Denjoy-Wolff points on the bidisk via models

Let $F=(\phi, \psi):\mathbb{D}^2\to\mathbb{D}^2$ denote a holomorphic self-map of the bidisk without interior fixed points. It is well-known that, unlike the case with self-maps of the disk, the sequence of iterates $$\{F^n:=F\circ F\circ \cdots \circ F\}$$ needn't converge. The cluster set of $\{F^n\}$ was described in a classical 1954 paper of Herv\'{e}. Motivated by Herv\'{e}'s work and the Hilbert space perspective of Agler, McCarthy and Young on boundary regularity, we propose a new approach to boundary points of Denjoy-Wolff type for the coordinate maps $\phi, \psi.$ We establish several equivalent descriptions of our Denjoy-Wolff points, some of which only involve checking specific directional derivatives and are particularly convenient for applications. Using these tools, we are able to refine Herv\'{e}'s theorem and show that, under the extra assumption of $\phi$ and $\psi$ possessing Denjoy-Wolff points with certain regularity properties, one can draw much stronger conclusions regarding the behavior of $\{F^n\}.

Mental representations of 12 year-old children about boiling and evaporation: A probabilistic association with convergent and divergent thinking

Students’ understanding of physical phenomena is determined by their relevant representations, which are very crucial for science education. Since these representations are often incompatible with the scientific view, their functional role in the learning processes has been the main interest of a plethora of research work over the last decades. In the present research students’ representations for boiling and evaporation are investigated and an attempt is made to correlate them with two cognitive variables, which have been shown to be involved in mental processes of learning science, namely convergent and divergent thinking. The study took place with the participation of 375 sixth-grade elementary school pupils (aged 11-12). Methodologically the ordinal logistic regression was implemented to correlate the categorical-type dependent variable with scale-type independent predictors. The results show that both convergent and divergent thinking are significantly associated with pupils' sufficient responses. Interpretation of the results and implications for science education are discussed

Properties and hormonal regulation of two structurally related cAMP phosphodiesterases from the rat Sertoli cell

Upon exposure to follicle-stimulating hormone (FSH), the gonadotropin-responsive Sertoli cell expresses increased rolipram-sensitive cAMP-specific phosphodiesterase (cAMP-PDE) activity. To understand the mechanisms leading to this activation, the cAMP-PDEs present in the Sertoli cell were characterized and their regulation studied. Comparison of the conceptual translates of two groups of PDE cDNA clones isolated from a Sertoli cell cDNA library (ratPDE3 and ratPDE4) showed that the encoded proteins were structurally similar, containing a core region of 455 amino acids with a sequence identity of 87%. The amino and carboxyl termini were divergent. Expression of these cDNAs in Escherichia coli and monkey COS-7 cells demonstrated that the encoded cAMP-PDEs had similar affinities for the cAMP substrate and were equally sensitive to a number of PDE inhibitors (rolipram greater than Ro 20-1724 greater than cilostamide). FSH stimulation of the Sertoli cell produced an increased rate of transcription of the ratPDE3 gene and elevated mRNA levels for ratPDE3 and to a lesser extent of ratPDE4. The increase in mRNA levels was detected after 1 h of stimulation. Forskolin, cholera toxin, and N6, O2'-dibutyryl cAMP produced a similar increase in rate of transcription and elevated mRNA levels, indicating that this activation is mediated by an increase in intracellular cAMP. RatPDE4 mRNA levels were maximal upon exposure to 10 ng of FSH/ml, whereas ratPDE3 mRNA levels could be further elevated, with higher FSH concentrations. The intensity of an immunoreactive band with characteristics identical to a purified cAMP-PDE, correlated with the increased cAMP hydrolytic activity after FSH or dibutyryl cAMP treatment, demonstrating that changes in cAMP-PDE protein levels are involved in this regulation. These data provide evidence that multiple cAMP-PDE forms are expressed in the rat Sertoli cell. Although differences in the pattern of activation of these forms were observed, these data show, that in the rat Sertoli cell, the cAMP-PDE activity is regulated by hormones via a novel mechanism that involves a cAMP-dependent activation of transcription of a PDE gene

Quantification and restoration of the pre‐drift extension across the NE Atlantic conjugate margins during the mid‐Permian‐early Cenozoic multi‐rifting phases

publishedVersio

Earth Impact Effects Program: A Web-based computer program for calculating the regional environmental consequences of a meteoroid impact on Earth

We have developed a Web-based program for quickly estimating the regional environmental consequences of a comet or asteroid impact on Earth(www.lpl.arizona.edu/ impacteffects). This paper details the observations, assumptions and equations upon which the program is based. It describes our approach to quantifying the principal impact processes that might affect the people, buildings, and landscape in the vicinity of an impact event and discusses the uncertainty in our predictions. The program requires six inputs: impactor diameter, impactor density, impact velocity before atmospheric entry, impact angle, the distance from the impact at which the environmental effects are to be calculated, and the target type (sedimentary rock, crystalline rock, or a water layer above rock). The program includes novel algorithms for estimating the fate of the impactor during atmospheric traverse, the thermal radiation emitted by the impact-generated vapor plume (fireball), and the intensity of seismic shaking. The program also approximates various dimensions of the impact crater and ejecta deposit, as well as estimating the severity of the air blast in both crater-forming and airburst impacts. We illustrate the utility of our program by examining the predicted environmental consequences across the United States of hypothetical impact scenarios occurring in Los Angeles. We find that the most wide-reaching environmental consequence is seismic shaking: both ejecta deposit thickness and air-blast pressure decay much more rapidly with distance than with seismic ground motion. Close to the impact site the most devastating effect is from thermal radiation; however, the curvature of the Earth implies that distant localities are shielded from direct thermal radiation because the fireball is below the horizon.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Implications of structural inheritance in oblique rift zones for basin compartmentalization: Nkhata Basin, Malawi Rift (EARS)

The Cenozoic East African Rift System (EARS) is an exceptional example of active continental extension, providing opportunities for furthering our understanding of hydrocarbon plays within rifts. It is divided into structurally distinct western and eastern branches. The western branch comprises deep rift basins separated by transfer zones, commonly localised onto pre-existing structures, offering good regional scale hydrocarbon traps. At a basin-scale, local discrete inherited structures might also play an important role on fault localisation and hydrocarbon distribution. Here, we consider the evolution of the Central basin of the Malawi Rift, in particular the influence of pre-existing structural fabrics.Integrating basin-scale multichannel 2D, and high resolution seismic datasets we constrain the border, Mlowe-Nkhata, fault system (MNF) to the west of the basin and smaller Mbamba fault (MF) to the east and document their evolution. Intra basin structures define a series of horsts, which initiated as convergent transfers, along the basin axis. The horsts are offset along a NE-SW striking transfer fault parallel to and along strike of the onshore Karoo (Permo-Triassic) Ruhuhu graben. Discrete pre-existing structures probably determined its location and, oriented obliquely to the extension orientation it accommodated predominantly strike-slip deformation, with more slowly accrued dip-slip.To the north of this transfer fault, the overall basin architecture is asymmetric, thickening to the west throughout; while to the south, an initially symmetric graben architecture became increasingly asymmetric in sediment distribution as strain localised onto the western MNF. The presence of the axial horst increasingly focussed sediment supply to the west. As the transfer fault increased its displacement, so this axial supply was interrupted, effectively starving the south-east while ponding sediments between the western horst margin and the transfer fault. This asymmetric bathymetry and partitioned sedimentation continues to the present-day, overprinting the early basin symmetry and configuration. Sediments deposited earlier become increasingly dissected and fault juxtapositions changed at a small (10-100 m) scale. The observed influence of basin-scale transfer faults on sediment dispersal and fault compartmentalization due to pre-existing structures oblique to the extension orientation is relevant to analogous exploration settings

Mid-sized complex crater formation in mixed crystalline-sedimentary targets: Insight from modeling and observation

Large impact crater formation is an important geologic process that is not fully understood. The current paradigm for impact crater formation is based on models and observations of impacts in homogeneous targets. Real targets are rarely uniform; for example, the majority of Earths surface is covered by sedimentary rocks and/or a water layer. The ubiquity of layering across solar system bodies makes it important to understand the effect target properties have on the cratering process. To advance understanding of the mechanics of crater collapse, and the effect of variations in target properties on crater formation, the first Bridging the Gap workshop recommended that geological observation and numerical modeling focussed on mid-sized (15-30 km diameter) craters on Earth. These are large enough to be complex; small enough to be mapped, surveyed and modelled at high resolution; and numerous enough for the effects of target properties to be potentially disentangled from the effects of other variables. In this paper, we compare observations and numerical models of three 18-26 km diameter craters formed in different target lithology: Ries, Germany; Haughton, Canada; and El'gygytgyn, Russia. Based on the first-order assumption that the impact energy was the same in all three impacts we performed numerical simulations of each crater to construct a simple quantitative model for mid-sized complex crater formation in a subaerial, mixed crystalline-sedimentary target. We compared our results with interpreted geological profiles of Ries and Haughton, based on detailed new and published geological mapping and published geophysical surveys. Our combined observational and numerical modeling work suggests that the major structural differences between each crater can be explained by the difference in thickness of the pre-impact sedimentary cover in each case. We conclude that the presence of an inner ring at Ries, and not at Haughton, is because basement rocks that are stronger than the overlying sediments are sufficiently close to the surface that they are uplifted and overturned during excavation and remain as an uplifted ring after modification and post-impact erosion. For constant impact energy, transient and final crater diameters increase with increasing sediment thickness.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Чувствительность детекторов ионизирующего излучения на основе наноструктурной керамики Al2O3

Работа выполнена при финансовой поддержке Минобрнауки РФ (договор №14.125.13.4696-МК – грант Президента РФ)