29 research outputs found
Discovery of an OVI Emitting Nebula around the Hot White Dwarf KPD 0005+5106
A survey of diffuse interstellar sight lines observed with the Far
Ultraviolet Spectroscopic Explorer has led to the serendipitous discovery of a
high-ionization nebula around the hot white dwarf KPD 0005+5106. The nebula has
an OVI 1032A surface brightness of up to 25,000 photons/s/cm^2/sr, making it
the brightest region of extended OVI emission in our survey. Photoionization
models using the incident white dwarf continuum successfully reproduce the
observed OVI intensity. The OVI emission arises in the highly ionized inner
region of a planetary nebula around KPD 0005+5106. This newly discovered nebula
may be one member of a class of high-ionization planetary nebulae that are
difficult to detect in the optical, but which can be easily identified in the
ultraviolet.Comment: accepted for publication in ApJL, 11 pages including 2 figure
An Extended FUSE Survey of Diffuse O VI Emission in the Interstellar Medium
We present a survey of diffuse O VI emission in the interstellar medium
obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). Spanning 5.5
years of FUSE observations, from launch through 2004 December, our data set
consists of 2925 exposures along 183 sight lines, including all of those with
previously-published O VI detections. The data were processed using an
implementation of CalFUSE v3.1 modified to optimize the signal-to-noise ratio
and velocity scale of spectra from an aperture-filling source. Of our 183 sight
lines, 73 show O VI 1032 emission, 29 at > 3-sigma significance. Six of the
3-sigma features have velocities |v_LSR| > 120 km/s, while the others have
|v_LSR| < 50 km/s. Measured intensities range from 1800 to 9100 LU, with a
median of 3300 LU. Combining our results with published O VI absorption data,
we find that an O VI-bearing interface in the local ISM yields an electron
density n_e = 0.2--0.3 cm^-3^ and a path length of 0.1 pc, while O VI-emitting
regions associated with high-velocity clouds in the Galactic halo have
densities an order of magnitude lower and path lengths two orders of magnitude
longer. Though the O VI intensities along these sight lines are similar, the
emission is produced by gas with very different properties.Comment: 27 pages, 16 figures, accepted by Ap
FUSE Detection of Galactic OVI Emission in the Halo above the Perseus Arm
Background observations obtained with the Far Ultraviolet Spectroscopic
Explorer (FUSE) toward l=95.4, b=36.1 show OVI 1032,1038 in emission. This
sight line probes a region of stronger-than-average soft X-ray emission in the
direction of high-velocity cloud Complex C above a part of the disk where
Halpha filaments rise into the halo. The OVI intensities, 1600+/-300
ph/s/cm^2/sr (1032A) and 800+/-300 ph/s/cm^2/sr (1038A), are the lowest
detected in emission in the Milky Way to date. A second sight line nearby
(l=99.3, b=43.3) also shows OVI 1032 emission, but with too low a
signal-to-noise ratio to obtain reliable measurements. The measured
intensities, velocities, and FWHMs of the OVI doublet and the CII* line at
1037A are consistent with a model in which the observed emission is produced in
the Galactic halo by hot gas ejected by supernovae in the Perseus arm. An
association of the observed gas with Complex C appears unlikely.Comment: accepted for publication in ApJL, 11 pages including 3 figure
X-Ray Searches for Emission from the WHIM in the Galactic Halo and the Intergalactic Medium
At least 50% of the baryons in the local universe are undetected and
predicted to be in a hot dilute phase (1E5-1E7 K) in low and moderate
overdensity environments. We searched for the predicted diffuse faint emission
through shadowing observations whereby cool foreground gas absorbs more distant
diffuse emission. Observations were obtained with Chandra and XMM-Newton. Using
the cold gas in two galaxies, NGC 891 and NGC 5907, shadows were not detected
and a newer observation of NGC 891 fails to confirm a previously reported X-ray
shadow. Our upper limits lie above model predictions. For Local Group studies,
we used a cloud in the Magellanic Stream and a compact high velocity cloud to
search for a shadow. Instead of a shadow, the X-ray emission was brighter
towards the Magellanic Stream cloud and there is a less significant brightness
enhancement toward the other cloud also. The brightness enhancement toward the
Magellanic Stream cloud is probably due to an interaction with a hot ambient
medium that surrounds the Milky Way. We suggest that this interaction drives a
shock into the cloud, heating the gas to X-ray emitting temperatures.Comment: 10 ApJ pages with 10 figure
α-Synuclein in human cerebrospinal fluid is principally derived from neurons of the central nervous system
The source of Parkinson disease-linked α-synuclein (aSyn) in human cerebrospinal fluid (CSF) remains unknown. We decided to measure the concentration of aSyn and its gradient in human CSF specimens and compared it with serum to explore its origin. We correlated aSyn concentrations in CSF versus serum (QaSyn) to the albumin quotient (Qalbumin) to evaluate its relation to bloodâCSF barrier function. We also compared aSyn with several other CSF constituents of either central or peripheral sources (or both) including albumin, neuron-specific enolase, ÎČ-trace protein and total protein content. Finally, we examined whether aSyn is present within the structures of the choroid plexus (CP). We observed that QaSyn did not rise or fall with Qalbumin values, a relative measure of bloodâCSF barrier integrity. In our CSF gradient analyses, aSyn levels decreased slightly from rostral to caudal fractions, in parallel to the recorded changes for neuron-specific enolase; the opposite trend was recorded for total protein, albumin and ÎČ-trace protein. The latter showed higher concentrations in caudal CSF fractions due to the diffusion-mediated transfer of proteins from blood and leptomeninges into CSF in the lower regions of the spine. In postmortem sections of human brain, we detected highly variable aSyn reactivity within the epithelial cell layer of CP in patients diagnosed with a range of neurological diseases; however, in sections of mice that express only human SNCA alleles (and in those without any Snca gene expression), we detected no aSyn signal in the epithelial cells of the CP. We conclude from these complementary results that despite its higher levels in peripheral blood products, neurons of the brain and spinal cord represent the principal source of aSyn in human CSF
FAMOUS II - LoSec: Ermittlung des Level of Security an Flughaefen
Airport security became an important part of airport operations. A lot of information is required to be able to fuly assess the security situation at an airport. Often valuable information is not passed on to the security control center, but remains locally limited knowledge of the personnel at location. These pieces of information have to be delivered not only to the security control center, but also to the future airport operation center (APOC) in a useful way. Following the Level of Service parameter (LoS) that evaluates punctuality, etc. at an airport, the Level of Security indicator (LoSec) is being developed which allows the stakeholders at the APOC to capture the entire security situation at a glance. Since many security-related parameters cannot be quantified in an unambiguous way, fuzzy logic is used that makes calculations with imprecise measures possible and thus allows the computational evaluation of the threat level at an airport under consideration of the experience and knowledge of the security personnel
Besondere Belastungssituationen von MÀnnern in frauendominierten Berufen - speziell im Berufsfeld Erzieher in KindertagesstÀtten
Die Bachelorarbeit befasst sich mit der besonderen Situation von MĂ€nnern im Erzieherberuf. Dabei wird sich auf den Bereich der KindertagesstĂ€tten beschrĂ€nkt. Gegenstand der Untersuchung sind besondere Belastungssituationen fĂŒr Erzieher im Berufsfeld. Die Arbeit gliedert sich in einen Teil mit Li-teraturrecherche zu den Themen Sozialisation und Gender. Dieser bildet die Grundlage fĂŒr die Entwicklung der Forschungsfrage. Den zweiten Teil bildet eine praktische Erhebung mittels fĂŒnf leitfadengestĂŒtzter Interviews in Chemnitzer KindertagesstĂ€tten und deren Auswertung. Die Ergebnisse der Untersuchung tragen keinen Beweischarakter, sondern sind als exemplarisch zu werten. Sie sollen in der Literatur erwĂ€hnte Problemstellungen verdeutlichen und Hinweise geben, wie Belastungssituationen einzuschĂ€tzen sind und ihnen entgegengewirkt werden kann