Population Density Distribution Research Articles

Formation of excited states of atoms and ions in laser plasma from CuInS2

Emission spectra and the energy distribution of the excited-state population density of atoms and ions in erosion laser plasma from CuInS2 with various crystal-structure orderings are analyzed. It is shown that increased ordering of the target crystal structure causes the excited-state energies of indium atoms generated in the laser erosion plume to increase and that sulfur atoms always emit only in transitions from highly excited states. The ratio of relative ion concentrations in the laser plasma plume is Cu+/In+/S+ = 0.3/0.08/2, which corresponds neither to the atomic ratio of Cu/In/S (1/1/2) in the target nor to the ratio of ionization energies. The results are explained by recombination processes for ions and by the atomization specifics of the CuInS2 target exposed to long-wavelength radiation. The atomization consists essentially of dissociative processes expressed by CuInS2 → CuInS + S and CuInS2 → Cu + InS + S. The electron temperature of polycrystal (single-crystal) plasma at a distance of 1 mm from the target is 0.3 eV (0.4 eV) for atoms and 1.3 eV (2.7 eV) for ions and varies negligibly for plasma up to a distance of 7 mm from the target.

Patterning in Urban Population Densities: A Spatiotemporal Model Compared with Toronto 1971–2001

We build on the literature on population-density distributions, but translate the consensus cross-sectional progression into a three-dimensional and six-stage geographic information system (GIS) based ‘volcano’ model. Visual comparison and descriptive statistics show Toronto's recent density patterns to be very similar to those suggested by the model: the central density cluster has reversed its decline, while peripheral clusters have developed at increasing distances from downtown. Local autocorrelation (LISA) allowed areas of significant clustering and diversity to be mapped, and strong conformity was found between the model and Toronto's empirical patterns. Overall, density levels throughout the metropolitan area are homogenizing and randomizing, even while inner-city redensification and peripheral densification proceed.

World Poverty, Environmental Vulnerability and Population at Risk for Natural Hazards

Please click here to download the map associated with this article. The objective of the accompanying map is to show the relation between world poverty, environmental vulnerability and population at risk for natural hazards. Sub-national infant mortality rates are used as proxy for poverty and mapped as a bivariate choropleth map together with national levels of environmental vulnerability. Past density and distribution of natural hazards were mapped on to a textonequarter degree grid and presented as an inset map. An inset map with global population densities is also provided. All maps are in Lambert cylindrical equal-area projection. The main map scale is 1:100 000 000. According to the result from the bivariate mapping of poverty and environmental vulnerability, the world can be stratified into three groups. 1) Regions with low poverty rates and relatively high degree of environmental vulnerability (e.g. Scandinavia, North America). 2) Regions with high levels of poverty and a relatively low degree of environmental vulnerability (e.g. parts of East-Africa, parts of Russia). 3) Regions with high poverty rates and high degrees of environmental vulnerability levels (e.g. middle parts of Asia). When this information is combined with that of population density and natural hazard density and distribution it is clear that those belonging to group three are very vulnerable with usually high population densities and a location prone to natural hazards. This type of small scale mapping is a good way of exploring relations between variables, observing geographical patterns and bringing forward new hypotheses for future research directions, and should be viewed as a complement to large scale mapping and field inventories.

Size-dependent growth kinetics of vitamin C crystals in water solutions of L(+)-ascorbic acid with the addition of methanol and ethanol

Size-dependent growth kinetics of vitamin C crystals in water solutions of L(+)-ascorbic acid with the addition of methanol and ethanol Growth kinetics of vitamin C crystals during the batch mass crystallization process in L(+)-ascorbic acid - methanol - ethanol - water system was determined. The linear growth rate values were estimated on the basis of the product crystal size distributions. The kinetic model of the continuous process in a MSMPR crystallizer was adopted for the batch mode description according to Nyvlt's conception, taking the sizedependent growth (SDG) rate effects into consideration. The kinetic parameter values were determined with a Rojkowski hyperbolic SDG model. A good compatibility between the experimental product crystal population density distributions and the SDG model predictions was observed. The interpretation of the kinetic data was presented and discussed.

Spatial distribution regularity and influence factors of population density in the LRGR

Combining GIS measures and statistic methods, this paper selects the physiographic factors and climatic factors to study the influencing strength and its functional forms of all factors on population density in the LRGR. In addition, this paper simulates the status of population density distribution in the LRGR with the factors influencing the population density distribution. The findings indicate the following circumstances: (1) All natural factors have influence on the spatial pattern of population density in the LRGR, but the influencing extent and forms are quite different. Physiographic factors and traffic network density have great influence on population density, while such factors as temperature and precipitation have little influence on population distribution. The relationship between the population density and the altitude and traffic network density assumes the negative and positive linear correlation trends, while the influence of water system density and slope appears to be the exponential function and logarithmic function separately. (2) The population is scattered throughout LRGR and takes on such features as integral scattering and local concentration because of the influence of natural conditions. Thus, a high population density belt has been formed in the middle of LRGR, and a high population density patch comes into being in the south of LRGR. (3) There is a good linear regression relationship between population density and human activity index (HAI) in the LRGR, which reflects that population density can present the artificial disturbance on natural ecosystem in the LRGR. (4) The increase of population density leads to the decrease of NDVI index.

Reaction‐Crystallization of Struvite in a Continuous Liquid Jet‐Pump DTM MSMPR Crystallizer with Upward Circulation of Suspension in a Mixing Chamber – an SDG Kinetic Approach

AbstractThe experimental results concerning kinetic aspects of struvite precipitation in a continuous DTM‐type crystallizer with internal circulation of suspension forced by a liquid jet‐pump are presented and discussed. Nucleation and crystal growth rates of struvite during reaction‐crystallization processes in diluted water solutions of magnesium, ammonium, and phosphate ions were identified. Kinetic parameters were calculated on the basis of population density distributions adopting a simplified model of the mass crystallization process in a MSMPR crystallizer taking under consideration size‐dependent growth (SDG) mechanism. The Rojkowski hyperbolic SDG model has proved to be the equation best statistically fitted to our own data set.

Measuring population pressure on the landscape: comparative GIS studies in China, India, and the United States

Measures of the effects of population pressure on the landscape using traditional methods for classifying urban territory are inadequate. The crude scale at which population densities are calculated and dependence on country-specific administration divisions hinder their ability to address such questions as the environmental impacts of cities and suburbs and make cross-national comparisons particularly difficult. This paper examines comparative urbanization measures among three case studies: the Pearl River Delta in Guangdong Province of China, the Indian state of Kerala, and the southern part of Florida in the United States. It proposes a measure based on the distribution of local population densities, taking advantage of the detailed data on small area populations and land area available in modern censuses and model-derived population databases such as LandScan, and the increasing potential of spatial analysis using geographic information systems (GIS). Examined with a similar set of thresholds, the resulting density distributions offer the potential to show better the ecological effects of population than do traditional measures.

Geographic Box Plots

Traditional box plots, described by Tukey in 1977, can be biased representations of geographic or spatial variables, since they do not take into account the areas associated with the elements of geographic variables. To help solve this problem, we propose and evaluate a spatially (areally) weighted box plot, a "geographic box plot," that can be used to describe a wide variety of geographic variables. Much of our discussion of box plots also applies to "traditional" and "geographic" histograms and percentile plots. Traditional and geographic box plots of one hypothetical and two real-world geographic variables are constructed and compared to illustrate our points, as well as to illustrate the often marked differences between traditional and geographic box plots of the same geographic variables. The real-world geographic variables considered here are human population density (in the year 2000) within the contiguous 48 United States and five-year-average (January 2001-December 2005) air temperature over the Arctic land surface. Our traditional box plot of population density over represented the small, high-density states, whereas our corresponding geographic box plot correctly depicted the geographic distribution of population density. A geographic box plot correctly accounted for the reduction in spherical grid-node areas with latitude over the Arctic land surface, whereas a traditional box plot of the spherical grid-node values did not. Our hope is that geographers and other scientists will make refinements to and find many more applications for our geographic box plots.

Vertical distribution, population density, and natural egg parasitism of cotton leafworm on cotton under IPM

Alabama argillacea is one of the most important pests of cotton crops in Brazil, and therefore it is necessary to research its behavior and natural biological control in areas under IPM conditions to improve the management of its population. In the pursuit of this objective, experiments were carried out on cotton crops in Dourados, Mato Grosso do Sul, in the 1997-1998 growing season. With the object of determining the population density and vertical distribution of eggs, larvae, and pupae, the total number of eggs, small, medium and large sized larvae and pupae found on the upper, middle, and lower sections of the plants were weekly recorded. This was conducted in an area where pest management was done according to IPM techniques and tactics. In the same area, eggs of this species were also gathered to determine the proportion of parasitism. The pest lays the majority of eggs on the upper part of the plants where the majority of midand large-sized larvae were also found. Small larvae were generally found on both middle and lower parts of the plants. A growing percentage of parasitism by Trichogramma pretiosum was found from the beginning through the end of the crop season, reaching almost 100% parasitized eggs by the end of plant development. The average number of eggs found per plant was high during almost the whole crop cycle, reaching about 30 eggs per plant by the end of the cycle. The total number of small caterpillars was high and constant during the whole evaluation period, while medium and large ones were more abundant in the final phase of the crop cycle. The total caterpillar population reached peaks of around four caterpillars per plant.

Occurrence of phthalate diesters in rivers of the Paris district (France)

AbstractThe occurrence and fate of six phthalate esters were investigated in the River Seine and two tributaries in the Paris area, at six sites from upstream to downstream, throughout different seasons, with special attention given to a flood episode. At all sites, except the River Marne, whatever the period, diethylhexyl phthalate (DEHP) displayed the highest concentration (0·323–0·779 µg l−1 as mean values), followed by di‐n‐butyl phthalate (DnBP; 0·211–0·526 µg l−1 as mean values), which is consistent with the production pattern. High phthalate concentrations appeared to be related to population density and industrial distribution. The strongest values were located downstream from wastewater treatment plant effluent inputs. Seasonal variations were closely related to river flow and air and water temperature. The annual evolution of phthalates was linked to the hydrological conditions. During the flood episode at Paris, the DEHP concentration displayed a sharp increase (260 to 1123 ng l−1) occurring 9 days before the flood peak. The simultaneous fluctuations of NH4, typical of domestic origin, and of DEHP suggests a similar origin from combined sewer overflows for both compounds. Other elevated values corresponded to the highest precipitation amounts, and demonstrated the contribution of non‐point‐source runoff and wastewater overflow to DEHP inputs. The DEHP concentration relationship with river flow displayed a clockwise hysteresis loop, corresponding to a ‘first‐flush’ effect in which the finite supplies are swept along in the early stage of the flood. Annual fluxes for 2004 at Paris were 2257 kg of DEHP and 1613 kg of DnBP. The flood period seemed to have a minor impact on annual phthalate transport (29·5% and 41% of the total for DEHP and for DnBP, respectively), which is contrary to annual suspended solids transport (69%). Copyright © 2007 John Wiley & Sons, Ltd.

Three-dimensional analysis of microwave generated plasmas with extended planar laser-induced fluorescence

We present the development and application of a diagnostic system for the analysis of microwave generated low-pressure plasmas, which might also be used for the investigation of the edge regions in magnetically confined fusion plasmas. Our method uses planar laser-induced fluorescence, which is produced by excitation of neutral metastable atoms through a short, intense, pulsed laser. The beam expansion optics consist of an uncommon setup of four lenses. By controlled shifting of an element of the optics sideways, the location of the laser sheet in the plasma is scanned perpendicular to the excitation plane. Together with a spectrometer observing different observation volumes along the beam path, we are able to map absolute three-dimensional (3D) population density distributions of the metastable ((2)P(12) (o)) 3s[12](0) (o) state of Ne I in an electron cyclotron resonance heating (ECRH) plasma. This optical tomography system was used to study the influence of the microwave power and mode on the spatial structure of the plasma. The results show that the population density of the neutral neon in this metastable state is found to be in the range of 10(16) m(-3), and that its spatial distribution is associated with the 3D structure of the magnetic field. We also report that the spatial distribution strongly varies with the mode structure, which depends on the microwave power.

Nucleation and Crystal Growth Rates of Struvite in DTM Type Crystallizer with a Jet-Pump of Descending Suspension Flow in a Mixing Chamber

The kinetic data concerning reaction-crystallization of struvite from diluted water solutions of Mg2+, NH4+ and PO43- ions in a continuous DTM-type liquid jet-pump crystallizer with internal circulation of suspension are presented and discussed. The measurements were performed with the assumption of minimal value of unit power of a jet-pump’s feeding stream, providing thus a minimal level of internal circulation intensity. Nucleation and linear growth rates of struvite crystals were calculated on the basis of population density distributions of product particles. A mathematically convenient kinetic model for MSMPR crystallizer, making allowance for a size-dependent growth (SDG) phenomenon, was adopted for description of a complex process of precipitation integrated with crystals growth. It was concluded, that in the concentration range of magnesium ions in a feeding solution [Mg2+]RM = 0.1-2.0 mass % and, in stoichiometric proportions, phosphate ions [PO43-]RM = 0.39-7.81 mass % as well as the ammonium ions [NH4+]RM = 0.074-1.48 mass %, the Rojkowski hyperbolic SDG kinetic model proved to be an equation the best statistically fitted to the own experimental data.

Population Structure and Density of Leopard Tortoises (Geochelone Pardalis) on Farmland in the Nama-karoo

The Leopard Tortoise (Geochelone pardalis) is the largest of the southern African species and has a wide distribution encompassing a variety of habitats. There is a paucity of ecological information about Leopard Tortoises in these habitats. The goal of this study was to determine the population density, biomass, sex and age distributions, and morphometrics of Leopard Tortoises on farmland in the semi-arid Nama-Karoo. Because previous studies have found that body size distributions vary between mesic and xeric habitats, we expected that these Leopard Tortoises would show an increased body size compared to those from more mesic areas. In addition, we expected lower densities of Leopard Tortoises compared to more mesic areas. In total, 92 tortoises were caught with a male to female sex ratio of 1:1.3 that was not significantly different from unity. Adult females were significantly larger than males with respect to all morphometric measurements. Leopard Tortoises (excluding juveniles) were larger than those from more mesic areas. A population estimate of 57.6 ± 4.0 tortoises in a 5500 ha area was obtained using a mark-recapture sampling method and radio-telemetry. Density of tortoises was extremely low at 0.017 tortoises ha−1, with a biomass of 0.002 kg ha−1. Population density and biomass were lower compared with Leopard Tortoise populations in more mesic areas. This has implications for the understanding of fitness parameters and conservation of this species in semiarid areas.

A tale of three seas: consistency of natural history traits in a Caribbean–Atlantic barnacle introduced to Hawaii

Predictive models in invasion biology rely on knowledge of the life history and ecolog- ical role of invading species. However, species may change in key traits as they invade a new region, making prediction difficult. For marine invertebrate invaders there have been too few comparative studies to determine whether change in key traits is the exception or the rule. Here we examined populations of the intertidal barnacle Chthamalus proteus in three locations in its native range in the Caribbean and Atlantic, and in the Hawaiian Islands, where it has recently invaded, as a model system for such comparative studies. We measured body size, fecundity, population density and vertical distribution, compared hab- itat use and investigated aspects of the barnacle's ecological role in Curacao, Panama and Brazil and the main Hawaiian Islands. In terms of these measures, the barnacle has undergone little change in its invasion of Hawaii. Thus, if this barnacle had been studied in its native range, predictions about its spread in Hawaii could have been made. As little was known about this barnacle in either its native range or Hawaii, we also carried out studies of its larval life history, fecundity, growth, and mortality. Based on this work, we predict that this barnacle will continue to spread, aided by vessel traffic, throughout the Hawaiian Islands and elsewhere in the Pacific.

Air Quality Modelling Application to Evaluate Effects of PM Air Concentrations on Urban Population Exposure.

P-015 Abstract: Air pollution is a major environmental health problem causing approximately three million deaths per year in the world, as result of exposure to particulate matter (PM). For population exposure assessment, a combination of the spatial distribution of both air quality and population density is required. Numerical models are useful tools for the mapping of air pollutants, once the monitoring networks are able to assess the air quality in the single stations of the monitoring network, and not the whole area of interest. Dispersion and photochemical models have been applied, at different scales, to evaluate air pollution due to particulate matter concentrations and its effects on human exposure and health. In Portugal, especially in urban agglomerations, like Porto and Lisboa, particulate matter air concentrations are exceeding the correspondent limit value imposed by the EC Air Quality Framework Directive, with unavoidable effects on populations' health. In fact, during the past four years, most of the air quality monitoring stations of Porto region has registered a number of PM10 daily averaged values above the limit threshold, which was higher than the allowed 35 exceedings per year. Aiming to characterize and evaluate the likely human exposure to air pollution and its effects on the health of an urban population at risk due to the high levels of particulate matter air concentrations, a past particulate matter air pollution episode occurred in Porto region was selected for study. The Comprehensive Air Quality Model with extensions (CAMx) is an Eulerian photochemical dispersion model that simulates the emission, dispersion, chemical reactions, and removal of gaseous and particulate pollutants. To obtain the spatial distribution of particulate matter concentrations in the study area, CAMx was applied to the Porto agglomeration for the selected particulate air pollution episode. Meteorological inputs were obtained by the application of the mesoscale meteorological model MM5 using its nesting capabilities. PM10 simulation results were evaluated against registered concentrations at air quality monitoring stations and were used to estimate population exposure, combining modelling results with information on population regarding their spatial distribution on urban, industrial and rural areas and their time-activity patterns. Preliminary results show that, although high concentrations of PM10 were obtained not exclusively in city centre, exposure is elevated where population density is high. Further research is needed in order to identify more clearly the most significant parameters that affect particulate air pollution in Portuguese urban areas and consequently urban population exposure and health.

The evolution of density‐dependent dispersal in a noisy spatial population model

It is well‐known that dispersal is advantageous in many different ecological situations, e.g. to survive local catastrophes where populations live in spatially and temporally heterogeneous habitats. However, the key question, what kind of dispersal strategy is optimal in a particular situation, has remained unanswered. We studied the evolution of density‐dependent dispersal in a coupled map lattice model, where the population dynamics are perturbed by external environmental noise. We used a very flexible dispersal function to enable evolution to select from practically all possible types of monotonous density‐dependent dispersal functions. We treated the parameters of the dispersal function as continuously changing phenotypic traits. The evolutionary stable dispersal strategies were investigated by numerical simulations. We pointed out that irrespective of the cost of dispersal and the strength of environmental noise, this strategy leads to a very weak dispersal below a threshold density, and dispersal rate increases in an accelerating manner above this threshold. Decreasing the cost of dispersal increases the skewness of the population density distribution, while increasing the environmental noise causes more pronounced bimodality in this distribution. In case of positive temporal autocorrelation of the environmental noise, there is no dispersal below the threshold, and only low dispersal below it, on the other hand with negative autocorrelation practically all individual disperses above the threshold. We found our results to be in good concordance with empirical observations.

Character and causes of population distribution in Shenyang city, China

Character of population distribution is one of the focuses studied by urban geography. Using the fifth national census data as basic data and using areal interpolation method, this paper analyzes character of urban population distribution of Shenyang City, Northeast China, in terms of three aspects of statistical character, spatial auto-correlation and spatial structure. Furthermore, this research analyzes the factors affecting the population distribution of the city. The main conclusions include: 1) There is an obvious structure character of population distribution in the grid with a grain of 300m, which is appropriate scale when researching population distribution in Shenyang City. 2) Urban population distribution has the character of assembling while population density distribution takes on variability in Shenyang City. 3) Population density distribution shows spatial auto-correlation within 7.36km. Spatial heterogeneity of population density is low. 4) Urban center, population distribution barycenter and population density maximum points separate each other. Population density distribution has multi-cores character. 5) Layout of governments, primary schools, middle schools, colleges, hospitals and marketplaces affects population distribution directly. With the increase of distance to these factors, population density decreases as logarithm.

LAKER: learning from past actions to guide future behaviors in ad hoc routing

AbstractIn this paper, we present a location aided knowledge extraction routing (LAKER) protocol for mobile ad hoc networks (MANETs). The novelty of LAKER is that it learns from past actions to guide future behaviors. In particular, LAKER can gradually discover current topological characteristics of the network, such as population density distribution, residual battery map, and traffic load status. This knowledge can be organized in the form of a set of guiding routes, each of which consists of a chain of guiding positions between a pair of source and destination locations. The guiding route information is learned by individual nodes during route discovery phase, and it can be used to guide future route discovery processes in a more efficient manner. LAKER is especially suitable for mobility models where nodes are not uniformly distributed. LAKER can exploit topological characteristics in these models and limit the search space in route discovery processes in a more refined granularity than location aided routing (LAR) protocol. Simulation results show that LAKER outperforms LAR and DSR in term of routing overhead, saving up to 30–45% broadcast routing messages compared to LAR approach. Copyright © 2006 John Wiley & Sons, Ltd.

An analysis of population density distribution in metropolitan areas by the Newling model

An analysis of population density distribution in metropolitan areas by the Newling model

Epidermal-type fatty acid binding protein as a negative regulator of IL-12 production in dendritic cells

Fatty acids and their metabolites have recently been shown to modulate various functions of dendritic cells (DCs) including their differentiation and cytokine production, although the mechanisms underlying their cellular functions are not fully understood. In view of our previous finding that epidermal-type fatty acid binding protein (E-FABP) was exclusively expressed in splenic DCs among FABP family, we examined the phenotype of E-FABP-null mutant mice in order to elucidate the functional significance of E-FABP expression in DCs. Although E-FABP-null mutant mice showed no apparent abnormalities in the population density and subset distribution of DCs as well as the microscopic morphology in the spleen, DCs isolated from E-FABP-null spleen showed enhanced production of IL-12p70, a key cytokine for innate immune responses, in response to appropriate stimuli as compared with wild-type. In real-time PCR, the expression level of IL-12p35 mRNA after LPS stimuli was much higher in mutant DCs when compared with wild-type, while no apparent change of IL-12p40 mRNA level was detected. Phosphorylated forms of p38 mitogen-activated protein kinase (p38MAPK) and IκB-α, molecules critical for IL-12 production, were detected at higher levels in E-FABP-null-mutant DCs after LPS stimuli when compared with wild-type counterparts. Collectively, it is suggested that E-FABP may be a novel negative regulator of IL-12 production in DCs, and this regulation may be exerted via its involvement in the p38MAPK-mediated transcription of IL-12p35.