12,951 research outputs found
Growth rings in tropical trees : role of functional traits, environment, and phylogeny
Acknowledgments Financial support of the Centre National de la Recherche Scientifique (USR 3330), France, and from the Rufford Small Grants Foundation (UK) is acknowledged. We thank the private farmers and coffee plantation companies of Kodagu for providing permissions and logistical support for this project. We are grateful to N. Barathan for assistance with slide preparation and data entry, S. Aravajy for botanical assistance, S. Prasad and G. Orukaimoni for technical inputs, and A. Prathap, S. Shiva, B. Saravana, and P. Shiva for field assistance. The corresponding editor and three anonymous reviewers provided insightful comments that improved the manuscript.Peer reviewedPostprin
Overt responses during covert orienting.
A distributed network of cortical and subcortical brain areas controls our oculomotor behavior. This network includes the superior colliculus (SC), which coordinates an ancient visual grasp reflex via outputs that ramify widely within the brainstem and spinal cord, accessing saccadic and other premotor and autonomic circuits. In this Review, we discuss recent results correlating subliminal SC activity in the absence of saccades with diverse components of the visual grasp reflex, including neck and limb muscle recruitment, pupil dilation, and microsaccade propensity. Such subtle manifestations of covert orienting are accessible in the motor periphery and may provide the next generation of oculomotor biomarkers in health and disease
The high-pressure behavior of CaMoO4
We report a high-pressure study of tetragonal scheelite-type CaMoO4 up to 29
GPa. In order to characterize its high-pressure behavior, we have combined
Raman and optical-absorption measurements with density-functional theory
calculations. We have found evidence of a pressure-induced phase transition
near 15 GPa. Experiments and calculations agree in assigning the high-pressure
phase to a monoclinic fergusonite-type structure. The reported results are
consistent with previous powder x-ray-diffraction experiments, but are in
contradiction with the conclusions obtained from earlier Raman measurements,
which support the existence of more than one phase transition in the pressure
range covered by our studies. The observed scheelite-fergusonite transition
induces significant changes in the electronic band gap and phonon spectrum of
CaMoO4. We have determined the pressure evolution of the band gap for the low-
and high-pressure phases as well as the frequencies and pressure dependences of
the Raman-active and infrared-active modes. In addition, based upon
calculations of the phonon dispersion of the scheelite phase, carried out at a
pressure higher than the transition pressure, we propose a possible mechanism
for the reported phase transition. Furthermore, from the calculations we
determined the pressure dependence of the unit-cell parameters and atomic
positions of the different phases and their room-temperature equations of
state. These results are compared with previous experiments showing a very good
agreement. Finally, information on bond compressibility is reported and
correlated with the macroscopic compressibility of CaMoO4. The reported results
are of interest for the many technological applications of this oxide.Comment: 36 pages, 10 figures, 8 table
Observation of Sex Chromatin in Exhumed Bones, Evaluation of their Diagnosis Value
Munoz, P (Munoz, Patricia); Roa, I (Roa, Ignacio). Univ Talca, Dept Ciencias Basicas Biomed, Talca, ChileObservation of sexual chromatin has shown to be very helpful in gender forensic diagnosis. In the present study we analyzed the diagnosis performance of the method in, non-treated or treated with conventional bone techniques, exhumed bone pieces. We used long bones of male and female individuals, the method applied is described in Suazo et al. (2010). In the non-treated exhumed pieces, the general accuracy of the method was 75%, while in the treated pieces the method was inapplicable due to the lack of cells in the tissue. Our results suggest that it is possible to determine the sex of aged human bones buried under different conditions through a fast and simple histological method, but the treatment with physical and chemical means eliminates the remaining cells in the bone tissue
Forging, textures, and deformation systems in a B2 FeAl alloy
High-temperature forging experiments have been carried out by axial compression testing on a Fe-41Al-2Cr alloy in order to determine the deformation systems operating under such high-speed, high-temperature conditions, and to examine the textures produced by such deformation and during subsequent annealing to recrystallize. Deformation is deduced to take place by the operation of 〈111〉 {110} and 〈111〉{112} slip systems at low temperatures and by 〈100〉{001} and 〈100〉{011} slip systems at high temperatures, with the formation of the expected strong 〈111〉 textures. The examination of the weak 〈100〉 texture component is critical to distinguishing the operating slip system. Both texture and dislocation analyses are consistent with the operation of these deformation systems. Recrystallization takes place extremely quickly at high temperatures (above 800 °C), that is within seconds after deformation and also dynamically during deformation itself. Recrystallization changes the texture such that 〈100〉 textures superimpose on the deformation texture. The flow stress peak observed during forging is found at a very high temperature. Possible origins of the peak are examined in terms of the operating slip system
Dominant negative phenotype of Bacillus thuringiensis Cry1Ab, Cry11Aa and Cry4Ba mutants suggest hetero-oligomer formation among different Cry toxins.
Background - Bacillus thuringiensis Cry toxins are used worldwide in the control of different insect pests important in agriculture or in human health. The Cry proteins are pore-forming toxins that affect the midgut cell of target insects. It was shown that non-toxic Cry1Ab helix a-4 mutants had a dominant negative (DN) phenotype inhibiting the toxicity of wildtype Cry1Ab when used in equimolar or sub-stoichiometric ratios (1:1, 0.5:1, mutant:wt) indicating that oligomer formation is a key step in toxicity of Cry toxins. Methodology/Principal Findings - The DN Cry1Ab-D136N/T143D mutant that is able to block toxicity of Cry1Ab toxin, was used to analyze its capacity to block the activity against Manduca sexta larvae of other Cry1 toxins, such as Cry1Aa, Cry1Ac, Cry1Ca, Cry1Da, Cry1Ea and Cry1Fa. Cry1Ab-DN mutant inhibited toxicity of Cry1Aa, Cry1Ac and Cry1Fa. In addition, we isolated mutants in helix a-4 of Cry4Ba and Cry11Aa, and demonstrate that Cry4Ba-E159K and Cry11Aa-V142D are inactive and completely block the toxicity against Aedes aegypti of both wildtype toxins, when used at sub-stoichiometric ratios, confirming a DN phenotype. As controls we analyzed Cry1Ab-R99A or Cry11Aa-E97A mutants that are located in helix a-3 and are affected in toxin oligomerization. These mutants do not show a DN phenotype but were able to block toxicity when used in 10:1 or 100:1 ratios (mutant:wt) probably by competition of binding with toxin receptors. Conclusions/Significance - We show that DN phenotype can be observed among different Cry toxins suggesting that may interact in vivo forming hetero-oligomers. The DN phenotype cannot be observed in mutants affected in oligomerization, suggesting that this step is important to inhibit toxicity of other toxin
A radio and infrared exploration of the Cygnus X-3 environments
To confirm, or rule out, the possible hot spot nature of two previously
detected radio sources in the vicinity of the Cygnus X-3 microquasar.
We present the results of a radio and near infrared exploration of the
several arc-minute field around the well known galactic relativistic jet source
Cygnus X-3 using the Very Large Array and the Calar Alto 3.5~m telescope.
The data this paper is based on do not presently support the hot spot
hypothesis. Instead, our new observations suggest that these sources are most
likely background or foreground objects. Actually, none of them appears to be
even barely extended as would be expected if they were part of a bow shock
structure. Our near infrared observations also include a search for extended
emission in the Bracket (2.166 m) and (2.122 m)
lines as possible tracers of shocked gas in the Cygnus X-3 surroundings. The
results were similarly negative and the corresponding upper limits are
reported.Comment: Accepted for publication in A&A; 5 pages, 4 figure
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