Illuminating the BOLD signal: combined fMRI-fNIRS studies

Functional magnetic resonance imaging (fMRI) is currently combined with electrophysiological methods to identify the relationship between neuronal activity and the blood oxygenation level-dependent (BOLD) signal. Several processes like neuronal activity, synaptic activity, vascular dilation, blood volume and oxygenation changes underlie both response modalities, that is, the electrophysiological signal and the vascular response. However, accessing single process relationships is absolutely mandatory when aiming at a deeper understanding of neurovascular coupling and necessitates studies on the individual building blocks of the vascular response. Combined fMRI and functional near-infrared spectroscopy studies have been performed to validate the correlation of the BOLD signal to the hemodynamic changes in the brain. Here we review the current status of the integration of both technologies and judge these studies in the light of recent findings on neurovascular coupling.     

Effect of the primary particle morphology on the micromechanical properties of nanostructured alumina agglomerates

Depending on the application of nanoparticles, certain characteristics of the product quality such as size, morphology, abrasion resistance, specific surface, dispersibility and tendency to agglomeration are important. These characteristics are a function of the physicochemical properties, i.e. the micromechanical properties of the nanostructured material. The micromechanical properties of these nanostructured agglomerates such as the maximum indentation force, the plastic and elastic deformation energy and the strength give information on the product properties, e.g. the efficiency of a dispersion process of the agglomerates, and can be measured by nanoindentation. In this study a Berkovich indenter tip was used for the characterisation of model aggregates out of sol–gel produced silica and precipitated alumina agglomerates with different primary particle morphologies (dimension of 15–40 nm). In general, the effect of the primary particle morphology and the presence or absence of solid bonds can be characterised by the measurement of the micromechanical properties via nanoindentation. The micromechanical behaviour of aggregates containing solid bonds is strongly affected by the elastic–plastic deformation behaviour of the solid bonds and the breakage of solid bonds. Moreover, varying the primary particle morphology for similar particle material and approximately isotropic agglomerate behaviour the particle–particle interactions within the agglomerates can be described by the elementar breaking stress according to the formula of Rumpf.     

Nanofiber-based double-helix dipole trap for cold neutral atoms

A double-helix optical trapping potential for cold atoms can be straightforwardly created inside the evanescent field of an optical nanofiber. It suffices to send three circularly polarized light fields through the nanofiber; two counterpropagating and far red-detuned with respect to the atomic transition and the third far blue-detuned. Assuming realistic experimental parameters, the transverse confinement of the resulting potential allows one to reach the one-dimensional regime with cesium atoms for temperatures of several μK. Moreover, by locally varying the nanofiber diameter, the radius and pitch of the double-helix can be modulated, thereby opening a realm of applications in cold-atom physics.     

Derivations having divergence zero onR[X,Y]

In this paper it is proved that for any ℚ-algebraR any locally nilpotentR-derivationD onR[X,Y] having divergence zero and 1 ∈ (D(X),D(Y)) (i) has a slice, and (ii)A ^D =R[P] for someP. Furthermore, it is shown that any surjectiveR-derivation onR[X,Y] having divergence zero is locally nilpotent. Connections with the Jacobian Conjecture are made.     

Das Vorkommen von Aconits?ure im Zuckerrohrsaft und Colonialzucker

Ohne Zusammenfassung     

Ueber die Darstellung von Traubenzucker

Ohne Zusammenfassung