The instructional benefits of dynamic visualizations in the acquisition of basketball tactical actions

Recent studies exploring the effects of dynamic visualizations on learning compared with static visualizations have yielded mixed results. Procedural motor learning is one of the few fields in which dynamic representations have shown to be effective. Many of the studies have suggested that this advantage is mainly due to the activation of the “mirror‐neuron system.” This study explores this explanation in physical education domain and analysed the effects of instructional media (video vs. photographs), showing tactical actions in basketball, on learning outcomes (i.e., game understanding and game performance), cognitive load (i.e., mental effort invested and estimated difficulty), and attitudes (i.e., attention, enjoyment, engagement, and challenge) in secondary school students. For all of the indicators, the results show that learning from video was more effective than learning from photographs. These findings have implications for the effective design of instructional media and provide confirmation of the superiority of video for teaching tactical actions involving the entire body.     

Improvement of catalytic stability and carbon resistance in the process of CO2 reforming of methane by CoAl and CoFe hydrotalcite-derived catalysts

The CoAl-LDH and CoFe-LDH hydrotalcite-like compounds (LDH = Layered Double Hydroxides named also hydrotalcite), were successfully synthesized following co-precipitation method at pH = 12. A several characterization techniques including TGA, ICP, XRD, N₂ adsorption and desorption, H₂-TPR, O₂-TPO, SEM-EDX and TEM, were utilized to determine the structure function relationship for the obtained catalysts. These catalysts were evaluated in CO₂ reforming of methane under continuous flow with CH₄/CO₂ ration equal to 1, at atmospheric pressure and a temperature range between 400 and 700 °C.The iron addition to the cobalt showed improved resistance to coke deposition while a slight decrease in methane conversion was observed compared to CoAl_cal-R catalyst (cal = after calcination and R = after reduction) derived from CoAl-LDH precursor.     

Structure-Activity Relationship Analysis of Dialkyltin (IV) Dicarboxylates as Catalysis for the Crosslinking of α, ω-Dihydroxy-Polydimethylsiloxane

Silicon - A number of homologous dialkyl tin (IV) dicarboxylate (organotin compounds), varying with respect to the length of alkyl groups have been studied with respect to their catalytic activity...     

Broad substrate specificity of ketoreductases derived from modular polyketide synthases

Recombinant ketoreductase (KR) domains derived from antibiotic-producing modular polyketide synthases (PKSs) have been examined as potential catalysts for the enantioselective reduction of non-polyketide substrates. KR domains from two modular PKSs show significant activity toward alternative substrates, particularly those that incorporate cyclohexyl moieties. Through site-directed mutagenesis of the amino acid motifs previously implicated in stereocontrol by KRs, we have identified mutants with improved activity toward such compounds. These results suggest that PKS KRs could potentially be used as biotransformation catalysts for the production of chiral alcohols.     

Ketoreduction in mycolactone biosynthesis: insight into substrate specificity and stereocontrol from studies of discrete ketoreductase domains in vitro

Mycolactone, a polyketide toxin responsible for the extensive tissue destruction seen in Buruli ulcer, is assembled on a modular polyketide synthase (PKS). Despite operating on structurally different intermediates during synthesis, many of the ketoreductase (KR) domains of the mycolactone (MLS) PKS have identical sequences. This suggests that these enzymes might exhibit an unusually high level of substrate promiscuity. However, we show here that when recombinant mycolactone KR domains are tested with a range of surrogate substrates, their specificity closely matches that of KR domains derived from other PKS systems. In addition, our findings reinforce the role of substrate tethering for achieving stereochemical control in modular PKSs by affecting the delicate energetics of ketoreduction.     

Torsades de pointes: a case with multiple variables

PURPOSE: The human medulloblastoma cell line D283 Med (4-HCR), a line resistant to 4-hydroperoxycyclophosphamide (4-HC), displays enhanced repair of DNA interstrand crosslinks induced by phosphoramide mustard. D283 Med (4-HCR) cells are cross-resistant to 1,3-bis(2-chloroethyl)- -nitrosourea, but partial sensitivity is restored after elevated levels of O6-alkylguanine-DNA alkyltransferase (AGT) are depleted by O6-benzylguanine (O6-BG). Studies were conducted to define the activity of 4-HC and 4-hydroperoxydidechlorocyclophosphamide against D283 Med (4-HCR) after AGT is depleted by O6-BG. METHODS: Limiting dilution and xenograft studies were conducted to define the activity of 4-HC and 4-hydroperoxydidechlorocyclophosphamide with or without O6-BG. RESULTS: The activity of 4-HC and 4-hydroperoxydidechlorocyclophosphamide against D283 Med (4-HCR) was increased after AGT depletion by O6-BG preincubation. Similar studies with Chinese hamster ovary cells, with or without stable transfection with a plasmid expressing the human AGT protein, revealed that the AGT-expressing cells were significantly less sensitive to 4-HC and 4-hydroperoxydidechlorocyclophosphamide. Reaction of DNA with 4-HC, phosphoramide mustard, or acrolein revealed that only 4-HC and acrolein caused a decrease in AGT levels. CONCLUSIONS: We propose that a small but potentially significant part of the cellular toxicity of cyclophosphamide in these cells is due to acrolein, and that this toxicity is abrogated by removal of the acrolein adduct from DNA by AGT.     

Characterizing user‐perceived impairment events using end‐to‐end measurements

Measures of quality of service (QoS) must correlate to end‐user experience. For multimedia services, these metrics should focus on the phenomena that are observable by the end‐user. Metrics such as delay and loss may have little direct meaning to the end‐user because knowledge of specific coding and/or adaptive techniques is required to translate delay and loss to the user‐perceived performance. Impairment events, as defined in this paper, are observable by the end‐users independent of coding, adaptive playout or packet loss concealment techniques employed by their multimedia applications. Time between impairments and duration of impairments are metrics that are easily understandable by a network user. Methods to detect these impairment events using end‐to‐end measurements are developed here. In addition, techniques to identify Layer 2 route changes and congestion events using end‐to‐end measurements are also developed. These are useful in determining what caused the impairments. End‐to‐end measurements were conducted for about 26 days on 9 different node pairs to evaluate the developed techniques. Impairments occurred at a high rate on the two paths on which congestion events were detected. On these two paths, congestion occurred for 6–8 hours during the day on weekdays. Impairments caused by route changes were rare but lasted for several minutes. Copyright © 2005 John Wiley & Sons, Ltd.     

Bacteriocins: Recent Trends and Potential Applications

In the modern era, there is great need for food preservation in both developing and developed countries due to increasing demand for extending shelf life and prevention of spoilage of food material. With the emergence of new pathogens and ability of micro-organisms to undergo changes, exploration of new avenues for the food preservation has gained importance. Moreover, awareness among consumers regarding harmful effects of chemical preservatives has been increased. Globally, altogether there is increasing demand by consumers for chemical-free and minimal processed food products. Potential of bacteriocin and its application in reducing the microbiological spoilages and in the preservation of food is long been recognized. Bacteriocins are normally specific to closely related species without disrupting the growth of other microbial populations. A number of applications of bacteriocin have been reported for humans, live stock, aquaculture etc. This review is focused on recent trends and applications of bacteriocins in different areas in addition to their biopreservative potential.