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  • Wiley Online Library  (12)
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  • 1
    In: AIChE Journal, August 2019, Vol.65(8), pp.n/a-n/a
    Description: Liquid maldistribution is one of the main deficiencies in random packed column design. Therefore, the knowledge of liquid distribution and its model‐based prediction is of great interest. This work aims to further develop and validate the TUM–WelChem Cell Model for random packed columns. First, cell dimension calculations and the determination of random packing element orientations are standardized. The original WelChem Cell Model applies a liquid distribution mechanism based on liquid spread factors derived by virtual 3D irrigation experiments. An extension of the model involves the implementation of liquid and gas load related distribution mechanisms, considering dispersion effects caused by liquid loading and the countercurrent gas flow. The wall flow is refined by an increase of packing porosity at the column wall. Liquid distribution profiles provided by the TUM–WelChem Cell Model are validated against experimental data and show good agreement for both uniform and point source initial liquid distribution.
    Keywords: Cell Model ; Liquid Distribution ; Maldistribution ; Packed Column ; Random Packing
    ISSN: 0001-1541
    E-ISSN: 1547-5905
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  • 2
    Language: English
    In: Advanced Materials, 08 December 2011, Vol.23(46), pp.5568-5573
    Description: Exchange‐biased samples with designed stripe‐domains show strong stray fields and an asymmetric magnetization reversal. Using these characteristics superparamagnetic particles can be trapped and transported directly on the sample over large‐scale areas. High particle velocities, small external fields, and automatically reduced particle clustering allow broad applicability of this transport method.
    Keywords: Magnetic Nanoparticles ; Thin Films ; Magnetic Materials ; Microstructures
    ISSN: 0935-9648
    E-ISSN: 1521-4095
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  • 3
    In: European Journal of Neuroscience, December 2018, Vol.48(12), pp.3583-3596
    Description: Synchronous spiking of multiple neurons is a key phenomenon in normal brain function and pathologies. Recently, approaches to record spikes from the intact cortical surface using small high‐density arrays of microelectrodes have been reported. It remained unaddressed how epicortical spiking relates to intracortical unit activity. We introduced a mesoscale approach using an array of 64 electrodes with intermediate diameter (250 μm) and combined large‐coverage epicortical recordings in ferrets with intracortical recordings via laminar probes. Empirical data and modelling strongly suggest that our epicortical electrodes selectively captured synchronized spiking of neurons in the cortex beneath. As a result, responses to sensory stimulation were more robust and less noisy compared to intracortical activity, and receptive field properties were well preserved in epicortical recordings. This should promote insights into assembly‐coding beyond the informative value of subdural EEG or single‐unit spiking, and be advantageous to real‐time applications in brain‐machine interfacing. We have compared spiking activity in simultaneous recordings from layers and the intact surface (ECoG) of sensory cortices in the ferret brain. Surface spiking reflected the truly representative activity of the cortical column, i.e. spikes fired in synchrony by several units. We show that this can sharpen tuning, reduce response variability and thus make single trial surface spiking data as informative as post hoc analyzed multi trial or population data from intracortical multi site recordings.
    Keywords: Assembly‐Coding ; Auditory Cortex ; Brain‐Machine Interfaces ; Electrocorticography ; Synchronous Spiking ; Visual Cortex
    ISSN: 0953-816X
    E-ISSN: 1460-9568
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  • 4
    In: European Journal of Neuroscience, May 2015, Vol.41(10), pp.1311-1320
    Description: The integration of visual and auditory spatial information is important for building an accurate perception of the external world, but the fundamental mechanisms governing such audiovisual interaction have only partially been resolved. The earliest interface between auditory and visual processing pathways is in the midbrain, where the superior () and inferior colliculi () are reciprocally connected in an audiovisual loop. Here, we investigate the mechanisms of audiovisual interaction in the midbrain by recording neural signals from the and simultaneously in anesthetized ferrets. Visual stimuli reliably produced band‐limited phase locking of local field potentials (s) in two distinct frequency bands: 6–10 and 15–30 Hz. These visual responses co‐localized with robust auditory responses that were characteristic of the . Imaginary coherence analysis confirmed that visual responses in the were not volume‐conducted signals from the neighboring . Visual responses in the occurred later than retinally driven superficial layers and earlier than deep layers that receive indirect visual inputs, suggesting that retinal inputs do not drive visually evoked responses in the . In addition, and recording sites with overlapping visual spatial receptive fields displayed stronger functional connectivity than sites with separate receptive fields, indicating that visual spatial maps are aligned across both midbrain structures. Reciprocal coupling between the and therefore probably serves the dynamic integration of visual and auditory representations of space. The earliest interface between auditory and visual processing pathways is in the midbrain, where the superior (SC) and inferior colliculi (IC) are reciprocally connected in an audiovisual loop. Here, we show that visual stimuli elicit phase locking in IC local field potentials, and that the timing of responses across the midbrain suggests the SC as a possible source of visually‐evoked entrainment in the IC.
    Keywords: Auditory ; Ferret ; Local Field Potential ; Midbrain ; Visual
    ISSN: 0953-816X
    E-ISSN: 1460-9568
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  • 5
    Language: English
    In: ChemCatChem, February 2015, Vol.7(3), pp.490-500
    Description: Even though there is an urgent need for new antifungals with improved clinical properties, the substrate promiscuity of tailoring enzymes has been poorly studied as a source of new structural diversity for polyene macrolides. We explore the acceptance of different polyene macrolides by the glutamine amidotransferase PscA and the catalytic effect of different homologous P450 cytochromes on a common scaffold, the pimaricin precursor 4,5‐desepoxypimaricin. By combining these two parallel strategies, we present three new pimaricin derivatives and a new lucensomycin variant. Our results show that P450 cytochromes devoted to the modification of the polyol region of polyene macrolides are not as substrate‐specific as previously thought and highlight PscA as a versatile small‐ring polyene‐modifying enzyme that allows the preparation of new carboxamide derivatives. We also provide useful information for the future production of previously unconceived epoxidized polyene macrolide antifungals. The substrate promiscuity of two groups of biosynthetic tailoring enzymes opens up new perspectives for the creation of new valuable polyene macrolide antifungals. New hydroxylated and carboxamidated derivatives are described and possible epoxidations suggested.
    Keywords: Antibiotics ; Antifungal Agents ; Chemical Diversity ; Natural Products ; P450 Cytochromes
    ISSN: 1867-3880
    E-ISSN: 1867-3899
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  • 6
    In: Advanced Functional Materials, November 2015, Vol.25(43), pp.6768-6774
    Description: A new approach for aligning wrinkles in thin viscoelastic polymethylmethacrylate films is established by sandwiching them between ferromagnetic layers. Experiments prove that a contribution from an engineered anisotropic 1D periodic magnetic stray field pattern can be decisive for the alignment of otherwise randomly oriented wrinkles at commensurate periods of the magnetic template pattern and the wrinkles. Alternatively, random wrinkling is observed under similar conditions, but when periodic magnetic stray fields are missing or not commensurate with the wrinkle wavelength. The possibility to stabilize two distinct types of wrinkling patterns in the same material system paves the way toward mechanically reconfigurable functional elements, enabling exciting possibilities for stretchable electronics, magnetic field sensors, and tuneable gratings for optoelectronics and photonics. is presented. By the interaction of a ferromagnetic thin film with a tailored micromagnetic stray field pattern the systems entropy can be influenced as shown by proof of principle experiments. Using additional external magnetic stimuli this method allows switchable wrinkle systems.
    Keywords: Alignment ; Magnetic Stray Fields ; Magnetic Thin Films ; Self‐Organization ; Wrinkling
    ISSN: 1616-301X
    E-ISSN: 1616-3028
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  • 7
    In: Bipolar Disorders, December 2008, Vol.10(8), pp.877-887
    Description: There is growing evidence of cognitive impairment as a trait factor in bipolar disorder. The generalizability of this finding is limited because previous studies have either focussed exclusively on bipolar I disorder or have analysed mixed patient groups. Thus, it is still largely unknown whether bipolar II patients perform differently from bipolar I patients on measures of cognitive functioning. A total of 65 patients with bipolar I disorder, 38 with bipolar II disorder, and 62 healthy controls participated in the study. Patients had to be euthymic for at least one month. Clinical and demographic variables were collected in a clinical interview and with the Structured Clinical Interview for DSM‐IV. Cognitive functioning was assessed using a neuropsychological battery. Univariate and multivariate analyses of variance were conducted for analyzing possible differences between the groups. The multivariate analysis of covariance (MANCOVA) indicated overall differences in neuropsychological performance between the three groups (Pillai Spur: 1.96, p = 0.003). Post hoc comparisons revealed that patients with bipolar I disorder showed significantly lower scores in psychomotor speed, working memory, verbal learning, delayed memory, and executive functions than healthy controls. Patients with bipolar II disorder showed significant deficits in psychomotor speed, working memory, visual/constructional abilities, and executive functions compared to controls, but not on verbal learning and delayed memory. The two patient groups did not differ significantly from each other on any domain tested. These results support a similar pattern of cognitive deficits in both subtypes of bipolar disorder.
    Keywords: Bipolar I Disorder ; Bipolar Ii Disorder ; Cognition ; Neuropsychological Functioning
    ISSN: 1398-5647
    E-ISSN: 1399-5618
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  • 8
    In: Molecular Ecology, May 2019, Vol.28(9), pp.2224-2237
    Description: Bacteria that engage in long‐standing associations with particular hosts are expected to evolve host‐specific adaptations that limit their capacity to thrive in other environments. Consistent with this, many gut symbionts seem to have a limited host range, based on community profiling and phylogenomics. However, few studies have experimentally investigated host specialization of gut symbionts and the underlying mechanisms have largely remained elusive. Here, we studied host specialization of a dominant gut symbiont of social bees, Firm5. We show that Firm5 strains isolated from honey bees and bumble bees separate into deep‐branching host‐specific phylogenetic lineages. Despite their divergent evolution, colonization experiments show that bumble bee strains are capable of colonizing the honey bee gut. However, they were less successful than honey bee strains, and competition with honey bee strains completely abolished their colonization. In contrast, honey bee strains of divergent phylogenetic lineages were able to coexist within individual bees. This suggests that both host selection and interbacterial competition play important roles in host specialization. Using comparative genomics of 27 Firm5 isolates, we found that the genomes of honey bee strains harbour more carbohydrate‐related functions than bumble bee strains, possibly providing a competitive advantage in the honey bee gut. Remarkably, most of the genes encoding carbohydrate‐related functions were not conserved among the honey bee strains, which suggests that honey bees can support a metabolically more diverse community of Firm5 strains than bumble bees. These findings advance our understanding of the genomic changes underlying host specialization.
    Keywords: Adaptation ; Bioinformatics/Phyloinformatics ; Community Ecology ; Genomics/Proteomics ; Microbial Biology ; Molecular Evolution
    ISSN: 0962-1083
    E-ISSN: 1365-294X
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  • 9
    In: Biotropica, January 2016, Vol.48(1), pp.34-46
    Description: Over the past three decades, many small‐scale floristic studies of white‐sand forests across the Amazon basin have been published. Nonetheless, a basin‐wide description of both taxonomic and phylogenetic alpha and beta diversity at regional scales has never been achieved. We present a complete floristic analysis of white‐sand forests across the Amazon basin including both taxonomic and phylogenetic diversity. We found strong regional differences in the signal of phylogenetic community structure with both overall and regional Net Relatedness Index and Nearest Taxon Index values found to be significantly positive leading to a pattern of phylogenetic clustering. Additionally, we found high taxonomic dissimilarity but low phylogenetic dissimilarity in pairwise community comparisons. These results suggest that recent diversification has played an important role in the assembly of white‐sand forests causing geographic neo‐endemism patterns at the regional scale. En las últimas tres décadas han sido publicados una serie de estudios florísticos acerca de los bosques Amazónicos sobre arenas blancas que han sido enfocados a escalas espaciales locales. Sin embargo, no ha sido posible obtener una descripción de los patrones de diversidad alfa y beta taxonómica y filogenética a escala de la cuenca Amazónica. Aquí presentamos un análisis florístico completo de los bosques Amazónicos sobre arenas que incluye información sobre diversidad taxonómica y filogenética. Encontramos una fuerte señal en la estructura filogenética de estas comunidades tanto a escala regional como de la cuenca Amazónica en su conjunto, valores significativamente positivos del Índice Neto de Relacionamiento Filogenético (Net Relatedness Index) asi como del Índice del Taxón más Cercano (Nearest Taxon Index) indican que estas comunidades están estructuradas por linajes cercanamente relacionados desde el punto de vista filogenético. Además, encontramos una alta disimilitud taxonómica pero baja disimilitud filogenética cuando comparamos pares de comunidades en relación a la distancia geográfica donde estas se localiza. En conjunto estos resultados sugieren que eventos de diversificación han ocurrido recientemente en la historia geológica de estos bosques y han jugado un papel importante en el ensamblaje de los bosques sobre arenas blancas que a su vez a ha determinado patrones de neo‐endemismo geográfico a escala regional.
    Keywords: Amazon ; Neo‐Endemism ; Phylogenetic Beta Diversity ; Recent Diversification ; White Sands
    ISSN: 0006-3606
    E-ISSN: 1744-7429
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  • 10
    In: European Journal of Neuroscience, January 2007, Vol.25(1), pp.81-86
    Description: Glycogen synthase kinase‐3 (GSK‐3) is a serine/threonine kinase regulating diverse cellular functions including metabolism, transcription and cell survival. Numerous intracellular signalling pathways converge on GSK‐3 and regulate its activity via inhibitory serine‐phosphorylation. Recently, GSK‐3 has been involved in learning and memory and in neurodegeneration. Here, we present evidence that implicates GSK‐3 in synaptic plasticity. We show that phosphorylation at the inhibitory Ser9 site on GSK‐3β is increased upon induction of long‐term potentiation (LTP) in both hippocampal subregions CA1 and the dentate gyrus (DG) . The increase in inhibitory GSK‐3β phosphorylation is robust and persists for at least one hour postinduction. Furthermore, we find that LTP is impaired in transgenic mice conditionally overexpressing GSK‐3β. The LTP deficits can be attenuated/rescued by chronic treatment with lithium, a GSK‐3 inhibitor. These results suggest that the inhibition of GSK‐3 facilitates the induction of LTP and this might explain some of the negative effects of GSK‐3 on learning and memory. It follows that this role of GSK‐3β in LTP might underlie some of the cognitive dysfunction in diseases where GSK‐3 dysfunction has been implicated, including Alzheimer's and other dementias.
    Keywords: Alzheimer'S Disease ; Gsk‐3 ; Mice ; Notch ; Wnt
    ISSN: 0953-816X
    E-ISSN: 1460-9568
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