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Absorption (logic)

About: Absorption (logic) is a research topic. Over the lifetime, 5733 publications have been published within this topic receiving 236302 citations.


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Journal ArticleDOI
TL;DR: These benchmark values provide a test of QED in the smallest neutral molecule, and they open up an avenue to resolve the proton radius puzzle, as well as constrain putative fifth forces and extra dimensions.
Abstract: Weak transitions in the (2,0) overtone band of the hydrogen deuteride molecule at $\ensuremath{\lambda}=1.38\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ were measured in saturated absorption using the technique of noise-immune cavity-enhanced optical heterodyne molecular spectroscopy. Narrow Doppler-free lines were interrogated with a spectroscopy laser locked to a frequency comb laser referenced to an atomic clock to yield transition frequencies [$R(1)=217105181895(20)\text{ }\text{ }\mathrm{kHz}$; $R(2)=219042856621(28)\text{ }\text{ }\mathrm{kHz}$; $R(3)=220704304951(28)\text{ }\text{ }\mathrm{kHz}$] at three orders of magnitude improved accuracy. These benchmark values provide a test of QED in the smallest neutral molecule, and they open up an avenue to resolve the proton radius puzzle, as well as constrain putative fifth forces and extra dimensions.

83 citations

Journal ArticleDOI
TL;DR: In this article, the authors report results from thirteen X-ray bright BL Lacertae objects, selected from the {\it Einstein} Slew Survey sample, and find significant evidence for intrinsic curvature (steepening by $d\Gamma / d({\rm log} E) = 0.4 \pm 0.15$).
Abstract: We report results from {\it XMM-Newton} observations of thirteen X-ray bright BL Lacertae objects, selected from the {\it Einstein} Slew Survey sample. The survey was designed to look for evidence of departures of the X-ray spectra from a simple power law shape (i.e., curvature and/or line features), and to find objects worthy of deeper study. Our data are generally well fit by power-law models, with three cases having hard ($\Gamma<2; dN/dE \propto E^{-\Gamma}$) spectra that indicate synchrotron peaks at $E \gsim 5$ keV. Previous data had suggested a presence of absorption features in the X-ray spectra of some BL Lacs. In contrast, none of these spectra show convincing examples of line features, either in absorption or emission, suggesting that such features are rare amongst BL Lacs, or, more likely, artifacts caused by instrumental effects. We find significant evidence for intrinsic curvature (steepening by $d\Gamma / d({\rm log} E) = 0.4 \pm 0.15$) in fourteen of the seventeen X-ray spectra. This cannot be explained satisfactorily via excess absorption, since the curvature is essentially constant from $0.5-6$ keV, an observation which is inconsistent with the modest amounts of absorption that would be required. We use the {\it XMM-Newton} Optical Monitor data with concurrent radio monitoring to derive broadband spectral energy distributions and peak frequency estimates. From these we examine models of synchrotron emission and model the spectral curvature we see as the result of episodic particle acceleration.

83 citations

Posted Content
TL;DR: In this article, the authors give a new proof for the existence conjecture for combinatorial designs, based on the method of iterative absorption, which has its roots in the 19th century.
Abstract: In a recent breakthrough, Keevash proved the Existence conjecture for combinatorial designs, which has its roots in the 19th century. We give a new proof, based on the method of iterative absorption. Our main result concerns $K^{(r)}_{q}$-decompositions of hypergraphs whose clique distribution fulfils certain uniformity criteria. These criteria offer considerable flexibility. This enables us to strengthen the results of Keevash as well as to derive a number of new results, for example a resilience version and minimum degree version.

83 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reconstruct a 3D tomographic map of the foreground Ly$\alpha$ forest absorption at $2.2
Abstract: Using moderate-resolution optical spectra from 58 background Lyman-break galaxies and quasars at $z\sim 2.3-3$ within a $11.5'\times13.5'$ area of the COSMOS field ($\sim 1200\,\mathrm{deg}^2$ projected area density or $\sim 2.4\,h^{-1}\,\mathrm{Mpc}$ mean transverse separation), we reconstruct a 3D tomographic map of the foreground Ly$\alpha$ forest absorption at $2.2

83 citations

Journal ArticleDOI
TL;DR: An extended x-ray-absorption fine structure study has been carried out on a range of rare-earth metaphosphate glasses of growing interest in optical communications and laser technologies, showing no evidence for R-R correlations within the short-range order.
Abstract: An extended x-ray-absorption fine structure (EXAFS) study has been carried out on a range of rare-earth metaphosphate $R{(\mathrm{P}{\mathrm{O}}_{3})}_{3}$ glasses of growing interest in optical communications and laser technologies. Phosphate glasses modified using the rare-earth oxides ${\mathrm{Pr}}_{6}$${\mathrm{O}}_{11}$, ${\mathrm{Nd}}_{2}$${\mathrm{O}}_{3}$, ${\mathrm{Eu}}_{2}$${\mathrm{O}}_{3}$, ${\mathrm{Gd}}_{2}$${\mathrm{O}}_{3}$, ${\mathrm{Tb}}_{2}$${\mathrm{O}}_{3}$, and ${\mathrm{Ho}}_{2}$${\mathrm{O}}_{3}$, have been investigated using their respective rare-earth ${L}_{\mathrm{III}}$ absorption edges. The data provide information on the local environment of the rare-earth ion within the phosphate glass matrix constructed from linked P${\mathrm{O}}_{4}$ tetrahedra. The rare-earth ions occupy sites with an average coordination number in the range, $6l~Nl~8$, the surrounding atoms being oxygen. The first shell interatomic distance over the range of rare-earth ions establishes the rare-earth contraction of ionic radii with increasing atomic number in a series of glasses. There is also evidence for a rare-earth-phosphorus correlation between 2.7 and 3.6 \AA{}, and a further rare-earth-oxygen correlation at approximately 4 \AA{}. The EXAFS spectrum shows no evidence for R-R correlations within the short-range order, a result especially pertinent to the optical and magnetic properties of the glasses. The fractal dimensionality 4${\mathrm{C}}_{11}$/B of these glasses, obtained from the elastic stiffnesses determined from ultrasonic wave velocities, ranges between 2.3 and 2.8, indicating that their connectivity tends towards having a three-dimensional character.

83 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2021290
2020249
2019220
2018230
2017162
2016163