197 research outputs found
Lack of correlation between constitutive and induced resistance to a herbivore in crucifer plants: real or flawed by experimental methods?
The correlation between constitutive and induced resistance to herbivores in plants has long been of interest to evolutionary biologists, and various approaches to determining levels of resistance have been used in this field of research. In this study, we examined the relationship between constitutive and induced resistance to the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), in 11 closely related species of wild crucifers. We assessed the survival, development, and reproduction of the test insects and calculated their intrinsic rate of increase as an indicator of constitutive and induced resistance for the plants. We used larvae of P. xylostella and jasmonic acid as elicitors of the induced response. We failed to find a correlation between constitutive and induced resistance in these crucifer plants when the induction of resistance was initiated by either herbivory or jasmonic acid application. Analysis of the results suggests that the failure to detect a relationship between the two types of resistance could be caused by flaws in measuring constitutive resistance, which was apparently confounded with induced resistance. We discuss the difficulties and pitfalls in measuring constitutive resistance and ways to improve the methodology in investigating the relationships between constitutive and induced resistance in plant
Perturbative Calculation of Quasinormal Modes of --Dimensional Black Holes
We study analytically quasinormal modes in a wide variety of black hole
spacetimes, including --dimensional asymptotically flat spacetimes and
non-asymptotically flat spacetimes (particular attention has been paid to the
four dimensional case). We extend the analytical calculation to include
first-order corrections to analytical expressions for quasinormal mode
frequencies by making use of a monodromy technique. All possible type
perturbations are included in this paper. The calculation performed in this
paper show that systematic expansions for uncharged black holes include
different corrections with the ones for charged black holes. This difference
makes them have a different --dependence relation in the first-order
correction formulae. The method applied above in calculating the first-order
corrections of quasinormal mode frequencies seems to be unavailable for black
holes with small charge. This result supports the Neitzke's prediction. On what
concerns quantum gravity we confirm the view that the in
Schwarzschild seems to be nothing but some numerical coincidences.Comment: 49 pages, 5 figure
Linear Rashba Model of a Hydrogenic Donor Impurity in GaAs/GaAlAs Quantum Wells
The Rashba spin-orbit splitting of a hydrogenic donor impurity in GaAs/GaAlAs quantum wells is investigated theoretically in the framework of effective-mass envelope function theory. The Rashba effect near the interface between GaAs and GaAlAs is assumed to be a linear relation with the distance from the quantum well side. We find that the splitting energy of the excited state is larger and less dependent on the position of the impurity than that of the ground state. Our results are useful for the application of Rashba spin-orbit coupling to photoelectric devices
Helium bubble formation in ultrafine and nanocrystalline tungsten under different extreme conditions
We have investigated the effects of helium ion irradiation energy and sample temperature on the performance of grain boundaries as helium sinks in ultrafine grained and nanocrystalline tungsten. Irradiations were performed at displacement and non-displacement energies and at temperatures above and below that required for vacancy migration. Microstructural investigations were performed using Transmission Electron Microscopy (TEM) combined with either in-situ or ex-situ ion irradiation. Under helium irradiation at an energy which does not cause atomic displacements in tungsten (70 eV), regardless of temperature and thus vacancy migration conditions, bubbles were uniformly distributed with no preferential bubble formation on grain boundaries. At energies that can cause displacements, bubbles were observed to be preferentially formed on the grain boundaries only at high temperatures where vacancy migration occurs. Under these conditions, the decoration of grain boundaries with large facetted bubbles occurred on nanocrystalline grains with dimensions less than 60 nm. We discuss the importance of vacancy supply and the formation and migration of radiation-induced defects on the performance of grain boundaries as helium sinks and the resulting irradiation tolerance of ultrafine grained and nanocrystalline tungsten to bubble formatio
Confront Holographic QCD with Regge Trajectories of vectors and axial-vectors
We derive the general 5-dimension metric structure of the system in
type II superstring theory, and demonstrate the physical meaning of the
parameters characterizing the 5-dimension metric structure of the
\textit{holographic} QCD model by relating them to the parameters describing
Regge trajectories. By matching the spectra of vector mesons with
deformed soft-wall model, we find that the spectra of vector mesons
can be described very well in the soft-wall model, i.e,
soft-wall model. We then investigate how well the soft-wall
model can describe the Regge trajectory of axial-vector mesons . We find
that the constant component of the 5-dimension mass square of axial-vector
mesons plays an efficient role to realize the chiral symmetry breaking in the
vacuum, and a small negative correction in the 5-dimension mass square is
helpful to realize the chiral symmetry restoration in high excitation states.Comment: 9 pages, 3 figure and 3 tables, one section adde
Top A_FB at the Tevatron vs. charge asymmetry at the LHC in chiral U(1) flavor models with flavored Higgs doublets
We consider the top forward-backward (FB) asymmetry at the Tevatron and top
charge asymmetry at the LHC within chiral U(1)^\prime models with
flavor-dependent U(1)^\prime charges and flavored Higgs fields, which were
introduced in the ref. [65]. The models could enhance not only the top
forward-backward asymmetry at Tevatron, but also the top charge asymmetry at
LHC, without too large same-sign top pair production rates. We identify
parameter spaces for the U(1)^\prime gauge boson and (pseudo)scalar Higgs
bosons where all the experimental data could be accommodated, including the
case with about 125 GeV Higgs boson, as suggested recently by ATLAS and CMS.Comment: 11 pages, 6 figures, figures and discussion adde
Treatment Guidance for Patients With Lung Cancer During the Coronavirus 2019 Pandemic
The global coronavirus disease 2019 pandemic continues to escalate at a rapid pace inundating medical facilities and creating substantial challenges globally. The risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in patients with cancer seems to be higher, especially as they are more likely to present with an immunocompromised condition, either from cancer itself or from the treatments they receive. A major consideration in the delivery of cancer care during the pandemic is to balance the risk of patient exposure and infection with the need to provide effective cancer treatment. Many aspects of the SARS-CoV-2 infection currently remain poorly characterized and even less is known about the course of infection in the context of a patient with cancer. As SARS-CoV-2 is highly contagious, the risk of infection directly affects the cancer patient being treated, other cancer patients in close proximity, and health care providers. Infection at any level for patients or providers can cause considerable disruption to even the most effective treatment plans. Lung cancer patients, especially those with reduced lung function and cardiopulmonary comorbidities are more likely to have increased risk and mortality from coronavirus disease 2019 as one of its common manifestations is as an acute respiratory illness. The purpose of this manuscript is to present a practical multidisciplinary and international overview to assist in treatment for lung cancer patients during this pandemic, with the caveat that evidence is lacking in many areas. It is expected that firmer recommendations can be developed as more evidence becomes available
Pressure-Based and Potential-Based Differential Quadrature Procedures for Free Vibration of Circular Plates in Contact with Fluid
Chondrules – ubiquitous chondritic solids tracking the evolution of the solar protoplanetary disk
Research on Free Vibration Frequency Characteristics of Rotating Functionally Graded Material Truncated Conical Shells with Eccentric Functionally Graded Material Stringer and Ring Stiffeners
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