A prototype multimedia program, Multimedia and Mental Models in Chemistry (4M:CHEM), was developed to facilitate student learning in the classroom. 4M:CHEM utilizes a computer split-screen design to show simultaneous videos of real experiments, molecular-level animations of these experiments, real time graphs of macroscopic properties or structural diagrams, and chemical equations. These four windows can be shown individually or in any combination. When multiple windows are activated, actions in each are synchronized. These synchronized views of chemical phenomena may be paused and restarted in order to aid discussions of connections between and limitations of macroscopic, microscopic, and symbolic representations. The prototype program involves 32 experiments dealing with physical, gaseous, solution, and heterogeneous equilibria. Both qualitative and quantitative experiments are included to assist students in building chemical understanding and intuition as well as enhancing their quantitative problem solving abilities. An initial assessment of 4M:CHEM in two lecture sections for two one-hour presentations showed an increase in students' understanding of characteristics of systems at equilibrium and a marked decrease in misconceptions of chemical equilibrium.

1. Studies of mesic temperate and tropical rivers suggest an important role for floodplain habitats as nursery areas for larval and juvenile fishes. In arid-land rivers the extent and duration of flooding is diminished and habitats and resources used by larval fishes are poorly known. Our study documented habitat and resource use of larval fishes in the Rio Grande, New Mexico, an arid-land river. 2. Spatial and temporal distribution of larval and juvenile fishes and their inferred microhabitat preferences were studied during spring, summer and autumn, 2003. Stable carbon ( 13 C : 12 C) and nitrogen ( 15 N : 14 N) isotope ratios were measured to identify nutrient sources and characterise trophic positions of young-of-year fishes in this system. 3. Some fishes recruited during high flows (in spring), whereas others recruited during low-flow periods in late summer. Regardless of the timing of reproduction, microhabitats with lower current velocity and higher temperature appeared to serve as vital nursery grounds for Rio Grande fishes. Ephemeral backwaters and disconnected side channels held the highest abundance and diversity of larvae and juveniles. 4. Stable isotope analyses revealed that fish larvae obtained carbon predominately from algal production in early summer, but used organic carbon derived from emergent macrophytes as river discharge decreased in mid-summer. This shift may have been facilitated by microinvertebrate prey that grazed down edible algae and then switched to macrophytes in mid-summer. Nitrogen isotope ratios did not differ among species or early life stages, suggesting that larval and juvenile fishes use similar food resources, especially when restricted to isolated pools in summer.

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The introduction of a comprehensive tobacco education curriculum in DS and DHS programs could further improve students' perceptions and attitudes and provide knowledge and clinical experience which would lead to the incorporation of TUC into subsequent professional practice.

SummaryBackgroundThe risks/benefits balance of hormone replacement therapy (HRT) is controversial. The aim of this study was to assess the periodontal status of a postmenopausal women group receiving HRT and to determine the effects of HRT on clinical measures of periodontal disease.Material/MethodsNinety-one postmenopausal women, 52 taking HRT (HRT+) and 39 not taking HRT (HRT−), completed the study. Clinical parameters measured included visible supragingival plaque, probing pocket depth (PD) and clinical attachment level (CAL). Gingival status was recorded as gingival bleeding on probing (BOP). Previous oral contraceptive use and current and past smoking status were also assessed.ResultsData indicated that PD and CAL were not significantly different between HRT+ patients and HRT− patients (P=0.8067 and P=0.1627, respectively). The HRT+ group exhibited significantly lower visible plaque levels compared to the control group (P<0.0001). The percentage of gingival sites with positive BOP was significantly lower in the HRT+ group compared to the HRT− group (34.85% vs. 65.15%; P=0.0007). Plaque accumulation was also tested in ANCOVA as a possible explanatory variable for the differences observed in gingival bleeding. The ANCOVA showed no significant differences in gingival bleeding between HRT+ and HRT− women (P=0.4677). No significant differences in past smoking status and oral contraceptive use were detected between HRT+ and HRT− women (P=0.9999 and P=0.0845, respectively).ConclusionsThese findings indicated that long-term HRT was not associated with relevant effects on periodontal status and clinical measures of periodontal disease, thus suggesting that HRT may not confer protection against periodontitis in postmenopausal women.