950 research outputs found
Citation Flows in the Zones of Influence of Scientific
Domestic citation to papers from the same country and the greater citation impact of documents involving international collaboration are two phenomena that have been extensively studied and contrasted. Here, however, we showthat it is not somuch a national bias,but that papers have a greater impact on their immediate environments, an impact that is diluted as that environment grows. For this reason, the greatest biases are observed in countries
with a limited production. Papers that involve international collaboration have a greater impact in general, on the one hand, because they have multiple âimmediate
environments,â and on the other because of their greater quality or prestige. In short, one can say that science knows no frontiers. Certainly there is a greater impact
on the authorsâ immediate environment, but this does not necessarily have to coincide with their national environments, which fade in importance as the collaborative
environment expands
Growth and physiological responses of lettuce grown under pre-dawn or end-of-day sole-source light-quality treatments
The objective of this study was to evaluate growth and physiological responses of âCherokeeâ and âWaldmannâs Greenâ lettuce (Lactuca sativa) exposed to small changes in light quality and intensity within a 24-h period. Three pre-dawn (PD; 0600 to 0700) and three end-of-day (EOD; 2100 to 2200) treatments were evaluated in the study, each providing 50 ± 2 ÎŒmol·mâ2·sâ1 of either blue, red, or broadband white light from light-emitting diodes (LEDs). To account for the main daily light integral (DLI), broadband white LEDs provided 210 ± 2 ÎŒmol·mâ2·sâ1 from 0700 to 2200 or from 0600 to 2100 for the PD or EOD treatments, respectively. A control treatment was included which provided 200 ± 2 ÎŒmol·mâ2·sâ1 of white light from 0600 to 2200. All treatments provided a DLI of 11.5 mol·mâ2·dayâ1 over a 16-h photoperiod. Regardless of cultivar, no treatment difference was measured for hypocotyl length or leaf number. However, plants grown under EOD-blue or PD-white had up to 26% larger leaves than those grown under PD-red and 20% larger leaves than control. In addition, plants grown under EOD-blue produced up to 18% more shoot fresh mass compared to those grown under control, EOD-red, or PD-red. Contrasts for gas-exchange data collected during the main photoperiod showed that light quality was not significant within PD or EOD for any of the parameters evaluated. However, regardless of light quality, stomatal conductance (gs) and transpiration (E) were up to 34% and 42% higher, respectively, for EOD-grown plants compared to control. Our results suggest that 1 h of low intensity EOD-blue light has the potential to promote lettuce growth by increasing leaf area and shoot fresh mass when the main DLI from sole-source lighting is provided by broadband white LEDs
AnĂĄlisis estructural del Bosque Muy HĂșmedo Tropical en la zona norte de Costa Rica: un estudio de caso
No disponible/Not availabl
Whistler Waves Driven by Anisotropic Strahl Velocity Distributions: Cluster Observations
Observed properties of the strahl using high resolution 3D electron velocity distribution data obtained from the Cluster/PEACE experiment are used to investigate its linear stability. An automated method to isolate the strahl is used to allow its moments to be computed independent of the solar wind core+halo. Results show that the strahl can have a high temperature anisotropy (T(perpindicular)/T(parallell) approximately > 2). This anisotropy is shown to be an important free energy source for the excitation of high frequency whistler waves. The analysis suggests that the resultant whistler waves are strong enough to regulate the electron velocity distributions in the solar wind through pitch-angle scatterin
Ensayos de aclareo en plantaciones de Tectona grandis L.F. en CĂłbano de Puntarenas, Costa Rica
No disponible/Not availabl
Tratamientos silviculturales en el manejo de los bosques naturales tropicales
No disponible/Not availabl
Citation Flows in the Zones of Influence of Scientific
Domestic citation to papers from the same country and the greater citation impact of documents involving international collaboration are two phenomena that have been extensively studied and contrasted. Here, however, we showthat it is not somuch a national bias,but that papers have a greater impact on their immediate environments, an impact that is diluted as that environment grows. For this reason, the greatest biases are observed in countries
with a limited production. Papers that involve international collaboration have a greater impact in general, on the one hand, because they have multiple âimmediate
environments,â and on the other because of their greater quality or prestige. In short, one can say that science knows no frontiers. Certainly there is a greater impact
on the authorsâ immediate environment, but this does not necessarily have to coincide with their national environments, which fade in importance as the collaborative
environment expands
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