535 research outputs found
Pesticide resistance in Plutella xylostella (Lepidoptera: Plutellidae) populations from Togo and Benin
Published online: 17 August 2016The diamondback moth, Plutella xylostella (L.) is the major insect pest of cabbage crops in Togo and Benin. For control, farmers very often resort to spraying chemical insecticides at high dosages with frequent applications. Bioassays were carried out on three populations of P. xylostella, two from Togo (Kara and Dapaong) and one from Benin (Cotonou), to assess their level of susceptibility to currently used insecticides. A reference strain of P. xylostella from Matuu in Kenya was used as a control. In the laboratory, three insecticide representatives of different chemical families (deltamethrin, chlorpyrifos ethyl and spinosad) were assayed against third instar larvae of P. xylostella. Results revealed that P. xylostella populations from Dapaong, Kara and Cotonou were more resistant to deltamethrin (13 to 59-fold at LC50 level, 149 to 1772-fold at LC90 level) and chlorpyrifos ethyl (5 to 15-fold at LC50 level, 9 to 885-fold at LC90 level) than the reference strain. Spinosad was more toxic to P. xylostella populations than the other insecticides with LC50 and LC90 values less than 1 μg/ml and 15 μg/ml, respectively. However, the population from Cotonou appeared significantly more resistant to spinosad compared to the reference strain. These results are discussed in the light of developing an integrated pest management
strategy for reducing the selection pressure of spinosad
Integral functions of marine vertebrates in the ocean carbon cycle and climate change mitigation
In the last decade, the ocean has absorbed a quarter of the Earth’s greenhouse gas emissions through the
carbon (C) cycle, a naturally occurring process. Aspects of the ocean C cycle are now being incorporated
into climate change mitigation and adaptation plans. Currently, too little is known about marine vertebrate
C functions for their inclusion in policies. Fortunately, marine vertebrate biology, behavior, and ecology
through the lens of C and nutrient cycling and flux is an emerging area of research that is rich in existing
data. This review uses literature and trusted data sources to describe marine vertebrate C interactions, provides quantification where possible, and highlights knowledge gaps. Implications of better understanding the
integral functions of marine vertebrates in the ocean C cycle include the need for consideration of these functions both in policies on nature-based climate change mitigation and adaptation, and in management of marine vertebrate populations.Thank you to the anonymous reviewers whose insightful suggestions greatly
improved the manuscript. Thank you to Thomas Eikeland Fiska˚ at the University of Agder for his work on the conceptual figures and to Dr. Marion Martin
and Dr. Susanna Huneide Thorbjørnsen for helpful discussions throughout
the preparation of the manuscript. Thanks also to Corallie Hunt for comments
and advice during the early stages of the manuscript preparation. E.M.O.
received support from the Marine Science program within the Research Council of Norway, grant no. 294926 (CODSIZE). H.C.P. was supported by Fulbright
Norway, GRID-Arendal, and the University of Alaska Southeast.Ye
Sodium cationization can disrupt the intramolecular hydrogen bond that mediates the sunscreen activity of oxybenzone
A key decay pathway by which organic sunscreen molecules dissipate harmful UV energy involves excited-state hydrogen atom transfer between proximal enol and keto functional groups. Structural modifications of this molecular architecture have the potential to block ultrafast decay processes, and hence promote direct excited-state molecular dissociation, profoundly affecting the efficiency of an organic sunscreen. Herein, we investigate the binding of alkali metal cations to a prototype organic sunscreen molecule, oxybenzone, using IR characterization. Mass-selective IR action spectroscopy was conducted at the free electron laser for infrared experiments, FELIX (600-1800 cm-1), on complexes of Na+, K+ and Rb+ bound to oxybenzone. The IR spectra reveal that K+ and Rb+ adopt binding positions away from the key OH intermolecular hydrogen bond, while the smaller Na+ cation binds directly between the keto and enol oxygens, thus breaking the intramolecular hydrogen bond. UV laser photodissociation spectroscopy was also performed on the series of complexes, with the Na+ complex displaying a distinctive electronic spectrum compared to those of K+ and Rb+, in line with the IR spectroscopy results. TD-DFT calculations reveal that the origin of the changes in the electronic spectra can be linked to rupture of the intramolecular bond in the sodium cationized complex. The implications of our results for the performance of sunscreens in mixtures and environments with high concentrations of metal cations are discussed
Pretransplant characteristics of kidney transplant recipients that predict posttransplant outcome
Better characterization of the potential kidney transplant recipient using novel biomarkers, for example, pretransplant plasma endotrophin, will lead to improved outcome after transplantation. This mini-review will focus on current knowledge about pretransplant recipients’ characteristics, biomarkers, and immunology. Clinical characteristics of recipients including age, obesity, blood pressure, comorbidities, and estimated survival scores have been introduced for prediction of recipient and allograft survival. The pretransplant immunologic risk assessment include histocompatibility leukocyte antigens (HLAs), anti-HLA donor-specific antibodies, HLA-DQ mismatch, and non-HLA antibodies. Recently, there has been the hope that pretransplant determination of markers can further improve the prediction of posttransplant complications, both short-term and long-term outcomes including rejections, allograft loss, and mortality. Higher pretransplant plasma endotrophin levels were independently associated with posttransplant acute allograft injury in three prospective European cohorts. Elevated numbers of non-synonymous single-nucleotide polymorphism mismatch have been associated with increased allograft loss in a multivariable analysis. It is concluded that there is a need for integration of clinical characteristics and novel molecular and immunological markers to improve future transplant medicine to reach better diagnostic decisions tailored to the individual patient
Entanglement and localization of wavefunctions
We review recent works that relate entanglement of random vectors to their
localization properties. In particular, the linear entropy is related by a
simple expression to the inverse participation ratio, while next orders of the
entropy of entanglement contain information about e.g. the multifractal
exponents. Numerical simulations show that these results can account for the
entanglement present in wavefunctions of physical systems.Comment: 6 pages, 4 figures, to appear in the proceedings of the NATO Advanced
Research Workshop 'Recent Advances in Nonlinear Dynamics and Complex System
Physics', Tashkent, Uzbekistan, 200
Crime fiction, South Africa : a critical introduction
Crime fiction is an emergent category in South African literary studies. This introduction positions South African crime fiction and its scholarship in a global lineage of crime and detective fiction. The survey addresses the question of its literary status as ‘highbrow’ or ‘lowbrow’. It also identifies and describes two distinct sub-genres of South African crime fiction: the crime thriller novel; and the literary detective novel. The argument is that South African crime fiction exhibits a unique capacity for social analysis: a capacity which is being optimised by authors and interrogated by scholar
Frequency behavior of Raman coupling coefficient in glasses
Low-frequency Raman coupling coefficient of 11 different glasses is
evaluated. It is found that the coupling coefficient demonstrates a universal
linear frequency behavior near the boson peak maximum and a superlinear
behavior at very low frequencies. The last observation suggests vanishing of
the coupling coefficient when frequency tends to zero. The results are
discussed in terms of the vibration wavefunction that combines features of
localized and extended modes.Comment: 8 pages, 9 figure
Soft Photons in Hadron-Hadron Collisions: Synchrotron Radiation from the QCD Vacuum?
We discuss the production of soft photons in high energy hadron-hadron
collisions. We present a model where quarks and antiquarks in the hadrons emit
``synchrotron light'' when being deflected by the chromomagnetic fields of the
QCD vacuum, which we assume to have a nonperturbative structure. This gives a
source of prompt soft photons with frequencies in the c.m.
system of the collision in addition to hadronic bremsstrahlung. In comparing
the frequency spectrum and rate of ``synchrotron'' photons to experimental
results we find some supporting evidence for their existence. We make an
exclusive--inclusive connection argument to deduce from the ``synchrotron''
effect a behaviour of the neutron electric formfactor proportional
to for . We find this to be consistent with
available data. In our view, soft photon production in high energy
hadron-hadron and lepton-hadron collisions as well as the behaviour of
electromagnetic hadron formfactors for low are thus sensitive probes of
the nonperturbative structure of the QCD vacuum.Comment: Heidelberg preprint HD-THEP-94-36, 31 pages, LaTeX + ZJCITE.sty
(included), 12 figures appended as uuencoded compressed ps-fil
Lepton Flavour Violating Leptonic/Semileptonic Decays of Charged Leptons in the Minimal Supersymmetric Standard Model
We consider the leptonic and semileptonic (SL) lepton flavour violating (LFV)
decays of the charged leptons in the minimal supersymmetric standard model
(MSSM). The formalism for evaluation of branching fractions for the SL LFV
charged-lepton decays with one or two pseudoscalar mesons, or one vector meson
in the final state, is given. Previous amplitudes for the SL LFV charged-lepton
decays in MSSM are improved, for instance the -penguin amplitude is
corrected to assure the gauge invariance. The decays are studied not only in
the model-independent formulation of the theory in the frame of MSSM, but also
within the frame of the minimal supersymmetric SO(10) model within which the
parameters of the MSSM are determined. The latter model gives predictions for
the neutrino-Dirac Yukawa coupling matrix, once free parameters in the model
are appropriately fixed to accommodate the recent neutrino oscillation data.
Using this unambiguous neutrino-Dirac Yukawa couplings, we calculate the LFV
leptonic and SL decay processes assuming the minimal supergravity scenario. A
very detailed numerical analysis is done to constrain the MSSM parameters.
Numerical results for SL LFV processes are given, for instance for tau -> e
(mu) pi0, tau -> e (mu) eta, tau -> e (mu) eta', tau -> e (mu) rho0, tau -> e
(mu) phi, tau -> e (mu) omega, etc.Comment: 36 pages, 3 tables, 5 .eps figure
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