Analysis of OSO data to determine the structure and energy balance of the solar chromosphere

A detailed reexamination of the temperature-density structure of the photosphere and low chromosphere shows that the middle and upper chromosphere, which directly emits most of the OSO spectrum, is sensitive to conditions in this underlying region of the atmosphere. A model of this region is based on a unified compilation of all recently published broadband flux and central intensity observations of the solar spectrum from 500 microns in the far infrared to 1220 A in the far ultraviolet. This extensive compilation includes the OSO 4 and 6 observations in the wavelength range 1400 to 1220 A. A model is presented of the quiet solar atmosphere in the height range between the temperature minimum and the upper part of the chromosphere-corona transition region. This model is based on statistical equilibrium calculations of H, He 1, He 2, Si 1, C 1, and other ions

Adaptive User Perspective Rendering for Handheld Augmented Reality

Handheld Augmented Reality commonly implements some variant of magic lens rendering, which turns only a fraction of the user's real environment into AR while the rest of the environment remains unaffected. Since handheld AR devices are commonly equipped with video see-through capabilities, AR magic lens applications often suffer from spatial distortions, because the AR environment is presented from the perspective of the camera of the mobile device. Recent approaches counteract this distortion based on estimations of the user's head position, rendering the scene from the user's perspective. To this end, approaches usually apply face-tracking algorithms on the front camera of the mobile device. However, this demands high computational resources and therefore commonly affects the performance of the application beyond the already high computational load of AR applications. In this paper, we present a method to reduce the computational demands for user perspective rendering by applying lightweight optical flow tracking and an estimation of the user's motion before head tracking is started. We demonstrate the suitability of our approach for computationally limited mobile devices and we compare it to device perspective rendering, to head tracked user perspective rendering, as well as to fixed point of view user perspective rendering

Die Aufgaben der Encyclopaedia Cinematographica im Spiegel ihres 40jährigen Bestehens : Arbeitsunterlage für die Redaktionsausschußtagung der Encyclopaedia Cinematographica, Göttingen, 5. - 9.10.1992

Arbeitsungsunterlage für die Redaktionsausschußtagung der ENCYCLOPAEDIA CINEMATOGRAPHICA. Göttingen, 5.-9.10.1992. H. Kalkofen, Inst. Wiss. Film. Während die ENCYCLOPAEDIA CINEMATOGRAPHICA nicht verbirgt, daß sie nun 40 Jahre alt geworden ist, kann sie auf die doch nicht ganz unziemliche Frage, wer sie denn überhaupt sei, keine einhellige Antwort geben. Es wird gezeigt, daß die EC im Lauf der Zeit ihres Bestehens verschiedene Selbst-Konzeptionen bekundet hat, die miteinander zum Teil vereinbart werden können, zum Teil aber nicht. Der prinzipielle Gegensatz zwischen dem sich, modelltheoretisch gesehen, durchaus nicht zu Unrecht als "Bewequnqspräparat" begreifenden Kinematogramm und dem die pure Deskription überschreitenden Film, dem es um die Vermittlung von Sinnzusammenhänqen geht, ließ sich nur in den Jahren der Gründungszeit bemanteln und verkennen. Es wird entschieden dafür plädiert, daß sich die ENCYCLOPAEDIA CINEMATOGRAPHICA auf ihre kinematographische Natur zurückbesinnt und sie weiterentwickelt. Andererseits scheint die Gründung eines internationalen Archivs wissenschaftlicher Filme aus mehreren Gründen erforderlich. Dieses Archiv, bei dessen Namensgebung auf das Epitheton /kinematographisch/ der K1arheit halber zu verzichten wäre, und die ENCYCLOPAEDIA CINEMATOGRAPHICA könnten sich, wiewohl eindeutig getrennt, gemeinsamer Infrastrukturen bedienen.Whereas the EC does not conceal that it has turned forty, it can give no clear answer to the not improper question of what it might happen to be. It shall be demonstrated that the EC has promulgated various self-concepts in the course of its existence, some of which are consistent with one another, while others are not. The fundamental discrepancy between the cinematogramme, which is -from a model-theoretical point of view -not wrongly understood to be a "movement specimen", and films transcending the boundaries of pure description, which are concerned to convey contexts of meaning, could still be concealed and misapprehended in the early years after the founding. This is decidedly a plea that the EC should recollect its cinematographic nature, and develop it further. On the other hand, the founding of an international archive of scientific films seems necessary for several reasons. This archive, the naming of which should, in the interest of clarity, eschew the epithet "cinematoqraphic", and the EC could, though wholly separate, make use of a common infrastructure

Small-scale structure and dynamics of the lower solar atmosphere

The chromosphere of the quiet Sun is a highly intermittent and dynamic phenomenon. Three-dimensional radiation (magneto-)hydrodynamic simulations exhibit a mesh-like pattern of hot shock fronts and cool expanding post-shock regions in the sub-canopy part of the inter-network. This domain might be called "fluctosphere". The pattern is produced by propagating shock waves, which are excited at the top of the convection zone and in the photospheric overshoot layer. New high-resolution observations reveal a ubiquitous small-scale pattern of bright structures and dark regions in-between. Although it qualitatively resembles the picture seen in models, more observations - e.g. with the future ALMA - are needed for thorough comparisons with present and future models. Quantitative comparisons demand for synthetic intensity maps and spectra for the three-dimensional (magneto-)hydrodynamic simulations. The necessary radiative transfer calculations, which have to take into account deviations from local thermodynamic equilibrium, are computationally very involved so that no reliable results have been produced so far. Until this task becomes feasible, we have to rely on careful qualitative comparisons of simulations and observations. Here we discuss what effects have to be considered for such a comparison. Nevertheless we are now on the verge of assembling a comprehensive picture of the solar chromosphere in inter-network regions as dynamic interplay of shock waves and structuring and guiding magnetic fields.Comment: 8 pages, 2 figures, to appear in the proceedings of the IAU Symposium No. 247, Waves & Oscillations in the Solar Atmosphere: Heating and Magneto-Seismology (Venezuela 2007

Reversal-free CaIIH profiles: a challenge for solar chromosphere modeling in quiet inter-network

We study chromospheric emission to understand the temperature stratification in the solar chromosphere. We observed the intensity profile of the CaIIH line in a quiet Sun region close to the disk center at the German Vacuum Tower Telescope. We analyze over 10^5 line profiles from inter-network regions. For comparison with the observed profiles, we synthesize spectra for a variety of model atmospheres with a non local thermodynamic equilibrium (NLTE) radiative transfer code. A fraction of about 25% of the observed CaIIH line profiles do not show a measurable emission peak in H_{2v} and H_{2r} wavelength bands (reversal-free). All of the chosen model atmospheres with a temperature rise fail to reproduce such profiles. On the other hand, the synthetic calcium profile of a model atmosphere that has a monotonic decline of the temperature with height shows a reversal-free profile that has much lower intensities than any observed line profile. The observed reversal-free profiles indicate the existence of cool patches in the interior of chromospheric network cells, at least for short time intervals. Our finding is not only in conflict with a full-time hot chromosphere, but also with a very cool chromosphere as found in some dynamic simulations.Comment: 8 pages, accepted in A&

Excitation of Oscillations in the Magnetic Network on the Sun

We examine the excitation of oscillations in the magnetic network of the Sun through the footpoint motion of photospheric magnetic flux tubes located in intergranular lanes. The motion is derived from a time series of high-resolution G band and continuum filtergrams using an object-tracking technique. We model the response of the flux tube to the footpoint motion in terms of the Klein-Gordon equation, which is solved analytically as an initial value problem for transverse (kink) waves. We compute the wave energy flux in upward propagating transverse waves. In general we find that the injection of energy into the chromosphere occurs in short-duration pulses, which would lead to a time variability in chromospheric emission that is incompatible with observations. Therefore, we consider the effects of turbulent convective flows on flux tubes in intergranular lanes. The turbulent flows are simulated by adding high-frequency motions (periods 5-50 s) with an amplitude of 1 km s^{-1}. The latter are simulated by adding random velocity fluctuations to the observationally determined velocities. In this case we find that the energy flux is much less intermittent and can in principle carry adequate energy for chromospheric heating.Comment: 11 pages, 5 figures, figure 1 is in color, all files gzippe

enRoute: dynamic path extraction from biological pathway maps for exploring heterogeneous experimental datasets

Jointly analyzing biological pathway maps and experimental data is critical for understanding how biological processes work in different conditions and why different samples exhibit certain characteristics. This joint analysis, however, poses a significant challenge for visualization. Current techniques are either well suited to visualize large amounts of pathway node attributes, or to represent the topology of the pathway well, but do not accomplish both at the same time. To address this we introduce enRoute, a technique that enables analysts to specify a path of interest in a pathway, extract this path into a separate, linked view, and show detailed experimental data associated with the nodes of this extracted path right next to it. This juxtaposition of the extracted path and the experimental data allows analysts to simultaneously investigate large amounts of potentially heterogeneous data, thereby solving the problem of joint analysis of topology and node attributes. As this approach does not modify the layout of pathway maps, it is compatible with arbitrary graph layouts, including those of hand-crafted, image-based pathway maps. We demonstrate the technique in context of pathways from the KEGG and the Wikipathways databases. We apply experimental data from two public databases, the Cancer Cell Line Encyclopedia (CCLE) and The Cancer Genome Atlas (TCGA) that both contain a wide variety of genomic datasets for a large number of samples. In addition, we make use of a smaller dataset of hepatocellular carcinoma and common xenograft models. To verify the utility of enRoute, domain experts conducted two case studies where they explore data from the CCLE and the hepatocellular carcinoma datasets in the context of relevant pathways