9 research outputs found
Comparing large lecture mechanics curricula using the Force Concept Inventory: A five thousand student study
The performance of over 5000 students in introductory calculus-based
mechanics courses at the Georgia Institute of Technology was assessed using the
Force Concept Inventory (FCI). Results from two different curricula were
compared: a traditional mechanics curriculum and the Matter & Interactions
(M&I) curriculum. Post-instruction FCI averages were significantly higher for
the traditional curriculum than for the M&I curriculum; the differences between
curricula persist after accounting for factors such as pre-instruction FCI
scores, grade point averages, and SAT scores. FCI performance on categories of
items organized by concepts was also compared; traditional averages were
significantly higher in each concept. We examined differences in student
preparation between the curricula and found that the relative fraction of
homework and lecture topics devoted to FCI force and motion concepts correlated
with the observed performance differences. Limitations of concept inventories
as instruments for evaluating curricular reforms are discussed.Comment: 21 pages, 4 figures, submitted to Am. J. Phys. arXiv admin note:
substantial text overlap with arXiv:1112.559
Mycoflora of the 'green water' culture system of tiger shrimp Penaeus monodon Fabricius
This study was conducted to quantify and characterize the mycoflora associated with the ‘green water’ culture system of Penaeus monodon. Samples of water, tilapia gut and mucus, and shrimp hepatopancreas from three shrimp farms were collected during 15, 30, 45 and 60 days of culture (DOC). Results showed that high fungal loads were observed in tilapia gut (total: 117–1352 colony forming unit (CFU) 5 cm hind gut−1; yeasts: 0–136 CFU 5 cm hind gut−1) and mucus (total: 12–311 CFU (5 cm2)−1; yeasts: 0–88 CFU (5 cm2)−1), while minimal fungal populations were observed in water samples (total: 0–110CFU mL−1; yeasts: 0–5 CFU ml−1). Shrimp hepatopancreas harboured a very low number of filamentous fungi (0–27 CFU 0.1 g−1) and yeasts (0–7CFU 0.1 g−1) especially at 60 DOC. The filamentous fungal isolates were dominated by Penicillium and Aspergillus species, while the yeast populations were dominated by Rhodotorula and Saccharomyces species. The dominance of these fungi on tilapia mucus and gut and their presence in the rearing water might play an important role in the overall mechanisms involved in the control of luminous Vibrio in the ‘green water’ grow-out culture of P. monodon