Parameter estimation of superdiffusive motion of energetic particles upstream of heliospheric shocks

In-situ spacecraft observations recently suggested that the transport of energetic particles accelerated at heliospheric shocks can be anomalous, i.e. the mean square displacement can grow non-linearly in time. In particular, a new analysis technique has permitted the study of particle transport properties from energetic particle time profiles upstream of interplanetary shocks. Indeed, the time/spatial power laws of the differential intensity upstream of several shocks are indicative of superdiffusion. A complete determination of the key parameters of superdiffusive transport comprises the power-law index, the superdiffusion coefficient, the related transition scale at which the energetic particle profiles turn to decay as power laws, and the energy spectral index of the shock accelerated particles. Assuming large-scale spatial homogeneity of the background plasma, the power-law behaviour can been derived from both a (microscopic) propagator formalism and a (macroscopic) fractional transport equation. We compare the two approaches and find a relation between the diffusion coefficients used in the two formalisms. Based on the assumption of superdiffusive transport, we quantitatively derive these parameters by studying energetic particle profiles observed by the Ulysses and Voyager 2 spacecraft upstream of shocks in the heliosphere, for which a superdiffusive particle transport has previously been observed. Further, we have jointly studied the electron energy spectra, comparing the values of the spectral indices observed with those predicted by the standard diffusive shock acceleration theory and by a model based on superdiffusive transport. For a number of interplanetary shocks and for the solar wind termination shock, for the first time we obtain the anomalous diffusion constants and the scale at which the probability of particle free paths changes to a power-law...Comment: 5 Figure

Vorschulische Förderung

Ziel der Untersuchung war es festzustellen, ob zwei unterschiedliche Förderansätze bei Kindern im letzten Vorschuljahr zu unterschiedlichen Entwicklungsfortschritten hinsichtlich verschiedener schulrelevanter Vorläuferfähigkeiten führen. Die Fähigkeiten der Kinder wurden im Herbst 2008 sowie im Frühjahr 2009 ermittelt. Die Stichprobe bestand aus 42 Kindern. 19 Kinder besuchten einen Kindergarten, 23 Kinder erhielten eine spezielle Förderung in einer 5+ Vorschulgruppe. Die Daten zur kognitiven Entwicklung wurden zu beiden Testzeitpunkten je nach Alter mit Teilen der Intelligenztestverfahren HAWIK-IV (Petermann & Petermann, 2007), HAWIVA-III (Ricken, Fritz, Schuck & Preuß, 2007) und WET (Kastner-Koller & Deimann, 2002) erhoben. Für die Ermittlung der Sprachentwicklung diente der SET-K 3-5 (Grimm, 2001), für die Erhebung der visumotorischen Kompetenzen wurden Teile des FEW-2 vorgegeben (Büttner, Dacheneder, Schneider & Weyer, 2008). Mit jedem Kind wurde außerdem ein Anamnesegespräch über Freundschaften, Rivalitäten, bevorzugte Aktivitäten und Interessen sowie über Ideen zum Schulalltag geführt. Beide Bildungseinrichtungen können dem Förderanspruch Genüge leisten und stehen nicht in direkter Konkurrenz zueinander. Die Eltern der Kinder scheinen intuitiv die für ihr Kind richtige Entscheidung getroffen zu haben, da sich die Kinder in der jeweiligen Umwelt gut entwickelten. Sind Kinder gut gefördert und begabt, was bei der Zielgruppe der 5+ angenommen wird, kann die Entscheidung für die eine oder andere Institution ohne Bedenken im Hinblick auf die Wünsche, Interessen und Bedürfnisse des Kindes getroffen werden, da beide Einrichtungen die Vorläuferfähigkeiten gut fördern.The purpose of this study was to examine the effect of two different kinds of preschool education on children's school readiness in connection with their intellectual abilities, language abilities and fine motor skills. The abilities were assessed at the beginning of the preschool education in fall 2008 and six months later, in spring 2009. The sample included 42 children from 67 to 74 month old, differentiated by the type of preschool education they were attending. 19 children went to a regular nursery school, 23 of them got a special treatment in a 5+ preschool class. Children's intellectual ability was determined using the Wechsler intelligence scale for children – IV, the Hannover Wechsler preschool and primary scale of intelligence – III and the Wiener Entwicklungstest. The language competence was assessed using the Sprachentwicklungstest für drei- bis fünfjährige Kinder and fine motor skills were determined using Frostigs Entwicklungstest der visuellen Wahrnehmung 2. The results indicate that the type of education – whether it is a nursery school or a special treatment in 5+ preschool classes – isn’t the most important factor. The parents probably already provided their children quality stimulation in the home environment that preschool activities did not surpass

The 5th edition of the Roma-BZCAT. A short presentation

The 5th edition of the Roma-BZCAT Multifrequency Catalogue of Blazars is available in a printed version and online at the ASDC website (http://www.asdc.asi.it/bzcat); it is also in the NED database. It presents several relevant changes with respect to the past editions which are briefly described in this paper.Comment: 5 pages, 3 figures. Accepted for publication in Astrophysics and Space Scienc

Superdiffusive Shock Acceleration

The theory of diffusive shock acceleration is extended to the case of superdiffusive transport, i.e., when the mean square deviation grows proportionally to t α, with α > 1. Superdiffusion can be described by a statistical process called Levy random walk, in which the propagator is not a Gaussian but it exhibits power-law tails. By using the propagator appropriate for Levy random walk, it is found that the indices of energy spectra of particles are harder than those obtained where a normal diffusion is envisaged, with the spectral index decreasing with the increase of α. A new scaling for the acceleration time is also found, allowing substantially shorter times than in the case of normal diffusion. Within this framework we can explain a number of observations of flat spectra in various astrophysical and heliospheric contexts, for instance, for the Crab Nebula and the termination shock of the solar wind

Ion Superdiffusion at the Solar Wind Termination Shock

We investigate the propagation of 0.54-3.5 MeV ions accelerated at the termination shock of the solar wind. Data are from Voyager 2 and refer to a time interval about one year long, just before the Voyager 2 termination shock crossing at the end of 2007 August, at roughly 83.7 AU. A recently developed technique, which allows to unravel the transport properties from an analysis of the energetic particle time profiles, is used. The ion time profiles exhibit a power-law decay from a few days to 200 days before the shock front, so that transport is found to be superdiffusive, with a mean square deviation growing like Δx 2 ∝ t α, with α ~ 1.3. This means that ion propagation in the heliosphere can be intermediate between normal diffusion and ballistic motion. The implication of ion superdiffusion on particle acceleration mechanisms at the termination shock is discussed, as well as some observational evidence coming from both Voyager 1 and Voyager 2, which questions diffusive shock acceleration

From Lévy walks to superdiffusive shock acceleration

In this paper, we present a general scenario for nondiffusive transport and we investigate the influence of anomalous, superdiffusive transport on Fermi acceleration processes at shocks. We explain why energetic particle superdiffusion can be described within the Levy walk framework, which is based on a power-law distribution of free path lengths and on a coupling between free path length and free path duration. A self-contained derivation of the particle mean square displacement, which grows as (Δx {sup 2}) = 2D {sub α} t {sup α} with α > 1, and the particle propagator, is presented for Levy walks, making use of a generalized version of the Montroll-Weiss equation. We also derive for the first time an explicit expression for the anomalous diffusion coefficient D {sub α} and we discuss how to obtain these quantities from energetic particle observations in space. The results are applied to the case of particle acceleration at an infinite planar shock front. Using the scaling properties of the Levy walk propagator, the energy spectral indices are found to have values smaller than the ones predicted by the diffusive shock acceleration theory. Furthermore, when applying the results to ions with energies of a few MeV accelerated atmore » the solar wind termination shock, the estimation of the anomalous diffusion coefficient associated with the superdiffusive motion gives acceleration times much smaller than the ones related to normal diffusion.« les

Morphological characterization of uterus and oviducts of Nelore bovine fetuses (Bos primigenius indicus) at various gestation stages

For the accomplishment of this research, twenty Nelore female fetuses in different phases of gestation were collected. The uterine horns and oviducts were dissected, measured and fragments were fixed in 4.00% tamponed paraformaldeid, processed and enclosed in paraplastic. The sections of 5mm were stained with hematoxilin and eosin, Masson's trichrome (to colagens fibers), Verhoeff (to elastic fibers) and with reticulin (to reticular fibers). The results showed that there is no significative difference among the right and left sides for the uterine horns and oviducts, but there is correlation among the measured organs in function of the age of the fetuses, or either, the growth of uterine horns and oviducts follow the fetal growth. The covering epithelium of the uterus does not present morphologic variations during the analyzed period. From 23 weeks of gestation, the mucous layer presents evolution in the development of the projections and there is no appearance of endometrial glands in the uterine wall in the analyzed period. The muscular layer presents only the developed internal circular sublayer up to 23 weeks of gestation and from 24 weeks of gestation there is presence of two sublayers. The serous layer is typical and it does not show variability in the gestation. The oviducts presents growth differences, mainly to the development of the folds that from 23 weeks of gestation they had become higher and ramified, however without appearance of tertiary folds. In the fetal development, the epithelium cilium becomes bigger. Up to 32 weeks of gestation, the muscular layer of oviducts presents the internal circular sublayer. The serous layer and mesosalpinge are typical and they do not present variations. The more characteristics variations occurred from 23 weeks of gestation.Para a realização desta pesquisa, foram coletados vinte fetos fêmeas em diferentes fases de gestação da raça Nelore. Os cornos uterinos e as tubas uterinas foram dissecados, mensurados e os fragmentos fixados em paraformaldeído tamponado a 4,00%, processados e incluídos em paraplástico. Os cortes com 5 mm foram corados com hematoxilina e eosina, tricrômio de Masson (para fibras colágenas), Verhoeff (para fibras elásticas) e com reticulina (para fibras reticulares). Os resultados mostraram que não há diferença significativa das mensurações entre os lados direito e esquerdo para os cornos uterinos e tubas uterinas, porém há correlação entre os valores obtidos das mensurações dos órgãos em função da idade dos fetos, ou seja, o crescimento dos órgãos acompanha o crescimento fetal. O epitélio de revestimento do útero não apresenta variações morfológicas evidentes no período analisado. A partir de 23 semanas de gestação, a mucosa uterina apresenta evolução marcante no desenvolvimento das projeções e não há aparecimento de glândulas endometriais na parede uterina no período analisado. A camada muscular apresenta a subcamada circular interna desenvolvida até 23 semanas de gestação e a partir de 24 semanas há presença das duas subcamadas. A camada serosa é típica e não mostra variabilidade no decorrer da gestação. As tubas uterinas apresentam diferenças de crescimento, principalmente dos pregueamentos que a partir de 23 semanas de gestação tornaram-se mais altos e ramificados, porém sem aparecimento de pregas terciárias. Com o desenvolvimento fetal, os cílios epiteliais do pregueamento tubárico são maiores em tamanho e em número. Até 32 semanas de gestação, a camada muscular das tubas uterinas apresenta apenas a subcamada circular interna. A camada serosa e o mesosalpinge são típicos e não apresentam variações importantes. As variações mais marcantes para os órgãos estudados ocorreram a partir de 23 semanas de gestação