Tissue-level segmentation and tracking of cells in growing plant roots

With the spread of systems approaches to biological research, there is increasing demand for methods and tools capable of extracting quantitative measurements of biological samples from individual and time-based sequences of microscope images. To this end, we have developed a software tool for tissue level segmentation and automatic tracking of a network of cells in confocal images of the roots of the model plant Arabidopsis thaliana. The tool implements a novel hybrid technique, which is a combination of the recently developed Network Snakes technique and MCMC-based particle filters and incorporates automatic initialisation of the network snakes. A novel method of evaluation of network-structured multi-target tracking is also presented, and is used to evaluate the developed tracking framework for accuracy and robustness against several timelapse sequences of Arabidopsis roots. Evaluation results are presented, along with a comparison between the results of the component techniques and the hybrid approach. The results show that the hybrid approach performed consistently well at all levels of complexity and better than the component methods alone.     

The unintended consequences of government policies and programmes for public open spaces in inner-urban Sydney

Sport is important internationally; but in Australia, it is part of the national identity. The enjoyment of public open space for sport is, therefore, an assumed community right. We interviewed key staff from inner Sydney councils about management issues associated with public open space. The greatest concern was sporting fields – formal and informal – which were considered to have exceeded carrying capacity mainly because of the unintended outcomes of government programmes/policies spanning; (1) ‘healthy lifestyles’ which increased public open space use; (2) ‘urban consolidation’ increased inner-city population density with associated increased usage and loss of open space; (3) ‘temporal water restriction’ during drought (not ‘water budgets’) which intensify management issues; and (4) ‘building the education revolution’, meaning that public open space lost from schools results in increased pressure on public open space. Consequences have increased human pressure on public open space without commensurate consideration for the management and/or expansion of these areas.     

Thermosetting polyurethane multiwalled carbon nanotube composites

Thermosetting polyurethane (PU) multi‐walled carbon nanotube (MWCNT) nanocomposites at loadings up to 1 wt % were prepared via an addition polymerization reaction. The morphology of the nanocomposites and degree of dispersion of the MWCNTs was studied using a combination of scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and wide angle X‐ray diffraction (WAXD), and revealed the nanotubes to be highly dispersed in the PU matrix. Addition of just 0.1 wt % MWCNTs resulted in significant enhancements in stiffness, strength and toughness. Increases in Young's modulus, % elongation at break and ultimate tensile strength of 561, 302 and 397% were measured for the nanocomposites compared to the unfilled PU. The effect of the MWCNTs on the modulus of the PU was evaluated using the Rule of Mixtures, Krenchel and Halpin‐Tsai models. Only the Halpin‐Tsai model applied to high aspect ratio nanotubes was in good agreement with the modulus values determined experimentally. Strong interfacial shear stress was found between PU chains and nanotubes, up to 439 MPa, calculated using a modified Kelly‐Tyson model. Evidence for strong interfacial interactions was obtained from the Raman spectra of both the precursor materials and nanocomposites. When the MWCNTs were added to the isophorone diisocyanate an up‐shift of 14 cm^?1 and on average 40 cm^?1 was obtained for the position of the carbon‐hydrogen (C? H) out‐of plane bending (766 cm^?1) and isocyanate symmetric stretch (1420 cm^?1) modes respectively. Moreover, an up‐shift of 24 cm^?1 was recorded for the nanotube tangential mode (G‐band) for the 1.0 wt % nanocomposite because of the compressive forces of the PU matrix acting on the MWCNTs. The dynamic mechanical (DMA) properties of the PU thermoset and the nanocomposites were measured as a function of temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Multi-walled carbon nanotube modified carbon paste electrode as an electrochemical sensor for the determination of epinephrine in the presence of ascorbic acid and uric acid

A biocompatible electrochemical sensor for selective detection of epinephrine (EP) in the presence of 1000-fold excess of ascorbic acid (AA) and uric acid (UA) was fabricated by modifying the carbon paste electrode (CPE) with multi-walled carbon nanotubes (MWCNTs) using a casting method. The electro-catalytic activity of the modified electrode for the oxidation of EP was investigated. The current sensitivity of EP was enhanced to about five times upon modification. A very minimum amount of modifier was used for modification. The voltammetric response of EP was well resolved from the responses of AA and UA. The electrochemical impedance spectroscopic (EIS) studies reveal the least charge transfer resistance for the modified electrode. The AA peak that is completely resolved from that of EP at higher concentrations of AA and the inability of the sensor to give an electrochemical response for AA below a concentration of 3.0 × 10^? 4 M makes it a unique electrochemical sensor for the detection of EP which is 100% free from the interference of AA. Two linear dynamic ranges of 1.0 × 10^? 4–1.0 × 10^? 5 and 1.0 × 10^? 5–5.0 × 10^? 7 M with a detection limit of 2.9 × 10^? 8 M were observed for EP at modified electrode. The practical utility of this modified electrode was demonstrated by detecting EP in spiked human blood serum and EP injection. The modified electrode is highly reproducible and stable with anti fouling effects.     

Sequestration of zinc from zinc oxide nanoparticles and life cycle effects in the sediment dweller amphipod Corophium volutator

We studied the effects of ZnO nanoparticles [ZnO NPs, primary particle size 35 ± 10 nm (circular diameter, TEM)], bulk [160 ± 81 nm (circular diameter, TEM)], and Zn ions (from ZnCl(2)) on mortality, growth, and reproductive endpoints in the sediment dwelling marine amphipod Corophium volutator over a complete lifecycle (100 days). ZnO NPs were characterized by size, aggregation, morphology, dissolution, and surface properties. ZnO NPs underwent aggregation and partial dissolution in the seawater exposure medium, resulting in a size distribution that ranged in size from discrete nanoparticles to the largest aggregate of several micrometers. Exposure via water to all forms of zinc in the range of 0.2-1.0 mg L(-1) delayed growth and affected the reproductive outcome of the exposed populations. STEM-EDX analysis was used to characterize insoluble zinc precipitates (sphaerites) of high sulfur content, which accumulated in the hepatopancreas following exposures. The elemental composition of the sphaerites did not differ for ZnO NP, Zn(2+), and bulk ZnO exposed organisms. These results provide an illustration of the comparable toxicity of Zn in bulk, soluble, and nanoscale forms on critical lifecycle parameters in a sediment dwelling organism.     

Factor structure of the Child Behavior Checklist/6-18 in a sample of girls adopted from China.

Confirmatory factor analysis with robust weighted least squares estimation of the 103 dichotomously scored items of the Child Behavior Checklist/6-18 (T. M. Achenbach & L. A. Rescorla, 2001) in a sample of 516 girls adopted from China (ages 6.0-15.7 years; M = 8.2, SD = 1.9) indicated that the fit of the 8-factor model was good (root-mean-square error of approximation = .047) and was slightly better than what T. M. Achenbach and L. A. Rescorla (2001) reported for the same model (.06). Support for the 2nd-order factor structure of Internalizing and Externalizing Problems also was provided. Comparisons of the mean scores for the syndromes and Internalizing, Externalizing, and Total Problems revealed mostly small differences between the sample of adopted Chinese girls and T. M. Achenbach and L. A. Rescorla's normative samples. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Building-integrated PV installations in the Netherlands: Examples and operational experiences

Building-integrated PV started receiving attention in the Netherlands around 1990. Attention has ever since been focusing on the integration of PV into new dwellings. Efforts have resulted in cost reductions, performance improvements, the development of new integration products and the creation of a network with utilities, property developers, architects, building companies and local authorities. PV system costs have been reduced by one third, to 5 Euro in 2000. System performance has gone up slightly during the reporting period, further reducing the costs per unit energy produced. Inverter costs have gone down from 1.5 Euro/Wp in 1991 to 0.5 Euro/Wp in 2000. Concerning integration into buildings and the building process, the Netherlands PV programme has been concentrating on developing products for low-cost integration into sloped roofs of new buildings. Watertight profile systems have been developed, tested, and applied in projects on a growing scale. The costs for building integration have come down due to improvements in integration systems, the electric system and in installation procedures. Projects have also been carried out on an increasing scale to learn about the integration of PV into the building process. In total, a capacity of more than 8 MW was installed by the end of the year 1999, with projects ranging from individual dwellings and offices to solar cities such as the Nieuw Sloten project in Amsterdam (250 kWp) and Nieuwland in Amersfoort (1 MW). Now, at the turn of the century, plans are being derived to give PV the ‘boost’ to become commercially viable within the next 7 to 10 years. For this, an ambitious goal is being formulated by government together with the PV industry, utilities, the building sector and others involved in PV in the Netherlands. Already in the mid-1990s, the long-term energy programme of the ministry of Economic Affairs set the target at an installed PV capacity of 250 MWp by the year 2010. In order to achieve a commercially viable market within the next 7 to 10 years, however, a goal of 500 MWp installed PV capacity would be required. Recent research shows that such a target is ambitious, but achievable if supported by dedicated government programmes, investments by industry and contributions of the building and utility sector.