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Surface Maps (surface + map)
Selected AbstractsBridging the gap between field data and global models: current strategies in aeolian researchEARTH SURFACE PROCESSES AND LANDFORMS, Issue 4 2010Joanna Bullard Abstract Modern global models of earth-atmosphere-ocean processes are becoming increasingly sophisticated but still require validation against empirical data and observations. This commentary reports on international initiatives amongst aeolian researchers that seek to combine field-based data sets and geomorphological frameworks for improving the quality of data available to constrain and validate global models. These include a second iteration of the Dust Indicators and Records from Terrestrial Marine Palaeoenvironments (DIRTMAP2) database, the Digital Atlas of Sand Seas and Dunefields of the World and a new geomorphology-based land surface map produced by the QUEST (Quantifying Uncertainties in the Earth System) Working Group on Dust. Copyright © 2010 John Wiley & Sons, Ltd. [source] Structural MRI biomarkers for preclinical and mild Alzheimer's disease,HUMAN BRAIN MAPPING, Issue 10 2009Christine Fennema-Notestine Abstract Noninvasive MRI biomarkers for Alzheimer's disease (AD) may enable earlier clinical diagnosis and the monitoring of therapeutic effectiveness. To assess potential neuroimaging biomarkers, the Alzheimer's Disease Neuroimaging Initiative is following normal controls (NC) and individuals with mild cognitive impairment (MCI) or AD. We applied high-throughput image analyses procedures to these data to demonstrate the feasibility of detecting subtle structural changes in prodromal AD. Raw DICOM scans (139 NC, 175 MCI, and 84 AD) were downloaded for analysis. Volumetric segmentation and cortical surface reconstruction produced continuous cortical surface maps and region-of-interest (ROI) measures. The MCI cohort was subdivided into single- (SMCI) and multiple-domain MCI (MMCI) based on neuropsychological performance. Repeated measures analyses of covariance were used to examine group and hemispheric effects while controlling for age, sex, and, for volumetric measures, intracranial vault. ROI analyses showed group differences for ventricular, temporal, posterior and rostral anterior cingulate, posterior parietal, and frontal regions. SMCI and NC differed within temporal, rostral posterior cingulate, inferior parietal, precuneus, and caudal midfrontal regions. With MMCI and AD, greater differences were evident in these regions and additional frontal and retrosplenial cortices; evidence for non-AD pathology in MMCI also was suggested. Mesial temporal right-dominant asymmetries were evident and did not interact with diagnosis. Our findings demonstrate that high-throughput methods provide numerous measures to detect subtle effects of prodromal AD, suggesting early and later stages of the preclinical state in this cross-sectional sample. These methods will enable a more complete longitudinal characterization and allow us to identify changes that are predictive of conversion to AD. Hum Brain Mapp 2009. © 2009 Wiley-Liss, Inc. [source] Structures and energies of D -galactose and galabiose conformers as calculated by ab initio and semiempirical methodsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 7 2003Majda Rahal-Sekkal Abstract Optimized geometries and total energies of some conformers of ,- and ,- D -galactose have been calculated using the RHF/6-31G* ab initio method. Vibrational frequencies were computed at the 6-31G* level for the conformers that favor internal hydrogen bonding, in order to evaluate their enthalpies, entropies, Gibbs free energies, and then their structural stabilities. The semiempirical AM1, PM3, MNDO methods have also been performed on the conformers GG, GT, and TG of ,- and ,- D -galactose. In order to test the reliability of each semiempirical method, the obtained structures and energies from the AM1, PM3, and MNDO methods have been compared to those achieved using the RHF/6-31G* ab initio method. The MNDO method has not been investigated further, because of the large deviation in the structural parameters compared with those obtained by the ab initio method for the galactose. The semiempirical method that has yielded the best results is AM1, and it has been chosen to perform structural and energy calculations on the galabiose molecule (the disaccharides constituted by two galactose units , 1,4 linked). The goal of such calculations is to draw the energy surface maps for this disaccharide. To realize each map, 144 different possible conformations resulting from the rotations of the two torsional angles , and , of the glycosidic linkage are considered. In each calculation, at each increment of , and ,, using a step of 30° from 0 to 330°, the energy optimization is employed. In this article, we report also calculations concerning the galabiose molecule using different ab initio levels such as RHF/6-31G*, RHF/6-31G**, and B3Lyp/6-31G*. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 806,818, 2003 [source] Analysis of segregation process of n -alkanes in binary mixtures by FTIR and Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2005Andrzej Hacura Abstract In the FTIR and Raman spectroscopic studies, the phenomena of normal n -alkanes segregation in the binary mixtures of solid-state paraffin at room temperature were examined. Samples, in which one of the ingredients had been deuterated were prepared in different molar concentrations. Components of the mixture separated in time, creating separate domains, were observed in the changing of shape of infrared and Raman bands. The process of segregation depended on the difference of the chains' length of the mixture's ingredients and the molar fraction, in which the mixtures were prepared. The size of the created microdomains has been estimated based on the model describing shape and the splitting of the IR bands developed by Hiebert and Hornig. By applying the micro-Raman imaging technique, a number of surface maps have been obtained indicating the separating process of ingredients of the mixtures. This allowed comparing and verifying time dependent results of the IR study. Copyright © 2005 John Wiley & Sons, Ltd. [source] Inferring X-ray coronal structures from Zeeman,Doppler imagesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2002M. Jardine Abstract We have modelled the X-ray emission from the young rapid rotator AB Doradus (Prot= 0.514 d) using as a basis Zeeman,Doppler maps of the surface magnetic field. This allows us to reconcile the apparently conflicting observations of a high X-ray emission measure and coronal density with a low rotational modulation in the X-ray band. The technique is to extrapolate the coronal field from the surface maps by assuming the field to be potential. We then determine the coronal density for an isothermal corona by solving hydrostatic equilibrium along each field line and scaling the surface plasma pressure with the surface magnetic pressure. We set the density to zero along those field lines that are open and those where at any point along their length the plasma pressure exceeds the magnetic pressure. We then calculate the optically thin X-ray emission measure and rotational modulation for models with a range of coronal densities. Although the corona can be very extended, much of the emission comes from high-latitude regions close to the stellar surface. Since these are always in view as the star rotates, there is little rotational modulation. We find that emission measures in the observed range 1052.8,1053.3 cm,3 can be reproduced with densities in the range 109,1010.7 cm,3 for coronae at temperatures of 106,107 K. [source] Characterisation and cleaning of oxide support materials for cavity ring-down spectroscopyPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2010Aras Kartouzian Abstract Cavity ring-down spectroscopy (CRDS) has been applied to characterise different oxide materials (amorphous silica, borosilicate and yttria stabilised zirconia YSZ) which are suitable to be used as support material for size-selected metal clusters. The sensitivity of the spectroscopic method was improved by means of transversal mode matching and spatial filtering of the laser beam profile, reducing the relative error by 50%. The high sensitivity of CRDS allows the detection of trace amounts of impurities and defect sites in the samples, based on their absorption properties. In YSZ, traces of Nd have been detected. The optical quality of the substrates was determined qualitatively according to the measured optical losses. CRDS surface maps have been used to monitor the homogeneity of the support materials, and the influence of ion bombardment on the surface has been studied. It is shown that in the case of BK7® substrates, sputtering with low energy Ar+ ions could remove deposited gold clusters almost completely causing very low damage to the surface. These results were confirmed analytically. [source] Three-dimensional surface maps link local atrophy and fast ripples in human epileptic hippocampus,ANNALS OF NEUROLOGY, Issue 6 2009Jennifer A. Ogren PhD Objectives There is compelling evidence that pathological high-frequency oscillations (HFOs), called fast ripples (FR, 150,500Hz), reflect abnormal synchronous neuronal discharges in areas responsible for seizure genesis in patients with mesial temporal lobe epilepsy (MTLE). It is hypothesized that morphological changes associated with hippocampal atrophy (HA) contribute to the generation of FR, yet there is limited evidence that hippocampal FR-generating sites correspond with local areas of atrophy. Methods Interictal HFOs were recorded from hippocampal microelectrodes in 10 patients with MTLE. Rates of FR and ripple discharge from each microelectrode were evaluated in relation to local measures of HA obtained using 3-dimensional magnetic resonance imaging (MRI) hippocampal modeling. Results Rates of FR discharge were 3 times higher in areas of significant local HA compared with rates in nonatrophic areas. Furthermore, FR occurrence correlated directly with the severity of damage in these local atrophic regions. In contrast, we found no difference in rates of ripple discharge between local atrophic and nonatrophic areas. Interpretation The proximity between local HA and microelectrode-recorded FR suggests that morphological changes such as neuron loss and synaptic reorganization may contribute to the generation of FR. Pathological HFOs, such as FR, may provide a reliable surrogate marker of abnormal neuronal excitability in hippocampal areas responsible for the generation of spontaneous seizures in patients with MTLE. Based on these data, it is possible that MRI-based measures of local HA could identify FR-generating regions, and thus provide a noninvasive means to localize epileptogenic regions in hippocampus. Ann Neurol 2009;66:783,791 [source] | |||||||||||||