Three-dimensional Spatial Analysis Research Articles

The validation of the parallel three-dimensional solver for analysis of optical plasmonic bi-periodic multilayer nanostructures

Fundamentals of the three-dimensional spatial harmonic analysis (SHA) approach are reviewed, and the advantages of a fast-converging formulation versus the initial formulation are emphasized with examples using periodic plasmonic nanostructures.

Interactions among phosphorus, pH and Eh in reforested mangroves, Vietnam: a three-dimensional spatial analysis

Sediment reduction is frequently proposed to increase available phosphorus (P) but several studies found also decreases. Another important factor for P liberation is the pH. We investigated the relative importance of Eh and pH on P cycling in reforested mangroves. Sediment P compounds, pH and Eh were analysed over depth along five transects of two areas in the Saigon River Delta and compared with leaf P levels. A three-dimensional spatial approach was used to investigate pH and Eh effects on P compound distribution at different sediment depth and locate layers of predominant P uptake. Along an inundation gradient, submergence durations of 254 to 2 days per year caused a large Eh gradient within the top 20 cm, whereas Eh response was small within 20–45 cm depth. At individual layers, a correlation between Eh and Al/Fe–P was only found in the upper depth interval (0–20 cm). No significant effect of Eh or Al/Fe–P on Morgan-P (available P) was detected. Minor effects on P composition changes by the Eh were caused through generally strongly reduced sediment at deeper layers (>20 cm). In contrast, pH variations produced extreme differences in both, Ca–P and available P content at layers of apparently predominant P uptake (>20 cm). As available P was correlated with Ca–P (p < 0.001), leaf P (p < 0.001) and pH (non linear correlation) it is likely that the pH sensitive Ca–P fraction is a more effective source for mangrove tree growth than Al/Fe–P. The predominant pH effect on P uptake within these reforested mangroves differs from a proposed reduction-governed P cycling in wetlands.

Refining the definition of cultural levels at Karabi Tamchin: a quantitative approach to vertical intra-site spatial analysis

The visual identification of archaeological levels can be difficult when stratigraphy is complex. This study emphasizes the importance of three-dimensional intra-site spatial analysis as a means of testing the integrity of archaeological levels, including the identification of palimpsest deposits. A geographical information system (GIS) is applied to a three-dimensional spatial analysis of lithic and bone distributions from Karabi Tamchin, a Middle Palaeolithic site from the Crimea, Ukraine. K-means statistical clustering is combined with a series of data transformations to identify and interpret the vertical and horizontal spatial organization of the site. The results indicate that K-means cluster analysis, used in conjunction with GIS, provides an exceptional method of identifying discrete clusters of archaeological materials in three dimensions. Through an analysis of cluster contents within levels, it is possible to reconstruct and compare patterns of spatial organization at Karabi Tamchin, contributing to current debates regarding the cognitive complexity of Neanderthal populations.

Simulated annealing and object point processes: Tools for analysis of spatial patterns

This paper introduces a three-dimensional object point process—the Bisous model—that can be used as a prior for three-dimensional spatial pattern analysis. Maximization of likelihood or penalized-likelihood functions based on this model requires global optimization techniques, such as the simulated annealing algorithm. Theoretical properties of the model are discussed and the convergence of the proposed optimization method is proved. Finally, a simulation study is presented.

Three-dimensional analysis of particulates in mineral processing systems by cone beam X-ray microtomography

In general X-ray-computed tomographic (CT) techniques are capable of providing three-dimensional images of the internal structure of opaque materials in a nondestructive manner. The unique cone beam geometry allows acquisition of all two-dimensional projections with only one rotation of the sample, thus providing for fast data acquisition and better X-ray utilization, as a complete two-dimensional detector array receives the cone-shaped flux of rays. Thus, an isotropic three-dimensional volume can be reconstructed without the mechanical translation and the stacking of sequential slices, as is the case for more conventional CT scanners. In this regard, a state-of-the-art, custom designed X-ray microtomography facility to provide very detailed three-dimensional spatial analysis of packed beds of multiphase particles was installed and is in operation at the University of Utah. The reconstructed three-dimensional tomographic volume allows for spatial resolution as small as 5 μm for sample dimensions of up to 40 mm in diameter. Utilization of this custom-designed cone-beam X-ray microtomography facility for the analysis of particulate systems in three dimensions is discussed. Applications described include coal washability analysis for the design and operation of coal-preparation plants, liberation analysis for the evaluation of grinding practice and separation efficiency, mineral exposure analysis for the prediction of the ultimate recovery from heap-leaching operations, three-dimensional particle shape analysis to classify particle populations and, finally, analysis of the pore-structure network of packed particle beds for simulation of flow through such porous structures as encountered infiltration and heap leaching. The initial results from these studies demonstrate the potential utility of detailed three-dimensional microCT information for improved design and operation of mineral processing methods.

Cone beam X-ray microtomography — a new facility for three-dimensional analysis of multiphase materials

As the techniques and resolution for three-dimensional spatial analysis have advanced in the last deauie, it is now possible to map in detail the microstructure ofmllltipizase materials in three-dimensional digital space. In this regard, three-dimensiollal X-ray microtomography offers a unique imaging capability. Sparial resolution on the order of lO pm can be achieved ,,'/ith the lise of microfocus X-ray generators. Recently, a state-oIfhe-art cone beam X-ray microtomography system was installed at the University of Utah for the quantitative analysis of multiphase materials in three dimensions. This facility was designed to obtain 2,048 by 2,048-pixel reconstruction overa lO-mm diameter, while also allowingfor the imaging of somewhat larger (40-mm) objects. The system is capable of handling high-density materials, even materials having a density as high as 8.0 glcm 3 . This ullique, one-of-a-kind instrument can he used to obtain three-dimensional spatial reconstruction for many applications, such as three-dimensional liberation analysis, pore structure analysis of particle beds during filtration and the air-void system of concrete structures. The utilization of X-ray microtomography not only allows for the quantitative analyst.\· of multiphase systems but also allows for the textural characterization and determination of phase continuity. This paper presents injomwtion regarding the current use of this new facility and a review of potential applications for the advanced analytical system.

Three-dimensional materials analysis by confocal Raman microspectroscopy

Two- and three-dimensional spatial analysis of various composite materials was performed with a scanning confocal Raman microspectrometer. Samples include TiO(2) microparticles, mixtures of polymers, and the surface of an older Eprom computer chip. In the last case both structural and compositional information was obtained by means of comparing the signal intensity of the Rayleigh line with that of the silicon Raman line at 520 cm(-1). The spatial compositions of a pain-relief medicine and a pharmaceutical salt mixture could be visualized from characteristic Raman lines of the components.

Temporal and three-dimensional spatial analyses of the frequency-magnitude distribution near Long Valley Caldera, California

SUMMARY The 3-D distribution of the b value of the frequency‐magnitude distribution is analysed in the seismically active parts of the crust near Long Valley Caldera, California. The seismicity is sampled in spherical volumes, containing N=150 earthquakes and centred at nodes of a grid separated by 0.3 km. Significant variations in the b value are detected, with b ranging from b#0.6 to b#2.0. High b-value volumes are located near the resurgent dome, and at depths below 5 km at Mammoth Mountain. b values are found to be much lower south of the Long Valley Caldera. We interpret this to indicate that an active magma body has advanced from depths below 8 km to depths of 4 to 5 km beneath Mammoth Mountain in 1989, and that anomalous crust, either highly fractured or containing unusually high pore pressure, such as is the case in the vicinity of active magma bodies, exists north of the seismically active area beneath the resurgent dome at all depths. We also investigate the spatial distribution of temporal variations of the frequency‐magnitude distribution by introducing diVerential b-value maps. b values increased from b#0.8 to b#1.5 underneath Mammoth Mountain at the onset of the 1989 earthquake swarm and remained high thereafter. This suggests that an intrusion permanently altered the average distribution of cracks at 5‐10 km depth, or that the pore pressure permanently increased. We propose that high b values are a necessary (but not suYcient) condition near a magmatic body, and therefore spatial b-value mapping can be used to aid in the identification of active magma bodies.

Telomeres cluster de novo before the initiation of synapsis: a three-dimensional spatial analysis of telomere positions before and during meiotic prophase.

We have analyzed the progressive changes in the spatial distribution of telomeres during meiosis using three-dimensional, high resolution fluorescence microscopy. Fixed meiotic cells of maize (Zea mays L.) were subjected to in situ hybridization under conditions that preserved chromosome structure, allowing identification of stage-dependent changes in telomere arrangements. We found that nuclei at the last somatic prophase before meiosis exhibit a nonrandom, polarized chromosome organization resulting in a loose grouping of telomeres. Quantitative measurements on the spatial arrangements of telomeres revealed that, as cells passed through premeiotic interphase and into leptotene, there was an increase in the frequency of large telomere-to-telomere distances and a decrease in the bias toward peripheral localization of telomeres. By leptotene, there was no obvious evidence of telomere grouping, and the large, singular nucleolus was internally located, nearly concentric with the nucleus. At the end of leptotene, telomeres clustered de novo at the nuclear periphery, coincident with a displacement of the nucleolus to one side. The telomere cluster persisted throughout zygotene and into early pachytene. The nucleolus was adjacent to the cluster at zygotene. At the pachytene stage, telomeres rearranged again by dispersing throughout the nuclear periphery. The stage-dependent changes in telomere arrangements are suggestive of specific, active telomere-associated motility processes with meiotic functions. Thus, the formation of the cluster itself is an early event in the nuclear reorganizations associated with meiosis and may reflect a control point in the initiation of synapsis or crossing over.

Biomechanics of the hip: forces exerted during walking.

Since the work of Pauwels, the forces exerted on the coxofemoral joint during walking have been studied either in different spatial planes (frontal, sagittal and horizontal) or by three-dimensional spatial analysis. Starting from the findings of our own studies, our aim was to compare the two methods of analysis (two-dimensional and three-dimensional) in order to provide a better understanding of the benefits and limitations of each method. In pursuit of this aim, we studied the pressure forces exerted on the coxofemoral joint, using a geometric plane technique following a method similar to that of Pauwels [20], and with a three-dimensional modelling technique using the finite element method. The material, taken from the published literature, was the same in both our studies. The results are expressed in terms of the size and orientation of the pressure force exerted on the coxofemoral joint during the monopodal weightbearing phase of walking. A comparison of these two methods of analysis clearly demonstrates the simplicity of two-dimensional analysis (which must incorporate as a minimum the frontal plane and the sagittal plane) and the richness of the three-dimensional analysis. The latter method, by appropriate manipulation of the information obtained, provides a starting point for computer simulations performed with the aim of testing a biomechanical or therapeutic hypothesis.

Neonatal deafening alters nonpyramidal dendrite orientation in auditory cortex: a computer microscope study in the rabbit.

In order to examine the influence of afferent input on nonpyramidal dendrite development in the auditory cortex, unilateral deafening was carried out in neonatal rabbits at birth, approximately 6 days prior to the onset of hearing. Deafening was produced by surgical removal of the incus and stapes ossicles, aspiration of the cochlear perilymph, and kanamycin injection into the oval window. At 60 days of age, acoustic stimulation of the deafened ear was unable to evoke auditory brainstem responses. The brains of experimental and littermate control rabbits were processed according to the Golgi-Cox Nissl method. The dendritic systems of lamina III/IV spine-free nonpyramidal cells in the auditory cortex contralateral to the deafened ear were digitized from 340-micron-thick coronal sections with the aid of a computer microscope. Three-dimensional spatial and statistical analyses revealed that nonpyramidal dendrite length in neonatally deafened rabbits increased 27% relative to littermate controls. A fan-in projection analysis revealed that the increased dendrite length in the deafened animals was maximum in the tangential direction and toward the white matter. Computer rotation of digitized neurons from neonatally deafened rabbits also revealed evidence of abnormal dendritic growth in the form of recurved dendrites. We interpret our results to indicate that unilateral cochlear destruction early in development causes a reorganization of the ascending auditory pathway which extends to the contralateral cerebral cortex. Because the auditory cortex contralateral to the deafened ear still receives acoustic input from the undamaged ipsilateral ear, normal nonpyramidal dendritic growth in the auditory cortex is, in part, dependent upon afferent activity arising from both ears.

Analysis of the VDT-worker interface

Abstract A three-dimensional spatial analysis of the VDT-worker interface is given. The relationships between the various parameters involved and the variables in the manual and visual fields are computed, using anthropometric measurements taken from 14 individuals. The effects of different postures are discussed. Fixed-keyboard and separate-keyboard VDTs are compared.