General Physical Features Research Articles

General theory of spectral diffusion and echo decay in glasses.

The general physical features and a mathematical description of spectral diffusion in glasses at low temperatures is considered. The condition is found for when spectral diffusion can be treated as a Markovian process. The physical reason for the Lorenzian form of a two-level system spectral line shape is considered. For the case when spectral diffusion is not Markovian it can be described by a distribution functional or a characteristic functional. The evaluation of the characteristic functional is reduced to solving a differential equation of second order and the evaluation of an integral. The theory is applied to two-pulse and three-pulse echo decay. The relationship between the theoretical results and available experimental data is discussed.

Physical and chemical aspects of Chew Valley and Blagdon Lakes, two eutrophic reservoirs in North Somerset, England

SummaryChew Valley and Blagdon Lakes are two shallow, hard‐water, lowland eutrophic reservoirs, situated near Bristol in the south‐west of England.Chew Lake is more turbid and richer in plankton but poorer in macrophytes than Blagdon, and is more exposed to wind action. Both lakes show evidence of transient stratification in the summer coupled to deoxygenation of the bottom water, which has led to release of nutrients from the sediments.Severe algal blooms in Chew Lake in 1968 and the consequent filtration difficulties led to the establishment of a collaborative research programme between the University of Bristol and the Bristol Waterworks Company, to define the present biological status of the lakes, and to predict their possible future development. The work covers a wide range of measurements and observations on the limnological conditions of the lakes, which form an elegantly contrasted pair, and this paper describes their general physical and chemical features.

The Dye-Staining of Micro-Organisms: A Review

The staining of micro-organisms is an essential feature of microscopy and is also an important aspect of solution adsorption. The present article is an attempt to arouse the interest of physical chemists in the subject of staining mechanisms, which has been to some extent neglected. The general physical and chemical features of the cells of micro-organisms are described in broad terms. The more common staining techniques are described and their mechanisms discussed from the chemist's point of view.

Canada

A STUDE of the geography of Canada was much needed by students, who have little access to any objective consideration of that country. Prof. Griffith Taylor has supplied this want in great measure. The book is based on extensive travels in many parts of Canada and also in Newfoundland, which is included in the volume. Part 1 treats of the position, discovery and general physical features, including climate ; part 2 considers the Dominion by natural regions ; part 3 is a study of environments as related to man—a careful consideration of occupations and population problems. The whole is illustrated by a wide range of sketch maps and diagrams, many of which show great ingenuity.

The Geology of Vanua Levu 1

VANUA LEVU, one of the two principal islands in the Fiji archipelago, according to Mr. Guppy's summary of previous investigations, has received less notice than Viti Levu, or even some of the smaller islands. The late Prof. Dana made a small collection of. its rocks in 1840, and published some observations on. its geology. It was visited in 1878 by Mr. J. Home, of Mauritius, but no collections were made by him, by the Challenger, or by investigators under the direction of Prof. A. Agassiz, so that it offered a very promising field of research, which occupied Mr. Guppy for two years. The results, so far as concerns its geological and general physical features, and the petrology of its rocks, are described in the present volume, with reproduced photographs and other illustrations.

Glacial lakes of Minnesota

Research Article| January 01, 1901 Glacial lakes of Minnesota N. H. WINCHELL N. H. WINCHELL Search for other works by this author on: GSW Google Scholar GSA Bulletin (1901) 12 (1): 109–128. https://doi.org/10.1130/GSAB-12-109 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation N. H. WINCHELL; Glacial lakes of Minnesota. GSA Bulletin 1901;; 12 (1): 109–128. doi: https://doi.org/10.1130/GSAB-12-109 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract IntroductionThe reviewing and abstracting of the chapters of the final report of the Geological Survey of Minnesota, so far as they treat of the areal geology of the state, have brought vividly to mind some of the general physical features which have not been grouped nor discussed in their ensemble in any of the chapters of that report. Among these data, which are scattered through the volumes of that report, none stand out more boldly than those pertaining to the drift. After the moraines the glacial lakes are perhaps the most remarkable and most interesting phenomena among the drift features.In the course of the geological survey most of these lakes have been referred to—at least in respect to some of their features—and some of them have been carefully examined and described. Most of them, however, have not been mapped nor named. The attempt is here made to bring . . . This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.

2. The Geology of the Faröe Islands

The author visited the Faröe Islands last summer in company with Mr Amund Helland of Christiania. They made various traverses across the largest and most important islands, and touched here and there at several of the smaller ones. They have constructed a geological map of the group, upon which is shown the outcrop of the coal-seams of Suderöe, the direction of numerous dykes of basalt, the position of great intrusive sheets of the same rock; and the trend of the glaciation is indicated by arrows. The introductory part of this paper gives some account of the geological observations made by previous writers—Jorgen Landt in 1800, Mackenzie and Allan in 1815, Trevelyan a year or two later, Forchhammer in 1824, Robert Chambers in 1854, and Johnstrup in 1873. The general physical features of the islands are next described, the extent of land being roughly estimated at about 600 square miles.

The Solution of the Nile Problem

I HAVE read with much pleasure Mr. Keith Johnston's remarks in your impression of the 27th ult. on the subject of Dr. Livingstone's explorations, not only because they manifest an intimate acquaintance with the general physical features of the field of inquiry and a proper estimate of the merits of the question; but because they help to establish the correctness of my opinion, that the Chambeze and its lakes belong to the Nile system, and not to that of the Congo. I have only to explain that, in my letter of December 1st (NATURE, No. 9), I did not “give the opinion that the river which forms the main part of the great traveller's latest discoveries is the head stream of the Nile,” but merely said that it “joins” it.

On the Carboniferous Limestone of Oreton and Farlow, Clee Hills, Shropshire

§ 1. The general physical and palseontological features of the small district referred to in these notes having been carefully and clearly described by Sir Roderick Murchison in his classic work ‘The Silurian System,’ the additional facts which a visit paid to it during the past autumn enables us to record may be considered simply as a continuation of those previously observed. The thin beds of limestone which form the basement of the Titterstone Clee Coal-field are well exposed in a marginal flexure of the strata north-eastward of the hill, at Oreton and Farlow, and also, at a somewhat higher level, around its southern abutments. Our observations upon the character of the beds and their fossil contents have bcen confined to the exposures in the first-named localities. The geographical relations of this limestone ridge with the nearlying millstone-grit and coal-measurcs, in their turn covered up by the sheets of erupted basalt which form the high summits of the Clee, are well scen from the igneous knoll of Kinlet, three miles to the emstward. § 2. Immediately below the summit of the ridge at Farlow, and on the northern side, is a quarry of yellow sandstone, from which recently a large quantity of stone has been obtained for the rebuilding of the church. It is a thick-bedded, fine-grained sandstone, having ripple-marked surfaces, and occasionally containing disseminated pebbles of quartz. The colour of the stone is a pale yellow, in places slightly stained by ferruginous oxidation. Remains of fossil Fishes were first