A Twin Study of Early-Childhood Asthma in Puerto Ricans

Background:The relative contributions of genetics and environment to asthma in Hispanics or to asthma in children younger than 3 years are not well understood.Objective:To examine the relative contributions of genetics and environment to early-childhood asthma by performing a longitudinal twin study of asthma in Puerto Rican children ≤3 years old.Methods:678 twin infants from the Puerto Rico Neo-Natal Twin Registry were assessed for asthma at age 1 year, with follow-up data obtained for 624 twins at age 3 years. Zygosity was determined by DNA microsatellite profiling. Structural equation modeling was performed for three phenotypes at ages 1 and 3 years: physician-diagnosed asthma, asthma medication use in the past year, and ≥1 hospitalization for asthma in the past year. Models were additionally adjusted for early-life environmental tobacco smoke exposure, sex, and age.Results:The prevalences of physician-diagnosed asthma, asthma medication use, and hospitalization for asthma were 11.6%, 10.8%, 4.9% at age 1 year, and 34.1%, 40.1%, and 8.5% at 3 years, respectively. Shared environmental effects contributed to the majority of variance in susceptibility to physician-diagnosed asthma and asthma medication use in the first year of life (84%-86%), while genetic effects drove variance in all phenotypes (45%-65%) at age 3 years. Early-life environmental tobacco smoke, sex, and age contributed to variance in susceptibility.Conclusion:Our longitudinal study in Puerto Rican twins demonstrates a changing contribution of shared environmental effects to liability for physician-diagnosed asthma and asthma medication use between ages 1 and 3 years. Early-life environmental tobacco smoke reduction could markedly reduce asthma morbidity in young Puerto Rican children. © 2013 Bunyavanich et al

Precise Hsu's method for analyzing the stability of periodic solutions of multi-degrees-of-freedom systems with cubic nonlinearity

This paper presents a new precise Hsu's method for investigating the stability regions of the periodic motions of an undamped two-degrees-of-freedom system with cubic nonlinearity. Firstly, the incremental harmonic balance (IHB) method is used to obtain the solution of nonlinear vibration differential equations. Hsu's method is then adopted for computing the transition matrix at the end of one period, and the precise time integration algorithm is adjusted to improve the computational precision. The stability regions of the system obtained from the precise Hsu's, Hsu's and improved numerical integration methods are compared and discussed. © 2009 Elsevier Ltd. All rights reserved.postprin

Credit supply constraints and financial policies of listed companies during the 2007–2009 financial crisis

This study examines the effects of lending constraints on the financial policies of UK publicly listed companies during the 2007–2009 financial crisis. Using a sample of 2039 publicly listed firms, the results of our analysis indicate that financial policies of firms are sensitive to variations in the supply of external finance and credit, suggesting that liquidity-constraint firms with low cash reserves suffered more at the time of the credit crunch. While managing through the potential negative effects of the financial crisis, majority of the sample companies increased the use of internal finance and deferred the payments of dividends which helped them apply effective financial policies during the crisis period. The findings of this study also document that during the crisis period, financial policies of firms were exposed to variations in the supply of finance and credit, which, by implication, posed a threat to their operations, sustainability and growth. Our findings produce awareness about the negative effects of the non-availability of external finance and credit supply to listed companies, and signify the role of different financing channels and credit system in the operations and growth of listed companies. These findings have implications for financial regulation and policy making in the UK

Provision of reinforcement in concrete solids using the generalized genetic algorithm

A generalized genetic algorithm has been developed to find the global optimal reinforcement contents for a concrete solid structure subjected to a general three-dimensional (3D) stress field. Feasible solutions were examined based on the genetic algorithm, and the heterogeneous strategy used ensures that all of the local optimal regions are searched and the most optimal reinforcement content found. The effectiveness of the proposed approach has been validated by comparing the steel contents evaluated using the present method with those obtained from other available methods. A more economic design is achieved by the proposed algorithm. The method developed provides the designer with a valuable tool for the determination of reinforcements in complicated solid concrete structures. © 2011 American Society of Civil Engineers.postprin

Investigation of a process to eco-design LED lighting products to enhance the adoption of eco-design methods and tools by industry

To date, many studies have been carried out to develop new approaches and methods to eco-design products. However, these have not been implemented and adopted by industry as much as they should. A better understanding of real-world industrial eco-design and development processes, and the eco-design tools applied during these, could inform the development of more effective and applicable eco-design methods and tools, for generic as well as for specific product categories (e.g., LED lighting products). This paper addresses this issue by describing and examining a real-world process followed to design and develop a LED lighting product by a lighting manufacturer, via case study research. The case study involved direct participatory observation to gather the data and provided new insights about the stages of the design and development process, as well as the tools applied, which were examined and discussed to inform the improvement of existing methods and tools, or the development of better new methods and tools

Inverse-designed diamond photonics

Diamond hosts optically active color centers with great promise in quantum computation, networking, and sensing. Realization of such applications is contingent upon the integration of color centers into photonic circuits. However, current diamond quantum optics experiments are restricted to single devices and few quantum emitters because fabrication constraints limit device functionalities, thus precluding color center integrated photonic circuits. In this work, we utilize inverse design methods to overcome constraints of cutting-edge diamond nanofabrication methods and fabricate compact and robust diamond devices with unique specifications. Our design method leverages advanced optimization techniques to search the full parameter space for fabricable device designs. We experimentally demonstrate inverse-designed photonic free-space interfaces as well as their scalable integration with two vastly different devices: classical photonic crystal cavities and inverse-designed waveguide-splitters. The multi-device integration capability and performance of our inverse-designed diamond platform represents a critical advancement toward integrated diamond quantum optical circuits

An integrated course for English medium of instruction teacher trainees in South Africa

Research regarding the specific needs of the L2MI teacher points to the need for developing a training course that not only ensures advanced levels of personal proficiency in the medium of instruction, but also certifies the ability to apply methodological and presentational skills that enhance and promote learning in the L2MI subject content classroom. This article describes the design and implementation of an integrated course for second language medium of instruction (L2MI) teacher trainees. Based upon the profile of effective L2MI and deriving outcomes for language,methodological and presentational skills from this, the course is both practical and functional. The hybrid model that was used for the design of the course is based on a combination of an Outcomes-based and a Backward Design model for course design and consists of six distinctive steps. The integrated course was developed within the BEd teacher-training programme and introduced for one semester. The students and the course instructor reviewed some aspects of the course and the Instructional Planafterwards.Keywords: English medium of instruction; second language medium of instruction; outcomes-based education; backward design; course design; teacher training

Delayed crack propagation in barium titanate single crystals in humid air

2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

An integrated approach for eco-design and its application in LED lighting product development

Lighting products are essential for our modern life nowadays, but they also produce high negative impacts on the environment. Although there are tools and methods available for reducing the environmental impact of lighting products, it is a challenging task to integrate them throughout the product development process. To overcome the challenge, this research developed an approach to integrate tools/methods relevant for the eco-design through product development process to reduce the environmental impact of lighting products. Six types of methods, such module design, and 30 tools, such as lifecycle assessment software packages, are considered in the integrated approach. The product specification with eco-constrains is established for implementation at each design stage to ensure the product eco-features. The approach was applied in the development of an LED table lamp which was then assessed in comparison with a benchmark LED lamp regarding environmental lifecycle impact and lighting performance. The comparative assessment results indicate that the LED lamp developed with this approach is much better than the benchmark lamp

Discrete and fuzzy dynamical genetic programming in the XCSF learning classifier system

A number of representation schemes have been presented for use within learning classifier systems, ranging from binary encodings to neural networks. This paper presents results from an investigation into using discrete and fuzzy dynamical system representations within the XCSF learning classifier system. In particular, asynchronous random Boolean networks are used to represent the traditional condition-action production system rules in the discrete case and asynchronous fuzzy logic networks in the continuous-valued case. It is shown possible to use self-adaptive, open-ended evolution to design an ensemble of such dynamical systems within XCSF to solve a number of well-known test problems