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Hierarchical Scheme (hierarchical + scheme)
Selected AbstractsHierarchical scheme for liquid chromatography/multi-stage spectrometric identification of 3,4,5-triacyl chlorogenic acids in green Robusta coffee beansRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 15 2010Rakesh Jaiswal Liquid chromatography/multi-stage spectrometry (LC/MSn) (n,=,2,4) has been used to detect and characterize in green Robusta coffee beans eight quantitatively minor triacyl chlorogenic acids with seven of them not previously reported in nature. These comprise 3,4,5-tricaffeoylquinic acid (Mr 678); 3,5-dicaffeoyl-4-feruloylquinic acid, 3-feruloyl-4,5-dicaffeoylquinic acid and 3,4-dicaffeoyl-5-feruloylquinic acid (Mr 692); 3-caffeoyl-4,5-diferuloylquinic acid and 3,4-diferuloyl-5 - caffeoylquinic acid (Mr 706); and 3,4-dicaffeoyl-5-sinapoylquinic acid and 3-sinapoyl-4,5-dicaffeoylquinic acid (Mr 722). Structures have been assigned on the basis of LC/MSn patterns of fragmentation. A new hierarchical key for the identification of triacyl quinic acids is presented, based on previously established rules of fragmentation. Fifty-two chlorogenic acids have now been characterized in green Robusta coffee beans. In this study five samples of green Robusta coffee beans and fifteen samples of Arabica coffee beans were analyzed with triacyl chlorogenic acids only found in Robusta coffee bean extracts. These triacyl chlorogenic acids could be considered as useful phytochemical markers for the identification of Robusta coffee beans. Copyright © 2010 John Wiley & Sons, Ltd. [source] Dual-level hierarchical scheme for linear-scaling divide-and-conquer correlation theory,INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 10 2009Masato Kobayashi Abstract A dual-level hierarchical scheme for the linear-scaling divide-and-conquer (DC)-based correlation theory is presented as a combination of dual-buffer and dual-basis approaches. Although the dual-basis approach has been well developed, the dual-buffer approach is specific for the DC correlation method and based on the different interaction lengths between the Hartree,Fock and correlation methods. This study performs numerical assessments of the dual-buffer DC-MP2 (second-order Møller,Plesset perturbation) systematically. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Thalamic label patterns suggest primary and ventral auditory fields are distinct core regionsTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 10 2010Douglas A. Storace Abstract A hierarchical scheme proposed by Kaas and colleagues suggests that primate auditory cortex can be divided into core and belt regions based on anatomic connections with thalamus and distinctions among response properties. According to their model, core auditory cortex receives predominantly unimodal sensory input from the ventral nucleus of the medial geniculate body (MGBv); whereas belt cortex receives predominantly cross-modal sensory input from nuclei outside the MGBv. We previously characterized distinct response properties in rat primary (A1) versus ventral auditory field (VAF) cortex; however, it has been unclear whether VAF should be categorized as a core or belt auditory cortex. The current study employed high-resolution functional imaging to map intrinsic metabolic responses to tones and to guide retrograde tracer injections into A1 and VAF. The size and density of retrogradely labeled somas in the medial geniculate body (MGB) were examined as a function of their position along the caudal-to-rostral axis, subdivision of origin, and cortical projection target. A1 and VAF projecting neurons were found in the same subdivisions of the MGB but in rostral and caudal parts, respectively. Less than 3% of the cells projected to both regions. VAF projecting neurons were smaller than A1 projecting neurons located in dorsal (MGBd) and suprageniculate (SG) nuclei. Thus, soma size varied with both caudal-rostral position and cortical target. Finally, the majority (>70%) of A1 and VAF projecting neurons were located in MGBv. These MGB connection profiles suggest that rat auditory cortex, like primate auditory cortex, is made up of multiple distinct core regions. J. Comp. Neurol. 518:1630,1646, 2010. © 2010 Wiley-Liss, Inc. [source] Structures of the ZrZn22 family: suprapolyhedral nanoclusters, methods of self-assembly and superstructural orderingACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2009G. D. Ilyushin A combinatorial topological analysis is carried out by means of the program package TOPOS4.0 [Blatov (2006), IUCr Comput. Commun. Newsl.7, 4,38] and the matrix self-assembly is modeled for crystal structures of the ZrZn22 family (space group , Pearson code cF184), including the compounds with superstructural ordering. A number of strict rules are proposed to model the crystal structures of intermetallics as a network of cluster precursors. According to these rules the self-assembly of the ZrZn22 -like structures was considered within the hierarchical scheme: primary polyhedral cluster , zero-dimensional nanocluster precursor , one-dimensional primary chain , two-dimensional microlayer , three-dimensional microframework (three-dimensional supraprecursor). The suprapolyhedral cluster precursor AB2X37 of diameter ,,12,Å and volume ,,350,Å3 consists of three polyhedra (one AX16 of the point symmetry and two regular icosahedra BX12 of the point symmetry); the packing of the clusters determines the translations in the resulting crystal structure. A novel topological type of the two-dimensional crystal-forming 4,4-coordinated binodal net AB2, with the Schläfli symbols 3636 and 3366 for nodes A and B, is discovered. It is shown that the ZrZn22 superstructures are formed by substituting some atoms in the cluster precursors. Computer analysis of the CRYSTMET and ICSD databases shows that the cluster AB2X37 occurs in 111 intermetallics belonging to 28 structure types. [source] Effect of mate selection on fuzzy selective mating criteria in closed dairy multiple ovulation and embryo transfer nucleus programsANIMAL SCIENCE JOURNAL, Issue 3 2002Atsushi NAKAMURA ABSTRACT In order to control rates of response and inbreeding, mate selection using fuzzy selective mating criteria (FMC) was investigated in adult multiple ovulation and embryo transfer nucleus schemes for dairy cattle. Stochastic simulation was used to model the closed nucleus scheme. This mate selection was examined in four alternative mating and male selection schemes: (i) a hierarchical scheme; (ii) a hierarchical sibship scheme (two males per sibship); (iii) a factorial scheme (two sires per dam); and (iv) a factorial sibship scheme (two males per sibship and two sires per dam). Genetic response and inbreeding rate tended to be reduced by increasing the trade-off parameter of FMC between the expected breeding value and inbreeding of progeny. Inbreeding rates in all schemes were reduced by reducing the variance of family size through selection and the average coancestry of mating pairs through mate allocation. [source] Modelling species distributions in Britain: a hierarchical integration of climate and land-cover dataECOGRAPHY, Issue 3 2004Richard G. Pearson A modelling framework for studying the combined effects of climate and land-cover changes on the distribution of species is presented. The model integrates land-cover data into a correlative bioclimatic model in a scale-dependent hierarchical manner, whereby Artificial Neural Networks are used to characterise species' climatic requirements at the European scale and land-cover requirements at the British scale. The model has been tested against an alternative non-hierarchical approach and has been applied to four plant species in Britain: Rhynchospora alba, Erica tetralix, Salix herbacea and Geranium sylvaticum. Predictive performance has been evaluated using Cohen's Kappa statistic and the area under the Receiver Operating Characteristic curve, and a novel approach to identifying thresholds of occurrence which utilises three levels of confidence has been applied. Results demonstrate reasonable to good predictive performance for each species, with the main patterns of distribution simulated at both 10 km and 1 km resolutions. The incorporation of land-cover data was found to significantly improve purely climate-driven predictions for R. alba and E. tetralix, enabling regions with suitable climate but unsuitable land-cover to be identified. The study thus provides an insight into the roles of climate and land-cover as determinants of species' distributions and it is demonstrated that the modelling approach presented can provide a useful framework for making predictions of distributions under scenarios of changing climate and land-cover type. The paper confirms the potential utility of multi-scale approaches for understanding environmental limitations to species' distributions, and demonstrates that the search for environmental correlates with species' distributions must be addressed at an appropriate spatial scale. Our study contributes to the mounting evidence that hierarchical schemes are characteristic of ecological systems. [source] | |||||||||||||