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Resolution Data (resolution + data)
Kinds of Resolution Data Terms modified by Resolution Data Selected AbstractsGeostatistical Prediction and Simulation of Point Values from Areal DataGEOGRAPHICAL ANALYSIS, Issue 2 2005Phaedon C. Kyriakidis The spatial prediction and simulation of point values from areal data are addressed within the general geostatistical framework of change of support (the term support referring to the domain informed by each measurement or unknown value). It is shown that the geostatistical framework (i) can explicitly and consistently account for the support differences between the available areal data and the sought-after point predictions, (ii) yields coherent (mass-preserving or pycnophylactic) predictions, and (iii) provides a measure of reliability (standard error) associated with each prediction. In the case of stochastic simulation, alternative point-support simulated realizations of a spatial attribute reproduce (i) a point-support histogram (Gaussian in this work), (ii) a point-support semivariogram model (possibly including anisotropic nested structures), and (iii) when upscaled, the available areal data. Such point-support-simulated realizations can be used in a Monte Carlo framework to assess the uncertainty in spatially distributed model outputs operating at a fine spatial resolution because of uncertain input parameters inferred from coarser spatial resolution data. Alternatively, such simulated realizations can be used in a model-based hypothesis-testing context to approximate the sampling distribution of, say, the correlation coefficient between two spatial data sets, when one is available at a point support and the other at an areal support. A case study using synthetic data illustrates the application of the proposed methodology in a remote sensing context, whereby areal data are available on a regular pixel support. It is demonstrated that point-support (sub-pixel scale) predictions and simulated realizations can be readily obtained, and that such predictions and realizations are consistent with the available information at the coarser (pixel-level) spatial resolution. [source] The benefits of rapid 3D fMRIINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 1 2010Martin A. Lindquist Abstract Functional magnetic resonance imaging (fMRI) provides the ability to image blood dynamics through the entire brain with a high spatial resolution. However, the temporal resolution is much slower than the underlying neuronal activity one seeks to infer. Recent developments in rapid imaging allow 3D fMRI studies to be performed at a temporal resolution of 100 ms; a 10-fold increase compared to standard approaches. This increase in temporal resolution offers a number of potential benefits. First, it allows the focus of analysis to be shifted from changes in blood flow taking place 5,8 s after neuronal activity to more transient changes taking place immediately following activation. We argue that studying these changes provides valuable information about the relative timing of activation across different regions of the brain, which is crucial for inferring brain pathways. Second, rapid imaging allows for the efficient modeling of physiological artifacts without problems with aliasing; something that is difficult at standard resolutions. We illustrate how removal of these artifacts provides the increase in signal-to-noise ratio required for studying the subtle changes in oxygenation we are interested in. Finally, we show how high temporal resolution data provides the opportunity to focus the analysis on the rate of change in oxygenation rather than the level of oxygenation as is the current practice. The price of performing rapid imaging studies is a decrease in spatial resolution. However, we argue that the resolution is still comparable to the effective resolution used in most fMRI studies. We illustrate our approach using two fMRI data sets. © 2010 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 20, 14,22, 2010 [source] Using habitat distribution models to evaluate large-scale landscape priorities for spatially dynamic speciesJOURNAL OF APPLIED ECOLOGY, Issue 1 2008Regan Early Summary 1Large-scale conservation planning requires the identification of priority areas in which species have a high likelihood of long-term persistence. This typically requires high spatial resolution data on species and their habitat. Such data are rarely available at a large geographical scale, so distribution modelling is often required to identify the locations of priority areas. However, distribution modelling may be difficult when a species is either not recorded, or not present, at many of the locations that are actually suitable for it. This is an inherent problem for species that exhibit metapopulation dynamics. 2Rather than basing species distribution models on species locations, we investigated the consequences of predicting the distribution of suitable habitat, and thus inferring species presence/absence. We used habitat surveys to define a vegetation category which is suitable for a threatened species that has spatially dynamic populations (the butterfly Euphydryas aurinia), and used this as the response variable in distribution models. Thus, we developed a practical strategy to obtain high resolution (1 ha) large scale conservation solutions for E. aurinia in Wales, UK. 3Habitat-based distribution models had high discriminatory power. They could generalize over a large spatial extent and on average predicted 86% of the current distribution of E. aurinia in Wales. Models based on species locations had lower discriminatory power and were poorer at generalizing throughout Wales. 4Surfaces depicting the connectivity of each grid cell were calculated for the predicted distribution of E. aurinia habitat. Connectivity surfaces provided a distance-weighted measure of the concentration of habitat in the surrounding landscape, and helped identify areas where the persistence of E. aurinia populations is expected to be highest. These identified successfully known areas of high conservation priority for E. aurinia. These connectivity surfaces allow conservation planning to take into account long-term spatial population dynamics, which would be impossible without being able to predict the species' distribution over a large spatial extent. 5Synthesis and applications. Where species location data are unsuitable for building high resolution predictive habitat distribution models, habitat data of sufficient quality can be easier to collect. We show that they can perform as well as or better than species data as a response variable. When coupled with a technique to translate distribution model predictions into landscape priority (such as connectivity calculations), we believe this approach will be a powerful tool for large-scale conservation planning. [source] Home range and seasonal movements of Giraffa camelopardalis angolensis in the northern Namib DesertAFRICAN JOURNAL OF ECOLOGY, Issue 3 2009*Article first published online: 23 FEB 200, Julian Fennessy Abstract Estimates of home range size of giraffe in the northern Namib Desert were on average larger than those in other populations. In particular, the largest individual home range of any giraffe bull (1950 km2) was recorded , correlated with low population density, reduced forage density and increased searching for receptive cows. The predominant pattern of movement was linear, along the riparian environments, however, large-scale irregular movements into tributaries and other areas were also recorded. Small-scale movements by bulls into the mountains above the Hoarusib River as well as by cows into the northern tributaries of the Hoanib River were observed. Seasonal movements of giraffe were not as distinctive as those in other giraffe populations. Small-scale habitat segregation was observed in the Hoarusib River study area with giraffe cows foraging only in the Gomatum River during the hot-dry season. The first ever study of GPS satellite collared giraffe provided some of the highest resolution data on giraffe movements to date, including strong biphasic movement behaviour of giraffe over 24-h periods. Résumé Les estimations de la taille du domaine vital des girafes du nord du désert du Namib furent en général plus grandes que celles des autres populations. En particulier, on a enregistré le plus grand domaine vital individuel pour une girafe mâle (1950 km²) , lié avec une faible densité de population, une densité de nourriture réduite et une recherche accrue de femelles réceptives. Le schéma de déplacement dominant était linéaire, le long des environnements riverains, bien que l'on ait aussi enregistré d'importants déplacements irréguliers vers des affluents et vers d'autres régions. Des déplacements de faible ampleur furent aussi observés, de mâles dans les montagnes au-dessus de la rivière Hoarusib et de femelles vers les affluents plus au nord de la rivière Hoanib. Les déplacements saisonniers des girafes n'étaient pas aussi typiques que ceux d'autres populations de girafes. Une ségrégation de l'habitat à petite échelle fut observée dans la zone d'étude de la rivière Hoarusib, avec des femelles qui ne mangeaient que dans le bassin de la rivière Gomatum pendant la saison chaude et sèche. La première étude jamais réalisée d'une girafe équipée d'un collier àémetteur GPS a fourni certaines des données les plus précises sur les déplacements de girafes à ce jour, y compris un comportement en deux phases de déplacement très nettes par période de 24 heures. [source] Applications of ACORN to data at 1.45 Å resolutionJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2004V. Rajakannan One of the main interests in the molecular biosciences is in understanding structure,function relations and X-ray crystallography plays a major role in this. ACORN can be used as a comprehensive and efficient phasing procedure for the determination of protein structures when atomic resolution data are available. An initial model can automatically be built by ARP/wARP followed by REFMAC for refinement. The , helices and , sheets occurring in many protein structures can be taken as starting fragments for structure solution in ACORN. ACORN, along with ARP/wARP followed by REFMAC, can be an ab initio method for solving protein structure for which data are better than 1.2 Å (atomic resolution). Attempts are here made in extending its applications to real data at 1.45 Å resolution and also to truncated data at 1.6 Å resolution. Two previously known structures, congerin II and alkaline cellulase N257, were resolved using the above approach. Automatic structure solution, phasing and refinement for real data at still lower resolutions for proteins of various complexities are being carried out. Data mining of the secondary structural features using PDB is being carried out for this new approach for `seed-phasing' to ACORN. [source] Clinical trial: the treatment of gastro-oesophageal reflux disease in primary care , prospective randomized comparison of rabeprazole 20 mg with esomeprazole 20 and 40 mgALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 9 2009A. EGGLESTON Summary Background, A trial of empirical PPI therapy is usual practice for most patients with symptoms of gastro-oesophageal reflux disease (GERD) in primary care. Aim, To determine if the 4-week efficacy of rabeprazole 20 mg for resolving heartburn and regurgitation symptoms is non-inferior to esomeprazole 40 mg or 20 mg. Methods, In all, 1392 patients were randomized to rabeprazole 20 mg, esomeprazole 20 mg or 40 mg once daily. Patients, doctors and assessors were blinded. Symptom resolution data were collected on days 0,7 and day-28 using the Patient Assessment of Upper Gastrointestinal Disorders Symptom Severity Index with a shortened version used on days 8,27. Results, Rabeprazole 20 mg was non-inferior to esomeprazole 40 mg for complete resolution of regurgitation and satisfactory resolution of heartburn and regurgitation. For complete heartburn resolution, the efficacy of rabeprazole 20 mg and esomeprazole 40 mg was statistically indistinguishable, although the non-inferiority test was inconclusive. Rabeprazole 20 mg was non-inferior to esomeprazole 20 mg for all outcomes. Conclusions, In uninvestigated GERD patients, rabeprazole 20 mg was non-inferior to esomeprazole 40 mg for complete and satisfactory relief of regurgitation and satisfactory relief of heartburn, and not different for complete resolution of heartburn. [source] The global distribution of infant mortality: a subnational spatial viewPOPULATION, SPACE AND PLACE (PREVIOUSLY:-INT JOURNAL OF POPULATION GEOGRAPHY), Issue 3 2008Adam Storeygard Abstract We describe the compilation of a spatially explicit data-set detailing infant mortality rates in over 10,000 national and subnational units worldwide, benchmarked to the year 2000. Although their resolution is highly variable, subnational data are available for countries representing over 90% of the non-OECD population. Concentration of global infant deaths is higher than implied by national data alone. Assigning both national and subnational data to map grid cells so that they may be easily integrated with other geographical data, we generate infant mortality rates for environmental regions, including biomes and coastal zones, by continent. Rates for these regions also show striking refinements from the use of the higher resolution data. Possibilities and limitations for related work are discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination of molecular envelopes from solvent contrast variation dataACTA CRYSTALLOGRAPHICA SECTION A, Issue 4 2009Victor Lo An algorithm is described for determining macromolecular envelopes from crystal diffraction amplitudes measured from a solvent contrast variation series. The method uses solvent contrast variation data that have been preprocessed to represent the structure-factor amplitudes of the envelope. The amplitudes are phased using an iterative projection algorithm that incorporates connectivity and compactness constraints on the envelope. The algorithm is tested by simulation on two protein envelopes and shown to be effective even in the absence of the very low resolution data, which are difficult to access experimentally. [source] Clinical optical coherence tomography of early articular cartilage degeneration in patients with degenerative meniscal tearsARTHRITIS & RHEUMATISM, Issue 5 2010Constance R. Chu Objective Quantitative and nondestructive methods for clinical diagnosis and staging of articular cartilage degeneration are important to the evaluation of potential disease-modifying treatments in osteoarthritis (OA). Optical coherence tomography (OCT) is a novel imaging technology that can generate microscopic-resolution cross-sectional images of articular cartilage in near real-time. This study tested the hypotheses that OCT can be used clinically to identify early cartilage degeneration and that OCT findings correlate with magnetic resonance imaging (MRI) T2 values and arthroscopy results. Methods Patients undergoing arthroscopy for degenerative meniscal tears were recruited under Institutional Review Board,approved protocols. Thirty consecutive subjects completing preoperative 3.0T MRI, arthroscopy, and intraoperative OCT comprised the study group. Qualitative and quantitative OCT results and MRI T2 values were compared with modified Outerbridge cartilage degeneration scores (0,4 scale) assigned at arthroscopy. Results Arthroscopic grades showed cartilage abnormality in 23 of the 30 patients. OCT grades were abnormal in 28 of the 30 patients. Both qualitative and quantitative OCT strongly correlated with the arthroscopy results (P = 0.004 and P = 0.0002, respectively, by Kruskal-Wallis test). Neither the superficial nor the deep cartilage T2 values correlated with the arthroscopy results. The quantitative OCT results correlated with the T2 values in the superficial cartilage (Pearson's r = 0.39, P = 0.03). Conclusion These data show that OCT can be used clinically to provide qualitative and quantitative assessments of early articular cartilage degeneration that strongly correlate with arthroscopy results. The correlation between the quantitative OCT values and T2 values for the superficial cartilage further supports the utility of OCT as a clinical research tool, providing quantifiable microscopic resolution data on the articular cartilage structure. New technologies for nondestructive quantitative assessment of human articular cartilage degeneration may facilitate the development of strategies to delay or prevent the onset of OA. [source] Atomic resolution studies of carbonic anhydrase IIACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2010Craig A. Behnke Carbonic anhydrase has been well studied structurally and functionally owing to its importance in respiration. A large number of X-ray crystallographic structures of carbonic anhydrase and its inhibitor complexes have been determined, some at atomic resolution. Structure determination of a sulfonamide-containing inhibitor complex has been carried out and the structure was refined at 0.9,Å resolution with anisotropic atomic displacement parameters to an R value of 0.141. The structure is similar to those of other carbonic anhydrase complexes, with the inhibitor providing a fourth nonprotein ligand to the active-site zinc. Comparison of this structure with 13 other atomic resolution (higher than 1.25,Å) isomorphous carbonic anhydrase structures provides a view of the structural similarity and variability in a series of crystal structures. At the center of the protein the structures superpose very well. The metal complexes superpose (with only two exceptions) with standard deviations of 0.01,Å in some zinc,protein and zinc,ligand bond lengths. In contrast, regions of structural variability are found on the protein surface, possibly owing to flexibility and disorder in the individual structures, differences in the chemical and crystalline environments or the different approaches used by different investigators to model weak or complicated electron-density maps. These findings suggest that care must be taken in interpreting structural details on protein surfaces on the basis of individual X-ray structures, even if atomic resolution data are available. [source] MAD phasing using the (Ta6Br12)2+ cluster: a retrospective studyACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2008Oliwia Pasternak The crystal structure of cytokinin-specific binding protein (CSBP) containing four independent molecules with 4 × 155 = 620 residues in the asymmetric unit of the P64 unit cell has been solved by three-wavelength MAD using 1.8,Å resolution data recorded from a crystal derivatized with the dodecabromohexatantalum cation (Ta6Br12)2+. The diffraction data contained a very strong anomalous signal (allowing successful phasing even using peak SAD data alone) despite the fact that the five (Ta6Br12)2+ clusters found in the asymmetric unit have low occupancy (about 0.3). The derivative structure has been successfully refined to R = 0.158, providing interesting details on the geometry of the (Ta6Br12)2+ cluster, its interactions with the protein and on the backsoaking of a cytokinin ligand that was originally part of a CSBP,cytokinin complex in the native crystals used for (Ta6Br12)2+ derivatization. A simulation analysis of the phasing power of the (Ta6Br12)2+ ions at artificially imposed resolution limits shows that it is not possible to resolve the individual Ta atoms if the dmin limit of the data is higher than 2.9,Å. Additionally, for successful Ta identification the (Ta6Br12)2+ complex should be specifically bound and ordered. Good binding at the protein surface is facilitated by the presence of acidic groups, indicating higher pH buffer conditions to be preferable. In addition, the water channels in the crystal should be sufficiently wide (at least 11,Å) to allow free diffusion of the (Ta6Br12)2+ ions on soaking. A retrospective look at the initial molecular-replacement calculations provides interesting insights into how the peculiar packing mode and strong bias of the molecular-replacement-phased electron-density maps had hindered successful solution of the structure by this method. [source] High-resolution structure of a plasmid-encoded dihydrofolate reductase: pentagonal network of water molecules in the D2 -symmetric active siteACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2006Narendra Narayana R67 plasmid-encoded dihydrofolate reductase (R67 DHFR) is an NADPH-dependent homotetrameric enzyme that catalyzes the reduction of dihydrofolate to tetrahydrofolate. The amino-acid sequence and molecular architecture of R67 DHFR and its inhibitory properties toward folate analogues are different from those of chromosomal DHFR. Here, the crystal structure of R67 DHFR refined using 1.1,Å resolution data is presented. Blocked full-matrix least-squares refinement without restraints resulted in a final R factor of 11.4%. The anisotropic atomic displacement parameters analyzed by Rosenfield matrices and translation,libration,screw validation suggested four quasi-rigid domains. A total of ten C,,HO hydrogen bonds were identified between the ,-strands. There is reasonable structural evidence that His62 is not protonated in the tetramer, which is in accord with previous pH-profile studies. The side chain of Gln67 that protrudes into the active site exhibits dual conformation, a feature noticed for the first time owing to the availability of atomic resolution data. The R67 DHFR active site is unique: it has D2 symmetry and is a large active site with a pentagonal network of water molecules and exposure of backbone atoms to solvent; the central pore is favorable for planar ring-stacking interactions. The geometrical shape, overall symmetry, local asymmetry and waters appear to dominate the binding of ligands, catalysis and inhibition. [source] Structure of a yellow lupin pathogenesis-related PR-10 protein belonging to a novel subclassACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2005Oliwia Pasternak Pathogenesis-related (PR) proteins of class 10 are abundant in higher plants. Some of these proteins are induced under stress conditions as part of the plant defence mechanism. Other homologues are developmentally regulated and their expression varies in different plant organs. The PR-10 proteins are encoded by multigene families, have a weight of about 17,kDa and are found in the cytosol. In yellow lupin, nine different homologues have been identified and divided into two subclasses, LlPR-10.1 and LlPR-10.2. Within each subclass the sequence identity is about 75,91%, while across the subclasses it is only 59,60%. Here, the crystal structure of a yellow lupin PR-10 protein from the second subclass, LlPR-10.2A, is presented. The structure was solved by molecular replacement and refined to R = 0.205 using 1.9,Å resolution data. The general fold of LlPR-10.2A resembles that of the other PR-10 proteins and consists of a long C-terminal ,-helix surrounded by a seven-stranded antiparallel ,-sheet, with two shorter ,-helices located between strands ,1 and ,2. The most variable part of the structure, the C-terminal helix, is strongly kinked towards the ,-sheet core in both LlPR-10.2A molecules present in the asymmetric unit. This unexpected feature reduces the size of the hydrophobic cavity observed in other PR-10 proteins that is reported to be the ligand-binding site. As in other PR-10 structures, a surface loop located near the entrance to the cavity shows very high structural conservation and stability despite the high glycine content in its sequence. [source] Platinum-induced space-group transformation in crystals of the platelet glycoprotein Ib, N-terminal domainACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2004Kottayil I. Varughese The interaction between platelet glycoprotein (GP) Ib, and von Willebrand factor (VWF) is essential for thrombus formation, leading to the arrest of bleeding. The N-terminal domain of GP Ib,, which contains the binding sites for VWF and ,-thrombin, crystallized in the tetragonal space group P43 with one molecule in the asymmetric unit. When the crystals were treated with platinum, the crystals changed their symmetry from tetragonal to monoclinic P21 with two molecules in the asymmetric unit. The structure of the monoclinic form was solved using two-wavelength platinum anomalous dispersion data. The tetragonal crystal structure was subsequently solved using molecular-replacement techniques using the monoclinic structure as the search model and was refined with 1.7,Å resolution data. [source] Crystallization and preliminary crystallographic studies of a novel antifungal protein with five disulfide bridges from Eucommia ulmoides OliverACTA CRYSTALLOGRAPHICA SECTION D, Issue 10-2 2002Ye Xiang Two antifungal proteins, named Eucommia antifungal peptides 1 and 2 (EAFP1 and EAFP2), have been purified from the bark of the tree E. ulmoides Oliver and show a relatively broad spectrum of antifungal activity against several agriculturally important plant pathogens. One of these small proteins (EAFP2) has been crystallized. The crystal belongs to space group P21, with unit-cell parameters a = 19.01, b = 23.16, c = 30.69,Å, , = 98.54°. 1.0,Å resolution data were collected from an EAFP2 crystal and have been used to obtain phase information directly by an ab initio method. [source] Direct methods and protein crystallography at low resolutionACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2000Christopher J. Gilmore The tools of modern direct methods are examined and their limitations for solving protein structures discussed. Direct methods need atomic resolution data (1.1,1.2,Å) for structures of around 1000 atoms if no heavy atom is present. For low-resolution data, alternative approaches are necessary and these include maximum entropy, symbolic addition, Sayre's equation, group scattering factors and electron microscopy. [source] Crystallization and preliminary X-ray crystallographic analysis of Ca2+ -independent and Ca2+ -dependent species of the type II antifreeze proteinACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2006Yoshiyuki Nishimiya Ca2+ -independent and Ca2+ -dependent species of the type II antifreeze protein (AFP) were both crystallized using the hanging-drop vapour-diffusion method. It appeared that the crystal of the Ca2+ -independent species from Brachyosis rostratus belongs to space group P212121, with unit-cell parameters a = 43.3, b = 48.4, c = 59.7,Å, and diffraction data were collected to 1.34,Å resolution. For the Ca2+ -dependent type II AFP species from Hypomesus nipponensis, crystallization was carried out for its Ca2+ -free and Ca2+ -bound states. 1.25,Å resolution data were collected from the crystal in the Ca2+ -free state, which exhibited P3121 (or P3221) symmetry, with unit-cell parameters a = b = 66.0, c = 50.3,Å. Data collection could be extended to 1.06,Å resolution for the crystal in the Ca2+ -bound state, which appeared to be isomorphous to the crystal in the Ca2+ -free state (unit-cell parameters a = b = 66.0, c = 49.8,Å). These data will allow us to determine the high-resolution structures of the two species of type II AFP. [source] | |||||||||||||||||||