Nuevos aportes al conocimiento del Paleozoico inferior del área de Salar del Rincón, Puna occidental, Argentina

Se presentan aquí nuevos hallazgos de graptolitos, trilobites y palinomorfos, tanto marinos como terrestres, realizados en el área de Salar del Rincón. Este análisis multidisciplinario constituye un nuevo aporte para el conocimiento del Paleozoico inferior de la Puna occidental. En el área han sido definidas dos unidades del Paleozoico inferior, la más antigua corresponde al complejo volcano-sedimentario de la Formación Las Vicuñas, constituido por areniscas silíceas y volcaniclásticas, lutitas y coquinas intercaladas con rocas volcánicas silíceas depositadas en un ambiente marino somero. En esta unidad se reconoció la presencia de dos especies de importancia en la correlación regional e intercontinental del límite Cambro-Ordovícico. Abundantes especímenes del trilobite Jujuyaspis keideli Kobayashi han sido identificados en coquinas, mientras que, rabdosomas multirramosos de graptolitos fueron coleccionados en lutitas negras y asignados aquí a Rhabdinopora flabelliformis parabola (Bulman), indicadora de una edad Tremadociana temprana. Por su parte, formas biseriadas conservadas en areniscas de grano fino a medio se han localizado por primera vez en el miembro superior de la Formación Salar del Rincón. Las mismas estarían indicando una edad ordovícica tardía a silúrica. Esta edad también es sugerida por la asociación de quitinozoos de la parte superior de este miembro, principalmente caracterizada por especies de Cyathochitina y Spinachitina de afinidades nordgondwánicas y laurénticas. Asimismo, el microfitoplancton marino (acritarcos y algas prasinofíceas) y las criptoesporas de origen terrestre, provenientes de niveles próximos al tope de la unidad, respaldan esta edad. En particular los acritarcos evidencian, como en otras regiones del mundo, un recambio durante el Hirnantiano, con la aparición de taxones típicamente silúricos que posteriormente se diversifican durante este último período. Este análisis brinda nuevos elementos de juicio para ajustar la edad de las unidades aflorantes en el área, confirmando que éstas representan un lapso temporal que involucra los límites Cambro-Ordovícico y, posiblemente, Ordovícico-Silúrico.Simposio I: 2º Simposio de bioestratigrafía y eventos del Paleozoico inferiorTrabajo subsidiado mediante los proyectos ANPCyT-PICT 1272 y CONICET-PIP 112-200801-01994.Facultad de Ciencias Naturales y Muse

Female-female competition is influenced by forehead patch expression in pied flycatcher females

There is increasing evidence that sexual selection operates in females and not only in males. However, the function of female signals in intrasexual competition has been little studied in species with conventional sex roles. In the Iberian populations of the pied flycatcher (Ficedula hypoleuca), some females express a white forehead patch, a trait that in other European populations, only males exhibit and has become a classical example in studies of sexual selection. Here, we investigated whether the expression of this trait plays a role in female-female competition during early breeding stages. To test this hypothesis, we simulated territorial intrusions by challenging resident females with stuffed female decoys expressing or not a forehead patch. We found that resident females directed more attacks per trial and maintained closer distances to non-patched decoys than to patched ones. Also, patched females were more likely to attack the decoy than non-patched females. Interestingly, females were more aggressive against the decoys when their mate was absent. This may indicate that females relax territory vigilance in the presence of their mate or that males interfere in the interaction between competing females. The behavior of resident males was also observed, although it was not affected by decoy's patch expression. Our findings suggest that the forehead patch plays a role in female intrasexual competition. If the forehead patch signals fighting ability, as it does in males, we may interpret that non-patched females probably avoided repeating costly agonistic encounters with the most dominant rivals.Fil: Morales, J.. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales; EspañaFil: Gordo, O.. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales; España. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Lobato, E.. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales; España. Cibio - Centro de Investigação Em Biodiversidade E Recursos Genéticos; PortugalFil: Ippi, Silvina Graciela. Universidad Nacional del Comahue. Centro Reg.universidad Bariloche. Departamento de Zoología. Cátedra de Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Martínez de la Puente, J.. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales; España. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Tomás, G.. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales; EspañaFil: Merino, S.. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales; EspañaFil: Moreno, J.. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales; Españ

Emission pattern of an aluminium nitride target for radio frequency magnetron sputtering

Thin amorphous aluminium nitride films, (a-AlN) have been produced by radio frequency magnetron sputtering at rf power 120W from a highly pure AlN target. The target is mounted below the substrate holder such that its position can be adjusted inside the vacuum chamber. The emission pattern is determined by means of thickness distribution of the deposited material obtained from optical transmission measurements. Holding a set of the process parameters constant and only varying the target-sample distance a three dimensional emission pattern of the AlN target was determined. The deposition rate and emission pattern for 120W and 180W (studied before) were compared. This comparison allows us to consider the target and shielding dimensions of our magnetron to predict the thickness and the sputtering rate distribution for any process parameter and sample target geometry

Effect of surface chemistry and associated protein corona on the long-term biodegradation of iron oxide nanoparticles in Vivo

The protein corona formed on the surface of a nanoparticle in a biological medium determines its behavior in vivo. Herein, iron oxide nanoparticles containing the same core and shell, but bearing two different surface coatings, either glucose or poly(ethylene glycol), were evaluated. The nanoparticles' protein adsorption, in vitro degradation, and in vivo biodistribution and biotransformation over four months were investigated. Although both types of nanoparticles bound similar amounts of proteins in vitro, the differences in the protein corona composition correlated to the nanoparticles biodistribution in vivo. Interestingly, in vitro degradation studies demonstrated faster degradation for nanoparticles functionalized with glucose, whereas the in vivo results were opposite with accelerated biodegradation and clearance of the nanoparticles functionalized with poly(ethylene glycol). Therefore, the variation in the degradation rate observed in vivo could be related not only to the molecules attached to the surface, but also with the associated protein corona, as the key role of the adsorbed proteins on the magnetic core degradation has been demonstrated in vitro

Structural and Electronic Properties of Small Neutral (MgO)n Clusters

Ab initio Perturbed Ion (PI) calculations are reported for neutral stoichiometric (MgO)n clusters (n<14). An extensive number of isomer structures was identified and studied. For the isomers of (MgO)n (n<8) clusters, a full geometrical relaxation was considered. Correlation corrections were included for all cluster sizes using the Coulomb-Hartree-Fock (CHF) model proposed by Clementi. The results obtained compare favorably to the experimental data and other previous theoretical studies. Inclusion of correlaiotn is crucial in order to achieve a good description of these systems. We find an important number of new isomers which allows us to interpret the experimental magic numbers without the assumption of structures based on (MgO)3 subunits. Finally, as an electronic property, the variations in the cluster ionization potential with the cluster size were studied and related to the structural isomer properties.Comment: 24 pages, LaTeX, 7 figures in GIF format. Accepted for publication in Phys. Rev.

Assessment of low-dose cisplatin as a model of nausea and emesis in beagle dogs, potential for repeated administration

Cisplatin is a highly emetogenic cancer chemotherapy agent, which is often used to induce nausea and emesis in animal models. The cytotoxic properties of cisplatin also cause adverse events that negatively impact on animal welfare preventing repeated administration of cisplatin. In this study, we assessed whether a low (subclinical) dose of cisplatin could be utilized as a model of nausea and emesis in the dog while decreasing the severity of adverse events to allow repeated administration. The emetic, nausea-like behavior and potential biomarker response to both the clinical dose (70 mg/m2) and low dose (15 mg/m2) of cisplatin was assessed. Plasma creatinine concentrations and granulocyte counts were used to assess adverse effects on the kidneys and bone marrow, respectively. Nausea-like behavior and emesis was induced by both doses of cisplatin, but the latency to onset was greater in the low-dose group. No significant change in plasma creatinine was detected for either dose groups. Granulocytes were significantly reduced compared with baseline (P = 0.000) following the clinical, but not the low-dose cisplatin group. Tolerability of repeated administration was assessed with 4 administrations of an 18 mg/m2 dose cisplatin. Plasma creatinine did not change significantly. Cumulative effects on the granulocytes occurred, they were significantly decreased (P = 0.03) from baseline at 3 weeks following cisplatin for the 4th administration only. Our results suggest that subclinical doses (15 and 18 mg/m2) of cisplatin induce nausea-like behavior and emesis but have reduced adverse effects compared with the clinical dose allowing for repeated administration in crossover studies

On the study of the transmission networks of blood parasites from SW Spain: diversity of avian haemosporidians in the biting midge Culicoides circumscriptus and wild birds

BACKGROUND: Blood-sucking flying insects play a key role in the transmission of pathogens of vector-borne diseases. However, at least for the case of avian malaria parasites, the vast majority of studies focus on the interaction between parasites and vertebrate hosts, but there is a lack of information regarding the interaction between the parasites and the insect vectors. Here, we identified the presence of malaria and malaria-like parasite lineages harbored by the potential vector Culicoides circumscriptus (Kieffer). Also, we identified some nodes of the transmission network connecting parasite lineages, potential insect vectors and avian hosts by comparing Haemoproteus and Plasmodium lineages isolated from insects with those infecting wild birds in this and previous studies. METHODS: Using a molecular approach, we analysed the presence of blood parasites in a total of 97 biting midges trapped in the Doñana National Park (SW Spain) and surrounding areas. Also, 123 blood samples from 11 bird species were analyzed for the presence of blood parasite infections. Blood parasites Haemoproteus and Plasmodium were identified by amplification of a 478 bp fragment of the mitochondrial cytochrome b gen. RESULTS: Thirteen biting midges harboured blood parasites including six Haemoproteus and two Plasmodium lineages, supporting the potential role of these insects on parasite transmission. Moreover, ten (8.1%) birds carried blood parasites. Seven Plasmodium and one Haemoproteus lineages were isolated from birds. Overall, six new Haemoproteus lineages were described in this study. Also, we identified the transmission networks of some blood parasites. Two Haemoproteus lineages, hCIRCUM03 and GAGLA03, were identical to those isolated from Corvus monedula in southern Spain and Garrulus glandarius in Bulgaria, respectively. Furthermore, the new Haemoproteus lineage hCIRCUM05 showed a 99% similarity with a lineage found infecting captive penguins in Japan. CONCLUSIONS: The comparison of the parasite lineages isolated in this study with those previously found infecting birds allowed us to identify some potential nodes in the transmission network of avian blood parasite lineages. These results highlight the complexity of the transmission networks of blood parasites in the wild that may involve a high diversity of susceptible birds and insect vectors

Massive Spin-2 States as the Origin of the Top Quark Forward-Backward Asymmetry

We show that the anomalously large top quark forward-backward asymmetry observed by CDF and D\O\, can naturally be accommodated in models with flavor-violating couplings of a new massive spin-2 state to quarks. Regardless of its origin, the lowest-order couplings of a spin-2 boson to fermions are analogous to the coupling of the graviton to energy/momentum, leading to strong sensitivity of the effects associated with its virtual exchange to the energy scales at hand. Precisely due to this fact, the observed dependence of the asymmetry on the $t\bar t$ invariant mass fits nicely into the proposed framework. In particular, we find a vast parameter space which can lead to the central value for the observed forward-backward asymmetry in the high mass bin, while being in accord with all of the existing experimental constraints.Comment: added discussion of differential observables at the LHC, matches version accepted for publication in JHE