Local and global mappings of topology representing networks

As data analysis tasks often have to deal with complex data structures, the nonlinear dimensionality reduction methods play an important role in exploratory data analysis. In the literature a number of nonlinear dimensionality reduction techniques have been proposed (e.g. Sammon mapping, Locally Linear Embedding). These techniques attempt to preserve either the local or the global geometry of the original data, and they perform metric or non-metric dimensionality reduction. Nevertheless, it is difficult to apply most of them to large data sets. There is a need for new algorithms that are able to combine vector quantisation and mapping methods in order to visualise the data structure in a low-dimensional vector space. In this paper we define a new class of algorithms to quantify and disclose the data structure, that are based on the topology representing networks and apply different mapping methods to the low-dimensional visualisation. Not only existing methods are combined for that purpose but also a novel group of mapping methods (Topology Representing Network Map) are introduced as a part of this class. Topology Representing Network Maps utilise the main benefits of the topology representing networks and of the multidimensional scaling methods to disclose the real structure of the data set under study. To determine the main properties of the topology representing network based mapping methods, a detailed analysis of classical benchmark examples (Wine and Optical Recognition of Handwritten Digits data set) is presented.     

Simulation of thermal stress in reinforced concrete at early ages with a simplified model

This paper is primarily concerned with stresses and cracking in reinforced concrete caused by restrained thermal deformations during the hydration process. Simulation of thermal stresses and crack occurrence is carried out with a simplified model. By validation against tests, it is shown that the simple, one-dimensional model gives a reasonable estimate of the thermal stress development. The model is based on a few input parameters like temperature history, stiffness development and tensile strength development. By means of a parametric investigation, the age-dependent stiffness of the concrete and the temperature history are identified as the decisive material characteristics regarding the thermal stress level. It is also found that the reinforcement has no effect prior to cracking but a clear crack redistributing role in the post-cracking state.     

Irrigation, Productivity and Poverty Linkages in Irrigation Systems in Java, Indonesia

This paper analyzes irrigation-poverty linkages, and determines how and to what extent irrigation contributes to poverty alleviation, and whether there are any spatial patterns in poverty in irrigation systems. It also identifies conditions under which irrigation has greater anti-poverty impacts. The analysis is based on primary data collected during the 2000--2001 agricultural year, from four selected irrigation systems and rainfed areas in Java. The results indicate that irrigation has significant poverty reducing impacts. Poverty varies across irrigation systems and across locations within the systems. In general, crop productivity is relatively higher and poverty is lower in middle parts of the systems compared to head and tail parts. Further, locational differences in poverty are more pronounced in larger systems where locational inequities in water distribution and productivity differences are also high. Crop productivity, the size of landholdings and location of households are important determinants of poverty, in addition to demographic factors such as family size. The smaller the systems with well managed infrastructure, relatively equitable water distribution and diversified cropping patterns supported with market infrastructure, the greater the poverty reducing impacts of irrigation. Overall, the study findings suggest that improving the performance of irrigation systems by enhancing land and water productivity, diversifying cropping patterns and improving water distribution across locations would help reduce poverty in presently low productivity-high poverty parts of the systems.     

Evaluation of tRNA intergenic spacer length polymorphism analysis as a molecular method for species identification of streptococcal isolates from bovine mastitis

Sixty-nine bovine mastitis streptococci belonging to the species Str. agalactiae (n = 13), Str. dysgalactiae (n = 16), Str. canis (n = 22), Str. uberis (n = 20) and Str. parauberis (n = 4) and six reference strains of the five streptococcal species were examined for their tRNA gene intergenic length polymorphism (tDNA-ILP) fingerprint pattern. Epidemiologically unrelated isolates from bovine mastitis cases were selected by macrorestriction analysis with pulsed-field gel electrophoresis (PFGE). Their results were compared with those obtained from biochemical and serological studies and with those obtained by PCR-mediated identification amplifying species-specific gene segments of the five streptococcal species. According to the present results tDNA-ILP allowed a correct identification of all Str. agalactiae, Str. uberis and Str. parauberis strains investigated also including the reference strains of each species showing species-specific banding pattern. However, all Str. dysgalactiae ssp. dysgalactiae and all Str. canis strains appeared with an undistinguishable pattern which did not allow an identification of the species.     

Laser structuring for back junction silicon solar cells

We demonstrate mask‐free fabrication of a 22·0%‐efficient crystalline Si solar cell by applying laser ablation of Si and by laser ablation of protective coatings. The bulk absorber material is a p ‐type float zone silicon wafer and the designated cell area is 4 cm². While the processing time of our laboratory‐type of laser system is far too slow for industrial processing, we estimate on the basis of our experiments that laser processing of 12·5 × 12·5 cm²‐sized solar cells in just a few seconds is feasible with commercially available equipment. Copyright © 2006 John Wiley & Sons, Ltd.     

Hydrothermal treatments of two cowpea (Vigna unguiculata L. Walp) varieties: effect of micronisation on physicochemical and structural characteristics

The effects of a hydrothermal treatment consisting of tempering (to 41% moisture) and heating to 153 °C (micronisation) on the structural and physicochemical characteristics of two cowpea varieties were studied. The untreated varieties had similar cooking times, although cooked Bechuana white cowpeas were significantly (P ≤ 0.05) softer and had a higher incidence of splitting than Var. 462 cowpeas. This may be due in part to differences in cotyledon structure affecting water uptake during cooking. The hydrothermal treatment changed the physical structure and chemical properties of the cowpea seeds. This led to significant (P ≤ 0.05) reductions in the cooking time of micronised Bechuana white and Var. 462 cowpeas, by 47 and 36% respectively, as compared with control samples. Micronisation caused physical fissuring of the seed coat and cotyledon and significantly (P ≤ 0.05) reduced the bulk density of treated seeds. These changes in the physical structure significantly (P ≤ 0.05) improved the initial water uptake during soaking and cooking, increased the enzyme‐susceptible starch and reduced the protein solubility and hydration capacity of the cowpea seeds. Cooked (60 min) micronised cowpeas also had significantly (P ≤ 0.05) more splits and a significantly (P ≤ 0.05) softer texture than control samples. Copyright © 2005 Society of Chemical Industry     

Fungi associated with Indonesian dried fish

The mycoflora of dried salted fish from Indonesia was studied, with emphasis on visibly spoiled fish and spoilage fungi. A total of 364 isolates from 74 fish were cultured and identified. The most prevalent fungus was a previously undescribed species, now named Polypaecilum pisce, which was isolated from 42% of the fish examined, in extreme cases appearing as conspicuous white growth over large areas of the fish surface. Other frequently isolated species were Eurotium rubrum (35%), E. repens (26%), E. amstelodami (22%), E. chevalieri (18%), Aspergillus niger (37%), A. flavus (27%), A. sydowii (23%), A. penicilloides (16%) and A. wentii (15%). A variety of Penicillium species and species from 17 other genera were isolated less frequently.     

Quality Improvement of Fresh-Cut Endive (<Emphasis Type="Italic">Cichorium endivia</Emphasis> L.) and Recycling of Washing Water by Low-Dose UV-C Irradiation

Superficial short-wavelength ultraviolet (UV-C) treatment (1.2 kJ/m²) of fresh-cut endive was combined with conventional cold (4 °C, 120 s) and innovative warm (45 °C, 120 s) water washing prior to and after irradiation in order to improve its microbial and sensory quality including physiological properties. UV-C doses applied exerted only minor physiological stress on the plant tissue, irrespective of the washing procedure as indicated by largely unaltered headspace gas compositions, chlorophyll fluorescence maximum quantum yields (F _v/F _m), and retention of chlorophylls and β-carotene. Independent of the washing procedure applied, phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD) activities were slightly inhibited by UV-C irradiation. As a result of UV-C irradiation, significantly improved microbiological and sensory quality was retained during the entire storage period, particularly, when applied after washing. Being applicable in organic fresh-cut production, UV-C represents a valuable alternative to chlorine application to washing water. The most efficient decontamination (2.1 log₁₀ units) of fresh-cut endive was achieved by combining warm water washing with subsequent UV-C irradiation. Furthermore, when UV-C lamps were integrated into the water tank of a continuous industrial washing machine, the microbial loads of the process water were also significantly lowered. Accordingly, in-line UV-C decontamination of process water may be instrumental in minimizing both fresh water consumption and the risk of cross-contamination.