What sets the magnetic field strength and cycle period in solar-type stars?

Two fundamental properties of stellar magnetic fields have been determined by observations for solar-like stars with different Rossby numbers (Ro), namely, the magnetic field strength and the magnetic cycle period. The field strength exhibits two regimes: 1) for fast rotation it is independent of Ro, 2) for slow rotation it decays with Ro following a power law. For the magnetic cycle period two regimes of activity, the active and inactive branches, also have been identified. For both of them, the longer the rotation period, the longer the activity cycle. Using global dynamo simulations of solar like stars with Rossby numbers between ~0.4 and ~2, this paper explores the relevance of rotational shear layers in determining these observational properties. Our results, consistent with non-linear alpha^2-Omega dynamos, show that the total magnetic field strength is independent of the rotation period. Yet at surface levels, the origin of the magnetic field is determined by Ro. While for Ro<1 it is generated in the convection zone, for Ro>1 strong toroidal fields are generated at the tachocline and rapidly emerge towards the surface. In agreement with the observations, the magnetic cycle period increases with the rotational period. However, a bifurcation is observed for Ro~1, separating a regime where oscillatory dynamos operate mainly in the convection zone, from the regime where the tachocline has a predominant role. In the latter the cycles are believed to result from the periodic energy exchange between the dynamo and the magneto-shear instabilities developing in the tachocline and the radiative interior.Comment: 43 pages, 14 figures, accepted for publication in The Astrophysical Journa

Noether's Symmetry Theorem for Variational and Optimal Control Problems with Time Delay

We extend the DuBois-Reymond necessary optimality condition and Noether's symmetry theorem to the time delay variational setting. Both Lagrangian and Hamiltonian versions of Noether's theorem are proved, covering problems of the calculus of variations and optimal control with delays.Comment: This is a preprint of a paper whose final and definite form will appear in the international journal Numerical Algebra, Control and Optimization (NACO). Paper accepted for publication 15-March-201

Mathematical retroreflectors

Retroreflectors are optical devices that reverse the direction of incident beams of light. Here we present a collection of billiard type retroreflectors consisting of four objects; three of them are asymptotically perfect retroreflectors, and the fourth one is a retroreflector which is very close to perfect. Three objects of the collection have recently been discovered and published or submitted for publication. The fourth object - notched angle - is a new one; a proof of its retroreflectivity is given.Comment: 32 pages, 19 figure

Severe malaria: clinical case

We report a clinical case of severe malaria, where the rate of initial parasitaemia by Plasmodium falciparum was 43 %.Multiple organ dysfunction, including ARDS, forced admission in a close surveillance unit, with survival of the same.A brief review of the subject is made, focusing on severity and general conduct, alerting and awareness for this entity, whose expression, among us, could take on increasing importance. Resumo: Apresenta-se o caso clínico de um doente regressado de Angola com malária grave, em que o índice de parasitémia inicial pelo P. falciparum era de 43 %.Disfunção múltipla de orgãos, incluindo ARDS, implicaram o ingresso do doente numa unidade de alta vigilância, com sobrevivência do mesmo.Faz-se uma breve revisão do assunto, com enfoque nos indicadores de gravidade e na conduta geral, alertando e sensibilizando para esta entidade, cuja expressão, entre nós, poderá vir a assumir importância crescente. Keywords: Severe malaria, ARDS, Plasmodium falciparum, Parasitemia, Palavras-chave: Malária grave, SDRA, Plasmodium falciparum, Parasitemi

Numerical-experimental analysis of the permeability-porosity relationship in triply periodic minimal surfaces scaffolds

Bone Tissue Engineering has been focusing on improving the current methods for bone repair, being the use of scaffolds presented as an upgrade to traditional surgery techniques. Scaffolds are artificially porous matrices, meant to promote cell seeding and proliferation, being these properties influenced by the permeability of the structure. This work employed experimental pressure drop tests and Computational Fluid Dynamics models to assess permeability (and fluid streamlines) within different triply periodic minimal surfaces scaffold geometries (Schwarz D, Gyroid and Schwarz P). The pressure outputs from the computational analysis presented a good correlation with the experimental results, with R2 equal to 0.903; they have also shown that a lower porosity may not mean a lower permeability if the geometry is altered, such as the difference between 60% porous Gyroid scaffolds (8.1*10-9 mm2) and 70% porous Schwarz D scaffolds (7.1*10-9 mm2). Fluid streamlines revealed how the Gyroid geometries are the most appropriate design for most bone tissue engineering applications, due to their consistent fluid permeation, followed by Schwarz D. The Schwarz P geometries have shown flat streamlines and significant variation of the permeability with the porosity (an increase of 10% in their porosity lead to an increase in the permeability from 5.1*10-9 mm2 to 11.7*10-9 mm2), which would imply a poor environment for cell seeding and proliferation.info:eu-repo/semantics/publishedVersio

Deflection of ultra high energy cosmic rays by the galactic magnetic field: from the sources to the detector

We report the results of 3D simulations of the trajectories of ultra-high energy protons and Fe nuclei (with energies $E = 4 \times 10^{19}$ and $2.5 \times 10^{20} eV$) propagating through the galactic magnetic field from the sources to the detector. A uniform distribution of anti-particles is backtracked from the detector, at the Earth, to the halo of the Galaxy. We assume an axisymmetric, large scale spiral magnetic field permeating both the disc and the halo. A normal field component to the galactic plane ($B_z$) is also included in part of the simulations. We find that the presence of a large scale galactic magnetic field does not generally affect the arrival directions of the protons, although the inclusion of a $B_z$ component may cause significant deflection of the lower energy protons ($E = 4 \times 10^{19}$ eV). Error boxes larger than or equal to $\sim 5^{\circ}$ are most expected in this case. On the other hand, in the case of heavy nuclei, the arrival direction of the particles is strongly dependent on the coordinates of the particle source. The deflection may be high enough ($> 20^{\circ}$) as to make extremely difficult any identification of the sources unless the real magnetic field configuration is accurately determined. Moreover, not every incoming particle direction is allowed between a given source and the detector. This generates sky patches which are virtually unobservable from the Earth. In the particular case of the UHE events of Yakutsk, Fly's Eye, and Akeno, they come from locations for which the deflection caused by the assumed magnetic field is not significant.Comment: LaTeX + 2 postscript figures - Color versions of both figures (highly recommended) available via anonymous ftp at ftp://capc07.ast.cam.ac.uk/pub/uhecr_gmf as fig*.g

Parâmetros genéticos de caprinos da raça Saanen nascidos no Brasil de 1979 a 2009.

Resumo: A seleção permite que as características desejáveis sejam transmitidas para seus descendentes e que esses venham a produzir de forma eficiente, porém não existem trabalhos com dados oficiais no Brasil em que houvessem sido estimados os parâmetros genéticos das características biométricas e de tipo em caprinos. Foram avaliadas as características de 1243 caprinos da raça saanen, sendo 197 machos e 1046 fêmeas, nascidos de 1979 a 2009, com os seguintes parâmetros a serem estimados: perímetro torácico, comprimento corporal, altura na cernelha, altura, largura e comprimento da garupa, além das pontuações das principais características que definem o padrão racial e a aptidão do animal em uma escala de 0 a 100 pontos, incluindo a nota final e suas subdivisões, como característica racial, paleta e linha superior, membros e pés, tipo leiteiro, capacidade de corpo, úbere, ligamento traseiro e dianteiro, textura do úbere e tetos. Os componentes de variância foram estimados pelo método da Máxima Verossimilhança Restrita em análises multicaracterísticas incluindo todas as características simultaneamente. Foram encontrados valores de baixos a altos para as estimativas de herdabilidade das características morfofuncionais que variaram de 0,08 a 0,45 e correlações genéticas e fenotípicas de moderadas a altas, evidenciando a existência de variabilidade genética aditiva entre os animais e de possibilidade de resposta correlacionada. Genetic parameters of Saanen goats born in Brazil from 1979 to 2009. Abstract: The selection allows the desirable traits are transmitted to their offspring and that these will produce efficiently, but there are no jobs to official data in Brazil that had been estimated genetic parameters of biometric traits and type in goats. Were evaluated the traits of Saanen goats in 1243, being 197 males and 1046 females born from 1979 to 2009, with the following parameters to be estimated: heart girth, body length, wither height, height, width and length of rump addition to the scores of the main traits that define the breed standard and the suitability of the animal on a scale of 0 to 100 points, including the final score and its subdivisions, such as racial traits, shoulder and topline, limbs and feet, like dairy, capacity body, udder, linking front and rear, texture of the udder and teats. Variance components were estimated by Restricted Maximum Likelihood analyzes multicharacteristics including all features simultaneously. Values were found for low to high heritability estimates of morphological and functional traits that ranged from 0.08 to 0.45 and genetic and phenotypic correlations of moderate to high, showing the existence of additive genetic variability between animals and the possibility of response correlated

MHD Models of Axisymmetric Protostellar Jets

We present the results of a series of axisymmetric time-dependent magnetohydrodynamic (MHD) simulations of the propagation of cooling, overdense jets, motivated by the properties of outflows associated with young stellar objects. A variety of initial field strengths and configurations are explored for both steady and time-variable (pulsed) jets. Even apparently weak magnetic fields with strengths B < 60 micro-G in the pre-shocked jet beam can have a significant effect on the dynamics, for example by altering the density, width, and fragmentation of thin shells formed by cooling gas. A linear analysis predicts that axisymmetric pinch modes of the MHD Kelvin-Helmholtz instability should grow only slowly for the highly supermagnetosonic jets studied here; we find no evidence for them in our simulations. Some of our models appear unstable to current-driven pinch modes, however the resulting pressure and density variations induced in the jet beam are not large, making this mechanism an unlikely source of emission knots in the jet beam. In the case of pulsed jets, radial hoop stresses confine shocked jet material in the pulses to the axis, resulting in a higher density in the pulses in comparison to purely hydrodynamic models.Comment: 28 pages, 16 figures, accepted by Ap.

Aspectos epidemiológicos da caprinocultura cearense.

0 desenvolvimento da caprinocultura na regiao Nordeste do Brasil é severamente afetado por inúmeros fatores, entre eles a alta incidência de doenças. Objetivou-se conhecer o atual manejo sanitário empregado e os problemas sanitarios existentes na opiniao do criador do Ceara. 0 trabalho foi realizado nas varias regiôes criadoras de caprinos de raças leiteiras, nativas ou sem raça definida. Foram selecionadas 127 propriedades onde se aplicou um questionario. A percentagem média de mortalidade de animais foi de 22,8% e 4,6% em jovens e adultos, respectivamente. Os sinais clinicos relatados, por ordem, foram: anemia e edema de barbela (81,9% dos criatórios), diarréia (78,7%), aborto (75,6%), pododermatite (67,7%), linfadenite (66,9%), ectoparasitoses (63,8%), mamite (51,2%), pneumonia (44,9%), lesões vesiculares de pele (35,4%), ceratoconjuntivite (29,1%), problemas de ordem nervosa (26,8%), malformaçao fetal (15%), criptorquidismo (11%), prolapso de vagina/utero (11%) e artrite (8,7%). Pode-se concluir que o manejo sanitario dos caprinos desses criatórios é precario, independente do tipo de exploraçao ou regime de criaçao, a mortalidade de animais, principalmente de jovens, é considerada alta. Mesmo em criatórios com exploraçao leiteira não existe uma preocupaçao rigorosa com higiene e qualidade do leite. Epidemiological aspects of the raising goat in Ceará State, Brazil. ABSTRACT - The development of the goat raising in the Northeastern region of Brazil is hardly affected by several factors, among them, the high incidence of illness. The aim of this study was to assess the adopted sanitary management and the healthy problems according to Ceara?s goat breeders. The work was carried out in many regions of dairy and native goat raising. There were selected 127 properties where a questionnaire was applied. Mean percentage of animals? mortality was 22.8 and 4.6% for young and adult, respectively. Reported clinical signs were: anemia and dewlap edema (81.9% of the properties), diarrhea (78.7%), abortion (75.6%), foot rot (67.7%), lymphadenitis (66.9%), external parasites (63.8%), mastitis (51.2%), pneumonia (44.9%), goat pox (35.4%), keratoconjunctivitis (29.1%), nervous disorders (26.8%), fetal malformation (15%), cryptorchidism (11%), uterus/vagina prolapsed (11%), arthritis (8.7%), foot and mouth disease (2.4%) and rabies (0.8%). It could be concluded that the goats? sanitary management of those properties is precarious, independently either the exploitation way or the raising regimen; the animals? mortality, especially the youngest ones, is considered high; and even in dairy properties there is a lack of rigid worry concerning about hygiene and milk quality