51 research outputs found

    Comparing Carbon Dioxide and Water Vapor Fluxes from Tilled and Non-tilled Maize Canopy Fields

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    Agricultural activities account for approximately 25% of worldwide greenhouse gas emissions. Farm management practices, such as tillage and no-tillage, may contribute more to this percentage than others. The two most abundant greenhouse gases responsible for climate change are CO2 and H2O, therefore it is important to determine whether tillage or no-tillage emits less of these gases. Fluxes of CO2 and H2O from two maize canopy fields, one with tillage and one with no-tillage, were measured in Indiana during the 2016 growing season. This study utilized the eddy covariance method, which represents flux as a covariance between vertical velocity and gas concentration. Measurements of canopy height and leaf area index (LAI) from both fields were collected since these parameters influence photosynthesis, respiration, and evapotranspiration rates and show differences in the growth of maize. Results showed that the tilled field had a 14% higher maximum CO2 uptake and a 4% higher maximum H2O flux to the atmosphere when LAI was 32% larger than the non-tilled field. Previous studies suggest these fluxes should be higher for the tilled field than what was measured. Drought conditions caused the maize to be water stressed, which restricted H2O loss and caused less CO2 uptake. These outcomes indicate that while maize canopies with tillage may typically have a higher CO2 uptake and higher H2O emissions than with no-tillage, this effect tends to disappear when maize is under water stress

    Transport infrastructure evaluation using cost-benefit analysis: improvements to valuing the asset through residual value—a case study

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    Residual value (RV) is an important component of Cost Benefit Analysis (CBA), often valued at 20% to 50% of total construction costs. It is often overlooked which can artificially depress the project?s returns. The treatment of RV is inadequate and needs further research. Residual value represents the value of the infrastructure at the end of its project lifetime and the value that the asset generates from then on. We analyze three methods for calculating RV: straight-line depreciation, annuity/perpetuity and component. The straight-line depreciation method is the most commonly used; it is simple and quick to produce and it typically uses a percent of the total construction cost rather than real value. The perpetuity/annuity method ignores the actual value of the asset. It reflects the difference of costs and benefits between economic and useful life (annuity method) or assumes an infinite economic life (perpetuity method). The component method is the most detailed and difficult to calculate method. It gives the actual value of the physical asset at the end of project appraisal by infrastructure component. We assume three scenarios for the future for the component method. We use the case study of the Portuguese High Speed Rail project to calculate and compare each method. As expected, the perpetuity has the highest RV and net present value (NPV), followed by the annuity method and then the component method. The straight-line method produces the lowest values (other than one scenario for the component method). Sensitivity analysis is performed ceteris paribus for the demand, construction cost and discount rate factors. We conclude that RV is important in situations when the benefit-cost ratio is close to 1 and the method selected can have a large impact on the size (and sign) of the NPV

    Considering the Definition of Addiction

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    The definition of addiction is explored. Elements of addiction derived from a literature search that uncovered 52 studies include: (a) engagement in the behavior to achieve appetitive effects, (b) preoccupation with the behavior, (c) temporary satiation, (d) loss of control, and (e) suffering negative consequences. Differences from compulsions are suggested. While there is some debate on what is intended by the elements of addictive behavior, we conclude that these five constituents provide a reasonable understanding of what is intended by the concept. Conceptual challenges for future research are mentioned

    Effects of a novel estrogen-free, progesterone receptor modulator contraceptive vaginal ring on inhibition of ovulation, bleeding patterns and endometrium in normal women

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    BACKGROUND: Progesterone receptor modulators (PRMs) delivered by contraceptive vaginal rings provide an opportunity for development of an estrogen-free contraceptive that does not require daily oral intake of steroids. The objective of this proof-of-concept study was to determine whether continuous delivery of 600–800 mcg of ulipristal acetate (UPA) from a contraceptive vaginal ring could achieve 80% to 90% inhibition of ovulation. STUDY DESIGN: This was a prospective, controlled, open-labeled, multicenter international trial to examine the effectiveness and safety of this prototype vaginal ring. Thirty-nine healthy women, 21–40 years old and not at risk of pregnancy, were enrolled at three clinic sites. Volunteers participated in a control cycle, a 12-week treatment period and a post-treatment cycle. Pharmacodynamic effects on follicular function and inhibition of ovulation, effects on endometrium, bleeding patterns and serum UPA levels were evaluated. RESULTS: Mean UPA levels during treatment were nearly constant, approximately 5.1 ng/mL throughout the study. Ovulation was documented in 32% of 111 “4-week treatment cycles.” A correlation was observed between serum UPA and degree of inhibition of ovarian activity. There was no evidence of hyperplasia of endometrium, but PRM-associated endometrial changes were frequently observed (41%). CONCLUSION: In this study, the minimum effective contraceptive dose was not established. Further studies are required testing higher doses of UPA to attain ovulation suppression in a higher percentage of subjects

    Progesterone vaginal ring: Introducing a contraceptive to meet the needs of breastfeeding women

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    Background: The 2012 London Summit on Family Planning called for innovative solutions for increasing contraceptive access for 120 million women and girls by 2020. One way of contributing to this goal is to address the contraceptive needs of postpartum women, who have considerable unmet need especially during lactation. The progesterone vaginal ring (PVR) has been shown to be effective and safe for breastfeeding women and has the potential to enhance contraceptive choice. This user-controlled method reduces dependence on health care providers and has the potential to reduce some access-related barriers that users face. Postpartum women who have used the method have found it easy to use and find it acceptable. A well-designed introductory approach is important to ensure that the PVR is integrated into health systems. Conclusion: The PVR is a new technology that increases contraceptive options for breastfeeding women and has the potential to improve the health of women and their infants. Careful planning with attention paid to numerous factors can result in its successful introduction

    Radical-Mediated Covalent Azidylation of Hydrophobic Microdomains in Water-Soluble Proteins

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    Hydrophobic microdomains, also known as hydrophobic patches, are essential for many important biological functions of water-soluble proteins. These include ligand or substrate binding, protein–protein interactions, proper folding after translation, and aggregation during denaturation. Unlike transmembrane domains, which are easily recognized from stretches of contiguous hydrophobic sidechains in amino acids via primary protein sequence, these three-dimensional hydrophobic patches cannot be easily predicted. The lack of experimental strategies for directly determining their locations hinders further understanding of their structure and function. Here, we posit that the small triatomic anion N3– (azide) is attracted to these patches and, in the presence of an oxidant, forms a radical that covalently modifies C–H bonds of nearby amino acids. Using two model proteins (BSA and lysozyme) and a cell-free lysate from the model higher plant Arabidopsis thaliana, we find that radical-mediated covalent azidylation occurs within buried catalytic active sites and ligand binding sites and exhibits similar behavior to established hydrophobic probes. The results herein suggest a model in which the azido radical is acting as an “affinity reagent” for nonaqueous three-dimensional protein microenvironments and is consistent with both the nonlocalized electron density of the azide moiety and the known high reactivity of azido radicals widely used in organic chemistry syntheses. We propose that the azido radical is a facile means of identifying hydrophobic microenvironments in soluble proteins and, in addition, provides a simple new method for attaching chemical handles to proteins without the need for genetic manipulation or specialized reagents

    Radical-Mediated Covalent Azidylation of Hydrophobic Microdomains in Water-Soluble Proteins

    No full text
    Hydrophobic microdomains, also known as hydrophobic patches, are essential for many important biological functions of water-soluble proteins. These include ligand or substrate binding, protein–protein interactions, proper folding after translation, and aggregation during denaturation. Unlike transmembrane domains, which are easily recognized from stretches of contiguous hydrophobic sidechains in amino acids via primary protein sequence, these three-dimensional hydrophobic patches cannot be easily predicted. The lack of experimental strategies for directly determining their locations hinders further understanding of their structure and function. Here, we posit that the small triatomic anion N3– (azide) is attracted to these patches and, in the presence of an oxidant, forms a radical that covalently modifies C–H bonds of nearby amino acids. Using two model proteins (BSA and lysozyme) and a cell-free lysate from the model higher plant Arabidopsis thaliana, we find that radical-mediated covalent azidylation occurs within buried catalytic active sites and ligand binding sites and exhibits similar behavior to established hydrophobic probes. The results herein suggest a model in which the azido radical is acting as an “affinity reagent” for nonaqueous three-dimensional protein microenvironments and is consistent with both the nonlocalized electron density of the azide moiety and the known high reactivity of azido radicals widely used in organic chemistry syntheses. We propose that the azido radical is a facile means of identifying hydrophobic microenvironments in soluble proteins and, in addition, provides a simple new method for attaching chemical handles to proteins without the need for genetic manipulation or specialized reagents
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