Mathematical Societ

Develop Guidelines for Pavement Preservation Treatments and for Building a Pavement Preservation Program Platform for Alaska

INE/AUTC 12.0

An exploratory review of current trends in support of eco-DRR

Broquet, M., Cabral, P., & Campos, F. S. (2024). What ecological factors to integrate in landslide susceptibility mapping? An exploratory review of current trends in support of eco-DRR. Progress in Disaster Science, Article 100328. https://doi.org/10.1016/j.pdisas.2024.100328 --- This research was supported by the Portuguese Science Foundation – FCT, under the projects UIDB/04152/2020 – Information Management Research Center (MagIC/NOVA IMS), the European Union-NextGenerationEU, and the Beatriu de Pinós fellowship 2022 – BP 00092 (funded by the Catalan Government and the EU COFUND programme of the Marie Sklodowska-Curie Actions).Ecosystem-based Disaster Risk Reduction (Eco-DRR) reflects the important role that natural ecosystems play in reducing the likelihood, severity, and impact of environmental disasters such as landslides. However, landslide risk assessments often lack explicit references to Eco-DRR and unified frameworks, notably for its Landslide Susceptibility Assessment (LSA). Here, we assess how ecological factors are integrated into LSAs and the feasibility of measuring them, using open Earth Observation (EO) data. We conduct an exploratory review for identifying the factors used in LSAs and ecosystem assessments, determining their commonalities. Key findings indicate that standardization is more lacking in ecosystem assessments than in LSAs, with the former exhibiting a higher dispersion of factors—195 identified across 41 papers—compared to the latter, where only 46 factors were identified across 30 studies. LSAs and ecosystem assessments shared 19 common factors, with only two, the Normalized Differential Vegetation Index (NDVI) and Land Use and Land Cover (LULC), being widely accepted criteria. Our study contributes to advancing Eco-DRR practices by proposing concrete measures to expand the ecological perspective in LSAs and fostering collaboration between DRR and conservation domains. Ultimately, it raises awareness of the pivotal role that healthy ecosystems play in mitigating disasters and addressing societal challenges.publishersversionpublishe

Very-high energy gamma-ray astronomy: A 23-year success story in high-energy astroparticle physics

Very-high energy (VHE) gamma quanta contribute only a minuscule fraction - below one per million - to the flux of cosmic rays. Nevertheless, being neutral particles they are currently the best "messengers" of processes from the relativistic/ultra-relativistic Universe because they can be extrapolated back to their origin. The window of VHE gamma rays was opened only in 1989 by the Whipple collaboration, reporting the observation of TeV gamma rays from the Crab nebula. After a slow start, this new field of research is now rapidly expanding with the discovery of more than 150 VHE gamma-ray emitting sources. Progress is intimately related with the steady improvement of detectors and rapidly increasing computing power. We give an overview of the early attempts before and around 1989 and the progress after the pioneering work of the Whipple collaboration. The main focus of this article is on the development of experimental techniques for Earth-bound gamma-ray detectors; consequently, more emphasis is given to those experiments that made an initial breakthrough rather than to the successors which often had and have a similar (sometimes even higher) scientific output as the pioneering experiments. The considered energy threshold is about 30 GeV. At lower energies, observations can presently only be performed with balloon or satellite-borne detectors. Irrespective of the stormy experimental progress, the success story could not have been called a success story without a broad scientific output. Therefore we conclude this article with a summary of the scientific rationales and main results achieved over the last two decades.Comment: 45 pages, 38 figures, review prepared for EPJ-H special issue "Cosmic rays, gamma rays and neutrinos: A survey of 100 years of research

Determinants Of Barries To Quality Of Direct Foreign Investments Evidences From South & East Asian Economies

The objective of this paper is to examine whether FDI inflows in South & East Asian economies posses any barriers which are deterring to attract FDI of their actual potential? If so, what are those various set of barriers? These questions are addressed in this study using cross section time series data for 17 South and East Asian economies from 1996 to 2005.http://deepblue.lib.umich.edu/bitstream/2027.42/64376/1/wp910.pd

STROBE-X: X-ray Timing and Spectroscopy on Dynamical Timescales from Microseconds to Years

We present the Spectroscopic Time-Resolving Observatory for Broadband Energy X-rays (STROBE-X), a probe-class mission concept selected for study by NASA. It combines huge collecting area, high throughput, broad energy coverage, and excellent spectral and temporal resolution in a single facility. STROBE-X offers an enormous increase in sensitivity for X-ray spectral timing, extending these techniques to extragalactic targets for the first time. It is also an agile mission capable of rapid response to transient events, making it an essential X-ray partner facility in the era of time-domain, multi-wavelength, and multi-messenger astronomy. Optimized for study of the most extreme conditions found in the Universe, its key science objectives include: (1) Robustly measuring mass and spin and mapping inner accretion flows across the black hole mass spectrum, from compact stars to intermediate-mass objects to active galactic nuclei. (2) Mapping out the full mass-radius relation of neutron stars using an ensemble of nearly two dozen rotation-powered pulsars and accreting neutron stars, and hence measuring the equation of state for ultradense matter over a much wider range of densities than explored by NICER. (3) Identifying and studying X-ray counterparts (in the post-Swift era) for multiwavelength and multi-messenger transients in the dynamic sky through cross-correlation with gravitational wave interferometers, neutrino observatories, and high-cadence time-domain surveys in other electromagnetic bands. (4) Continuously surveying the dynamic X-ray sky with a large duty cycle and high time resolution to characterize the behavior of X-ray sources over an unprecedentedly vast range of time scales. STROBE-X's formidable capabilities will also enable a broad portfolio of additional science

The Union of Regeneration: the Anti-Bolshevik Underground in Revolutionary Russia, 1917-1919

PhDThe Union of Regeneration has been chosen as the main focal point of this thesis, a study of underground political organisations in revolutionary Russia who came about as a result of fragmentation of Russia's major political parties in 1917 and sought to oppose the Bolshevik takeover of power. The thesis traces the origins of the underground in the political turmoil of 1917 before detailing how each group was formed, and how a number of plans were made, most of which hinged on the extensive involvement of Allied interventionist forces, to form an anti-Bolshevik and anti-German front in the wake of the signature of the Treaty of Brest-Litovsk. The efforts of the Union of Regeneration, the National Centre, and other groups such as the Union for the Defence of the Fatherland and Freedom are presented as a series of failures which took place mostly in 1918. By examining the reasons for each of these failures, this thesis hopes to focus not on external factors, such as the lack of Allied intervention to assist the underground groups or the machinations of reactionary forces against them, in order to reveal the fundamental failings of the underground movement as a whole. The underground lacked any organisational discipline or coherence, its ranks were easily entered on a loose, `personal' basis and there was little unity of purpose between its members, save the removal of Soviet power. Consequently, plans made were too vague, agreements were too easily broken, and alliances were too easily ruptured. This thesis, then, hopes to demonstrate that although when considered together the anti-Bolshevik underground constituted a genuine potential threat to the Bolshevik regime, that it failed to act as one contributed greatly to it being easily marginalised by the extremes of left and right

Towards in vivo g-ratio mapping using MRI: unifying myelin and diffusion imaging

The g-ratio, quantifying the comparative thickness of the myelin sheath encasing an axon, is a geometrical invariant that has high functional relevance because of its importance in determining neuronal conduction velocity. Advances in MRI data acquisition and signal modelling have put in vivo mapping of the g-ratio, across the entire white matter, within our reach. This capacity would greatly increase our knowledge of the nervous system: how it functions, and how it is impacted by disease. This is the second review on the topic of g-ratio mapping using MRI. As such, it summarizes the most recent developments in the field, while also providing methodological background pertinent to aggregate g-ratio weighted mapping, and discussing pitfalls associated with these approaches. Using simulations based on recently published data, this review demonstrates the relevance of the calibration step for three myelin-markers (macromolecular tissue volume, myelin water fraction, and bound pool fraction). It highlights the need to estimate both the slope and offset of the relationship between these MRI-based markers and the true myelin volume fraction if we are really to achieve the goal of precise, high sensitivity g-ratio mapping in vivo. Other challenges discussed in this review further evidence the need for gold standard measurements of human brain tissue from ex vivo histology. We conclude that the quest to find the most appropriate MRI biomarkers to enable in vivo g-ratio mapping is ongoing, with the potential of many novel techniques yet to be investigated.Comment: Will be published as a review article in Journal of Neuroscience Methods as parf of the Special Issue with Hu Cheng and Vince Calhoun as Guest Editor

Compact Stars in the QCD Phase Diagram

The book edition of the Universe Special Issue “Compact Stars in the QCD Phase Diagram” is devoted to the overarching aspects shared between heavy-ion collisions and compact star astrophysics in investigating the hadron-to-quark matter phase transition in the equation of state of strongly interacting matter in different regions of the phase diagram of QCD. It comprises 22 review and research articles that, together, will serve as a useful guide in educating both young and senior scientists in this emerging field that represents an intersection of the communities of strongly interacting matter theory, heavy-ion collision physics and compact star astrophysics