262 research outputs found
Vertical movement of adult rusty grain beetles, Cryptolestes ferrugineus, in stored corn and wheat at uniform moisture content
Vertical movement and distribution of Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) adults in stored wheat and corn were studied in small (0.1 x 0.1 x 1 m) and large (0.6 m diameter and 1.12 m high) columns. The adults were introduced at the top, middle, and bottom of the small columns with a uniform moisture content (wheat: 14.5 ± 0.1%, corn 13.5 ± 0.1%, 15.5 ± 0.1%, and 17.5 ± 0.1%) at 27.5 ± 0.5°C. When introduced at different locations, adults showed a similar distribution in stored grain bulk with a uniform temperature and moisture content of 14.5% for wheat or 15.5% for corn. Adults showed downward displacement over 24 h when corn moisture was lower than 15.5%, but they did not show downward displacement when moisture content was 17.5%. The upward or downward movement might partially be caused by a drift effect due to beetles sliding between seeds and the displacement of the adults might be the combined effect of walking and falling during their movement. The hydrophilic behavior plus the drift effect explain why the beetles had a faster downward dispersal in the 13.5% corn than in the 15.5% and 17.5% corn and a slight upward displacement in 17.5% corn because they were more active at the lower moisture contents. Adults had a similar movement and distribution in both the small and large wheat columns
Theoretical analysis of the electronic structure of the stable and metastable c(2x2) phases of Na on Al(001): Comparison with angle-resolved ultra-violet photoemission spectra
Using Kohn-Sham wave functions and their energy levels obtained by
density-functional-theory total-energy calculations, the electronic structure
of the two c(2x2) phases of Na on Al(001) are analysed; namely, the metastable
hollow-site structure formed when adsorption takes place at low temperature,
and the stable substitutional structure appearing when the substrate is heated
thereafter above ca. 180K or when adsorption takes place at room temperature
from the beginning. The experimentally obtained two-dimensional band structures
of the surface states or resonances are well reproduced by the calculations.
With the help of charge density maps it is found that in both phases, two
pronounced bands appear as the result of a characteristic coupling between the
valence-state band of a free c(2x2)-Na monolayer and the
surface-state/resonance band of the Al surfaces; that is, the clean (001)
surface for the metastable phase and the unstable, reconstructed "vacancy"
structure for the stable phase. The higher-lying band, being Na-derived,
remains metallic for the unstable phase, whereas it lies completely above the
Fermi level for the stable phase, leading to the formation of a
surface-state/resonance band-structure resembling the bulk band-structure of an
ionic crystal.Comment: 11 pages, 11 postscript figures, published in Phys. Rev. B 57, 15251
(1998). Other related publications can be found at
http://www.rz-berlin.mpg.de/th/paper.htm
Modelos analĂticos do crescimento populacional de Sitophilus zeamais em trigo armazenado
Influence of band width on the scattered ion yield spectra of a He + Ion by resonant or quasi-resonant charge exchange neutralization
The influence of the band structure, especially the bandwidth, on the scattered ion yield spectra of a He+ ion by the resonant or quasi-resonant neutralization was theoretically examined using quantum rate equations. When calculating the scattered ion yield spectra of He+ to simulate the experimental data, we observed that the band structure, especially the bandwidth, had a strong influence on the spectra at relatively low incident He+ ion energies of less than several hundred eV. Through many simulations, it was determined that theoretical calculations that include bandwidth calculation can simulate or reproduce the experimentally observed spectra of He+-In, He+-Ga, and He+-Sn systems. In contrast, simulations not including bandwidth simulation could neither reproduce nor account for such spectra. Furthermore, the calculated ion survival probability (ISP) at low incident ion energies tended to decrease with increasing bandwidth. This decrease in ISP probably corresponds to the relatively small scattered ion yield usually observed at low incident ion energies. Theoretically, such a decrease indicates that a He+ ion with a low incident energy can be easily neutralized on the surface when the bandwidth is large
Applications of paleomagnetism in the volcanic field: A case study of the Unzen Volcano, Japan
Post-harvest management and associated food losses and by-products of cassava in southern Ethiopia
Improved (high yield and disease resistant) cassava varieties were introduced into Ethiopia around the onset of the twenty-first century, as a potential food security crop. At present, limited information is available from the country on post-production aspects of the value chain (VC) and related food losses. The lack of such data prevents policymakers and VC actors from taking steps towards improving VC efficiencies, which can have a significant impact on livelihoods and food security. The focus of this study was to examine the prevailing post-harvest practices in the cassava VC in southern Ethiopia and quantify the extent of food losses and associated by-products in the framework of the recently developed âfood loss and waste protocolâ. The majority of the cassava in the study area was processed into dry chips and milled into a composite flour with teff and maize to prepare the staple bread (injera). âCritical loss pointsâ were during sun-drying (4%) and stockpiling at farm and marketplace (30â50%). Insect pest damage was primarily responsible for food losses at farm and market level. The most important insect species infesting dry cassava were identified during the survey. As far as the by-products were concerned, the ratio of leaf:wood (stem and stump):starchy root on a dry matter basis at harvest was 1:6:10. Further emphasis should be on improving processing and storage technologies to reduce food losses and the better recovery and utilisation of by-products, especially the leaves of cassava, which could be a potential source of protein in human diets
CaracterĂsticas fĂsico-quĂmicas de grĂŁos de milho atacados por Sitophilus zeamais durante o armazenamento
- âŠ