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  • 1
    Language: English
    In: Journal of the American Chemical Society, 18 January 2012, Vol.134(2), pp.1344-51
    Description: Various 2-thienyllithium derivatives were investigated in the solid state by X-ray diffraction and in solution by 2D NMR experiments. The determined structures of [(Et(2)O)Li(C(4)H(3)S)](4) (1), [(THF)(2)Li(C(4)H(3)S)](2) (2), [(DME)Li(C(4)H(3)S)](2) (3), [(TMEDA)Li(C(4)H(3)S)](2) (4), and [(PMDETA)Li(C(4)H(3)S)] (5) (DME = 1,2-dimethoxyethane, TMEDA = N,N,N',N'-tetramethylethylene-1,2-diamine, and PMDETA = N,N,N',N",N"-pentamethyldiethylenetriamine) were solved in nondonating toluene and provide firm ground for diffusion-ordered NMR spectroscopy as well as heteronuclear Overhauser enhancement NMR spectroscopy. The distance relation of nuclear Overhauser effects with a factor of r(-6) is employed to gain further insight into the aggregation degree of 1-5 in solution. Comparison of the slope provided by the linear region of the buildup curves and of the ∑r(-6) calculated distances from the crystal structures offers a handle to judge the structure retention versus conversion in solution. The structures of 3-5 are maintained in toluene solution. The data of 2, however, indicate a partial dissociation or a rapid exchange between the vertices of a tetrameric core and free THF molecules. Auxiliary exchange spectroscopy investigations showed that the signals of the nitrogen donor base containing compounds 4 and 5 exchange with the signals of nonlithiated thiophene. This is explained by exchange of the deuterium by a hydrogen atom via lithiation of toluene molecules.
    Keywords: Dissociation Reactions -- Analysis ; Lithium Compounds -- Structure ; Lithium Compounds -- Chemical Properties ; Nuclear Magnetic Resonance Spectroscopy -- Usage ; Thiophene -- Structure ; Thiophene -- Chemical Properties ; Toluene -- Chemical Properties;
    ISSN: 00027863
    E-ISSN: 1520-5126
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  • 2
    Language: English
    In: Neuroimage, July 15, 2013, Vol.75, p.1(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.neuroimage.2013.02.039 Byline: Pierre LeVan, Julian Maclaren, Michael Herbst, Rebecca Sostheim, Maxim Zaitsev, Jurgen Hennig Abstract: The combination of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) allows the investigation of neuronal activity with high temporal and spatial resolution. While much progress has been made to overcome the multiple technical challenges associated with the recording of EEG inside the MR scanner, the ballistocardiographic (BCG) artifact, which is caused by cardiac-related motion inside the magnetic field, remains a major issue affecting EEG quality. The BCG is difficult to remove by standard average artifact subtraction (AAS) methods due to its variability across cardiac cycles. We thus investigate the possibility of directly recording the BCG motion using an optical motion-tracking system. In 5 subjects, the system is shown to accurately measure BCG motion. Regressing out linear and quadratic functions of the measured motion parameters resulted in a significant reduction (p〈0.05) in root-mean-square (RMS) amplitudes across cardiac cycles compared to AAS. A further significant RMS reduction was obtained when applying the regression and AAS methods sequentially, resulting in RMS amplitudes that were not significantly different from those of EEG recorded outside the scanner, although with higher residual variability. The large contributions of pure translational parameters and of non-linear terms to the BCG waveforms indicate that non-rigid motion of the EEG wires (originating from rigid head motion) is likely an important cause of the artifact. Article History: Accepted 14 February 2013
    Keywords: Electroencephalography ; Magnetic Resonance Imaging
    ISSN: 1053-8119
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: The Journal of Chemical Physics, 28 August 2018, Vol.149(8)
    Description: We present the design of a flexible quantum-chemical method development framework, which supports employing any type of basis function. This design has been implemented in the light-weight program package molsturm , yielding a basis-function-independent self-consistent field scheme. Versatile interfaces, making use of open standards like python , mediate the integration of molsturm with existing third-party packages. In this way, both rapid extension of the present set of methods for electronic structure calculations as well as adding new basis function types can be readily achieved. This makes molsturm well-suitable for testing novel approaches for discretising the electronic wave function and allows comparing them to existing methods using the same software stack. This is illustrated by two examples, an implementation of coupled-cluster doubles as well as a gradient-free geometry optimisation, where in both cases, arbitrary basis functions could be used. molsturm is open-sourced and can be obtained from http://molsturm.org .
    Keywords: Articles
    ISSN: 0021-9606
    E-ISSN: 1089-7690
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  • 4
    Language: English
    In: Applied and Environmental Microbiology, April 15, 2013, Vol.79(8), pp.2572-6
    Keywords: Lysimetry – Usage ; Mycobacteria – Research ; Mycobacteria – Physiological Aspects ; Sulfadiazine – Research
    ISSN: 0099-2240
    Source: Cengage Learning, Inc.
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  • 5
    Language: English
    In: Morningstar FundInvestor, Feb, 2014, Vol.22(6), p.8-9
    Keywords: Investment Companies -- Officials And Employees ; Mutual Fund Industry -- Officials And Employees ; Securities Industry -- Officials And Employees ; Artisan Funds ; Morgan Stanley ; Pacific Investment Management L.L.C.
    ISSN: 1099-0402
    Source: Cengage Learning, Inc.
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  • 6
    Article
    Article
    Language: English
    In: Morningstar FundInvestor, July, 2011, Vol.19(11), p.8-9
    Keywords: Emerging Markets -- Forecasts And Trends ; Mutual Fund Industry -- Securities ; Mutual Fund Industry -- Investor Relations ; Mutual Funds -- Evaluation ; Mutual Funds -- Forecasts And Trends ; Securities Analysis
    ISSN: 1099-0402
    Source: Cengage Learning, Inc.
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  • 7
    Language: English
    In: NeuroImage, 15 August 2017, Vol.157, pp.660-674
    Description: Rapid whole-brain dynamic Magnetic Resonance Imaging (MRI) is of particular interest in Blood Oxygen Level Dependent (BOLD) functional MRI (fMRI). Faster acquisitions with higher temporal sampling of the BOLD time-course provide several advantages including increased sensitivity in detecting functional activation, the possibility of filtering out physiological noise for improving temporal SNR, and freezing out head motion. Generally, faster acquisitions require undersampling of the data which results in aliasing artifacts in the object domain. A recently developed low-rank ( ) plus sparse ( ) matrix decomposition model (L+S) is one of the methods that has been introduced to reconstruct images from undersampled dynamic MRI data. The L+S approach assumes that the dynamic MRI data, represented as a space-time matrix , is a linear superposition of and components, where represents highly spatially and temporally correlated elements, such as the image background, while captures dynamic information that is sparse in an appropriate transform domain. This suggests that L+S might be suited for undersampled task or slow event-related fMRI acquisitions because the periodic nature of the BOLD signal is sparse in the temporal Fourier transform domain and slowly varying low-rank brain background signals, such as physiological noise and drift, will be predominantly low-rank. In this work, as a proof of concept, we exploit the L+S method for accelerating block-design fMRI using a 3D stack of spirals (SoS) acquisition where undersampling is performed in the domain. We examined the feasibility of the L+S method to accurately separate temporally correlated brain background information in the component while capturing periodic BOLD signals in the component. We present results acquired in control human volunteers at 3 T for both retrospective and prospectively acquired fMRI data for a visual activation block-design task. We show that a SoS fMRI acquisition with an acceleration of four and L+S reconstruction can achieve a brain coverage of 40 slices at 2 mm isotropic resolution and 64 x 64 matrix size every 500 ms.
    Keywords: Low Rank Plus Sparse Modeling ; Brain Functional Imaging ; Spiral Sampling ; Medicine
    ISSN: 1053-8119
    E-ISSN: 1095-9572
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  • 8
    Language: English
    In: Journal of Hydrology, Feb 25, 2013, Vol.481, p.106(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2012.12.024 Byline: Gonzalo Martinez (a)(b), Yakov A. Pachepsky (b), Harry Vereecken (c), Horst Hardelauf (c), Michael Herbst (c), Karl Vanderlinden (d) Keywords: Soil water content; Temporal stability; Simulations; Local controls; Saturated hydraulic conductivity Abstract: a* We simulated soil water flow in bare and grassed soil columns of three textures. a* Typical features of soil water temporal stability were recovered in simulations. a* Simulated duration and season affected the temporal stability of soil water contents. a* Spatio-temporal variations in soil water correlated with soil hydraulic conductivity. Author Affiliation: (a) Dept. of Agronomy, University of Cordoba, 14071 Cordoba, Spain (b) USDA-ARS- Environmental Microbial and Food Safety Lab, Beltsville, MD 20705, USA (c) Agrosphere (IBG-3), Institute of Bio- and Geosciences, Forschungszentrum Julich GmbH, 52428 Julich, Germany (d) IFAPA, Centro Las Torres-Tomejil, 41200 Alcala del Rio, Spain Article History: Received 15 December 2011; Revised 14 December 2012; Accepted 17 December 2012 Article Note: (miscellaneous) This manuscript was handled by Corrado Corradini, Editor-in-Chief, with the assistance of Axel Bronstert, Associate Editor
    Keywords: Hydrogeology -- Models ; Food Safety -- Models ; Soil Moisture -- Models ; Hydraulic Flow -- Models ; Water -- Models
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 9
    Language: English
    In: Water Research, March 1, 2014, Vol.50, p.294(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.watres.2013.10.032 Byline: David Vonberg, Jan Vanderborght, Nils Cremer, Thomas Putz, Michael Herbst, Harry Vereecken Abstract: Atrazine was banned in Germany in 1991 due to findings of atrazine concentrations in ground- and drinking waters exceeding threshold values. Monitoring of atrazine concentrations in the groundwater since then provides information about the resilience of the groundwater quality to changing agricultural practices. In this study, we present results of a monitoring campaign of atrazine concentrations in the Zwischenscholle aquifer. This phreatic aquifer is exposed to intensive agricultural land use and susceptible to contaminants due to a shallow water table. In total 60 observation wells (OWs) have been monitored since 1991, of which 15 are sampled monthly today. Descriptive statistics of monitoring data were derived using the "regression on order statistics" (ROS) data censoring approach, estimating values for nondetects. The monitoring data shows that even 20 years after the ban of atrazine, the groundwater concentrations of sampled OWs remain on a level close to the threshold value of 0.1 [mu]g l.sup.-1 without any considerable decrease. The spatial distribution of atrazine concentrations is highly heterogeneous with OWs exhibiting permanently concentrations above the regulatory threshold on the one hand and OWs were concentrations are mostly below the limit of quantification (LOQ) on the other hand. A deethylatrazine-to-atrazine ratio (DAR) was used to distinguish between diffuse - and point-source contamination, with a global mean value of 0.84 indicating mainly diffuse contamination. Principle Component Analysis (PCA) of the monitoring dataset demonstrated relationships between the metabolite desisopropylatrazine, which was found to be exclusively associated with the parent compound simazine but not with atrazine, and between deethylatrazine, atrazine, nitrate, and the specific electrical conductivity. These parameters indicate agricultural impacts on groundwater quality. The findings presented in this study point at the difficulty to estimate mean concentrations of contamination for entire aquifers and to evaluate groundwater quality based on average parameters. However, analytical data of monthly sampled single observation wells provide adequate information to characterize local contamination and evolutionary trends of pollutant concentration. Author Affiliation: (a) Agrosphere Institute (IBG-3), Forschungszentrum Julich GmbH, 52425 Julich, Germany (b) Erftverband, Am Erftverband 6, 50126 Bergheim, Germany Article History: Received 7 May 2013; Revised 6 September 2013; Accepted 14 October 2013
    Keywords: Aquifers -- Analysis ; Aquifers -- Electric Properties ; Metabolites -- Analysis ; Metabolites -- Electric Properties ; Atrazine -- Analysis ; Atrazine -- Electric Properties ; Electrical Conductivity -- Analysis ; Electrical Conductivity -- Electric Properties ; Groundwater -- Analysis ; Groundwater -- Electric Properties
    ISSN: 0043-1354
    Source: Cengage Learning, Inc.
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  • 10
    Language: German
    In: Pastoraltheologie, 01/2017, Vol.106(1), pp.6-12
    Description: Abstract A vital church featuring a “mixed” economy of parishes and fresh expressions of church provides the basis for a pastoral vision less pressured by unrealistic demands on the minister and more related to volunteers.
    Keywords: Religion;
    ISSN: 0720-6259
    E-ISSN: 2197-0831
    Source: CrossRef
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