228 research outputs found
Cosmological effects on the observed flux and fluence distributions of gamma-ray bursts
Several claims have been put forward that an essential fraction of
long-duration BATSE gamma-ray bursts should lie at redshifts larger than 5.
This point-of-view follows from the natural assumption that fainter objects
should, on average, lie at larger redshifts. However, redshifts larger than 5
are rare for bursts observed by Swift. The purpose of this article is to show
that the most distant bursts in general need not be the faintest ones. We
derive the cosmological relationships between the observed and emitted
quantities, and arrive at a prediction that is tested on the ensembles of
BATSE, Swift and Fermi bursts. This analysis is independent on the assumed
cosmology, on the observational biases, as well as on any gamma-ray burst
model. We arrive to the conclusion that apparently fainter bursts need not, in
general, lie at large redshifts. Such a behaviour is possible, when the
luminosities (or emitted energies) in a sample of bursts increase more than the
dimming of the observed values with redshift. In such a case dP(z)/dz > 0 can
hold, where P(z) is either the peak-flux or the fluence. This also means that
the hundreds of faint, long-duration BATSE bursts need not lie at high
redshifts, and that the observed redshift distribution of long Swift bursts
might actually represent the actual distribution.Comment: 2 pages, 1 figure; Death of Massive Stars: Supernovae and Gamma-Ray
Bursts, Proceedings IAU Symposium No. 27
Accurate Telescope Mount Positioning with MEMS Accelerometers
This paper describes the advantages and challenges of applying
microelectromechanical accelerometer systems (MEMS accelerometers) in order to
attain precise, accurate and stateless positioning of telescope mounts. This
provides a completely independent method from other forms of electronic,
optical, mechanical or magnetic feedback or real-time astrometry. Our goal is
to reach the sub-arcminute range which is well smaller than the field-of-view
of conventional imaging telescope systems. Here we present how this
sub-arcminute accuracy can be achieved with very cheap MEMS sensors and we also
detail how our procedures can be extended in order to attain even finer
measurements. In addition, our paper discusses how can a complete system design
be implemented in order to be a part of a telescope control system.Comment: Accepted for publication in PASP, 12 page
Soft Robotics : State of Art and Outlook
Widely used robot systems have a rigid base structure that limits the interaction with their environment. Due to the inflexible attachment points, conventional robotic structures can only manipulate objects with their special gripping system. It can be difficult for these systems to grasp objects with different shapes, handle complex surfaces or navigating in a heavily crowded environment. Many of the species observed in nature, like octopuses are able to perform complex sequences of movements using their soft-structured limbs, which are made up entirely of muscle and connective tissue. Researchers have been inspired to design and build robots based on these soft biological systems. Thanks to the soft structure and high degree of freedom, these soft robots can be used for tasks that would be extremely difficult to perform with traditional robot manipulators. This article discusses the capabilities and usability of soft robots, reviews the state of the art, and outlines the challenges in designing, modelling, manufacturing, and controlling
Soft robotics : state of art and outlook
Widely used robot systems have a rigid base structure that limits the interaction with their environment. Due to the inflexible attachment points, conventional robotic structures can only manipulate objects with their special gripping system. It can be difficult for these systems to grasp objects with different shapes, handle complex surfaces or navigating in a heavily crowded environment. Many of the species observed in nature, like octopuses are able to perform complex sequences of movements using their soft-structured limbs, which are made up entirely of muscle and connective tissue. Researchers have been inspired to design and build robots based on these soft biological systems. Thanks to the soft structure and high degree of freedom, these soft robots can be used for tasks that would be extremely difficult to perform with traditional robot manipulators. This article discusses the capabilities and usability of soft robots, reviews the state of the art, and outlines the challenges in designing, modelling, manufacturing, and controlling
Soft robotics : state of art and outlook
Widely used robot systems have a rigid base structure that limits the interaction with their environment. Due to the inflexible attachment points, conventional robotic structures can only manipulate objects with their special gripping system. It can be difficult for these systems to grasp objects with different shapes, handle complex surfaces or navigating in a heavily crowded environment. Many of the species observed in nature, like octopuses are able to perform complex sequences of movements using their soft-structured limbs, which are made up entirely of muscle and connective tissue. Researchers have been inspired to design and build robots based on these soft biological systems. Thanks to the soft structure and high degree of freedom, these soft robots can be used for tasks that would be extremely difficult to perform with traditional robot manipulators. This article discusses the capabilities and usability of soft robots, reviews the state of the art, and outlines the challenges in designing, modelling, manufacturing, and controlling
Soft Robotics: State of Art and Outlook
Widely used robot systems have a rigid base structure that limits the interaction with their environment. Due to the inflexible attachment points, conventional robotic structures can only manipulate objects with their special gripping system. It can be difficult for these systems to grasp objects with different shapes, handle complex surfaces or navigating in a heavily crowded environment. Many of the species observed in nature, like octopuses are able to perform complex sequences of movements using their soft-structured limbs, which are made up entirely of muscle and connective tissue. Researchers have been inspired to design and build robots based on these soft biological systems. Thanks to the soft structure and high degree of freedom, these soft robots can be used for tasks that would be extremely difficult to perform with traditional robot manipulators. This article discusses the capabilities and usability of soft robots, reviews the state of the art, and outlines the challenges in designing, modelling, manufacturing, and controlling
„Wir schaffen das, wenn...“ Anspielungen in Artikelüberschriften am Beispiel der deutschen Einwanderungsdebatte
Der vorliegende Beitrag berichtet über die Rolle von Anspielungen in Artikelüberschriften am Beispiel des deutschen Einwanderungsdiskurses. Im theoretischen Teil werden Anspielungen als ein Phänomen dargestellt, das nicht nur als bloße Manifestation von Intertextualität, sondern vielmehr als kreatives Mittel in einem interaktiven Prozess zwischen Autor/in und Leser/in fungiert. Im empirischen Teil wird anhand konkreter Beispiele eine Typologie erstellt, die Anspielungen nach dem Quellenbereich und nach Art der Bezugnahme auf den Prätext klassifiziert.
This paper examines the use of allusions in article headlines, using the example of the coverage of German immigration. In the theoretical section, allusions are presented as a phenomenon that functions not only as a manifestation of intertextuality, but rather as a creative instrument in an interactive process between the author and the reader. In the empirical section, a typology is created by means of concrete examples, which classifies allusions according to the source range and by way of references to the ‘urtext’. The analysis results are interpreted and conclusions are drawn.Tematem artykułu jest analiza roli aluzji w debacie dotyczącej imigracji, toczącej się na łamach niemieckich czasopism. W części teoretycznej zostanie przedstawione pojęcie aluzji nie tylko jako oczywiste odniesienie do innego tekstu, ale także jako środek służący zbudowaniu interakcji pomiędzy autorem a czytelnikiem. W części empirycznej, na podstawie konkretnych przykładów, stworzona zostanie typologia, która klasyfikuje aluzję według jej źródła oraz rodzaju odniesienia do tekstu pierwotnego
A Remarkable Angular Distribution of the Intermediate Subclass of Gamma‐Ray Bursts
We develop a method of testing the null hypothesis of intrinsic randomness in the angular distribution of gamma-ray bursts collected in the Current BATSE Catalog. The method is a modified version of the well-known counts-in-cells test and fully eliminates the nonuniform sky-exposure function of the BATSE instrument. Applying this method to the case of all gamma-ray bursts, we found no intrinsic nonrandomness. The test also did not find intrinsic nonrandomness for the short and long gamma-ray bursts. However, using the method on the new, intermediate subclass of gamma-ray bursts, the null hypothesis of intrinsic randomness for 181 intermediate gamma-ray bursts is rejected on the 96.4% confidence level. Taking 92 dimmer bursts from this subclass, we obtain a surprising result: this "dim" subclass of the intermediate subclass has an intrinsic nonrandomness on the 99.3% confidence level. On the other hand, the 89 "bright" gamma-ray bursts show no intrinsic nonrandomness
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