15,384 research outputs found
Gaseous emissions from plants in controlled environments
Plant growth in a controlled ecological life support system may entail the build-up over extended time periods of phytotoxic concentrations of volatile organic compounds produced by the plants themselves. Ethylene is a prominent gaseous emission of plants, and is the focus of this report. The objective was to determine the rate of ethylene release by spring wheat, white potato, and lettuce during early, middle, and late growth stages, and during both the light and dark segments of the diurnal cycle. Plants grown hydroponically using the nutrient film technique were covered with plexiglass containers for 4 to 6 h. At intervals after enclosure, gas samples were withdrawn with a syringe and analyzed for ethylene with a gas chromatograph. Lettuce produced 10 to 100 times more ethylene than wheat or potato, with production rates ranging from 141 to 158 ng g-dry/wt/h. Wheat produced from 1.7 to 14.3 ng g-dry/wt/h, with senescent wheat producing the least amount and flowering wheat the most. Potatoes produced the least amount of ethylene, with values never exceeding 5 ng g-dry/wt/h. Lettuce and potatoes each produced ethylene at similar rates whether in dark period or light period. Ethylene sequestering of 33 to 43 percent by the plexiglass enclosures indicated that these production estimates may be low by one-third to one-half. These results suggest that concern for ethylene build-up in a contained atmosphere should be greatest when growing lettuce, and less when growing wheat or potato
Do Convolutional Networks need to be Deep for Text Classification ?
We study in this work the importance of depth in convolutional models for
text classification, either when character or word inputs are considered. We
show on 5 standard text classification and sentiment analysis tasks that deep
models indeed give better performances than shallow networks when the text
input is represented as a sequence of characters. However, a simple
shallow-and-wide network outperforms deep models such as DenseNet with word
inputs. Our shallow word model further establishes new state-of-the-art
performances on two datasets: Yelp Binary (95.9\%) and Yelp Full (64.9\%)
The Evolution of the Visible and Hidden Star Formation in the Universe: Implication from the Luminosity Functions at FUV and FIR
Based on GALEX and IRAS/Spitzer datasets, we have found that both FUV and FIR
luminosity functions (LFs) show a strong evolution from z=0 to z=1, but the FIR
LF evolves much stronger than the FUV one. Consequently, the FIR/FUV luminosity
density ratio increases from 4 (z=0) to 15 (z=1). It means that more than 80%
of the star-forming activity in the Universe is hidden by dust at z=1. To
explore this issue further, we have performed a combined analysis of the galaxy
sample in FUV and FIR. For the Local Universe we used GALEX-IRAS sample,
whereas at z=1 we used the Lyman-break galaxy sample selected by GALEX bands
constructed by Burgarella et al. (2005), which is known to be representative of
visible (i.e., non-obscured) star-forming galaxies at z=1. From these datasets,
we constructed the LFs of the FUV-selected galaxies by the survival analysis
to, take into account the upper-limit data properly. We discovered that the FIR
LF of the Lyman-break galaxies show a significant evolution comparing with the
local FIR LF, but it is a factor of 2-3 lower than the global FIR LF (Le Floc'h
et al. 2005). This indicates that the evolution of visible galaxies is not
strong enough to explain the drastic evolution of the FIR LF. Namely, a
FIR-luminous, rapidly diminishing population of galaxies is required.Comment: 4 pages, 4 figures, conference proceedings of "At the Edge of the
Universe", Sintra 9-13 October 200
Household Composition, Living Standards, and “Needs”. ESRI Working Paper No. 106, 1999
This study uses the 1987 ESRI Survey of Income Distribution, Poverty and
Use of State Services and the 1994 Living in Ireland Survey to examine two issues of
immediate relevance to Irish tax and social welfare policy. The first is how the living
standards of different household types have been evolving in recent years. The second
is the relationship between the “needs” of one household type versus another - for
example a single adult versus a couple, or a couple with no children versus a couple
with four children. Both issues are critical for the Inter-Departmental Working Group
set up in 1998 to examine the treatment of married, cohabiting and one-parent
households under the tax and social welfare codes. This study was undertaken in the
first instance as a contribution to the work of that group, and is being published in
order to inform the wider debate of these issues. In this introductory chapter we
outline the issues to be addressed, and then look at how household composition has
been changing over the period to provide the background for the remainder of the
study
The wall shear stress produced by the normal impingement of a jet on a flat surface
A method for the theoretical determination of the wall shear stress under impinging jets of various congurations is presented. Axisymmetric and two-dimensional
incompressible jets of a wide range of Reynolds numbers and jet heights are considered. Theoretical predictions from this approach are compared with available wall shear stress measurements. These data are critically evaluated based on the method of measurement and its applicability to the boundary layer under consideration. It was found that impingement-region wall shear stress measurements using the electrochemical method in submerged impinging liquid jets provide the greatest accuracy of any indirect method. A unique wall shear stress measurement technique, based
on observing the removal of monosized spheres from well-characterized surfaces, was used to conrm the impinging jet analysis presented for gas jets. The technique was also used to determine an empirical relation describing the rise in wall shear stress due to compressibility eects in impinging high-velocity jets
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