Trapped and excited w modes of stars with a phase transition and R>=5M

The trapped $w$-modes of stars with a first order phase transition (a density discontinuity) are computed and the excitation of some of the modes of these stars by a perturbing shell is investigated. Attention is restricted to odd parity (``axial'') $w$-modes. With $R$ the radius of the star, $M$ its mass, $R_{i}$ the radius of the inner core and $M_{i}$ the mass of such core, it is shown that stars with $R/M\geq 5$ can have several trapped $w$-modes, as long as $R_{i}/M_{i}<2.6$. Excitation of the least damped $w$-mode is confirmed for a few models. All of these stars can only exist however, for values of the ratio between the densities of the two phases, greater than $\sim 46$. We also show that stars with a phase transition and a given value of $R/M$ can have far more trapped modes than a homogeneous single density star with the same value of $R/M$, provided both $R/M$ and $R_{i}/M_{i}$ are smaller than 3. If the phase transition is very fast, most of the stars with trapped modes are unstable to radial oscillations. We compute the time of instability, and find it to be comparable to the damping of the $w$-mode excited in most cases where $w$-mode excitation is likely. If on the other hand the phase transition is slow, all the stars are stable to radial oscillations.Comment: To appear in Physical Review

Qualidade fisiológica das sementes do milho híbrido simples HS 200 em relação ao tamanho.

Para uniformizar e facilitar a semeadura, as sementes de milho são cultivadas quanto ao tamanho (espessura, comprimento e largura). A qualidade das sementes, principalmente as arredondadas e as de menor tamanho, tem sido questionada pelos agricultores e produtores de sementes. Com o objetivo de avaliar a qualidade fisiológicas das sementes do milho híbrido simples HS 200, foi realizado um trabalho na Embrapa Milho e Sorgo em Sete Lagoas, MG. Portanto, utilizaram-se sementes de três lotes oriundas de um mesmo campo de produção, as quais ficaram retidas na peneira 15 x 3/4 e também aquelas classificadas pela largura e comprimento (20c, 20L, 22L e 24). O delineamento experimental dos testes conduzidos no laboratório foi inteiramente casualizado e, daqueles conduzidos ao campo, foi em blocos ao acaso, foram realizados os testes de germinação, envelhecimento acelerado, frio modificado e emergência em campo. Pelos resultados, constata-se que as sementes longas de tamanho médio e de forma achatada (20L) apresentaram qualidade fisiológica superior, ao passo que as sementes de maior tamanho (24) e aquelas de forma arredondada retidas na peneira 15 x 3/4) apresentaram menor vigor. Foi verificada, ainda, que o teste de germinação foi o que mais se aproximou do estabelecimento da cultura e se mostrou confiável para produzir a emergência sob condição favorável de campo

Connection between dynamics and thermodynamics of liquids on the melting line

The dynamics of a large number of liquids and polymers exhibit scaling properties characteristic of a simple repulsive inverse power law (IPL) potential, most notably the superpositioning of relaxation data as a function of the variable TV{\gamma}, where T is temperature, V the specific volume, and {\gamma} a material constant. A related scaling law, TmVm{\Gamma}, with the same exponent {\Gamma}={\gamma}, links the melting temperature Tm and volume Vm of the model IPL liquid; liquid dynamics is then invariant at the melting point. Motivated by a similar invariance of dynamics experimentally observed at transitions of liquid crystals, we determine dynamic and melting point scaling exponents {\gamma} and {\Gamma} for a large number of non-associating liquids. Rigid, spherical molecules containing no polar bonds have {\Gamma}={\gamma}; consequently, the reduced relaxation time, viscosity and diffusion coefficient are each constant along the melting line. For other liquids {\gamma}>{\Gamma} always; i.e., the dynamics is more sensitive to volume than is the melting point, and for these liquids the dynamics at the melting point slows down with increasing Tm (that is, increasing pressure).Comment: 20 pages, 8 figures, 1 tabl

Side-Effects of Glyphosate to the Parasitoid Telenomus remus Nixon (Hymenoptera: Platygastridae).

Made available in DSpace on 2017-07-13T18:49:51Z (GMT). No. of bitstreams: 1 Steccaetal2016sideeffectsNE.pdf: 310045 bytes, checksum: 6f66c67e32aad75116d10d82e8ec95bc (MD5) Previous issue date: 2017-02-03201

Railway infrastructure asset management: the whole-system life cost analysis

Delivering the railway infrastructure whose functionality is sustainable and uncompromised in terms of safety and availability under ever decreasing budget constraints is a great challenge. The successful accomplishment of this task relies on the effective management of individual assets within a wider whole system perspective. This is a highly complex decision-making task where mathematical models are required to enable well-informed choices. In this study, a novel modelling framework is proposed for performing the whole system lifecycle cost analysis. The framework is based on two models: railway network performance and costs. Using the former model investigations of the effects of decisions can be carried out for the individual asset and the whole system. A Petri net modelling technique is used to construct the model. A form of Monte Carlo simulation is then used to obtain model results. The infrastructure performance model is then integrated with the cost model to perform the lifecycle cost analysis. A superstructure example is presented to demonstrate the application of the approach. The results show that taking into account interdependencies among the intervention activities greatly influences, not only the performance of the infrastructure, but also its lifecycle costs and thus should be included in the cost analysis

Radiation recoil from highly distorted black holes

We present results from numerical evolutions of single black holes distorted by axisymmetric, but equatorially asymmetric, gravitational (Brill) waves. Net radiated energies, apparent horizon embeddings, and recoil velocities are shown for a range of Brill wave parameters, including both even and odd parity distortions of Schwarzschild black holes. We find that a wave packet initially concentrated on the black hole throat, a likely model also for highly asymmetric stellar collapse and late stage binary mergers, can generate a maximum recoil velocity of about 150 (23) km/sec for even (odd) parity perturbations, significantly less than that required to eject black holes from galactic cores.Comment: 15 pages, 8 figure

Manejo fitotécnico da bananeira, cultivar D'Angola (AAB), visando ao controle da sigatoka-negra.

O trabalho teve como objetivo avaliar alternativas de manejo fitotécnico da bananeira comprida, cultivar D?Angola, visando ao controle da Sigatoka-negra. O experimento foi conduzido no campo experimental da Embrapa Acre no município de Rio Branco-AC com os tratamentos distribuídos em blocos ao acaso, completos, com seis repetições e constituídos por diferentes densidades de plantio, correspondendo: T1 - 3 m x 3 m (1.111 plantas/hectare); T2 - 3 m x 2 m (1.666 plantas/hectare); T3 - 2,5 m x 2 m (2.000 plantas/hectare); T4 - 4 m x 2 m x 1,5 m (1.333 plantas/hectare); T5 - 2 m x 2m (2.500 plantas/hectare) e; T6 - 3 m x 3 m (1.111 plantas/hectare), este último alocado sob o bosque de seringueira. Foram realizadas avaliações durante dois ciclos de produção. As plantas da cv. D'Angola (AAB) cultivadas no espaçamento 3,0 x 3,0m, sombreadas com seringueira, apresentaram maior altura de plantas, maior número de folhas vivas na floração e colheita, maior peso médio do cacho, maior massa das pencas, maior ciclo de produção e menor severidade da Sigatoka-negra. Maiores produtividades foram obtidas quando se adotaram maiores densidades de plantio. O consorciamento de bananeiras com árvores de seringueiras mostrou-se ser uma boa alternativa para viabilizar o cultivo da cv. D'Angola (banana comprida)

3-(2,4-Dibromo­anilino)-2,2-dimethyl-2,3-dihydro­naphtho[1,2-b]furan-4,5-dione: a new substituted aryl­amino nor-β-lapachone derivative

The title compound, C20H15Br2NO3, shows the furan ring to adopt a half-chair conformation and the two ring systems to be approximately perpendicular [dihedral angle = 71.0 (2)°]. In the crystal structure, inter­molecular C—H⋯O contacts link the mol­ecules