3,378 research outputs found
Method and system to stabilize and preserve iron artifacts
A method, system and device to use a dilute alkaline solution held at sub-critical temperature and pressure conditions to remove rapidly chloride ions from corroded iron artifacts
Analysis of Free Sugars and Chlorophyll in Spinach From A Local Retail Market
The accuracy (percentage recovery) and precision (coefficient of variation or CV) of extraction and an anion-exchange HPLC method using amperometric detection for measurement of free sugars in spinach were determined. Five samples of fresh spinach leaves were extracted and analyzed by the HPLC method for glucose, fructose and sucrose. Different amounts (0.093 to 0.453% of spinach, wet basis or WB) of each of the latter sugars were added to each of five spinach samples and these spiked samples were analyzed in a similar manner as the unspiked samples. The average percentage recoveries of glucose, fructose and sucrose were respectively, 106.6, 101.5 and 106.0. CV\u27s of percentage recoveries for the five spiked samples were 7.8% for glucose, 6.8% for fructose and 2.8% for sucrose.
The reported levels of total sugars in market fresh spinach in Europe range from 0.1 to 1.5% (WB) but have not been determined in the U.S.A. The recognition threshold for sweetness of sugars is approximately in the middle of the reported concentration range of sugars in spinach; thus the higher concentration ranges of sugars probably add a desirable sweetness to the fresh spinach. If levels of the sugars in fresh spinach in the U.S.A. were known, then a basis for assessment of sweetness to the flavor of such spinach could be made. Therefore, market fresh spinach samples in Knoxville, TN, were collected from four markets weekly for an eight week period in the spring of 1995. This spinach, which is shipped in primarily from California, should be fairly representative of that consumed by Southeastern U.S. customers during that time of the year. Sugar (glucose, fructose and sucrose) levels, moisture content, and chlorophyll a and b levels were also measured. On a dry basis (DB) , the fresh spinach contained 0.09 - 0.40% glucose, 0.02 - 0.20% fructose, 0.13 - 0.37% sucrose, 0.53 - 0. 78% chlorophyll a and 0.18 - 0.25% chlorophyll b the fresh spinach also contained from 90.0 - 91. 7% moisture. Spinach from one market had (p\u3c0.05) higher levels of sucrose but lower moisture and chlorophyll contents than spinach from the other three markets. All spinach samples were dark green in color with crisp texture and were acceptable as fresh samples
Exploring Financial Literacy and Overconfident Investor Behavior
This study examined the factors predicting overconfidence in U.S. investors and the relationship between overconfidence and seeking financial advice. This study adopted a quantitative research method using the 2018 NFCS Investor Survey data to explore the relationship between financial literacy and investor behavior in the U.S. stock market. Theories in financial literacy and overconfident behavior are combined to identify factors that predict overconfident behavior in U.S. investors. A logistic regression model was utilized to understand the relationship between financial literacy, demographics, and overconfident investor behavior. The results show a positive relationship between overconfident behavior and portfolio value, seeking financial advice, and conducting research activity. Results also showed that overconfidence is higher in male investors, younger investors, and investors with lower incomes. These findings are useful to individuals and corporations across several applications. Individuals can increase self-awareness regarding their own behaviors to identify certain biases, such as overconfidence, to help them avoid making large financial mistakes. Financial advisors can utilize these findings to become more aware of their clients that are likely to demonstrate overconfident behavior and help them mitigate these risks. Government entities can incorporate financial literacy programs that will establish baseline financial literacy competency in primary and secondary education programs
Derivation of a dynamic model of the kinetics of nitrogen uptake throughout the growth of lettuce : calibration and validation
A kinetic model of nitrogen (N) uptake throughout growth was developed for lettuce
cultivated in nutrient solution under varying natural light conditions. The model couples
nitrogen uptake with dry matter accumulation using a two-compartment mechanistic
approach, incorporating structural and non-structural pools. Maximum nitrogen uptake
rates are assumed to decline with shoot dry weight, to allow for the effects of plant
age. The model was parameterized using data from the literature, and calibrated for
differences in light intensity using an optimization algorithm utilizing data from three
experiments in different growing seasons. The calibrated model was validated against
the data from two independent experiments conducted under different light conditions.
Results showed that the model made good predictions of nitrogen uptake by plants from
seedlings to maturity under fluctuating light levels in a glasshouse. Plants grown at a
higher light intensity showed larger maximum nitrogen uptake rates, but the effect of
light intensity declined towards plant maturity
Fatal Distraction? A Comparison of the Cell-phone Driver and the Drunk Driver
We used a high-fidelity driving simulator to compare the performance of cell-phone drivers with drivers who were legally intoxicated from ethanol. When drivers were conversing on either a hand-held or hands-free cell-phone, their reactions were sluggish and they attempted to compensate by driving slower and increasing the following distance from the vehicle immediately in front of them. By contrast, when drivers were legally intoxicated they exhibited a more aggressive driving style, following closer to the vehicle immediately in front of them and applying more force while braking. When controlling for driving difficulty and time on task, cell-phone drivers exhibited greater impairment than intoxicated drivers
Behavioral Interventions for Climate Mitigation in Developing Countries : Overview and Prospects
Unidad de excelencia María de Maeztu CEX2019-000940-MBehavioral interventions are increasingly being considered as useful complements of traditional climate-policy instruments. These interventions are so far mostly being studied and applied in high-income countries. Here, we examine their application to achieve carbon emissions reduction in low- and middle-income countries. This involves synthesizing evidence from meta-analyses and systematic reviews from developed countries and deriving general insights for developing countries. We also review evidence from primary studies in developing countries, organizing insights by major world regions. We discuss context dependence of findings, as well to what extent behavioral interventions are complementary to, and create synergies with, other policy instruments. We hope that the present overview serves as starting point to expand the currently small evidence base on climate-relevant behavioral interventions in developing countries. Suggestions are made how to move this research forward
Identification of transcription-factor genes expressed in the Arabidopsis female gametophyte
Dongfang Wang, Changqing Zhang, David J. Hearn, Il-HO Kang, megan I. Skaggs, Karen S. Schumaker, and Ramin Yadegari are with the School of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036, USA -- Il-Ho Kang, Jayson A. Punwani, and Gary N. Drews are with the Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840, USA -- Changqing Zhang is with The Section of Molecular, Cell and Developmental Biology, University of Texas at Austin, Austin, Texas 78712-0159, USA -- David J. Hearn is with the Department of Biological Sciences, Towson University, Towson, Maryland 21252-0001, USA -- Il-Ho Kang is with the Department of Horticulture, Iowa State University, Ames, Iowa 50011-1100, USA --Jayson A. Punwani is with the Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3280, USABackground
In flowering plants, the female gametophyte is typically a seven-celled structure with four cell types: the egg cell, the central cell, the synergid cells, and the antipodal cells. These cells perform essential functions required for double fertilization and early seed development. Differentiation of these distinct cell types likely involves coordinated changes in gene expression regulated by transcription factors. Therefore, understanding female gametophyte cell differentiation and function will require dissection of the gene regulatory networks operating in each of the cell types. These efforts have been hampered because few transcription factor genes expressed in the female gametophyte have been identified. To identify such genes, we undertook a large-scale differential expression screen followed by promoter-fusion analysis to detect transcription-factor genes transcribed in the Arabidopsis female gametophyte.
Results
Using quantitative reverse-transcriptase PCR, we analyzed 1,482 Arabidopsis transcription-factor genes and identified 26 genes exhibiting reduced mRNA levels in determinate infertile 1 mutant ovaries, which lack female gametophytes, relative to ovaries containing female gametophytes. Spatial patterns of gene transcription within the mature female gametophyte were identified for 17 transcription-factor genes using promoter-fusion analysis. Of these, ten genes were predominantly expressed in a single cell type of the female gametophyte including the egg cell, central cell and the antipodal cells whereas the remaining seven genes were expressed in two or more cell types. After fertilization, 12 genes were transcriptionally active in the developing embryo and/or endosperm.
Conclusions
We have shown that our quantitative reverse-transcriptase PCR differential-expression screen is sufficiently sensitive to detect transcription-factor genes transcribed in the female gametophyte. Most of the genes identified in this study have not been reported previously as being expressed in the female gametophyte. Therefore, they might represent novel regulators and provide entry points for reverse genetic and molecular approaches to uncover the gene regulatory networks underlying female gametophyte development.Cellular and Molecular [email protected]
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