scholarly journals Availability of anions in the growth medium to roots of an actively growing plant.

1975 ◽  
Vol 23 (2) ◽  
pp. 131-138
Author(s):  
H. Van Keulen ◽  
N.G. Seligman ◽  
J. Goudriaan
Keyword(s):  
Root System ◽  
Growth Medium ◽  
Mass Flow ◽  
Dispersion Coefficient ◽  
Anion Transport ◽  
Root Density ◽  
High Dispersion ◽  
Rooting Zone ◽  
Speed Up ◽  
Low Dispersion

Analysis of anion transport to the root of an actively growing plant with a normally dense root system showed that virtually the whole of the anion store in the rooting zone is available to the plant within a few days at the most. Transport by diffusion only is enough to account for most of the depletion, but mass flow will speed up the process. The effect of mass flow will be considerable in soils with a high dispersion coefficient (loess), but very small in soils with a low dispersion coefficient (clay and sand). A rule is proposed to determine whether a given root density is sufficient to supply the nitrogen and water needs of the plant by diffusion only. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Electronic spectra of polyatomic molecules II–Acrolein

1935 ◽  
Vol 149 (868) ◽  
pp. 446-466 ◽  
Keyword(s):  
Excited States ◽  
Theoretical Description ◽  
High Dispersion ◽  
Molecular Spectra ◽  
Orbital Structure ◽  
Double Bonds ◽  
Important Place ◽  
Conjugated Systems ◽  
The Difference ◽  
Low Dispersion

In the Introduction to Part I we discussed the orbital structure of the C > C and >C = O double bonds and the difference between these structures in their excited states. With so much spectroscopic evidence upon these isolated double bonds, and at least a provisional theoretical description of each of them, it seemed natural to investigate the effect of double bonds upon each other in conjugated systems such as > C = C - C = 0. These systems occupy an important place in chemical theories of valency. Another reason for investigating such molecules was that measurements under low dispersion by Luthy upon the simplest conjugated aldehyde CH 2 = CH. C = O | H showed a spectrum which gave promise of unusual features. This promise was more than borne out by observations under high dispersion, and in fact the spectrum of acrolein reveals a tine structure which so far as we know is unique in molecular spectra at present recorded.

scholarly journals On the Simple Economics of Advertising, Marketing, and Product Design

2006 ◽  
Vol 96 (3) ◽  
pp. 756-784 ◽  
Author(s):  
Justin P Johnson ◽  
David P Myatt
Keyword(s):  
Product Design ◽  
Demand Curve ◽  
High Dispersion ◽  
Product Lines ◽  
Mass Market ◽  
Low Dispersion

We propose a framework for analyzing transformations of demand. Such transformations frequently stem from changes in the dispersion of consumers' valuations, which lead to rotations of the demand curve. In many settings, profits are a U-shaped function of dispersion. High dispersion is complemented by niche production, and low dispersion is complemented by mass-market supply. We investigate numerous applications, including product design; advertising, marketing and sales advice; and the construction of quality-differentiated product lines. We also suggest a new taxonomy of advertising, distinguishing between hype, which shifts demand, and real information, which rotates demand.

Root distribution as function of litter layer management in eucalypt stands

2020 ◽  
Author(s):  
Ana Paula Mendes Teixeira ◽  
Pedro Paulo de C. Teixeira ◽  
Luís Fernando J. Almeida ◽  
Letícia C. F. Silva ◽  
Danilo H. S. Silva ◽  
...  
Keyword(s):  
Root System ◽  
Nutrient Availability ◽  
Soil Profile ◽  
Nutrient Use Efficiency ◽  
Root Density ◽  
Sampling Point ◽  
Litter Layer ◽  
Soil Layers ◽  
Fast Growing ◽  
Macro And Micronutrients

<p>The distribution of root system in the soil profile is an important factor for water and nutrient acquisition in planted forests. Harvest residue and litter layer management can alter nutrient availability to the plants, reflecting in shifts of root system distribution in the soil profile. In the present study, we aimed to evaluate the effect of litter layer management in root density and its correlation with depth, soil organic matter (SOM), and soil macro and micronutrients in fast-growing eucalypt plantations. We hypothesized that the presence of litter layer increases root density in the first soil layers while its absence results in higher root density in deeper soil layers. To this end we carried out an experiment in a eucalypt stand (<em>Eucalyptus urophylla</em> x <em>Eucalyptus grandis</em>; 3.3 x 1.82 m spacing; one-year-old trees) in the region of Telêmaco Borba, Paraná – Brazil. The Köppen climate classification is Cfb and the soil is classified as dystrophic Red Latosol. The treatments consisted of presence (+R) or absence (-R) of litter layer. The residue was composed by the previous rotation litter layer that remained in the forest after harvest. The experiment followed a randomized block design, with four replications. Root density (g dm<sup>-3</sup>) was evaluated in one representative tree per plot at each treatment and replication. We used a 5.3 cm diameter auger to collect root samples from 0-10, 10-20, 20-40 and 40-60 cm depths in seven predefined points in the planting row and interrow. For each sampling point and depth, roots were manually separated, washed to remove soil and other impurities, and subsequently oven dried at 65 °C to determine total dry mass. Additionally, SOM, soil macro and micronutrient contents were analyzed in each soil layer. Pearson’s correlation (α=5%) was performed between root density, depth, SOM, soil macro and micronutrients. Contrary to our hypothesis, the results showed that the presence of litter layer did not impacted root density in the superficial layer (0-20 cm), but resulted in a substantial increase of this trait in deeper soil layers (20-40 cm and 40-60 cm). The increase in root density observed for deeper soil layers was possibly a consequence of the higher nutrient availability favored by the presence of litter layer. The increase of root density in subsurface is important not only to increase tree water and nutrient use efficiency, but also to promote C sequestration in deeper soil layers. Our results highlight the importance of maintaining the litter layer in the field as reasonable strategy for a more sustainable management of fast-growing eucalypt forests.</p>

scholarly journals Spacial distribution of fertigated coffee root system

2017 ◽  
Vol 41 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Marcelo Rossi Vicente ◽  
Everardo Chartuni Mantovani ◽  
André Luís Teixeira Fernandes ◽  
Júlio César Lima Neves ◽  
Edmilson Marques Figueredo ◽  
...  
Keyword(s):  
Root System ◽  
Drip Irrigation ◽  
Root Length ◽  
Root Length Density ◽  
Plant Root ◽  
Root Density ◽  
Coffee Plant ◽  
Coffee Plants ◽  
Plant Root System ◽  
Different Levels

ABSTRACT The development of coffee plant root system changes when subjected to drip irrigation and fertigation. This work aimed to evaluate the effects of different levels of fertigation on the development of coffee root system by drip irrigation in western Bahia. The experiment was carried out with Catuaí Vermelho IAC 144 coffee plants, of about 3.5 years of age, in the “Café do Rio Branco” farm, located in Barreiras - BA, and consisted of a complete randomized blocks design with 3 replicates. Treatments consisted of three levels of nitrogen and potassium fertilization (900/800, 600/500 and 300/250 kg ha-1 year-1 N and K2O), weekly distributed, by means of fertigation, throughout the process. After the fourth harvest, coffee root system was evaluated, and root length density (RLD) and root density (RD) were determined at different sampled layers. The highest root concentration, root length density (RLD), and root density (RD) were observed in the superficial layers of soil (0-20 cm), and under the dripline (30 and 70 cm from the orthotropic branch). Results showed that the lower the N and K2O levels, the higher was the development (RLD and RD) of the coffee root system.

Emission Inhomogeneity in InAs Quantum Dot DWELL Structures

2010 ◽  
Vol 1257 ◽  
Author(s):  
Alejandro Vivas Hernández ◽  
Gerorgiy Polupan ◽  
Eric Velazquez ◽  
Ingri J. Guerrero Moreno ◽  
L. Scherbyna
Keyword(s):  
Excitation Power ◽  
High Dispersion ◽  
Excitation Power Density ◽  
Inas Quantum Dots ◽  
Different Temperatures ◽  
Scanning Line ◽  
Pl Intensity ◽  
Inas Quantum Dot ◽  
Set Of Points ◽  
Low Dispersion

AbstractThe photoluminescence spectra and its homogeneity for InAs quantum dots (QDs) embedded into In0.15Ga0.85As/GaAs quantum well (QW) structures with QDs grown at different temperatures (470-535°C) have been investigated at 300 K. Photoluminescence (PL) spectra along the scanning line crossed the wafers were measured at 300 K in a set of points on the QD structures under the excitation of the 804 nm line of a solid state IR laser at an excitation power density of 100 W/cm2. In QD structures with InAs QDs grown at 470°C the low integrated PL intensity, the high dispersion of QD sizes in ensemble and, as a result, the large value of FWHM (50-70meV), but the low dispersion of QD ensemble parameters along the line crossed the structures have been detected. In QD structures grown at high temperatures 490-535 °C the high integrated PL intensity, the low dispersion of QD sizes in ensemble and, as a result, less values of FWHM, but the essential dispersion of QD ensemble parameters along the line crossed the structures have been revealed. The reasons of these types of PL nonhomogeneity have been discussed.

scholarly journals Near Infrared Spectra of 103 Bright Be Stars

1987 ◽  
Vol 92 ◽  
pp. 237-238
Author(s):  
Y. Andrillat
Keyword(s):  
Spectral Range ◽  
Infrared Spectra ◽  
Near Infrared ◽  
High Dispersion ◽  
Be Stars ◽  
Near Infrared Spectra ◽  
Low Dispersion

We have observed 103 bright Be stars in the near infrared up to 10500 A with a dispersion of 230 and 50 A mm-1. The observations were performed with a Reticon (1024 diodes) attached to the ROUCAS spectrograph at the 193 cm telescope of the Haute Provence Observatory.In this spectral range, the Be stars are characterized by the lines of HI (Paschen series), 0I(7772-74-75, 8446 A), CaII(8542, 8662, 8498 A), FeII(7712, 9997 A) and NI(8686-83-80, 8719-12-03, 8629 A).On our spectra, the CaII triplet is always blended with P13, P15, P16, and only the enhancement of these lines permits to conclude to the CaII presence. The 0I 8446 A is perturbed by the Paschen lines P17 and P18 (low dispersion spectra) and P18 (high dispersion spectra). The NI 8686-83-80 A lines also perturb the P13 profile.

scholarly journals The band spectra of the alkaline earth halides. I.—CaF, SrF

1929 ◽  
Vol 122 (789) ◽  
pp. 161-188 ◽  
Keyword(s):  
Alkaline Earth ◽  
High Dispersion ◽  
Molecular Weights ◽  
Quantum Analysis ◽  
Alkaline Earths ◽  
Band Spectra ◽  
Low Dispersion ◽  
Selection Of ◽  
Made In ◽  
Alkaline Earth Halides

Band spectra of the alkaline earth halides were familiar to the earliest spectroscopic workers. Most of these spectra can be produced in both the flame and arc. The fluorides of calcium, strontium and barium all give interesting groups of bands which present obvious regularities, and these have been measured under high dispersion by several observers. The chlorides, bromides, and iodides have not been measured with such precision, although from time to time low dispersion measurements seem to have been made. In 1921 Datta made a systematic study of the fluorides of calcium, strontium and barium, and, added to these, data of the bands of magnesium fluoride. He gives an excellent plate of photographs of all these spectra and it has, therefore, not been considered necessary to reproduce any spectrograms in the present paper. Constant reference will, however, be made to this plate. Datta’s work was principally directed to the discovery of numerical relationships between the molecular weights and corresponding band spectra of these similar compounds. With this in view he labelled the band groups in each spectrum A 1 , A 2 , A 3 , ..., B 1 B 2 , B 3 , ..., C 1 , C 2 , C 3 , etc., so that analogous groups in the spectra of the various molecules should have the same designation. His selection of analogous spectra was largely based on their general appearance, and Datta gives several numerical relationships of an empirical character on the basis of this assignment. This work was completed before the applica­tion of the quantum theory to band spectra became prevalent, and it, therefore, needs revision in the light of our present knowledge. For convenience, how­ ever, Datta’s designation of the spectra by these letters will be used in referring to them. Mecke has recently made a quantum analysis of many of these bands and recognised distinct band systems in the fluorides of all the alkaline earths. He has expressed these systems by formulæ of the usual type, and discussed the band structure, the doublet separation, and the vibration frequency shown by this series of similar molecules. The present paper is a continuation and extension of Mecke’s work on the analysis of these spectra. The whole of the known band spectra of the fluorides of Mg, Ca, Sr, and Ba have been completely analysed and ordered in regard to their gross structure.

scholarly journals The International Ultraviolet Explorer (IUE)

1990 ◽  
Vol 123 ◽  
pp. 35-40
Author(s):  
Yoji Kondo
Keyword(s):  
Spectral Resolution ◽  
High Dispersion ◽  
Geosynchronous Orbit ◽  
Nasa Goddard Space ◽  
Collaborative Program ◽  
International Ultraviolet Explorer ◽  
Goddard Space Flight Center ◽  
The World ◽  
Far Ultraviolet ◽  
Low Dispersion

AbstractThe International Ultraviolet Explorer (IUE) was launched into a geosynchronous orbit on 26 January 1978. It is equipped with a 45-cm mirror and spectrographs operating in the far-ultraviolet (1150–2000 Å) and the mid-ultraviolet (1900–3200 Å) wavelength regions. In a low-dispersion mode, the spectral resolution is some 6–7 Å. In a high-dispersion echelle mode, the resolution is about 0.1 Åat the shortest wavelength and about 0.3 Åat the longest. It is a collaborative program among NASA, ESA and the British SERC. The IUE is operated in real time 16 hours a day from NASA Goddard Space Flight Center near Washing ton, D.C. and 8 hours daily from ESA’s Villafranca groundstation near Madrid, Spain. By the end of 1989, 1870 papers, using IUE observations, have been published in refereed journals. During the same period, over 1700 different astronomers from all over the world used the IUE for their research.

scholarly journals A NEW APPROACH IN ENHANCED BIODEGRADATION OF SPILLED OIL: DEVELOPMENT OF AN OIL DISPERSANT CONTAINING OLEOPHILIC NUTRIENTS

1985 ◽  
Vol 1985 (1) ◽  
pp. 453-462 ◽  
Author(s):  
Robert D. E. Bronchart ◽  
Jan Cadron ◽  
Alain Charlier ◽  
Alain A. R. Gillot ◽  
Willy Verstraete
Keyword(s):  
Pilot Scale ◽  
Co2 Production ◽  
High Dispersion ◽  
Oil Dispersants ◽  
Oil Dispersant ◽  
Air Supply ◽  
Enhanced Biodegradation ◽  
Speed Up ◽  
New Type ◽  
Set Up

ABSTRACT A research program has been set up to develop oil dispersants containing oleophilic nutrients. This new type of dispersant will not only dilute the oil slick into the sea, but also start and speed up the microbial growth around the fine oil droplets, because the nutrients remain at the oil/water interface and are not washed away in the water. Each of these newly synthesized nutrients is made of an oleophilic part (normal paraffine or olefine) and of a hydrophilic moiety (containing nitrogen and or phosphorus). This surfactant-like structure allows it to maintain a good level of dispersing efficiency. The capacity to stimulate biodegradation of the various compounds was evaluated by measuring the microbial CO2 production (mineralization) in a gas train arrangement of 40 channels monitored by a 40-way valve. This guaranteed a constant air supply to each test vial. A practical partition coefficient of the nutrient between oil and water was determined to evaluate its ability to remain at the interphase. The influence of the following parameters on the biodegradation process was studied: Amount and chain length of the oleophilic part and type of nutrient, used as such or incorporated in a dispersant Replacement or no replacement of the water phase prior to degradation, to simulate the washing of nutrients into the sea Dispersing efficiency of HLB of the formulated dispersant These results combined with pilot scale trials led to the formulation of a dispersant which exhibits a high dispersion efficiency and a quick-starting biodegradation of the dispersed crude oil.

Sign in / Sign up

Export Citation Format

Share Document