Analysis of pressure blips in aft-finocyl solid rocket motor

Ballistic anomalies have frequently occurred during the firing of several solid rocket motors (SRMs) (Inertial Upper Stage, Space Shuttle Redesigned SRM (RSRM) and Titan IV SRM Upgrade (SRMU)), producing even relevant and unexpected variations of the SRM pressure trace from its nominal profile. This paper has the purpose to provide a numerical analysis of the following possible causes of ballistic anomalies in SRMs: an inert object discharge, a slag ejection, and an unexpected increase in the propellant burning rate or in the combustion surface. The SRM configuration under investigation is an aft-finocyl SRM with a first-stage/small booster design. The numerical simulations are performed with a quasi-one-dimensional (Q1D) unsteady model of the SRM internal ballistics, properly tailored to model each possible cause of the ballistic anomalies. The results have shown that a classification based on the head-end pressure (HEP) signature, relating each other the HEP shape and the ballistic anomaly cause, can be made. For each cause of ballistic anomalies, a deepened discussion of the parameters driving the HEP signatures is provided, as well as qualitative and quantitative assessments of the resultant pressure signals

Elastic moduli approximation of higher symmetry for the acoustical properties of an anisotropic material

The issue of how to define and determine an optimal acoustical fit to a set of anisotropic elastic constants is addressed. The optimal moduli are defined as those which minimize the mean squared difference in the acoustical tensors between the given moduli and all possible moduli of a chosen higher material symmetry. The solution is shown to be identical to minimizing a Euclidean distance function, or equivalently, projecting the tensor of elastic stiffness onto the appropriate symmetry. This has implications for how to best select anisotropic constants to acoustically model complex materials.Comment: 20 page

Revealing the nature of magnetic shadows with numerical 3D-MHD simulations

We investigate the interaction of magneto-acoustic waves with magnetic network elements with the aim of finding possible signatures of the magnetic shadow phenomenon in the vicinity of network elements. We carried out three-dimensional numerical simulations of magneto-acoustic wave propagation in a model solar atmosphere that is threaded by a complexly structured magnetic field, resembling that of a typical magnetic network element and of internetwork regions. High-frequency waves of 10 mHz are excited at the bottom of the simulation domain. On their way through the upper convection zone and through the photosphere and the chromosphere they become perturbed, refracted, and converted into different mode types. We applied a standard Fourier analysis to produce oscillatory power-maps of the line-of-sight velocity. In the power maps of the upper photosphere and the lower chromosphere, we clearly see the magnetic shadow: a seam of suppressed power surrounding the magnetic network elements. We demonstrate that this shadow is linked to the mode conversion process and that power maps at these height levels show the signature of three different magneto-acoustic wave modes.Comment: Astronomy & Astrophysics Letters, in print 4 pages, 4 figure

Radiative transfer effects on Doppler measurements as sources of surface effects in sunspot seismology

We show that the use of Doppler shifts of Zeeman sensitive spectral lines to observe wavesn in sunspots is subject to measurement specific phase shifts arising from, (i) altered height range of spectral line formation and the propagating character of p mode waves in penumbrae, and (ii) Zeeman broadening and splitting. We also show that these phase shifts depend on wave frequencies, strengths and line of sight inclination of magnetic field, and the polarization state used for Doppler measurements. We discuss how these phase shifts could contribute to local helioseismic measurements of 'surface effects' in sunspot seismology.Comment: 12 pages, 4 figures, Accepted for publication in the Astrophysical Journal Letter

Ligulate inflorescence of Helianthus x multiflorus, cv. Soleild’Or, correlates with a mis-regulation of a CYCLOIDEA gene characterised by insertion of a transposable element

Members of CYCLOIDEA (CYC)/TEOSINTE BRANCHED1 (TB1) transcription factor family are essential to control flower symmetry and inflorescence architecture. In the Helianthus annuus genome, ten CYC/TB1 genes have been identified. Studies performed on mutants recognised HaCYC2c as one of the key players controlling zygomorphism in sunflower. We identified CYC2c genes in the diploid Helianthus decapetalus (HdCYC2c) and in the interspecific hybrid Helianthus × multiflorus (H × mCYC2cA and H × mCYC2cB), a triploid (2n = 3× = 51), originated from unreduced eggs of H. decapetalus fertilised by reduced H. annuus male gametes. Phylogenetic analysis showed that HdCYC2c and H × mCYC2c were placed within a CYC2 subclade together with HaCYC2c but distinct from it. The present data showed that in H. × multiflorus the allele derived from H. annuus is deleted or highly modified.\ud The H. × multiflorus taxon exists as radiate and ligulate inflorescence types. We analysed CYC2c expression in H. decapetalus and in the cultivar ‘Soleil d'Or’ of H. × multiflorus, a ligulate inflorescence type with actinomorphic corolla of disk flowers transformed into a zygomorphic ray‐like corolla. In H. decapetalus, the HdCYC2c gene showed differential expression between developing flower types, being up‐regulated in the corolla of ray flowers in comparison to the disk flower corolla. In H. × multiflorus, an insertion of 865 bp, which is part of a CACTA transposable element, was found in the 5′‐untranslated region (5′‐UTR) of H × mCYC2cB. This insertion could promote, even with epigenetic mechanisms, ectopic expression of the gene throughout the inflorescence, resulting in the observed loss of actinomorphy and originating a ligulate head

Fluxos, Encontros e Dispersões: Agenciamento Entre Arte e Clínica

Buscamos cartografar os fluxos artísticos que povoaram um CAPS para cuidados referentes ao uso de álcool e outras drogas de um município do Espírito Santo entre os anos de 2006 e 2016 e, com eles, delinear uma paisagem coletiva, relacionando-os com alguns momentos da arte e da clínica a partir do século XIX até os dias de hoje. Esta relação, por sua vez, visa apontar, ainda que de maneira circunscrita, a política de saúde mental que se fez tangenciando a arte ao longo dos anos, colocando em evidência as forças manicomiais que se fazem ainda presentes, assim como as resistências que são criadas para enfrentá-las. Evidencia alguns momentos de ampliação da clínica e seus agenciamentos com as artes moderna e contemporânea, com a construção e regulamentação das oficinas artísticas nos serviços de saúde mental, procurando tornar visíveis fluxos emergentes que apontam, por sua vez, para uma necessidade de desinstitucionalização da arte, assim como a territorialização de outros caminhos. Palavras chave: Arte - saúde mental. Álcool e outras drogas - CAPS

Numerical test of the Schoemberg-Muir theory

The Schoenberg-Muir theory states that an equivalent, homogeneous and anisotropic medium can be constructed from a layered medium composed of several thin layers, each anisotropic, under the assumption of stationarity. To test the theory we considered single transversely isotropic layers with different orientations of the symmetry axis and performed numerical simulations of wave propagation with a full-wave solver. The equivalent media have orthorhombic and monoclinic symmetries, respectively. The theory performed very well from the kinematical and dynamical points of view, even for strong anisotropy and layers described by media whose symmetry axes have different orientations.Fil: Carcione, José M.. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Picotti, Stefano. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Cavallini, Fabio. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Santos, Juan Enrique. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto del Gas y del Petróleo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Genome-wide analysis of LTR retrotransposon diversity and its impact on the evolution of the genus Helianthus (L.)

Background: Genome divergence by mobile elements activity and recombination is a continuous process that plays a key role in the evolution of species. Nevertheless, knowledge on retrotransposon-related variability among species belonging to the same genus is still limited. Considering the importance of the genus Helianthus, a model system for studying the ecological genetics of speciation and adaptation, we performed a comparative analysis of the repetitive genome fraction across ten species and one subspecies of sunflower, focusing on long terminal repeat retrotransposons at superfamily, lineage and sublineage levels. Results: After determining the relative genome size of each species, genomic DNA was isolated and subjected to Illumina sequencing. Then, different assembling and clustering approaches allowed exploring the repetitive component of all genomes. On average, repetitive DNA in Helianthus species represented more than 75% of the genome, being composed mostly by long terminal repeat retrotransposons. Also, the prevalence of Gypsy over Copia superfamily was observed and, among lineages, Chromovirus was by far the most represented. Although nearly all the same sublineages are present in all species, we found considerable variability in the abundance of diverse retrotransposon lineages and sublineages, especially between annual and perennial species. Conclusions: This large variability should indicate that different events of amplification or loss related to these elements occurred following species separation and should have been involved in species differentiation. Our data allowed us inferring on the extent of interspecific repetitive DNA variation related to LTR-RE abundance, investigating the relationship between changes of LTR-RE abundance and the evolution of the genus, and determining the degree of coevolution of different LTR-RE lineages or sublineages between and within species. Moreover, the data suggested that LTR-RE abundance in a species was affected by the annual or perennial habit of that species