Deciding absorption

We characterize absorption in finite idempotent algebras by means of J\'onsson absorption and cube term blockers. As an application we show that it is decidable whether a given subset is an absorbing subuniverse of an algebra given by the tables of its basic operations

Intestinal Absorption

This is the edited transcript of a Witness Seminar held at the Wellcome Institute for the History of Medicine,in London, on 9 February 1999. First published by the Wellcome Trust, 2000. ©The Trustee of the Wellcome Trust, London, 2000.All volumes are freely available online at: www.history.qmul.ac.uk/research/modbiomed/wellcome_witnesses/Annotated and edtied transcript of a Witness Seminar held on 9 February 1999. Introduction by Sir Christopher Booth.Annotated and edtied transcript of a Witness Seminar held on 9 February 1999. Introduction by Sir Christopher Booth.Annotated and edtied transcript of a Witness Seminar held on 9 February 1999. Introduction by Sir Christopher Booth.Annotated and edtied transcript of a Witness Seminar held on 9 February 1999. Introduction by Sir Christopher Booth.A record of a meeting chaired by Lord Turnberg that brought together those from laboratory research and medical practice to discuss some of the key aspects of intestinal absorption, including work on basic physiological mechanisms and techniques, such as the discovery of dedicated transport systems and their localization, and their clinical impact in intestinal disorders and oral rehydration therapy. Participants include: Sir Christopher Booth, Dr Richard Boyd, Professor Ramsey Bronk, Professor Hermon Dowling, Professor Michael Gardner, Dr Michael Hellier, Dr Roy Levin, Professor Richard Naftalin, Professor Timothy Peters, Professor John Walker-Smith and Professor Oliver Wrong. Christie D A, Tansey E M. (eds) (2000) Intestinal absorption, Wellcome Witnesses to Twentieth Century Medicine, vol. 8. London: The Wellcome Trust.The Wellcome Trust is a registered charity, no. 210183

Absorption by Spinning Dust: a Contaminant for High-Redshift 21 cm Observations

Spinning dust grains in front of the bright Galactic synchrotron background can produce a weak absorption signal that could affect measurements of high redshift 21 cm absorption. At frequencies near 80 MHz where the EDGES experiment has reported 21\,cm absorption at $z \approx 17$, absorption could be produced by interstellar nanoparticles with radii $a \approx 50\AA$ in the cold interstellar medium at temperature $T \approx 50$ K. Atmospheric aerosols could contribute additional absorption. The strength of the absorption depends on the abundance of such grains and on their dipole moments, which are uncertain. The breadth of the absorption spectrum of spinning dust limits its possible impact on measurement of a relatively narrow 21 cm absorption feature.Comment: version published in ApJ

Synopsis of Mid-latitude Radio Wave Absorption in Europe

Radio wave absorption data covering almost two years from Europe to Central Asia are presented. They are normalized by relating them to a reference absorption. Every day these normalized data are fitted to a mathematical function of geographical location in order to obtain a daily synopsis of radio wave absorption. A film of these absorption charts was made which is intended to reveal movements of absorption or absorption anomaly. In addition, radiance (temperature) data from the lower D-region are also plotted onto these charts

Soliton absorption spectroscopy

We analyze optical soliton propagation in the presence of weak absorption lines with much narrower linewidths as compared to the soliton spectrum width using the novel perturbation analysis technique based on an integral representation in the spectral domain. The stable soliton acquires spectral modulation that follows the associated index of refraction of the absorber. The model can be applied to ordinary soliton propagation and to an absorber inside a passively modelocked laser. In the latter case, a comparison with water vapor absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with experiment. Compared to the conventional absorption measurement in a cell of the same length, the signal is increased by an order of magnitude. The obtained analytical expressions allow further improving of the sensitivity and spectroscopic accuracy making the soliton absorption spectroscopy a promising novel measurement technique.Comment: 9 pages, 7 figures

Damped Lyman-alpha Absorption Associated with an Early-Type Galaxy at Redshift z = 0.16377

We report new HST and ground-based observations of a damped Lyman-alpha absorption system toward the QSO 0850+4400. The redshift of the absorption system is z = 0.163770 and the neutral hydrogen column density of the absorption system is log N = 19.81 cm**-2. The absorption system is by far the lowest redshift confirmed damped Lyman-alpha absorption system yet identified, which provides an unprecedented opportunity to examine the nature, impact geometry, and kinematics of the absorbing galaxy in great detail. The observations indicate that the absorption system is remarkable in three respects: First, the absorption system is characterized by weak metal absorption lines and a low metal abundance, possibly less than 4% of the solar metal abundance. This cannot be explained as a consequence of dust, because the neutral hydrogen column density of the absorption system is far too low for obscuration by dust to introduce any significant selection effects. Second, the absorption system is associated with a moderate-luminosity early-type S0 galaxy, although the absorption may actually arise in one of several very faint galaxies detected very close to the QSO line of sight. Third, the absorbing material moves counter to the rotating galaxy disk, which rules out the possibility that the absorption arises in a thin or thick co-rotating gaseous disk. These results run contrary to the expectation that low-redshift damped Lyman-alpha absorption systems generally arise in the gas- and metal-rich inner parts of late-type spiral galaxies. We suggest instead that mounting evidence indicates that low-redshift galaxies of a variety of morphological types may contain significant quantities of low metal abundance gas at large galactocentric distances.Comment: 15 pages, LaTex, 4 figures, to be published in The Astronomical Journa

The effect of surface heterogeneity on cloud absorption estimates

This study presents a systematic and quantitative analysis of the effect of inhomogeneous surface albedo on shortwave cloud absorption estimates. We used 3D radiative transfer modeling over a checkerboard surface albedo to calculate cloud absorption. We have found that accounting for surface heterogeneity enhances cloud absorption. However, the enhancement is not sufficient to explain the reported difference between measured and modeled cloud absorption