31,685 research outputs found
Root developmental responses to heterogeneous water and nitrogen supply
Full text linkBetter understanding of the interaction between the soil physical properties determining water and nitrate availability and the root proliferation and gene expression components of nutrient acquisition could contribute to food security, but may have been limited by experimental systems.
A sand rhizotron system was developed to investigate Arabidopsis (Arabidopsis thaliana) root responses to altered water and nitrate supply as manipulated by soil physical properties. When this system was compared to agar, root disparities were explained by differences in hydraulic properties, highlighting the importance of the soil physical component. The sand rhizotron system was adopted to quantify root proliferation and gene expression responses to altered water and nitrate availability in wild-type and selected mutant seedlings.
In the sand rhizotron system, primary root length and lateral root density were oppositely regulated by water availability, but similarly independent of nitrate supply. The expression of the nitrate transporter AtNRT2.1 and the aquaporin AtPIP2.2 was coordinated across all treatments. Their concentration-dependent hydraulic regulation was confirmed for AtNRT2.1 by in situ imaging of a Green Fluorescent Protein reporter line. AtNAR2.1 and AtNRT2.1 expression demonstrated independent responses to water and nitrate availability despite the requirement of AtNAR2.1 for AtNRT2.1 uptake function. Root proliferation responses to water availability under high (10.0 mM) nitrate were lost in the atnar2.1 mutant and coincided with altered hormone-associated gene (AtEIN2, AtABI4 and AtIPT5) expression. Root proliferation and AtNAR2.1 responses to water availability under high (10.0 mM) nitrate required AtPIP2.2. The coordination of root proliferation and gene expression responses to altered water and nitrate availability is proposed, that includes novel roles for AtNRT2.1, AtNAR2.1 and AtPIP2.2
Conflictos y resistencias en torno a la identidad mapuche en el sistema escolar de Chubut. Un estudio de caso en la Escuela Provincial Nº 22 de El Maitén
No full textFil: Root, Daniel. Universidad Pedagógica Nacional
Conflictos y resistencias en torno a la identidad mapuche en el sistema escolar de Chubut. Un estudio de caso en la Escuela Provincial Nº 22 de El Maitén
No full textFil: Root, Daniel. Universidad Pedagógica Nacional
Conflictos y resistencias en torno a la identidad mapuche en el sistema escolar de Chubut. Un estudio de caso en la Escuela Provincial Nº 22 de El Maitén
No full textFil: Root, Daniel. Universidad Pedagógica Nacional
Report on Meteorological Research March 1, 1935 (m-1)
No full textThe object of the report was to elucidate in detail the various features of the research program in meteorology being carried on at the Daniel Guggenheim Airship Institute in Akron, Ohio. Mr. L. J. Fangman, of the U.S. Weather Bureau, was collaborating with the author in carrying out work such as a study of autographic records of the various meteorological elements during frontal passages with a view to the possible prediction of the intensity of the accompanying disturbance as it may affect the operation of aircraft and a study of atmospheric gustiness with a view to finding the dependence between frequency end amplitude of velocity fluctuations and the vertical temperature and velocity gradients
Measurement of the Forces and Moments caused by an Artificial Gust on Different Types of Control Surfaces on the 1/150 Akron Model, Report on Item 4, contract NOS-78742
No full textThis report on the direct measurement in the water tank of the normal forces and moments caused by an artificial gust on four different types of control surfaces installed on the 1/150 AKRON model was carried out at the Daniel Guggenheim Airship Institute in Akron, Ohio. The purpose of the tests was to determine by direct measurement in the water gust channel the normal forces, pitching moments and root moments on four different types of control surfaces installed on the 1/150 AKRON model as the model passed through an artificial gust of known intensity
(Fourth) Report on Meteorological Activities at the DGAI (8-1-36)(Weather Bureau Copy)
No full textThis report is on the investigations of frontal phenomena at the Daniel Guggenheim Airship Institute in Akron, Ohio from January 1, 1935 through August 1, 1936. The investigation was carried out with the cooperation of the U.S. Bureau of Aeronautics, the U.S. Weather Bureau, the California Institute of Technology, and the Guggenheim Airship Institute. Mr. R.C. Robinson of the Weather Bureau cooperated with the author in carrying out the investigation. The object of the investigation was to determine the intensity of the atmospheric disturbances (i.e. rapidity of wind shift and gustiness) accompanying the passage of cold fronts, along with a study of the characteristics of the air masses involved and other features which might affect the intensity of the disturbance. The report treated thirty cold fronts which passed the station during 1935 to 1936
Archives and Images as Repositories of Time, Language, and Forms from the Past: A Conversation with Daniel Eisenberg
Full text linkJournal of My Life by Jacques-Louis Ménétra, présenté par Daniel Roche, traduit en anglais par Arthur Goldhammer
No full textRoot-Bernstein Michèle. Journal of My Life by Jacques-Louis Ménétra, présenté par Daniel Roche, traduit en anglais par Arthur Goldhammer. In: Revue d’histoire moderne et contemporaine, tome 36 N°1, Janvier-mars 1989. pp. 174-178
A range unit root test
Full text linkSince the seminal paper by Dickey and Fuller in 1979, unit-root tests have conditioned the standard approaches to analyse time series with strong serial dependence, the focus being placed in the detection of eventual unit roots in an autorregresive model fitted to the series. In this paper we propose a completely different method to test for the type of long-wave patterns observed not only in unit root time series but also in series following more complex data generating mechanisms. To this end, our testing device analyses the trend exhibit by the data, without imposing any constraint on the generating mechanism. We call our device the Range Unit Root (RUR) Test since it is constructed from running ranges of the series. These statistics allow a more general characterization of a strong serial dependence in the mean behavior, thus endowing our test with a number of desirable properties, among which its error-model-free asymptotic distribution, the invariance to nonlinear monotonic transformations of the series and the robustness to the presence of level shifts and additive outliers. In addition, the RUR test outperforms the power of standard unit root tests on near-unit-root stationary time series and is asymptotically immune to noise
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