Population Density Distribution Research Articles

Effects of chloroquine and Nifedipine on the phospholipid content and enzyme activity in the subcellular fraction of ischemic rat liver.

Using a liver ischemia model, we examined the change that occurs in the phospholipids and marker enzyme activities of subcellular membrane-structures, as well as in the ultrastructure of the cells during ischemia. The left and median lobes of liver were made ischemic by occlusion of branches of the hepatic artery and portal vein; after 3 h the liver was excised, homogenized and fractionated. Of total 79 rats, 29 rats received via gastric tube 100 mg chloroquine/kg for 7 days prior to ischemia, or an intraperitoneal injection of Nifedipine (50 μg/kg; n=23). In some of these rats (n=28), the occlusion was removed, and the analyses were carried out 24 h later. The following findings were obtained; 1) Ischemia of 3-h duration reduced the phospholipid content (per mg protein) of the lysosomal, microsomal and postnuclear fractions, but not that of the mitochondrial fraction. 2) Pretreatment with chloroquine prevented to a large extent the ischemia-induced reduction of phospholipids. Some phospholipids in the heavier-density lysosomes decreased, and some of those in the lighter-density lysosomes increased by ischemia, suggesting that ischemia changed the density distribution of lysosomal population. 3) Nifedipine also reduced the ischemia-induced phospholipid change but to a lesser extent. 4) Electron microscopic observation indicated that the number of lamellar bodies appeared in the chloroquine-treated rat liver was decreased during 3-h ischemia; the ultrastructural alterations of ischemia appeared not to be greatly influenced by the chloroquine pretreatment. 5) The activity of mitochondrial cytochrome c oxidase and that of lysosomal acid phosphatase were decreased by ischemia; the chloroquine treatment prevented these decreases, but Nifedipine treatment did not. The depressed activity of microsomal NADPH cytochrome c reductase was ameliorated by chloroquine. These results indicate that enzyme activities change independently of a change in phospholipid content in the subcellular organelles during ischemia. 6) The three enzyme activities remained depressed in the liver of the non-treated rat 24 h after the resumption of blood flow. At this time the mitochondrial phospholipid content was significantly decreased. These changes were largely prevented by pretreatment with cloroquine. 7) These results suggest that the Ca2+-activation of subcellular phospholipases or the action of lysosomal hydrolases cannot be the sole mechanism leading to the development of ischemic cell injury.

Convolution of fabric data to determine probability distribution

To investigate the higher order, multimodal characteristics of fabric data populations, five filter operators are constructed on the surface of the reference hemisphere for convolution with fabric data. These operators include spherical unit disk, triangle, sinc, sinc 2 and Gaussian functions. To illustrate filter performance, two fabric data sets, taken from the lower Schoonover sequence of the Northern Independence Mountains, Nevada, are convolved with the filters. The results show that the spherical unit disk, triangle and sinc operators are especially useful for identifying characteristics of the population density distribution and related probability contours for unimodal data sets. The Gaussian and sinc 2 operators, however, provide increased resolution of the higher frequency components for multimodal fabric data sets, along with relative statistical probability contours from which inferences on the probability distribution of the population can be made. In general, the convolution process is a very effective tool for analyzing the multimodal behaviour of fabric data, because of the ease and the flexibility with which filter operators may be designed.

Population characteristics of the intertidal green sea anemone, Anthopleura xanthogrammica, on the Oregon coast

Field population censuses using a photographic quadrat method were used to describe the density and size structure of intertidal populations of the green sea anemone, Anthopleura xanthogrammica, on different types of rocky intertidal habitats on the Oregon coast. Anemone populations in marked plots were monitored for individual motility, growth, mortality and recruitment. Experiments were performed to evaluate anemone population responses to simulated harvesting. Rocky intertidal locations with dense populations of the green anemone are not abundant along the Oregon coast. No detectable fluctuations in anemone population density or size-frequency distribution were found during the 2-year study. Adult anemones showed little movement in either disturbed or undisturbed populations. No natural mortality or recruitment was found in study plots at any Oregon coastal location between July 1977 and May 1979. Removal of adult anemones from rock surfaces did not promote recruitment from the plankton onto the newly available surface, nor did individuals adjacent to depopulated plots rapidly immigrate into the cleared areas. Individual growth is inferred to be very slow in intertidal populations. Field studies indicate that A. xanthogrammica is a long-lived, slow growing species with limited, low or erratic recruitment and highly stable intertidal adult populations. This study indicates that harvest of A. xanthogrammica will probably not be possible on a continuing basis.

Modelling urban population density in a multi-centered city

Modelling the geographic distribution of urban population densities has been attempted in several ways. Recently a controversy emerged in the Journal of Urban Economics regarding whether or not calibrations of these models render unbiased parameter estimates. Three sources of bias were dealt with in these discussions, namely (1) model specification error, (2) the estimation procedure employed, and (3) the definition of areal unit observation size. Additional sources of bias overlooked in this controversy include the presence of multiple centers in a city, and the existence of externalities. This paper explores these additional sources, from both a conceptual and an empirical point of view.

Methodological approaches on medical care planning from the viewpoint of geographical allocation model: A case study on South Tama district

The authors studied the changing pattern of geographical distribution of medical facilities and population density in a suburban district of Tokyo. The data sources are the population census in Japan of 1965, 1970 and 1975, and a survey of medical institutions by the TAMA Medical Association in 1978. The district was divided into 215 unit cells by the Standard Mesh System (Japan Grid Reference System). We used the quantitative geographical method in order to analyse the development of medical facilities from the viewpoint of planning theory. According to the results, the tendency towards increase in number and sorts of medical facilities had been close to the development of the population density in the district as in the theoretical pattern of market development. However, details of the process and the tendency are slightly different from it. The authors also discuss the present situation concerning planning of medical care delivery system in Japan.

Anti-AMP antibody precipitation of multiply adenylylated forms of glutamine synthetase from Escherichia coli: a model relating both concentration and density of antigenic sites with the antibody-antigen interaction.

Sheep antibodies directed against an AMP-bovine serum albumin conjugate exhibit highly specific binding toward AMP. These antibodies bind to the AMP moiety of adenylylated glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] from Escherichia coli and to no other antigenic determinant on the protein. E coli glutamine synthetase can exist in variously modified (isomeric) forms that differ with respect to the number (0-12) and the distribution of identically adenylylated subunits [Ciardi, J. E., Cimino, F. & Stadtman, E. R. (1973) biochemistry 12, 4321-4330]. Using this enzyme, together with the AMP-specific antibodies, we have investigated the effects of the total concentration, population density, and topographical distribution of multiple identical antigenic determinants on the antigen-antibody interaction. Stopped flow fluorescence measurements show that the rate and extent of initial binding of the antibodies to the antigen are a function of the total concentration of AMP groups and are independent of the number of AMP groups der dodecamer. However, the rate of lattice formation increases with increasing epitope density, and the maximal amount of glutamine synthetase precipitated is directly proportional to the average number of adenylylated subunits per dodecamer. The data suggest that partially adenylylated enzyme preparations are composed of subpopulations of glutamine synthetase molecules that differ in their tendency to form precipitable aggregates, due presumably to differences in the topographical distribution of antigenic determinants on the surface of the enzyme. The enzyme species that form soluble immune complexes do so possibly due to intramolecular crosslinkage of the bivalent antibodies with adenylylated subunits to the exclusion of intermolecular crosslinkage.

Diel vertical migration by males, females, copepodids and nauplii in a limnetic population of diaptomus (Copepoda)

Diel vertical migration (DVM) by the sexes and life history stages of the copepod Diaptomus novamexicanus (Herrick) was investigated during two summers in a subalpine lake (Castle Lake, California, USA). Migratory behavior was quantified repeatedly by 1300 and 21–2200 hr sampling in the epilimnion. Population density and vertical distribution were estimated routinely at 1300 hr and at 2200 hr on selected dates. Males had greater night to day biomass differentials and ratios than females. The sexes showed comparable DVM participation (% of total biomass migrating) and amplitudes of migration (distance of ascent). Copepodids displayed higher participation, night/day ratios and amplitudes than younger copepods, but adult participation differed only from that of nauplii. Active participation in high amplitude ascents thus increased with age and was greatest in adult males. Analysis suggests that such relative behaviors probably occur in most limnetic Diaptomus, and that the magnitude of ascent into the epilimnion is associated with daytime vertical distribution.

Sorghum-pigeonpea intercropping and the effects of plant population density

SummaryThe use of growth resources is examined in an intercropping combination of early sorghum (82 days) and later-maturing pigeonpea (173 days) in a row arrangement of 2 sorghum: 1 pigeonpea.Prior to sorghum harvest, light interception by the intercrop combination was almost as high as sole sorghum. After sorghum harvest, light interception by the remaining pigeonpea was very poor and it is suggested that pigeonpea yield could be increased with higher plant population density and better plant distribution. Soil water measurements indicated that this would increase the amount of water being transpired through the crop but would not increase the total evapotranspiration demand. Higher nutrient concentrations in the intercrop pigeonpea compared with sole pigeonpea during this post-sorghum period suggested that yield of intercrop pigeonpea was not limited by nutrient stress, though the total uptake of nutrients by both crops was much greater from intercropping than sole cropping.

A New Model for the Population Density Distribution in an Isolated City

Geographical AnalysisVolume 12, Issue 3 p. 223-235 Free Access A New Model for the Population Density Distribution in an Isolated City Hideaki Ishikawa, Hideaki Ishikawa The author wishes to express sincere thanks to Professor T. Tokita for enjoyable discussions and encouragement. The author also thanks Mr. K. Arai and Mr. Y. Sugiura. Hideaki Ishikawa is a graduate student in physics, Tokyo Metropolitan University.Search for more papers by this author Hideaki Ishikawa, Hideaki Ishikawa The author wishes to express sincere thanks to Professor T. Tokita for enjoyable discussions and encouragement. The author also thanks Mr. K. Arai and Mr. Y. Sugiura. Hideaki Ishikawa is a graduate student in physics, Tokyo Metropolitan University.Search for more papers by this author First published: July 1980 https://doi.org/10.1111/j.1538-4632.1980.tb00032.xCitations: 10 The author wishes to express sincere thanks to Professor T. Tokita for enjoyable discussions and encouragement. The author also thanks Mr. K. Arai and Mr. Y. Sugiura. Hideaki Ishikawa is a graduate student in physics, Tokyo Metropolitan University. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume12, Issue3July 1980Pages 223-235 ReferencesRelatedInformation

Development of a Model for Use in Maize Replant Decisions1

AbstractReduced stands after planting may force maize (Zea mays L.) producers to consider the feasibility of replanting. The objective of this research was to develop guidelines for replanting decisions based on planting date, hybrid maturity class, population density, and plant distribution. Maize was planted at central and northern Illinois locations in 3 successive years. In each experiment adapted and early season hybrids were planted at three dates ranging from late April through early June. Plots were thinned to final densities of 30,890; 41,180; 51,480; and 61,780 plants/ha. The three lower densities were distributed uniformly within the row, with small gaps ranging from 0.42 to 0.85 m long, and with large gaps 1.5 m long.Adapted hybrids tended to yield more than early season hybrids when planted before 20 May, but the overall effects of hybrid maturity class were minor. Regression analysis indicated that the optimum planting date was near 6 May, and planting either 2 weeks before or after 6 May reduced yields by less than 5%. However, a rapid decrease in yield due to planting date occurred when planting was delayed past 20 May. Averaged across environments, the interaction of planting date with density and plant distribution was not significant. Before mid May the major factors to consider in replant situations are density and plant distribution within the row. After mid May, calendar date increases in importance. A model for uniformly spaced plants is presented that predicts yield on the basis of planting date and population density. Compared to uniform spacing within the row, small gaps reduced yield by an average of 1.9% while large gaps reduced yield by 5.4%.

A collisional-radiative model for helium and its application to a discharge plasma

For the collisional-radiative model applied to helium, two alternative formulations are presented in which non-linear process such as ionization due to metastable-metastable collisions may be included. The atomic data, including dielectronic,recombination, employed in the calculations are summarized. The collisional-radiative calculation is applied to a positive-column plasma for which both the nonlinear processes and radiation trapping are taken into account. The calculated population densities of excited levels for a low-pressure and low-current discharge plasma show good agreement with a measurement made using the hook method. The population density distribution among excited levels is interpreted in terms of excitation-ionization mechanisms in the plasma. This leads to a grouping of the excited levels into two phases for the discharge plasma considered: the corona phase applies to the lower-lying levels and the quasi-saturation phase to the higher-lying levels. The importance of the ladder-like excitation-ionization mechanism is noted for this class of plasmas.

Population Growth and Abandonment of Swamplands. A New Guinea Highlands Example

This paper is aimed at providing additional data about the controversy surrounding the extent of the impact of sweet potato introduction to the New Guinea Highlands some 300 years ago. First, the demographic question is discussed through data available on a single tribe (Kawelka) and speculations about the implications for Prehistory are made. Because this tribe has been recently split into two distinct settlements, only tentative statements concerning general responses to population and land pressures are made. The second section of the paper, based on data provided by early Patrol Reports and personal investigations, infers the geographical distribution of tribes, their economy and population densities in the swampy valleys of the Highlands just prior to the sweet potato introduction. Disease epidemic(s) are seen as the reasons of the abandonment of these swamps prior to the European penetration in those areas (1933).

ANALYZING THE IMPACT OF LAND USE ON SEWER SERVICE AREA PLANNING1

ABSTRACT: The density and distribution of land uses has important consequences for the planning of sewerage systems and for the costs of these systems. This paper examines these consequences using a simplified service area model. The model determines the area to be served by a central waste treatment plant, where alternative on‐lot disposal systems are also available. The model is applied to various urban area configurations, which are summarized by their total populations and by their population density distributions. Both minimum regional cost and minimum local cost service area configurations are determined. In addition, the sensitivity of the model to the parameters of the cost and population density functions is assessed. It is found that the model is most sensitive to the parameters of the collection cost function.

National roadway traffic noise exposure model

This model is one element of a continuing effort to quantify the exposure of the U. S. population to noise generated by motor vehicle traffic. This model simulates the noise generated by motor vehicles operating on the national roadway network. To calculate noise impact estimates both deterministic and statistical techniques are used, incorporating roadway configurations, population density distributions, and vehicle classes. A large data base is utilized to characterize the national roadway network, the traffic conditions on all roadways, and the distribution of the population surrounding the roadway network. Population growth, changes in roadway characteristics, and changes in traffic conditions that vary from year to year can be accounted for. Path and receiver control measures can also be incorporated into the model for decision making purposes. This paper discusses the model, illustrating its flexibility as a decision making tool in assessing national community noise exposure and changes due to various control measures as a function of time.

The Expansion of Urban Area and the Spatial Distribution of Urban Population Density in Seoul City

The purpose of this paper is to clarify the characteristics of primacy and the expansion of urban area in Seoul city. In addition to these, this study aims to bring out the spatial distribution of urban population density in Seoul city by using Clark's and Newling's models and also trend surface analysis. The main results are summarized as follows:1. Seoul city had emerged as a primate city since 15th century when it became the residential area of elite during Lee dynasty. Further, a few historico-economic factors have greatly increased the primacy of this city in the present century. The main factors are1) The colonial policy of Japan during annexation period.2) The immigration and migration after Japanese withdrawal and Korean war respectively and3) The rapid economic development during recent years.2. The structure of Seoul city, with reference to the extent and pattern of built up area, and the historical and economic structure within it, shows Dickinson's zonal arrangement theory (Fig. 3). The zone may be sub-deviled as follows:1) Central zone: The zone before the expansion that is, 1910 and the part of adjacent zone.Population density is 10, 000persons/km2-20, 000persons/km2 in this zone.2) Middle zone: The zone between 1936 and 1962. Population density is around 10, 000persons/km2 to 60, 000persons/km2 in middle zone.3) Outer zone: The zone after 1963. This zone shows a population density of 5, 000persons/km2-10, 000persons/km2.3. Clark's linear exponential model and Newling's quadratic exponential model illustrating the density profile of whole urban area and four sectorial components are shown in table 3 and Figures 6 and 8. Each parameter shows that the city has spread out further towards the North-East and South-West than towards the South-East and North-West. It is because each sector is different from its profile which is due to the time of formation in the built-up areas, the density of residence and residential quality, transportation accessibility and the pattern of land use. The distribution of residuals from the Clark's model indicates the negative value in the city center and in the areas containing non-residentials such as mountainous terrain, military areas, old palace and schools. On the other hand, the densely populated residential area nearby the city center shows the active value (Fig. 7).4. The spatial quadratic trend surface forms nearly the hyperbolar indicating the saddle point of the city center. The isopleth of the trend surface shows the decline of population density with distance from the city hall to the South and North and the increase to the East and West (Fig. 9). It may be regarded that the profile of the density crater is transformed into hyperbolar because of the mountainous terrain in the North and military areas in the South.5. Berry pointed out that non-western cities continued increases in D0 (overcrowding) and relative constance of b (urban expansion without suburbanization) in the western sense, but his assumption does not fit in the case of Seoul city. The result of each components, residual maps and the trend surface illustrates well the density crater of the city center. Moreover, improved transportation systems and a great demand for peripheral lower density-areas stimulated the urban sprawl as are shown in the case of the western cities.

The entropy paradox and the distribution of urban population

This paper presents an empirical application of an information theoretic approach to spatial hypothesis testing. Following the lead of Batty [1] this study employs the concept of expected information to test hypotheses concerning the distribution of urban population and population density in San Antonio for the years 1960 and 1970. Cast for the first time in a longitudinal context, major concerns of this work are the relative advantages, both theoretical and methodological, of certain entropy measures. Specifically, comparisons are made between the Shannon and the Kullback formulations. In this context of comparison, problems closely linked to what has been called the “entropy paradox” are identified and explained, suggesting important qualitative differences between these two measures.

Effect of annual and perennial cropping regimes in microplots on the population density and vertical distribution of Xiphinema diversicaudatum and on soil porosity

SUMMARYLong‐term trends in populations of Xiphinema diversicaudatum were measured in two microplot experiments in which annual and perennial crops of seven plant families were grown in monoculture.Numbers of X. diversicaudatum increased under perennial ryegrass, raspberry and strawberry but decreased under hop, spring barley, potato, sugar beet, cabbage, winter wheat and winter beans; these effects probably reflected differences in the inherent host status of the crops. There were fewer X. diversicaudatum at 40–60 cm below annual crops than below perennial crops, and there were differences between perennial crops in nematode vertical distribution.Soil pore space did not limit nematode population density; total pore space was uniformly large under all crops and there was no detectable instability to water slaking. Under ryegrass a greater proportion of soil volume was occupied by pores too small to accommodate X. diversicaudatum, but since ryegrass supported the second largest nematode population, it seems unlikely that this was seriously limiting.

The Social Regulation of Population Density and Age-Sex Distribution in the Toque Monkey

The Social Regulation of Population Density and Age-Sex Distribution in the Toque Monkey

A Dynamic Feedback Approach to Modelling Spatial Population Density

This paper presents an approach to modelling population density as a function of space and time, both of which are treated over a continuous domain. An equilibrium (or alternatively, an optimal) distribution of urban population density is specified exogenously. The rate of change of the actual population density is then considered to be a function of the deviations between the actual and the equilibrium (or optimal) density distributions, over time. This adjustment process is interpreted as being realized by internal migration, immigration/emigration, and/or natural growth. A formal specification of the models results in integral—differential equations. A solution procedure that uses double Laplace transforms and partial Laplace transforms with respect to space and time is outlined. Properties relating to the limiting distributions are discussed. An example that makes use of exponential functions is presented; and procedures for computing explicit, and possibly heuristic, solutions are noted.

A Comparison of Fabric Diagrams in Terms of Reproducibility, Accuracy, and Economy

The methods of Schmidt and Mellis, as well as a new technique, which determines the fabric diagram on the surface of a reference sphere and subsequently projects it onto the associated meridial plane, are examined and evaluated. A description of each method along with detailed considerations necessary for the computerization of these respective techniques is presented. Comparisons between the various fabric diagrams produced and plotted by the computer show that the reproducibility of the equal-area projection of the new spherical method is quite good, whereas the Schmidt and Mellis techniques are directionally affected. In general, the equal-area projection of the spherical diagram maintains a considerable advantage in terms of the accuracy and efficiency with which population density distributions may be represented. It is found that a spherical grid spacing of 3 degrees, representing 30 × 120-grid points, gives a sufficiently accurate fabric diagram commensurate with the exigencies of computer accessibility and errors of fabric measurement. A highly satisfactory comparison is presented to aid the geologist or geotechnical engineer in choosing the most accurate and efficient computerized mode of fabric data representation.