Diagnosis of Major Organic Acidurias in Children: Two Years Experience at a Tertiary Care Centre

Organic acid disorders are inherited metabolic disorders in which organic acids accumulate in tissues and biological fluids of affected individuals. Classical organic acidurias include methylmalonic aciduria, propionic aciduria, isovaleric aciduria and maple syrup urine disease (MSUD). They are considered the most frequent metabolic disorders among severely ill children. Patients frequently present with acute symptoms early in life. 420 cases clinically suspected to have organic aciduria, with upper age limit of 12 years for a 2-year period (January 2007–December 2008) were enrolled into this study. Metabolic acidosis and neurological symptoms were the most common signs. Screening tests and thin layer chromatography were done for detection of organic acidurias. Identification and quantitation of organic acids in urine and quantification of amino acids in blood were done by high performance liquid chromatography. Out of 420 patients, 45 patients (10.7%) were found to have organic acidurias. 15 cases of methylmalonic aciduria, 16 cases of propionic aciduria, 13 cases of MSUD, and one case of isovaleric aciduria were diagnosed. Results demonstrate the importance of testing for organic acidurias. Since organic aciduria may cause irreversible brain damage if not treated, we recommend selective screening amongst severely ill children despite implied extra costs.     

1, 2, 3, 4: Infusing Quantitative Literacy into Introductory Biology

Biology of the twenty-first century is an increasingly quantitative science. Undergraduate biology education therefore needs to provide opportunities for students to develop fluency in the tools and language of quantitative disciplines. Quantitative literacy (QL) is important for future scientists as well as for citizens, who need to interpret numeric information and data-based claims regarding nearly every aspect of daily life. To address the need for QL in biology education, we incorporated quantitative concepts throughout a semester-long introductory biology course at a large research university. Early in the course, we assessed the quantitative skills that students bring to the introductory biology classroom and found that students had difficulties in performing simple calculations, representing data graphically, and articulating data-driven arguments. In response to students'' learning needs, we infused the course with quantitative concepts aligned with the existing course content and learning objectives. The effectiveness of this approach is demonstrated by significant improvement in the quality of students'' graphical representations of biological data. Infusing QL in introductory biology presents challenges. Our study, however, supports the conclusion that it is feasible in the context of an existing course, consistent with the goals of college biology education, and promotes students'' development of important quantitative skills.     

Can districts keep good teachers in the schools that need them most?

This study investigates how school demographics and their interactions with policies affect the mobility behaviors of public school teachers with various human capital characteristics. Using data from North Carolina from 1995 to 2006, it finds that teachers’ career stage and human capital investments dominate their decisions to leave public school teaching and school demographic characteristics play a dominant role in intra-system sorting. Schools serving at-risk children struggle to attract and retain teachers with desirable observable characteristics. We find evidence to suggest that across-the-board school-based pay-for-performance policies have small but significant associations with mobility decisions and appear to exacerbate inequities in the distribution of teacher qualifications.     

Cognitive Load Theory as a Tool for Expertise Development

This special issue is dedicated to recentdevelopments within cognitive load theory (CLT)and identifies some instructional implicationsof the interaction between informationstructures and cognitive architecture. Thepresent article discusses the different studiesin this special issue. An important conclusionis that recent CLT research recognizes thelearners' level of expertise as an importantfactor mediating the relation between cognitivearchitecture, information structures, andlearning outcomes. In this context, we discussthe role of expertise in CLT research and therole of CLT in expertise research. Based onthis discussion, the use of CLT as a tool todevelop expertise is identified as a verypromising approach.     

Modelling impact of dredging and dumping in ebb-flood channel systems

For a channel-shoal system in a funnel-shaped basin the impact of dredging and dumping is investigated using a complex process-based model. First, the residual flow and sediment transport circulations are analysed for the channel-shoal pattern, which has emerged after a long-term model simulation. Results are compared to the Western Scheldt estuary, which forms the inspiration for this study. Subsequently, different dredge and dump scenarios are modelled, according to a conceptual model, in which ebb-and flood-channels and enclosed shoals form morphodynamic units (cells) with their own sediment circulation. Model results show that dumping sediment in a channel further reduces the channel depth and induces erosion in the opposite channel, which enhances tilting of the cross-section of the cell and eventually can lead to the degeneration of a multiple channel system into a single channel. The impact of different dredging and dumping cases agrees with results from a stability analysis. This means that this type of model applied to a realistic geometry can potentially be used for better prediction of the impact of human interventions.