Simple tools to study global dynamics in non-axisymmetric galactic potentials - I

In a first part we discuss the well-known problem of the motion of a star in a general non-axisymmetric 2D galactic potential by means of a very simple but almost universal system: the pendulum model. It is shown that both loop and box families of orbits arise as a natural consequence of the dynamics of the pendulum. An approximate invariant of motion is derived. A critical value of the latter sharply separates the domains of loops and boxes and a very simple computation allows to get a clear picture of the distribution of orbits on a given energy surface. Besides, a geometrical representation of the global phase space using the natural surface of section for the problem, the 2D sphere, is presented. This provides a better visualization of the dynamics. In a second part we introduce a new indicator of the basic dynamics, the Mean Exponential Growth factor of Nearby Orbits (MEGNO), that is suitable to investigate the phase space structure associated to a general Hamiltonian. When applied to the 2D logarithmic potential it is shown to be effective to obtain a picture of the global dynamics and, also, to derive good estimates of the largest Lyapunov characteristic number in realistic physical times. Comparisons with other techniques reveal that the MEGNO provides more information about the dynamics in the phase space than other wide used tools. Finally, we discuss the structure of the phase space associated to the 2D logarithmic potential for several values of the semiaxis ratio and energy. We focus our attention on the stability analysis of the principal periodic orbits and on the chaotic component. We obtain critical energy values for which connections between the main stochastic zones take place. In any case, the whole chaotic domain appears to be always confined to narrow filaments, with a Lyapunov time about three characteristic periods.Facultad de Ciencias Astronómicas y Geofísica

Global dynamics and diffusion in the rational standard map

In this paper we study the dynamics of the Rational Standard Map, which is a generalization of theStandard Map. It depends on two parameters, the usual K and a new one, 0 ≤ μ < 1, that breaksthe entire character of the perturbing function. By means of analytical and numerical methods it isshown that this system presents significant differences with respect to the classical Standard Map. Inparticular, for relatively large values of K the integer and semi-integer resonances are stable for somerange of μ values. Moreover, for K not small and near suitable values of μ , its dynamics could beassumed to be well represented by a nearly integrable system. On the other hand, periodic solutionsor accelerator modes also show differences between this map and the standard one. For instance,in case of K ≈ 2 π accelerator modes exist for μ less than some critical value but also within verynarrow intervals when 0 . 9 < μ < 1. Big differences for the domains of existence of rotationallyinvariant curves (much larger, for μ moderate, or much smaller, for μ close to 1 than for the standardmap) appear. While anomalies in the diffusion are observed, for large values of the parameters, thesystem becomes close to an ergodic one.Fil: Cincotta, Pablo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Simó, Carles. Universidad de Barcelona; Españ

Regulación jurídica y ámbitos aplicados a la criminología fórense. Del modelo anglosajón al español

La Criminología Forense (CF) es la rama aplicada de la Ciencia Criminológica basada en la recolección, análisis y presentación de datos científicos estructurada en forma de informe pericial, susceptible de ser utilizado en el entorno judicial con la finalidad de servir como Ciencia auxiliar al sistema judicial. Con el objetivo de proponer unas bases para su utilización en España, se realiza una revisión literaria sobre la regulación de la pericia forense en Ciencias Sociales y las funciones de la CF en dicho contexto. Para ello se identifican las bases para la admisión de la CF en el ámbito penal anglosajón y en el marco legislativo español, abordándose sus funciones y objetos más frecuente. Por último, se comparan las legislaciones analizadas y se analiza su posible aplicación en nuestro país

The Invasive Spider Badumna longinqua (L. Koch, 1867) (Araneae: Desidae) in Argentina: New Distributional Records, with Notes on its Expansion and Establishment

Badumna longinqua (L. Koch 1867) is a medium-sized spider native from Australia. Due to its synanthropic habitat, this spider expanded their range distribution, reaching Germany, Japan, New Zealand, Uruguay and USA. We found specimens of this species in different localities from Buenos Aires Province, Argentina. Therefore, we report the first records of B. longinqua to Argentina, and discuss aspects of its distribution.Fil: Pompozzi, Gabriel Alejandro. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados Ii; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Peralta, Luciano. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Artrópodos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Simó, Miguel. Universidad de la República. Facultad de Ciencias; Urugua

Primer registro de Oxidus gracilis (C.L. Koch, 1847), con notas sobre su historia natural y distribución (Polydesmida: Paradoxosomatidae)

The millipede species Oxidus gracilis (Polydesmida:Paradoxosomatidae) is recorded for the first time in Uruguay. This constitutes the first record of the Order Polydesmida and the family Paradoxosomatidae for the country. The species was found in synantropic environments. Data on its natural history and distribution in the country are included.Se registra por primera vez para Uruguay la especie de milpiés Oxidus gracilis (Polydesmida: Paradoxosomatidae). Este constituye el primer registro del Orden Polydesmida y de la familia Paradoxosomatidae para el país. La especie fue encontrada en ambientes sinantrópicos. Se incluyen datos sobre su historia natural y de distribución en el país

Capillary electrophoresis-mass spectrometry of Spirulina platensis proteins obtained by pressurized liquid extraction

In this work, the usefulness of CE-MS to monitor and optimize the pressurized liquid extraction (PLE) of proteins from Spirulina platensis microalga is demonstrated. Crude and purified PLE extracts from microalga were analyzed by CE-MS. It was observed that the use of purification protocols of phycobiliproteins (namely, ultrafiltration or precipitation- dialysis-freeze drying) resulted in better CE resolution and MS signals, demonstrating that sample matrix plays an important role in CE-MS of proteins in real samples. Ultrafiltration was found less laborious and much faster than precipitationdialysis- freeze drying (1 vs. 48 h). Direct analysis of crude extracts was demonstrated to be also possible by CE-MS, providing less-quality information but enough to characterize PLE extracts in a much faster way. Therefore, the latter protocol was selected to monitor and optimize the extraction process of phycobiliproteins from S. platensis. To do that, different extraction conditions were tested, including time, temperature and pressure of extraction, nature of pressurized liquid, distribution of microalga inside the extraction cell, type of packing, etc. It is demonstrated that the combined use of PLE and CE-MS allows the attainment of extracts rich in phycobiliproteins in short extraction times (namely, yields of 20% can be obtained in less than 2 h under the optimum PLE process in an automatic way). To our knowledge, this work shows for the first time the usefulness of CE-MS for monitoring and optimizing a PLE process.Financial support from AGL2002–04621-C02–02 project (CICYT, Ministerio de Ciencia y Tecnlogía) is acknowledged. M.H. thanks MCYT for an FPI grant. C.S. thanks Consejería de Educación y Cultura (Comunidad de Madrid) for a fellowship.Peer reviewe

From the Hénon conservative map to the Chirikov standard map for large parameter values

In this paper we consider conservative quadratic Hénon maps and Chirikov's standard map, and relate them in some sense. First, we present a study of some dynamical properties of orientation-preserving and orientation-reversing quadratic Hénon maps concerning the stability region, the size of the chaotic zones, its evolution with respect to parameters and the splitting of the separatrices of fixed and periodic points plus its role in the preceding aspects. Then the phase space of the standard map, for large values of the parameter $k$, is studied. There are some stable orbits which appear periodically in $k$ and are scaled somehow. Using this scaling, we show that the dynamics around these stable orbits is one of the above Hénon maps plus some small error, which tends to vanish as $k \rightarrow \infty$. Elementary considerations about diffusion properties of the standard map are also presented

Effect of Islands in Diffusive Properties of the Standard Map for Large Parameter Values

In this paper we review, based on massive, long-term, numerical simulations, the effect of islands on the statistical properties of the standard map for large parameter values. Different sources of discrepancy with respect to typical diffusion are identified, and their individual roles are compared and explained in terms of available limit models