Generalization strategies in finding the nth term rule for simple quadratic sequences

In this study, we identify ways in which a sample of 18 graduates with mathematics-related first degrees found the nth term for quadratic sequences from the first values of a sequence of data, presented on a computer screen in various formats: tabular, scattered data pairs and sequential. Participants’ approaches to identifying the nth term were recorded with eye-tracking technology. Our aims are to identify their strategies and to explore whether and how format influences these strategies. Qualitative analysis of eye-tracking data offers several strategies: Sequence of Differences, Building a Relationship, Known Formula, Linear Recursive and Initial Conjecture. Sequence of Differences was the most common strategy, but Building a Relationship was more likely to lead to the right formula. Building from Square and Factor Search were the most successful methods of Building a Relationship. Findings about the influence of format on the range of strategies were inconclusive but analysis indicated sporadic evidence of possible influences

Vitamin A policies need rethinking

<p>This paper presents evidence that the impact of semi-annual megadoses of vitamin A to young children no longer has much if any impact on young child mortality. This is probably due to changes in disease patterns, with measles and diarrhea, the only diseases known to be linked to vitamin A deficiency, no longer linked to as many child deaths. </p

Standardizing the evaluation of community-based conservation success (Ecological Applications)

<p><a>Community-based conservation, which strives to simultaneously improve nature conservation and alleviate poverty, must provide </a><a>biological and socio-economic benefits that are linked through effective resilience mechanisms. </a>To date, few community-based conservation initiatives have published comprehensive assessments that track performance in these elements of success. <a>With 45% of the world’s protected areas in co-management with local communities, standardized measures to effectively evaluate the dual goals of community-based conservation are needed. </a>To address this need, we developed SPECCS, a user-friendly Standardized Protocol for Evaluating Community Conservation Success <a>that incorporates an appraisal of data quality to responsibly assess progress over time or to compare effectiveness among different initiatives (</a><a href="http://www.calgaryzoo.com/why-we-matter/our-approach">www.calgaryzoo.com/why-we-matter/our-approach</a>). In <strong>Brichieri-Colombi et al. </strong>Standardizing the evaluation of community-based conservation success, <i>Ecological Applications,</i> we illustrate SPECCS’s use by evaluating the Wechiau Community Hippo Sanctuary (WCHS) of northern Ghana 10 and 20 years after its inception. Presented here are additional (raw) data used to evaluate the WCHS. For additional data and more information, please see our published works.</p

Regulated Expression of a Cytokinin Biosynthesis Gene <i>IPT</i> Delays Leaf Senescence and Improves Yield under Rainfed and Irrigated Conditions in Canola (<i>Brassica napus</i> L.)

<div><p>Delay of leaf senescence through genetic modification can potentially improve crop yield, through maintenance of photosynthetically active leaves for a longer period. Plant growth hormones such as cytokinin regulate and delay leaf senescence. Here, the structural gene (<i>IPT</i>) encoding the cytokinin biosynthetic enzyme isopentenyltransferase was fused to a functionally active fragment of the <i>AtMYB32</i> promoter and was transformed into canola plants. Expression of the <i>AtMYB32xs::IPT</i> gene cassette delayed the leaf senescence in transgenic plants grown under controlled environment conditions and field experiments conducted for a single season at two geographic locations. The transgenic canola plants retained higher chlorophyll levels for an extended period and produced significantly higher seed yield with similar growth and phenology compared to wild type and null control plants under rainfed and irrigated treatments. The yield increase in transgenic plants was in the range of 16% to 23% and 7% to 16% under rainfed and irrigated conditions, respectively, compared to control plants. Most of the seed quality parameters in transgenic plants were similar, and with elevated oleic acid content in all transgenic lines and higher oil content and lower glucosinolate content in one specific transgenic line as compared to control plants. The results suggest that by delaying leaf senescence using the <i>AtMYB32xs::IPT</i> technology, productivity in crop plants can be improved under water stress and well-watered conditions.</p></div

Seed yield at the Hamilton field experiment.

<p>Yield Statistics: Standard error of difference of means (SED)- 0.366, LSD (5%); least significant difference- 0.735, P value <0.001.</p><p>* Yield significantly different in transgenic line than corresponding null.</p><p>* Yield significantly different in transgenic line than corresponding null.</p><p>Yield increase (%) of transgenic lines 6.6.38 and 6.6.40 over corresponding null control 6.2 is shown. Yield increase (%) of transgenic line 7.1.38 over corresponding null control 7.6 is shown.</p><p>Seed yield at the Hamilton field experiment.</p

NDVI in canola genotypes under irrigated and rainfed field conditions.

<p><b>A</b>. NDVI was calculated from data taken at different time points during the reproductive growth using crop circle. <b>B,C</b>. NDVI for transgenic (6.6.38, 6.6.40 and 7.1.38), null control (6.2 and 7.6) and WT at 174 days after sowing under irrigated and rainfed treatments. Data is mean ± SD. Bars with different letters indicate significant difference at P<0.05. DAP, days after planting; NDVI, Normalised difference vegetation index, NC, null control; T, transgenic, WT, wild type.</p

Leaf senescence in plants of canola genotypes grown under controlled environment conditions.

<p><b>A</b>. Transgenic and wild type plants. <b>B</b>. Detached leaf assay on leaves of transgenic (6.6.38, 6.6.40 and 7.1.38), WT and null control (6.2 and 7.6) plants was done. Plants were grown for five weeks, leaves from similar position were picked and kept on moist filter paper for one week. NC, null control; T, transgenic, WT, wild type.</p

Senescence progression in canola genotypes near maturity under field conditions.

<p><b>A</b>. Basal plant parts. <b>B</b>. Crop canopy in experimental plots. Pictures were taken at 174 DAP. DAP, days after planting; NC, null control; T, transgenic, WT, wild type.</p

SPAD chlorophyll levels in canola genotypes under field conditions.

<p><b>A</b>. Decrease in chlorophyll level in transgenic (6.6.38, 6.6.40 and 7.1.38), null control (6.2 and 7.6) and WT during ripening period; onset of flowering (150 DAP) till near to maturity (178 DAP). <b>B</b>. Chlorophyll level in genotypes at 178 days after sowing. Data is mean ± SD. Bars with different letters indicate significant difference at P<0.05. NC, null control; T, transgenic, WT, wild type.</p

Additional file 1: of Comparison of two related lines of tauGFP transgenic mice designed for lineage tracing

Figure S1. Confocal microscope with environmental chamber. (a) The Leica DMIRB/E inverted confocal microscope is shown together with the stage-mounted environmental chamber and some of the equipment required to maintain the correct temperature and gas phase within the chamber. (b) Side view of the environmental chamber with a culture dish on the heated stage. The flow of carbon dioxide from the gas cylinder to the environmental chamber was controlled by an infrared gas monitor to ensure that the gas mixture inside the environmental chamber was maintained at 5% CO2 in air. Embryos were cultured in drops of culture medium under liquid paraffin oil in a WillCo thin glass-bottomed culture dish on the heated stage. Time-lapse images of the embryos were acquired every 15 or 30 min in both fluorescent (FITC) and transmitted light modes for up to 24 h. Abbreviations: EC, environmental chamber; GC, gas cylinder; GM, gas monitor; HS, heated stage; HSC, heated stage controller. Figure S2. Comparison of sizes of E14.5 tauGFP-positive and tauGFP-negative fetuses from two crosses. (a-d) Comparisons of tauGFP-positive and tauGFP-negative fetal sizes using a 2-way analysis of variance (ANOVA) to allow for variation among litters. The graphs show fetal mass (a) and crown-rump length (b) for the TgTP6.4 Tg/− female × TgTP6.4 Tg/− male cross plus fetal mass (c) and crown-rump length (d) for the TgTP6.4 Tg/- female × TgTP6.4 −/− male cross. Each point represents a single fetus and fetuses are arranged by litters. Sexes were not distinguished and only litters with both tauGFP-positive and tauGFP-negative fetuses were included. Numbers of fetuses, means and P-values are shown. (e-h) Differences between within-litter means are shown for fetal mass and crown-rump length for tauGFP-positive and tauGFP-negative fetuses in each cross. P-values are shown for paired t-tests. Abbreviations: GFP-ve, tauGFP-negative; GFP + ve, tauGFP-positive. Figure S3. Relationship between mean stripe width and the percentage of tauGFP-positive cells in TgTP6.4 Tg/− adrenal cortices. (a) The uncorrected mean tauGFP-positive stripe width for 27 TgTP6.4 Tg/− adrenal glands varied widely. It was close to 2% of the adrenal circumference when the percentage of tauGFP-positive cells in the adrenal cortex was low but it was positively correlated with the percentage of tauGFP-positive cells. The Spearman correlation coefficient (rs) is shown. This positive correlation is likely to be because stripes may comprise several adjacent coherent clones of cells and the average number of tauGFP-positive clones per tauGFP-positive stripe will increase with the percentage of tauGFP-positive cells in the adrenal cortex. (b) The corrected mean tauGFP-positive stripe width was not significantly correlated with the percentage of tauGFP-positive cells so allows comparisons among adrenals with different percentages of tauGFP-positive cells. The observed (uncorrected) mean tauGFP-positive stripe number was corrected by dividing it by the correction factor 1/(1-p), where p is the proportion of tauGFP-positive cells around the circumference as explained in the Methods. Figure S4. Age has no effect on percentage of tauGFP-positive cells or corrected stripe number in mosaic adrenal cortices of TgTP6.3 Tg/− and TgTP6.4 Tg/− mice. (a-d) There were no significant differences among age groups for the % tauGFP-positive cells in the adrenal cortex for (a) TgTP6.3 Tg/- females (b) TgTP6.3 Tg/- males (c) TgTP6.4 Tg/- females or (d) TgTP6.4 Tg/- males. Mice were grouped into three or more age groups and analysed by the Kruskal-Wallis test (KW test). (e-h) There were also no significant positive correlations between age and the % tauGFP-positive cells in the adrenal cortex for any of the four groups. Spearman correlation coefficients (rs) are shown. (i-l) There were no significant differences among age groups for the corrected stripe number (tauGFP-positive stripes plus tauGFP-negative stripes) in the adrenal cortex for any sex and genotype combination. Mice were grouped into three or more age groups and analysed by the Kruskal-Wallis test (KW test) or 1-way ANOVA. (m-p) There were also no significant positive correlations between age and the corrected stripe number in the adrenal cortex for any sex and genotype combination. Pearson correlation coefficients (r) and the linear regression lines are shown but no lines differed significantly from horizontal. N = number of adrenal glands; one adrenal gland was analysed per mouse. Table S1. FACS analysis of fetal brains. (PDF 599 kb