116 research outputs found
Adjusting bone mass for differences in projected bone area and other confounding variables: an allometric perspective.
No full textThe traditional method of assessing bone mineral density (BMD; given by bone mineral content [BMC] divided by projected bone area [Ap], BMD = BMC/Ap) has come under strong criticism by various authors. Their criticism being that the projected bone "area" (Ap) will systematically underestimate the skeletal bone "volume" of taller subjects. To reduce the confounding effects of bone size, an alternative ratio has been proposed called bone mineral apparent density [BMAD = BMC/(Ap)3/2]. However, bone size is not the only confounding variable associated with BMC. Others include age, sex, body size, and maturation. To assess the dimensional relationship between BMC and projected bone area, independent of other confounding variables, we proposed and fitted a proportional allometric model to the BMC data of the L2-L4 vertebrae from a previously published study. The projected bone area exponents were greater than unity for both boys (1.43) and girls (1.02), but only the boy's fitted exponent was not different from that predicted by geometric similarity (1.5). Based on these exponents, it is not clear whether bone mass acquisition increases in proportion to the projected bone area (Ap) or an estimate of projected bone volume (Ap)3/2. However, by adopting the proposed methods, the analysis will automatically adjust BMC for differences in projected bone size and other confounding variables for the particular population being studied. Hence, the necessity to speculate as to the theoretical value of the exponent of Ap, although interesting, becomes redundant
Surface bone-like apatite characteristic and the osteoinduction of calcium phosphate ceramics
No full textThe effect of bone-like apatite characteristics to osteoinduction was investigated. Samples of biphasic calcium phosphate ceramics with different surface characteristics were studied. The results showed that the surface bone-like apatite characteristics could influence the osteoinductivity of the materials. Bone like apatite manipulated by protein molecules showed better osteoinductivity and cell activity than that without proteins.link_to_subscribed_fulltex
When high achievers and low achievers work in the same group: The roles of group heterogeneity and processes in project-based learning
No full textBackground. There has been an ongoing debate about the inconsistent effects of heterogeneous ability grouping on students in small group work such as project-based learning. Aim. The present research investigated the roles of group heterogeneity and processes in project-based learning. At the student level, we examined the interaction effect between students' within-group achievement and group processes on their self-and collective efficacy. At the group level, we examined how group heterogeneity was associated with the average self- and collective efficacy reported by the groups. Sample. The participants were 1,921 Hong Kong secondary students in 367 project-based learning groups. Method. Student achievement was determined by school examination marks. Group processes, self-efficacy and collective efficacy were measured by a student-report questionnaire. Hierarchical linear modelling was used to analyse the nested data. Results. When individual students in each group were taken as the unit of analysis, results indicated an interaction effect of group processes and students' within-group achievement on the discrepancy between collective- and self-efficacy. When compared with low achievers, high achievers reported lower collective efficacy than self-efficacy when group processes were of low quality. However, both low and high achievers reported higher collective efficacy than self-efficacy when group processes were of high quality. With 367 groups taken as the unit of analysis, the results showed that group heterogeneity, group gender composition and group size were not related to the discrepancy between collective- and self-efficacy reported by the students. Conclusions. Group heterogeneity was not a determinant factor in students' learning efficacy. Instead, the quality of group processes played a pivotal role because both high and low achievers were able to benefit when group processes were of high quality. © 2008 The British Psychological Society.link_to_subscribed_fulltex
Processing Order and Quantity Information in the Healthy and Dysfunctional Brain: A TMS Study
No full textFluid flow and combined free and forced convective heat transfer in a rotating curved circular tube (part 1)
No full textA theoretical study is made of the combined free and forced convective heat transfer and fluid flow in a rotating curved circular tube for the fully developed flow with the thermal boundary condition of constant heat flux per length of tube. The pertubation technique is employed for both 'positive' rotation and 'negative' rotation. And both heating and cooling are involved in the analyses. Based on the first order solution, the interaction among centrifugal force due to the curvature of the tube, Coriolis force contributed by the rotating of the tube and the centrifugal-type buoyancy force caused by temperature-induced density variation of the fluid in rotating field and their effects on the secondary flow and temperature distribution are discussed in some details. The second order solution, local and mean friction factors and Nusselt numbers will be given later in Part 2.link_to_subscribed_fulltex
Early screening of developmental dysplasia of hip by acoustical technique
No full text2001-2002 > Academic research: refereed > Publication in refereed journalbcmaVersion of RecordPublishedVoR allowe
Stability analysis of T-S fuzzy-model-based control systems using fuzzy Lyapunov function
No full textAuthor name used in this publication: F. H. F. LeungCentre for Signal Processing, Department of Electronic and Information EngineeringRefereed conference paper2007-2008 > Academic research: refereed > Refereed conference paperVersion of RecordPublishedVoR allowe
An improved differential evolution and its industrial application
No full textAuthor name used in this publication: Lai, Johnny Chung YeeAuthor name used in this publication: Leung, Frank Hung Fat2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishedC
Comparison of radiography and magnetic resonance imaging in the detection of injuries after paediatric elbow trauma
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