566 research outputs found
The dynamics of embolism refilling in abscisic acid (ABA)-deficient tomato plants.
Plants are in danger of embolism formation in xylem vessels when the balance between water transport capacity and transpirational demand is compromised. To maintain this delicate balance, plants must regulate the rate of transpiration and, if necessary, restore water transport in embolized vessels. Abscisic acid (ABA) is the dominant long-distance signal responsible for plant response to stress, and it is possible that it plays a role in the embolism/refilling cycle. To test this idea, a temporal analysis of embolism and refilling dynamics, transpiration rate and starch content was performed on ABA-deficient mutant tomato plants. ABA-deficient mutants were more vulnerable to embolism formation than wild-type plants, and application of exogenous ABA had no effect on vulnerability. However, mutant plants treated with exogenous ABA had lower stomatal conductance and reduced starch content in the xylem parenchyma cells. The lower starch content could have an indirect effect on the plant's refilling activity. The results confirm that plants with high starch content (moderately stressed mutant plants) were more likely to recover from loss of water transport capacity than plants with low starch content (mutant plants with application of exogenous ABA) or plants experiencing severe water stress. This study demonstrates that ABA most likely does not play any direct role in embolism refilling, but through the modulation of carbohydrate content, it could influence the plant's capacity for refilling
Privatizing Ecosystem Services: Water Quality Effects from a Carbon Market
Resource /Energy Economics and Policy, Q25,
Structure and pattern of food consumption in Italian household: an analysis of impact on climate change and land use
The environmental impacts of food consumption of Italian households in 2011 have been
calculated adopting an Environmentally Extended Input-Output Analysis, using EXIOBASE v3 as
the underpinning database for the assessment. Because of the structure of such database, it is
possible to divide domestic and imported final demand. Climate change and Land use related
impacts are calculated then matched with household expenditures for the same year. The food
consumption in an average Italian household for 2011 results in a total Climate change of 4237
kg CO2eq and in a total Land use impact of 10 kg Cdeficit. There are limitations due to a non-perfect
match of food product groups in EXIOBASE and Italian National Statistics. Nevertheless, with this
approach it is possible to investigate environmental impacts in relation to expenditure patterns of
the families
New, efficient, and accurate high order derivative and dissipation operators satisfying summation by parts, and applications in three-dimensional multi-block evolutions
We construct new, efficient, and accurate high-order finite differencing
operators which satisfy summation by parts. Since these operators are not
uniquely defined, we consider several optimization criteria: minimizing the
bandwidth, the truncation error on the boundary points, the spectral radius, or
a combination of these. We examine in detail a set of operators that are up to
tenth order accurate in the interior, and we surprisingly find that a
combination of these optimizations can improve the operators' spectral radius
and accuracy by orders of magnitude in certain cases. We also construct
high-order dissipation operators that are compatible with these new finite
difference operators and which are semi-definite with respect to the
appropriate summation by parts scalar product. We test the stability and
accuracy of these new difference and dissipation operators by evolving a
three-dimensional scalar wave equation on a spherical domain consisting of
seven blocks, each discretized with a structured grid, and connected through
penalty boundary conditions.Comment: 16 pages, 9 figures. The files with the coefficients for the
derivative and dissipation operators can be accessed by downloading the
source code for the document. The files are located in the "coeffs"
subdirector
ResĂduo do processo de fabricação de papel reciclado - potencial de uso como insumo agrĂcola e/ou florestal.
Resumo
Revision of Solar Spicule Classification
Solar spicules are the fundamental magnetic structures in the chromosphere
and considered to play a key role in channelling the chromosphere and corona.
Recently, it was suggested by De Pontieu et al. that there were two types of
spicules with very different dynamic properties, which were detected by space-
time plot technique in the Ca ii H line (3968 A) wavelength from Hinode/SOT
observations. 'Type I' spicule, with a 3-7 minute lifetime, undergoes a cycle
of upward and downward motion; in contrast, 'Type II' spicule fades away within
dozens of seconds, without descending phase. We are motivated by the fact that
for a spicule with complicated 3D motion, the space-time plot, which is made
through a slit on a fixed position, could not match the spicule behavior all
the time and might lose its real life story. By revisiting the same data sets,
we identify and trace 105 and 102 spicules in quiet sun (QS) and coronal hole
(CH), respectively, and obtain their statistical dynamic properties. First, we
have not found a single convincing example of 'Type II' spicules. Secondly,
more than 60% of the identified spicules in each region show a complete cycle,
i.e., majority spicules are 'Type I'. Thirdly, the lifetime of spicules in QS
and CH are 148 s and 112 s, respectively, but there is no fundamental lifetime
difference between the spicules in QS and CH reported earlier. Therefore, the
suggestion of coronal heating by 'Type II' spicules should be taken with
cautions. Subject headings: Sun: chromosphere Sun:transition region Sun:coronaComment: accepted by Ap
Awareness, Co-operation, Tackling to Stop Sexual Bullying: An empowerment pack for young people and the people working with them (The ACT Pack).
Available in English, Bulgarian, Slovenian and Italia
Improving substance information in usetox®, part 1: discussion on data and approaches for estimating freshwater ecotoxicity effect factors
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