Silicate karst associated with lateritic formations (examples from eastern Niger)

Silicate and iron crust karst pits and sinkholes in eastern Niger are filled with reworked lateritic sediments or with unconsolidated palaeosoils and aeolian deposits. The fillings facies depend on the environmental conditions during deposition. Geomorphological and sedimentological studies on the karst fillings and the interpretation of various karst/filling associations allow an approach to the chronology of landscape development in eastern Niger plateaus

Hate speech

Hate speech - communication that attacks a person or a group on the basis of identity factors, such as gender, race, or religion - is one of the main digital threats to democracy. Hate speech has manifold, empirically evidenced consequences for targeted individuals and groups experiencing systematic discrimination and for social cohesion as a whole. Yet, while the upheaval of social media has put the concept in the spotlight, such attention has also structurally transformed its meaning, turning hate speech from a concept with clear defining properties into a family resemblance comprising all kinds of online abuse. This process is far from causing only academic issues. It also sidesteps historical oppression as a defining property and as the reason for which one is targeted by hate speech. Thus, the process has been belittling public animosity against historically oppressed groups, reducing hate speech merely to a matter of offensive language on social media. This chapter shows how and why this conceptual change has taken place and the consequences it unleashes. It specifically addresses the problems of concept stretching, concept shrinking, and the inflation of concepts. Finally, it concludes that such conceptual issues jeopardize the potential that digital media research on hate speech has to provide guidance to a broad range of social actors

Erste Untersuchungen von Hangrutschungen an der Frankenhöhe

Der vorliegende Beitrag faßt den derzeitigen Stand der Untersuchungen von Hangrutschungen im Bereich der Frankenhöhe, die im Rahmen des EPOCH-Programmes durchgeführt wurden, zusammen. Nach einer Inventarisierung der regionalen Rutschungsereignisse wird die Rutschung bei Obergailnau in einer geomorphologischen Detailkartierung vorgestellt. Für die Auslösung der Rutschung kommen mehrere Faktoren in Betracht: neben einer erhöhten Rutschungsanfälligkeit aufgrund der geologisch-tektonischen Verhältnisse muß v.a. auch eine Einflußnahme durch die Landnutzung mit berücksichtigt werden. Dazu zählen Steinbrucharbeiten in unmittelbarer Nähe der Rutschung, aber auch Wasserbaumaßnahmen am Schloßberg. In diesem potentielllabilisierten Gebiet kam es nach überdurchschnittlichen Niederschlägen Anfang 1958 zu einer Überschreitung der Belastungsgrenze des Hanges, die sich in einer großflächigen Rutschung äußerte. Die weiteren Untersuchungen sollen zeigen, ob sich die für Obergailnau herausgestellten Faktorenkomplexe im regionalen Rahmen verifizieren lassen.The paper summarizes the present status of investigations on landslides at a section of the Frankenhöhe escarpment of northem Bavaria, conducted within the context of an EPOCH program. Following an overview of landslide events in the region a recent landslide near the village of Obergailnau is presented in a detailed geomorphological map. Several factors may have contributed to triggering the landslide: an increased susceptibility to landsliding because of the geological and tectonical setting of the area may have been compounded with the landuse there, such as quarrying in the immediate vicinity and hydraulic engineering works at the Schloß mtn. upslope of the landslide area. Unusually high precipitation at the beginning of 1958 sufficiently lowered the load limit of this potentially unstable area, thus causing a major landslide. Further studies are planned in order to fmd out weiher Ihe complex of faclors identified at Obergailnau is of regional significance

Steady state shocks in accretion disks around a Kerr black hole

Results of numerical simulations of shock solutions in a geometrical thin accretion disk around a Kerr black hole (BH) are presented. Using the smoothed particle hydrodynamics (SPH) technique, the influence of the central object is included by means of an effective potential, We first present the theory of standing shock formation in accretion disks around a Kerr black hole, and show that the results of our numerical simulation agree very well with the theoretical results. We find that the shocks in an inviscid flow are very stable. We also remove the ambiguity prevalent regarding the location and stability of shocks in adiabatic flows. Finally we sketch some of the astrophysical consequences of our findings in relation to accretion disks in Active Galactic Nuclei (AGN) and Quasars.Comment: 9 pages (figures included) self-extracting compressed PostScript, in press (MNRAS

Ocorrência do fungo Colletotrichum gloeosporioides em mudas de bacurizeiro (Platonia insignis).

bitstream/item/131676/1/Comunicado-190-Ocorrencia-do-fungo-em-mudas-de-bacurizeiro.pd

Mass Outflows from Dissipative Shocks in Hot Accretion Flows

We consider stationary, axisymmetric hydrodynamic accretion flows in Kerr geometry. As a plausible means of efficiently separating a small population of nonthermal particles from the bulk accretion flows, we investigate the formation of standing dissipative shocks, i.e. shocks at which fraction of the energy, angular momentum and mass fluxes do not participate in the shock transition of the flow that accretes onto the compact object but are lost into collimated (jets) or uncollimated (winds) outflows. The mass loss fraction (at a shock front) is found to vary over a wide range (0 - 95%) depending on flow's angular momentum and energy. On the other hand, the associated energy loss fraction appears to be relatively low (<1%) for a flow onto a non-rotating black hole case, whereas the fraction could be an order of magnitude higher (<10%) for a flow onto a rapidly-rotating black hole. By estimating the escape velocity of the outflowing particles with a mass-accretion rate relevant for typical active galactic nuclei, we find that nearly 10% of the accreting mass could escape to form an outflow in a disk around a non-rotating black hole, while as much as 50% of the matter may contribute to outflows in a disk around a rapidly-rotating black hole. In the context of disk-jet paradigm, our model suggests that shock-driven outflows from accretion can occur in regions not too far from a central engine. Our results imply that a shock front under some conditions could serve as a plausible site where (nonthermal) seed particles of the outflows (jets/winds) are efficiently decoupled from bulk accretion.Comment: 25 pages, 10 black&white figures, Accepted to Ap

Da realidade a ser mediada à realidade midiática: status ontológico e epistemológico

Does there exist a world whose existence depends upon a perceiving subject? Can one recognize it? Under which conditions? To what extent? These questions are of central relevance to journalists, whose task it is to communicate reality. This article aims to develop a theoretical model of the ontological and epistemological status of both social reality, as an object of journalistic production, and the reality of the media, as a journalistic product. The basis for this model is provided by Karl Popper’s Three World conjecture and John Searle’s social ontology.¿Hay un mundo que independe de un sujeto conocedor para existir? Es posible conocerlo? ¿En qué condiciones? ¿Hasta dónde? Estas cuestiones desempeñan un papel central en la mediación de la realidad de la labor realizada por los periodistas. Este artículo tiene la intención de proporcionar un modelo para el análisis de la condición ontológica y epistemológica de la realidad social, de la materia prima de la labor periodística, y de la realidad de los medios como un producto periodístico. Para ello, buscamos fundamentación en la teoría de los mundos de Karl Popper y recogimos a John Searle para explicar la construcción de la realidad social.Há um mundo que independe de um sujeito conhecedor para existir? É possível conhecê-lo? Sob quais condições? Até que ponto? Estas questões assumem uma importância central no trabalho de mediação da realidade feito por jornalistas. O objetivo deste artigo é fornecer um modelo de análise dos status ontológico e epistemológico da realidade social, matéria-prima da produção jornalística, e da realidade midiática como produto jornalístico. Para isso, parte-se da teoria dos mundos de Karl Popper e da concepção sobre a construção da realidade social de John Searle

Resonance Oscillation Of Radiative Shock Waves In Accretion Disks Around Compact Objects

We extend our previous numerical simulation of accretion disks with shock waves when cooling effects are also included. We consider bremsstrahlung and other power law processes: $\Lambda \propto T^{\alpha} \rho^2$ to mimic cooling in our simulation. We employ {\it Smoothed Particle Hydrodynamics} technique as in the past. We observe that for a given angular momentum of the flow, the shock wave undergoes a steady, radial oscillation with the period is roughly equal to the cooling time. Oscillations seem to take place when the disk and cooling parameters (i.e., accretion rate, cooling process) are such that the infall time from shock is of the same order as the post-shock cooling time. The amplitude of oscillation could be up to ten percent of the distance of the shock wave from the black hole when the black hole is accreting. When the accretion is impossible due to the centrifugal barrier, the amplitude variation could be much larger. Due to the oscillation, the energy output from the disk is also seen to vary quasi-periodically. We believe that these oscillations might be responsible for the quasi periodic oscillation (QPO) behaviors seen in several black hole candidates, in neutron star systems as well as dwarf novae outbursts such as SS Cygni and VW Hyi.Comment: 24 pages of text plus 6 figures (in tar-compressed form); Astrophysical journal (in press

Stability of accretion disk around rotating black holes: a pseudo-general-relativistic fluid dynamical study

We discuss the solution of accretion disk when the black hole is chosen to be rotating. We study, how the fluid properties get affected for different rotation parameters of the black hole. We know that no cosmic object is static in Universe. Here the effect of the rotation of the black hole to the space-time is considered following an earlier work of the author, where the pseudo-Newtonian potential was prescribed for the Kerr geometry. We show that, with the inclusion of rotation of the black hole, the valid disk parameter region dramatically changes and disk becomes unstable. Also we discuss about the possibility of shock in accretion disk around rotating black holes. When the black hole is chosen to be rotating, the sonic locations of the accretion disk get shifted or disappear, making the disk unstable. To bring it in the stable situation, the angular momentum of the accreting matter has to be reduced/enhanced (for co/counter-rotating disk) by means of some physical process.Comment: 24 Latex pages including 7 figures; Accepted for publication in Astrophysical Journa

Als der Sommer zu Ende ging: Die Flüchtlingsdebatte im Wiener Wahlkampf auf Facebook

Dieser Artikel hat als Ziel, die Rolle der Flüchtlingskrise im Wiener Wahlkampf 2015 auf Facebook zu analysieren. Die Wahlen fanden auf dem Höhepunkt der Krise statt, als hunderttausende Schutzsuchende, hauptsächlich aus Syrien, die europäischen Grenzen überquerten. Die Situation verwandelte Österreich über Nacht in das wichtigste Transitland nach Westeuropa und rückte Wien in den Brennpunkt des Geschehens. Auf Basis des Agenda-Building-Ansatzes und des Begriffs von Problematisierung von Habermas wurden alle Posts auf den Facebook-Seiten der fünf Parteien des Wiener Gemeindesrates und ihrer SpitzenkandidatInnen während der letzten vier Wochen im Wahlkampf einer Inhaltsanalyse unterzogen (n = 935). Die Ergebnisse zeigen, dass die Interaktionen der NutzerInnen nicht auf die Thematisierung, sondern auf die Definition von Flüchtlingen als Problem zurückzuführen sind. Polarisierung und nicht Zustimmung führte dazu, dass das Flüchtlingsthema den Wahlkampf dominierte.This article aims to address the role of the refugee crisis in Vienna’s 2015 Mayoral Election campaign on Facebook. The election took place at the peak of the refugee crisis, when many thousands of people fleeing conflict regions, particularly Syria, crossed European borders in search for international protection. The situation transformed Austria into the most important transit country in Western Europe, with its capital Vienna becoming a key focal point. Based on the agenda-building approach and Habermas’ concept of problematization, all posts on the Facebook accounts of the five parties in the Viennese Parliament and their top candidates during the four weeks before election were submitted to a content analysis (n = 935). Outcomes show that the interaction of users determined the role of the refugees issue in the Vienna election campaign on Facebook. This interaction did not follow thematization, but rather the definition of refugees as a problem. Furthermore, the issue was able to dominate the election campaign not by gathering consensus against refugees, but by polarizing the debate between users