380 research outputs found
Wheat response to CO2 enrichment: CO2 exchanges transpiration and mineral uptakes
When simulating canopies planted in varied densities, researchers were able to demonstrate that increase of dry matter production by enhancing CO2 quickly becomes independant of increase of leaf area, especially above leaf area index of 2; dry matter gain results mainly from photosynthesis stimulation per unit of surface (primary CO2 effect). When crop density is low (the plants remaining alone a longer time), the effects of increasing leaf surface (tillering, leaf elongation here, branching for other plants etc.) was noticeable and dry matter simulation factor reached 1.65. This area effect decreased when canopy was closed in, as the effect of different surfaces no longer worked. The stimulation of photosynthesis reached to the primary CO2 effect. The accumulation in dry matter which was fast during that phase made the original weight advantage more and more neglectible. Comparison with short term measurements showed that first order long term effect of CO2 in wheat is predictible with short term experiment, from the effect of CO2 on photosynthesis measured on reference sample
Divergent series and differential equations
We develop the various known approaches to the summability of a class of series that contains all divergent series solutions of ordinary differential equations in the complex field. We first study the case when the divergence depends only on one parameter (the level k or critical time) called k-summability. We study then generalizations to the case when the divergence depends on several levels called multi-summability. We prove the coherence of the definitions and their equivalences and we provide some applications. We also provide the necessary basics on Gevrey asymptotics and a survey of sheaf theory, cohomology and linear ordinary differential equations. Various examples are worked on, including the example of tangent-to-identity germs of diffeomorphisms in the complex plane
Can plants grow in quasi-vacuum?
It was found that the growth of plants is possible under absolute pressure 14 times lower than the atmospheric pressure. In first approximation, plants ignore the absence of nitrogen and only react to the partial pressure of O2. Hence the growth of plantlets was delayed under low pressures of O2 in both cases with and without nitrogen. The CO2 availability being limited by the carbon content of the seed, the final results after 20 days were very similar
The Transformation of Sediment Into Rock : Insights From IODP Site U1352, Canterbury Basin, New Zealand
ACKNOWLEDGMENTS We thank the crew of the RV JOIDES Resolution for professional seamanship, excellent drilling, and the scientific support on board. GHB and SCG thank the Australia–New Zealand IODP Consortium (ANZIC), and KMM thanks the Consortium for Ocean Leadership U.S. Science Support Program for partly funding this work. Thanks also to funding agencies of the respective authors, and Mark Lawrence (GNS Science) and Cam Nelson (University of Waikato) for their thoughtful comments on an earlier draft. Karsten Kroeger (GNS Science) helped by providing compaction data for New Zealand basins, and Michelle Kominz (Western Michigan University) provided data on which Figure 8 was developed. Further improvements were the result of thoughtful detailed reviews by Gemma Barrie, Bill Heins, Stan Paxton, Associate Editor Joe Macquaker, and Editor Leslie Melim.Peer reviewedPostprin
Interaction-enhanced flow of a polariton superfluid current in a ring
We study the quantum hydrodynamical features of exciton polaritons flowing circularly in a ring-shaped geometry. We consider a resonant-excitation scheme in which the spinor polariton fluid is set into motion in both components by spin-to-orbital angular momentum conversion. We show that this scheme allows us to control the winding number of the fluid and to create two circulating states differing by two units of the angular momentum. We then consider the effect of a disorder potential, which is always present in realistic nanostructures. We discuss how a smooth disorder can be efficiently screened by the polariton-polariton interactions, yielding a signature of polariton superfluidity. This effect is reminiscent of supercurrent in a superconducting loo
Parental Expectations and Prosocial Behavior of Adolescents From Low-Income Backgrounds: A Cross-Cultural Comparison Between Three Countries¿Argentina, Colombia, and Spain
Parental expectations are influenced by cultural models, which in turn are subject to a great influence from historically fluctuating features of the socioeconomic background. Parental expectations seem to be linked to children¿s social and emotional development in terms of empathy and prosocial behavior. The current study aims to (a) compare low-income adolescents¿ perceptions of parental expectations of prosocial and antisocial behavior across three Latin countries (Argentina, Colombia, and Spain), (b) compare the empathy and prosocial behavior between the three countries, (c) compare the prosocial behavior between the three countries, and (d) study the effect of perceived parental expectations and empathy on the prosocial behavior of adolescents in all three of the countries studied in this research. The sample was made up of 446 Argentinean adolescents, 474 Colombian adolescents, and 632 Spanish adolescents. The Expected Parental Reactions Scale, Interpersonal Reactivity Index, and Prosocial Behavior Questionnaire were used to measure the variables included in this study. Results reveal considerable differences between children¿s perceptions of parental expectations in different countries. Results also show the existence of significant differences between male and female adolescents. In all three countries, girls score more highly than boys in prosocial behavior and empathy. Furthermore, we find that low-income Argentinean adolescents score more highly than Spanish and Colombian adolescents in prosocial behavior measures. Finally, expected parental reactions toward prosocial behavior and empathy seem to have an influence on the adolescents¿ development of prosocial behavior in all three countries
Surface and bottom temperature and salinity climatology along the continental shelf off the Canadian and U.S. East Coasts
© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Continental Shelf Research 124 (2016): 165-181, doi:10.1016/j.csr.2016.06.005.A new hydrographic climatology has been created for the continental shelf region, extending from the Labrador shelf to the Mid-Atlantic Bight. The 0.2-degree climatology combines all available observations of surface and bottom temperature and salinity collected between 1950 and 2010 along with the location, depth and date of these measurements. While climatological studies of surface and bottom temperature and salinity have been presented previously for various regions along the Canadian and U.S. shelves, studies also suggest that all these regions are part of one coherent system. This study focuses on the coherent structure of the mean seasonal cycle of surface and bottom temperature and salinity and its variation along the shelf and upper slope. The seasonal cycle of surface temperature is mainly driven by the surface heat flux and exhibits strong dependency on latitude (r≈−0.9). The amplitude of the seasonal cycle of bottom temperature is rather dependent on the depth, while the spatial distribution of bottom temperature is correlated with latitude. The seasonal cycle of surface salinity is influenced by several components, such as sea-ice on the northern shelves and river discharge in the Gulf of St. Lawrence. The bottom salinity exhibits no clear seasonal cycle, but its spatial distribution is highly correlated with bathymetry, thus Slope Water and its intrusion on the shelf can be identified by its relatively high salinity compared to shallow, fresher shelf water. Two different regimes can be identified, especially on the shelf, separated by the Laurentian Channel: advection influences the phasing of the seasonal cycle of surface salinity and bottom temperature to the north, while in the southern region, river runoff and air-sea heat flux forcing are dominant, especially over the shallower bathymetry.Support from NSF OCE PO to Y-OK (OCE-1242989 and OCE-1435602) and SJL (OCE-1332666)
Study of the relationship between photosynthesis, respiration, transpiration, and mineral nutrition in wheat
The growth of wheat (triticum aestivum) was studied in an enclosed controlled environment for a period of 70 days. The exchange of gases (photosynthesis, respiration), water (transpiration) and the consumption of mineral elements (nitrogen, phosphorus, potassium) were continuously measured. The dynamical relations observed in the different physiological functions, under the influence of growth and in response to environment modifications are presented. The influence of carbon dioxide content during growth (normal or double percentage) was made clear
XXVII International Congress of Psychology, Estocolmo, 2000 : Simposio "Science from the standpoint of cognitive psychology"
Contiene los resúmenes de:
Science rationality and inference : an insight from cognitive psychology / Prof. Dr. Alfredo Oscar López Alonso ; Cognitive maps across cultures and across sciences / Dr. Horacio J. A. Rimoldi ; Subjective and objective causality in science : a topic for attribution theory? / Prof. Dra. María Cristina Richaud de Minzi ; Metacognition and learning processes underlying science / Drnd. Pablo Narvaja & M. A. Carolina Jaroslavsk
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