Changes In Spatial Concentration Research Articles

Spatiotemporal patterns of commercial activities in Exarchia-Neapoli area.

The focus of this paper is the analysis of spatio-temporal patterns of commercial activities in the area of Exarchia-Neapoli, in Athens, during the last decade. A significant downturn during the financial crisis has left its mark on commerce along with all other sectors of the economy in Greece. However, there is poor geographical analysis up to this date, depicting the changes in spatial concentration and dispersion of shops, flourishing and decaying sectors and their spatial footprint. The main purpose of this study is to reveal these transformations in a central mixed-use neighborhood of Athens. The type of commercial activity of ground floor stores and offices in the area is recorded at three different points in time (2009, 2014, 2019). After the collection and categorization of data, spatial analysis was carried out using geostatistical indicators such as mean center and standard deviational ellipse and spatial patterns were determined through nearest neighbor analysis. Τhe analysis over space and time reveals trends and patterns of clustering and avoidance respectively, both within commercial uses and between different ones. Furthermore, their correlation with the centrality of the network (space syntax analysis) reveals not only proximity relationships, but also their strength and resilience over time. Finally, we discuss our findings in relation to the dynamics of commerce in the Exarchia area and propose scaled-up research opportunities.

A study on the occurrence of black water in reservoirs in Eucalyptus Plantation region.

Tianbao reservoir in southern China (surrounded by Eucalyptus plantation) serves as a source of drinking water for the inhabitants. However, the reservoir water experiences black water (BW) of which the cause remains unclear. In this study, field observation and simulated laboratory experiment were conducted to understand the cause of the BW. The diffusive gradient in thin-film (DGT) device monitored the spatial changes in concentration of iron (Fe2+), manganese (Mn2+), sulfide (S2-), and dissolved organic carbon (DOC) at the SWI. The planar optode (PO) showed that hypoxia contributed immensely to the high positive fluxes Fe2+, Mn2+, and S2- measured, which co-precipitated to form black materials (FeS and MnS) at the SWI. The co-precipitation between Fe-S and Mn-S was supported by their significant positive correlation (Fe-S: r > 0.05, p < 0.05, Mn-S: r > 0.2, p < 0.05). Significant reduction (p < 0.05) in tannins concentration from November (strong thermal stratification) to December (weak thermal stratification) indicated that Fe2+ and tannins reacted during the mixing of reservoir water in December due to weak stratification. The simulated experiment confirmed that fresh Eucalyptus leaves produces a significant (p < 0.05) amount of tannins during hypoxia and reacts with Fe2+ to produce black water. A high positive correlation (r > 0.8) between Fe2+ and DOC demonstrated that Fe2+ and DOC combined and contributed to the reservoir water blackening. The study provides a better understanding on the impact of Eucalyptus plantation on water quality and provide guidance for scientific planting of Eucalyptus plantation in reservoir basins in southern China to ensure safe drinking water.

Evaluation of Silica Nanofluids in Static and Dynamic Conditions by an Optical Fiber Sensor.

This work presents an optical fiber dynamic light scattering sensor capable of simultaneously assessing concentration and flow speed of nanofluids. Silica nanoparticles (189 nm) in water were tested, yielding a sensitivity of 0.78288 × 10³ s−1 for static conditions. Then, the sensor was submitted to situations that simulate spatial concentration changes, offering better results than those obtained by traditional mathematical models. Finally, in flow tests, the light backscattered by the nanoparticles were collected by a fiber probe placed parallel to the streamline, whereas intensity values were processed by artificial neural networks. The sensor provides average errors of 0.09 wt% and 0.26 cm/s for concentration and speed measurements, respectively, and can be further applied to assess different types of nanofluids and inline processes.

Umělé radionuklidy v hydrosféře – reziduální kontaminace a vliv Jaderné elektrárny Temelín

Temporal and spatial changes in concentrations of selected radionuclides (tritium, radiostrontium and radiocaesium) were assessed in the parts of the Vltava and Elbe river basins affected by the operation of the Temelin Nuclear Power Plant.

Assessing the Spatial Concentration of Indonesia's Manufacturing Sector: Evidence from Three Decades

Beyond the role of economic forces, many theories of economic geography emphasize the way politics can shape the spacial configuration of economic activity. We investigate the impact of changes in political regimes on industrial concentration using 30 years of data on Indonesian manufacturers. These data span both the reign of Suharto, one of the strongest central governments in Southeast Asia, and its collapse and the subsequent decentralization of power. Using the canonical measure of Ellison and Glaeser, we show that in the mid 1980s, Indonesia’s firms exhibited a similar degree of agglomeration as seen in the United States. Spatial concentration then declined until the 1998 Asian Financial Crisis, and has since begun to rise during the decentralization period. We also measure concentration using the continuous measure developed by Duranton and Overman (2005), and find that the agglomeration exhibited by Indonesian firms is also broadly similar to that documented by Duranton and Overman (2005) for the United Kingdom, although localization drops off more gradually in Indonesia than in the United Kingdom. Using this continuous measure of agglomeration, we identify 32 manufacturing clusters in Indonesia, and investigate the correlates of concentration. We find that the most robust drivers of agglomeration have been natural resources and supply chain linkages, especially with respect to explaining long-term changes in spatial concentration.

Spatially resolved monitoring of powder mixing processes via multiple NIR-probes

Abstract The production of pharmaceutical dosage forms relies on efficient blending of granular components. By monitoring in real-time the blending processes via non-invasive techniques, such as near-infrared (NIR) spectroscopy, the blending end-point can be determined and homogeneity can be guaranteed for a given material blend. In this study an experimental setup with multiple NIR probes attached to a lab-scale blending vessel is presented. The probes were connected to a Fourier-transform NIR spectrometer via an optical fiber switch. Thereby, the blending processes could be “quasi-simultaneously” monitored at multiple positions. Differences in blending behavior in the monitored positions inside the vessel were identified, which would be impossible using a single probe system. The interpretation of the NIR-spectra was done using a chemometric model based on partial least squares regression. Premixed samples with varied content of an active pharmaceutical ingredient were used for calibration. To prevent segregation problems during calibration, it was performed on a rotating disk outside the vessel. Using this multiple-probe setup in combination with the developed chemometric model, segregation and blending inside the vessel were analyzed by observing the temporal and spatial concentration changes, without interruptions caused by manual sampling and/or pausing of the process.

Identifying the Geographical Agglomerations of Manufacturing Industries

The presence of localized industrial aggregation, also from the viewpoint of regional and country growth theories, can be regarded as a potential competitive advantage for regions or nations. While there is an abundance of qualitative analysis of the clustering of single industries and the way in which spatial concentration changes into economies of agglomeration, for a long time it was difficult to undertake quantitative work on the same subjects because of the lack of any econometrically operational definition of industrial agglomeration. Only recently, thanks to the work of Ellison and Glaeser (1997), it has become possible to measure the geographical concentration of production in a statistically correct way, excluding from the agglomeration phenomena cases of industrial concentration due to a random distribution of a small number of large plants. Following these intuition many other measures of agglomeration have been proposed. The empirical evidence provided by this literature confirms that most industries are, in a large number of countries, more highly clustered than a model of random spatial distribution of firms might predict. In these paper, starting from the work of Ellison and Glaeser we derive an algorithm to select and map industrial agglomeration. We propose, specifically, a test of the industrial specialization of an area based on the null hypothesis of absence of agglomeration advantages: in this way we can select the areas that pass the test and build around them a set of neighbouring areas that represent the space of probable diffusion of proximity advantages.Then, we apply the algorithm to the geographical distribution of manufacturing activities in Italy and give a description of the main features of agglomerated areas in the country. We are able, among other things, to verify the high variability that subsists among Italian agglomerations in connection with their dimension, characteristics of specialization and presence of large firms. The considerable dissimilarities found in the structural features of agglomerations confirm that, in econometric research into the advantages of producing in an industrial agglomeration, a strictly dichotomous approach can be strongly misleading.Finally, we discuss the conceptual differences between the “industrial agglomeration” obtained with our algorithm and the Marshallian notion of “industrial district” that represent a key analytical category in the literature on local development models in Italy.

DIFS—a modelling and simulation tool for DGT induced trace metal remobilisation in sediments and soils

The technique of Diffusive Gradients in Thin-films (DGT) can measure in situ fluxes of trace metals in sediments. Interpretation of these measurements requires a numerical model of trace metal reaction and transport in sediments. The DIFS (DGT Induced Fluxes in Sediments) model has permitted quantitative interpretation of DGT measurements in terms of fundamental kinetic and equilibrium resupply parameters. DIFS is here further refined and developed into a software tool which both simulates temporal and spatial changes in concentrations of trace metals in solid and solution phases in sediments during in situ DGT deployments, and estimates resupply parameters from experimental data. The basis of the DIFS model is a pair of linked parabolic PDEs describing dissolved and sorbed trace metal concentrations in the sediment and DGT device. These are solved by the Method of Lines using standard ODE solvers. The solutions are processed to obtain the DGT response. The use of the software, in particular the format of the text file containing input parameters, is described. Illustrative examples of the type of behaviour predicted for DGT by DIFS are provided.

Spatial changes in the concentrations and activities of amylase and trypsin in Euphausia superba. A comparison between activity measurement and immunoquantitation

Two digestive enzymes: alpha amylase and trypsin were purified by affinity chromatography from the antarctic euphausiid Euphausia superba and the corresponding antibodies developed in male New-Zealand rabbits. Electrophoresis of purified enzymes yielded 4 isozymes for amylases and 6 for trypsin. The purification level was relatively low for amylase because of a high molecular weight contaminant with a low level of activity. Rocket immunoelectrophoresis of amylase showed three precipitin lines; a single line was obtained for trypsin. The antiserum obtained at a dilution of 1% presented a good linearity of the response between 60 to 1000 ng of pure trypsin. Both enzyme concentrations were measured by the quantitative method of rocket immunoelectrophoresis for different stations of the FIBEX cruise. Enzyme activities and concentration displayed significant spatial changes and a certain degree of association with the developmental stages sampled. Several inconsistencies in the relationships between growth stages and enzyme rates or quantities suggested that the spatial variations were not solely related to specific growth requirements but to combine effects of both physiological and environmental factors. Comparison of the spatial changes in concentration and activity showed that the changes in enzyme concentration were in a large part (60% of the total variance) responsible for the activity changes. The results strongly suggest that enzyme synthesis and degradation ensured the gross regulation of activity while modifications of the kinetic properties could be implicated in the fine tuning.

Religion and Regional Culture: Patterns of Concentration and Change among American Religious Denominations, 1952-1980

Religious denominations are viewed as indicators of regional cultural distinctiveness in the United States. Census-type adherence data for 1952, 1971, and 1980 are used to examine changes in spatial concentration within religious groups, and in relation to general population trends. Contrary to expectations, for both the 1952-1971 and 1971-1980 periods these broadly representative denominational data exhibit remarkable stability rather than change. The implications of these patterns for future research on religious trends and their impact on regional culture are discussed.

Glucose exchanges in a salt marsh‐estuary: Biological activity and chemical measurements1

Spatial changes in concentrations and uptake rates of glucose in a Spartina alterniflora salt marsh estuary (Duplin River, Sapelo Island, Georgia) were determined to assess the source and fate of glucose in the system. Concentrations were highly variable along the length of the river and over several tidal periods, with high values (5–20 µg·liter −1) in March and low values (1–10 µg·liter −1) in August. Glucose was rapidly cycled in the headwaters as indicated by uptake rates and turnover times. Respiration of added [14C]glucose was relatively constant within the system and temporally.Two striking features of this system were a glucose gradient from Doboy Sound (high glucose) water toward the transitional zone (low glucose) and another one from the headwaters (high glucose) toward the transitional zone, and a decrease in activity in the 3‐µm size fraction from Doboy Sound toward the transitional zone and an increase in activity from this zone toward the headwaters. Conclusions based on various hydrological and biological time scales indicate that glucose exchange associated with the tides (i.e. glucose mixing between zones) is small compared to recycling within the system.

Cell communication by periodic cyclic-AMP pulses.

At the surface of aggregating cells of the slime mould, Dictyostelium discoideum, two different sites interacting with extracellular cAMP are detectable: binding sites and cycl-nucleotide phosphodiesterase. Both sites are developmentally regulated. An adequate stimulus for the chemoreceptor system in D. discoideum is the change of cAMP concentration in time, rather than concentration per se: long-term binding of cAMP causes only short-term response. The system is, consequently, adapted to the recognition of pulses rather than to steady-state concentrations of cAMP. The ce,lls are, nevertheless, able to sense stationary spatial gradients and to respond to them by chemotactic orientation. The possibility is discussed that they do so by transforming spatial concentration changes into temporal ones, using extending pseudopods as sensors. The cAMP recognition system is part of a molecular network involved in the generation of spatio-temporal patterns of cellular activities. This system controls the periodic formation of chemotactic signals and their propagation from cell to cell. The phosphodiesterase limits the duration of the cAMP pulses and thus sharply separates the periods of signalling; the binding sites at the cell surface are supposed to be the chemoreceptors. The control of cellular activities via cAMP receptors can be studied with biochemical techniques with cell suspensions in which spatial inhomogeneities are suppressed by intense stirring, whereas the temporal aspect of the spatiotemporal pattern is preserved. Under these conditions it can be shown that the extracellular cAMP concentration changes periodically, and that the phase of the cellular oscillator can be shifted by external pulses of cAMP. It can also be shown that small cAMP pulses induce a high output of cAMP, which demonstrates signal amplification, a function necessary for a cellular relay system.