Tapered hygo-thermally curvature-stable laminates with non-standard ply orientations

Stacking sequence configurations for hygro-thermally curvature-stable (HTCS) laminates have recently been identified in nine unique classes of coupled laminate with standard ply angle orientations +45, −45, 0 and 90°. All arise from the judicious re-alignment of the principal material axis of laminate classes with Bending-Twisting and/or Bending-Extension and Twisting-Shearing coupling; where off-axis material alignment of these parent classes gives rise to distinctly different mechanical coupling behaviour. However, for standard ply angle orientations, HTCS solutions were found in only 8-, 12-, 16- and 20-ply laminates. This article considers non-standard ply angle orientations +60, −60, 0 and 90°, which lead to solutions in all ply number groupings for 10 plies and above, thus offering a possibility for ply terminations and hence tapered HTCS laminate designs

Hydroxyurea-induced synchronisation of bloodstream stage Trypanosoma brucei

Synchronisation of the <i>Trypanosoma brucei</i> cell cycle proved elusive for many years. A recent report demonstrated that synchronisation of procyclic form cells was possible following treatment with hydroxyurea. Here, that work is extended to the disease-relevant, mammalian-infective bloodstream stage trypanosome. Treatment of bloodstream stage Lister 427 <i>T. Brucei</i> cells growing <i>in vitro</i> with 10 μg ml<sup>−1</sup> hydroxyurea for 6 h led to an enrichment of cells in S phase. Following removal of the drug, cells proceeded uniformly through one round of the cell cycle, providing a much needed tool to enrich for specific cell cycle stages, in a manner similar to hydroxyurea treatment of procyclic form <i>T. brucei.</i&gt

On diffraction within a dielectric medium as an example of the Minkowski formulation of optical momentum

The Abraham-Minkowski dilemma relates to the disputed value of the optical momentum within a dielectric medium and whether the free-space value should be divided (Abraham) or multiplied (Minkowski) by the refractive index. Although undoubtedly simplistic, these two approaches provide intuitive insight to many subtle problems in optical physics. This paper reviews a modified version of the Einstein box argument that supports an Abraham formulation, then considers diffraction within a dielectric medium and shows it supports a simple Minkowski formulation, i.e. that the optical momentum should be multiplied by the refractive index

Alignment verification for electron beam lithography

Alignment between lithography layers is essential for device fabrication. A minor defect in a single marker can lead to incorrect alignment and this can be the source of wafer reworks. In this paper we show that this can be prevented by using extra alignment markers to check the alignment during patterning, rather than inspecting vernier patterns after the exposure is completed. Accurate vernier patterns can often only be read after pattern transfer has been carried out. We also show that by using a Penrose tile as a marker it is possible to locate the marker to about 1 nm without fully exposing the resist. This means that the marker can be reused with full accuracy, thus improving the layer to layer alignment accuracy. Lithography tool noise limits the process

SamACO: variable sampling ant colony optimization algorithm for continuous optimization

An ant colony optimization (ACO) algorithm offers algorithmic techniques for optimization by simulating the foraging behavior of a group of ants to perform incremental solution constructions and to realize a pheromone laying-and-following mechanism. Although ACO is first designed for solving discrete (combinatorial) optimization problems, the ACO procedure is also applicable to continuous optimization. This paper presents a new way of extending ACO to solving continuous optimization problems by focusing on continuous variable sampling as a key to transforming ACO from discrete optimization to continuous optimization. The proposed SamACO algorithm consists of three major steps, i.e., the generation of candidate variable values for selection, the ants’ solution construction, and the pheromone update process. The distinct characteristics of SamACO are the cooperation of a novel sampling method for discretizing the continuous search space and an efficient incremental solution construction method based on the sampled values. The performance of SamACO is tested using continuous numerical functions with unimodal and multimodal features. Compared with some state-of-the-art algorithms, including traditional ant-based algorithms and representative computational intelligence algorithms for continuous optimization, the performance of SamACO is seen competitive and promising

"Getting sicker quicker": does living in a more deprived neighbourhood mean your health deteriorates faster?

Data from the longitudinal West of Scotland Twenty-07 Study: Health in the Community was used to examine whether, over a 20 year period, the self-reported health of people living in deprived areas became poorer faster compared to those living in more affluent areas. Three cohorts (born in the early 1930s, 1950s and 1970s) are included, covering 60 years of the life span. Using multilevel growth curve models, a 40% probability of reporting poor health was predicted among residents of more deprived areas at an earlier age (66) compared to those living in more affluent areas (83). Wider area differences were seen for men than for women. Our findings indicate that attempts to reduce area differences in health should start young but also continue throughout the lifespan

The malaria parasite cyclic GMP-dependent protein kinase plays a central role in blood-stage schizogony

A role for the Plasmodium falciparum cyclic GMP (cGMP)-dependent protein kinase (PfPKG) in gametogenesis in the malaria parasite was elucidated previously. In the present study we examined the role of PfPKG in the asexual blood-stage of the parasite life cycle, the stage that causes malaria pathology. A specific PKG inhibitor (compound 1, a trisubstituted pyrrole) prevented the progression of P. falciparum schizonts through to ring stages in erythrocyte invasion assays. Addition of compound 1 to ring-stage parasites allowed normal development up to 30 h postinvasion, and segmented schizonts were able to form. However, synchronized schizonts treated with compound 1 for ≥6 h became large and dysmorphic and were unable to rupture or liberate merozoites. To conclusively demonstrate that the effect of compound 1 on schizogony was due to its selective action on PfPKG, we utilized genetically manipulated P. falciparum parasites expressing a compound 1-insensitive PfPKG. The mutant parasites were able to complete schizogony in the presence of compound 1 but not in the presence of the broad-spectrum protein kinase inhibitor staurosporine. This shows that PfPKG is the primary target of compound 1 during schizogony and provides direct evidence of a role for PfPKG in this process. Discovery of essential roles for the P. falciparum PKG in both asexual and sexual development demonstrates that cGMP signaling is a key regulator of both of these crucial life cycle phases and defines this molecule as an exciting potential drug target for both therapeutic and transmission blocking action against malaria

Investigation into background levels of small organic samples at the NERC Radiocarbon Laboratory

Recent progress in preparation/combustion of submilligram organic samples at our laboratories is presented. Routine methods had to be modified/refined to achieve acceptable and consistent procedural blanks for organic samples smaller than 1000 g C. A description of the process leading to a modified combustion method for smaller organic samples is given in detail. In addition to analyzing different background materials, the influence of different chemical reagents on the overall radiocarbon background level was investigated, such as carbon contamination arising from copper oxide of different purities and from different suppliers. Using the modified combustion method, small amounts of background materials and known-age standard IAEA-C5 were individually combusted to CO2. Below 1000 g C, organic background levels follow an inverse mass dependency when combusted with the modified method, increasing from 0.13 0.05 pMC up to 1.20 0.04 pMC for 80 g C. Results for a given carbon mass were lower for combustion of etched Iceland spar calcite mineral, indicating that part of the observed background of bituminous coal was probably introduced by handling the material in atmosphere prior to combustion. Using the modified combustion method, the background-corrected activity of IAEA-C5 agreed to within 2 s of the consensus value of 23.05 pMC down to a sample mass of 55 g C

Robust Mission Design Through Evidence Theory and Multi-Agent Collaborative Search

In this paper, the preliminary design of a space mission is approached introducing uncertainties on the design parameters and formulating the resulting reliable design problem as a multiobjective optimization problem. Uncertainties are modelled through evidence theory and the belief, or credibility, in the successful achievement of mission goals is maximised along with the reliability of constraint satisfaction. The multiobjective optimisation problem is solved through a novel algorithm based on the collaboration of a population of agents in search for the set of highly reliable solutions. Two typical problems in mission analysis are used to illustrate the proposed methodology