Lithium depletion in solar-like stars: effect of overshooting based on realistic multi-dimensional simulations

We study lithium depletion in low-mass and solar-like stars as a function of time, using a new diffusion coefficient describing extra-mixing taking place at the bottom of a convective envelope. This new form is motivated by multi-dimensional fully compressible, time implicit hydrodynamic simulations performed with the MUSIC code. Intermittent convective mixing at the convective boundary in a star can be modeled using extreme value theory, a statistical analysis frequently used for finance, meteorology, and environmental science. In this letter, we implement this statistical diffusion coefficient in a one-dimensional stellar evolution code, using parameters calibrated from multi-dimensional hydrodynamic simulations of a young low-mass star. We propose a new scenario that can explain observations of the surface abundance of lithium in the Sun and in clusters covering a wide range of ages, from $\sim$ 50 Myr to $\sim$ 4 Gyr. Because it relies on our physical model of convective penetration, this scenario has a limited number of assumptions. It can explain the observed trend between rotation and depletion, based on a single additional assumption, namely that rotation affects the mixing efficiency at the convective boundary. We suggest the existence of a threshold in stellar rotation rate above which rotation strongly prevents the vertical penetration of plumes and below which rotation has small effects. In addition to providing a possible explanation for the long standing problem of lithium depletion in pre-main sequence and main sequence stars, the strength of our scenario is that its basic assumptions can be tested by future hydrodynamic simulations.Comment: 7 pages, 3 figures, Accepted for publication in ApJ Letter

Parasitismo de larvas da mosca-do-mediterrâneo por Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) em diferentes cultivares de goiaba.

As moscas-das-frutas são as pragas que causam os maiores prejuízos à fruticultura mundial. Esses prejuízos podem ser diretos, com perdas na produção e indiretos. Por serem pragas quarentenárias, existem barreiras comerciais impostas pelos países importadores, limitando a exportação de frutos in natura. Apesar de o Brasil ser o terceiro maior produtor mundial de frutas, exporta-se apenas 2% dessa produção, enquanto que Diachasmimorpha longicaudata infestadas com larvas de Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Cinco lotes de oito frutos de goiaba, sendo dois frutos por cultivar, foram acondicionados em gaiolas contendo adultos de C. capitata, por 2h para oviposição. Após uma semana, quando as larvas já haviam se desenvolvido dentro dos frutos, estes foram expostos aos parasitóides durante 24h. Foram avaliados o peso médio dos frutos, a mortalidade das larvas, o número de pupários e as porcentagens de moscas e parasitóides emergidos

ORP3 splice variants and their expression in human tissues and hematopoietic cells

ORP3 is a member of the newly described family of oxysterol-binding protein (OSBP)-related proteins (ORPs). We previously demonstrated that this gene is highly expressed in CD34+ hematopoietic progenitor cells, and deduced that the &quot;full-length&quot; ORP3 gene comprises 23 exons and encodes a predicted protein of 887 amino acids with a C-terminal OSBP domain and an N-terminal pleckstrin homology domain. To further characterize the gene, we cloned ORP3 cDNA from PCR products and identified multiple splice variants. A total of eight isoforms were demonstrated with alternative splicing of exons 9, 12, and 15. Isoforms with an extension to exon 15 truncate the OSBP domain of the predicted protein sequence. In human tissues there was specific isoform distribution, with most tissues expressing varied levels of isoforms with the complete OSBP domain; while only whole brain, kidney, spleen, thymus, and thyroid expressed high levels of the isoforms associated with the truncated OSBP domain. Interestingly, the expression in cerebellum, heart, and liver of most isoforms was negligible. These data suggest that differential mRNA splicing may have resulted in functionally distinct forms of the ORP3 gene.<br /

Offspring in response to parental female densities in the fruit fly parasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae: Opiinae).

El presente trabajo forma parte de um programa de evaluación del parasitoide bracónido Diachasmimorpha longicaudata (Ashmead) como agente de biocontrol de Ceratitis capitata (Wiedemann) en Brasil

Light-to-light readout system of the CMS electromagnetic calorimeter

For the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) at CERN, an 80,000-crystal electromagnetic calorimeter will measure electron and photon energies with high precision over a dynamic range of roughly 16 bits. The readout electronics will be located directly behind the crystals, and must survive a total dose of up to 2×104 Gy along with 5×1013 n/cm 2. A readout chain consisting of a custom wide-range acquisition circuit, commercial ADC and custom optical link for each crystal is presently under construction. An overview of the design is presented, with emphasis on the large-scale fiber communication syste

The Dynamics of Radiative Shock Waves: Linear and Nonlinear Evolution

The stability properties of one-dimensional radiative shocks with a power-law cooling function of the form $\Lambda \propto \rho^2T^\alpha$ are the main subject of this work. The linear analysis originally presented by Chevalier & Imamura, is thoroughfully reviewed for several values of the cooling index $\alpha$ and higher overtone modes. Consistently with previous results, it is shown that the spectrum of the linear operator consists in a series of modes with increasing oscillation frequency. For each mode a critical value of the cooling index, $\alpha_\textrm{c}$, can be defined so that modes with $\alpha < \alpha_\textrm{c}$ are unstable, while modes with $\alpha > \alpha_\textrm{c}$ are stable. The perturbative analysis is complemented by several numerical simulations to follow the time-dependent evolution of the system for different values of $\alpha$. Particular attention is given to the comparison between numerical and analytical results (during the early phases of the evolution) and to the role played by different boundary conditions. It is shown that an appropriate treatment of the lower boundary yields results that closely follow the predicted linear behavior. During the nonlinear regime, the shock oscillations saturate at a finite amplitude and tend to a quasi-periodic cycle. The modes of oscillations during this phase do not necessarily coincide with those predicted by linear theory, but may be accounted for by mode-mode coupling.Comment: 33 pages, 12 figures, accepted for publication on the Astrophysical Journa

Controle biológico de moscas-das-frutas.

As moscas-das-frutas, insetos-praga que atacam diferentes variedades de frutas, são insetos da ordem Diptera e pertencem à família Tephritidae. Além dos danos diretos causados nas frutas com perdas grandes na produtividade, são, também, consideradas pragas de importância quarentenária, ou seja, existem restrições para exportação de frutos frescos para diferentes países