Representing anisotropic subduction zones with isotropic velocity models: A characterization of the problem and some steps on a possible path forward

Despite the widely known fact that mantle flow in and around subduction zones produces the development of considerable seismic anisotropy, most P-wave tomography efforts still rely on the assumption of isotropy. In this study, we explore the potential effects of erroneous assumption on tomographic images and explore an alternative approach. We conduct a series of synthetic tomography tests based on a geodynamic simulation of subduction and rollback. The simulation results provide a self-consistent distribution of isotropic (thermal) anomalies and seismic anisotropy which we use to calculate synthetic delay times for a number of realistic and hypothetical event distributions. We find that anisotropy-induced artifacts are abundant and significant for teleseismic, local and mixed event distributions. The occurrence of artifacts is not reduced, and indeed can be exacerbated, by increasing richness in ray-path azimuths and incidence angles. The artifacts that we observe are, in all cases, important enough to significantly impact the interpretation of the images. We test an approach based on prescribing the anisotropy field as an a priori constraint and find that even coarse approximations to the true anisotropy field produce useful results. Using approximate anisotropy, fields can result in reduced RMS misfit to the travel time delays and reduced abundance and severity of imaging artifacts. We propose that the use of anisotropy fields derived from geodynamic modeling and constrained by seismic observables may constitute a viable alternative to isotropic tomography that does not require the inversion for anisotropy parameters in each node of the model

Estudio de laboratorio de la susceptibilidad a la corrosión intergranular del cinc y su relación con el contenido de aluminio

A method of test for determining the susceptibility of zinc to the intergranular corrosion was developped, considering that the action of water steam on zinc produces the mentioned type of corrosion. Local and foreing specimens have been studied. In the suscep- tibies specimens, the sign of intergranular corrosion, characterized by visual and micrographic observations, appears after 30 h exposition. Correlation between susceptibility and aluminium content was established: 0,005 $ of aluminium in laminated zinc was the maximum content in order to avoid corrosion.Se ideó un método de ensayo para, determinar la susceptibilidad del cinc a la corrosión intergranular, teniendo en cuenta que el ataque con vapor de agua provoca en el cinc ese tipo corrosión. Se ensayaron probetas de origen nacional y extranjero. En las muestras susceptibles,los signos, de corrosión intergranular — que fueron caracterizados mediante observaciones visuales y micrográficas -r aparecieron después de las 30, horas de exposición. Se estableció una correlación entre esa susceptibilidad y él contenido de aluminio, y se fijó como contenido máximo de aluminio en -cinc laminado el de 0,005 %

Symmetric Periodic Solutions of the Anisotropic Manev Problem

We consider the Manev Potential in an anisotropic space, i.e., such that the force acts differently in each direction. Using a generalization of the Poincare' continuation method we study the existence of periodic solutions for weak anisotropy. In particular we find that the symmetric periodic orbits of the Manev system are perturbed to periodic orbits in the anisotropic problem.Comment: Late

Diversity in Secondary Metabolites Including Mycotoxins from Strains of <i>Aspergillus </i>Section <i>Nigri </i>Isolated from Raw Cashew Nuts from Benin, West Africa

<p>In a previous study, raw cashew kernels were assayed for the fungal contamination focusin on strains belonging to the genus Aspergillus and on aflatoxins producers. These sample showed high contamination with Aspergillus section Nigri species and absence o aflatoxins. To investigate the diversity of secondary metabolites, including mycotoxins, th species of A. section Nigri may produce and thus threaten to contaminate the raw cashe kernels, 150 strains were isolated from cashew samples and assayed for their productio of secondary metabolites using liquid chromatography high resolution mass spectrometr (LC-HRMS). Seven species of black Aspergilli were isolated based on morphological an chemical identification: A.Tubingensis (44%), A. niger (32%), A. brasiliensis (10%), A. carbonariu (8.7%), A. luchuensis (2.7%), A. aculeatus (2%) and A. aculeatinus (0.7%). Fro these, 45 metabolites and their isomers were identified. Aurasperone and pyranonigrin A produced by all species excluding A. aculeatus and A. aculeatinus, were most prevalen and were encountered in 146 (97.3%) and 145 (95.7%) isolates, respectively. Three mycotoxin groups were detected: fumonisins (B2 and B4) (2.7%) ochratoxin A (13.3%), an secalonic acids (2%), indicating that these mycotoxins could occur in raw cashew nuts Thirty strains of black Aspergilli were randomly sampled for verification of species identit based on sequences of β-Tubulin and calmodulin genes. Among them, 27 isolates wer positive to the primers used and 11 were identified as A. niger, 7 as A.Tubingensis, 6 as A carbonarius, 2 as A. luchuensis and 1 as A. welwitschiae confirming the species names a based on morphology and chemical features. These strains clustered in 5 clades in A. sectio Nigri. Chemical profile clustering also showed also 5 groups confirming the speciespecific metabolites production.</p

Linear stability of the Lagrangian triangle solutions for quasihomogeneous potentials

In this paper we study the linear stability of the relative equilibria for homogeneous and quasihomogeneous potentials. Firstly, in the case the potential is a homogeneous function of degree $-a$, we find that any relative equilibrium of the $n$-body problem with $a>2$ is spectrally unstable. We also find a similar condition in the quasihomogeneous case. Then we consider the case of three bodies and we study the stability of the equilateral triangle relative equilibria. In the case of homogeneous potentials we recover the classical result obtained by Routh in a simpler way. In the case of quasihomogeneous potentials we find a generalization of Routh inequality and we show that, for certain values of the masses, the stability of the relative equilibria depends on the size of the configuration.Comment: 21 pages 4 figure

Does the spillage of petroleum products in Anopheles breeding sites have an impact on the pyrethroid resistance?

<p>Abstract</p> <p>Background</p> <p>The emergence of <it>Anopheles </it>populations capable of withstanding lethal doses of insecticides has weakened the efficacy of most insecticide based strategies of vector control and, has highlighted the need for further studies on the mechanisms of insecticide resistance and the various factors selecting resistant populations of mosquitoes. This research targeted the analysis of breeding sites and the oviposition behaviour of susceptible and resistant populations of <it>Anopheles </it>in localities of spilled petroleum products. The aim was to establish the possible contribution of oil spillage in the selection of pyrethroid resistance in malaria vectors.</p> <p>Methods</p> <p><it>Anopheles </it>breeding sites were identified and the insecticide susceptibility of the <it>Anopheles gambiae </it>populations mapped in 15 localities of South Western Nigeria. The presence of oil particles as well as the turbidity, the dissolved oxygen and the pH of each identified breeding site was recorded. Data were cross-analysed to correlate the habitat types and the insecticide susceptibility status of emerging mosquitoes. The second phase of this study was basically a laboratory model to provide more information on the implication of the spillage of petroleum on the selection of pyrethroid resistance in <it>An. gambiae</it>.</p> <p>Results</p> <p>Moderate levels of resistance following exposure to permethrin-impregnated papers were recorded with the majority of <it>An. gambiae </it>samples collected in the South Western Nigeria. Data from this study established a link between the constituency of the breeding sites and the resistance status of the emerging <it>Anopheles</it>.</p> <p>Conclusion</p> <p>This study has revealed the segregational occupation of breeding habitats by pyrethroid resistant and susceptible strains of <it>An. gambiae </it>in south-western Nigeria. Compiled results from field and laboratory research point out clear relationships between oil spillage and pyrethroid resistance in malaria vectors. The identification of this factor of resistance could serve as strong information in the management of insecticide resistance in some West African settings.</p

TIA-1 Cytotoxic Granule-Associated RNA Binding Protein Improves the Prognostic Performance of CD8 in Mismatch Repair-Proficient Colorectal Cancer

Evidence suggests a confounding effect of mismatch repair (MMR) status on immune response in colorectal cancer. The identification of innate and adaptive immune cells, that can complement the established prognostic effect of CD8 in MMR-proficient colorectal cancers patients, representing 85% of all cases, has not been performed