496 research outputs found
Nuclear ashes and outflow in the eruptive star Nova Vul 1670
CK Vulpeculae was observed in outburst in 1670-16721, but no counterpart was
seen until 1982, when a bipolar nebula was found at its location. Historically,
CK Vul has been considered to be a nova (Nova Vul 1670), but a similarity to
'red transients', which are more luminous than classical nova and thought to be
the result of stellar collisions, has re-opened the question of CK Vul's
status. Red transients cool to resemble late M-type stars, surrounded by
circumstellar material rich in molecules and dust. No stellar source has been
seen in CK Vul, though a radio continuum source was identified at the expansion
centre of the nebula. Here we report CK Vul is surrounded by chemically rich
molecular gas with peculiar isotopic ratios, as well as dust. The chemical
composition cannot be reconciled with a nova or indeed any other known
explosion. In addition, the mass of the surrounding gas is too high for a nova,
though the conversion from observations of CO to a total mass is uncertain. We
conclude that CK Vul is best explained as the remnant of a merger of two stars.Comment: an older version of an article that appeared in Nature; published in
Nature, online version, 23 March 201
Gas dynamics in the inner few AU around the Herbig B[e] star MWC297: Indications of a disk wind from kinematic modeling and velocity-resolved interferometric imaging
We present near-infrared AMBER (R = 12, 000) and CRIRES (R = 100, 000)
observations of the Herbig B[e] star MWC297 in the hydrogen Br-gamma-line.
Using the VLTI unit telescopes, we obtained a uv-coverage suitable for aperture
synthesis imaging. We interpret our velocity-resolved images as well as the
derived two-dimensional photocenter displacement vectors, and fit kinematic
models to our visibility and phase data in order to constrain the gas velocity
field on sub-AU scales. The measured continuum visibilities constrain the
orientation of the near-infrared-emitting dust disk, where we determine that
the disk major axis is oriented along a position angle of 99.6 +/- 4.8 degrees.
The near-infrared continuum emission is 3.6 times more compact than the
expected dust-sublimation radius, possibly indicating the presence of highly
refractory dust grains or optically thick gas emission in the inner disk. Our
velocity-resolved channel maps and moment maps reveal the motion of the
Br-gamma-emitting gas in six velocity channels, marking the first time that
kinematic effects in the sub-AU inner regions of a protoplanetary disk could be
directly imaged. We find a rotation-dominated velocity field, where the blue-
and red-shifted emissions are displaced along a position angle of 24 +/- 3
degrees and the approaching part of the disk is offset west of the star. The
visibility drop in the line as well as the strong non-zero phase signals can be
modeled reasonably well assuming a Keplerian velocity field, although this
model is not able to explain the 3 sigma difference that we measure between the
position angle of the line photocenters and the position angle of the dust
disk. We find that the fit can be improved by adding an outflowing component to
the velocity field, as inspired by a magneto-centrifugal disk-wind scenario.Comment: 15 pages, 13 Figure
Die pharmazeutische Gesetzgebung in der Tschechoslowakei seit dem Umsturze. Sammlung 1 der wichtigsten, das Apothekerwesen in der Tschechoslowakei berührenden gesetzlichen Bestimmungen, Verordnungen, behördlichen Erlässe und Entscheidungen. Im Auftrage der Verbandsleitung zusammengestellt von Karl Kraus, Schriftleiter der "Sudetendeutschen Apothekerzeitung". Hrsg. vom Verband deutscher Apotheker in der tschechoslowakischen Republik
The rules for coordinating tax and social security have important differences, and this may be disadvantageous for mobile workers, in particular for posted workers. In this article the differences are analysed and the effects of the rules are shown. The article concludes by giving some suggestions for solving the problem
On the nature of the Herbig B[e] star binary system V921 Scorpii: Geometry and kinematics of the circumprimary disk on sub-AU scales
V921 Scorpii is a close binary system (separation 0.025") showing the
B[e]-phenomenon. The system is surrounded by an enigmatic bipolar nebula, which
might have been shaped by episodic mass-loss events, possibly triggered by
dynamical interactions between the companion and the circumprimary disk (Kraus
et al. 2012a). In this paper, we investigate the spatial structure and
kinematics of the circumprimary disk, with the aim to obtain new insights into
the still strongly debated evolutionary stage. For this purpose, we combine,
for the first time, infrared spectro-interferometry (VLTI/AMBER, R=12,000) and
spectro-astrometry (VLT/CRIRES, R=100,000), which allows us to study the
AU-scale distribution of circumstellar gas and dust with an unprecedented
velocity resolution of 3 km*s^-1. Using a model-independent photocenter
analysis technique, we find that the Br-gamma-line emission rotates in the same
plane as the dust disk. We can reproduce the wavelength-differential
visibilities and phases and the double-peaked line profile using a
Keplerian-rotating disk model. The derived mass of the central star is
5.4+/-0.4 M_sun*(d/1150 pc), which is considerably lower than expected from the
spectral classification, suggesting that V921 Sco might be more distant (d
approx 2kpc) than commonly assumed. Using the geometric information provided by
our Br-gamma spectro-interferometric data and Paschen, Brackett, and Pfund line
decrement measurements in 61 hydrogen recombination line transitions, we derive
the density of the line-emitting gas (N_e=2...6*10^19 m^-3). Given that our
measurements can be reproduced with a Keplerian velocity field without
outflowing velocity component and the non-detection of age-indicating
spectroscopic diagnostics, our study provides new evidence for the
pre-main-sequence nature of V921 Sco.Comment: 17 pages, 11 figures, 3 tables, accepted by Ap
Complexer-YOLO: Real-Time 3D Object Detection and Tracking on Semantic Point Clouds
Accurate detection of 3D objects is a fundamental problem in computer vision
and has an enormous impact on autonomous cars, augmented/virtual reality and
many applications in robotics. In this work we present a novel fusion of neural
network based state-of-the-art 3D detector and visual semantic segmentation in
the context of autonomous driving. Additionally, we introduce
Scale-Rotation-Translation score (SRTs), a fast and highly parameterizable
evaluation metric for comparison of object detections, which speeds up our
inference time up to 20\% and halves training time. On top, we apply
state-of-the-art online multi target feature tracking on the object
measurements to further increase accuracy and robustness utilizing temporal
information. Our experiments on KITTI show that we achieve same results as
state-of-the-art in all related categories, while maintaining the performance
and accuracy trade-off and still run in real-time. Furthermore, our model is
the first one that fuses visual semantic with 3D object detection
Dual Interpretations of Seiberg-Witten and Dijkgraaf-Vafa curves
We give dual interpretations of Seiberg-Witten and Dijkgraaf-Vafa (or matrix
model) curves in n=1 supersymmetric U(N) gauge theory. This duality
interchanges the rank of the gauge group with the degree of the superpotential;
moreover, the constraint of having at most log-normalizable deformations of the
geometry is mapped to a constraint in the number of flavors N_f < N in the dual
theory.Comment: Latex2e, 22 pages, 2 figure
Recommended from our members
Die Pflegestätten des Böhmischen Glases
Seit Jahrhunderten sind die Erzeugnisse der sudetendeutschen Hohlglasindustrie und -veredlung unter der Bezeichnung „Böhmisches Glas" in aller Welt bekannt. Man versteht darunter hauptsächlich ein Kristallglas, (der Zusammensetzung nach ein Kali-Kalkglas), das durch Schliff oder Gravur, durch Ätzen oder Malen veredelt wird. Insbesondere im Ausland ist es verhältnismäßig noch wenig bekannt, daß die engere Heimat der sudetendeutschen Wertarbeit „Böhmisches GIas" im Gebiet von Haida und Steinschönau, im früheren Nordböhmen, liegt. Die Kunst ihrer Herstellung, die dort zu nächst familien- und sippenweise ausgeübt wurde, ist an die Namen Bimann, Böhm, Egermann, PeIikan, Pfeiffer, Pfohl, Pietsch u. a. geknüpft. Die wertvollen Erfahrungen dieser Künstler und Handwerker führten zu besonderen Veredlungsverfahren, die z. T. auch heute noch ausgeführt werden. Um die Erzeugung des Böhmischen Glases technisch und künstlerisch den erhöhten Anforderungen der neuen Zeit anzugleichen, und auch, um ihr die Fortschritte der Wissenschaft dienstbar zu machen, wurden in der zweiten Hälfte des vorigen Jahrhunderts in Haida und Steinschönau, den Brennpunkten der sudetendeutschen Glasindustrie, Fachschulen gegründet, deren Bedeutung heute mehr denn je in der Aufgabe besteht, der deutschen Glasindustrie einen vollwertig technisch und künstlerisch ausgebildeten Nachwuchs zur Verfügung zu stellen. Dieser Nachwuchs hat die Pflicht, der Tradition des Böhmischen Glases durch seine Kenntnisse und Fertigkeiten gerecht zu werden und sie durch sein Schaffen fortzuführen.
Es entspricht der Bedeutung der beiden sudetendeutschen Fachschulen als Pflegestätten des „Böhmischen Glases", wenn in den nachstehenden Veröffentlichungen ihr Werden und Wirken eingehender dargestellt wird
Aluminosis – Detection of an almost forgotten disease with HRCT
The aim of this study was to investigate whether it is possible to detect high-resolution computed tomography (HRCT) findings in aluminium powder workers, which are consistent with early stages of aluminosis. 62 male workers from 8 departments of two plants producing aluminium (Al) powder were investigated using a standardized questionnaire, physical examination, lung function analysis, biological monitoring of Al in plasma and urine, chest X-ray, HRCT and immunological tests. Chronic bronchitis was observed in 15 (24.2%) of the workers, and four workers (6.5%) reported shortness of breath during exercise. HRCT findings in 15 workers (24.2%) were characterized by ill-defined centrilobular nodular opacities. Workers with ill-defined centrilobular nodular opacities had a lower vital capacity than workers who had no such HRCT-findings (90.9 % pred. vs. 101.8 % pred., p = 0.01). Biological monitoring in plasma and urine revealed higher internal exposure to Al in affected workers (33.5 μg/l plasma to 15.4 μg/l plasma, p = 0.01) and (340.5 μg/g creat. to 135.1 μg/g creat., p = 0.007). Years of exposure and concentration of aluminum in urine and plasma appear to be the best predictors for HRCT findings. Age and decreased vital capacity show borderline significance. We conclude that aluminosis is still relevant in occupational medicine. With HRCT it is possible to detect early stages of aluminosis and biological monitoring can be used to define workers at high risk
- …