2,794 research outputs found
A screen for bacterial endosymbionts in the model organisms Tribolium castaneum, T. confusum, Callosobruchus maculatus, and related species
Reproductive parasites such as Wolbachia are extremely widespread amongst the arthropods and can have a large influence over the reproduction and fitness of their hosts. Undetected infections could thus confound the results of a wide range of studies that focus on aspects of host behavior, reproduction, fitness, and degrees of reproductive isolation. This potential problem has already been underlined by work investigating the incidence of Wolbachia infections in stocks of the model system Drosophila melanogaster. Here we survey a range of lab stocks of further commonly used model arthropods, focusing especially on the flour beetles Tribolium castaneum and Tribolium confusum, the cowpea weevil Callosobruchus maculatus and related species (Coleoptera: Tenebrionidae and Bruchidae). These species are widespread stored product pests so knowledge of infections with symbionts further has potential use in informing biocontrol measures. Beetles were assessed for infection with 3 known microbial reproductive parasites: Wolbachia, Rickettsia, Spiroplasma. Infections with some of these microbes were found in some of the lab stocks studied, although overall infections were relatively rare. The consequences of finding infections in these or other species and the type of previous studies likely to be affected most are discussed
A screen for bacterial endosymbionts in the model organisms Tribolium castaneum, T. confusum, Callosobruchus maculatus, and related species
Reproductive parasites such as Wolbachia are extremely widespread amongst the arthropods and can have a large influence over the reproduction and fitness of their hosts. Undetected infections could thus confound the results of a wide range of studies that focus on aspects of host behavior, reproduction, fitness, and degrees of reproductive isolation. This potential problem has already been underlined by work investigating the incidence of Wolbachia infections in stocks of the model system Drosophila melanogaster. Here we survey a range of lab stocks of further commonly used model arthropods, focusing especially on the flour beetles Tribolium castaneum and Tribolium confusum, the cowpea weevil Callosobruchus maculatus and related species (Coleoptera: Tenebrionidae and Bruchidae). These species are widespread stored product pests so knowledge of infections with symbionts further has potential use in informing biocontrol measures. Beetles were assessed for infection with 3 known microbial reproductive parasites: Wolbachia, Rickettsia, Spiroplasma. Infections with some of these microbes were found in some of the lab stocks studied, although overall infections were relatively rare. The consequences of finding infections in these or other species and the type of previous studies likely to be affected most are discussed
Women's Perspectives on Contraceptive-Induced Amenorrhea in Burkina Faso and Uganda
CONTEXT: Women's concerns about contraceptive-induced menstrual changes can lead to method discontinuation and nonuse, contributing to unmet need for contraception. Research on women's perceptions of amenorrhea related to longer acting methods and in low-income countries is limited. METHODS: Data were from nationally representative household surveys and focus group discussions with women of reproductive age conducted in Burkina Faso and Uganda in 2016-2017. Bivariate cross-tabulations and multivariate logistic regression analyses were used to examine sociodemographic and reproductive characteristics associated with women's attitudes about contraceptive-induced amenorrhea (n=2,673 for Burkina Faso and 2,281 for Uganda); menstrual health determinants were also examined for Burkina Faso. Qualitative data from focus group discussions were analyzed to understand reasons behind women's attitudes and how they influence contraceptive decision making. RESULTS: Sixty-five percent of women in Burkina Faso and 40% in Uganda reported they would choose a method that caused amenorrhea during use. In Burkina Faso, the predicted probability of accepting amenorrhea was higher for women aged 15-19 (compared with older women), living in rural areas, married and cohabiting (compared with never married), currently using a contraceptive method (compared with never users) and from Mossi households (compared with Gourmantché); menstrual health practices were not associated with amenorrhea acceptability. In Uganda, the least wealthy women had the highest predicted probability of accepting amenorrhea (51%). Qualitative analysis revealed a variety of reasons for women's attitudes about amenorrhea and differences by country, but the relationship between these attitudes and contraceptive decision making was similar across countries. CONCLUSIONS: Addressing misconceptions about contraception and menstruation may result in more informed method decision making
Holding on to voters in volatile times: Bonding voters through party links with civil society
Holding on to voters in volatile times: Bonding voters through party links with civil society
The Singularity Threshold of the Nonlinear Sigma Model Using 3D Adaptive Mesh Refinement
Numerical solutions to the nonlinear sigma model (NLSM), a wave map from 3+1
Minkowski space to S^3, are computed in three spatial dimensions (3D) using
adaptive mesh refinement (AMR). For initial data with compact support the model
is known to have two regimes, one in which regular initial data forms a
singularity and another in which the energy is dispersed to infinity. The
transition between these regimes has been shown in spherical symmetry to
demonstrate threshold behavior similar to that between black hole formation and
dispersal in gravitating theories. Here, I generalize the result by removing
the assumption of spherical symmetry. The evolutions suggest that the
spherically symmetric critical solution remains an intermediate attractor
separating the two end states.Comment: 5 pages, 5 figures, 1 table; To be published in Phys. Rev. D.; Added
discussion of initial data; Added figure and reference
Radion and moduli stabilization from induced brane actions in higher-dimensional brane worlds
We consider a 4+N-dimensional brane world with 2 co-dimension 1 branes in an
empty bulk. The two branes have N-1 of their extra dimensions compactified on a
sphere S^(N-1), whereas the ordinary 4 spacetime directions are Poincare
invariant. An essential input are induced stress-energy tensors on the branes
providing different tensions for the spherical and flat part of the branes. The
junction conditions - notably through their extra dimensional components - fix
both the distance between the branes as well as the size of the sphere. As a
result, we demonstrate, that there are no scalar Kaluza-Klein states at all
(massless or massive), that would correspond to a radion or a modulus field of
S^(N-1). We also discuss the effect of induced Einstein terms on the branes and
show that their coefficients are bounded from above, otherwise they lead to a
graviton ghost.Comment: 23 pages, no figures, references added, typos correcte
Theory of coherent acoustic phonons in InGaN/GaN multi-quantum wells
A microscopic theory for the generation and propagation of coherent LA
phonons in pseudomorphically strained wurzite (0001) InGaN/GaN multi-quantum
well (MQW) p-i-n diodes is presented. The generation of coherent LA phonons is
driven by photoexcitation of electron-hole pairs by an ultrafast Gaussian pump
laser and is treated theoretically using the density matrix formalism. We use
realistic wurzite bandstructures taking valence-band mixing and strain-induced
piezo- electric fields into account. In addition, the many-body Coulomb
ineraction is treated in the screened time-dependent Hartree-Fock
approximation. We find that under typical experimental conditions, our
microscopic theory can be simplified and mapped onto a loaded string problem
which can be easily solved.Comment: 20 pages, 17 figure
Detecting the intermediate-mass Higgs boson through the associate production channel pp --> t + anti-t + H + X
We examine the detection of the intermediate-mass Higgs boson (IMH) at LHC
through the associate production channel pp-->t+(anti-t)+H+X-->l+photon+
photon+X'. It is shown that by applying kinematic cuts or b-tagging on the
final state jets, the main backgrounds of W(-->l+nu)+photon+photon+(n-jet) can
be reduced substantially without significant loss of signals. It is possible to
detect the Higgs boson at LHC through the pp-->t+(anti-t)+H+X channel using a
modest photon detector with mass resolution of about 3% of the photon pair
invariant mass.Comment: 10 pages, standard LaTex fil
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