A Survey, Classification and Critical Review of Light-Emitting Diode Drivers

Based on a survey on over 1400 commercial LED drivers and a literature review, a range of LED driver topologies are classified according to their applications, power ratings, performance and their energy storage and regulatory requirements. Both passive and active LED drivers are included in the review and their advantages and disadvantages are discussed. This paper also presents an overall view on the technical and cost aspects of the LED technology, which is useful to both researchers and engineers in the lighting industry. Some general guidelines for selecting driver topologies are included to aid design engineers to make appropriate choices.published_or_final_versio

Storage rot fungi and seed-borne pathogens of onion

Surveys of fungi associated with postharvest deterioration of onion bulbs in four major markets in Kumasi Metropolis of the Ashanti Region of Ghana were conducted. Rotten onion bulbs obtained from the four markets (Abinchi, Anloga, Kwadaso and Central markets) were infected by five fungal species: Aspergillus niger, A. flavus, Penicillium sp., Rhizopus stolonifer and Fusarium oxysporum. Of these, A. niger and Penicillium sp. were the most frequently isolated fungi. A. flavus was the least encountered fungus. R. stolonifer and A. niger were the most pathogenic. Black mould, blue mould, soft rot, neck rot and basal plate rot were the major storage rots identified in a dry season survey in the markets. Incidences of these storage rots were higher in the wet season. Black mould enjoyed the highest incidence in all markets. Using the moist blotter method as recommended by the International Seed Testing Association (ISTA), seed-borne mycoflora of 37 samples of farmer-saved onion seeds from Bawku in the Upper East Region of Ghana were also examined. Nine different fungal species were identified and isolated from the seeds viz. A. niger, A. flavus, Penicillium sp., R. stolonifer, Fusarium oxysporum, Fusarium verticilloides, Fusarium poae, Alternaria porri and Botrytis sp. The most frequently encountered fungi were A. niger, R. stolonifer, A. flavus, Penicillium sp. and F. verticilloides with the occurrence of 33.3, 32.5, 25.8, 3.1 and 3.0%, respectively. The postharvest disease with the highest incidence in all the four markets surveyed was black mould. Some seed-borne fungi of onion were found to be associated with the onion bulb rots. Therefore, infected onion seeds could serve as inoculum source of the postharvest diseases of onion and contribute to the rot of bulbs during storage. In general, practices such as rotation, sanitation, optimum fertilization, preventive chemical applications, harvest timing and proper handling, harvesting, and storage are recommended for onion disease management.Keywords: Post-harvest, seed-borne, mycoflora, pathogenic, fung

The Role of socioeconomic factors in fertility of Umuahia women in Abia State, Nigeria

Rapid population growth arising from high fertility has been argued as being disadvantageous to the economic growth of countries especially the developing country like Nigeria. This paper examines the role of socioeconomic factors in fertility. The study elicited information from 500 women of the reproductive age of 15-49 years with Davis and Blake framework, economic and intergenerational wealth flows theories of fertility forming the theoretical orientation for the study. The mean age of the respondents and mean number of children were reported as 30.4 years and 3.6 children respectively. Respondents. age was statistically significant with fertility, while ordinal linear regression analysis showed that respondents. levels of educational and marital status were significant determinants of the number of children born by the respondents. There is a fairly high rate of fertility in the study area. Knowledge of these factors influencing fertility is a fundamental step for strategies to achieving sustainable development.Keywords: socio-economic factors, fertility, proximate variables, Abia Stat

HTR4 gene structure and altered expression in the developing lung

Background: Meta-analyses of genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) spanning the 5-hydroxytryptamine receptor 4 (5-HT4R) gene (HTR4) associated with lung function. The aims of this study were to i) investigate the expression profile of HTR4 in adult and fetal lung tissue and cultured airway cells, ii) further define HTR4 gene structure and iii) explore the potential functional implications of key SNPs using a bioinformatic approach

Correlates of genetic monogamy in socially monogamous mammals: insights from Azara's owl monkeys

Understanding the evolution of mating systems, a central topic in evolutionary biology for more than 50 years, requires examining the genetic consequences of mating and the relationships between social systems and mating systems. Among pair-living mammals, where genetic monogamy is extremely rare, the extent of extra-group paternity rates has been associated withmale participation in infant care, strength of the pair bond and length of the breeding season. This study evaluated the relationship between two of those factors and the genetic mating system of socially monogamous mammals, testing predictions that male care and strength of pair bond would be negatively correlated with rates of extra-pair paternity (EPP). Autosomal microsatellite analyses provide evidence for genetic monogamy in a pair-living primate with bi-parental care, the Azara’s owl monkey (Aotus azarae). A phylogenetically corrected generalized least square analysis was used to relate male care and strength of the pair bond to their genetic mating system (i.e. proportions of EPP) in 15 socially monogamous mammalian species. The intensity of male care was correlated with EPP rates in mammals, while strength of pair bond failed to reach statistical significance. Our analyses showthat, once social monogamy has evolved, paternal care, and potentially also close bonds, may facilitate the evolution of genetic monogamy.German Science Foundation (HU 1746/2-1); Wenner-Gren Foundation; L.S.B. Leakey Foundation;National Geographic Society; National Science Foundation (BCS-0621020, 1219368, and 1232349); the University of Pennsylvania Research Foundation; the Zoological Society of San Dieg

Simple Phosphinate Ligands Access New Zinc Clusters Identified in the Synthesis of Zinc Oxide Nanoparticles

The bottom-up synthesis of ligand-stabilised functional nanoparticles from molecular precursors is widely applied but difficult to study mechanistically. Here, we use 31P NMR spectroscopy to follow the trajectory of phosphinate ligands during the synthesis of a range of new ligated zinc oxo clusters, containing 4, 6 and 11 zinc atoms. Using an organometallic route, the clusters interconvert rapidly, and self-assemble in solution based on thermodynamic equilibria, rather than nucleation kinetics. These clusters are also identified, in situ, during the synthesis of phosphinate-capped zinc oxide nanoparticles. Unexpectedly, the ligand is sequestered to a stable Zn11 cluster during the majority of the synthesis and only becomes coordinated to the nanoparticle surface, in the final step. As well as a versatile and accessible route to new (optionally doped) zinc clusters, the findings provide a new understanding of the role of well-defined molecular precursors during the synthesis of small (2-4 nm) nanoparticles

Indoor environment & air pollutant exposure in residential buildings of Hong Kong

2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

What we observe is biased by what other people tell us: beliefs about the reliability of gaze behavior modulate attentional orienting to gaze cues

For effective social interactions with other people, information about the physical environment must be integrated with information about the interaction partner. In order to achieve this, processing of social information is guided by two components: a bottom-up mechanism reflexively triggered by stimulus-related information in the social scene and a top-down mechanism activated by task-related context information. In the present study, we investigated whether these components interact during attentional orienting to gaze direction. In particular, we examined whether the spatial specificity of gaze cueing is modulated by expectations about the reliability of gaze behavior. Expectations were either induced by instruction or could be derived from experience with displayed gaze behavior. Spatially specific cueing effects were observed with highly predictive gaze cues, but also when participants merely believed that actually non-predictive cues were highly predictive. Conversely, cueing effects for the whole gazed-at hemifield were observed with non-predictive gaze cues, and spatially specific cueing effects were attenuated when actually predictive gaze cues were believed to be non-predictive. This pattern indicates that (i) information about cue predictivity gained from sampling gaze behavior across social episodes can be incorporated in the attentional orienting to social cues, and that (ii) beliefs about gaze behavior modulate attentional orienting to gaze direction even when they contradict information available from social episodes

Consensus on level descriptors for a functional children's eating and drinking activity scale

Aim: To agree wording of level descriptors for a measure of functional outcome of children's eating and drinking. Method: An online, modified Delphi method was used to gather feedback on current level descriptor wording and generate rewording suggestions. Thirty speech and language therapists, working in a variety of settings and geographical locations, were invited to be part of the Delphi expert panel. Content analysis was used to evaluate participants' comments and develop consensus level descriptors. Consensus for acceptable wording was set at 80% agreement. Face validity was assessed using 5-point Likert scales. Results: Nineteen expert speech and language therapists (median experience 18 years) completed round one; 15 out of 19 completed round two. Level descriptor rating reached 80% agreement in two rounds. Additionally, 93% of participants agreed the scale would accurately capture change in their setting, with 87% likely to use the scale in practice. Interpretation: This study has produced agreed wording for a functional measure of eating and drinking activity suitable for use with paediatrics feeding disorders, regardless of disease aetiology, presentation, age, or setting. Potential for widespread use is supported. Further evaluation of the tool's reliability and validity is required