250 research outputs found
NF00-425 Resistance Management for European Corn Borer and Bt Transgenic Corn: Refuge Design and Placement (Revised October 2002)
One of the key issues surrounding the use of Bt transgenic corn hybrids is resistance management. These corn hybrids have been engineered to produce a version of the insecticidal protein from the naturally occurring soil bacterium, Bacillus thuringiensis (Bt), that is toxic to European corn borers and a few other insects. This NebFact discusses the important principles of resistance management for European corn borer and Bt corn and refuge considerations
Kink band instability and propagation in layered structures
A recent two-dimensional prototype model for the initiation of kink banding in compressed layered structures is extended to embrace the two propagation mechanisms of band broadening and band progression. As well as interlayer friction, overburden pressure and layer bending energy, the characteristics of transverse layer compressibility and foundation stiffness are now included. Experiments on constrained layers of paper show good agreement with the predictions of angle of orientation, kink band width and post-kink load-deflection response obtained from the model
Cylindrical shell buckling: a characterization of localization and periodicity
A hypothesis for the prediction of the circumferential wavenumber of buckling ofthe thin axially-compressed cylindrical shell is presented, based on the addition of a length effect to the classical (Koiter circle) critical load result. Checks against physical and numerical experiments, both by direct comparison of wavenumbers and via a scaling law, provide strong evidence that the hypothesis is correct
The Wadi Faynan Project, Southern Jordan: a Preliminary Report on Geomorphology and Landscape Archaeology
Reproduced with permission of the publisher. © 1997 Council for British Research in the Levant. Details of the publication are available at: http://www.cbrl.org.uk/Publications/publications_default.shtmThe Wadi Faynan Project of the British Institute at Amman for Archaeology and History (BIAAH) has as its principal objective the provision of a detailed case study in the relationship between environmental change and human history in the arid zone, from prehistory to the present day. This report describes the preliminary findings of an initial campaign of fieldwork in geomorphology and landscape archaeology conducted by an inter-disciplinary team in 1996. A preliminary sequence of fluvial events has been established, represented by the Ghuwayr and Shayqar Beds dated to the Late Pleistocene, and the Faynan and Dana Beds dated to the Holocene. Methodologies have been trialed for recording, dating and interpreting the ancient field system assumed to be of Nabataean, Roman and Byzantine date; initial findings confirm its longevity of use and complexity of purpose. There are also indications that floodwater farming began in the Wadi Faynan in the Chalcolithic or Early Bronze Ag
Kinetics of the reduction of wilt-type and mutant cytochrome c-550 by methylamin dehydrogenase and amicyanin from thiobacillus-versutus
Macromolecular Biochemistr
Optimum design and testing of a postbuckled stiffened panel
The efficient, industrially used, linear elastic
preliminary design software VICONOPT is employed
to design a stiffened panel with a post-buckled
reserve of strength. The initial buckling mode is a
local skin mode in longitudinal compression with
allowance being made for the effects of an initial
overall imperfection. The resulting panel has been
analyzed using the non-linear FE package ABAQUS
and four laboratory specimens have been tested to
failure. The similarity of the experimental failure with
the VICONOPT and ABAQUS predictions suggests
that VICONOPT can give a satisfactory preliminary
design. While neither model matches completely the
boundary conditions found in a real aircraft
compression panel, it is suggested that the
VICONOPT model may be a better representation
than either the ABAQUS model or the experimental
tests
Characterization of mutant met100lys of cytochrome c-550 from thibacillus-versutus with Lysine-histidine heme ligation
Macromolecular Biochemistr
Granular discharge and clogging for tilted hoppers
We measure the flux of spherical glass beads through a hole as a systematic
function of both tilt angle and hole diameter, for two different size beads.
The discharge increases with hole diameter in accord with the Beverloo relation
for both horizontal and vertical holes, but in the latter case with a larger
small-hole cutoff. For large holes the flux decreases linearly in cosine of the
tilt angle, vanishing smoothly somewhat below the angle of repose. For small
holes it vanishes abruptly at a smaller angle. The conditions for zero flux are
discussed in the context of a {\it clogging phase diagram} of flow state vs
tilt angle and ratio of hole to grain size
Archaeology and Desertification in the Wadi Faynan: the Fourth (1999) Season of the Wadi Faynan Landscape Survey
Reproduced with permission of the publisher. © 2000 Council for British Research in the Levant. Details of the publication are available at: http://www.cbrl.org.uk/Publications/publications_default.shtmThis report describes the fourth season of fieldwork by an interdisciplinary team of archaeologists and geographers working together to reconstruct the landscape history of the Wadi Faynan in southern Jordan. The particular focus of the project is the long-term history of inter-relationships between landscape and people, as a contribution to the study of processes of desertification and environmental degradation. The 1999 fieldwork contributed significantly towards the five
Objectives defined for the final two field seasons of the project in 1999 and 2000: to map the archaeology outside the ancient field systems flooring the wadi that have formed the principal focus of the archaeological survey in the previous seasons; to use ethnoarchaeological studies both to reconstruct modern and recent land use and also to yield archaeological signatures of land use to
inform the analysis of the survey data; to complete the survey of ancient field systems and refine understanding of when and how they functioned; to complete the programme of geomorphological and palaeoecological fieldwork, and in particular to refine the chronology of climatic change and human impacts; and to complete the recording and classification of finds
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