An Advanced Traffic Engineering Approach Based on the Approximate Invariance of Effective Bandwidths

We present a novel shaping algorithm, called effective bandwidth shaper (EBS), which limits passing data streams' effective bandwidths to a pre-defined upper bound. The shaping algorithm is part of the proposed traffic engineering approach for providing quality of service guarantees to the network users. The traffic engineering approach relies on the property, that effective bandwidths do not change when passing a network node, the so called “invariance property” of effective bandwidths. The algorithm's functionality is verified by application to MPEG video traces. Furthermore, the shaping performance is investigated in different network scenarios with reactive TCP traffic. Our performance studies focus on the dependencies of delays and throughputs upon the number of competing connections, the choice of the space parameter, different TCP protocol variants, and buffer sizes. Moreover we show that the effective bandwidths' invariance when passing a switch, as proven for the case of the many limiting regime (infinitely many sources), holds already for a surprisingly small number of competing flows even in the presence of aggressive TCP traffic.     

Functional Perovskites – From Epitaxial Films to Nanostructured Arrays

Functional perovskite materials gain increasing significance due to their wide spectrum of attractive properties, including ferroelectric, ferromagnetic, conducting and multiferroic properties. Due to the developments of recent years, materials of this type can conveniently be grown, mainly by pulsed laser deposition, in the form of epitaxial films, multilayers, superlattices, and well‐ordered arrays of nanoislands. These structures allow for investigations of preparation–microstructure–property relations. A wide variation of the properties is possible, determined by strain, composition, defect contents, dimensional effects, and crystallographic orientation. An overview of our corresponding work of recent years is given, particularly focusing on epitaxial films, superlattices and nanoisland arrays of (anti)ferroelectric and multiferroic functional perovskites.     

Theoretical and numerical aspects of transmit SENSE

The ideas of parallel imaging techniques, designed to shorten the acquisition time by the simultaneous use of multiple receive coils, can be adapted for parallel transmission of a spatially selective multidimensional RF pulse. In analogy to data acquisition, a multidimensional RF pulse follows a certain trajectory in k-space. Shortening this trajectory shortens the pulse duration. The use of multiple transmit coils, each with its own time-dependent waveform and spatial sensitivity, compensates for the missing parts of k-space. This results in a maintained spatial definition of the pulse profile while its duration is reduced. This paper describes the basic equations of parallel transmission with arbitrarily shaped transmit coils ("Transmit SENSE") focusing on two-dimensional RF pulses. Results of numerical studies are presented demonstrating the theoretical feasibility of the approach.     

Antibacterial Surface Coatings from Zinc Oxide Nanoparticles Embedded in Poly(N‐isopropylacrylamide) Hydrogel Surface Layers

Despite multiple research approaches to prevent bacterial colonization on surfaces, device‐associated infections are currently responsible for about 50% of nosocomial infections in Europe and significantly increase health care costs, which demands development of advanced antibacterial surface coatings. Here, novel antimicrobial composite materials incorporating zinc oxide nanoparticles (ZnO NP) into biocompatible poly(N‐isopropylacrylamide) (PNIPAAm) hydrogel layers are prepared by mixing the PNIPAAm prepolymer with ZnO NP, followed by spin‐coating and photocrosslinking. Scanning electron microscopy (SEM) characterization of the composite film morphology reveals a homogeneous distribution of the ZnO NP throughout the film for every applied NP/polymer ratio. The optical properties of the embedded NP are not affected by the matrix as confirmed by UV‐vis spectroscopy. The nanocomposite films exhibit bactericidal behavior towards Escherichia coli (E. coli) for a ZnO concentration as low as ≈0.74 μg cm^?2 (1.33 mmol cm^?3), which is determined by inductively coupled plasma optical emission spectrometry. In contrast, the coatings are found to be non‐cytotoxic towards a mammalian cell line (NIH/3T3) at bactericidal loadings of ZnO over an extended period of seven days. The differential toxicity of the ZnO/hydrogel nanocomposite thin films between bacterial and cellular species qualifies them as promising candidates for novel biomedical device coatings.     

Plasmonic‐Induced Photon Recycling in Metal Halide Perovskite Solar Cells

Organic–inorganic metal halide perovskite solar cells have emerged in the past few years to promise highly efficient photovoltaic devices at low costs. Here, temperature‐sensitive core–shell Ag@TiO₂ nanoparticles are successfully incorporated into perovskite solar cells through a low‐temperature processing route, boosting the measured device efficiencies up to 16.3%. Experimental evidence is shown and a theoretical model is developed which predicts that the presence of highly polarizable nanoparticles enhances the radiative decay of excitons and increases the reabsorption of emitted radiation, representing a novel photon recycling scheme. The work elucidates the complicated subtle interactions between light and matter in plasmonic photovoltaic composites. Photonic and plasmonic schemes such as this may help to move highly efficient perovskite solar cells closer to the theoretical limiting efficiencies.     

Supramolecular Assembly of Aminoethylene‐Lipopeptide PMO Conjugates into RNA Splice‐Switching Nanomicelles

Phosphorodiamidate morpholino oligomers (PMOs) are oligonucleotide analogs that can be used for therapeutic modulation of pre‐mRNA splicing. Similar to other classes of nucleic acid‐based therapeutics, PMOs require delivery systems for efficient transport to the intracellular target sites. Here, artificial peptides based on the oligo(ethylenamino) acid succinyl‐tetraethylenpentamine (Stp), hydrophobic modifications, and an azide group are presented, which are used for strain‐promoted azide‐alkyne cycloaddition conjugation with splice‐switching PMOs. By systematically varying the lead structure and formulation, it is determined that the type of contained fatty acid and supramolecular assembly have a critical impact on the delivery efficacy. A compound containing linolenic acid with three cis double bonds exhibits the highest splice‐switching activity and significantly increases functional protein expression in pLuc/705 reporter cells in vitro and after local administration in vivo. Structural and mechanistic studies reveal that the lipopeptide PMO conjugates form nanoparticles, which accelerate cellular uptake and that the content of unsaturated fatty acids enhances endosomal escape. In an in vitro Duchenne muscular dystrophy exon skipping model using H2K‐mdx52 dystrophic skeletal myotubes, the highly potent PMO conjugates mediate significant splice‐switching at very low nanomolar concentrations. The presented aminoethylene‐lipopeptides are thus a promising platform for the generation of PMO‐therapeutics with a favorable activity/toxicity profile.     

Polymer Fiber Probes Enable Optical Control of Spinal Cord and Muscle Function In Vivo

Restoration of motor and sensory functions in paralyzed patients requires the development of tools for simultaneous recording and stimulation of neural activity in the spinal cord. In addition to its complex neurophysiology, the spinal cord presents technical challenges stemming from its flexible fibrous structure and repeated elastic deformation during normal motion. To address these engineering constraints, we developed highly flexible fiber probes, consisting entirely of polymers, for combined optical stimulation and recording of neural activity. The fabricated fiber probes exhibit low‐loss light transmission even under repeated extreme bending deformations. Using our fiber probes, we demonstrate simultaneous recording and optogenetic stimulation of neural activity in the spinal cord of transgenic mice expressing the light sensitive protein channelrhodopsin 2 (ChR2). Furthermore, optical stimulation of the spinal cord with the polymer fiber probes induces on‐demand limb movements that correlate with electromyographical (EMG) activity.     

SCR operation mode of diode strings for ESD protection

Diodes and diode strings in 90 nm and beyond technologies are investigated by measurement and device simulation. After a thorough calibration, the device simulator is utilised to achieve a better understanding and an enhanced device performance of diode strings under static and transient ESD conditions. Thereto, parasitic transistors and a so far neglected parasitic thyristor (SCR) in the diode string are regarded, exploited and optimised.     

Geometry-adapted hexahedral meshes improve accuracy of finite-element-method-based EEG source analysis

Mesh generation in finite-element- (FE) method-based electroencephalography (EEG) source analysis generally influences greatly the accuracy of the results. It is thus important to determine a meshing strategy well adopted to achieve both acceptable accuracy for potential distributions and reasonable computation times and memory usage. In this paper, we propose to achieve this goal by smoothing regular hexahedral finite elements at material interfaces using a node-shift approach. We first present the underlying theory for two different techniques for modeling a current dipole in FE volume conductors, a subtraction and a direct potential method. We then evaluate regular and smoothed elements in a four-layer sphere model for both potential approaches and compare their accuracy. We finally compute and visualize potential distributions for a tangentially and a radially oriented source in the somatosensory cortex in regular and geometry-adapted three-compartment hexahedra FE volume conductor models of the human head using both the subtraction and the direct potential method. On the average, node-shifting reduces both topography and magnitude errors by more than a factor of 2 for tangential and 1.5 for radial sources for both potential approaches. Nevertheless, node-shifting has to be carried out with caution for sources located within or close to irregular hexahedra, because especially for the subtraction method extreme deformations might lead to larger overall errors. With regard to realistic volume conductor modeling, node-shifted hexahedra should thus be used for the skin and skull compartments while we would not recommend deforming elements at the grey and white matter surfaces.