Aggregate Movement Research Articles

SLOW MOVEMENT OF SLOPE MATERIALS THROUGH THE PROCESS-ES OF FREEZING AND THAWING IN THE NORTHERN PART OF ASHIO MOUNTAINS, JAPAN

The purpose of this research is to make clear the processes of movement of slope materials occuring through freezing and thawing. A studied area belongs to Nikko National Park in the central part of Honshu, Japan. Seven slopes were selected for the observation and measurement in the area. The followings were observed and measured : 1) longitudinal profiles of slopes, 2) features and depth of frozen slope materials, 3) water content of slope materials before and during the period of freezing, 4) displacement caused by the processes of freezing-thawing and by other factors such as changes in soil temperature, soil moisture, etc. In addition, a laboratory experiment was carried out in order to carry out a further examination of the processes of movement of slope materials caused by, freezing-thawing. The seven slopes are all in the natural conditions. Two of them have a convex profile while the others have a convex-concave profile. The mean inclination of these slopes ranges from 28 to 41 degrees. The frozen materials can be classified into following seven types : 1) ice layer, 2) ice layer bearing soil lens, 3) frozen soil bearing lens-like ice crystals, 4) frozen soil bearing short needle-like ice crystals, 5) concrete-like frozen soil, 6) frozen soil bearing cubic ice crystals in pores, 7) frozen soil bearing jam-like ice. The frost penetration into the slope materials generally shows a trend of increase in depth downslope. The water content has no change in the directions normal to and parallel to the slope surface during the non-frost period.It was observed that water increment had occurred toward the surface from inward during the frost period, and this phenomena had taken place up to the depth less than 12.5 cm. An improved Young-pit method was used to measure the displacement of slope material. This is different from the original Young-pit method in such a way that the top of pin was painted and displacement was traced on white paper. The rate of downslope displacement in each slope increases in general at the middle and/or the foot of slope. The depth in which displacement can be recognized is less than 12.5 cm on each slope. Furthermore, the dis-placement distribution is classified into four types. From the field observation and the laboratry experiment, several considerations were given to the processes of movement of slope materials occurring through freezing and thawing. These are summarized as follows. 1) Comparing the result obtained in the period of frost with that in the non-frost period, the movement of the slope mantle originated by freezing and thawing is different from that caused by other factors in the direction and the rate of displacement. 2) According to the observation of changes in soil moisture in the process of thawing of a frozen soil, the downslope displacement can be explained by the inter movement of soil aggregates in the thawing layers. 3) It is anticipated that the slope material would move downslope until soil aggregates make contact with each other in the process of thawing. 4) The maximum rate of the downslope displacement of slope mantles through the proces-ses of freezing and thawing appears at a certain range of slope angles, from 32 to 37 degrees. This range of slope angle is considered to be a critical angle in this study.

Erythrocyte settling.

The mechanism of erythrocyte settling has been observed directly by microscope. The results have been correlated with the standard method of measuring erythrocyte sedimentation rate (E.S.R.) and with theories of the settling of suspensions. Downward movement of cells and aggregates causes rapid upward currents in the suspending medium carrying with them other cells and smaller aggregates that may collide and result in attachment or break-up. The fall of the interface at the top of the cell column has three phases: (a) an initial acceleration, (b) a long phase at a constant rate of fall and (c) a deceleration phase as the aggregates pack at the bottom of the tube. During phases a and b, the aggregate size at the top of the column is constantly increasing to reach saturation when the interface meets the pile-up of cells at the bottom of the chamber, when phase c starts. The results for cells suspended in Ringer's solution, in which there is no aggregation, are compatible with the theory of "hindered settling" of slurrys in the chemical engineering literature. Settling in plasma is complicated by the formation and break-up of aggregates during settling, and will require a more elaborate theory.

Productivity: Taylorism Revisited (Round Three)

Saturday Review published in January 1972 six articles which explored the growing unreality and dehumanization some call it irrelevance of economic theory and analysis.1 The statement is nowhere more applicable than to the subfield of economics, labeled microeconomics, which deals with the individual calculations of producers and consumers within market systems. Macroeconomics, conversely, deals with aggregate movements in income and output, and it is in this area that economics, as a discipline and as a tool of public policy, has registered its presumed accomplishments. The macroeconomists, moreover, are the best-known economists (Paul Samuelson, Milton Friedman, and those who join the Council of Economic Advisers). As John Kenneth Galbraith has made so clear, economists recognize but make no attempt to reconcile profound contradictions between the two subfields; conventional textbooks pronounce inefficient those individual market systems dominated by a few large producers (the oligopolies, or bellwether industries), but the same textbooks describe the overall economy as having proved itself efficient (through growth).2 It is worth noting that all the management fads derived from economic thinking come from microeconomics (where inefficiency supposedly runs rampant); that is where we got the favorite of the 1960's, systems analysis, and the currently popular concepts of evaluation and productivity. As was the case with systems analysis, few are spending much time examining the underlying premises of the models they use. To do so would expose those premises for the anomalies they are, and it would demonstrate to all of us that little of useful

Chemotaxis and the early stages of aggregation in cellular slime molds

We consider here the effect of aggregative movement on organizing wave propagation in the cellular slime molds. We start by formulating chemotactic response in a way that is susceptible to quantitative treatment. Next we report a series of quantitative results on chemotactic aggregative movements obtained from observations and subsequent theoretical analysis. Perhaps the most important of these are that the chemotactic signal is impulsive, i.e. short compared to the duration of the response, that the response is of the all-or-none variety, and that differences in period between Dictyostelium discoideum and Polysphondylium violaceum are compensated by differences of chemotactic response to give comparable aggregation territories. An explicit formula is derived for the density changes produced by the chemotactic response to the periodic signals and their effect on the wave propagation discussed. The most startling effect is an appreciable Doppler shift of the apparent frequency of the signal as seen by those amebae having a chemotactic response different from the average. The shift may be important for understanding the efficiency of entrainment by the center of all amebae in its territory.

What can Mathematical Models Tell us About Occupational Mobility?*

A description is given of most models and methods which have recently been proposed for describing aggregate movement over a set of occupational categories, both during a single interval of time and over a sequence of intervals; contingency tables and Markov chains are emphasized. Substantial movement (in an aggregate sense) is “explained” by simple effects of supply, demand, age of respondent, etc., without knowledge of nondemographic variables such as respondent's education, aspirations, etc. Related but unpublished findings by the author and others are given and numerous possible directions for investigation are suggested.

Discussion: The moisture movement of natural aggregate and its effect on concrete

Discussion: The moisture movement of natural aggregate and its effect on concrete

Interplay of mutant and wild-type pigment cells in chimeric leopard frogs

The semidominant mutant gene burnsi ( B) suppresses the formation of the dorsal spots (aggregations of dermal melanophores) that confer upon the wild-type frog ( Rana pipiens) its characteristic leopard-like pattern. Mutant action was appraised by analyzing the interaction of contiguous burnsi and wild-type tissues in experimentally produced chimeric frogs. Two embryos in early tailbud development, one burnsi ( Bb) and the other wild-type ( bb), were each cut in half across the middle of the body, and the genetically different front halves were interchanged. Twenty-four chimeric embryos were carried through and beyond metamorphosis, of which 13 comprised the union of anterior burnsi halves to posterior wild-type halves (burnsi:wild-type) and 11 represented the reverse fusion (wild-type:burnsi). The primary objective was to deduce whether factors endogenous or exogenous to the spot-forming melanophores are primarily responsible for the difference in mutant and wild-type pigmentary patterns. It appears that the mutant burnsi gene alters principally the intrinsic properties of the melanoblasts. That the pigment cell is modified in some way by the mutant gene is suggested by the failure, to a variable extent, of wild-type melanoblasts to form spots in the posterior half of a burnsi:wild-type chimeric frog. A provisional interpretation is that burnsi propigment cells infiltrate the posterior wild-type terrain and inhibit or curtail the aggregative movements of the wild-type melanoblasts. The antagonistic influences of the burnsi melanoblasts may wane as they complete their differentiation. Accordingly, some of the wild-type pigment cells, previously held in abeyance, may then satisfy their inherent tendency to congregate into spots. In the reciprocal chimeric combination, wild-type:burnsi, it is likely that the wild-type melanoblasts invade the burnsi terrain. Once again, impeditive activities of resident burnsi melanoblasts apparently prevent the emigrant wild-type pigment cells from fulfilling their aggregative potential. It may be thought that an accessory inhibiting factor is some unfavorable condition in the tissue environment of the melanoblasts, but data from other lines of inquiry indicate that the burnsi environmental tissue is suitable for the differentiation of wild-type melanoblasts.

Activity manifestations of Hassall's corpuscles in vitro as revealed by cinematography.

Thymic explants from newborn rats were cultivated in Rose chambers under dialysis membranes. With the use of phase contrast, time-lapse cinematography, the following activity manifestations were observed: 1. Several corpuscles showed rotatory movements; 2. nuclear rotation was observed in some cells of the corpuscles; 3. some individual cells in the 15-day culture showed pulsatile activity which might be involved in the mechanism of the rotatory movements of the cellular aggregates; 4. the corpuscles increased in size by the addition of cells and/or by mitosis; 5. the elements at the periphery of the more mature corpuscles (7- and 9-day cultures) were viable, while the central area appeared to be composed of necrotic tissue or hyalinized material.

Effect of Moisture Movement of Natural Aggregate on Concrete

Effect of Moisture Movement of Natural Aggregate on Concrete

The moisture movement of natural aggregate and its effect on concrete

Summary This paper summarizes the background and development of the work carried out at the Scottish Lahoratory of the Building Research Station on the quality of concrete prepared from various aggregates. It establishes that many natural crushed rock and gravel aggregates undergo changes of volume, to a greater or lesser extent, as they take up or lose water, and shows how this characteristic influences the shrinkage and durability of concrete in which they are incorporated.

Productivity in Canada

An interesting analysis of productivity in Canada from 1931 to 1949 has recently been published by Mr. A. Maddison in the Economic Journal. Mr. Maddison admits, however, that his choice of dates, which was limited by the lack of official estimates of the employed labour force prior to 1931, is unfortunate in that a strong cyclical influence colours the results. To overcome this difficulty calculations have been made of the employed labour force prior to 1931 (see Table III), thus extending the period that can be covered back to 1926. In addition this paper makes use of revised and more complete data published by the Dominion Bureau of Statistics. No attempt is made to duplicate Maddison's excellent summary of the diverse factors contributing to productivity, or his brief look at inter-industry shifts, except for the very important shift of labour from agricultural to non-agricultural employment. But more emphasis is placed on aggregate movements during particular periods and on the comparison of productivity in Canada with that in the United States. In brief, the two papers are complementary, and should be so considered.Productivity is, of course, an elusive concept when applied to operations of more than one industry, or even to more than one line of production. Is an automobile, for example, really worth 1,000 bushels of wheat in terms of economic value, and is the productivity of a farmer low because he can produce only 2,600 bushels of wheat in a year on 100 acres, whereas the average automobile worker turns out perhaps 10 cars a year, worth 10,000 bushels of wheat or more? Yet the only way in which products can be compared is through the exchange values attached to them in the market. Any attempt to evaluate productivity on a national scale must therefore involve the weighting of goods produced according to the prices at which they were sold. The most that can be done to place production figures on a real basis is to attempt to eliminate variation in prices; and thus determine the extent to which the total volume of production of all goods in the economy, weighted according to their price relationships at some specific point of time, has grown over a period of years. In the discussion that follows, therefore, the gross national product in 1935–9 dollars is used as output. It would perhaps be better to use national income, but this is difficult to deflate in view of the inclusion of indirect taxes in price indices.

Supposed Land Subsidence in the South of England

Relative vertical movement of land and sea has played a great part in geo? logical evolution. The process is however so slow that its detection by measurement rather than by inference is difficult. Since there are places where such movements have demonstrably gone on during the present and recent centuries and since those places are not very distant from our own shores, it is natural to inquire whether Great Britain shares in the movements. The known elevation of northern Scandinavia at a mean rate of about i metre per century and the depression of the Netherlands coast at rather less than a quarter of that mean rate might have been accompanied by elevation in the extreme north of Scotland and depression in the neighbourhood of the English Channel. The available archaeological evidence is very interesting and significant in this connection. It is quite clear that the land surface in the Thames valley has sunk about 15 feet with reference to tidal levels since the Roman occupation.1 There is to-day a densely populated area of some square miles in south London which is from 5 to 6 feet below ordinary high-water mark. Further, on both sides of the western English Channel there is archaeological evidence of subsidence which may belong to the historical period. The evidence of such things as buried forests is also conclusive, but scarcely concerns the present discussion because it is related to too remote an epoch. An aggregate movement of subsidence amounting to 40 feet in the last ten thousand years would be quite consistent with a contrary movement at the present day. The only method of detecting movement in progress is to keep a careful record of sea-level by means of one or more autographic and continuously acting tide gauges. This was one of the purposes for which the Ordnance Survey erected three tide gauges at Dunbar, Newlyn, and Felixstowe in the years 1913, T9T5> and 1917 respectively. Another purpose was the provision of a datum level surface for the Second Geodetic Levelling of England and Wales, 1912-21.2 The level of the sea at each tidal station is determined in relation to a so-called contact point on the framework carrying the gauge, and the height of the contact point is controlled by frequent levellings to the observatory bench mark, perhaps half a mile away. The latter itself is con? trolled by an annual relevelling to the nearest fundamental bench mark, which may be some miles away. These very necessary precautions ensure the