Simple-cell-like receptive fields maximize temporal coherence in natural video

Recently, statistical models of natural images have shown the emergence of several properties of the visual cortex. Most models have considered the nongaussian properties of static image patches, leading to sparse coding or independent component analysis. Here we consider the basic time dependencies of image sequences instead of their nongaussianity. We show that simple-cell-type receptive fields emerge when temporal response strength correlation is maximized for natural image sequences. Thus, temporal response strength correlation, which is a nonlinear measure of temporal coherence, provides an alternative to sparseness in modeling simple-cell receptive field properties. Our results also suggest an interpretation of simple cells in terms of invariant coding principles, which have previously been used to explain complex-cell receptive fields.     

The effect of inspection and repair on the size distributions of the weld imperfections in nuclear power plant pipes

The weld defects appearing in the pipes of the main steam system in a BWR power plant were studied. The effect of inspection rejection and repair on the imperfection size distribution was analysed. The size distributions before and after the inspection rejection as well as after the repair procedure were of the form a + b/x², where x is the imperfection size and a and b are coefficients. The portion of the rejected defects had the size dependence near to the form of the cumulative Gaussian function. The effect of repair on the initial size distribution had the form of the cumulative Poisson distribution.     

Reliability of 80 μm pitch flip chip attachment on flex

The interest toward flip chip technology has increased rapidly during last decade. Compared to the traditional packages and assembly technologies flip chip has several benefits, like less parasitics, the small package size and the weight. These properties emphasize especially when flip chip component is mounted direct to the flexible printed board. In this paper flip chip components with Kelvin four point probe and daisy chain test structure were bonded to the polyimide flex with two different types of anisotropically conductive adhesive films and one anisotropically conductive adhesive paste. The reliability of small pitch flip chip on flex interconnections (pitch 80 μm) was tested in 85°C/85% RH environmental test and −40↔+125°C thermal shock test. According to the results it is possible to achieve reliable and stable ohmic contact, even in small pitch flip chip on flex applications.     

IEEE 802.11ac MIMO Transceiver Baseband Processing on a VLIW Processor

Wireless standards are evolving rapidly due to the exponential growth in the number of portable devices along with the applications with high data rate requirements. Adaptable software based signal processing implementations for these devices can make the deployment of the constantly evolving standards faster and less expensive. The flagship technology from the IEEE WLAN family, the IEEE 802.11ac, aims at achieving very high throughputs in local area connectivity scenarios. This article presents a software based implementation for the Multiple Input and Multiple Output (MIMO) transmitter and receiver baseband processing conforming to the IEEE 802.11ac standard which can achieve transmission bit rates beyond 1Gbps. This work focuses on the Physical layer frequency domain processing. Various configurations, including 2×2 and 4×4 MIMO are considered for the implementation. To utilize the available data and instruction level parallelism, a DSP core with vector extensions is selected as the implementation platform. Then, the feasibility of the presented software-based solution is assessed by studying the number of clock cycles and power consumption of the different scenarios implemented on this core. Such Software Defined Radio based approaches can potentially offer more flexibility, high energy efficiency, reduced design efforts and thus shorter time-to-market cycles in comparison with the conventional fixed-function hardware methods.     

In vitro blood and fibroblast responses to BisGMA–TEGDMA/bioactive glass composite implants

This in vitro study was designed to evaluate both blood and human gingival fibroblast responses to bisphenol A–glycidyl methacrylate–triethyleneglycol dimethacrylate (BisGMA–TEGDMA)/bioactive glass (BAG) composite, aimed to be used as composite implant abutment surface modifier. Three different types of substrates were investigated: (a) plain polymer (BisGMA 50 wt%–TEGDMA 50 wt%), (b) BAG–composite (50 wt% polymer + 50 wt% fraction of BAG–particles, <50 μm), and (c) plain BAG plates (100 wt% BAG). The blood response, including the blood–clotting ability and platelet adhesion morphology were evaluated. Human gingival fibroblasts were plated and cultured on the experimental substrates for up to 10 days, then the cell proliferation rate was assessed using AlamarBlue assay?. The BAG–composite and plain BAG substrates had a shorter clotting time than plain polymer substrates. Platelet activation and aggregation were most extensive, qualitatively, on BAG–composite. Analysis of the normalized cell proliferation rate on the different surfaces showed some variations throughout the experiment, however, by day 10 the BAG–composite substrate showed the highest (P < 0.001) cell proliferation rate. In conclusion, the presence of exposed BAG–particles enhances fibroblast and blood responses on composite surfaces in vitro.     

Elevated Ozone Modulates Herbivore-Induced Volatile Emissions of <Emphasis Type="Italic">Brassica nigra</Emphasis> and Alters a Tritrophic Interaction

Plants damaged by herbivores emit volatile organic compounds (VOCs) that are used by parasitoids for host location. In nature, however, plants are exposed to multiple abiotic and biotic stresses of varying intensities, which may affect tritrophic interactions. Here, we studied the effects of ozone exposure and feeding by Pieris brassicae larvae on the VOCs emitted by Brassica nigra and the effects on oriented flight of the parasitoid Cotesia glomerata. We also investigated the oriented flight of C. glomerata in a wind-tunnel with elevated ozone levels. Herbivore-feeding induced the emission of several VOCs, while ozone alone had no significant effect. However, exposure to 120 ppb ozone, followed by 24 hr of herbivore-feeding, induced higher emissions of all VOCs as compared to herbivore-feeding alone. In accordance, herbivore-damaged plants elicited more oriented flights than undamaged plants, whereas plants exposed to 120 ppb ozone and 24 hr of herbivore-feeding elicited more oriented flights than plants subjected to herbivore-feeding alone. Ozone enrichment of the wind-tunnel air appeared to negatively affect orientation of parasitoids at 70 ppb, but not at 120 ppb. These results suggest that the combination of ozone and P. brassicae-feeding modulates VOC emissions, which significantly influence foraging efficiency of C. glomerata.     

Impact of 3G and beyond technology development and pricing on mobile data service provisioning,usage and diffusion

This study investigates the third generation mobile telecommunication systems (3G) diffusion challenges in the situation where large-scale mobile data service usage has not yet broken through. The paper first analyzes incumbent mobile operator business prospects in a large Western-European country. The results suggest that rollout of the most advanced available 3G technologies pay back through increased data service usage and revenues in the situation of declining voice revenues. In the main body of the study we discuss different pricing models and demonstrate that the flat rate pricing of data services, supplemented with certain conditions, supports the large-scale take-up of mobile data services. It boosts the usage of mobile data services and provides a competitive and sustainable business model for the operators and other market actors at the same time. Our modeling indicates furthermore, that flat rate model, combined with open access, gives better incentives to rollout high-speed mobile technologies to the rural areas, than the traffic-based charging.