Estimation of ultimate stress in external FRP tendons

In a prestressed concrete beam with external tendons, the tendon stress depends on the member deformation, and it cannot be determined from section analysis alone as in the bonded case. Previous work has been mainly on the ultimate stress in unbonded steel tendons, with little on unbonded fibre-reinforced polymer (FRP) tendons. To account for the relative slip between the unbonded tendon and concrete, the ratio of the equivalent plastic hinge length to the neutral axis depth is analysed using available test results. It is found that this ratio for unbonded partially prestressed concrete (UPPC) beams with external FRP tendons can also be treated as a constant as for those with unbonded steel tendons. A simple method for evaluation of the ultimate stress in either steel or FRP external tendons is therefore proposed. After suitable modifications, the equations currently adopted by various design codes can still be used to predict the ultimate stress in external FRP tendons of UPPC beams.published_or_final_versio

Late second language learners: what predicts good outcomes

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Prediction of ultimate stress in unbonded prestressed tendons

The behaviour of prestressed concrete members with unbonded tendons is different from that of members with bonded tendons. While the behaviour of prestressed concrete beams with bonded tendons is characterised by that existing at individual sections, analysis of the entire member is necessary for beams with unbonded tendons. This paper examines various design methods for the determination of ultimate tendon stress at flexural failure of prestressed concrete beams with unbonded tendons. Two broad categories of deformation-based approaches have been identified, namely those based on the span-depth ratio together with loading type, and those based on the neutral axis depth. These methods are reviewed critically. A new design formula has been proposed in the light of the available experimental data. It is applicable not only to the conventional high-strength steel prestressing tendons, but also to those made of other materials such as fibre-reinforced polymer.published_or_final_versio

Early childhood language memory in the speech perception of international adoptees

It is as yet unclear whether the benefits of early linguistic experiences can be maintained without at least some minimal continued exposure to the language. This study compared 12 adults adopted from Korea to the US as young children (all but one prior to age one year) to 13 participants who had no prior exposure to Korean to examine whether relearning can aid in accessing early childhood language memory. All 25 participants were recruited and tested during the second week of first-semester college Korean language classes. They completed a language background questionnaire and interview, a childhood slang task and a Korean phoneme identification task. Results revealed an advantage for adoptee participants in identifying some Korean phonemes, suggesting that some components of early childhood language memory can remain intact despite many years of disuse, and that relearning a language can help in accessing such a memory. Copyright © Cambridge University Press 2009.published_or_final_versio

A strategic study of establishing the industrial needs in pattern design and technology in Mainland China

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

Service load analysis of unbonded partially prestressed concrete members

In the design of unbonded partially prestressed concrete (UPPC) members, it is necessary to estimate the stresses in steel and concrete in order to satisfy the requirements of the serviceability limit state. A numerical method has been developed to predict the response of UPPC beams under service load, and the results agree well with experimental results reported in the technical literature. A parametric study has been undertaken to evaluate the variation of stress in prestressed steel under service load as well as the ratio of length of equivalent deformation region to the neutral axis depth at critical section. Results show that this ratio is not sensitive to the variation of the combined reinforcement index. From the moment of application of load to the cracking of the beam, and until the yielding of non-prestressed steel, this ratio is fairly stable and it can be taken as a constant. With the determination of this ratio, an approximate cubic equation similar to that used for cracked section analysis of bonded partially prestressed members is established. Predictions of stresses under service load are in good agreement with available test data. © 2005 Thomas Telford Ltd.published_or_final_versio

Production benefits of childhood overhearing

The current study assessed whether overhearing Spanish during childhood helps later Spanish pronunciation in adulthood. Our preliminary report based on a subset of the data [Au et al., Psychol. Sci. 13, 238-243 (2002)] revealed that adults who overheard Spanish during childhood had better Spanish pronunciation, but not better morphosyntax, than adult learners of Spanish who had no childhood experience with Spanish. We now present data from the full sample with additional morphosyntax and pronunciation assessments, as well as measures to help rule out possible confounding prosodic factors such as speech rate, phrasing, and stress placement. Three groups of undergraduates were compared: 15 Spanish-English bilinguals (native Spanish speakers), 15 late learners of Spanish who overheard Spanish during childhood (childhood overhearers), 15 late learners of Spanish who had no regular experience with Spanish until middle or high school (typical late L2 learners). Results confirmed a pronunciation advantage for the childhood overhearers over the typical late L2 learners on all measures: phonetic analyses (VOT and degree of lenition), accent ratings (phoneme and story production), but no benefit in morphosyntax. Importantly, the pronunciation advantage did not seem attributable to prosodic factors. These findings illustrate the specificity of overhearers' advantage to phonological production. © 2003 Acoustical Society of America.published_or_final_versio

A national survey of rice (Oryza sativa L.) grain quality in Sierra Leone I: Perception of traders and consumers

As Sierra Leone approaches self-sufficiency in rice, against a backdrop of agricultural commercialization, the dynamics of the rice grain production and consumption will increasingly be driven by the quality of grains  demanded by consumers to be produced by farmers and marketed by traders in the open market. The present study was a national perception survey aimed at establishing the current status of rice grain quality based on the perspectives of traders and consumers interviewed at selected market places in four major cities across the country. In separate interviewsconducted with315 consumers and traders selected at random from 45 markets around the country, individual responses were solicited on the general interests of consumers and traders, as well as the marketing practices and aspirations for the improvement of rice grain quality in the country. Results obtained from the two surveys suggest that the priorities of rice consumers for grain quality were generally similar to those of thetraders. For example, between to 63 to 100 per cent (84 %all cities) of consumers and 69 to 100 percent (88% all cities) of traders interviewed indicated preference for imported rice, with a significant positive correlation (r = 0.78) between the two groups. Among rice products found in the market, the imported high swelling, long grain rice was shown to be preferred by both traders and consumers, due mostly to the high swelling power and non-seasonal market availability of that grain type. Other results suggest that both traders and consumers desire further improvement in grain quality, even though they do not consider this to be of high priority. The study leads to the conclusion that imported rice products are more popular than local rice products among rice traders and consumers in Sierra Leone. It is speculated that such preference might have been driven directly by the priorities of household food decisions and indirectly by the general socio-economics of food production and consumption in the country.Keywords: Rice grain quality, consumers, Sierra Leon

Clearance of technetium-99m-DTPA and HRCT findings in the evaluation of patients with Idiopathic Pulmonary Fibrosis

BACKGROUND: Clearance of inhaled technetium-labeled diethylenetriamine pentaacetate ((99m)Tc-DTPA) is a marker of epithelial damage and an index of lung epithelial permeability. The aim of this study was to investigate the role of (99m)Tc-DTPA scan in patients with Idiopathic Pulmonary Fibrosis (IPF). Our hypothesis is that the rate of pulmonary (99m)Tc-DTPA clearance could be associated with extent of High Resolution Computed Tomography (HRCT) abnormalities, cell differential of bronchoalveolar lavage fluid (BALF) and pulmonary function tests (PFTs) in patients with IPF. METHODS: We studied prospectively 18 patients (14 male, 4 female) of median age 67yr (range 55–81) with histologically proven IPF. HRCT scoring included the mean values of extent of disease. Mean values of these percentages represented the Total Interstitial Disease Score (TID). DTPA clearance was analyzed according to a dynamic study using a Venticis II radioaerosol delivery system. RESULTS: The mean (SD) TID score was 36 ± 12%, 3 patients had mild, 11 moderate and 4 severe TID. Abnormal DTPA clearance half-time (t(1/2)<40 min) was found in 17/18 (94.5%) [mean (SD) 29.1 ± 8.6 min]. TID was weakly correlated with the DTPA clearance (r = -0.47, p = 0.048) and with % eosinophils (r = 0.475, p = 0.05). No correlation was found between TID score or DTPA and PFTs in IPF patients. CONCLUSION: Our data suggest that (99m)Tc-DTPA lung scan is not well associated with HRCT abnormalities, PFTs, and BALF cellularity in patients with IPF. Further studies in large scale of patients are needed to define the role of this technique in pulmonary fibrosis

Monitoring iron chelation effect in hearts of thalassaemia patients with improved sensitivity using reduced transverse relaxation rate (RR2)

Posters - Myocardial Viability: Human Models: No. 3660Accurate MRI characterization of myocardial iron is needed to improve the diagnosis and management of thalassaemia patients with transfusional iron overload. This study aimed to demonstrate that a new transverse relaxation index, the reduced R2 (RR2) that is estimated from non-monoexponential multi-echo CPMG signal decay and sensitive to ferritin iron, could detect the myocardial iron changes immediately following 1-week iron chelation suspension in thalassaemia patients at 3T.postprin