Home About us Contact
|
Home About us Contact | ||
|
|
||
Square Grid (square + grid)
Selected AbstractsAnalysing soil variation in two dimensions with the discrete wavelet transformEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2004R. M. Lark Summary Complex spatial variation in soil can be analysed by wavelets into contributions at several scales or resolutions. The first applications were to data recorded at regular intervals in one dimension, i.e. on transects. The theory extends readily to two dimensions, but the application to small sets of gridded data such as one is likely to have from a soil survey requires special adaptation. This paper describes the extension of wavelet theory to two dimensions. The adaptation of the wavelet filters near the limits of a region that was successful in one dimension proved unsuitable in two dimensions. We therefore had to pad the data out symmetrically beyond the limits to minimize edge effects. With the above modifications and Daubechies's wavelet with two vanishing moments the analysis is applied to soil thickness, slope gradient, and direct solar beam radiation at the land surface recorded at 100-m intervals on a 60 × 101 square grid in south-west England. The analysis revealed contributions to the variance at several scales and for different directions and correlations between the variables that were not evident in maps of the original data. In particular, it showed how the thickness of the soil increasingly matches the geological structure with increasing dilation of the wavelet, this relationship being local to the strongly aligned outcrops. The analysis reveals a similar pattern in slope gradient, and a negative correlation with soil thickness, most clearly evident at the coarser scales. The solar beam radiation integrates slope gradient and azimuth, and the analysis emphasizes the relations with topography at the various spatial scales and reveals additional effects of aspect on soil thickness. [source] Effectiveness in cleaning oval-shaped root canals using Anatomic Endodontic Technology, ProFile and manual instrumentation: a scanning electron microscopic studyINTERNATIONAL ENDODONTIC JOURNAL, Issue 6 2005O. Zmener Abstract Aim, To compare in vitro the cleanliness of root canal walls in oval-shaped root canals following automated or manual instrumentation. Methodology, Forty-five oval-shaped single-rooted maxillary and mandibular premolars with straight canals were divided into three groups of 15. Automated canal preparation was performed using Anatomic Endodontic Technology (AET, group 1) and the ProFile system (group 2). Manual instrumentation (group 3) was performed with K-Flexofiles. Irrigation was performed using alternately 5.25% NaOCl and 17% EDTA, followed by rinsing with saline. The roots were split longitudinally into halves and the canals examined at ×200 and ×400 in a scanning electron microscope. The presence of debris and smear layer was recorded at distances of 1, 5 and 10 mm from the working length using a three-step scoring scale and a 300 ,m square grid. Mean scores for debris and smear layer were calculated and statistically analysed for significance (P < 0.05) between and within groups, using the Kruskal,Wallis nonparametric anova and Dunn's tests. Results, At 1, 5 and 10-mm levels the root canals prepared with AET had significantly less surface debris and smear layer on the canal walls compared with canals prepared with ProFile or manual instrumentation. For all three groups significantly lower mean smear layer scores (P < 0.05) were recorded at 5 and 10-mm levels compared with the 1 mm level. Significantly lower mean debris scores (P < 0.05) were also recorded at 5 and 10-mm levels for the AET group whereas no significant differences were found between the three levels for the ProFile and manual instrumentation groups. Conclusions, Although better instrumentation scores were obtained in canals prepared with AET, complete cleanliness was not achieved by any of the techniques and instruments investigated. [source] Characterization and reconstruction of a rock fracture surface by geostatisticsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 9 2002A. Marache Abstract It is well understood that, in studying the mechanical and hydromechanical behaviour of rock joints, their morphology must be taken into account. A geostatistical approach has been developed for characterizing the morphology of fracture surfaces at a decimetre scale. This allows the analysis of the spatial variability of elevations, and their first and second derivatives, with the intention of producing a model that gives a numerical three-dimensional (3D) representation of the lower and upper surfaces of the fracture. Two samples (I and II) located close together were cored across a natural fracture. The experimental data are the elevations recorded along profiles (using recording steps of 0.5 and 0.02 mm, respectively, for the samples I and II). The goal of this study is to model the surface topography of sample I, so getting estimates for elevations at each node of a square grid whose mesh size will be, for mechanical purposes, no larger than the recording step. Since the fracture surface within the sample core is not strictly horizontal, geostatistical methods are applied to residuals of elevations of sample I. Further, since structural information is necessary at very low scale, theoretical models of variograms of elevations, first and second derivatives are fitted using data of both that sample I and sample II. The geostatistical reconstructions are computed using kriging and conditional simulation methods. In order to validate these reconstructions, variograms and distributions of experimental data are compared with variograms and distributions of the fitted data. Copyright © 2002 John Wiley & Sons, Ltd. [source] Synthesis, Crystal Structures and Photoluminescence Properties of Two 2D Coordination Polymer Compounds with Drug Ligand EnoxacinCHINESE JOURNAL OF CHEMISTRY, Issue 7 2006Liang-Cai Yu Abstract Two new 2D coordination polymers of [M(Enox)2]·C2H5OH (MZn, 1 and Co, 2; HEnox=1,4-dihydro- 1-ethyl-6-fluoro-4-oxo-7-piperazine-1,8-naphtyridine-3-carboxylic acid) were synthesized under hydrothermal conditions. The single crystal X-ray diffraction analyses showed that 1 and 2 are isostructural. The Zn(II) in 1 and Co(II) ions in 2 are six-coordinated in an octahedral environment with an equatorial plane composed of four oxygen atoms:two of them from the 4-oxo and the other two from 3-carboxylate of two coordinated Enox ligands, forming a stable six-membered chelating ring with the apical positions occupied by two N atoms of the piperazinyl rings. Thus, the molecules were self-assembled into a 2D neutral square grid with cavity dimensions of 1.3399 nm×1.3399 nm for 1 and 1.3389 nm×1.3389 nm for 2, respectively. Compound 1 emits strong blue fluorescence on irradiation by UV light in the solid state at room temperature. [source] Analysis of a Distribution of Point Events Using the Network-Based Quadrat MethodGEOGRAPHICAL ANALYSIS, Issue 4 2008Shino Shiode This study proposes a new quadrat method that can be applied to the study of point distributions in a network space. While the conventional planar quadrat method remains one of the most fundamental spatial analytical methods on a two-dimensional plane, its quadrats are usually identified by regular, square grids. However, assuming that they are observed along a network, points in a single quadrat are not necessarily close to each other in terms of their network distance. Using planar quadrats in such cases may distort the representation of the distribution pattern of points on a network. The network-based units used in this article, on the other hand, consist of subsets of the actual network, providing more accurate aggregation of the data points along the network. The performance of the network-based quadrat method is compared with that of the conventional quadrat method through a case study on a point distribution on a network. The ,2 statistic and Moran's I statistic of the two quadrat types indicate that (1) the conventional planar quadrat method tends to overestimate the overall degree of dispersion and (2) the network-based quadrat method derives a more accurate estimate on the local similarity. The article also performs sensitivity analysis on network and planar quadrats across different scales and with different spatial arrangements, in which the abovementioned statistical tendencies are also confirmed. [source] Science Driven Restoration: A Candle in a Demon Haunted World,Response to Cabin (2007)RESTORATION ECOLOGY, Issue 2 2007Christian P. Giardina Abstract Cabin (2007) asks whether formal science is an effective framework and methodology for designing and implementing ecological restoration programs. He argues that beyond certain ancillary benefits, restoration science has little of practical value to offer the practice of restoration. He goes on to suggest that restoration science most often represents an impediment to restoration practice because an "ivory tower" mentality limits the utility of experiments and diverts research dollars away from answering practical questions. His conclusion is that a nonscientific gardening approach may be more effective at restoring degraded ecosystems. We disagree with this perspective because: (1) restoration science has moved beyond exclusively using "square grids" placed on small patches of land to examine treatment effects on species representation; (2) Cabin's critique greatly undervalues the contribution of science to restoration practice even where the input of restoration scientists is not directly evident; and (3) the practice of restoration is unlikely to advance beyond small-scale and truly haphazard successes without well-designed studies that can provide peer-reviewed and widely accessible published information on the mechanisms underlying both successes and failures. We conclude that through integration with other disciplines, restoration science increasingly will provide novel approaches and tools needed to restore ecosystem composition, structure, and function at stand to landscape scales. As with the broader role of science in the human enterprise (Sagan 1996), the contribution of restoration science to restoration practice can only grow as the discipline matures. [source] catena -Poly[[[tetraaquazinc(II)]-,-4-amino-3,5-di-3-pyridyl-4H -1,2,4-triazole] sulfate monohydrate] and poly[[bis(,-4-amino-3,5-di-4-pyridyl-4H -1,2,4-triazole)diaquacopper(II)] dinitrate octahydrate]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2009Hai-Ying Wang The isomeric bent triazole-containing ligands 4-amino-3,5-di-3-pyridyl-4H -1,2,4-triazole (L1) and 4-amino-3,5-di-4-pyridyl-4H -1,2,4-triazole (L2) have been used to create the two novel title complexes catena -poly[[[tetraaquazinc(II)]-,-4-amino-3,5-di-3-pyridyl-4H -1,2,4-triazole] sulfate monohydrate], {[Zn(C12H10N6)(H2O)4]SO4·H2O}n, (I), and poly[[diaquabis(,-4-amino-3,5-di-4-pyridyl-4H -1,2,4-triazole)copper(II)] dinitrate octahydrate], {[Cu(C12H10N6)2(H2O)2](NO3)2·8H2O}n, (II). The ZnII and CuII atoms are all six-coordinated in approximately octahedral environments. Compound (I) presents a sinusoidal chain generated by ZnO4 cores which are bridged by L1 ligands in a cisoid conformation. These sinusoidal chains are bound to each other by O,H...O hydrogen bonds between coordinated water molecules of neighboring chains into a two-dimensional network. These layers stack in an ,ABAB, sequence and are further linked into a three-dimensional framework through O,H...N hydrogen bonds between coordinated water molecules and the N atoms of the triazole rings. In (II), the CuII centers are bridged by the L2 ligands to form a two-dimensional network with square grids. All of the two-dimensional nets also stack alternately along the crystallographic a axis. Neighboring layers are further linked into a three-dimensional framework via interlayer N,H...N hydrogen bonds between ,NH2 groups of the triazole rings and the N atoms in the triazole rings. [source] | ||||||||||