Z-source converter based grid-interface for variable-speed permanent magnet wind turbine generators

A Z-source inverter based grid-interface for a variable-speed wind turbine connected to a permanent magnet synchronous generator is proposed. A control system is designed to harvest maximum wind energy under varied wind conditions with the use of the permanent magnet synchronous generator, diode-rectifier and Z-source inverter. Control systems for speed regulation of the generator and for DC- and AC- sides of the Z-source inverter are investigated using computer simulations and laboratory experiments. Simulation and experimental results verify the efficacy of the proposed approach.

On the design of power buffer and its applications

A power electronics-based buffer is examined in which through control of its PWM converters, the buffer-load combination is driven to operate under either constant power or constant impedance modes. A battery, incorporated within the buffer, provides the energy storage facility to facilitate the necessary power flow control. Real power demand from upstream supply is regulated under fault condition, and the possibility of voltage or network instability is reduced. The proposed buffer is also applied to a wind farm. It is shown that the buffer stabilizes the power contribution from the farm. Based on a battery cost-benefit analysis, a method is developed to determine the optimal level of the power supplied from the wind farm and the corresponding capacity of the battery storage system.

Adenovirus species C is associated with chronic suppurative lung diseases in children

Background The role of human adenoviruses (HAdVs) in chronic respiratory disease pathogenesis is recognized. However, no studies have performed molecular sequencing of HAdVs from the lower airways of children with chronic endobronchial suppuration. We thus examined the major HAdV genotypes/species, and relationships to bacterial coinfection, in children with protracted bacterial bronchitis (PBB) and mild bronchiectasis (BE). Methods Bronchoalveolar lavage (BAL) samples of 245 children with PBB or mild (cylindrical) BE were included in this prospective cohort study. HAdVs were genotyped (when possible) in those whose BAL had HAdV detected (HAdV+). Presence of bacterial infection (defined as ≥104 colony-forming units/mL) was compared between BAL HAdV+ and HAdV negative (HAdV−) groups. Immune function tests were performed including blood lymphocyte subsets in a random subgroup. Results Species C HAdVs were identified in 23 of 24 (96%) HAdV+ children; 13 (57%) were HAdV-1 and 10 (43%) were HAdV-2. An HAdV+ BAL was significantly associated with bacterial coinfection with Haemophilus influenzae, Moraxella catarrhalis, or Streptococcus pneumoniae (odds ratio [OR], 3.27; 95% confidence interval, 1.38–7.75; P = .007) and negatively associated with Staphylococcus aureus infection (P = .03). Young age was related to increased rates of HAdV+. Blood CD16 and CD56 natural killer cells were significantly more likely to be elevated in those with HAdV (80%) compared with those without (56.1%) (P = .027). Conclusions HAdV-C is the major HAdV species detected in the lower airways of children with PBB and BE. Younger age appears to be an important risk factor for HAdV+ of the lower airways and influences the likelihood of bacterial coinfection

Comparison of eight published static finite element models of the intact lumbar spine : predictive power of models improves when combined together

Finite element (FE) model studies have made important contributions to our understanding of functional biomechanics of the lumbar spine. However, if a model is used to answer clinical and biomechanical questions over a certain population, their inherently large inter-subject variability has to be considered. Current FE model studies, however, generally account only for a single distinct spinal geometry with one set of material properties. This raises questions concerning their predictive power, their range of results and on their agreement with in vitro and in vivo values. Eight well-established FE models of the lumbar spine (L1-5) of different research centres around the globe were subjected to pure and combined loading modes and compared to in vitro and in vivo measurements for intervertebral rotations, disc pressures and facet joint forces. Under pure moment loading, the predicted L1-5 rotations of almost all models fell within the reported in vitro ranges, and their median values differed on average by only 2° for flexion-extension, 1° for lateral bending and 5° for axial rotation. Predicted median facet joint forces and disc pressures were also in good agreement with published median in vitro values. However, the ranges of predictions were larger and exceeded those reported in vitro, especially for the facet joint forces. For all combined loading modes, except for flexion, predicted median segmental intervertebral rotations and disc pressures were in good agreement with measured in vivo values. In light of high inter-subject variability, the generalization of results of a single model to a population remains a concern. This study demonstrated that the pooled median of individual model results, similar to a probabilistic approach, can be used as an improved predictive tool in order to estimate the response of the lumbar spine.

Adaptations to a subterranean environment and longevity revealed by the analysis of mole rat genomes

Subterranean mammals spend their lives in dark, unventilated environments that are rich in carbon dioxide and ammonia and low in oxygen. Many of these animals are also long-lived and exhibit reduced aging-associated diseases, such as neurodegenerative disorders and cancer. We sequenced the genome of the Damaraland mole rat (DMR, Fukomys damarensis) and improved the genome assembly of the naked mole rat (NMR, Heterocephalus glaber). Comparative genome analyses, along with the transcriptomes of related subterranean rodents, revealed candidate molecular adaptations for subterranean life and longevity, including a divergent insulin peptide, expression of oxygen-carrying globins in the brain, prevention of high CO2-induced pain perception, and enhanced ammonia detoxification. Juxtaposition of the genomes of DMR and other more conventional animals with the genome of NMR revealed several truly exceptional NMR features: unusual thermogenesis, an aberrant melatonin system, pain insensitivity, and unique processing of 28S rRNA. Together, these genomes and transcriptomes extend our understanding of subterranean adaptations, stress resistance, and longevity.

Contrast and Emphasis: An Essay on the Modal Adverb Ke in Declarative Sentences [对比与强调 --- 谈陈述句中的语气副词“可”]

The data-oriented empirical research on the Chinese adverb “ke” has led to the conclusion that the semantics of the word as a modal adverb is always two-fold: it marks both “contrast” and “emphasis”. “Adversativity” as used in literature on “ke” is but one type of contrast marked by “ke”. Other types of contrast marked by “ke” in declarative sentences include: a) what is assumed by the hearer and what the truth of a matter is; b) what the sentence literally talks about and what it also implicitly conveys; and c) the original wishful nature of the stated action and its final realization. In all declarative sentences, what the adverb emphasizes is the “factuality” of what is stated. Chinese Abstract [提要] 对外汉语教学的实践表明，汉语副词“可”是教学中的难点，这跟我们对其语义内涵缺乏全面准确的认识有关。为了全面揭示副词“可”的核心语义，本作者以电视连续剧《渴望》前二十集为主要语料，并结合其他一些电视剧、电视节目以及文献里已有的语料，对出现在各种语境中的“可”进行了大量的考察和归纳性研究。研究结果表明，作为语气副词的“可”其核心语义不是单一的，它总是在标示“对比”（即“不同”）的同时表示强调。它所强调的是所述内容的“事实性”或“终然性”。由于篇幅所限，本文仅对陈述句中的语气副词“可”加以讨论

Proposing and developing the definition and conceptual framework for healthcare resilience to cope with disasters

Building healthcare resilience is an important step towards creating more resilient communities to better cope with future disasters. To date, however, there appears to be little literature on how the concept of healthcare resilience should be defined and operationalized with a conceptual framework. This article aims to build a comprehensive healthcare disaster management approach guided by the concept of resilience. Methods: Google and major health electronic databases were searched to retrieve critical relevant publications. A total of 61 related publications were included, to provide a comprehensive overview of theories and definitions relevant to disaster resilience. Results and Discussions: Resilience is an inherent and adaptive capacity to cope with future uncertainty, through multiple strategies with all hazards approaches, in an attempt to achieve a positive outcome with linkage and cooperation. Healthcare resilience can be defined as the capability of healthcare organisations to resist, absorb, and respond to the shock of disasters while maintaining the most essential functions, then recover to their original state or adapt to a new state. It can be assessed by criteria, namely: robustness, redundancy, resourcefulness; and a complex of key dimensions, namely: vulnerability and safety, disaster resources and preparedness, continuity of essential health services, recovery and adaptation. Conclusions: This new concept places healthcare organisations’ disaster capabilities, management tasks, activities and disaster outcomes together into a comprehensive whole view, using an integrated approach and establishing achievable goals.

Numerical investigation of graphene and graphene-polymer nanocomposites

This thesis is a comprehensive and deep investigation on graphene and graphene-polymer nanocomposites. It explores the strong structure-property relationships in both graphene and graphene-based polymeric nanocomposites. A number of significant conclusions, including failure mechanism in graphene, interfacial load transfer and thermal transport mechanisms in graphene-polymer nanocomposites, have been drawn through both atomistic simulations and theoretical analysis. These results can provide direct guidelines for development of new graphene-based materials and devices.

A vibrational spectroscopic study of the silicate mineral harmotome – (Ba,Na,K)1-2(Si,Al)8O16⋅6H2O – A natural zeolite

The mineral harmotome (Ba,Na,K)1-2(Si,Al)8O16⋅6H2O is a crystalline sodium calcium silicate which has the potential to be used in plaster boards and other industrial applications. It is a natural zeolite with catalytic potential. Raman bands at 1020 and 1102 cm−1 are assigned to the SiO stretching vibrations of three dimensional siloxane units. Raman bands at 428, 470 and 491 cm−1 are assigned to OSiO bending modes. The broad Raman bands at around 699, 728, 768 cm−1 are attributed to water librational modes. Intense Raman bands in the 3100 to 3800 cm−1 spectral range are assigned to OH stretching vibrations of water in harmotome. Infrared spectra are in harmony with the Raman spectra. A sharp infrared band at 3731 cm−1 is assigned to the OH stretching vibration of SiOH units. Raman spectroscopy with complimentary infrared spectroscopy enables the characterization of the silicate mineral harmotome.

Ultrathin hematite films deposited layer-by-layer on TiO2 underlayer for efficient water splitting under visible light

Ultrathin hematite (α-Fe2O3) film deposited on a TiO2 underlayer as a photoanode for photoelectrochemical water splitting was described. The TiO2 underlayer was coated on conductive fluorine-doped tin oxide (FTO) glass by spin coating. The hematite films were formed layer-by-layer by repeating the separated two-phase hydrolysis-solvothermal reaction of iron(III) acetylacetonate and aqueous ammonia. A photocurrent density of 0.683 mA cm−2 at +1.5 V vs. RHE (reversible hydrogen electrode) was obtained under visible light (>420 nm, 100 mW cm−2) illumination. The TiO2 underlayer plays an important role in the formation of hematite film, acting as an intermediary to alleviate the dead layer effect and as a support of large surface areas to coat greater amounts of Fe2O3. The as-prepared photoanodes are notably stable and highly efficient for photoelectrochemical water splitting under visible light. This study provides a facile synthesis process for the controlled production of highly active ultrathin hematite film and a simple route for photocurrent enhancement using several photoanodes in tandem.

Kirsten ras mutations in patients with colorectal cancer : the ‘RASCAL II’ study

Researchers worldwide with information about the Kirsten ras (Ki-ras) tumour genotype and outcome of patients with colorectal cancer were invited to provide that data in a schematized format for inclusion in a collaborative database called RASCAL (The Kirsten ras in-colorectal-cancer collaborative group). Our results from 2721 such patients have been presented previously and for the first time in any common cancer, showed conclusively that different gene mutations have different impacts on outcome, even when the mutations occur at the same site on the genome. To explore the effect of Ki-ras mutations at different stages of colorectal cancer, more patients were recruited to the database, which was reanalysed when information on 4268 patients from 42 centres in 21 countries had been entered. After predetermined exclusion criteria were applied, data on 3439 patients were entered into a multivariate analysis. This found that of the 12 possible mutations on codons 12 and 13 of Kirsten ras, only one mutation on codon 12, glycine to valine, found in 8.6% of all patients, had a statistically significant impact on failure-free survival (P = 0.004, HR 1.3) and overall survival (P = 0.008, HR 1.29). This mutation appeared to have a greater impact on outcome in Dukes’ C cancers (failure-free survival, P = 0.008, HR 1.5; overall survival P = 0.02, HR 1.45) than in Dukes’ B tumours (failure-free survival, P = 0.46, HR 1.12; overall survival P = 0.36, HR 1.15). Ki-ras mutations may occur early in the development of pre-cancerous adenomas in the colon and rectum. However, this collaborative study suggests that not only is the presence of a codon 12 glycine to valine mutation important for cancer progression but also that it may predispose to more aggressive biological behaviour in patients with advanced colorectal cancer.

“Privilege to Kill” phenomenon on developing countries’ roads : a preliminary case study of China

This study aims to examine the severe consequences of traffic crashes related to a special group of drivers in China, which is called the “Second Rich & Powerful Generation” (SRPG). The unique driving behaviors and attitudes of this special group are intertwined with the general cultural and social environment in China. To investigate the difference of traffic crash consequences between drivers who belong to SRPG and general driver population, injuries and fatalities in 2009, 2010, 2011 and 2012 were compared. Results consistently showed that while no significant difference was detected between these two groups in terms of injuries, fatalities per crash caused by SRPG were significantly larger than that caused by general driver population. Findings from our study clearly demonstrate the complexity of road safety issues in developing countries, and can also be used to develop road safety improvement strategies tailored to SRPG.

Assessment of the effects of maternal exposure to heatwave on birth outcomes in Brisbane, Australia

Even though heatwave events have become more frequent and intense in most regions around the world, little is known about the impact of heatwave on birth outcomes. This thesis uses a population-based study design to investigate the relationship between maternal heatwave exposure and adverse birth outcomes in Brisbane, Australia. This study found that heatwave exposure at any stage of pregnancy can be harmful to fetal growth, and further increase the risk of adverse birth outcomes. Both short- and long-term effects of heatwave on adverse birth outcomes were found. The findings in this thesis may have significant public health implications.