Magnetic particles confined in a modulated channel: structural transitions tunable by tilting a magnetic field

The ground state of colloidal magnetic particles in a modulated channel are investigated as function of the tilt angle of an applied magnetic field. The particles are confined by a parabolic potential in the transversal direction while in the axial direction a periodic substrate potential is present. By using Monte Carlo (MC) simulations, we construct a phase diagram for the different crystal structures as a function of the magnetic field orientation, strength of the modulated potential and the commensurability factor of the system. Interestingly, we found first and second order phase transitions between different crystal structures, which can be manipulated by the orientation of the external magnetic field. A re-entrant behavior is found between two- and four-chain configurations, with continuous second order transitions. Novel configurations are found consisting of frozen in solitons. By changing the orientation and/or strength of the magnetic field and/or the strength and the spatial frequency of the periodic substrate potential, the system transits through different phases.Comment: Submitted to Phys. Rev. E (10 pages, 12 figures

Observations of OJ 287 from the Geodetic VLBI Archive of the Washington Correlator

We present 27 geodetic VLBI maps of OJ 287 obtained from the archive of the Washington correlator. The observations presented here were made between 1990 October and 1996 December. During this period a sequence of six superluminal components has been identified. We measured the proper motion of these components to be approximately 0.5 mas/yr, which is about twice as high as that seen in previous VLBI observations. These results imply a higher component ejection rate than previously observed, in good agreement with the observed occurrences of radio outbursts. We have examined a possible connection between VLBI components and optical flares in the framework of a binary black hole system.Comment: 9 pages, 5 included figures, emulateapj.sty, accepted to The Astrophysical Journa

Bases prácticas para el tratamiento del síndrome seborreico en el perro

El término seborrea o síndrome queratoseborreico describe un trastorno de la queratinización de carácter inespecífico que puede presentarse con origen primario o secundario, asociado, en este último caso, a muchas dermatosis del perro. El tratamiento sintomático de la seborrea es fundamental como apoyo al tratamiento específico y la única posibilidad terapéutica en los casos de seborrea primaria idiopática. Actualmente, el tratamiento antiseborreico se basa en productos de aplicación tópica y a menudo es difícil elegir entre la extensa gama de champús, lociones, cremas, etc., disponibles comercialmente. En la práctica, es importante conocer las características de sus principios activos y los efectos que tienen sobre la piel y trabajar con un número limitado de estos productos.The term seborrhea or keratoseborrheic syndrome describes a non-specific state of abnormal epidermal keratinization, that may arise with a primary or secondary origin, associated, in this latter case, with multiple canine dermatoses. Antiseborrheic therapy plays an importan: role in supporting specific treatment of the primary cause; moreover, it is the only possible treatment in those cases of idiopathic primary seborrhea. Currently, antiseborrheic therapy is based on topical formulations, but sometimes we are confused by the huge amount of shampoos, lotions, creams, ointments and others commercially available stuffs. Their proper use depends upon an understanding of their formulation and indications of their active components. From that point it is better to use a limited number of well known products

Observations of BL Lacertae from the Geodetic VLBI Archive of the Washington Correlator

We present maps of BL Lac obtained from geodetic VLBI data from the archive of the Washington correlator. The observations were made from 1996 March to 1996 November, with periods from one experiment to another as short as 1 month. The dominant structure of the maps is given by a superluminal component (C2) moving predominantly at position angle ~190°. At the later epochs a new superluminal component (C3) emerges from the core and moves along a trajectory at a higher position angle (200°). We also include maps from observations made in 1995 June and August showing the main component (C2) in the early stages of its evolution, as well as an older component (C1). The position angle of the component C1 is nearly the same as that of the new component C3. The component C2 shows indications of nonradial motion, which is discussed in terms of a helically distorted jet. The best fit was obtained for a half-opening angle of the jet of 2.6d and an angle of the helical axis to the line of sight of 17°

Observations of OJ 287 from the Geodetic-VLBI Archive of the Washington Correlator

We present 27 geodetic VLBI maps of OJ 287 obtained from the archive of the Washington correlator. The observations presented here were made between 1990 October and 1996 December. During this period a sequence of six superluminal components has been identified. We measured the proper motion of these components to be approximately 0.5 mas yr-1, which is about twice as high as that seen in previous VLBI observations. These results imply a higher component ejection rate than previously observed, in good agreement with the observed occurrences of radio outbursts. We have examined a possible connection between VLBI components and optical flares in the framework of a binary black hole system

Ciclos de vida comparados de Aedes aegypti (Diptera, Culicidae) do semiárido da Paraíba.

O presente trabalho teve como objetivo comparar os ciclos de vida entre amostras de populações de Aedes aegypti (Linnaeus, 1762) coletadas em dez municípios localizados no semiárido paraibano. Os ciclos de vida foram estudados a uma temperatura de 26 ± 2ºC, umidade relativa de 60 ± 10% e fotofase de 12 horas. Diariamente foram avaliados os períodos de desenvolvimentos e as viabilidades das fases de ovo, larva e pupa, bem como a razão sexual, longevidade, tamanho e fecundidade dos adultos. Foi realizada uma análise de agrupamento, utilizando-se uma matriz de distância euclidiana através do método da média não-ponderada. As durações e viabilidades para as fases de ovo, larva e pupa apresentaram respectivamente, uma variação média de 3,7 a 4,7 dias e 82,8% a 97,7%, 9,1 a 10,8 dias e 91,2% a 99,2% e de 2,1 a 2,5 dias e 93,5% a 98,4%. O comprimento alar foi de 5,13 a 5,34 mm para as fêmeas e de 4,18 a 4,25 mm para os machos. A menor fecundidade (153,6 ovos/fêmea) ocorreu na população de A. aegypti oriunda de Pedra Lavrada, enquanto que a maior fecundidade (310,6 ovos/fêmea) foi constatada para A. aegypti de Campina Grande. A análise de agrupamento com base na similaridade dos dados biológicos revelou a formação de dois grandes grupos distintos, onde as populações de A. aegypti de Serra Branca e Cuité apresentam maior similaridade entre si. As diferenças de ciclos biológicos verificadas entre as populações de A. aegypti demonstra a capacidade dessa espécie de sofrer variações na sua biologia e se adaptar às diferentes condições ambientais, favorecendo a permanência deste inseto nessas áreas com aumento do risco de transmissão do vírus da dengue

Alterações na cor, vitamina C, fenólicos e atividade de enzimas oxidativas durante o desenvolvimento de manga Tommy Atkins.

Este estudo teve como objetivo caracterizar as mudanças na cor da polpa, conteúdo de clorofila, carotenôides, vitamina C e fenólicos, bem como determinar a atividade da cultivar oxidado durante o desenvolvimento do fruto da mangueira cv. Tommy Atkins, da antese até a colheita comercial, considerando a definição do ponto de colheita ideal