Use of near-infrared radiation for oxygenic photosynthesis via photon up-conversion

Radiation between 400 and 700 nm, used for oxygenic photosynthesis by cyanobacteria, algae and plants, represents only 44% of total solar energy while the range above 700 nm comprises 52%. An ability to use near infrared (NIR, 700–1200 nm) radiation would greatly improve the efficiency of photosynthesis, but NIR photons have too low energy to excite the photosystems of oxygenic photosynthesis. Here we show that a mechanism called photon up-conversion can turn NIR radiation into an energy source for photosynthesis. In the future, it may be possible to up-convert the NIR part of the solar energy flux to visible light for use in photo-induced biohydrogen production by oxygenic photosynthesis.     

Flow-optimized random access for wireless multihop networks

We study elastic traffic performance in time-slotted wireless random access networks, where the link access probabilities are adjusted at flow level each time a new flow (file transfer) arrives or a flow in progress terminates. By defining the capacity sets of such networks we carry out performance analysis in a dynamic setting, where the flows come and go and share the resources according to the balanced fairness principle. We derive flow throughput analytically for three special scenarios and devise an algorithm for general networks. At low loads, flow-optimized random access yields almost the same performance as optimal/deterministic scheduling.     

PicSOM – content-based image retrieval with self-organizing maps

We have developed a novel system for content-based image retrieval in large, unannotated databases. The system is called PicSOM, and it is based on tree structured self-organizing maps (TS-SOMs). Given a set of reference images, PicSOM is able to retrieve another set of images which are similar to the given ones. Each TS-SOM is formed with a different image feature representation like color, texture, or shape. A new technique introduced in PicSOM facilitates automatic combination of responses from multiple TS-SOMs and their hierarchical levels. This mechanism adapts to the user's preferences in selecting which images resemble each other. Thus, the mechanism implements a relevance feedback technique on content-based image retrieval. The image queries are performed through the World Wide Web and the queries are iteratively refined as the system exposes more images to the user.     

Self-Organising Maps as a Relevance Feedback Technique in Content-Based Image Retrieval

Self-Organising Maps (SOMs) can be used in implementing a powerful relevance feedback mechanism for Content-Based Image Retrieval (CBIR). This paper introduces the PicSOM CBIR system, and describes the use of SOMs as a relevance feedback technique in it. The technique is based on the SOM’s inherent property of topology-preserving mapping from a high-dimensional feature space to a two-dimensional grid of artificial neurons. On this grid similar images are mapped in nearby locations. As image similarity must, in unannotated databases, be based on low-level visual features, the similarity of images is dependent on the feature extraction scheme used. Therefore, in PicSOM there exists a separate tree-structured SOM for each different feature type. The incorporation of the relevance feedback and the combination of the outputs from the SOMs are performed as two successive processing steps. The proposed relevance feedback technique is described, analysed qualitatively, and visualised in the paper. Also, its performance is compared with a reference method.     

Downstream Hydrological Impacts of Hydropower Development in the Upper Mekong Basin

The Mekong River Basin in Southeast Asia is experiencing extensive hydropower development. Concerns have been raised about the consequences of the development for the ecosystems, livelihoods and food security in the region. The largest planned hydropower dam cascade in the basin, the Lancang-Jiang cascade, is currently under construction and already partly built into the Upper Mekong Basin, China. In this paper we assess the impact of the Lancang-Jiang cascade on downstream hydrology by using a combination of a hydrological model and a reservoir cascade optimization model. The hydrological changes were quantified in detail at the Chiang Saen gauging station in Thailand, the first gauge station downstream from the cascade, and in lesser detail at four other downstream locations in the Mekong mainstream. We found that on average the Lancang-Jiang cascade increased the December?CMay discharge by 34?C155?% and decreased the July?CSeptember discharge by 29?C36?% at Chiang Saen. Furthermore, the Lancang-Jiang cascade reduced (increased) the range of hydrological variability during the wet season (dry season) months. The dry season hydrological changes were significant also in all downstream gauging stations, even as far as Kratie in Cambodia. Thus the Mekong??s hydrological regime has been significantly altered by the Lancang-Jiang cascade, but what the consequences are for ecosystems and livelihoods, needs further study.     

On the implicit integration of rate‐dependent inelastic constitutive models

Although there are many different algorithms for the integration of inelastic constitutive models, the fully implicit backward Euler method has become the most popular one. In this study further investigations on the accuracy of the backward Euler method have been carried out. Also the performance of the discontinuous Galerkin family and some implicit Runge–Kutta time integrators is evaluated. By using a simple scalar model problem accuracy of some integrators is studied when a single finite time step is applied. Conclusions drawn from this scalar model problem has been verified to apply also to a full six‐dimensional strain space formulation by numerical means. Special emphasis is placed on rate‐dependent inelastic creep models. Copyright © 2005 John Wiley & Sons, Ltd.     

Dual Antenna Receivers for High Data Rate Terminals

In this paper, dual antenna receiver architectures are studied including RAKE, chip-level linear equalizer, and their combination. The arithmetic complexity of single and dual antenna receiver methods is analyzed. Cost of such receivers when implemented with customized hardware or software on application-specific instruction set processors (ASIP) is estimated. The study shows that feasible dual antenna detection can be obtained with less than 70% additional costs. More flexible implementation supporting several standards can be obtained with software but it requires higher power consumption due to additional memory.     

Variation in Birch (<Emphasis Type="Italic">Betula pendula</Emphasis>) Shoot Secondary Chemistry due to Genotype,Environment, and Ontogeny

Plant secondary chemistry is determined by both genetic and environmental factors, and large intraspecific variation in secondary chemistry has frequently been reported. The heritability of specific tree secondary metabolites is, however, mostly unknown. We tested the effect of plant genotype, environment, and ontogeny on the variation in shoot secondary chemistry of juvenile and mature European white birches (Betula pendula). Phenolic compounds and triterpenoids were analyzed in 30 naturally regenerated 20-year-old parental trees and micropropagated plantlets that originated from 14 of those same parental trees, planted at four growing sites. Most of the variation for phenolic compounds was explained by differences between parental trees, whereas triterpenoids had a high variation both between parental trees and within the canopy of individual tree. The effect of ontogeny was strong for some individual compounds. In mature trees, the amount of triterpenoids was less than 1 mg/g (DW), whereas the concentration in juvenile plantlets was up to 64 mg/g (DW). Clonal plantlets and parental trees were generally quite similar in their phenolic contents, but there were significant differences for all analyzed compounds among clones. Environment had no significant effect on the accumulation of some compounds, whereas for others, a significant environmental effect and/or significant genotype by environment interaction was found. These results suggest that birch shoot secondary chemistry is under strong genetic control and that the environmental effects depend on the studied chemical trait.     

Tryptose-sulfite-cycloserine-egg yolk agar membrane filter method for the detection of Clostridium perfringens in water

A report on the use of the tryptose-sulfite-cycloserine-egg yolk agar membrane filter method for the detection of Clostridium perfringens in natural and artificial water samples is given. The method, which was compared with a tube colony count method, proved to be reliable and simple for practical use.     

BelBaieV夹网成形器

BelBaieV继承了Beloit BelBaiell和BelBaieⅢ型夹网成形器成纸匀度良好的特征,可提高脱水能力,减少两面差,并提高纸机潜在的工作车速,从而提高纸机的生产能力.本文介绍了BelBaieV成形器的结构特征、优点、使用效果等.