3,773 research outputs found
Dark Matter and Yukawa Unification with Massive Neutrinos
We revisit the WMAP dark matter constraints on Yukawa Unification in the
presence of massive neutrinos. The large neutrino mixing indicated by the data
modifies the predictions for the bottom quark mass, and enables Yukawa also for
large , and for positive that were previously disfavoured. As
a result, the allowed parameter space for neutralino dark matter also
increases, particularly for areas with resonant enhancement of the neutralino
relic density.Comment: Proceedings of 4th International Workshop on the Dark Side of the
Universe (DSU 2008), Cairo, June 2008. 7 pages, 4 figure
HepaPlan: a CAD software for planning hepatic surgeries
López-Mir, F.; Naranjo Ornedo, V.; Verdú-Monedero, R.; Morales, S.; Brugger, S.; Pareja, E. (2015). HepaPlan: a CAD software for planning hepatic surgeries. International Journal of Computer Assisted Radiology and Surgery. 10(Suppl 1):S238-S239. http://hdl.handle.net/10251/65381SS238S23910Suppl
Extrapolating non-target risk of Bt crops from laboratory to field
The tiered approach to assessing ecological risk of insect-resistant transgenic crops assumes that lower tier laboratory studies, which expose surrogate non-target organisms to high doses of insecticidal proteins, can detect harmful effects that might be manifested in the field. To test this assumption, we performed meta-analyses comparing results for non-target invertebrates exposed to Bacillus thuringiensis (Bt) Cry proteins in laboratory studies with results derived from independent field studies examining effects on the abundance of non-target invertebrates. For Lepidopteran-active Cry proteins, laboratory studies correctly predicted the reduced field abundance of non-target Lepidoptera. However, laboratory studies incorporating tri-trophic interactions of Bt plants, herbivores and parasitoids were better correlated with the decreased field abundance of parasitoids than were direct-exposure assays. For predators, laboratory tri-trophic studies predicted reduced abundances that were not realized in field studies and thus overestimated ecological risk. Exposure to Coleopteran-active Cry proteins did not significantly reduce the laboratory survival or field abundance of any functional group examined. Our findings support the assumption that laboratory studies of transgenic insecticidal crops show effects that are either consistent with, or more conservative than, those found in field studies, with the important caveat that laboratory studies should explore all ecologically relevant routes of exposure
The motion of the 2D hydrodynamic Chaplygin sleigh in the presence of circulation
We consider the motion of a planar rigid body in a potential flow with
circulation and subject to a certain nonholonomic constraint. This model is
related to the design of underwater vehicles.
The equations of motion admit a reduction to a 2-dimensional nonlinear
system, which is integrated explicitly. We show that the reduced system
comprises both asymptotic and periodic dynamics separated by a critical value
of the energy, and give a complete classification of types of the motion. Then
we describe the whole variety of the trajectories of the body on the plane.Comment: 25 pages, 7 figures. This article uses some introductory material
from arXiv:1109.321
Comparison of the material quality of AlxIn1-xN (x ~ 0-0.50) films deposited on Si (100) and (111) by reactive RF sputtering
Here, we compare the material quality of AlxIn1-xN layers deposited on Si
with different crystallographic orientations, (100) and (111), via
radio-frequency (RF) sputtering. To modulate their Al content, the Al RF power
was varied from 0 to 225 W, whereas the In RF power and deposition temperature
were fixed at 30 W and 300oC, respectively. X-ray diffraction measurements
reveal a c-axis-oriented wurtzite structure with no phase separation regardless
of the Al content (x = 0-0.50), which increases with the Al power supply. The
surface morphology of the AlxIn1-xN layers improves with increasing Al content
and it is similar for samples grown on both Si substrates (the root-mean-square
roughness decreases from 12 nm to 2.5 nm). Furthermore, from TEM images we
notice a similar grain-like columnar morphology and defect density on samples
deposited on both Si substrates under the same conditions. Simultaneously grown
AlxIn1-xN-on-sapphire samples point to a residual n-type carrier concentration
in the 1020-1021 cm-3 range. The optical band gap energy of these layers
evolves from 1.75 eV to 2.56 eV with increasing Al content, consistent with the
blue shift of their low-temperature photoluminescence. In general, the material
quality of the AlxIn1-xN films on Si is similar for both crystallographic
orientations. Nonetheless, samples deposited on sapphire show an improved
structural and morphological characteristic likely due to the lower difference
in lattice constants between the nitride and the sapphire substrate
Bacillus thuringiensis plants expressing Cry1Ac, Cry2Ab and Cry1F are not toxic to the assassin bug, Zelus renardii
Cotton‐ and maize‐producing insecticidal crystal (Cry) proteins from the bacterium, Bacillus thuringiensis (Bt), have been commercialized since 1996. Bt plants are subjected to environmental risk assessments for non‐target organisms, including natural enemies that suppress pest populations. Here, we used Cry1F‐resistant Spodoptera frugiperda (J.E. Smith) and Cry1Ac and Cry2Ab‐resistant Trichoplusia ni (Hübner) as prey for the assassin bug, Zelus renardii (Kolenati), a common predator in maize and cotton fields. In tritrophic studies, we assessed several fitness parameters of Z. renardii when it fed on resistant S. frugiperda that had fed on Bt maize expressing Cry1F or on resistant T. ni that had fed on Bt cotton expressing Cry1Ac and Cry2Ab. Survival, nymphal duration, adult weight, adult longevity and female fecundity of Z. renardii were not different when they were fed resistant‐prey larvae (S. frugiperda or T. ni) reared on either a Bt crop or respective non‐Bt crops. ELISA tests demonstrated that the Cry proteins were present in the plant at the highest levels, at lower levels in the prey and at the lowest levels in the predator. While Z. renardii was exposed to Cry1F and Cry1Ac and Cry2Ab when it fed on hosts that consumed Bt‐transgenic plants, the proteins did not affect important fitness parameters in this common and important predator
Cytomolecular identification of individual wheat-wheat chromosome arm associations in wheat-rye hybrids
Chromosome pairing in the meiotic metaphase I of wheatrye
hybrids has been characterized by sequential genomic
and fluorescent in situ hybridization allowing not only the
discrimination of wheat and rye chromosomes, but also the
identification of the individual wheat and rye chromosome
arms involved in the chromosome associations. The majority
of associations (93.8%) were observed between the wheat
chromosomes. The largest number of wheat-wheat chromosome
associations (53%) was detected between the A and D
genomes, while the frequency of B-D and A-B associations
was significantly lower (32 and 8%, respectively). Among the
A-D chromosome associations, pairing between the 3AL and
3DL arms was observed with the highest frequency, while
the most frequent of all the chromosome associations (0.113/
cell) was found to be the 3DS-3BS. Differences in the pairing
frequency of the individual chromosome arms of wheat-rye
hybrids have been discussed in relation to the homoeologous
relationships between the constituent genomes of
hexaploid wheat
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